Immune Complex-mediated Diseases Research Articles

Association of PTPN22 Gene Polymorphisms with Susceptibility to Juvenile Idiopathic Arthritis in Iranian Population

ABSTRACTJuvenile idiopathic arthritis (JIA), the most common cause of chronic arthritis in children, is a complex immune-mediated disease with considerable long-term morbidity and mortality. According to previous studies, PTPN22 gene has been associated with JIA in several populations. In the present study, we attempted to determine the association of PTPN22 single nucleotide polymorphisms (SNPs) with susceptibility to JIA in Iranian population. Using the Real-time PCR allelic discrimination method, samples consisting of 55 unrelated patients and 93 healthy controls were genotyped. Using Fisher exact test or Chi-square test, genotypic and allelic frequencies were estimated. The results of our study indicated a significantly decreased association of rs1310182 (OR = 0.59, 95% CI = 0.36 −0.97, p = 0.037) with JIA. This association may indicate a protective role for rs1310182 SNP against JIA. More research would be needed to elucidate the mechanistic role of this association.

Kidney Macrophages: Unique Position Solves a Complex Problem

Immune complex-mediated diseases, such as systemic lupus erythematosus, commonly affect the kidney and determine disease prognosis. Stamatiades etal. now propose a kidney-specific mechanism for trans-endothelial transport of small immune complexes that activate strategically positioned tissue resident macrophages.

IgE epitope proximity determines immune complex shape and effector cell activation capacity

BackgroundIgE-allergen complexes induce mast cell and basophil activation and thus immediate allergic inflammation. They are also important for IgE-facilitated allergen presentation to T cells by antigen-presenting cells.ObjectiveTo investigate whether the proximity of IgE binding sites on an allergen affects immune complex shape and subsequent effector cell activation in vitro and in vivo.MethodsWe constructed artificial allergens by grafting IgE epitopes in different numbers and proximity onto a scaffold protein. The shape of immune complexes formed between artificial allergens and the corresponding IgE was studied by negative-stain electron microscopy. Allergenic activity was determined using basophil activation assays. Mice were primed with IgE, followed by injection of artificial allergens to evaluate their in vivo allergenic activity. Severity of systemic anaphylaxis was measured by changes in body temperature.ResultsWe could demonstrate simultaneous binding of 4 IgE antibodies in close vicinity to each other. The proximity of IgE binding sites on allergens influenced the shape of the resulting immune complexes and the magnitude of effector cell activation and in vivo inflammation.ConclusionsOur results demonstrate that the proximity of IgE epitopes on an allergen affects its allergenic activity. We thus identified a novel mechanism by which IgE-allergen complexes regulate allergic inflammation. This mechanism should be important for allergy and other immune complex–mediated diseases.

The dichotomy between disease phenotype databases and the implications for understanding complex diseases involving the major histocompatibility complex.

Many genes related to innate and adaptive immunity reside within the major histocompatibility complex (MHC) and have been associated with a multitude of complex, immune-related disorders. Despite years of genetic study, this region has seen few causative determinants discovered for immune-mediated diseases. Reported associations have been curated in various databases including the Genetic Association Database, NCBI database of clinically relevant variants (ClinVar) and the Human Gene Mutation Database and together capture genetic associations and annotated pathogenic loci within the MHC and across the genome for a variety of complex, immune-mediated diseases. A review of these three distinct databases reveals disparate annotations between associated genes and pathogenic loci, alluding to the polygenic, multifactorial nature of immune-mediated diseases and the pleiotropic character of genes within the MHC. The technical limitations and inherent biases imposed by current approaches and technologies in studying the MHC create a strong case for the need to perform targeted deep sequencing of the MHC and other immunologically relevant loci in order to fully elucidate and study the causative elements of complex immune-mediated diseases.

Food for thought: progress in understanding the causes and mechanisms of food allergy.

