BACKGROUND:Mosaic variants represent a significant but underrecognized contributor to human disease such as cancer and immune diseases. Despite advances in genetic diagnostics, mosaic variant detection remains challenging as a result of low variant allele fractions, tissue specificity, and clinical heterogeneity. OBJECTIVE:We investigated the prevalence, diagnostic impact, and clinical relevance of mosaic variants in participants with immune disorders. METHODS:Exome sequencing of blood and/or saliva was performed in 2655 participants, including 2064 affected participants. Mosaic variants were detected using two algorithms, LoFreq2 and Mutect2. A subset of the detected variants was orthogonally validated. Clinical data were retrospectively analyzed to assess the clinical significance of these variants. RESULTS:Mosaic variants associated with immune disorders contributed to a molecular diagnosis in 29 (1.4%) of 2064 affected participants. Notably, 9 (31%) of 29 of diagnostic variants were missed by standard germline analysis as a result of low variant allele fractions. Clinically relevant parental mosaicism was ascertained in two families. Enrichment of mosaic variants was observed in clonal hematopoiesis-related genes driven by older age and GATA2 deficiency, with prognostic implications for hematologic disorders. Finally, chemotherapy drug resistance variants in NRAS, KRAS, and IDH2 were identified, demonstrating the potential for mosaic variant detection to inform treatment strategies. CONCLUSION:Mosaic variants contribute significantly to the molecular diagnosis and prognosis of immune and hematologic disorders and are missed by typical germline variant-calling workflow.

Autoinflammation typically arises from mutations affecting molecules such as inflammasome backbones that give rise to gain-of-function (GOF) pro-inflammatory activity requiring little or no normal ligand stimulation. This has been assumed to be the case in the auto-inflammation known as Blau syndrome wherein mutations usually present in the nucleotide oligomerization domain of the CARD15 gene encoding NOD2 result in widespread granulomatous inflammation, seemingly in the absence of NOD2 stimulation by its canonical ligand, muramyl dipeptide (MDP); moreover, despite such lack of ligand stimulation, NOD2 bearing a Blau mutation is thought to cause inflammation by initiating conventional downstream signaling that ultimately results in NF-κB activation. However, newer data concerning Blau syndrome pathogenesis suggest a more complex picture in which Blau CARD15 mutations cause inflammation by unconventional and/or loss of conventional signaling and which depend, at least in part, from a genetic defect which arises from loss-of-function pro-inflammatory activity. In this review, we present and analyze these newer data with the aim of defining a further pathway to the understanding and treatment of this disease.

Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) is an intracellular innate immune sensor. Its functions have been extensively studied. Variants in the NOD2 gene are associated with several human diseases. This report provides a comprehensive review of these diseases and biomedical and immunological roles of NOD2. Blau syndrome is an autosomal dominant disease primarily occurring in children and is caused by highly penetrant NOD2 variants. Approximately 40

In the present study, we explored the relation of LRRK2-kinase phosphorylation of the NLRC4 inflammasome to NLRC4 inflammasome function in normal humans and mice, as well as in patients with Crohn’s disease (CD). We found that LRRK2-kinase was both necessary and sufficient for NLRC4 phosphorylation in human mononuclear cells and likely in murine mononuclear cells as well. In addition, such phosphorylation requires ASC association with the nascent NLRC4 inflammasome and is necessary for ASC function. Finally, we found that inhibition of LRRK2-kinase phosphorylation of NLRC4 impairs inflammasome IL-1β production but has little to no effect on its IL-18 production. The mechanism of this dichotomy was revealed in studies of NLRC4 inflammasome activity, showing that pro-IL-1β cleavage is partially dependent on LRRK2-mediated ASC binding and cleavage function, whereas pro-IL-18 is independent of such ASC function. In accompanying studies of circulating cells from patients with CD, a disease associated with LRRK2 polymorphisms that affect LRRK2 expression, we showed that patient cells exhibited increased NLRC4 inflammasome activation; in addition, inhibition of LRRK2-kinase impaired IL-1β secretion but had little or no effect on IL-18 secretion by patient cells. Finally, studies of WT mice or mice with epithelial cell-specific NLRC4 deletion revealed that NLRC4 inflammasome activation causes impairment of gut barrier function that is abrogated by inhibition of LRRK2-kinase activity. Thus, NLRC4 inflammasome function is increased in CD, and its regulation by an LRRK2-kinase inhibitor is calibrated to prevent NLRC4-mediated barrier dysfunction.

