Genetic Coding Variant in GPR65 Alters Lysosomal pH and Links Lysosomal Dysfunction with Colitis Risk.

Although numerous polymorphisms have been associated with inflammatory bowel disease (IBD), identifying the function of these genetic factors has proved challenging. Here we identified a role for nine genes in IBD susceptibility loci in antibacterial autophagy and characterized a role for one of these genes, GPR65, in maintaining lysosome function. Mice lacking Gpr65, a proton-sensing G protein-coupled receptor, showed increased susceptibly to bacteria-induced colitis. Epithelial cells and macrophages lacking GPR65 exhibited impaired clearance of intracellular bacteria and accumulation of aberrant lysosomes. Similarly, IBD patient cells and epithelial cells expressing an IBD-associated missense variant, GPR65 I231L, displayed aberrant lysosomal pH resulting in lysosomal dysfunction, impaired bacterial restriction, and altered lipid droplet formation. The GPR65 I231L polymorphism was sufficient to confer decreased GPR65 signaling. Collectively, these data establish a role for GPR65 in IBD susceptibility and identify lysosomal dysfunction as a potentially causative element in IBD pathogenesis with effects on cellular homeostasis and defense.

Targeted delivery of an anti-inflammatory corticosteroid to Ly6C/G-positive cells abates severity of influenza A symptoms.

The distribution of Ly6C/G-positive cells in response to an infection of the mouse respiratory tract with influenza A virus was followed noninvasively over time by immuno-positron emission tomography. We converted nanobodies that recognize Ly6C and Ly6G, markers of neutrophils and other myeloid cells, as well as an influenza hemagglutinin-specific nanobody, into 89Zr-labeled PEGylated positron emission tomography (PET) imaging agents. The PET images showed strong accumulation of these imaging agents in the lungs of infected mice. Immunohistochemistry of influenza virus-infected mice and control mice, injected with a biotinylated and PEGylated version of the Ly6C/G-specific nanobody, showed the presence of abundant Ly6C/G-positive myeloid cells and positivity for Ly6C/G on bronchial epithelium in influenza virus-infected mice. This is consistent with focal inflammation in the lungs, a finding that correlated well with the immuno-PET results. No such signals were detected in control mice. Having shown by PET the accumulation of the Ly6C/G-specific nanobody in infected lungs, we synthesized conjugates of Ly6C/G-specific nanobodies with dexamethasone to enable targeted delivery of this immunosuppressive corticosteroid to sites of inflammation. Such conjugates reduced the weight loss that accompanies infection, while the equivalent amount of free dexamethasone was without effect. Nanobody-drug conjugates thus enable delivery of drugs to particular cell types at the appropriate anatomic site(s). By avoiding systemic exposure to free dexamethasone, this strategy minimizes its undesirable side effects because of the much lower effective dose of the nanobody-dexamethasone conjugate. The ability to selectively target inflammatory cells may find application in the treatment of other infections or other immune-mediated diseases.

HBV transcription and translation persist despite viral suppression in HBV-HIV co-infected patients on antiretroviral therapy.

BACKGROUND AND AIMS: Liver injury may persist in patients with HBV receiving antiviral therapy who have ongoing transcription and translation. We sought to assess ongoing HBV transcription by serum HBV RNA, translation by serum hepatitis B core related antigen (HBcrAg), and their associations with hepatic HBsAg and HBcAg staining in patients coinfected with HBV and HIV. METHODS: This is a cross-sectional study of 110 adults coinfected with HBV and HIV who underwent clinical assessment and liver biopsy. Immunohistochemistry (IHC) was performed for HBsAg and HBcAg. Viral biomarkers included quantitative HBsAg, HBV RNA, and HBcrAg. RESULTS: Participants' median age was 49 years (male, 93%; Black, 51%; HBeAg+, 65%), with suppressed HBV DNA (79%) and undetectable HIV RNA (77%) on dually active antiretroviral therapy. Overall, HBV RNA and HBcrAg were quantifiable in 81% and 83%, respectively (96% and 100% in HBeAg+, respectively). HBcAg staining was detected in 60% and HBsAg in 79%. Higher HBV RNA was associated with higher HBcAg and HBsAg IHC grades (both p < 0.0001). The HBsAg membranous staining pattern was significantly associated with higher HBV-RNA and HBcrAg levels. CONCLUSION: HBcAg and HBsAg IHC staining persisted despite viral suppression, and IHC grades and staining patterns correlated with markers of transcription (HBV RNA) and translation (HBcrAg). These data indicate that apparent HBV suppression is associated with residual transcription and translation that could contribute to liver pathology. Additional antiviral strategies directed to HBV protein expression may be useful to ameliorate liver injury.