The community burden of food allergy appears to be rising, yet the causes and mechanisms are not completely understood. The purpose of this review is to provide a snapshot of the state of play of IgE food allergies, with a focus on recent advances. There are still wide discrepancies regarding measures and definitions of food allergy. Even recent studies still rely on food sensitization, self-reporting, or parent-reporting rather than more robust measures. Population-based sampling strategies using objective measures are underway in some countries. Emerging data suggest substantial geographical and ethnic differences in food sensitization and allergy. Trans-cutaneous sensitization, particularly in those with eczema or filaggrin mutations, has been posited as a potential mechanism, as well as gut microbiota and genetics/epigenetics. Treatments for food allergy are still lacking, yet progress is being made, and immunotherapy appears more effective than dietary avoidance. Non-IgE food allergy remains drastically under-explored. Food allergy is a complex immune-mediated disease consisting of numerous environmental/genetic/epigenetic risk factors; yet interventions are likely to be simple and cost-effective.

Message from the editors: coeliac disease focused issue.

Message from the editors: coeliac disease focused issue.

Lipopolysaccharide induces inducible nitric oxide synthase-dependent podocyte dysfunction via a hypoxia-inducible factor 1α and cell division control protein 42 and Ras-related C3 botulinum toxin substrate 1 pathway

Urine protein loss in immune complex-mediated diseases such as lupus nephritis is associated with podocyte foot process effacement (podocytopathy) but is not always dependent on glomerular immune complex deposition. Several murine and human studies have associated lupus nephritis with inducible nitric oxide synthase (iNOS) expression in what appear to be podocytes. This study was conducted to determine mechanisms of immune-complex-independent and iNOS-dependent podocyte dysfunction. Conditionally immortalized podocytes were cultured with lipopolysaccharide (LPS) and nitric oxide (NO), superoxide (SO), or peroxynitrite donors in the presence or absence of inhibitors of iNOS, reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase or monocyte chemotactic protein 1 (MCP-1), or with sepiapterin to increase coupling of iNOS homodimers. Podocyte NO, SO, and MCP-1 production and nitrotyrosine modifications were determined. The podocytopathy phenotype was determined by measuring cell motility and membrane permeability to albumin. This study determined that NO produced by iNOS is sufficient and necessary to induce podocytopathy. NO probably induces this phenotype via hypoxia-inducible factor 1α and cell division control protein 42 and Ras-related C3 botulinum toxin substrate 1 pathways. With LPS stimulation, neither SO nor peroxynitrite produced by uncoupled iNOS or NADPH oxidase nor MCP-1 was sufficient to induce the full phenotype. This study supports the notion that iNOS may induce autocrine podocyte dysfunction. Thus, targeting iNOS or the pathways of its induction may have therapeutic benefit.

Genomewide admixture study in Mexican Mestizos with multiple sclerosis

BackgroundMultiple sclerosis (MS) is a complex immune-mediated disease. It has been suggested that genetic factors could explain differences in the prevalence among ethnic groups. To know whether genetic ancestry is a potential risk factor for MS in Mexican patients and to identify candidate genes for the susceptibility to the disease we conducted an initial trial of genome-wide analysis. Methods29 patients with diagnosis of definitive MS and 132 unrelated healthy controls were genotyped using the Affymetrix human 6.0 array. After QC procedures, ancestry determination and a preliminary case–control association study were performed. ResultsWe identified significant differences in the European ancestry proportion between MS cases and controls (33.1 vs 25.56, respectively; p=0.0045). Imputation analysis in the MHC region on chromosome 6 showed a signal with a significant level (p<0.00005) on the HLA-DRB region. Additionally, a preliminary association analysis highlighted the ASF1B as novel candidate gene participating in MS. ConclusionOur data suggest that European ancestry is a risk factor to develop MS in Mexican Mestizo population. Conversely, indigenous ancestry of Asian origin seems to confer protection. Further studies with more MS cases are needed to confirm these findings.

