Dysregulated LIGHT expression on T cells mediates intestinal inflammation and contributes to IgA nephropathy

IgA nephropathy associated with Crohn's disease

The relationship between IgA nephropathy (IgAN) and Crohn’s disease was reported. IgAN is the most common primary glomerulonephritis and one of the leading causes of chronic kidney disease and end-stage renal failure, and up to 50% of cases progressed to end-stage renal disease within 25 years after IgAN diagnosis. However, specific and effective therapeutic strategies are still lacking. In this review, we discuss the possibility of the mechanism involved in IgAN associated with Crohn’s disease based on the findings of basic and clinical studies. Although the etiology of IgAN associated with Crohn’s disease is not permanent and various factors are thought to be involved, the stabilization of the disease condition of Crohn’s disease is believed to help treat IgAN.

Mucosal Immune System Dysregulation in the Pathogenesis of IgA Nephropathy

The mucosal immune system, via a dynamic immune network, serves as the first line of defense against exogenous antigens. Mucosal immune system dysregulation is closely associated with the pathogenesis of immunoglobulin A nephropathy (IgAN), as illustrated by IgAN having the clinical feature of gross hematuria, often concurrent with mucosal infections. Notably, previous studies have demonstrated the efficacy of tonsillectomy and found that a targeted-release formulation of budesonide reduced proteinuria in patients with IgAN. However, it remains unclear how exogenous antigens interact with the mucosal immune system to induce or exacerbate IgAN. Thus, in this review, we focus on the dysregulation of mucosal immune response in the pathogenesis of IgAN.

Causal association between inflammatory bowel disease and IgA nephropathy: A bidirectional two-sample Mendelian randomization study

Background: An association between inflammatory bowel disease (IBD) [which includes ulcerative colitis (UC) and Crohn's disease (CD)] and IgA nephropathy (IgAN) has been discovered in observational studies, but the causal relationship is still unknown. The aim of this study was to clarify the causal link between IBD (which includes UC and CD) and IgAN via a two-sample Mendelian randomization (MR) analysis. Methods: Eligible single-nucleotide polymorphisms (SNPs) were selected as instrumental variables (IVs) for analyses and were obtained from the publicly available genome-wide association study (GWAS) summary statistics. Inverse-variance weighting (IVW), Mendelian randomization-Egger (MR-Egger) regression, the Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) test, and the weighted median were utilized to obtain the results. The MR-PRESSO test and MR-Egger regression were also performed to detect and correct horizontal pleiotropy. The Cochran's Q test and "leave-one-out" analysis were also conducted to assess the stability and reliability of the MR results. Results: This study found that IBD, UC, and CD all had significant positive causal effects on IgAN risk (IBD: OR = 1.58, 95% CI 1.15-2.16, p = 4.53 × 10-3; UC: OR = 1.55, 95% CI 1.14-2.11, p = 4.88 × 10-3; CD: OR = 1.57, 95% CI 1.21-2.03, p = 5.97 × 10-4). No significant horizontal pleiotropic effect was found for the causal association between IBD, UC, CD, and the risk of IgAN. Cochran's Q test identified no evidence of heterogeneity for the IV estimates. The "leave-one-out" sensitivity analysis also revealed that the MR results were robust. Conclusion: The results of this two-sample MR analysis supported that IBD, UC, and CD were causally associated with the risk of IgAN, while there was no sufficient evidence for the causal effect of IgAN on IBD, UC, or CD. Our findings provide theoretical support and a new perspective for the diagnosis and treatment of these two diseases.

Association between genetic variants and the risk of nivolumab-induced immune-related adverse events

Aim: We sought to identify the variants that could predict the risk of nivolumab-induced immune-related adverse events (irAEs) in patients with cancer. Patients & methods: We enrolled 622 Japanese patients and carried out a genome-wide association study. The associations for 507 single nucleotide polymorphisms (SNPs) showing p < 0.001 were further investigated using an independent cohort. Results: In the combined analysis, possible associations were found for a total of 90 SNPs. Although no SNPs were identified to be significantly associated with nivolumab-induced irAEs, the SNP most strongly associated with nivolumab-induced irAEs was rs469490. Conclusion: This study is an important hypothesis-generating study to guide future studies in larger and/or other ethnic cohorts.

Renal manifestations in inflammatory bowel disease: a systematic review

As extra-intestinal manifestations (EIMs) are frequent in inflammatory bowel disease (IBD) and affect morbidity and sometimes even mortality, vigilance in the surveillance of EIMs and installing the appropriate treatment are essential. Data on renal manifestations in patients with IBD are however rare. Nevertheless, up to 5-15% of adult patients with IBD will develop chronic kidney disease over time. The pathophysiology of renal involvement in patients with IBD is complex and poorly understood, with a wide range of renal disorders affecting the glomeruli and/or the tubular structure. Furthermore, medication used to treat IBD can be potentially nephrotoxic and metabolic complication due to the disease itself can furthermore cause renal damage. The aim of this systematic review is to provide an overview of the existing data in literature on these renal manifestations and complications in patients with IBD.

Orange-derived and dexamethasone-encapsulated extracellular vesicles reduced proteinuria and alleviated pathological lesions in IgA nephropathy by targeting intestinal lymphocytes

Current evidence highlights the critical role of the gut-kidney axis in the pathogenesis of IgA nephropathy (IgAN). However, few attempts have been made to explore targeted intestinal immunity therapy. This research aims to develop an oral intestine targeting medication based on extracellular vesicles (EVs) and investigate its therapeutic efficacy in IgAN. EVs were isolated from orange juice and electroporated with dexamethasone sodium phosphate (DexP). After oral administration, EVs-DexP was picked up by lymphocytes in the submucosal area of ileocecum. EVs-DexP outperformed DexP not only in suppressing lymphocyte stimulation in vitro but also in alleviating renal pathological lesions in the IgAN mouse model. Clinical improvement was accompanied by a reducing IgA secreted by the intestine and a decreasing IgA + B220 + lymphocytes in Peyer’s patches. The present study develops a cost-effective, biofriendly EVs-based glucocorticoid strategy for IgAN.

Increased proportion of follicular helper T cells is associated with B cell activation and disease severity in IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis, characterized by glomerular deposition of IgA immune complexes, mainly produced by B cells under the regulation of CD4⁺T cells. However, the alterations of specific CD4⁺T cell subsets and the mechanism of B cells activation in IgAN remain unclear. Therefore, we aimed to investigate the landscape characteristics and role of CD4⁺T cells in the progression of IgAN. We identified that the proportion of Th2, Th17 and Tfh (follicular helper T) cells in patients with IgAN was significantly higher than that of healthy controls (P < 0.05). Single-cell RNA sequencing of peripheral blood mononuclear cells (PBMCs) showed that Th cells and B cells in patients with IgAN were more activated. Correspondingly, multiplex immunohistochemistry staining of renal biopsy showed increased infiltration of CD4⁺T and B cells in the kidneys of patients with IgAN. The degree of infiltration was positively correlated with the degree of renal damage. Interestingly, the proportion of Tfh cells in peripheral blood was positively correlated with the severity of proteinuria. Moreover, the proximity position of Tfh cells and B cells suggested that cell-cell interactions between Tfh and B cells were happening in situ. Intercellular communication analysis also showed enhanced interaction between Tfh cells and B cells in IgAN. Our findings suggested that Tfh cells of patients possibly contributed to the progression of IgAN by activating B cells via cell-cell interactions and TNFSF14-TNFRSF14 may be an underlying signaling pathway.

Title IgA Nephropathy and Oral Bacterial Species Related to Dental Caries and Periodontitis

A relationship between IgA nephropathy (IgAN) and bacterial infection has been suspected. As IgAN is a chronic disease, bacteria that could cause chronic infection in oral areas might be pathogenetic bacteria candidates. Oral bacterial species related to dental caries and periodontitis should be candidates because these bacteria are well known to be pathogenic in chronic dental disease. Recently, several reports have indicated that collagen-binding protein (cnm)-(+) Streptococcs mutans is relate to the incidence of IgAN and the progression of IgAN. Among periodontal bacteria, Treponema denticola, Porphyromonas gingivalis and Campylobacte rectus were found to be related to the incidence of IgAN. These bacteria can cause IgAN-like histological findings in animal models. While the connection between oral bacterial infection, such as infection with S. mutans and periodontal bacteria, and the incidence of IgAN remains unclear, these bacterial infections might cause aberrantly glycosylated IgA1 in nasopharynx-associated lymphoid tissue, which has been reported to cause IgA deposition in mesangial areas in glomeruli, probably through the alteration of microRNAs related to the expression of glycosylation enzymes. The roles of other factors related to the incidence and progression of IgA, such as genes and cigarette smoking, can also be explained from the perspective of the relationship between these factors and oral bacteria. This review summarizes the relationship between IgAN and oral bacteria, such as cnm-(+) S. mutans and periodontal bacteria.

