In the last twenty years Leucine Rich Repeat Kinase 2 (LRRK2) has received immense attention due to its association with several diseases, for example, neurodegenerative disease PD (Parkinson’s Disease), inflammatory bowel disease (IBD), Crohn’s disease (CD), infectious disease Leprosy etc. Not only do genetic mutations make this protein a hotspot for various diseases but also it shows some pleotropic characteristics which might influence several diseases. LRRK2 directly controls several proteins for example Rab GTPase proteins, NLRC4 inflammasomes etc. NLRC4 also showed correlation with auto-inflammatory diseases such as CD, Macrophage Activation Syndrome (MAS) etc. Here we report that NLRC4 dependent cytokine storm retarded through LRRK2 kinase inhibition as well as reduces severity of intestinal inflammation. For LRRK2 kinase inhibition a novel kinase inhibitor (Termed CS 82) has been used. In vitro studies disclosed that this inhibitor 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. LRRK2 deficiency showed inhibitor has no effect on NLRC4 dependent IL-1b cytokine productions. These findings suggest that inhibition of LRRK2 kinase activity retarded NLRC4 inflammasome activation which reduces IL-1b cytokine productions and intestinal inflammation severity.

In this issue of Cellular and Molecular Gastroenterology and Hepatology, Zhong et al1Zhong X.S. Winston J.H. Luo X. Kline K.T. Nayeem S.Z. Cong Y. Savidge T.C. Dashwood R.H. Powell D.W. Li Q. Neonatal colonic inflammation epigenetically aggravates epithelial inflammatory responses to injury in adult life.Cell Mol Gastroenterol Hepatol. 2018; 6: 65-78Abstract Full Text Full Text PDF Scopus (16) Google Scholar reported that colonic inflammation induced in neonatal rats by intrarectal administration of trinitrochlorobenzene (TNBS) results in more severe colitis after TNBS administration 6–8 weeks later (relative to rats that did not experience neonatal TNBS colitis). They thus concluded that during early life the organism can be imprinted to mount exaggerated inflammatory responses, which persists for a relatively long period of time. Studies to analyze the basis of the imprinting showed that neonatal rats with gut inflammation released norepinephrine/epinephrine into the circulation and the latter caused epigenetic changes in the interleukin 1β promoter (and perhaps other promoters). These changes, characterized by increased acetylation of histone H4K12, led to increased accessibility of the interleukin 1β promoter to binding of RelA, a nuclear factor-κB component that promotes gene transcription. The investigators thus suggested that substances that are part of the stress response (eg, norepinephrine or epinephrine) caused by the neonatal inflammation induce long-term hyperactivity of proinflammatory genes that, in turn, increase inflammatory responses when the animal is again exposed to factors inducing inflammation (in this case a second exposure to TNBS). The results are striking, but do leave important questions unanswered. For example, how long do the epigenetic changes persist and are norepinephrine or epinephrine the only factors capable of inducing these changes? The clinical implications of these findings, that gut inflammation occurring early in life can be a risk factor for inflammation occurring much later, are important. Nevertheless, it is not entirely clear how they relate to human disease. Although inflammatory bowel disease (IBD) can occur early in life as a persistent illness, enterocolitis has not been reported as a harbinger of severe IBD when occurring as an isolated incident during childhood, as might be predicted by these studies. Similarly, although there are some reports suggesting that infection of the gastrointestinal (GI) tract in early life occurs with a higher frequency in IBD patients, these reports, taken together, have not established a clear etiologic role for early infection in IBD pathogenesis. Along these lines there is no credible evidence that measles virus infection or live (attenuated) virus vaccination early in life is a precursor of IBD.2Robertson D.J. Sandler R.S. Measles virus and Crohn's disease: a critical appraisal of the current literature.Inflamm Bowel Dis. 2001; 7: 51-57Crossref PubMed Scopus (41) Google Scholar, 3Shaw S.Y. Blanchard J.F. Bernstein C.N. Early childhood measles vaccinations are not associated with paediatric IBD: a population-based analysis.J Crohns Colitis. 