Current status of treatments for alopecia areata

Alopecia areata is a complex immune-mediated disease that targets anagen hair follicles.Treatment strategies are determined mainly according to patients' age,as well as the extent and duration of scalp involvement.Various therapeutic regimens have been described for alopecia areata,including corticosteroids,minoxidil,immunotherapy,biological agents,etc,but none of them is curative or preventive.Moreover,many of these therapeutic agents have not been subjected to randomized,controlled trials.The conquest of alopecia areata is still challenging.Now alopecia areata is considered to be an autoimmune disease with the loss of immune privilege in hair follicles.It is an ideal strategy to control alopecia areata through initial immunosuppression followed by reconstruction of the immune system. Key words: Alopecia areata; Therapeutic uses

Excessive activation of the alternative complement pathway in autosomal dominant polycystic kidney disease

The complement system is involved in many immune complex-mediated kidney diseases, yet its role in the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD) has not been examined in detail. Screening of the glycoproteome of urine samples from ADPKD patients revealed that levels of complement factor B (CFB), serpin peptidase inhibitor, complement component 1 inhibitor (SERPING1) and complement component 9 (C9) increased, whereas complement component 1, r subcomponent-like (C1RL), CD55 and CD59 levels decreased with disease progression. Immunostaining and Western blot analysis confirmed the enhanced expression of CFB and C9 in cystic kidneys from ADPKD patients. Immunostaining also showed that the expressions of CFB and C9 in renal biopsy tissues from patients with other types of chronic kidney disease were lower than in tissues from ADPKD patients. The effect of the complement inhibitor rosmarinic acid (RMA) was evaluated in Pkd1(-/-) mice and Han:SPRD Cy/+ rats. Compared with vehicle-treated Pkd1(-/-) animals, RMA-treated mice had significantly lower serum creatinine (-50%) and blood urea nitrogen (-78%) levels, two kidneys/body weight ratio (-60%) and renal cystic index (-60%). Similar results were found in Cy/+ rats. Lower numbers of Ki67-positive nuclei and inflammatory cells and reduced fibrosis were observed in both animal models upon treatment with RMA. These results suggest that excessive activation of the alternative complement pathway is associated with ADPKD progression, probably mediated by cyst-lining epithelial cell proliferation, tubulointerstitial inflammatory cell infiltration and fibrosis. Targeting the complement system might represent a new therapeutic strategy for ADPKD.

Neonatal Fc Receptor Promotes Immune Complex–Mediated Glomerular Disease

The neonatal Fc receptor (FcRn) is a major regulator of IgG and albumin homeostasis systemically and in the kidneys. We investigated the role of FcRn in the development of immune complex-mediated glomerular disease in mice. C57Bl/6 mice immunized with the noncollagenous domain of the α3 chain of type IV collagen (α3NC1) developed albuminuria associated with granular capillary loop deposition of exogenous antigen, mouse IgG, C3 and C5b-9, and podocyte injury. High-resolution imaging showed abundant IgG deposition in the expanded glomerular basement membrane, especially in regions corresponding to subepithelial electron dense deposits. FcRn-null and -humanized mice immunized with α3NC1 developed no albuminuria and had lower levels of serum IgG anti-α3NC1 antibodies and reduced glomerular deposition of IgG, antigen, and complement. Our results show that FcRn promotes the formation of subepithelial immune complexes and subsequent glomerular pathology leading to proteinuria, potentially by maintaining higher serum levels of pathogenic IgG antibodies. Therefore, reducing pathogenic IgG levels by pharmacologic inhibition of FcRn may provide a novel approach for the treatment of immune complex-mediated glomerular diseases. As proof of concept, we showed that a peptide inhibiting the interaction between human FcRn and human IgG accelerated the degradation of human IgG anti-α3NC1 autoantibodies injected into FCRN-humanized mice as effectively as genetic ablation of FcRn, thus preventing the glomerular deposition of immune complexes containing human IgG.