Type 1 autoimmune pancreatitis (AIP) and systemic lupus erythematosus (SLE) are caused by type I IFNs secreted by plasmacytoid dendritic cells (pDCs). Our understanding of the immune consequences before and after pDC activation in SLE is expanding, whereas knowledge on those in AIP are insufficient. In this article, we summarize the similarities and dissimilarities in pDC activation between AIP and SLE. In SLE, neutrophil extracellular traps containing self-DNA, anti-microbial peptides, and endogenous alarmins form anti-DNA antibody complexes, promoting type I IFN production by pDCs. Type I IFNs produced by pDCs function as initiators rather than effectors in SLE, as evidenced by the fact that these cytokines induce the maturation of conventional DCs (cDCs) leading to the expansion of autoreactive T cells and B cells. Notably, type I IFNs produced by pDCs were observed at the maturation phase but not at the induction phase in experimental AIP. Mechanistically, cDCs producing type I IFNs, C-X-C motif chemokine ligand 9 (CXCL9), and CXCL10 are initiator cells of AIP, and C-X-C chemokine receptor 3 (CXCR3)+T helper type 1(Th1) cells migrate to the pancreas in response to CXCL9 and CXCL10. CXCR3+Th1 cells produce C-C chemokine ligand 25 (CCL25) to attract C-C chemokine receptor 9 (CCR9)+pDCs to the pancreas. Pancreatic pDCs producing type I IFNs, CXCL9, CXCL10, and CXCR3+Th1 cells producing CCL25 form a positive feedback loop in which the sensing of intestinal dysbiosis induces large amounts of type I IFNs by pDCs.

SummaryBackground and AimsLiver involvement is an increasingly recognised complication of common variable immunodeficiency (CVID). Nodular regenerative hyperplasia (NRH), a subgroup of porto‐sinusoidal vascular disorder, and manifestations of portal hypertension (PH) unrelated to cirrhosis are the most common findings. Nonetheless, the evolution of liver disease over time remains unknown.MethodsRetrospective review of patients followed at the National Institutes of Health with CVID‐related liver disease and liver biopsy from 1990 to 2020. Clinical, imaging and histological follow‐up were recorded as part of clinical research protocols.ResultsForty patients were included, with a median age of 37.5 years at initial biopsy, 73% presenting with clear evidence of NRH, and a median fibrosis stage of 1. At biopsy, median platelet count was 100 × 109/L, spleen size 19.5 cm, hepatic venous pressure gradient 9.5 mmHg and 37.5% of patients had signs of PH. Cumulative incidence of PH was 65% at 5 years. In a subgroup of 16 patients, a follow‐up liver biopsy, performed at a median time of 3 years after the index biopsy, revealed an increase in fibrosis by ≥2 stages in 31% of cases and an increase to an overall stage of 2.2 (p = 0.001). No clinical or histological factors were associated with progression of fibrosis.ConclusionsIn this CVID cohort, NRH is the most common initial histological finding; however, unexpectedly fibrosis progresses over time in a subgroup of patients. A better understanding of the underlying causal process of liver disease CVID might lead to improved outcomes.

The pathogenesis of the murine model of autoimmune pancreatitis associated with IgG4-related disease (AIP/IgG4-RD) induced by administration of polyinosinic-polycytidylic acid (poly[I:C]) is incompletely understood. While it is known that murine and human AIP/IgG4-RD is driven by plasmacytoid dendritic cells (pDCs) producing IFN-α, the origin of these cells and their relation to effector T cells is not known. Here, we show that murine AIP was initiated by TLR3-bearing conventional DCs in the uninflamed pancreas whose activation by the TLR3 ligand poly(I:C) caused IFN-α, CXCL9, and CXCL10 secretion. This, in turn, induced pancreatic recruitment of CXCR3+ T cells and these T cells, via their secretion of CCL25, facilitated migration of pDCs bearing CCR9 into the pancreas. This established a feedback loop anchored by the now dominant pDC production of IFN-α and the continued CXCR3+ T cell facilitation of pDC migration. Remarkably, the interaction between CXCR3+ T cells and pDCs also existed at the functional level since this interaction enhanced the production of CCL25 and IFN-α by CXCR3+ T cells and pDCs, respectively. Evidence presented here that a similar disease mechanism was present in human AIP/IgG4-RD creates new avenues of disease treatment.

