Gut ischemia/reperfusion (I/R) causes distant organ dysfunction, including brain injury, through gut-brain crosstalk. Here, we discovered a novel subset of neutrophils (CD40L⁺ PMNs) that accumulates in both the gut and brain following intestinal I/R. We hypothesized that these CD40L⁺ PMNs are primed in the gut by B cell-expressed OX40L and subsequently migrate to the brain, where they activate microglia and promote brain dysfunction. Intestinal I/R was induced in C57BL/6 mice by superior mesenteric artery occlusion for 30 min followed by reperfusion. Brain infiltration of CD40L⁺ PMNs and microglial TNFα production were assessed. In vitro co-cultures of brain neutrophils with BV2 microglia (± anti-CD40L antibody) and bone marrow-derived neutrophils with B cells (± anti-OX40L antibody) elucidated the mechanisms underlying CD40L⁺ PMN function and generation. Mesenteric lymph duct ligation (MLDL) was used to examine CD40L⁺ PMNs trafficking, and adoptive transfer of CD40L-blocked neutrophils followed by open-field and Y-maze testing evaluated neurological outcomes. Intestinal I/R markedly increased CD40L⁺ PMN infiltration into the brain and enhanced microglial TNFα production, both of which were attenuated by neutrophil depletion. CD40L-dependent microglial activation was confirmed in vitro. Brain CD40L⁺ PMNs originated from Peyer’s patches, as MLDL reduced their brain accumulation, and their generation required B cell OX40L. Importantly, blockade of CD40L on neutrophils reduced anxiety-like behavior and preserved working memory after intestinal I/R. These findings identify B cell OX40L-induced CD40L⁺ PMNs as a key mediator of gut-brain inflammation and a promising therapeutic target for I/R-induced brain dysfunction.
Molecular studies have clarified the causes of vascular malformations and enabled targeted treatment. The broad phenotypic variation associated with variants in the same gene, however, complicates translation of molecular findings into clinical decisions. This narrative review examines genotype–phenotype relationships and their implications for diagnosis, treatment, and outcome assessment. PI3K–AKT–mTOR alterations are common in venous, lymphatic, and overgrowth disorders, while RAS–MAPK alterations are frequent in arteriovenous malformations. Gαq/11 signaling is implicated in capillary and neurocutaneous malformations, while distinct mechanisms underlie hereditary hemorrhagic telangiectasia and cerebral cavernous malformations. Within these groups, variant function and the distribution of variant-bearing cells may contribute to phenotypic variation. Clinical phenotype and suspected variant distribution guide initial specimen selection. Molecular findings then inform family testing and surveillance. Treatment decisions begin with disease extent, symptoms, organ risk, and patient goals; genotype then helps inform systemic-agent selection. Clinical evidence is most extensive for sirolimus in complicated slow-flow anomalies and alpelisib in severe PIK3CA-related overgrowth, although study designs and response definitions differ. Benefit is assessed through imaging, symptoms, function, organ-specific measures, patient-reported outcomes, and adverse effects. Integrating molecular findings with tissue involvement and clinical burden can refine diagnosis, surveillance, and treatment decisions. Improving prediction for individual patients requires prospective studies with consistent molecular characterization, clinically meaningful outcomes, and long-term safety follow-up.
Keloids and hypertrophic scars (HS) share fibrotic repair programmes but differ in growth beyond wound boundaries and their tendency to regress. Single-cell and spatial studies can help explain how similar cellular programmes produce different tissue outcomes. This narrative review compares human scar studies with mechanistic experiments. POSTN-richfibroblast states recur in keloids and HS, but their spatial distributions differ between studies: dispersedmesenchymal fibroblasts in one keloid study contrast with deep, vessel-associated signals in another. Thesefindings support a shared matrix-producing programme more strongly than a uniform anatomical compartment.We define multicellular niches as local tissue microenvironments and distinguish their observed organisationfrom hypotheses about their function. A candidate fibrovascular niche comprises activated fibroblasts andnearby endothelial cells in deep keloid dermis; the hypothesis is that local signalling sustains matrixproduction and vascular activation. Neural–stromal studies instead link fibroblast–Schwann-cellcommunication to itch and pain. Experiments connect PIEZO1-dependent calcium entry to YAP activity inkeloid fibroblasts, epidermal FOSL1–MED1 regulation to MMP3-dependent fibroblast activation, andmacrophage-derived lactate to MCT1-dependent fibroblast responses in HS. Shared matrix-producing fibroblast programmes occur in both scar types, while spatial studies report different tissue arrangements. Functional experiments identify mechanical, epidermal and metabolic inputs to profibrotic activity. How these inputs are organised locally and contribute to persistent growth or symptoms remains to be established.
