Th1 cells contribute to retinal ganglion cell loss in glaucoma in a VCAM-1-dependent manner.

Glaucoma is a complex neurodegenerative disorder characterized by the progressive loss of retinal ganglion cells (RGC) and optic nerve axons, leading to irreversible visual impairment. Despite its clinical significance, the underlying mechanisms of glaucoma pathogenesis remain poorly understood. In this study, we aimed to unravel the multifaceted nature of glaucoma by investigating the interaction between T cells and retinas. By utilizing clinical samples, murine glaucoma models, and T cell transfer models, we made several key findings. Firstly, we observed that CD4+ T cells from glaucoma patients displayed enhanced activation and a bias towards T helper (Th) 1 responses, which correlated with visual impairment. Secondly, we identified the infiltration of Th1 cells into the retina, where they targeted RGC and integrated into the pro-inflammatory glial network, contributing to progressive RGC loss. Thirdly, we discovered that circulating Th1 cells upregulated vascular cell adhesion protein 1 (VCAM-1) on retinal microvessels, facilitating their entry into the neural retina. Lastly, we found that Th1 cells underwent functional reprogramming before reaching the retina, acquiring a phenotype associated with lymphocyte migration and neurodegenerative diseases. Our study provides novel insights into the role of peripheral CD4+ T cells in glaucoma pathogenesis, shedding light on the mechanisms underlying their infiltration into the retina and offering potential avenues for innovative therapeutic interventions in this sight-threatening disease.

Fecal calprotectin as an intestinal inflammation marker is elevated in glaucoma.

Objective: The aim of this study was to investigate the potential association between glaucoma and fecal calprotectin. Methods: A total of 144 glaucomatous patients and 66 healthy controls were enlisted for this study. The fecal calprotectin was assessed using enzyme-linked immunosorbent assay. Results: The median fecal calprotectin levels were significantly elevated in glaucoma (73.67 vs 41.97 µg/g; p < 0.001), primary angle-closure glaucoma (76.85 µg/g; p < 0.001) and primary open-angle glaucoma (69.29 µg/g; p = 0.016) groups compared with controls. A notable proportion of the glaucoma (24%; p < 0.001), primary angle-closure glaucoma (21%; p < 0.001) and primary open-angle glaucoma (24%; p < 0.001) subgroups exhibited highly abnormal fecal calprotectin levels (≥250 µg/g). Conclusion: Elevated fecal calprotectin might indicate potential intestinal inflammation in glaucoma.

Gut-licensed ß7+ CD4+ T cells contribute to progressive retinal ganglion cell damage in glaucoma.

Glaucoma is the leading cause of irreversible blindness. Currently, most therapeutic strategies aim to reduce elevated intraocular pressure (EIOP), but this does not always halt disease progression. Evidence suggests a role for T cells in glaucoma pathogenesis, but the underlying mechanisms remain largely unknown. Here, we found that the percentage of circulating CD4+ T cells expressing a gut-homing integrin ß7 was increased in patients with glaucoma and was associated with disease stage. In an EIOP-triggered glaucoma mouse model, ß7+ CD4+ T cells infiltrated the retina in the progressive phase of glaucoma via eliciting retinal endothelial cell expression of mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1). MAdCAM-1 was minimally detected in retinas of healthy mice, and neutralization with an MAdCAM-1 antibody ameliorated retinal ganglion cell (RGC) loss and glial activity in mice with glaucoma. We furthermore found that EIOP-induced ß7+ CD4+ T cells homed to the gut during the acute phase of glaucoma, which was essential for progressive RGC damage in diseased mice. Gut-homing ß7+ CD4+ T cells underwent transcriptional reprogramming, showing up-regulated pathways enriched in autoimmune diseases, bacteria responses, mucosal immunity, and glial activity. Gut-homing ß7+ CD4+ T cells gained the competence to induce retinal MAdCAM-1 expression and to cross the blood-retina barrier. Together, our study reveals a role of gut-licensed ß7+ CD4+ T cells and MAdCAM-1 in RGC degeneration and emphasizes the importance of the "gut-retina" axis in glaucoma.

CO2 Is Beneficial to Gut Microbiota Homeostasis during Colonoscopy: Randomized Controlled Trial.

BACKGROUND: Many studies have reported minor complications and disturbance of the gut microbiota after colonoscopy. Compared with air, carbon dioxide (CO2) insufflation could decrease minor complications, but its impact on gut microbiota remains unknown. METHODS: Thirty-eight healthy subjects were assessed and twenty were randomized to receive either CO2 or air insufflation during colonoscopy. Neither the participants nor the staff involved in the follow-up knew which gas was used. Minor complications were assessed using symptom scores. Fecal samples were collected at eight time-points for microbiome analysis by full-length 16S rRNA gene amplicon analysis. RESULTS: Baseline characteristics were similar in both groups. The recovery of minor complications after colonoscopy was faster in the CO2 group (the day of the colonoscopy) than in the air group (the day after the colonoscopy). There was no significant reduction in alpha diversity (species richness) of the first stool after colonoscopy in the CO2 group (115.0 ± 32.81 vs. 97.4 ± 42.31, p = 0.28) compared with the air group (123.8 ± 37.25 vs. 84.8 ± 31.67, p = 0.04). However, there were no differences in beta diversity between the groups. Linear discriminant analysis effect size (LEfSe) analysis indicated that anaerobic probiotics such as Bacteroides caccae, Bacteroides finegoldii and Bacteroides thetaiotaomicron were more abundant in the CO2 group than in the air group within 14 days after colonoscopy. On the contrary, the content of Escherichiacoli, Ruminococcus torques and Ruminococcus guavus was higher in the air group. CONCLUSIONS: CO2 is beneficial to gut microbiota homeostasis during colonoscopy in healthy subjects. The effects in patients with different diseases need to be further studied.