Abstract The LRRK2 protein associated with increased risk of IBD. Recently described, this protein influences NLRC4 inflammasome phosphorylation. This LRRK2 function, however, has uncertain significance since it is not clear how NLRC4 phosphorylation affects NLRC4 inflammasome function.This study utilizes commercially available LRRK2 inhibitors, to clarify this knowledge gap. In vitro studies showed that inhibition of LRRK2 kinase activity inhibits both its binding to NLRC4 and phosphorylation upon activation with needle protein, thus establishing that LRRK2 has an indispensable role for NLRC4 phosphorylation. later using THP-1 cells with ASC deletion or human PBMC-derived dendritic cells with shRNA ASC- KD showed that ASC deficiency retards NLRC4 phosphorylation. Finally, we found that inhibition of NLRC4 phosphorylation by LRRK2 inhibitors has a major negative effect on NLRC4 mediated IL-1b cleavage but, surprisingly, it has minor effect on IL-18 cleavage. This indicated that IL-1b expression requires ASC-caspase binding whereas IL-18 expression does not. Next, systemic administration of NLRC4 activator (flagellin protein) caused increased intestinal permeability and that co-administration of inhibitor reversed the increased permeability. These findings concluded that inhibition of IL-1b production with the preservation of IL-18 via LRRK2 kinase inhibition blocks the potentially harmful effects of NLRC4 activity on intestinal permeability during intestinal inflammation.

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The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor expressed in hematopoietic and non-hematopoietic cells. Activation of the AhR by xenobiotics, microbial metabolites, and natural substances induces immunoregulatory responses. Autoimmune pancreatitis (AIP) is a chronic fibroinflammatory disorder of the pancreas driven by autoimmunity. Although AhR activation generally suppresses pathogenic autoimmune responses, the roles played by the AhR in AIP have been poorly defined. In this study, we examined how AhR activation affected the development of experimental AIP caused by the activation of plasmacytoid dendritic cells producing IFN-α and IL-33. Experimental AIP was induced in MRL/MpJ mice by repeated injections of polyinosinic-polycytidylic acid. Activation of the AhR by indole-3-pyruvic acid and indigo naturalis, which were supplemented in the diet, inhibited the development of experimental AIP, and these effects were independent of the activation of plasmacytoid dendritic cells producing IFN-α and IL-33. Interaction of indole-3-pyruvic acid and indigo naturalis with AhRs robustly augmented the production of IL-22 by pancreatic islet α cells. The blockade of IL-22 signaling pathways completely canceled the beneficial effects of AhR ligands on experimental AIP. Serum IL-22 concentrations were elevated in patients with type 1 AIP after the induction of remission with prednisolone. These data suggest that AhR activation suppresses chronic fibroinflammatory reactions that characterize AIP via IL-22 produced by pancreatic islet α cells.