Systemic Lupus Erythematosus and Psoriasis: Comparison of Immunopathogenesis

Psoriasis and systemic lupus erythematosus (SLE) are complex immune-mediated diseases with burdens to patients and society. Recently, there has been considerable progress in understanding of autoimmunity, revealing critical roles for cytokine-mediated pathways that are common to both SLE and psoriasis. Ongoing pharmacogenomic and signaling studies coupled with clinical trials hold promise to better delineate overlaps and divergence in pathogenesis and lead to definition of biomarkers that can predict disease subsets, disease states, organ involvement and responsiveness to treatment. This review will compare SLE and psoriasis with regard to mutually relevant immune pathways and examine their significance as an influx of new biologic treatments comes into use.

Tissue-Derived Hedgehog Proteins Modulate Th Differentiation and Disease

Genome-wide association studies of complex immune-mediated diseases have indicated that many genetic factors, each with individual low risk, contribute to overall disease. It is therefore timely and important to characterize how immune responses may be subtly modified by tissue context. In this article, we explore the role of tissue-derived molecules in influencing the function of T cells, which, owing to their migratory nature, come into contact with many different microenvironments through their lifespan. Hedgehog (Hh) proteins act as secreted morphogens, providing concentration-dependent positional and temporal cell-fate specification in solid tissues. Hh signaling is required for embryogenesis and is important in postnatal tissue renewal and in malignancy. However, the function of Hh in dynamic, fluid systems, such as in mammalian immunity, is largely unknown. In this article, we show that Hh-dependent transcription in T cells promoted Th2 transcriptional programs and differentiation, exacerbating allergic disease. Of interest, expression of Sonic Hh increased in lung epithelial cells following the induction of allergic disease, and lung T cells upregulated Hh target gene expression, indicating that T cells respond to locally secreted Hh ligands in vivo. We show that Il4, the key Th2 cytokine, is a novel transcriptional target of Hh signals in T cells, providing one mechanism for the role of Hh in Th differentiation. We propose that Hh, secreted from inflamed, remodeling, or malignant tissue, can modulate local T cell function. Our data present an unexpected and novel role for tissue-derived morphogens in the regulation of fluid immune responses, with implications for allergy and tumor responses, suggesting new uses for anti-Hh therapeutics.

Tumor necrosis factor (TNF)-α gene +489 polymorphisms: association with psoriatic arthritis

Objective of this work was to investigate the role of single nucleotide polymorphisms (SNPs) at position +489 of the tumor necrosis factor (TNF)-α gene in generic susceptibility and severity of psoriatic arthritis (PsA). Fifty-seven Caucasian PsA patients diagnosed according to CASPAR criteria and 155 healthy matched controls were studied. PASI score, DAS28 and Disability INdex HAQ were calculated. Genomic DNA was extracted from peripheral blood samples and SNPs +489 G&amp;gt;A (rs 80267959) were amplified by PCR. The SNP +489 genotype was significantly associated with PsA susceptibility (p=0.0136) and severity of clinical and laboratory parameters (p values ranging from 0.016 to 2.908 x 10-12). The difference in severity was accounted for by the difference between the AA and GA genotypes with respect to the GG genotype. These findings suggest that TNF-α gene polymorphisms may influence PsA susceptibility and severity. Psoriatics arthritis (PsA) is a complex immunemediated disease that results from the interplay between multiple genetic and environmental factor [1]. Although the pathogenesis of PsA remains elusive, there is evidence that genetic factors may contribute to the etiology of the disease [2]. Is has been estimated that at least one third of the genetic contribution to PsA resides in the major histocompatibility complex (MHC) region [2]. The tumor necrosis factor (TNF)-α gene, which is located in the short arm of chromosome 6 in the MHC class III region between the HLA-B and HLA-DR genes, has been proposed as a major candidate gene in PsA [3]. This hypothesis is supported by studies which have found high serum, synovial fluid and synovial membrane TNF-α levels in patients with PsA [4,5]. Several single nucleotide polymorphisms (PNPs) have been identified in the TNF-α gene promoter [6]. In particular, two common polymorphisms, namely G to A substitutions at positions -238 and -308 have been studied in patients with PsA. However, association studies of these two TNF-α polymorphisms and genetic susceptibility to PsA have lead to conflicting results [7-12]. Previous studies have indicated the potential role of the SNP at +489 position in the first intron of the TNF-α gene in the susceptibility to some rheumatic autoimmune diseases like rheumatoid arthritis [13], systemic lupus erythematosus [14] and systemic sclerosis [15]. However, to our present knowledge, studies on the association of +489 polymorphism with PsA susceptibility and response to TNF-α inhibitors are not reported in the literature. Is this study we investigated the role of SNPs at +489 within the TNF-α gene in PsA susceptibility and severity.