The Flavonoid Kurarinone Regulates Macrophage Functions via Aryl Hydrocarbon Receptor and Alleviates Intestinal Inflammation in Irritable Bowel Syndrome.

BACKGROUND: Irritable bowel syndrome (IBS) is characterized with abdominal pain, bloating, and changes in bowel habits, and dealing with IBS is still a clinical challenge. The pathogenesis of IBS has been reported to be linked to low-grade mucosal inflammation, and macrophages contribute to the pathological process of this disease. Kurarinone (KAR), a flavanoid derived from Sophora flavescens, has been found medically effective in many inflammatory conditions and cancers. KAR was previously reported to inhibit LPS-induced expression of inflammatory cytokines in macrophages, whether and how KAR regulates the functions of macrophage in IBS remains to be elusive. METHODS: We established a TNBS-induced IBS mouse model, in which KAR was administrated, and mucosal cytokine expression was measured by qRT-PCR. Additionally, mouse macrophages were generated in vitro and their responses to LPS were evaluated by flow cytometry and qRT-PCR. AhR+/+ or AhR-/- macrophages were transferred into DTx-treated CD11b-DTR transgenic mice to investigate the role of AhR in IBS. We collected colonic biopsies and peripheral blood samples from 64 patients with IBS, and analyzed AhR expression by qRT-PCR. RESULTS: We found KAR effectively alleviated visceral hypersensitivity and maintained intestinal barrier functions in mice with IBS. KAR inhibited LPS-induced macrophage activation and expression of pro-inflammatory genes, while increased anti-inflammatory gene expression including IL-10 in an AhR-dependent manner. Using macrophage-depleted mice, we found that chimera mice with AhR-/- macrophages were more susceptible to TNBS-induced IBS and the therapeutic effect of KAR on IBS was significantly impaired in mice with AhR-/- macrophages. Additionally, we found AhR expression in macrophages of IBS patients was associated with the disease severity. CONCLUSION: Our findings provide new evidences that KAR regulates IBS development via macrophage-intrinsic AhR. KAR might show promise as an immunomodulatory therapeutic agent in treating IBS.

Alterations in Peripheral B Cell Subsets Correlate with the Disease Severity of Human Glaucoma.

BACKGROUND: Glaucoma is a group of retinal neurodegenerative diseases causing irreversible visual impairment. The pathogenesis of this disease is complicated. Studies have shown that the immune system is involved in the neurodegenerative process of glaucoma. There are continuous evidences that autoantibodies play a crucial role in the pathogenesis of glaucoma. However, focuses on B cells, the antibody-producing cells in glaucoma are surprisingly limited. METHODS: Fresh peripheral blood samples were collected from 44 glaucoma patients (38 with primary angle-closure glaucoma (PACG) and 6 with (primary open-angle glaucoma POAG)) and 36 age-matched healthy donors (HD). Density gradient centrifugation was performed to obtain peripheral blood mononuclear cells (PBMC). Flow cytometry was performed to determine B cell phenotypes. The severity of glaucoma was determined based on the mean deviation (MD) of visual field. RESULTS: In this study, we demonstrated that total B cells was significantly increased in glaucoma patients compared to HD. Next, we checked changes of different B cell subsets in glaucoma. Glaucoma patients were found to have a significant increase in the frequencies of antibody-secreting cells (ASC)/plasmablasts, naïve, and CD19+ CD27- IgD- double negative (DN) subpopulations, but a decrease in the CD27+ IgD+ unswitched memory compartment. Notably, we found that the increment of CD27- IgD- DN B cells was significantly magnified according to the clinical severity. CONCLUSION: We demonstrate, for the first time, that peripheral B cell subsets are altered and unveil the correlation of a newly identified pro-inflammatory CD27- IgD- DN subset with clinical features of glaucoma, suggesting that these B cell subsets could serve as potential biomarkers to monitor the disease progression of glaucoma patients.

MAdCAM-1 mediates retinal neuron degeneration in experimental colitis through recruiting gut-homing CD4+ T cells.