Intercellular communication mediated by Extracellular Vesicles (EVs), including small EVs (sEVs) and exosomes, is systematically used by viruses, such as the Hepatitis C Virus (HCV), for establishing viral infection, spread and persistence through immune system deregulation. HCV causes severe liver disease. Direct-acting antivirals (DAAs) eradicate the virus, but host immunity fails to fully recover. To investigate the role of HCV-associated sEV cargo in the immune response of chronic Hepatitis C (CHC) patients with characterised liver fibrosis, pre- and post-DAA treatment, we isolated serum EVs and peripheral blood mononuclear cells (PBMCs) from these patients. Nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) determined EV size/concentration and shape, respectively. sEV cargo was analysed for the presence of immunosuppressive factors transforming growth factor-β (TGF-β) and programmed death-ligand 1 (PD-L1) by immunoblotting and enzyme-linked immunosorbent assays (ELISA). Our data showed that DAA treatment reduced the HCV-mediated increase in sEV-TGF-β from mild to advanced fibrosis. sEV-PD-L1 expression was up-regulated from mild fibrosis to advanced fibrosis and cirrhosis and remained elevated irrespectively of DAA administration. PBMC phenotyping, performed by flow cytometry, revealed unchanged levels of cytotoxic T-cells in all conditions examined. Furthermore, the regulatory T-cells (Tregs) were decreased significantly in mild fibrosis, but they were found expanded in advanced fibrosis and cirrhosis after DAA treatment, compared to infected controls. Multiple linear regression models revealed a strong reciprocal relationship between Tregs and sEV-PD-L1 levels. Overall, our data suggest an intricate interplay between Tregs and sEV-PD-L1, which could assist with the maintenance of an immune suppression state and chronic tissue remodelling in CHC patients. Post-treatment, this remaining immunosuppressive viral signature could deteriorate liver disease in patients with advanced fibrosis and cirrhosis, possibly promoting the development or progression of hepatocellular carcinoma (HCC) in susceptible individuals cured of HCV.
The progression of osteoarthritis (OA), a degenerative joint disease, is closely associated with dysregulated inflammatory and catabolic signaling, in which nuclear factor-kappa B (NF-κB) plays a central role. Although casein kinase 2 (CK2) is a major NF-κB regulator, the specific role of subunit CK2β in OA pathogenesis remains unclear. Here, we aimed to investigate the role of CK2β regulation in OA progression. CK2β expression and CK2 kinase activity were examined in cartilage obtained from patients with OA by immunohistochemistry and kinase activity assays. In vitro CSNK2B knockdown was performed in tumor necrosis factor alpha-stimulated human chondrocytes to evaluate inflammatory and catabolic gene expression. The role of CK2β in vivo was further investigated using cartilage-specific Csnk2b conditional knockout mice after destabilization of the medial meniscus (DMM) surgery. In addition, the effect of CK2 inhibition with CX-4945 was evaluated in both DMM- and monosodium iodoacetate (MIA)-induced OA models. CK2β expression and CK2 kinase activity were increased in damaged regions of human OA cartilage compared with relatively intact regions. Phosphorylation of p65 and IκB was also higher in damaged cartilage, indicating enhanced NF-κB signaling. Under inflammatory conditions, CK2β was associated with components of the NF-κB pathway. Knockdown of CSNK2B reduced IκBα ubiquitination and NF-κB transcriptional activity and decreased the expression of inflammatory and cartilage-degrading factors. At the same time, cartilage-related marker expression was partially preserved. In mice, cartilage-specific deletion of Csnk2b reduced cartilage degeneration after DMM surgery and was accompanied by lower NF-κB-associated signaling. Pharmacological CK2 inhibition with CX-4945 reduced cartilage damage in both DMM and MIA models and partially improved OA-associated functional changes. These findings identify CK2β as a disease-associated regulator of inflammatory and catabolic signaling in OA and support pharmacological CK2 inhibition as a potential strategy to attenuate cartilage degeneration.