2015; 9: 334-338Crossref PubMed Scopus (8) Google Scholar Although no clinical data support early effects of inflammation on subsequent IBD development, it remains possible that interactions of the neonatal immune system with microbes in the neonatal GI tract do influence susceptibility to IBD or chronic inflammation of other organs, such as the lungs in asthma. Evidence supporting this idea has come from studies showing that germ-free mice develop increased numbers of natural killer T (NKT) cells in their colons that, in turn, results in more severe ulcerative colitis–like inflammation when these mice are colonized by conventional microflora and challenged with intrarectal oxazolone (oxazolone colitis).4Olszak T. An D. Zeissig S. et al.Microbial exposure during early life has persistent effects on natural killer T cell function.Science. 2012; 336: 489-493Crossref PubMed Scopus (1186) Google Scholar This increased intestinal inflammation could be prevented by colonization of germ-free neonatal, but not germ-free adult, mice with conventional gut microbiota. Thus, the neonatal immune system provides a window of opportunity during which the propensity to increased gut inflammation can be reversed. Additional studies have indicated that increased secretion of CXC motif chemokine with Ligand 16 (CXCL16) drives NKT cell chemotaxis to, and accumulation in, colonic tissues. Increased CXCL16 secretion was caused by cells with epigenetic changes that increased CXCL16 gene transcription in the germ-free gut. Interestingly, NKT cell expansion in germ-free mice could be reversed in neonatal, but not adult, germ-free mice by colonization with Bacteroides fragilis organisms expressing a particular glycosphingolipid, termed Bf717.5An D. Oh S.F. Olszak T. et al.Sphingolipids from a symbiotic microbe regulate homeostasis of host intestinal natural killer T cells.Cell. 2014; 156: 123-133Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar The older data relating to NKT cells and oxazolone colitis are similar to the present study of neonatal and recurrent TNBS colitis in that both were driven by persistent genetic changes induced in the neonatal period. Zhong et al1Zhong X.S. Winston J.H. Luo X. Kline K.T. Nayeem S.Z. Cong Y. Savidge T.C. Dashwood R.H. Powell D.W. Li Q. Neonatal colonic inflammation epigenetically aggravates epithelial inflammatory responses to injury in adult life.Cell Mol Gastroenterol Hepatol. 2018; 6: 65-78Abstract Full Text Full Text PDF Scopus (16) Google Scholar point to a number of studies providing evidence that components of the genome are uniquely susceptible to epigenetic changes, such as DNA methylation and histone acetylation, in neonates. These changes can have long-term effects on gene expression that lead to the development of a variety of diseases, including diseases of the GI tract.6Winston J.H. Sarna S.K. Developmental origins of functional dyspepsia-like gastric hypersensitivity in rats.Gastroenterology. 2013; 144: 570-579 e3Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar Determination of whether this is an important influence on IBD development awaits further work. Neonatal Colonic Inflammation Epigenetically Aggravates Epithelial Inflammatory Responses to Injury in Adult LifeCellular and Molecular Gastroenterology and HepatologyVol. 6Issue 1PreviewEarly life adversity is considered a risk factor for the development of gastrointestinal diseases, including inflammatory bowel disease. We hypothesized that early life colonic inflammation causes susceptibility to aggravated overexpression of interleukin (IL)1β. Full-Text PDF Open Access

This chapter summarizes the evidence obtained from human trials that parenteral immunization produces clinically significant protection against infections that begin at the mucosal surface and cause mucosal and/or systemic disease. The data available come primarily from trials directed toward infections of the respiratory and gastrointestinal tracts. Few human data are available for other sites, such as the genitourinary tract, with emerging evidence that the parenteral approach can be effective in reducing infection and disease in the genitourinary tract. Development of vaccines for administration via mucosal routes (e.g., oral, nasal) has been a major goal of academic and industrial-based researchers for the past few decades. Mucosally administered vaccines are of particular interest for application against infectious agents that cause disease at mucosal sites, and they may also have application against systemic infection and disease. Although mucosally administered vaccines have advanced closer to the clinic, there may still be a place for achieving systemic and mucosal protection with vaccines administered parenterally. A review of the evidence obtained from human clinical trials suggests that parenteral immunization may provide significant protection at mucosal surfaces and against systemic disease. The purpose of this chapter is to review the data from human trials that describe the mucosal immune response to parenteral immunization and, in particular, the evidence that parenteral immunization affects clinical outcome at mucosal sites.