A Prospective Cohort Study of Novel Markers of Hepatitis B Virus Replication in Human Immunodeficiency Virus Coinfection.

BACKGROUND & AIMS: The contribution of the novel biomarkers, hepatitis B virus (HBV) RNA and HBV core-related antigen (HBcrAg), to characterization of HBV-human immunodeficiency virus (HIV) coinfection is unclear. We evaluated the longitudinal dynamics of HBV RNA and HBcrAg and their association with classical HBV serum biomarkers and liver histology and viral staining. METHODS: HBV-HIV co-infected adults from 8 North American centers entered a National Institutes of Health-funded prospective cohort study. Demographic, clinical, serological, and virological data were collected at entry and every 24 to 48 weeks for up to 192 weeks. Participants with HBV RNA and HBcrAg measured ≥2 times (N = 95) were evaluated; 56 had paired liver biopsies obtained at study entry and end of follow-up. RESULTS: Participants had a median age of 50 years; 97% were on combination anti-viral therapy. In hepatitis B e antigen (HBeAg)+ participants, there were significant declines in HBV RNA and HBcrAg over 192 weeks that tracked with declines in HBeAg, hepatitis B surface antigen, HBV DNA, and hepatitis B core antigen (HBcAg) hepatocyte staining grade (all P < .05). In HBeAg- participants, there were not significant declines in HBV RNA (P = .49) and HBcrAg (P = .63), despite modest reductions in hepatitis B surface antigen (P < .01) and HBV DNA (P = .03). HBV serum biomarkers were not significantly related to change in hepatic activity index, Ishak fibrosis score, or hepatocyte HBcAg loss (all P > .05). CONCLUSIONS: In HBV-HIV coinfected adults on suppressive dually active antiviral therapy, the use of novel HBV markers reveals continued improvement in suppression of HBV transcription and translation over time. The lack of further improvement in HBV serum biomarkers among HBeAg- patients suggests limits to the benefit of combination anti-viral therapy and provide rationale for additional agents with distinct mechanisms of action.

Interleukin-10 receptor signaling in innate immune cells regulates mucosal immune tolerance and anti-inflammatory macrophage function.

Intact interleukin-10 receptor (IL-10R) signaling on effector and T regulatory (Treg) cells are each independently required to maintain immune tolerance. Here we show that IL-10 sensing by innate immune cells, independent of its effects on T cells, was critical for regulating mucosal homeostasis. Following wild-type (WT) CD4(+) T cell transfer, Rag2(-/-)Il10rb(-/-) mice developed severe colitis in association with profound defects in generation and function of Treg cells. Moreover, loss of IL-10R signaling impaired the generation and function of anti-inflammatory intestinal and bone-marrow-derived macrophages and their ability to secrete IL-10. Importantly, transfer of WT but not Il10rb(-/-) anti-inflammatory macrophages ameliorated colitis induction by WT CD4(+) T cells in Rag2(-/-)Il10rb(-/-) mice. Similar alterations in the generation and function of anti-inflammatory macrophages were observed in IL-10R-deficient patients with very early onset inflammatory bowel disease. Collectively, our studies define innate immune IL-10R signaling as a key factor regulating mucosal immune homeostasis in mice and humans.

Immunostaining for hepatitis B viral antigens in liver: Association with clinical, biochemical, and virologic features of disease.

