The p.Arg435His Variation of IgG3 With High Affinity to FcRn Is Associated With Susceptibility for Pemphigus Vulgaris—Analysis of Four Different Ethnic Cohorts

IgG3 is the IgG subclass with the strongest effector functions among all four IgG subclasses and the highest degree of allelic variability among all constant immunoglobulin genes. Due to its genetic position, IgG3 is often the first isotype an antibody switches to before IgG1 or IgG4. Compared with the other IgG subclasses, it has a reduced half-life which is probably connected to a decreased affinity to the neonatal Fc receptor (FcRn). However, a few allelic variants harbor an amino acid replacement of His435 to Arg that reverts the half-life of the resulting IgG3 to the same level as the other IgG subclasses. Because of its functional impact, we hypothesized that the p.Arg435His variation could be associated with susceptibility to autoantibody-mediated diseases like pemphigus vulgaris (PV) and bullous pemphigoid (BP). Using a set of samples from German, Turkish, Egyptian, and Iranian patients and controls, we were able to demonstrate a genetic association of the p.Arg435His variation with PV risk, but not with BP risk. Our results suggest a hitherto unknown role for the function of IgG3 in the pathogenesis of PV

Nerve conduction velocity is regulated by the inositol polyphosphate-4-phosphatase II gene

Impairment of nerve conduction is common in neurodegenerative and neuroinflammatory diseases such as multiple sclerosis (MS), and measurement of evoked potentials (visual, motor, or sensory) has been widely used for diagnosis and recently also as a prognostic marker for MS. We used a classical genetic approach to identify novel genes controlling nerve conduction. First, we used quantitative trait mapping in F2 progeny of B10/SJL mice to identify EAE31, a locus controlling latency of motor evoked potentials (MEPs) and clinical onset of experimental autoimmune encephalomyelitis. Then, by combining congenic mapping, in silico haplotype analyses, and comparative genomics we identified inositol polyphosphate-4-phosphatase, type II (Inpp4b) as the quantitative trait gene for EAE31. Sequence variants of Inpp4b (C/A, exon 13; A/C, exon 14) were identified as differing among multiple mouse strains and correlated with individual cortical MEP latency differences. To evaluate the functional relevance of the amino acid exchanges at positions S474R and H548P, we generated transgenic mice carrying the longer-latency allele (Inpp4b(474R/548P)) in the C57BL/6J background. Inpp4b(474R/548P) mice exhibited significantly longer cortical MEP latencies (4.5 ± 0.22 ms versus 3.7 ± 0.13 ms; P = 1.04 × 10(-9)), indicating that INPP4B regulates nerve conduction velocity. An association of an INPP4B polymorphism (rs13102150) with MS was observed in German and Spanish MS cohorts (3676 controls and 911 cases) (P = 8.8 × 10(-3))

A family with atypical Hailey Hailey disease--is there more to the underlying genetics than ATP2C1?

The autosomal dominant Hailey Hailey disease (HHD) is caused by mutations in the ATP2C1 gene encoding for human secretory pathway Ca2+/Mn2+ ATPase protein (hSPCA1) in the Golgi apparatus. Clinically, HHD presents with erosions and hyperkeratosis predominantly in the intertrigines. Here we report an exome next generation sequencing (NGS) based analysis of ATPase genes in a Greek family with 3 HHD patients presenting with clinically atypical lesions mainly localized on the neck and shoulders. By NGS of one HHD-patient and in silico SNP calling and SNP filtering we identified a SNP in the expected ATP2C1 gene and SNPs in further ATPase genes. Verification in all 3 affected family members revealed a heterozygous frameshift deletion at position 2355_2358 in exon 24 of ATP2C1 in all three patients. 7 additional SNPs in 4 ATPase genes (ATP9B, ATP11A, ATP2B3 and ATP13A5) were identified. The SNPs rs138177421 in the ATP9B gene and rs2280268 in the ATP13A5 gene were detected in all 3 affected, but not in 2 non affected family members. The SNPs in the ATP2B3 and ATP11A gene as well as further SNPs in the ATP13A5 gene could not be confirmed in all affected family members. One may speculate that besides the level of functional hSPCA1 protein, levels of other ATPase proteins may influence expressivity of the disease and might also contribute, as in this case, to atypical presentations

Prospective studies on the routine use of a novel multivariant enzyme-linked immunosorbent assay for the diagnosis of autoimmune bullous diseases.

BACKGROUND Serologic diagnosis of autoimmune blistering disease (AIBD) usually follows a sophisticated multistep algorithm. OBJECTIVE We sought validation of a multivariant enzyme-linked immunosorbent assay (ELISA) in the routine diagnosis of AIBD. METHODS The multivariant ELISA comprising 6 recombinant immunodominant forms of major AIBD target antigens, ie, desmoglein 1, desmoglein 3, envoplakin, BP180, BP230, and type VII collagen was applied in: (1) a cohort of well-characterized AIBD (n = 173) and control sera (n = 130), (2) a prospective multicenter study with 204 sera from patients with newly diagnosed AIBD with positive direct immunofluorescence microscopy, and (3) a prospective monocenter study with 292 consecutive sera from patients with clinical suspicion of AIBD in comparison with the conventional multistep diagnostic algorithm. RESULTS Concordant results in the multivariant ELISA compared with direct immunofluorescence microscopy were seen in 94% of patients with pemphigus and 71% of patients with pemphigoid (Cohen κ value, 0.95 and 0.66) and with the conventional multistep diagnostic approach in 91% of patients with pemphigus and 88% of patients with bullous pemphigoid and 93% of autoantibody-negative sera (Cohen κ, 0.95, 0.84, and 0.78). LIMITATIONS IgA autoantibodies and less common target antigens were not analyzed. CONCLUSIONS The multivariant ELISA is a practical, highly standardized, and widely available novel diagnostic tool for the routine diagnosis of AIBD