The understanding of the intestinal inflammation occurring in the inflammatory bowel diseases (IBD) has been immeasurably advanced by the development of the now numerous murine models of intestinal inflammation. The usefulness of this research tool in IBD studies has been enabled by our improved knowledge of mucosal immunity and thus our improved ability to interpret the complex responses of mice with various causes of colitis; in addition, it has been powered by the availability of models in which the mice have specific genetic and/or immunologic defects that can be related to the origin of the inflammation. Finally, and more recently, it has been enhanced by our newly acquired ability to define the intestinal microbiome under various conditions and thus to understand how intestinal microorganisms impact on inflammation. In this brief review of murine models of intestinal inflammation, we focus mainly on the most often used models that are, not incidentally, also the models that have yielded major insights into IBD pathogenesis. Keywords: Cell Transfer Colitis, DSS Colitis, IL10 Deficiency, Murine Colitis Models, NKT Cells, Oxazolone Colitis, TNBS Colitis, TH1 Cells, TH17 Cells, Tregs

Some clinical trials and epidemiologic studies revealed improvements in symptoms of ulcerative colitis after smoking and nicotine patch treatment. However, mechanisms underlying the ameliorating effect of nicotine remain poorly understood. We have previously reported that nicotine administration ameliorates murine oxazolone (OXZ)-induced colitis through alpha7 nicotine acetylcholine receptors (α7nAChRs). In addition, we have shown that mRNA of α7nAChRs was expressed in plasmacytoid dendritic cells (pDCs) of OXZ colitis mouse colon. The aim of this study was to investigate a pathophysiological role of pDCs and immunological effects of nicotine on pDCs in ulcerative colitis. Method: OXZ-induced colitis was developed in BALB/c mice. Lamina propria mononuclear cells (LPMCs) of the colon and mesenteric lymph node (MLN) were collected in OXZ colitis mice. pDCs were isolated from LPMCs by using magnetic cell separation system (BD biosciences). In addition, mouse bone marrow (BM) cells were differentiated to pDC-like cells (BMpDC) by Flt3 ligand. Furthermore, immunological effects of nicotine on BMpDCwere examined by flow cytometry and BMpDC migration was examined by chemotaxis assay using EZ-TAXIScan. Moreover, the effect of nicotine administration on pDC subset proportion was investigated in the MLN of OXZ colitis mice. Result: α7nAChRs mRNA was expressed in pDC of OXZ colitis mouse colon and BMpDC, but not BM conventional dendritic cells (cDC). Flow cytometry analysis revealed that neither CD80, CD86 nor MHC class II expression in BMpDC was affected with nicotine in the induction of pDC maturation by CpG-DNA. On the other hand, CCL21induced migration of mature BMpDC was inhibited by nicotine and α7nAChRs selective agonist GTS-21, and α7nAChRs selective antagonist methyllycaconitine (MLA) blocked the inhibitory effect of nicotine and GTS-21. Furthermore, nicotine administration downregulated pDC subset proportion in the MLN of OXZ colitis mice. Conclusion: These data suggest that the activation of α7nAChRs reduces pDC-mediated antigen presentation to naive CD4 T cells by inhibiting pDC migration from colon to MLN, thereby alleviating the symptoms in OXZ colitis. Our results may contribute to the development of therapeutic medicines for ulcerative colitis by activating the cholinergic anti-inflammatory pathway.

X-linked hyper IgM syndrome (XHM) is a combined immune deficiency disorder caused by genetic alterations in CD40 ligand. The purpose of this study was to investigate the safety and efficacy of recombinant CD40 ligand (rCD40L) in the treatment of the disease. Three children were administered rCD40L subcutaneously 3 times per week at 0.03 mg/kg for 22 weeks, and after a 12-week drug-free interval, the dose was increased to 0.05 mg/kg for an additional 22 weeks of treatment. Although specific antibody responses to T cell-dependent antigens was lacking, administration of rCD40 resulted in acquisition of the capacity to mount cutaneous delayed type hypersensitivity reactions that disappeared during the drug-free interval as well as the postbiologic follow-up period. With rCD40L treatment, patient T cells developed a new capacity to respond to T-cell mitogens with synthesis of IFN-γ and TNF-α. Intracellular cytokine staining studies showed that both CD4(+) and CD8(+) T cells participated in this response. Finally, CD40L therapy was associated with changes in lymph node size and architecture based on comparison of biopsies taken before and after therapy. This clinical study showed that rCD40L is capable of improving T cell-immune function in patients with XHM.