BACKGROUND AND AIM: Staining for hepatitis B viral antigens is often done in liver biopsies from patients with chronic hepatitis B, but its correlates with clinical phenotypes are not well described. METHODS: Biopsies were collected from a large cohort of adults and children with chronic hepatitis B viral infection through the Hepatitis B Research Network. Immunohistochemical staining of sections was done for hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) and then centrally read by the pathology committee. The degree of liver injury and pattern of staining were then correlated with clinical characteristics, including the clinical phenotype of hepatitis B. RESULTS: Biopsies from 467 subjects were studied, including 46 from children. Immunostaining for HBsAg was positive in 417 (90%) with scattered hepatocyte staining being the most common pattern. HBsAg staining correlated best with serum levels of HBsAg and hepatitis B viral DNA; the absence of HBsAg staining was often a prelude to loss of HBsAg from serum. HBcAg staining was positive in 225 (49%), and, while cytoplasmic staining was more frequent than nuclear staining, both nuclear and cytoplasmic positivity were often seen in the same specimen. Staining for HBcAg correlated with both level of viremia and liver injury. No biopsies from inactive carriers had stainable HBcAg, while 91% of the biopsies from those with hepatitis B e antigen-positive chronic hepatitis B stained positively for HBcAg. CONCLUSION: Immunostaining for hepatitis B viral antigens may yield helpful insights into liver disease pathogenesis but appears to add little to commonly used serological and biochemical blood tests.

Evolution of Fatty Liver Disease and Relationship With Lipoproteins and Clinical Outcomes in Hepatitis B/Human Immunodeficiency Virus Coinfection.

BACKGROUND: Fatty liver disease (FLD) and hepatitis B virus (HBV) infection occur commonly in human immunodeficiency virus (HIV). FLD resolution is associated with improvement in lipoproteins in HIV-uninfected patients. We evaluated changes in FLD in an HBV/HIV-coinfected cohort. METHODS: One hundred eight HBV/HIV-coinfected adults with baseline liver biopsies were followed every 24 weeks (median, 166 weeks) and 60 had follow-up biopsies. Baseline FLD categories (none, ≥5% steatosis, steatohepatitis), their change, and relationships with clinical and lipid/lipoprotein parameters were explored using multivariable modeling. RESULTS: Median age was 50 years, and 93% were male. At baseline 30% had FLD. With control for lipid-lowering medications and body mass index, low-density lipoprotein (LDL) cholesterol (LDL-C), LDL particle concentration (LDL-P), and apolipoprotein B (apoB) decreased and adiponectin increased over time (all P < .05); On follow-up (vs baseline), there was no significant difference in FLD category (P = .85); 60% remained without FLD, 17% had unchanged, 12% worsening, and 12% improved FLD. Baseline low-density lipoproteins (LDL-C, LDL-P, small LDL-P) and apoB appeared highest in those with unchanged FLD status (all P < .05). No associations between changes in FLD across follow-up (worsening/improvement vs unchanged) and lipid/lipoproteins changes were identified. CONCLUSIONS: In this cohort, there was no significant change in FLD prevalence over a relatively short timeframe. Baseline atherogenic lipids appeared highest in those with persistent steatosis or steatohepatitis, suggesting potentially increased cardiovascular risk in this group, but an independent relationship between individual-level change in FLD status and lipid/lipoprotein levels across follow-up was not observed.

A Prospective Study Evaluating Changes in Histology, Clinical and Virologic Outcomes in HBV-HIV Co-infected Adults in North America.