It was a dark moment to learn that on October 23, 2022, the distinguished Swedish mucosal immunologist and our dear colleague and friend Nils Lycke had passed away. It was untimely and it was unfair. Nils was only 68 years old and by right had many years left to contribute to the community of mucosal immunologists, to his many friends, to his family, and most of all, to his wife Susanna; however, this was not to be. Except for a postdoc period at the National Institutes of Health, Nils spent his career in Gothenburg, Sweden. After medical studies and an MD degree in 1980 at the University of Gothenburg and a brief sojourn in pharmacology research, he embarked on his definitive pathway as a mucosal immunologist by joining Jan Holmgren’s laboratory in 1982. He obtained his PhD in 1986, with his thesis “Cholera Toxin and the Intestinal Immune Response” leading to six published papers. From 1987–1989, Nils capped his training with a stay at the Warren Strober Lab at the National Institutes of Health, during which he cemented his plans to focus on the adjuvant properties of cholera toxin (CT). Upon returning to Gothenburg, Nils started his own laboratory, and in the 1990s made notable advances that established his reputation as a productive and innovative scientist. By 2000, he was appointed Professor and Head of the Department of Clinical Immunology at the University of Gothenburg and also the Chief Hospital Physician for the Sahlgrenska University Clinical Immunology Laboratory. In 2006, he established and became Director of the Mucosal Immunobiology and Vaccine Center, a center of excellence funded by the Swedish government. In the ensuing years, the Mucosal Immunobiology and Vaccine Center and the Lycke Laboratory in particular supervised more than 20 PhD students, as well as 15 postdoctoral Fellows, many of whom also having become independent scientists. In total, Nils published almost 200 papers, including many influential and field-defining review articles, and he was a regular keynote speaker at international meetings on mucosal immunology and vaccinology. Nils’s research led to fundamental advances in our knowledge of the mucosal immune system and of the use of CT-based vaccine vectors in particular. Having first shown that oral CT elicits a powerful adjuvant effect on mucosal responses, he then demonstrated that this reflects the effects of CT on both B cells and T cells. These included an essential ability to drive isotype switching to immunoglobulin A production in mucosal B cells, and further work established that the adjuvant properties of CT resided mainly in the A subunit of CT and were mediated through its adenosine diphosphate ribosyltransferase activity. Nils then devised an ingenious way of overcoming this direct link between the adjuvant effects and toxicity of CT by generating a fusion protein that consisted of the A subunit linked to the B cell binding domain of Staphylococcal protein A. This CTA1-DD fusion protein had the same capacity to augment T- and B-cell responses as native CT but was completely nontoxic. In the next years, Nils and his colleagues proved the validity of this new vaccination strategy, showing that CTA1-DD could be used as a platform for effective oral or intranasal immunization against a variety of pathogens including Helicobacter pylori, Chlamydia, influenza A, and even HIV. It was also sufficiently robust to be incorporated into vehicles, such as nanoparticles, and International Student Congress Of (bio)Medical Sciences for targeting additional immune cells, such as dendritic cells. In contrast to the potent ability of native CTA1-DD to drive active immunity, a CTA1R7K-DD fusion protein engineered to lack adenosine diphosphate-ribosylating activity was able to elicit tolerance to co-administered antigen through the induction of interleukin-10-producing T cells and could ameliorate experimental autoimmune disease. Although much of the focus of Nils’s research was to understand the fundamental mechanisms underlying the flexibility of CTA1-DD, he also made a particular point of exploring the translational relevance of vaccine vectors, engaging productively with colleagues in industry, and he was the co-inventor of a number of patents. A further topic of particular interest for Nils was to understand mucosal B-cell function at the cellular and molecular level. In particular, he generated a number of seminal insights into how immunological memory is induced and disseminated during mucosal immunoglobulin A responses primed in Peyer’s patches. Like his work on CT-based adjuvants, these studies highlighted the imaginative and sophisticated mastery of cutting-edge technique that was a hallmark of Nils’s career. In addition to his outstanding scientific accomplishments in Gothenburg, Nils had an equally notable record as a contributor to the international community of immunologists, especially in Europe. This was manifest in his penchant for collaboration and networking and in his work as Editor or Associate Editor for many journals, including Frontiers in Immunology, Mucosal Immunology, Immunology, and the Scandinavian Journal of Immunology. He was a co-founder of the European Mucosal Immunology Group and an outstanding organizer of international conferences. Nils’s achievements as a scientist were matched by great personal qualities. His family, with his wife, Susanna Lycke Cardell, herself a professor in immunology, his four children and many grandchildren, and not the least, his father were always close to his heart. Nils was a deeply cultural person in the best sense of the word, with a great interest in music and art. He appreciated nature and the sea, and in winter he loved long-distance skating and skiing. He was also a lover of good food, and he liked the art of cooking and enjoyed experimenting in the kitchen to the appreciation of his large circle of friends. A distinguished researcher, warm-hearted family man, faithful colleague, and friend has left us much too early. We will all miss Nils’s humor, warmth, zest for life, and brilliance.

Supplementary Figure 1. Cdx2 expression in human gastric epithelial cell lines. Supplementary Figure 2. The expression of Cdx2 was enhanced by H. pylori infection in gastric epithelial cell. Supplementary Figure 3. Scheme of the Cdx2 prmoter-luciferase reporter plasmids used in this study. Supplementary Figure 4. BAY11-7082 inhibits NF-κB activation. Supplementary Figure 5. NOD1 siRNA reduced the expression of NOD1. Supplementary Figure 6. Cdx2 and MUC2 expression in GSM06 cells. Supplementary Figure 7. Pretreatment with iE-DAP reduces H. pylori infection-induced Cdx2 expression. Supplementary Figure 8. iE-DAP alone does not alter Cdx2 expression. Supplementary Figure 9. Inflammatory scores of the stomach did not differ between NOD1-intact and NOD1-deficient mice. Supplementary Figure 10. TNF-α was induced in the stomachs of H. pylori-infected mice.

Emerging evidence implicates intestinal involvement in the onset and/or progression on the selective degeneration of dopaminergic neurons characterizing Parkinson's disease (PD). On the one hand, there are studies supporting the Braak hypothesis that holds that pathologic α-synuclein, a hallmark of PD, is secreted by enteric nerves into intestinal tissue and finds its way to the central nervous system (CNS) via retrograde movement in the vagus nerve. On the other hand, there is data showing that cells bearing leucine-rich repeat kinase 2 (LRRK2), a signaling molecule with genetic variants associated with both PD and with inflammatory bowel disease, can be activated in intestinal tissue and contribute locally to intestinal inflammation, or peripherally to PD pathogenesis via cell trafficking to the CNS. Importantly, these gut-centered factors affecting PD development are not necessarily independent of one another: they may interact and enhance their respective pathologic functions. In this review, we discuss this possibility by analysis of studies conducted in recent years focusing on the ability of LRRK2 to shape immunologic responses and the role of α-synuclein in influencing this ability.