Immunological drivers of IgA nephropathy: Exploring the mucosa-kidney link

IgA nephropathy (IgAN) is the most common pattern of primary glomerular disease reported worldwide. Up to 40% of those with IgAN progress to end-stage kidney disease within 20 years of diagnosis, with no currently available disease-specific treatment. This is likely to change rapidly, with evolving insights into the mechanisms driving this disease. IgAN is an immune-complex-mediated disease, and its pathophysiology has been framed by the 'four-hit hypothesis', which necessitates four events to occur for clinically significant disease to develop. However, this hypothesis does not explain the wide variability observed in its presentation or clinical progression. Recently, there has been great interest in exploring the role of the mucosal immune system in IgAN, especially given the well-established link between mucosal infections and disease flares. Knowledge of antigen-mucosal interactions is now being successfully leveraged for therapeutic purposes; the gut-directed drug Nefecon (targeted release formulation-budesonide) is on track to become the first medication to be approved specifically for the treatment of IgAN. In this review, we examine established immunological paradigms in IgAN, explore how antigen-mucosal immune responses drive disease, and discuss how this knowledge is being used to develop new treatments.

LIGHT of pulmonary NKT cells annihilates tissue protective alveolar macrophages in augmenting severe influenza pneumonia

CD1d-restricted natural killer T (NKT) cells are innate-like T lymphocytes with protective or pathogenic roles in the development of influenza pneumonia. Here, we show that lung-infiltrated and activated NKT cells are the major cellular source of LIGHT/TNFSF14, which determines the severity of pulmonary pneumonia by highly deteriorative influenza A virus (IAV) infection. Compared to wild-type mice, LIGHT^-/- mice exhibit much lower morbidity and mortality to IAV, due to alleviated lung damage and reduced apoptosis of alveolar macrophages (AMs). LIGHT preferentially promotes cell death of lymphotoxin β receptors positive (LTβR⁺) AMs but not herpesvirus entry mediator positive (HVEM⁺) AMs. Therefore, these results suggest that NKT-derived LIGHT augments cell death of the tissue protective AMs in exacerbating lung pathology and susceptibility to fatal influenza infection. Suppression of LIGHT signaling might be a viable option in the treatment of influenza-associated acute respiratory distress syndrome.

History of IgA Nephropathy Mouse Models

IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the world. It was first described in 1968 by Jean Berger and Nicole Hinglais as the presence of intercapillary deposits of IgA. Despite this simple description, patients with IgAN may present very broad clinical features ranging from the isolated presence of IgA in the mesangium without clinical or biological manifestations to rapidly progressive kidney failure. These features are associated with a variety of histological lesions, from the discrete thickening of the mesangial matrix to diffuse cell proliferation. Immunofluorescence on IgAN kidney specimens shows the isolated presence of IgA or its inconsistent association with IgG and complement components. This clinical heterogeneity of IgAN clearly echoes its complex and multifactorial pathophysiology in humans, inviting further analyses of its various aspects through the use of experimental models. Small-animal models of IgAN provide the most pertinent strategies for studying the multifactorial aspects of IgAN pathogenesis and progression. Although only primates have the IgA1 subclass, several murine models have been developed in which various aspects of immune responses are deregulated and which are useful in the understanding of IgAN physiopathology as well as in the assessment of IgAN therapeutic approaches. In this manuscript, we review all murine IgAN models developed since 1968 and discuss their remarkable contribution to understanding the disease.

Are there animal models of IgA nephropathy?

Immunoglobulin A (IgA) nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Up to 40% of IgAN patients develop end-stage kidney disease after 15-20 years. Despite the poor prognosis associated with this multifactorial disease, no clear treatment strategy has been identified, primarily due to the lack of understanding of its pathogenesis. Clinical observations indicate that aberrant IgAN immune systems, rather than intrinsic renal abnormalities, may be involved in its pathogenesis. Moreover, nephritogenic IgA and its related immune complexes are considered to be produced not only in the mucosa, but also in systemic immune sites, such as the bone marrow; however, there are numerous challenges to understanding this dynamic and complex immune axis in humans. Thus, several investigators have used experimental animal models. Although there are inter-strain differences in IgA molecules and immune responses between humans and rodents, animal models remain a powerful tool for investigating IgAN's pathogenesis, and the subsequent development of effective treatments. Here, we introduced some classical models of IgAN with or without genetic manipulation and recent translational approaches with some promising models. This includes humanized mouse models expressing human IgA1 and human IgA Fc receptor (CD89) that develops spontaneously the disease. Pre-clinical studies targeting IgA1 are discussed. Together, animal models are very useful tools to study pathophysiology and to validate new therapeutic approaches for IgAN.

Henoch-Schönlein purpura and crohn's disease: Expanding the range of association in pediatric patients

The association of new onset Henoch-Schönlein purpura (HSP) and inflammatory bowel disease (IBD) has been reported in the setting of concomitant anti-TNF-ɑ treatment. We present two pediatric IBD cases who developed new onset HSP without such association. These cases add to the literature by suggesting an association between HSP and IBD in pediatric population. We discuss possible underlying pathophysiological mechanisms, suggesting some commonality with IgA nephropathy. Increased awareness for HSP in pediatric IBD patients regardless of anti-TNF- ɑ therapy involvement is important for timely recognition and appropriate multi-disciplinary management.

The Phenotypic Difference of IgA Nephropathy and its Race/Gender-dependent Molecular Mechanisms

IgA nephropathy (IgAn), defined by the pre dominant de position of IgA in the glomerular mesangium, is the most common form of GN throughout the world. However, its incidence, sex distribution, clinical presentation, and progression and pathogenic initiating factors are largely variable and do not fit such a simple definition. To assess the heterogeneity of this disease, we recently conducted a clinical survey on the presentation and clinical management of patients with IgAn in Europe and Japan. This clinical survey highlights similarities and differences in patients from different cont inents. The survey revealed obvious differences between nations in the frequency of gastrointestinal complications, including inflammatory bowel diseases (IBD) and celiac disease, which were more frequent in European patients. Such findings are compatible with susceptibility loci related to intestinal immunity and IBD in recent genome wide association studies (GWAS) on IgAn. However, most of the molecules in these mucosal-related loci fulfill the immunologic function not only of gut-associated lymphoid tissue (GALT), but also nasopharyngeal/bronchial-associated lymphoid tissues (NALT/BALT). Indeed, a similar frequency of macrohematuria coinciding with upper respiratory infection, a hallmark manifestation of this disease, was found in the survey, emphasizing the pathogenic roles of these molecules in the NALT/BALT of patients with IgAn. Recent experimental and clinical studies including GWAS on multiple common infections and IBD indicate immune crosstalk between GALT and NALT/BALT, and some related mediators, such as TNF superfamily ligands (APRIL/BAFF). This review explains the epidemiologic heterogeneity of this disease with the clinical survey, and discusses race and sex-dependent molecular mechanisms.

Nasal-associated lymphoid tissue is the major induction site for nephritogenic IgA in murine IgA nephropathy

Dysregulation of mucosal immunity may play a role in the pathogenesis of IgA nephropathy (IgAN). However, it is unclear whether the nasal-associated lymphoid tissue (NALT) or gut-associated lymphatic tissue is the major induction site of nephritogenic IgA synthesis. To examine whether exogenous mucosal antigens exacerbate the pathogenesis of IgAN, we assessed the disease phenotypes of IgAN-onset ddY mice housed germ-free. These mice were transferred to a specific pathogen-free environment and divided into three groups: challenged with the Toll-like receptor 9 (TLR9) ligand CpG-oligodeoxynucleotide, fecal transplantation, and the untreated control group. The levels of aberrantly glycosylated IgA and IgG-IgA immune complexes were measured in the serum and supernatant of cultured cells purified from the NALT, mesenteric lymph nodes, and Peyer's patch. Although the germ-free IgAN-onset ddY mice did not develop IgAN, they showed aggravation of kidney injury with mesangial IgA deposition after transfer to the specific pathogen-free state. The NALT cells produced more aberrantly glycosylated IgA than those from the mesenteric lymph node and Peyer's patch, resulting in induction of IgG-IgA immune complexes formation. Additionally, TLR9 enhanced the production of nephritogenic IgA and IgG-IgA immune complexes by nasal-associated lymphoid but not gut-associated lymphatic cells. Furthermore, the germ-free IgAN-onset ddY mice nasally immunized with CpG-oligonucleotide showed aggravation of kidney injury with mesangial IgA deposition, whereas those that received fecal transplants did not develop IgAN. Thus, NALT is the major induction site of the production of aberrantly glycosylated IgA in murine IgAN.