BACKGROUND AND AIMS: Histological and clinical outcomes in HBV-HIV coinfection in the era of combination antiretroviral therapy (cART) are poorly defined. APPROACH AND RESULTS: Adult patients co-infected with HBV-HIV from eight North American sites were enrolled in this National Institutes of Health (NIH)-funded prospective observational study (n = 139). Demographic, clinical, serological, and virological data were collected at entry and every 24 weeks for ≤ 192 weeks. Paired liver biopsies were obtained at study entry and at ≥ 3 years of follow-up. Biopsies were assessed by a central pathology committee using the modified Ishak scoring system. Clinical outcome rate and changes in histology are reported. Among participants with follow-up data (n = 114), median age was 49 years, 91% were male, 51% were non-Hispanic Black, and 13% had at-risk alcohol use, with a median infection of 20 years. At entry, 95% were on anti-HBV cART. Median CD4 count was 562 cells/mm3 and 93% had HIV < 400 copies/mL. HBeAg was positive in 61%, and HBV DNA was below the limit of quantification (< 20 IU/mL) in 61% and < 1,000 IU/mL in 80%. Clinical events were uncommon across follow-up: one hepatic decompensation, two HCC, no liver transplants, and one HBV-related deaths, with a composite endpoint rate of 0.61/100 person-years. Incident cirrhosis (n = 1), alanine aminotransferase flare (n = 2), and HBeAg loss (n = 13) rates were 0.40, 0.65, and 6.86 per 100 person-years, respectively. No participants had HBsAg loss. Paired biopsy (n = 62; median 3.6 years apart) revealed minimal improvement in Histologic Activity Index (median [interquartile range]: 3 [2-4] to 3 [1-3]; P = 0.02) and no significant change in fibrosis score (1 [1-2] to 1 [0-3]; P = 0.58). CONCLUSIONS: In a North American cohort of adults with HBV-HIV on cART with virological suppression, clinical outcomes and worsening histological disease were uncommon.

Circulatory antigen processing by mucosal dendritic cells controls CD8(+) T cell activation.

Circulatory antigens transit through the small intestine via the fenestrated capillaries in the lamina propria prior to entering into the draining lymphatics. But whether or how this process controls mucosal immune responses remains unknown. Here we demonstrate that dendritic cells (DCs) of the lamina propria can sample and process both circulatory and luminal antigens. Surprisingly, antigen cross-presentation by resident CX3CR1(+) DCs induced differentiation of precursor cells into CD8(+) T cells that expressed interleukin-10 (IL-10), IL-13, and IL-9 and could migrate into adjacent compartments. We conclude that lamina propria CX3CR1(+) DCs facilitate the surveillance of circulatory antigens and act as a conduit for the processing of self- and intestinally absorbed antigens, leading to the induction of CD8(+) T cells, that partake in the control of T cell activation during mucosal immune responses.

Decreased Tissue Omega-6/Omega-3 Fatty Acid Ratio Prevents Chemotherapy-Induced Gastrointestinal Toxicity Associated with Alterations of Gut Microbiome.

Gastrointestinal toxicity (GIT) is a debilitating side effect of Irinotecan (CPT-11) and limits its clinical utility. Gut dysbiosis has been shown to mediate this side effect of CPT-11 by increasing gut bacterial ß-glucuronidase (GUSB) activity and impairing the intestinal mucosal barrier (IMB). We have recently shown the opposing effects of omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) on the gut microbiome. We hypothesized that elevated levels of tissue n-3 PUFA with a decreased n-6/n-3 PUFA ratio would reduce CPT-11-induced GIT and associated changes in the gut microbiome. Using a unique transgenic mouse (FAT-1) model combined with dietary supplementation experiments, we demonstrate that an elevated tissue n-3 PUFA status with a decreased n-6/n-3 PUFA ratio significantly reduces CPT-11-induced weight loss, bloody diarrhea, gut pathological changes, and mortality. Gut microbiome analysis by 16S rRNA gene sequencing and QIIME2 revealed that improvements in GIT were associated with the reduction in the CPT-11-induced increase in both GUSB-producing bacteria (e.g., Enterobacteriaceae) and GUSB enzyme activity, decrease in IMB-maintaining bacteria (e.g., Bifidobacterium), IMB dysfunction and systemic endotoxemia. These results uncover a host-microbiome interaction approach to the management of drug-induced gut toxicity. The prevention of CPT-11-induced gut microbiome changes by decreasing the tissue n-6/n-3 PUFA ratio could be a novel strategy to prevent chemotherapy-induced GIT.