Hepatitis C Virus - Proteins, Diagnosis, Treatment and New Approaches for Vaccine Development

Hepatitis C virus (HCV) causes acute and chronic human hepatitis infection and as such is an important global health problem. The virus was discovered in the USA in 1989 and it is now known that three to four million people are infected every year, WHO estimating that 3 percent of the 7 billion people worldwide being chronically infected. Humans are the natural hosts of HCV and this virus can eventually lead to permanent liver damage and carcinoma. HCV is a member of the Flaviviridae family and Hepacivirus genus. The diameter of the virus is about 50-60 nm and the virion contains a single-stranded positive RNA approximately 10,000 nucleotides in length and consisting of one ORF which is encapsulated by an external lipid envelope and icosahedral capsid. HCV is a heterogeneous virus, classified into 6 genotypes and more than 50 subtypes. Because of the genome variability, nucleotide sequences of genotypes differ by approximately 31-34%, and by 20-23% among subtypes. Quasi-species of mixed virus populations provide a survival advantage for the virus to create multiple variant genomes and a high rate of generation of variants to allow rapid selection of mutants for new environmental conditions. Direct contact with infected blood and blood products, sexual relationships and availability of injectable drugs have had remarkable effects on HCV epidemiology. Hundreds of thousands of people die each year from hepatitis and liver cancer caused by HCV virus infection. Approximately 80% of patients with acute hepatitis C progress into a chronic disease state leading to serious hepatic disorders, 10-20% of which develop chronic liver cirrhosis and hepatocellular carcinoma. The incubation period of HCV is 6-8 weeks and the infection is often asymptomatic so it is very hard to detect at early stages, making early treatment very difficult. Therefore, hepatitis C is called a "silent disease". Neutralizing antibodies are produced against several HCV proteins during infection but the virus mutates to escape from antibodies. Some patients with chronic hepatitis C may have some symptoms such as fatigue, muscle aches, nausea and pain. Autoimmune and immunecomplex-mediated diseases have also been reported with chronic HCV infection.

Epigenetics in inflammatory bowel disease

To briefly summarize some of the principles of epigenetics and assess their potential relevance for the disease pathogenesis of inflammatory bowel diseases (IBDs). To review the results of recent IBD-related epigenetic studies, discuss main challenges as well as highlight the opportunities for future research in this field. Evidence is accumulating for a major role of epigenetic mechanisms in the disease pathogenesis of several immune-mediated diseases. Recent findings indicate that epigenetics may mediate some of the effects of environment, genetic predisposition and intestinal microbiota on IBD pathogenesis. Epigenetics is a rapidly expanding and hugely promising area of research. At best, it may provide a unifying molecular mechanism to explain complex immune-mediated diseases such as IBD. Future research studies must be carefully designed, performed and analysed taking into account the basic principles of epigenetics in order to ensure the true potential of this field is realized in the understanding of IBD.