Different renal manifestations associated with very early onset pediatric inflammatory bowel disease: case report and review of literature

Background

Inflammatory bowel diseases are characterized by chronic inflammation of the gastrointestinal tract. In particular, Crohn disease and ulcerative colitis represent the two most common types of clinical manifestations. Extraintestinal manifestations of inflammatory bowel diseases represent a common complications, probably reflecting the systemic inflammation. Renal involvement is reported in 4–23% of cases. However, available data are limited to few case series and retrospective analysis, therefore the real impact of renal involvement is not well defined.

Case presentation

We report the case of a 10-years old male affected by very early onset unclassified-Inflammatory bowel diseases since he was 1-year old, presenting with a flare of inflammatory bowel diseases associated with acute kidney injury due to granulomatous interstitial nephritis. Of interest, at 7-year-old, he was treated for IgA nephropathy.

To our knowledge, no previous reports have described a relapse of renal manifestation in inflammatory bowel diseases, characterized by two different clinical and histological phenotypes.

Conclusions

The link between the onset of kidney injuries with flares of intestinal inflammation suggest that nephritis maybe considered an extra-intestinal manifestation correlated with active inflammatory bowel disease. However, if granulomatous interstitial nephritis represents a cell-mediated hypersensitivity reaction than a true extraintestinal manifestation of inflammatory bowel diseases is still not clarified. We suggest as these renal manifestations here described may be interpreted as extraintestinal disorder and also considered as systemic signal of under treatment of the intestinal disease.

Renal deposition and clearance of recombinant poly-IgA complexes in a model of IgA nephropathy

IgA nephropathy (IgAN) is the most common type of glomerulonephritis worldwide, which follows a chronic but nonetheless highly variable course of progression. IgA immune complexes are the primary source of renal deposits in IgAN. Apart from the presence of granular IgA1 deposits in the glomerular mesangium and mesangial hypercellularity as common features, the detailed process of IgA1 deposition and clearance in the kidney remains unclear. We sought to examine the dynamics of IgA deposition and tissue plasticity in response to deposits including their intrarenal clearance. We followed a synthetic approach to produce a recombinant fusion between IgA Fc (rIgA) and a biotin tag, which was subsequently induced with streptavidin (SA) to form an oligomeric poly-IgA mimic. Both uninduced rIgA (mono-rIgA) and polymeric SA-rIgA (poly-rIgA) were injected intravenously into Wistar rats. Plasma IgA levels and renal and liver histology were examined in a time series. In contrast to mono-rIgA, this synthetic poly-rIgA analog formed renal deposits exclusively in the glomerulus and were mostly cleared in 3 h. However, repeated daily injections for 12 days caused long-lasting and stronger glomerular IgA deposition together with IgG and complement C3, in association with mesangial cell proliferation, matrix expansion, and variable degrees of albuminuria and hematuria that phenocopied IgAN. Ex vivo, poly-rIgA bound cultured mesangial cells and elicited cytokine production, in addition to activating plasma C3 that was consistent with the actions of IgA immune complexes in IgAN pathogenesis. Remarkably, the kidneys were able to reverse all pathologic manifestations and restore normal glomerular histology 2 weeks after injections were halted. The synthetic model showed the kinetics between the intricate balance of renal deposition and clearance, as well as glomerular plasticity towards healing. Together, the results revealed a priming effect of existing deposits in promoting stronger and longer-lasting IgA deposition to cause renal damage. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Integrated Fecal Microbiome and Serum Metabolomics Analysis Reveals Abnormal Changes in Rats with Immunoglobulin A Nephropathy and the Intervention Effect of Zhen Wu Tang

Immunoglobulin A nephropathy (IgAN), an autoimmune renal disease with complicated pathogenesis, is one of the principal reasons for end-stage renal disease in the clinic. Evidence has linked apparent alterations in the components of the microbiome and metabolome to renal disease in rats. However, thus far, there is insufficient evidence that supports the potential relationship between gut microbiome, circulating metabolites, and IgAN. This study was designed to probe the effects of IgAN on intestinal microecology and metabolic phenotypes and to understand the possible underlying mechanisms. Fecal and serum samples were collected from IgAN rats. Composition of the gut microbiota and biochemical changes in the metabolites was analyzed using 16S rDNA sequencing and untargeted metabolomics. The IgAN rats exhibited renal insufficiency and increased concentration of 24-h urine protein, in addition to deposition of IgA and IgG immune complexes in the kidney tissues. There was a disturbance in the balance of gut microbiota in IgAN rats, which was remarkably associated with renal damage. Marked changes in microbial structure and function were accompanied by apparent alterations in 1,403 serum metabolites, associated with the disorder of energy, carbohydrate, and nucleotide metabolisms. Administration of Zhen Wu Tang ameliorated microbial dysbiosis and attenuated the renal damage. Besides, treatment with Zhen Wu Tang modulated the metabolic phenotype perturbation in case of gut microbiota dysbiosis in IgAN rats. In conclusion, these findings provided a comprehensive understanding of the potential relationship between the intestinal microbiota and metabolic phenotypes in rats with IgAN. Elucidation of the intestinal microbiota composition and metabolic signature alterations could identify predictive biomarkers for disease diagnosis and progression, which might contribute to providing therapeutic strategies for IgAN.

IgA nephropathy in association with inflammatory bowel diseases: results from a national study and systematic literature review

BACKGROUND

Little is known about clinical characteristics and kidney outcome in patients with biopsy-proven immunoglobulin A nephropathy (IgAN) in a context of inflammatory bowel disease (IBD).

METHODS

We conducted a retrospective multicenter study with centralized histological review, to analyze the presentation, therapeutic management and outcome of 24 patients suffering from IBD associated IgAN relative to a cohort of 134 patients with primary IgAN without IBD.

RESULTS

Crohn's disease and ulcerative colitis accounted for 75% and 25% of IBD-associated IgAN cases, respectively. IBD was diagnosed before IgAN in 23 cases (a mean of 9 years previously) and was considered active at IgAN onset in 23.6% of patients. Hypertension was present in 41.7% of patients. Urinary protein-to-creatinine ratio exceeded 100 mg/mmol in 70.8% of patients (mean: 254 mg/mmol). Estimated glomerular filtration rate (eGFR) exceeded 60 ml/min/1.73m2 in 13/24 patients and only one patient required dialysis. In the Oxford MEST-C classification of renal biopsies, 57% were M1, 48% E1, 76% S1, 57% T1+T2 and 38% C1+C2. Steroids were administered in 50% of cases. After a mean follow-up of 7.2 years, four patients (16.7%) had a poor kidney outcome: end-stage renal disease (n = 3) or a > 50% decrease in eGFR from initial values (n = 1). A similar evolution was observed in patients with primitive IgAN.

CONCLUSIONS

This first case series suggests that IBD-associated IgAN have frequent inflammatory lesions at onset and variable long-term outcome.

Expression of LIGHT/TNFSF14 and Its Receptors, HVEM and LTβR, Correlates with the Severity of Fibrosis in Lacrimal Sacs from Patients with Lacrimal Duct Obstruction

Introduction

Fibrosis is one of the factors contributing to the development of primary acquired lacrimal duct obstruction (LDO). LIGHT (homologous to lymphotoxins, exhibiting inducible expression and competing with herpes simplex virus glycoprotein D for herpes virus entry mediator [HVEM]), a receptor expressed by T lymphocytes, has recently emerged as a new regulator of connective tissue remodeling and fibrotic response. The purpose of this study was to evaluate the role of LIGHT in the pathogenesis of LDO through: (1) assessment of expression of LIGHT and its two receptors, HVEM and LTβR (lymphotoxin β receptor), and (2) investigation of potential relationships between expression of LIGHT and its receptors and clinical and histopathologic features.