Hepatic Steatosis and Steatohepatitis in a Large North American Cohort of Adults With Chronic Hepatitis B.

INTRODUCTION: Fatty liver disease (FLD) influences liver disease progression and liver cancer risk. We investigated the impact of FLD on liver disease severity in a large North American cohort with chronic hepatitis B virus (HBV). METHODS: Liver biopsies from 420 hepatitis B surface antigen-positive adults enrolled in the Hepatitis B Research Network and who were not on HBV therapy in the previous month were evaluated for inflammation and fibrosis. Steatohepatitis was based on steatosis, hepatocyte ballooning ± Mallory-Denk bodies, and perisinusoidal fibrosis. Models evaluated factors associated with steatohepatitis, and the associations of steatohepatitis with fibrosis, and longitudinal alanine aminotransferase, aspartate aminotransferase, and Fibrosis-4. RESULTS: The median age was 42 years, 62.5% were male, and 79.5% were Asian. One hundred thirty-two (31.4%) patients had FLD (77 [18.3%] steatosis only, 55 [13.1%] steatohepatitis). Older age, overweight/obesity, and diabetes were associated with steatohepatitis. Steatohepatitis (vs no FLD) was associated with 1.68 times higher risk of advanced fibrosis at baseline (95% confidence interval, 1.12-2.51), and there was an indication of higher incident cirrhosis rate during follow-up. Steatohepatitis vs no FLD was also independently associated with, on average, 1.39 times higher alanine aminotransferase (P < 0.01) and 1.25 times higher Fibrosis-4 (P = 0.04) across 4 years. DISCUSSION: Coexisting steatosis occurred in nearly a third of adults (13% had steatohepatitis) with chronic HBV in this North American cohort who underwent liver biopsies. Steatohepatitis was associated with advanced fibrosis and higher biochemical measures of hepatic inflammation over time. Therefore, in addition to viral suppression, screening for and managing metabolic abnormalities is important to prevent disease progression in HBV.

Diagnostic Performance of Shear Wave Elastography in Patients With Autoimmune Liver Disease.

OBJECTIVES: To assess performance of shear wave elastography for evaluation of fibrosis and the histologic stage in patients with autoimmune liver disease (ALD) and to validate previously established advanced fibrosis cutoff values in this cohort. METHODS: Shear wave elastography was performed on patients with ALD with an Aixplorer ultrasound system (SuperSonic Imagine, Aix-en-Provence, France) using an SC6-1 transducer. The median estimated tissue Young modulus was calculated from sets of 8 to 10 elastograms. A blinded, subspecialty-trained pathologist reviewed biopsy specimens. The METAVIR classification was used to stage liver fibrosis and necroinflammation. Steatosis was graded from 0 to 4+. The Kendall τ-b correlation test was performed to identify the correlation between the estimated tissue Young modulus and fibrosis, steatosis, and the necroinflammatory score. The Spearman correlation test was performed to identify the correlation between the estimated tissue Young modulus and clinical data. The diagnostic performance of shear wave elastography for differentiating METAVIR stage F2 or higher from F0 and F1 fibrosis was evaluated by a receiver operating characteristic (ROC) curve analysis. RESULTS: Fifty-one patients with ALD were analyzed. The estimated tissue Young modulus was positively correlated with the fibrosis stage and necroinflammation score (r = 0.386; P < .001; r = 0.338; P = .002, respectively) but not steatosis (r = -0.091; P = .527). Serum aspartate aminotransferase, alanine aminotransferase, and total bilirubin values were positively correlated with the estimated tissue Young modulus (r = 0.501; P < .001; r = 0.44; P = .001; r = 0.291; P = .038). The serum albumin value was negatively correlated (r = -0.309; P = .033). The area under the ROC curve was 0.781 (95% confidence interval, 0.641-0.921) for distinguishing F2 or greater fibrosis from F0 and F1 fibrosis. Based on the ROC curve, an optimal cutoff value of 9.15 kPa was identified (sensitivity, 83.3%; specificity, 72.7%). CONCLUSIONS: Shear wave elastography is a novel noninvasive adjunct to liver biopsy in evaluation and staging of patients with ALD, showing the potential for serial evaluations of disease progression and treatment responses.

mTORC1 in the Paneth cell niche couples intestinal stem-cell function to calorie intake.