In this issue of Cellular and Molecular Gastroenterology and Hepatology, Peek et al1Peek C.T. Ford C.A. Eichelberger K.R. Jacobse J. Torres T. Maseda D. et al.Intestinal inflammation promotes MDL-1+ osteoclast precursor expansion to trigger osteoclastogenesis and bone loss.Cell Mol Gastroenterol Hepatal. 2022; (xx:xxx–xxx)Abstract Full Text Full Text PDF Google Scholar provide important new insight into the osteoclast signaling underlying the bone loss occurring in inflammatory bowel disease (IBD). Initially, these investigators show, using both noninfectious and infectious murine models, that loss of trabecular bone is a universal consequence of gut inflammation. This, they go on to show, is associated with increased bone levels of an array of cytokines and chemokines, most notably granulocyte colony-stimulating factor (CSF), tumor necrosis factor α (TNF-α), interleukin (IL)12, and MCP-1 (CCL-2), but no increases in levels of downstream effector cytokines, interferon-γ and IL17. In addition, these increases occurred pare passu, with increases in various osteoclast progenitor cells (OPCs) such as lineage-negative Sca-1+ cells, c-Kit+ (LSK+) cells, and CD11b-/loLy6Chi cells within the bone marrow. These findings were taken as evidence that the cytokines and chemokines were acting by promoting osteoclast progenitor development and trafficking; however, the possibility that they also were stimulating osteoclast formation and activity was not ruled out. In accompanying further studies, the investigators found that macrophage CSF, a major inducer of osteoclastogenesis, was increased only modestly and relatively late during DSS-colitis inflammation, whereas RANK, another major inducer, was not measured, its receptor was decreased on OPCs during colitis. This indicates that gut inflammation-associated bone loss is not caused primarily by changes in the level/activity of these major inducers, as perhaps equivocally suggested in previous studies.2Moschen A.R. Kaser A. Enrich B. Ludwiczek O. Gabriel M. Obrist P. Wolf A.M. Tilg H. The RANKL/OPG system is activated in inflammatory bowel disease and relates to the state of bone loss.Gut. 2005; 54: 4479-4487Crossref Scopus (188) Google Scholar,3Franchimont N. Reenaers C. Lambert C. Belaiche J. Bours V. Malaise M. Delvenne P. Louis E. Increased expression of receptor activator of NF-kB ligand (RANKL), its receptor RANK and its decoy receptor osteoprotegerin in the colon of Crohn’s disease patients.Clin Exp Immunol. 2004; 138: 491-498Crossref PubMed Scopus (60) Google Scholar On the other hand, the osteoclastogenesis was associated with enhanced OPC expression of RANK/CSF1R co-receptors, especially MDL-1 (CLEC5A). Thus, it emerged that bone loss in IBD is owing to increased expression of 1 (or more) receptor providing co-stimulation, rather than those providing primary stimulation of osteoclast precursors. Based on these findings, Peek et al1Peek C.T. Ford C.A. Eichelberger K.R. Jacobse J. Torres T. Maseda D. et al.Intestinal inflammation promotes MDL-1+ osteoclast precursor expansion to trigger osteoclastogenesis and bone loss.Cell Mol Gastroenterol Hepatal. 2022; (xx:xxx–xxx)Abstract Full Text Full Text PDF Google Scholar examined the effect of administration of antagonistic anti–MDL-1 on bone loss occurring during colitis and, indeed, showed that MDL-1 neutralization impeded such loss. The question therefore arises as to whether IBD-associated bone loss can and should be treated with an MDL-1 inhibitor. MDL-1, a C-type lectin, is a component of the remarkably complex signaling program that guides the development and/or activation of osteoclasts.4Humphrey M.B. Nakamura M.C. A comprehensive review of immunoreceptor regulation of osteoclasts.Clin Rev Allergy Immunol. 2016; 51: 48-58Crossref PubMed Scopus (45) Google Scholar A somewhat simplified description of its function is that MDL-1 is one of several co-receptors whose activation is necessary for stimulation of osteoclastogenesis by the primary osteoclast activators RANKL (acting via RANK) and/or macrophage CSF (acting via CSF1R).5Teitelbaum S.L. Bone resorption by osteoclasts.Science. 