Methods

Lacrimal sacs of 30 patients undergoing endoscopic dacryocystorhinostomy because of LDO were assessed intraoperatively and histopathologically with respect to inflammation and fibrosis. Expression of LIGHT, HVEM and LTβR was assessed by immunohistochemistry using specific antibodies and evaluated semiquantitatively using a four-grade scoring system.

Results

All investigated molecules, LIGHT/TNFSF14, HVEM and LTβR, were expressed in biopsies from all patients. The most prominent expression was seen within inflammatory infiltrates. Expression of LIGH, HVEM and LTβR correlated significantly with the intensity of fibrosis and duration of the disease. In multivariate analysis only LIGHT showed a significant relationship with fibrosis (β coefficient = 0.759, p = 0.02). There was no significant correlation between expression of any molecule and other demographic or clinical features.

Conclusion

We assume that LIGHT along with its receptors may be a factor contributing to fibrosis and synechiae formation in the lacrimal sac. This assumption needs to be proven in a future study in a group of patients who fail to improve after the first operation.

The prognostic value of platelet-to-lymphocyte ratio on the long-term renal survival in patients with IgA nephropathy

Purpose

Platelet-to-lymphocyte ratio (PLR) was established showing the poor prognosis in several diseases, such as malignancies and cardiovascular diseases. But limited study has been conducted about the prognostic value of PLR on the long-term renal survival of patients with Immunoglobulin A nephropathy (IgAN).

Methods

We performed an observational cohort study enrolling patients with biopsy-proven IgAN recorded from November 2011 to March 2016. The definition of composite endpoint was eGFR decrease by 50%, eGFR < 15 mL/min/1.73 m², initiation of dialysis, or renal transplantation. Patients were categorized by the magnitude of PLR tertiles into three groups. The Kaplan–Meier curves and multivariate Cox models were performed to determine the association of PLR with the renal survival of IgAN patients.

Results

330 patients with a median age of 34.0 years were followed for a median of 47.4 months, and 27 patients (8.2%) had reached the composite endpoints. There were no differences among the three groups (PLR < 106, 106 ≤ PLR ≤ 137, and PLR > 137) in demographic characteristics, mean arterial pressure (MAP), proteinuria, and estimated glomerular filtration rate (eGFR) at baseline. The Kaplan–Meier curves showed that the PLR > 137 group was significantly more likely to poor renal outcomes than the other two groups. Using univariate and multivariate cox regression analyses, we found that PLR > 137 was an independent prognostic factor for poor renal survival in patients with IgAN. Subgroup analysis revealed that the PLR remained the prognostic value for female patients or patients with eGFR less than 60 mL/min/1.73 m².

Conclusions

Our results underscored that baseline PLR was an independent prognostic factor for poor renal survival in patients with IgAN, especially for female patients or those patients with baseline eGFR less than 60 mL/min/1.73 m².

LIGHT aggravates sepsis-associated acute kidney injury via TLR4-MyD88-NF-κB pathway

Sepsis‐associated acute kidney injury (SA‐AKI) is a common clinical critical care syndrome. It has received increasing attention due to its high morbidity and mortality; however, its pathophysiological mechanisms remain elusive. LIGHT, the 14th member of the tumour necrosis factor (TNF) superfamily and a bidirectional immunoregulatory molecule that regulates inflammation, plays a pivotal role in disease pathogenesis. In this study, mice with an intraperitoneal injection of LPS and HK‐2 cells challenged with LPS were employed as a model of SA‐AKI in vivo and in vitro, respectively. LIGHT deficiency notably attenuated kidney injury in pathological damage and renal function and markedly mitigated the inflammatory reaction by decreasing inflammatory mediator production and inflammatory cell infiltration in vivo. The TLR4‐Myd88‐NF‐κB signalling pathway in the kidney of LIGHT knockout mice was dramatically down‐regulated compared to the controls. Recombinant human LIGHT aggravated LPS‐treated HK‐2 cell injury by up‐regulating the expression of the TLR4‐Myd88‐NF‐κB signalling pathway and inflammation levels. TAK 242 (a selective TLR4 inhibitor) reduced this trend to some extent. In addition, blocking LIGHT with soluble receptor fusion proteins HVEM‐Fc or LTβR‐Fc in mice attenuated renal dysfunction and pathological damage in SA‐AKI. Our findings indicate that LIGHT aggravates inflammation and promotes kidney damage in LPS‐induced SA‐AKI via the TLR4‐Myd88‐NF‐κB signalling pathway, which provide potential strategies for the treatment of SA‐AKI.

The Role of Immune Modulation in Pathogenesis of IgA Nephropathy

IgA nephropathy (IgAN) is the most prevalent primary glomerulonephritis worldwide, with diverse clinical manifestations characterized by recurrent gross hematuria or microscopic hematuria, and pathological changes featuring poorly O-galactosylated IgA1 deposition in the glomerular mesangium. Pathogenesis has always been the focus of IgAN studies. After 50 years of research, most scholars agree that IgAN is a group of clinicopathological syndromes with certain common immunopathological characteristics, and multiple mechanisms are involved in its pathogenesis, including immunology, genetics, and environmental or nutritional factors. However, the precise pathogenetic mechanisms have not been fully determined. One hypothesis about the pathogenesis of IgAN suggests that immunological factors are engaged in all aspects of IgAN development and play a critical role. A variety of immune cells (e.g., dendritic cells, NK cells, macrophages, T-lymphocyte subsets, and B-lymphocytes, etc.) and molecules (e.g., IgA receptors, Toll-like receptors, complements, etc.) in innate and adaptive immunity are involved in the pathogenesis of IgAN. Moreover, the abnormality of mucosal immune regulation is the core of IgAN immunopathogenesis. The roles of tonsil immunity or intestinal mucosal immunity, which have received more attention in recent years, are supported by mounting evidence. In this review, we will explore the latest research insights on the role of immune modulation in the pathogenesis of IgAN. With a better understanding of immunopathogenesis of IgAN, emerging therapies will soon become realized.

Crescentic IgA nephropathy after administration of human monoclonal interleukin-12/23p40 antibody in a patient with Crohn's disease: a case report

Ustekinumab (UST), an interleukin (IL)-12/IL-23-blocking monoclonal antibody, is a novel therapeutic option for Crohn's disease (CD). We describe a 24-year-old man with CD who showed an abrupt decline in renal function after administration of UST. Twenty-nine months previously, the patient was diagnosed with CD, and abnormal urinalysis findings in health checkup were coincidentally found at that time. Three months previously, treatment for CD was switched from infliximab to UST because of therapy-resistant severe diarrhea and bloody stools. A single dose of UST (260 mg) was initially intravenously administered, followed by single subcutaneous administration (90 mg) 2 months later. Thereafter, the patient exhibited rapid renal dysfunction with significant urinary abnormalities, although his gastrointestinal symptoms had completely disappeared. He was admitted to our hospital for further examination and treatment. Renal pathologic findings were compatible with crescentic glomerulonephritis consisting of almost fibro-cellular crescents. Immunofluorescent study showed IgA and C3 deposition in the glomerular mesangial area and IgA subclass staining revealed predominant IgA1 with concomitant mild IgA2 deposition. Furthermore, galactose-deficient IgA1 (Gd-IgA1) was also positive in the mesangial area. In addition, serum-Gd-IgA1 level was moderately increased. UST treatment was stopped and he responded to intensive steroid therapy with a parallel reduction of serum creatinine and Gd-IgA1 levels without flare of gastrointestinal symptoms. To our knowledge, this is the first case of immunoglobulin A nephropathy (IgAN) in patient with CD that might be aggravated by UST treatment. We presume that inhibition of IL-12/23 signaling with UST may cause to form crescentic IgAN by enhancing Gd-IgA1 production.