How adult tissue stem and niche cells respond to the nutritional state of an organism is not well understood. Here we find that Paneth cells, a key constituent of the mammalian intestinal stem-cell (ISC) niche, augment stem-cell function in response to calorie restriction. Calorie restriction acts by reducing mechanistic target of rapamycin complex 1 (mTORC1) signalling in Paneth cells, and the ISC-enhancing effects of calorie restriction can be mimicked by rapamycin. Calorie intake regulates mTORC1 in Paneth cells, but not ISCs, and forced activation of mTORC1 in Paneth cells during calorie restriction abolishes the ISC-augmenting effects of the niche. Finally, increased expression of bone stromal antigen 1 (Bst1) in Paneth cells­an ectoenzyme that produces the paracrine factor cyclic ADP ribose­mediates the effects of calorie restriction and rapamycin on ISC function. Our findings establish that mTORC1 non-cell-autonomously regulates stem-cell self-renewal, and highlight a significant role of the mammalian intestinal niche in coupling stem-cell function to organismal physiology.

Interleukin 1ß Mediates Intestinal Inflammation in Mice and Patients With Interleukin 10 Receptor Deficiency.

Interleukin 10 receptor (IL10R)-deficient mice develop spontaneous colitis and, similarly, patients with loss-of-function mutations in IL10R develop severe infant-onset inflammatory bowel disease. Loss of IL10R signaling in mouse and human macrophages is associated with increased production of interleukin 1ß. We demonstrated that innate immune production of IL1ß mediates colitis in IL10R-deficient mice. Transfer of Il1r1-/- CD4+ T cells into Rag1-/-/Il10rb-/- mice reduced the severity of their colitis (compared to mice that received CD4+ T cells that express IL1R), accompanied by decreased production of interferon gamma, tumor necrosis factor-α, and IL17A. In macrophages from mice without disruption of IL10R signaling or from healthy humans (controls), incubation with IL10 reduced canonical activation of the inflammasome and production of IL1ß through transcriptional and post-translational regulation of NLRP3. Lipopolysaccharide and adenosine triphosphate stimulation of macrophages from Il10rb-/- mice or IL10R-deficient patients resulted in increased production of IL1ß. Moreover, in human IL10R-deficient macrophages, lipopolysaccharide stimulation alone triggered IL1ß secretion via non-canonical, caspase 8-dependent activation of the inflammasome. We treated 2 IL10R-deficient patients with severe and treatment-refractory infant-onset inflammatory bowel disease with the IL1-receptor antagonist anakinra. Both patients had marked clinical, endoscopic, and histologic responses after 4-7 weeks. This treatment served as successful bridge to allogeneic hematopoietic stem cell transplantation in 1 patient. Our findings indicate that loss of IL10 signaling leads to intestinal inflammation, at least in part, through increased production of IL1 by innate immune cells, leading to activation of CD4+ T cells. Agents that block IL1 signaling might be used to treat patients with inflammatory bowel disease resulting from IL10R deficiency.

Selective Targeting of a Disease-Related Conformational Isoform of Macrophage Migration Inhibitory Factor Ameliorates Inflammatory Conditions.

Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine and counterregulator of glucocorticoids, is a potential therapeutic target. MIF is markedly different from other cytokines because it is constitutively expressed, stored in the cytoplasm, and present in the circulation of healthy subjects. Thus, the concept of targeting MIF for therapeutic intervention is challenging because of the need to neutralize a ubiquitous protein. In this article, we report that MIF occurs in two redox-dependent conformational isoforms. We show that one of the two isoforms of MIF, that is, oxidized MIF (oxMIF), is specifically recognized by three mAbs directed against MIF. Surprisingly, oxMIF is selectively expressed in the plasma and on the cell surface of immune cells of patients with different inflammatory diseases. In patients with acute infections or chronic inflammation, oxMIF expression correlated with inflammatory flare-ups. In addition, anti-oxMIF mAbs alleviated disease severity in mouse models of acute and chronic enterocolitis and improved, in synergy with glucocorticoids, renal function in a rat model of crescentic glomerulonephritis. We conclude that oxMIF represents the disease-related isoform of MIF; oxMIF is therefore a new diagnostic marker for inflammation and a relevant target for anti-inflammatory therapy.

Intestinal Alkaline Phosphatase Attenuates Alcohol-Induced Hepatosteatosis in Mice.

BACKGROUND AND AIMS: Bacterially derived factors from the gut play a major role in the activation of inflammatory pathways in the liver and in the pathogenesis of alcoholic liver disease. The intestinal brush-border enzyme intestinal alkaline phosphatase (IAP) detoxifies a variety of bacterial pro-inflammatory factors and also functions to preserve gut barrier function. The aim of this study was to investigate whether oral IAP supplementation could protect against alcohol-induced liver disease. METHODS: Mice underwent acute binge or chronic ethanol exposure to induce alcoholic liver injury and steatosis ± IAP supplementation. Liver tissue was assessed for biochemical, inflammatory, and histopathological changes. An ex vivo co-culture system was used to examine the effects of alcohol and IAP treatment in regard to the activation of hepatic stellate cells and their role in the development of alcoholic liver disease. RESULTS: Pretreatment with IAP resulted in significantly lower serum alanine aminotransferase compared to the ethanol alone group in the acute binge model. IAP treatment attenuated the development of alcohol-induced fatty liver, lowered hepatic pro-inflammatory cytokine and serum LPS levels, and prevented alcohol-induced gut barrier dysfunction. Finally, IAP ameliorated the activation of hepatic stellate cells and prevented their lipogenic effect on hepatocytes. CONCLUSIONS: IAP treatment protected mice from alcohol-induced hepatotoxicity and steatosis. Oral IAP supplementation could represent a novel therapy to prevent alcoholic-related liver disease in humans.

Atg16L1 T300A variant decreases selective autophagy resulting in altered cytokine signaling and decreased antibacterial defense.

A coding polymorphism (Thr300Ala) in the essential autophagy gene, autophagy related 16-like 1 (ATG16L1), confers increased risk for the development of Crohn disease, although the mechanisms by which single disease-associated polymorphisms contribute to pathogenesis have been difficult to dissect given that environmental factors likely influence disease initiation in these patients. Here we introduce a knock-in mouse model expressing the Atg16L1 T300A variant. Consistent with the human polymorphism, T300A knock-in mice do not develop spontaneous intestinal inflammation, but exhibit morphological defects in Paneth and goblet cells. Selective autophagy is reduced in multiple cell types from T300A knock-in mice compared with WT mice. The T300A polymorphism significantly increases caspase 3- and caspase 7-mediated cleavage of Atg16L1, resulting in lower levels of full-length Atg16Ll T300A protein. Moreover, Atg16L1 T300A is associated with decreased antibacterial autophagy and increased IL-1ß production in primary cells and in vivo. Quantitative proteomics for protein interactors of ATG16L1 identified previously unknown nonoverlapping sets of proteins involved in ATG16L1-dependent antibacterial autophagy or IL-1ß production. These findings demonstrate how the T300A polymorphism leads to cell type- and pathway-specific disruptions of selective autophagy and suggest a mechanism by which this polymorphism contributes to disease.

SLAMF4 Is a Negative Regulator of Expansion of Cytotoxic Intraepithelial CD8+ T Cells That Maintains Homeostasis in the Small Intestine.