2000; 289: 1504-1508Crossref PubMed Scopus (2967) Google Scholar When stimulated by its ligand, MDL-1 provides such co-activation via activation of intracellular signaling adaptors adjacent to the cell membrane, ITAM-harboring proteins called DAP12 and DAP10.6Inui M. Kikuchi Y. Aoki N. Maeda T. Sugahara-Tibinai A. Fujimura S. et al.Signal adaptor DAP10 associates with MDL-1 and triggers osteoclastogenesis in cooperation with DAP12.Proc Natl Acad Sci U S A. 2009; 106: 4816-4821Crossref PubMed Scopus (49) Google Scholar In this respect, MDL-1 is closely related to another co-receptor, TREM2, which also signals through DAP12 and DAP10 and is distantly related to other co-receptors, PIR-A and OSCAR, that use another ITAM-harboring protein. The latter also serves yet other osteoclastogenic co-stimulators, various Fcγ receptors. As if this signaling program was not complicated enough, it should be added that osteoclastogenesis also is regulated by an Fcγ receptor acting through an ITIM-harboring protein that in this case results in a negative signal. Why this complexity? One possibility is that each co-receptor, by acting through its specific ligand, allows regulation of osteoclastogenesis to be tailored to particular microenvironments and/or situations. The endogenous ligand for MDL-1 is not known and therefore it is not known whether increases in its level is unique to gut inflammation and as such is specifically necessary for bone loss occurrence in this circumstance. MDL-1 is expressed on myeloid cells other than osteoclasts or their precursors and in fact is highly expressed on macrophages upon stimulation by TNF-α (but not interferon-γ).7Joyce-Shaikh B. Bigler M.E. Chao C.-C. Murphy E.E. Blumenschein W.M. Adamopoulos I.E. et al.Myeloid DAP12-associating lectin (MDL)-1 regulates synovial inflammation and bone erosion associated with autoimmune arthritis.J Exp Med. 2010; 207: 579-589Crossref PubMed Scopus (61) Google Scholar This suggests that MDL-1 signaling subtends a range of responses other than those related to osteoclastogenesis. This possibility is supported by the observation that mice lacking MDL-1 show decreased experimental arthritis and mice administered agonistic anti–MDL-1 show increased arthritis and cytokines driving the latter.7Joyce-Shaikh B. Bigler M.E. Chao C.-C. Murphy E.E. Blumenschein W.M. Adamopoulos I.E. et al.Myeloid DAP12-associating lectin (MDL)-1 regulates synovial inflammation and bone erosion associated with autoimmune arthritis.J Exp Med. 2010; 207: 579-589Crossref PubMed Scopus (61) Google Scholar In addition, it is supported by the fact that in the study under discussion, antagonistic anti–MDL-1 administration ameliorated DSS colitis to some extent. This opens the door to the possibility that the decreased bone loss observed was in part the result of decreased underlying inflammation. The question posed earlier and still to be addressed is whether prevention of bone loss by specific blockade of osteoclast activity, such as that achieved with anti–MDL-1, rather than by blockade of the underlying inflammation, is a worthwhile clinical goal. Peek et al1Peek C.T. Ford C.A. Eichelberger K.R. Jacobse J. Torres T. Maseda D. et al.Intestinal inflammation promotes MDL-1+ osteoclast precursor expansion to trigger osteoclastogenesis and bone loss.Cell Mol Gastroenterol Hepatal. 2022; (xx:xxx–xxx)Abstract Full Text Full Text PDF Google Scholar are conservative in their answer to this question in that they suggest that specific therapy may be limited to those patients whose disease cannot be completely controlled by standard antibiologic therapy and then only in conjunction with the latter. However, they did not provide data on whether biologic therapy such as administration of anti–TNF-α or anti-IL12p40 alone provide as much amelioration of bone loss as anti–MDL-1. Until this question is answered, use of anti–MDL-1 must be held in abeyance. Intestinal Inflammation Promotes MDL-1+ Osteoclast Precursor Expansion to Trigger Osteoclastogenesis and Bone LossCellular and Molecular Gastroenterology and HepatologyPreviewInflammatory bowel disease (IBD) is characterized by severe gastrointestinal inflammation, but many patients experience extra-intestinal disease. Bone loss is one common extra-intestinal manifestation of IBD that occurs through dysregulated interactions between osteoclasts and osteoblasts. Systemic inflammation has been postulated to contribute to bone loss, but the specific pathologic mechanisms have not yet been fully elucidated. We hypothesized that intestinal inflammation leads to bone loss through increased abundance and altered function of osteoclast progenitors. Full-Text PDF Open Access