Role of prognostic biomarker decoy receptor 3 and immunomodulation in kidney diseases

Decoy receptor 3 (DcR3), also known as tumor necrosis factor receptor superfamily member 6b (TNFRSF6B), was recently identified as a novel biomarker for predicting progression of kidney diseases with potential immune modulation. The purpose of this review is to discuss the current evidence related to DcR3 in kidney diseases and to compare the differences between human and animal studies both in vivo and in vitro. High serum DcR3 predicts the occurrence of peritonitis in patients receiving chronic peritoneal dialysis and is positively correlated with inflammatory markers such as interleukin-6, high-sensitivity C-reactive protein, and adhesion molecules in patients on maintenance hemodialysis (HD). Higher serum DcR3 levels not only independently predict cardiovascular and all-cause mortality in HD patients but also identify older adults on HD at risk of protein-energy wasting in combination with a low geriatric nutritional risk index. Recently, renal tubular epithelial cells (RTECs) expressing DcR3 have also been used to predict progression of chronic kidney disease. Expression of DcR3 was correlated with a 2-fold increase in serum creatinine or failure of kidney allograft. DcR3 could protect renal myofibroblasts against Fas-induced apoptosis and subsequently lead to renal fibrosis. Locally expressed DcR3 in the RTECs may suppress the FasL-Fas-mediated apoptosis of T cells, resulting in an accumulation of allo-reactive T cells. In addition to traditional biological functions, recombinant DcR3.Fc and cytomegalovirus promoter-driven human DcR3 plasmid are able to modulate the activation and differentiation of dendritic cells and macrophages via "non-decoy" action. Both progressive IgA nephropathy and autoimmune crescentic glomerulonephritis in mice can be suppressed after hydrodynamics-based gene delivery of DcR3 plasmid. DcR3-mediated effects in vitro could be surveyed via over-expressing DcR3 or addition of recombinant DcR3.Fc, and CD68-driven DcR3 transgenic mice are suitable for investigating systemic effect in vivo. Inhibition of DcR3 expression in human may be a promising approach for pathomechanism.

[Renal and Urinary Manifestations of Inflammatory Bowel Disease]

The incidence of inflammatory bowel disease (IBD) is increasing rapidly and extra-intestinal manifestations in IBD are also increasing. The prevalence of renal and urinary involvement in IBD ranges from 4-23%. Nephrolithiasis is the most common urinary complication in IBD patients. Parenchymal renal disease is rare but has been well documented and presents most commonly as glomerulonephritis or tubulointerstitial nephritis. The overall morbidity of IBD-related renal manifestations is significant. Therefore, a high index of clinical suspicion and optimal monitoring of the renal function are needed for the early diagnosis and prevention of IBD-related renal manifestations and complications.

Murine Models of Human IgA Nephropathy

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis in the world. IgAN is characterized by mesangial deposits of IgA1-containing immune complexes. IgA1 usually co-deposits with complement C3 and variable IgG and/or IgM. Exactly 50 years have passed since IgAN was described, however, the pathogenesis of disease onset and progression have not been fully clarified. Animal models can re-create the complex immunologic microenvironments that foster human autoimmunity and nephritis and provide access to tissue compartments not readily examined in patients. Thus, multiple models that may be helpful in studies of specific aspects of IgAN have been developed. A unique spontaneous animal model of IgAN, the ddY mouse, was reported in 1985. These mice show mild proteinuria and glomerular IgA deposits, with a highly variable incidence and degree of glomerular injury owing to a heterogeneous genetic background. Thus, we intercrossed an early onset group of ddY mice in which the development of IgAN resulted in the establishment of a novel 100% early onset-grouped ddY mouse model with increased levels of aberrantly glycosylated IgA and immune complexes. Although the molecular features of human IgA1 are different from rodent IgA, human IgA1 knock-in (α1KI)-CD89 transgenic mice, which express both human IgA1 and CD89, show circulating and mesangial deposits of IgA1-soluble CD89 complexes that result in kidney inflammation, hematuria, and proteinuria. In this review, we introduce several murine models of IgAN that can be useful tools for the analysis of multiple aspects of the pathogenesis of IgAN, which may aid in the assessment of approaches for the treatment of IgAN.

Herpes Simplex Virus 1 Latency and the Kinetics of Reactivation Are Regulated by a Complex Network of Interactions between the Herpesvirus Entry Mediator, Its Ligands (gD, BTLA, LIGHT, and CD160), and the Latency-Associated Transcript

Recently, we reported that the herpesvirus entry mediator (HVEM; also called TNFRSF14 or CD270) is upregulated by the latency-associated transcript (LAT) of herpes simplex virus 1 (HSV-1) and that the absence of HVEM affects latency reactivation but not primary infection in ocularly infected mice. gD has been shown to bind to HVEM. LIGHT (TNFSF14), CD160, and BTLA (B- and T-lymphocyte attenuator) also interact with HVEM and can interfere with HSV gD binding. It was not known if LIGHT, CD160, or BTLA affected the level of latency reactivation in the trigeminal ganglia (TG) of latently infected mice. To address this issue, we ocularly infected LIGHT^-/-, CD160^-/-, and BTLA^-/- mice with LAT(+) and LAT(-) viruses, using similarly infected wild-type (WT) and HVEM^-/- mice as controls. The amount of latency, as determined by the levels of gB DNA in the TG of the LIGHT^-/-, CD160^-/-, and BTLA^-/- mice infected with either LAT(+) or LAT(-) viruses, was lower than that in WT mice infected with LAT(+) virus and was similar in WT mice infected with LAT(-) virus. The levels of LAT RNA in HVEM^-/-, LIGHT^-/-, CD160^-/-, and BTLA^-/- mice infected with LAT(+) virus were similar and were lower than the levels of LAT RNA in WT mice. However, LIGHT^-/-, CD160^-/-, and BTLA^-/- mice, independent of the presence of LAT, had levels of reactivation similar to those of WT mice infected with LAT(+) virus. Faster reactivation correlated with the upregulation of HVEM transcript. The LIGHT^-/-, CD160^-/-, and BTLA^-/- mice had higher levels of HVEM expression, and this, along with the absence of BTLA, LIGHT, or CD160, may contribute to faster reactivation, while the absence of each molecule, independent of LAT, may have contributed to lower latency. This study suggests that, in the absence of competition with gD for binding to HVEM, LAT RNA is important for WT levels of latency but not for WT levels of reactivation.IMPORTANCE The effects of BTLA, LIGHT, and CD160 on latency reactivation are not known. We show here that in BTLA, LIGHT, or CD160 null mice, latency is reduced; however, HVEM expression is upregulated compared to that of WT mice, and this upregulation is associated with higher reactivation that is independent of LAT but dependent on gD expression. Thus, one of the mechanisms by which BTLA, LIGHT, and CD160 null mice enhance reactivation appears to be the increased expression of HVEM in the presence of gD. Thus, our results suggest that blockade of HVEM-LIGHT-BTLA-CD160 contributes to reduced HSV-1 latency and reactivation.

Renal Manifestations of Inflammatory Bowel Disease

Renal and urinary involvement has been reported to occur in 4% to 23% of inflammatory bowel disease (IBD) patients. Parenchymal renal disease is rare and most commonly affects glomerular and tubulointerstitial compartments. The most common findings on renal biopsy of IBD patients are IgA nephropathy and tubulointerstitial nephritis. Overall morbidity of IBD-related renal manifestations is significant, and there is often only a short window of injury reversibility. This, along with subtle clinical presentation, requires a high index of suspicion and routine monitoring of renal function. There are no established guidelines for the optimal screening and monitoring of renal function in IBD patients.

The gut-kidney axis in IgA nephropathy: role of microbiota and diet on genetic predisposition

Recent data suggest that gut-associated lymphoid tissue (GALT) plays a major role in the development of immunoglobulin A (IgA) nephropathy (IgAN). A genome-wide association study showed that most loci associated with the risk of IgAN are also associated with immune-mediated inflammatory bowel diseases, maintenance of the intestinal barrier and regulation of response to gut pathogens. Studies involving experimental models have demonstrated a pivotal role of intestinal microbiota in the development of IgAN in mice producing high levels of IgA and in transgenic mice overexpressing BAFF, a B-cell factor crucial for IgA synthesis, indicating the role of genetic background, B-cell activity, GALT intestinal immunity and diet. The effect of diet was suggested by pilot studies carried out 30 years ago which showed that a gluten-rich diet induced IgAN in mice and that some patients benefited from a gluten-free diet. A recent experimental model in mice expressing human IgA1 and Fc alpha receptor CD89 reported clinical and histological improvement after a gluten-free diet. Clinical observations have elicited new interest in GALT hyper-reactivity in IgAN patients. In a pilot study, a reduction in proteinuria was attained using an enteric controlled-release formulation of the corticosteroid budesonide targeted to the Peyer's patches at the ileocecal junction. This formulation was tested in the placebo-controlled NEFIGAN phase 2b trial, with a reduction in proteinuria after 9 months of treatment together with stabilization of renal function in patients with persistent proteinuria. In conclusion, the gut-kidney axis modulated by microbiota and diet is a promising target for focused treatment of IgAN in genetically predisposed patients at risk of progression.