BACKGROUND & AIMS: Intraepithelial T lymphocyte cells (IEL) are the first immune cells to respond to pathogens; they help maintain the integrity of the epithelial barrier. We studied the function of the mouse glycoprotein Signaling Lymphocyte Activation Molecule Family receptor (SLAMF) 4 (encoded by Slamf4) on the surface of CD8αß αß T-cell receptor (TCR)(+) IELs, and the roles of these cells in homeostasis of the small intestine in mice. METHODS: SLAMF4(-) CD8(+) αßTCR(+) cells isolated from spleens of OT-I Rag1(-/-) mice were induced to express gut-homing receptors and transferred to C57BL/6J mice; levels of SLAMF4(+) cells were measured in small intestine tissues. After administration of anti-CD3 or antigen, with or without anti-SLAM4, to C57BL/6J and Slamf4(-/-) mice, CD8αß αßTCR(+) IELs were collected; cytokine production and cytotoxicity were measured. Depletion of CX3CR1(+) phagocytes was assessed in mice by live-cell confocal imaging or by cytofluorometry; small intestine tissues were analyzed by histology and inflammation was quantified. RESULTS: Splenic CD8(+) αßTCR(+) cells began to express SLAMF4 only after migrating to the small intestine. Injection of C57BL/6J mice with anti-SLAMF4 and anti-CD3 increased levels of interleukin 10 and interferon gamma secretion by IEL, compared with injection of anti-CD3 only. Similarly, the number of granzyme B(+) cytotoxic CD8(+) αßTCR(+) IELs increased in Slamf4(-/-) mice after injection of anti-CD3 and anti-SLAMF4, administration of antigen, or injection of anti-CD3. Surprisingly, in vivo activation of CD8αß(+) IELs with anti-CD3 or antigen caused transient depletion of CX3CR1(+) phagocytes, which was prolonged by co-injection with anti-SLAMF4 or in Slamf4(-/-) mice. Anti-CD3 aggravated inflammation in the small intestines of Slamf4(-/-) mice and Eat2a(-/-)Eat2b(-/-) mice, indicated by flattened villi and crypt hyperplasia. CONCLUSIONS: In mice, the intestinal environment induces SLAMF4 expression and localization to the surface of CD8(+) αßTCR(+) IELs. Signaling via SLAMF4 controls expansion of cytotoxic CD8αß(+) IELs, which regulate the reversible depletion of lamina propria phagocytes and inflammation in the small intestine.

The cell surface receptor Slamf6 modulates innate immune responses during Citrobacter rodentium-induced colitis.

The homophilic cell surface receptors CD150 (Slamf1) and CD352 (Slamf6) are known to modulate adaptive immune responses. Although the Th17 response was enhanced in Slamf6(-/-) C57BL/6 mice upon oral infection with Citrobacter rodentium, the pathologic consequences are indistinguishable from an infection of wild-type C57BL/6 mice. Using a reporter-based binding assay, we show that Slamf6 can engage structures on the outer cell membrane of several Gram(-) bacteria. Therefore, we examined whether Slamf6, like Slamf1, is also involved in innate responses to bacteria and regulates peripheral inflammation by assessing the outcome of C. rodentium infections in Rag(-/-) mice. Surprisingly, the pathology and immune responses in the lamina propria of C. rodentium-infected Slamf6(-/-) Rag(-/-) mice were markedly reduced as compared with those of Rag(-/-) mice. Infiltration of inflammatory phagocytes into the lamina propria was consistently lower in Slamf6(-/-) Rag(-/-) mice than in Rag(-/-) animals. Concomitant with the reduced systemic translocation of the bacteria was an enhanced production of IL-22, suggesting that Slamf6 suppresses a mucosal protective program. Furthermore, administering a mAb (330) that inhibits bacterial interactions with Slamf6 to Rag(-/-) mice ameliorated the infection compared with a control antibody. We conclude that Slamf6-mediated interactions of colonic innate immune cells with specific Gram(-) bacteria reduce mucosal protection and enhance inflammation, contributing to lethal colitis that is caused by C. rodentium infections in Rag(-/-) mice.