Abstract The leucine-rich repeat kinase 2 (LRRK2) gene is a genetic hotspot for gain-of-function mutations associated with various diseases such as Crohn’s and Parkinson’s disease. These mutations enhance LRRK2 kinase activity and, consequently, various inhibitors of this activity are currently being tested as treatment modalities. Here, we report studies of two novel kinase inhibitors (Termed CS-190 and CS-82) with LRRK2 inhibition activity. In vitro studies disclosed that the two inhibitors suppress LRRK2 phosphorylation as well as its ability to phosphorylate the LRRK2 targets, Rab 10 and 12; in addition, they suppress human dendritic cell production of TNFa stimulated by several known LRRK2 activators including the Dectin-1-ligand, zymosan-depleted S. cerevisiae extract. Finally, the inhibitors exhibited powerful suppression of the ability of LRRK2 to mediate NLRC4 inflammasome production of IL-1beta. These in vitro finding correlated with in vivo studies showing that IP administration of one of the kinase inhibitors (CS-82) ameliorates colitis in the DSS-colitis model as evaluated by weight loss and inflammation scores. These findings suggest that these newly developed inhibitors are potential agents for treatment of Crohn’s disease.

Chromosomal microarray (CMA) enables the detection of copy number changes within exon or gene-level resolution depending on probe density and gene coverage. Genome sequencing (GS) can circumvent these resolution issues through detection of smaller copy number changes enabled by uniformity of coverage that is not possible by exome sequencing (ES). Copy number variants (CNVs) can add to the diagnostic yield of inborn errors of immunity (IEI); however, the role of genome sequencing in identifying CNVs in IEI is not well understood.

The mechanisms by which the ATG16L1(T300A) polymorphism affects cell function and causes an increased risk for the development of Crohn disease remain incompletely understood. Here we report that healthy individuals and mice bearing this polymorphism, even as heterozygotes, manifest enhanced TLR, and NLR cytokine and chemokine responses due to increased activation of NFKB. We elucidated the mechanism of the NFKB abnormality and found that in the ATG16L1(T300A) cell, there is enhanced polyubiquitination of TRAF6 or RIPK2 resulting from the accumulation of SQSTM1/p62. Indeed, knockout of Sqstm1 in autophagy-deficient cells almost completely normalized TRAF6 or RIPK2 polyubiquitination and NFKB activation in these cells. Thus, by identifying that autophagy is a pathway-intrinsic homeostatic mechanism that restricts excessive TLR- or NLR-mediated inflammatory signaling, our findings shed new light on how the ATG16L1(T300A) polymorphism sets the stage for the occurrence of Crohn disease.

BACKGROUND:Prospective genetic evaluation of patients at this referral research hospital presents clinical research challenges.OBJECTIVES:This study sought not only a single-gene explanation for participants' immune-related presentations, but viewed each participant holistically, with the potential to have multiple genetic contributions to their immune phenotype and other heritable comorbidities relevant to their presentation and health.METHODS:This study developed a program integrating exome sequencing, chromosomal microarray, phenotyping, results return with genetic counseling, and reanalysis in 1505 individuals from 1000 families with suspected or known inborn errors of immunity.RESULTS:Probands were 50.8% female, 71.5% were ≥18 years, and had diverse immune presentations. Overall, 327 of 1000 probands (32.7%) received 361 molecular diagnoses. These included 17 probands with diagnostic copy number variants, 32 probands with secondary findings, and 31 probands with multiple molecular diagnoses. Reanalysis added 22 molecular diagnoses, predominantly due to new disease-gene associations (9 of 22, 40.9%). One-quarter of the molecular diagnoses (92 of 361) did not involve immune-associated genes. Molecular diagnosis was correlated with younger age, male sex, and a higher number of organ systems involved. This program also facilitated the discovery of new gene-disease associations such as SASH3-related immunodeficiency. A review of treatment options and ClinGen actionability curations suggest that at least 251 of 361 of these molecular diagnoses (69.5%) could translate into ≥1 management option.CONCLUSIONS:This program contributes to our understanding of the diagnostic and clinical utility whole exome analysis on a large scale.