This discussion followed talks by Andrew Caton, Warren Strober, Fiona Powrie, Manuela Battaglia, and Richard Blumberg on various aspects of regulatory cell function. Meeting organizer Lloyd Mayer kicked off the session by pointing out that regulatory cells form a large grouping. Rather than comprising just one population, there is a wide panoply of regulatory cells in the body. Mayer posed a series of questions to the panel: Is there crosstalk between different types of regulatory cells? Which are most important? Are there organ specificities? Are there unique features about the ways in which investigators are activating/isolating regulatory cells in vitro or in vivo that obscure their real function in vivo? Although much current interest is focused on regulatory CD4+CD25+ T cells, Mayer pointed out that depletion of these “natural” CD4+CD25+ regulatory T (Treg) cells by neonatal thymectomy leads to autoimmune gastritis, not colitis or other forms of autoimmunity, suggesting organ specificity in Treg cell generation and/or function. Mayer asked each of the session’s speakers to attempt to describe their view of the particular type of regulatory cell they study in its in vivo context. Manuela Battaglia said that Tr1 are antigen specific, and are induced in the periphery after chronic exposure to antigen in the presence of IL-10. Tr1 can be generated from CD25− T cells but it is not known if they talk to, or are dependent on, CD25+ T cells. By contrast, CD4+CD25+ T cells are natural noninduced Treg cells that are present at birth. Warren Strober agreed with Dr. Battaglia and emphasized that, in most instances, Tr1 cells are induced by exogenous microbial antigen and generated locally, not at the level of the thymus. By contrast, CD4+CD25+ Treg cells are directed at self-

E lucidation of the immunologic features of HIV infection has, for a variety of compelling reasons, become one of the most important areas of immunological research. It is essential to realize, however, that such research is not just of interest to the relatively small group of immunologists who are directly engaged in it; on the contrary, the effects of HIV on the immune system are so profound that in learning about the response to HIV infection we obtain new information about basic mechanisms affecting all immune responses.

Antibodies to tumor necrosis factor (TNF)‐α have been recently proposed as effective treatment for patients with Crohn's disease. Here, we analyze the functional role of TNF‐α in a mouse model of chronic intestinal inflammation induced by the hapten reagent 2,4,6,‐trinitrobenzene sulfonic acid (TNBS) that mimics some characteristics of Crohn's disease in humans. Macrophage‐enriched lamina propria (LP) mononuclear cells from mice with TNBS‐induced colitis produced 10–30‐fold higher levels of TNF‐α mRNA and protein than cells from control mice. When mice with chronic colitis were treated by intraperitoneal injection of antibodies to TNF‐α, an improvement of both the clinical and histopathologic signs of disease was found. Isolated macrophage‐enriched LP cells from anti‐TNF‐α‐treated mice produced strikingly less pro‐inflammatory cytokines such as interleukin (IL)‐1 and IL‐6 in cell culture. The predominant role of TNF‐α in the mouse TNBS‐induced colitis model was further underlined by the finding that striking colonic inflammation and lethal pancolitis was induced in TNF‐α‐transgenic mice upon TNBS treatment. Conversely, no significant TNBS‐induced colitis could be induced in mice in which the TNF‐α gene had been inactivated by homologous recombination. Complementation of TNF‐α function in TNF −/− mice by the expression of a mouse TNF‐α transgene was sufficient to reverse this effect. Taken together, the data provide direct evidence for a predominant role of TNF‐α in a mouse model of chronic intestinal inflammation and encourage further clinical trials with antibodies to TNF‐α for the treatment of patients with Crohn's disease.