Carboxypeptidase E Modulates Intestinal Immune Homeostasis and Protects against Experimental Colitis in Mice

<div><p>Enteroendocrine cells (EEC) produce neuropeptides, which are crucially involved in the maintenance of the intestinal barrier. Hence, EEC dysfunction is suggested to be involved in the complex pathophysiology of inflammatory bowel disease (IBD), which is characterized by decreased intestinal barrier function. However, the underlying mechanisms for EEC dysfunction are not clear and suitable models for a better understanding are lacking. Here, we demonstrate that Carboxypeptidase E (CPE) is specifically expressed in EEC of the murine colon and ileum and that its deficiency is associated with reduced intestinal levels of Neuropeptide Y (NPY) and Peptide YY (PYY), which are both produced by EEC. Moreover, <i>cpe^−/−</i> mice exhibit an aggravated course of DSS-induced chronic colitis compared to wildtype littermates. In addition, we observed elevated mucosal IL-6 and KC transcript levels already at baseline conditions in <i>cpe^−/−</i> mice. Moreover, supernatants obtained from isolated intestinal crypts of <i>cpe^−/−</i> mice lead to increased IL-6 and KC expression in MODE-K cells in the presence of LPS. This effect was reversible by co-administration of recombinant NPY, suggesting a CPE mediated immunosuppressive effect in the intestines by influencing the processing of specific neuropeptides. In this context, the chemotaxis of bone marrow derived macrophages towards respective supernatants was enhanced. In conclusion, our data point to an anti-inflammatory role of CPE in the intestine by influencing local cytokine levels and thus regulating the migration of myeloid immune cells into the mucosa. These findings highlight the importance of EEC for intestinal homeostasis and propose EEC as potential therapeutic targets in IBD.</p></div

Multicenter prospective study on multivariant diagnostics of autoimmune bullous dermatoses using the BIOCHIPTM technology.

BACKGROUND The current standard in the serological diagnosis of autoimmune bullous diseases (AIBD) is a multistep procedure sequentially applying different assays. In contrast, the BIOCHIPTM mosaic technology combines multiple substrates for parallel analysis by indirect immunofluorescence (IF). METHODS Sera from 749 consecutive, prospectively recruited, direct IF positive AIBD patients from 13 international study centers were analyzed independently and blinded using (i) a BIOCHIPTM mosaic including primate esophagus, salt-split skin, recombinant BP180 NC16A and gliadin GAF3x as well as HEK293 cells expressing recombinant desmoglein1, desmoglein3, type VII collagen, and BP230 C-terminus and (ii) the conventional multistep approach of the Department of Dermatology, University of Lübeck. RESULTS In 731 of 749 sera (97.6%) specific autoantibodies could be detected using the BIOCHIPTM mosaic, similar to the conventional procedure (725 cases, 96.8%). Cohens κ for both serological approaches ranged from 0.84 to 1.00. In 6.5% of sera, differences between the two approaches occurred and were mainly attributed to autoantigen fragments not present on the BIOCHIPTM mosaic. LIMITATIONS Laminin 332 and laminin γ1 are not represented on the BIOCHIPTM mosaic. CONCLUSIONS The BIOCHIPTM mosaic is a standardized, time- and serum-saving approach that further facilitates the serological diagnosis of AIBD

CPE deficiency aggravates experimental chronic colitis.

<p>(A) Calculation of the disease activity index (DAI) by determining clinical parameters of inflammation (body weight development, stool consistency, rectal bleeding) through 30 days of experimental colitis. n = 9 (<i>cpe</i>^+/+), n = 8 (<i>cpe</i>^−/−). (B-C) Determination of macroscopic colitis severity via mouse endoscopy. Representative endoluminal pictures of the distal colon on day 30 of experimental colitis (B) and calculation of the murine endoscopic index of colitis severity (MEICS) by analyzing mucosal morphology, stool consistency and shape of the vascular pattern via mouse endoscopy (C). n = 9 (<i>cpe</i>^+/+), n = 8 (<i>cpe</i>^−/−). (D–E) Determination of microscopic colitis severity via histology. Representative histological pictures of the distal colon on day 30 of experimental colitis (D) and calculation of the histology score by analyzing mucosal architecture and infiltration of immune cells (E). n = 8 per genotype. (F) Determination of expression level of TNF-α, IL-6 and KC in colonic punch biopsies by real time RT-PCR after 30 days of experimental colitis and at baseline. n = 8 per genotype. *p<0.05, **p<0.01, ***p<0.001 by t-test.</p