LIGHT is increased in patients with coronary disease and regulates inflammatory response and lipid metabolism in oxLDL-induced THP-1 macrophages

Inflammation is critical for the progression of hyperlipidemia. Although the exact mechanism through which inflammation affects hyperlipidemia is not very clear, evidence suggests that the tumor necrosis factor superfamily member 14 (TNFSF14/LIGHT)LIGHT might regulate lipid metabolism. In this study we investigated the expression of LIGHT in patients with different stages of coronary disease. The expression of lipid metabolism-related enzymes and inflammation-related proteins were further explored in oxidized low-density lipoproteins (oxLDL)-induced THP-1 macrophages. We found that LIGHT is highly expressed and companied with severe inflammations in patients with coronary disease. LIGHT significantly enhanced inflammation response in oxLDL-induced THP-1 macrophages. We further demonstrated that LIGHT markedly decreased the levels of lipolytic genes and increased the expressions of lipogenic genes in oxLDL-induced THP-1 macrophages. In addition, our results showed that LIGHT exerts its pro-inflammatory and pro-lipogenesis roles through activating nuclear factor-kappa B (NF-κB) signaling pathway. Taken together our study has demonstrated that LIGHT NF-κB-dependently exacerbates inflammation response and promotes lipid accumulation, and provided a new potential target for treatment of hyperlipidemia-related disease.

Immunological phenotype of the murine Lrba knockout

Biallelic mutations in the human lipopolysaccharide responsive beige-like anchor (LRBA) gene lead to a primary immunodeficiency known as LRBA deficiency, characterized by a broad range of clinical manifestations including autoimmunity, organomegaly, hypogammaglobulinemia and recurrent infections. Considering the phenotypic heterogeneity in patients and the severity of the disease, our aim was to assess the role of LRBA in immune cells and to understand the underlying pathomechanisms through the study of a Lrba knockout (Lrba^-/-) mouse model. LRBA-deficient mice did not show severe clinical or immunological signs of disease, either at steady state under specific-pathogen-free conditions, after vaccination with T-dependent and T-independent antigens, or in the context of acute infections with lymphocytic choriomeningitis virus (LCMV) or Salmonella Typhimurium. Although Lrba^-/- mice were able to produce normal serum immunoglobulin M (IgM) and IgG and to mount a specific immune response after immunization, they showed elevated serum and secretory basal IgA levels. LRBA was dispensable for B- and T-cell development, as well as for in vitro B-cell proliferation, survival, isotype switching and plasmablast differentiation. Interestingly, Lrba^-/- mice displayed decreased cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) expression by regulatory T cells and activated conventional CD4⁺ and CD8⁺ T lymphocytes, reduced frequency of peritoneal B-1a cells along with diminished interleukin-10 production and increased percentages of T follicular helper cells in Peyer's patches, but without developing overt signs of autoimmunity. Our findings expand the role of LRBA in immune regulatory mechanisms previously reported in patients, and suggest a novel role in IgA production that is crucial for the protection of mucosal surfaces and gut-associated immune tolerance.

LIGHT/TNFSF14 is increased in patients with type 2 diabetes mellitus and promotes islet cell dysfunction and endothelial cell inflammation in vitro

AIMS/HYPOTHESIS

Activation of inflammatory pathways is involved in the pathogenesis of type 2 diabetes mellitus. On the basis of its role in vascular inflammation and in metabolic disorders, we hypothesised that the TNF superfamily (TNFSF) member 14 (LIGHT/TNFSF14) could be involved in the pathogenesis of type 2 diabetes mellitus.

METHODS

Plasma levels of LIGHT were measured in two cohorts of type 2 diabetes mellitus patients (191 Italian and 40 Norwegian). Human pancreatic islet cells and arterial endothelial cells were used to explore regulation and relevant effects of LIGHT in vitro.

RESULTS

Our major findings were: (1) in both diabetic cohorts, plasma levels of LIGHT were significantly raised compared with sex- and age-matched healthy controls (n = 32); (2) enhanced release from activated platelets seems to be an important contributor to the raised LIGHT levels in type 2 diabetes mellitus; (3) in human pancreatic islet cells, inflammatory cytokines increased the release of LIGHT and upregulated mRNA and protein levels of the LIGHT receptors lymphotoxin β receptor (LTβR) and TNF receptor superfamily member 14 (HVEM/TNFRSF14); (4) in these cells, LIGHT attenuated the insulin release in response to high glucose at least partly via pro-apoptotic effects; and (5) in human arterial endothelial cells, glucose boosted inflammatory response to LIGHT, accompanied by an upregulation of mRNA levels of HVEM (also known as TNFRSF14) and LTβR (also known as LTBR).

CONCLUSIONS/INTERPRETATION

Our findings show that patients with type 2 diabetes mellitus are characterised by increased plasma LIGHT levels. Our in vitro findings suggest that LIGHT may contribute to the progression of type 2 diabetes mellitus by attenuating insulin secretion in pancreatic islet cells and by contributing to vascular inflammation.

TWEAK-Fn14 Signaling Activates Myofibroblasts to Drive Progression of Fibrotic Kidney Disease

The identification of the cellular origins of myofibroblasts has led to the discovery of novel pathways that potentially drive myofibroblast perpetuation in disease. Here, we further investigated the role of innate immune signaling pathways in this process. In mice, renal injury-induced activation of pericytes, which are myofibroblast precursors attached to endothelial cells, led to upregulated expression of TNF receptor superfamily member 12a, also known as fibroblast growth factor-inducible 14 (Fn14), by these cells. In live rat kidney slices, administration of the Fn14 ligand, TNF-related weak inducer of apoptosis (TWEAK), promoted pericyte-dependent vasoconstriction followed by pericyte detachment from capillaries. In vitro, administration of TWEAK activated and differentiated pericytes into cytokine-producing myofibroblasts, and further activated established myofibroblasts in a manner requiring canonical and noncanonical NF-κB signaling pathways. Deficiency of Fn14 protected mouse kidneys from fibrogenesis, inflammation, and associated vascular instability after in vivo injury, and was associated with loss of NF-κB signaling. In a genetic model of spontaneous CKD, therapeutic delivery of anti-TWEAK blocking antibodies attenuated disease progression, preserved organ function, and increased survival. These results identify the TWEAK-Fn14 signaling pathway as an important factor in myofibroblast perpetuation, fibrogenesis, and chronic disease progression.

The mucosa-kidney axis in IgA nephropathy

Links between IgA nephropathy (IgAN) and the mucosa have been recognized since the 1970s. In particular, the observation of visible haematuria induced by respiratory infections in patients with IgAN and the association of IgAN with diseases in which the mucosa plays a part, especially coeliac disease, have been taken as evidence of a mucosa-kidney axis. Here, we review current evidence that links the mucosa, in particular the gastrointestinal mucosa, and IgA produced by the bone marrow with IgAN. Genome-wide association studies in patients with IgAN have identified risk loci in genes involved in the intestinal mucosal integrity and immune network. Furthermore, the systemic immune response to mucosal antigens in IgAN is increased. Moreover, patients with IgAN have an increased reactivity to dietary proteins associated with subclinical intestinal mucosal inflammation. Associations between IgAN and gastrointestinal diseases have also been reported in a small number of patients, but whether these diseases share a common pathogenesis or whether gastrointestinal inflammation exacerbates IgAN is uncertain. Indeed, mucosal alterations such as infections could activate the innate immune system, aggravate a pre-existing IgAN and promote disease manifestations such as macrohaematuria. Various clinical interventions and trials targeting the mucosa or presumed mucosa-associated mechanisms have so far not yielded consistent findings and the results of ongoing trials are eagerly awaited.