On the 25th of July, disheartening news of the untimely demise of our distinguished colleague and dear friend, John Bienenstock, reached the immunological community and was profoundly felt by mucosal immunologists. Undoubtedly, Dr. Bienenstock is one of the universally acknowledged founders of the discipline of mucosal immunology, together with several current colleagues and the recently deceased Drs. Per Brandtzaeg and Lars Ǻ Hanson. Recognition of the mucosal immune system as an integral, and perhaps the dominant component, of the entire immune system is based on quantitative studies of B and T cells as well as antibody-producing cells in mucosal lymphoid tissues. In the mid 1960's, John Bienenstock, burst into the immunological scene as a mucosal immunologist with a series of groundbreaking studies that convincingly demonstrated the integral interactions of individual components of the mucosal immune system and defined the latter's inductive and effector sites. This culminated a decade later (1974) in a foundational study of mucosal immunity in which Dr. Bienenstock showed that cells in bronchial lymphoid aggregations (BALT) could function in a similar manner to cells in Peyer's patch lymphoid aggregations (GALT) in their ability to repopulate other parts of the mucosal immune system. Thus, for the first time Bienenstock (and ultimately the rest of the immunologic community) could envision a Common Mucosal Immune System (so-named by Bienenstock) that was both a unique and vital part of the immune system as a whole. Even today, almost half a century later, this work is remembered (and cited) in our attempt to understand the immunopathology of the SARS-CoV-2 infection, an infection that initially invades the upper respiratory tract and lung tissue but can spread via routes defined by the migration of cells in the mucosal immune system. However, John Bienenstock's contributions to mucosal immunology didn't stop there. In the ensuing years he and the groups of investigators he led continued to provide impressive studies establishing the structure and production of polymeric secretory IgA, the definition of inductive and effector mucosal sites and their associated histological features, the presence of distinct phenotypes of cells in mucosal compartments, and the induction of immune responses ensuing after a variety of immunization routes. In addition, in recent years the broad yet deep knowledge of mucosal immunity this work encompasses allowed him to pursue difficult questions concerning the neurological regulation of the mucosal immune system and the impact of mucosal microbiota on the mucosal system. Overall, the continued excellence of the research embodied in these studies led to his well-deserved designation as one of the most brilliant and impactful scientists in the field of mucosal immunology. Those of us who were privileged to know John as a close, personal friend will remember his unforgettable charm as well as his witty, entertaining and generous cast of mind. At numerous meetings, he displayed not only an impressive knowledge of immunology but also a deep understanding of a broad spectrum of scientific and cultural conundrums. John's astute intellect generated a continuous stream of insightful questions and solutions as well. For this reason among others, he was an indispensable member of the early and relatively small group of mucosal immunologists establishing the field of study. John's conception of scientific life extended beyond the actual performance of science. This took the form of his prominent role in the organization of many national and international conferences, including those in Canada, the United States, and many European countries. Some of these meetings were sponsored by the Mucosal Immunity Society, and John was in fact an early organizer of the Society and its second President. In addition, he was the co-editor of the “Proceeding of International Meetings of Mucosal Immunologists” published in the Advances of Experimental Medicine and Biology, and more importantly, the co-editor of first two editions of Mucosal Immunology book published by Academic Press/Elsevier. All the while he was the sponsor and advisor to countless graduate students, post-doctoral fellows, and national and international visitors who worked in his laboratory. John was born in Hungary but his family immigrated to England in the late 1930's and John received his college and medical education in that country. After initial scientific training as a post-doctoral Fellow at Harvard, he began his lifelong career as a mucosal immunologist by working at the University of Buffalo under the guidance of Thomas Tomasi, the “father” of mucosal immunology. Then, having already established himself as a leader in mucosal immunology, he moved to MacMaster University where planted his feet and stayed on as one of the intellectual and administrative leaders of this major Canadian educational institution. Among the positions he held at MacMaster was Distinguished University Professor of Pathology and Molecular Medicine, Chair of Pathology and Vice president and Dean of the Faculty of Health Sciences. In addition, in a related position he has recently served as Director of the Brain and Body Institute at St. Joseph's Health Care in Hamilton, Canada. John's productive career and excellence was recognized by many awards including an Honorary Degree of Doctor of Medicine, Goteborg University, Sweden, the MacMaster Community Distinction Award, election to the Canadian Medical Hall of Fame, the Order of Canada from the Canadian government, the designation as a Distinguished University Professor at MacMaster University, and the designation as Distinction as the Fellow of the Royal Society of Canada. John is survived by his wife for over 60 years, Dr. Audrey (Dody) Sanders, herself a remarkable scholar and physician who served as the president of the Royal College of Physicians and Surgeons of Canada. In addition to his exceptional scholarly achievements, we will remember John as a kind, caring, and generous friend who brought pleasure and inspiration to all of us. We shall miss him greatly. The authors declare no competing interests.