Extra-intestinal manifestations (EIMs) of the eyes are found in IBD patients, but the underlying pathogenesis remains unknown. To investigate the pathogenesis of IBD-associated retinal dysfunction, chronic colitis was induced in mice by oral administration of dextran sodium sulfate (DSS). Electroretinography (ERG) was performed to evaluate retinal function. Retinal neuron degeneration was analyzed by immunohistochemistry. Colitic mice displayed aberrant amplitudes of ERG a-, b-wave and oscillatory potentials (OP). Importantly, we observed severe degeneration of bipolar and ganglion cells. In contrast, outer retinal neurons (mainly photoreceptor cells) are mildly affected by colitis. Moreover, retinal inflammatory responses were significantly upregulated during colitis, including microglia activation, lymphocyte infiltration and cytokine/chemokine production. Notably, mucosal addressin cell adhesion molecule 1 (MAdCAM-1) was upregulated in retinal microvessels, especially the superficial and deep plexuses, and recruited gut-homing CD4+ T cells to be co-localized with bipolar and ganglion cells during colitis. Expectedly, in vivo depletion of CD4+ T cells or blockade of MAdCAM-1 greatly alleviated colitis-induced retinal inflammatory responses and neuron degeneration. Therefore, our data provide novel insight into the pathogenesis of IBD-associated retinal dysfunction, and targeted immune therapy directly against MAdCAM-1 might provide a novel approach in the management of eye EIM of IBD.

Microbiota-derived short chain fatty acid promotion of Amphiregulin expression by dendritic cells is regulated by GPR43 and Blimp-1.

Dendritic cells (DC) are the most important antigen-presenting cells, which guide T cell activation and function, and dysregulated DC function might be one of the crucial causes of inflammatory bowel disease (IBD). It has been well-known that microbiota and their metabolites play an essential role in regulating the biology and function of DC, thus contributing to the pathogenesis of IBD. However, the underlying mechanisms remain largely unknown. Amphiregulin (AREG), a molecule of the epidermal growth factor (EGF) family, is primarily described as an epithelial cell-derived cytokine and recognized as a critical regulator of cell proliferation and tissue repair. Here, we found that DC expression of AREG depended on butyrate (a microbiota-derived short chained fatty acid), which required the interaction between butyrate and G-protein-coupled receptor 43 (GPR43). Furthermore, we found that butyrate-GPR43 interaction failed to induce AREG expression in DC deficient in B lymphocyte induced maturation protein 1 (Blimp-1). Notably, DC-derived AREG was indispensable for the protection against experimental colitis in mice. Additionally, AREG expression was significantly decreased in DC from IBD patients. Our data provide novel evidences to interpret how AREG expression is regulated in DC, and shed new light on the mechanisms whereby microbiota regulate DC function.

Sauchinone attenuates inflammatory responses in dendritic cells via Blimp-1 and ameliorates dextran sulfate sodium (DSS)-induced colitis.

Inflammatory bowel disease (IBD) is a complex inflammatory disorder of the digestive tract with dysregulated innate and adaptive immune responses. Dendritic cells (DC), the most important antigen presenting cells, act as bridges connecting the adaptive and innate immune systems, and play a crucial role in the regulation of local homeostasis in the gut and are also essential mediators in the initiation and development of intestinal inflammation. Our recent study found that sauchinone (SAU) was able to ameliorate experimental colitis in mice by restraining Th17 cell differentiation and their pathogenicity. Here, we found that SAU significantly inhibited LPS-induced DC activation. Moreover, SAU suppressed the ability of LPS-primed DC to induce Th1/Th17 cell differentiation, but SAU-treated DC up-regulated their ability to initiate Foxp3+ Treg cell generation. Of note, we found that genetical ablation of Blimp-1 in DC markedly abrogated the SAU suppression of pro-inflammatory cytokine or promote immunomodulatory molecule production by DC. Blimp-1 deficiency boosted the ability of DC to polarize naïve CD4+ T cells into Th1/Th17 cell lineages. SAU failed to alleviated DSS-induced colitis in mice with Blimp-1-deficient DC. Our results shed new lights on the mechanisms of how SAU regulates DC biology and intestinal inflammation.

miR-340 affects sauchinone inhibition of Th17 cell differentiation and promotes intestinal inflammation in inflammatory bowel disease.

The pathogenesis of inflammation bowel disease (IBD) involves exaggerated effector T cell responses and impaired regulatory T cell functions. We previously found that sauchinone (SAU) ameliorated experimental colitis via facilitating Th17 cell production of IL-10, but how SAU regulated Th17 cell differentiation remains unknown. MicroRNAs (miR) have been recognized as a crucial regulator of T cell biology and play a considerable role in IBD. Here, we demonstrated that SAU significantly suppressed miR-340 expression in Th17 cells, and enforced miR-340 expression abrogated SAU inhibition of Th17 differentiation. miR-340 itself was found to facilitate Th17 differentiation, especially the pathogenic "Th1-like" subset. In human IBD, miR-340 was intimately correlated with the disease severity. SAU markedly decreased miR-340 in the inflamed mucosa tissues from IBD patients. Scaffold/matrix-associated region-binding protein 1 (SMAR1) was identified as a target gene of miR-340. We revealed that blockade of miR-340 significantly reduced mucosal damage and Th17 responses in the lamina propria in a mouse colitis model. Our findings suggest that miR-340 negatively affects SAU inhibition of Th17 differentiation and might play a crucial role in the regulation of pathogenic "Th1-like" Th17 cell generation, which might serve as a novel therapeutic target of IBD.