Increased Serum Levels of LIGHT/TNFSF14 in Nonalcoholic Fatty Liver Disease: Possible Role in Hepatic Inflammation

OBJECTIVES

The tumor necrosis factor superfamily member 14, LIGHT (homologous to lymphotoxin, exhibits inducible expression, and competes with HSV glycoprotein D for herpes virus entry mediator (HVEM), a receptor expressed by T lymphocytes), has been involved in various autoimmune disorders and has been shown to influence hepatic lipid metabolism. We hypothesized that LIGHT could also have a pathogenic role in nonalcoholic fatty liver disease (NAFLD).

METHODS

Serum levels of LIGHT in NAFLD patients and control subjects, as well as LIGHT and interleukin (IL)-8 released from Huh7 (human hepatoma cell line) hepatocytes, were determined by enzyme-linked immunosorbent assay. The mRNA expression of LIGHT in the liver tissue and mRNA levels of LIGHT and IL-8 in Huh7 hepatocytes were assessed by real-time quantitative reverse transcription-PCR.

RESULTS

(i) Serum levels of LIGHT were significantly elevated in NAFLD patients (n=66) as compared with healthy controls (n=16), with no differences between simple steatosis (n=34) and nonalcoholic steatohepatitis (NASH) (n=32). (ii) Within the liver, NAFLD patients (n=14) had significantly increased mRNA levels of the two LIGHT receptors, herpes virus entry mediator and lymphotoxin β receptor (LTβR), as compared with controls (n=7), with no difference between simple steatosis (n=8) and NASH (n=6). (iii) LIGHT markedly increased the release of IL-8 in Huh7 hepatocytes in a time- and dose-dependent manner. (iv) The reactive oxygen species (ROS) H2O2 (hydrogen peroxide) enhanced the LIGHT-mediated release of IL-8 in Huh7 hepatocytes.

CONCLUSION

We show increased levels of LIGHT and its two membrane-bound receptors in NAFLD, potentially promoting hepatic inflammation through ROS interaction. Our findings should encourage further studies on the role of LIGHT in NAFLD development and progression.

Henoch-Schonlein purpura antecedent to Crohn's disease

We report a 13-year-old youth who initially presented with the typical rash of Henoch–Schonlein purpura followed a month later by a nephrotic syndrome and hematuria. Renal biopsy revealed crescentic IgA nephropathy. The patient was aggressively treated with steroids leading to a remission of his nephrotic syndrome. Three years after his initial presentation, he developed bloody diarrhea and Crohn’s disease was diagnosed.

Lymphotoxin β receptor signaling induces IL-8 production in human bronchial epithelial cells

Asthma-related mortality has been decreasing due to inhaled corticosteroid use, but severe asthma remains a major clinical problem. One characteristic of severe asthma is resistance to steroid therapy, which is related to neutrophilic inflammation. Recently, the tumor necrosis factor superfamily member (TNFSF) 14/LIGHT has been recognized as a key mediator in severe asthmatic airway inflammation. However, the profiles and intracellular mechanisms of cytokine/chemokine production induced in cells by LIGHT are poorly understood. We aimed to elucidate the molecular mechanism of LIGHT-induced cytokine/chemokine production by bronchial epithelial cells. Human bronchial epithelial cells express lymphotoxin β receptor (LTβR), but not herpesvirus entry mediator, which are receptors for LIGHT. LIGHT induced various cytokines/chemokines, such as interleukin (IL)-6, oncostatin M, monocyte chemotactic protein-1, growth-regulated protein α and IL-8. Specific siRNA for LTβR attenuated IL-6 and IL-8 production by BEAS-2B and normal human bronchial epithelial cells. LIGHT activated intracellular signaling, such as mitogen-activated protein kinase and nuclear factor-κB (NF-κB) signaling. LIGHT also induced luciferase activity of NF-κB response element, but not of activator protein-1 or serum response element. Specific inhibitors of phosphorylation of extracellular signal-regulated kinase (Erk) and that of inhibitor κB attenuated IL-8 production, suggesting that LIGHT-LTβR signaling induces IL-8 production via the Erk and NF-κB pathways. LIGHT, via LTβR signaling, may contribute to exacerbation of airway neutrophilic inflammation through cytokine and chemokine production by bronchial epithelial cells.

Re-thinking the functions of IgA(+) plasma cells

The intestinal mucosa harbors the largest population of antibody (Ab)-secreting plasma cells (PC) in the human body, producing daily several grams of immunoglobulin A (IgA). IgA has many functions, serving as a first-line barrier that protects the mucosal epithelium from pathogens, toxins and food antigens (Ag), shaping the intestinal microbiota, and regulating host-commensal homeostasis. Signals induced by commensal colonization are central for regulating IgA induction, maintenance, positioning and function and the number of IgA(+) PC is dramatically reduced in neonates and germ-free (GF) animals. Recent evidence demonstrates that the innate immune effector molecules tumor necrosis factor α (TNFα) and inducible nitric oxide synthase (iNOS) are required for IgA(+) PC homeostasis during the steady state and infection. Moreover, new functions ascribed to PC independent of Ab secretion continue to emerge, suggesting that PC, including IgA(+) PC, should be re-examined in the context of inflammation and infection. Here, we outline mechanisms of IgA(+) PC generation and survival, reviewing their functions in health and disease.

Roles of ligands from the TNF superfamily in B cell development, function, and regulation

Most ligands from the tumour necrosis factor (TNF) superfamily play very important roles in the immune system, and particularly so in B lymphocyte biology. TNF ligands are essential to many aspects of normal B cell biology from development in the bone marrow to maturation in the periphery as well as for activation and differentiation into germinal centre, memory or plasma cells. TNF ligands also influence other aspects of B cell biology such as their ability to present antigens or regulate immune responses. Importantly, inadequate regulation of many TNF ligands is associated with B cell disorders including autoimmunity and cancers. As a result, inhibitors of a number of TNF ligands have been tested in the clinic, with some becoming very successful approved treatments alleviating B cell-mediated pathologies.

Can tonsillectomy modify the innate and adaptive immunity pathways involved in IgA nephropathy?

The benefits of tonsillectomy in IgA nephropathy (IgAN) are still debated. Tonsillectomy may remove pathogen sources and reduce the mucosal associated lymphoid tissue (MALT), limiting degalactosylated IgA1 (deGal-IgA1) production, which is considered to be the initiating pathogenetic event leading to IgA glomerular deposition. In the European network VALIGA, 62/1147 IgAN patients underwent tonsillectomy (TxIgAN). In a cross-sectional study 15 of these patients were tested and compared to 45 non-tonsillectomized IgAN (no-TxIgAN) and healthy controls (HC) regarding levels of deGal-IgA1, and markers of innate immunity and oxidative stress, including toll-like receptors (TLR)2, 3, 4 and 9 mRNAs, proteasome (PS) and immunoproteasome (iPS) mRNAs in peripheral blood mononuclear cells (PBMC), and advanced oxidation protein products (AOPP). Levels of deGal-IgA1 were lower in TxIgAN than in no-TxIgAN (p = 0.015), but higher than in HC (p = 0.003). TLR mRNAs were more expressed in TxIgAN than in HC (TLR4, p = 0.021; TLR9, p = 0.027), and higher in TxIgAN than in no-TxIgAN (p ≤ 0.001 for TLR2, 4, 9). A switch from PS to iPS was detected in PBMC of TxIgAN in comparison to HC and it was higher than in no-TxIgAN [large multifunctional peptidase (LMP)2/β1, p = 0.039; LPM7/β5, p < 0.0001]. The levels of AOPP were significantly higher in TxIgAN than HC (p < 0.001) and no-TxIgAN (p = 0.033). In conclusion, the activation of innate immunity via TLRs and ubiquitin-proteasome pathways and the pro-oxidative milieu were not affected by tonsillectomy, even though the levels of aberrantly galactosylated IgA1 were lower in patients with IgAN who had tonsillectomy. The residual hyperactivation of innate immunity in tonsillectomized patients may result from extra-tonsillar MALT.

The histopathologic spectrum of kidney biopsies in patients with inflammatory bowel disease

BACKGROUND AND OBJECTIVES

Kidney disease as a complication of inflammatory bowel disease (IBD), including Crohn disease (CD) and ulcerative colitis (UC), has been the subject of case reports. However, no cases series examining IBD and kidney disease has been published to date. This study aimed to evaluate a large series of kidney biopsy specimens from patients with IBD to better define the spectrum and relative frequencies of IBD-associated kidney pathology.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective review of native kidney biopsy specimens obtained from March 2001 to June 2012 identified 83 patients with IBD. Standard processing of all biopsy specimens included light microscopy, immunofluorescence, and electron microscopy.