Detection of immunoglobulins and complement components in formalin fixed and paraffin embedded renal biopsy material by immunoflourescence technique

The technique of direct immunoflourescence (IF) is essential in the accurate diagnosis of renal glomerular diseases. The optimal results are obtained when the procedure is done on fresh frozen tissue (IF-F). However, techniques are available for IF study on formalin fixed and paraffin embedded (FFPE) renal biopsy specimens with variable reported success rates. We evaluated three such techniques on FFPE tissue and compared the results with those obtained by IF-F from the same patients. Heat treatment with Tris buffer and citrate buffer, and pronase treatment of the FFPE material was carried out. Direct IF was done for renal panel immunoglobulins and complement components on all biopsies and the results were compared with the historical IF-F study. When compared to the IF-F, the immunoflourescence staining on the paraffin sections was less sensitive and less intense in all immune complex-mediated renal diseases, but the diagnostic findings were detected in majority of the cases. In conclusion, it is possible to establish the diagnosis in most cases of immune complex-mediated glomerular diseases with IF on paraffin embedded tissue specimens.

Th17 and Interleukin 23 in the Pathogenesis of Psoriatic Arthritis and Spondyloarthritis

Psoriatic arthritis and spondyloarthritis (SpA) are complex immune-mediated diseases affecting peripheral and axial joints. T cells have been considered fundamental in triggering the disease and maintaining the process in the chronic phase. The recent discovery of the CD4+ Th17 lymphocyte subset and the interleukin 23/interleukin 17 axis has further contributed to the definition of unknown pathways, challenging previous models and the role of Th1/Th2 T cells in immune mediated diseases, including SpA.

Dietary-fat-induced taurocholic acid promotes pathobiont expansion and colitis in Il10-/- mice.

The composite human microbiome of Western populations has likely changed over the past century, brought on by new environmental triggers that often have a negative impact on human health1. Here we show that consumption of a diet high in saturated (milk derived)-fat (MF), but not polyunsaturated (safflower oil)-fat (PUFA), changes the conditions for microbial assemblage and promotes expansion of a low abundance, sulfite-reducing pathobiont, Bilophila wadsworthia2. This was associated with a pro-inflammatory TH1 immune response and increased incidence of colitis in genetically susceptible IL-10−/−, but not wild type mice. These effects are mediated by MF-promoted taurine-conjugation of hepatic bile acids, which increases the availability of organic sulfur used by sulfite-reducing microbes like B. wadsworthia. When mice were fed a low-fat (LF) diet supplemented with taurocholic, but not with glycocholic acid, for example, a bloom of B. wadsworthia and development of colitis were observed in IL10−/− mice. Together these data show that dietary fats, by promoting changes in host bile acid composition, can dramatically alter conditions for gut microbial assemblage, resulting in dysbiosis that can perturb immune homeostasis. The data provide a plausible mechanistic basis by which Western type diets high in certain saturated fats might increase the prevalence of complex immune-mediated diseases like inflammatory bowel diseases in genetically susceptible hosts.

Complement alternative pathway activation in the autologous phase of nephrotoxic serum nephritis

The complement cascade is an important part of the innate immune system, but pathological activation of this system causes tissue injury in several autoimmune and inflammatory diseases, including immune complex glomerulonephritis. We examined whether mice with targeted deletion of the gene for factor B (fB(-/-) mice) and selective deficiency in the alternative pathway of complement are protected from injury in the nephrotoxic serum (NTS) nephritis model of antibody-mediated glomerulonephritis. When the acute affects of the anti-glomerular basement membrane antibody were assessed, fB(-/-) mice developed a degree of injury similar to wild-type controls. If the mice were presensitized with sheep IgG or if the mice were followed for 5 mo postinjection, however, the fB(-/-) mice developed milder injury than wild-type mice. The immune response of fB(-/-) mice exposed to sheep IgG was similar to that of wild-type mice, but the fB(-/-) mice had less glomerular C3 deposition and lower levels of albuminuria. These results demonstrate that fB(-/-) mice are not significantly protected from acute heterologous injury in NTS nephritis but are protected from autologous injury in response to a planted glomerular antigen. Thus, although the glomerulus is resistant to antibody-initiated, alternative pathway-mediated injury, inhibition of this complement pathway may be beneficial in chronic immune complex-mediated diseases.