RESULTS

There were 45 cases of CD and 38 cases of UC represented. The most common indication for kidney biopsy was acute or chronic kidney failure (63% [52 of 83]) and nephrotic-range proteinuria (16% [13 of 83]). IgA nephropathy was the most common diagnosis (24% [20 of 83]), followed by interstitial nephritis (19% [16 of 83]), arterionephrosclerosis (12% [10 of 83]), acute tubular injury (8% [7 of 83]), proliferative GN (7% [6 of 83]), and minimal-change disease (5% [4 of 83]). When compared, the frequency of IgA nephropathy in IBD was significantly higher than in all other native renal biopsy specimens from the same time period (24% [20 of 83] versus 8% [2734 of 33,630]; P<0.001). Of the 16 cases of interstitial nephritis, 9 (56%) had current or recent past exposure to aminosalicylates, including all cases of granulomatous interstitial nephritis.

CONCLUSIONS

IBD is associated with a spectrum of kidney diseases most commonly affecting the glomerular and tubulointerstitial compartments. IgA nephropathy is the most frequent kidney biopsy diagnosis in IBD and has a significantly higher diagnostic prevalence compared with all non-IBD kidney biopsy specimens. This may reflect a common pathogenic mechanism. Although many cases of tubulointerstitial nephritis are related to aminosalicylate exposure, the possibility of a direct relationship with IBD cannot be ruled out.

New insights into the pathogenesis of IgA nephropathy

IgA nephropathy (IgAN) is the most common diagnosis amongst primary glomerular diseases in most countries where renal biopsies are regularly performed. Only a fraction of these patients is at high risk of losing glomerular filtration rate (GFR) in particular those with high grade proteinuria, uncontrolled hypertension or already impaired GFR at diagnosis, and those with renal scars in the renal biopsy. Genetic modifiers of IgAN onset and/or course are emerging. Spontaneous animal models of IgAN are problematic given considerable species differences between the rodent and human IgA system. However, new transgenic models help to better understand the pathogenesis. A key pathogenetic role appears to be played by underglycated IgA1 as well as autoantibodies to these IgA glycoforms and IgA receptors such as CD89 and transferrin receptor 1. Once IgA and/or IgA-containing immune complexes are deposited or formed in the mesangium, secondary effector mechanisms become important including complement activation, release of mesangial growth factors (in particular platelet-derived growth factor), and finally non-IgAN-specific events that culminate in glomerular and subsequently renal tubulointerstitial scaring. Here, we review these processes and describe potential novel therapeutic targets in IgAN.

Disruption of Smad4 expression in T cells leads to IgA nephropathy-like manifestations

The link between glomerular IgA nephropathy (IgAN) and T helper 2 (Th2) response has been implicated, however, the mechanisms are poorly defined because of the lack of an appropriate model. Here we report a novel murine model characterized by lineage-restricted deletion of the gene encoding MAD homologue 4 (Smad4) in T cells (Smad4(co/co;Lck-cre) ). Loss of Smad4 expression in T cells results in overproduction of Th2 cytokines and high serum IgA levels. We found that Smad4(co/co;Lck-cre) mice exhibited massive glomerular IgA deposition, increased albumin creatinine ratio, aberrant glycosylated IgA, IgA complexed with IgG1 and IgG2a, and polymeric IgA, all known features of IgAN in humans. Furthermore, we examined the β1, 4-galactosyltransferases (β4GalT) enzyme which is involved in the synthesis of glycosylated murine IgA, and we found reduced β4GalT2 and β4GalT4 mRNA levels in B cells. These findings indicate that Smad4(co/co;Lck-cre) mice could be a useful model for studying the mechanisms between IgAN and Th2 response, and further, disruption of Smad4-dependent signaling in T cells may play an important role in the pathogenesis of human IgAN and contributing to a Th2 T cell phenotype.

Neuronal and nonneuronal cholinergic structures in the mouse gastrointestinal tract and spleen

Accumulating evidence demonstrates that acetylcholine can directly modulate immune function in peripheral tissues including the spleen and gastrointestinal tract. However, the anatomical relationships between the peripheral cholinergic system and immune cells located in these lymphoid tissues remain unclear due to inherent technical difficulties with currently available neuroanatomical methods. In this study, mice with specific expression of the tdTomato fluorescent protein in choline acetyltransferase (ChAT)-expressing cells were used to label preganglionic and postganglionic cholinergic neurons and their projections to lymphoid tissues. Notably, our anatomical observations revealed an abundant innervation in the intestinal lamina propria of the entire gastrointestinal tract principally originating from cholinergic enteric neurons. The aforementioned innervation frequently approached macrophages, plasma cells, and lymphocytes located in the lamina propria and, to a lesser extent, lymphocytes in the interfollicular areas of Peyer's patches. In addition to the above innervation, we observed labeled epithelial cells in the gallbladder and lower intestines, as well as Microfold cells and T-cells within Peyer's patches. In contrast, we found only a sparse innervation in the spleen consisting of neuronal fibers of spinal origin present around arterioles and in lymphocyte-containing areas of the white pulp. Lastly, a small population of ChAT-expressing lymphocytes was identified in the spleen including both T- and B-cells. In summary, this study describes the variety of cholinergic neuronal and nonneuronal cells in a position to modulate gastrointestinal and splenic immunity in the mouse.

Tumor necrosis factor superfamily member LIGHT induces epithelial-mesenchymal transition in A549 human alveolar epithelial cells

Fibrosis is an abnormal response to organ injury, characterized by accumulation of activated fibroblasts at the sites of injury. Fibroblasts arise from several sources, including resident fibroblasts and circulating fibrocytes that infiltrate organ tissue. Recently, epithelial-mesenchymal transition (EMT) has been recognized as a source of mesenchymal cells. EMT is induced by various growth factors, such as transforming growth factor (TGF)-β1, and enhanced by inflammatory cytokines. Recently the tumor necrosis factor superfamily member LIGHT has been implicated in the pathogenesis of inflammatory disease and airway remodeling in severe asthma. We hypothesized that LIGHT might contribute to the pathogenesis of airway fibrosis via enhancement of EMT. Therefore, we investigated LIGHT's ability to induce EMT. A549 cells were stimulated with LIGHT, TGF-β1 or both for 48h. To estimate EMT, we evaluated the expression of epithelial and mesenchymal markers using immunocytochemistry, Western blotting and quantitative RT-PCR. Signaling pathways for EMT were characterized by Western analysis to detect phosphorylation of Erk1/2 and smad2. LIGHT enhanced TGF-β1-induced EMT both morphologically, by suppressing E-cadherin and enhancing vimentin, and functionally, by enhancing cell contractility. Additionally, LIGHT induced EMT without TGF-β1. Evaluation of the mechanism showed that LIGHT did not induce TGF-β1 production or affect the smad-snai1 pathway. Inhibition of Erk1/2 phosphorylation reduced LIGHT-induced EMT, indicating the Erk1/2 pathway to be a key pathway in LIGHT-induced EMT. In summary, LIGHT enhanced TGF-β1-induced EMT but also induced EMT via the Erk1/2 pathway by itself, without TGF-β1 signaling. LIGHT may contribute to the pathogenesis of airway fibrosis through enhancement of EMT.

The kinase TBK1 controls IgA class switching by negatively regulating noncanonical NF-κB signaling

Immunoglobulin class switching is crucial for the generation of antibody diversity in humoral immunity and, when deregulated, also has severe pathological consequences. How the magnitude of immunoglobulin isotype switching is controlled is still poorly understood. Here we identify the kinase TBK1 as a pivotal negative regulator of class switching to the immunoglobulin A (IgA) isotype. B cell-specific ablation of TBK1 in mice resulted in uncontrolled production of IgA and the development of nephropathy-like disease signs. TBK1 negatively regulated IgA class switching by attenuating noncanonical signaling via the transcription factor NF-κB, an action that involved TBK1-mediated phosphorylation and subsequent degradation of the NF-κB-inducing kinase NIK. Our findings establish TBK1 as a pivotal negative regulator of the noncanonical NF-κB pathway and identify a unique mechanism that controls IgA production.