SEMA3A, a gene involved in axonal pathfinding, is mutated in patients with Kallmann syndrome.

Kallmann syndrome (KS) associates congenital hypogonadism due to gonadotropin-releasing hormone (GnRH) deficiency and anosmia. The genetics of KS involves various modes of transmission, including oligogenic inheritance. Here, we report that Nrp1(sema/sema) mutant mice that lack a functional semaphorin-binding domain in neuropilin-1, an obligatory coreceptor of semaphorin-3A, have a KS-like phenotype. Pathohistological analysis of these mice indeed showed abnormal development of the peripheral olfactory system and defective embryonic migration of the neuroendocrine GnRH cells to the basal forebrain, which results in increased mortality of newborn mice and reduced fertility in adults. We thus screened 386 KS patients for the presence of mutations in SEMA3A (by Sanger sequencing of all 17 coding exons and flanking splice sites) and identified nonsynonymous mutations in 24 patients, specifically, a frameshifting small deletion (D538fsX31) and seven different missense mutations (R66W, N153S, I400V, V435I, T688A, R730Q, R733H). All the mutations were found in heterozygous state. Seven mutations resulted in impaired secretion of semaphorin-3A by transfected COS-7 cells (D538fsX31, R66W, V435I) or reduced signaling activity of the secreted protein in the GN11 cell line derived from embryonic GnRH cells (N153S, I400V, T688A, R733H), which strongly suggests that these mutations have a pathogenic effect. Notably, mutations in other KS genes had already been identified, in heterozygous state, in five of these patients. Our findings indicate that semaphorin-3A signaling insufficiency contributes to the pathogenesis of KS and further substantiate the oligogenic pattern of inheritance in this developmental disorder.

Protective effect of pristane on experimental autoimmune uveitis.

This study evaluates the effects of pristane and phytol, two mineral oils with pro-oxidative effects, on the course of experimental autoimmune uveitis. C57BL6 mice were immunized with IRBP1-20 peptide emulsified in CFA and treated five days prior to immunization with phytol or with pristane or with PBS as control. Administration of pristane reduces the incidence and severity of IRBP-induced uveitis as demonstrated by the decrease in vasculitis and inflammatory foci in fundus and by a reduction in histological damages and leukocyte infiltration compared to untreated or phytol-treated mice. The protective effect observed is associated with a decreased activation of peripheral CD4+ and CD8+ T lymphocytes and a decrease in the intensity of the Th1 and Th17 autoimmune response to IRBP in pristane-treated mice compared to control mice, as evidenced by the decreased production of IFNγ and IL17 by IRBP-specific lymphocytes from lymph nodes draining the site of immunization and by the increased production of anti-IRBP IgG1 over IgG2a. In addition, HUVEC and ARPE-19 cells incubated with the sera of mice treated with pristane presented a reduced production of H(2)O(2). The benefit of lowering the systemic oxidative stress by pristane in the course of EAU was confirmed by injecting the antioxidant NAC in IRBP-immunized mice. As pristane, NAC decreased clinical and histological inflammation of the retina and preserved the integrity of the hemato-retinal barrier. Finally, the protective effect of pristane on the development of EAU suggests that some mineral oils may represent a new therapeutic strategy in human uveitis.

Sialylation levels of anti-proteinase 3 antibodies are associated with the activity of granulomatosis with polyangiitis (Wegener's).

OBJECTIVE: To investigate whether the glycosylation and sialylation levels of anti-proteinase 3 (anti-PR3) antibodies could affect their pathogenicity, and whether these levels could be correlated with the activity of granulomatosis with polyangiitis (Wegener's) (GPA). METHODS: Forty-two serum samples positive for anti-PR3 antibodies from 42 patients with active or weakly active/inactive GPA were included. Anti-PR3 antibodies were assayed by enzyme-linked immunosorbent assay, and their levels of glycosylation and sialylation were assessed by enzyme-linked lectin assay. The glycosylation and sialylation levels of IgG purified from the serum of healthy donors and patients with active, remitted, or weakly active disease were assessed by permethylation and mass spectrometry analysis of glycans, following neuraminidase digestion. The neutrophil oxidative burst induced by purified IgG was assayed by spectrofluorimetry. RESULTS: The mean sialylation ratio of anti-PR3 antibodies was significantly lower in patients with active disease than in patients with weakly active or inactive disease, and this was inversely correlated with the Birmingham Vasculitis Activity Score (BVAS) (P < 0.0001). Similar results were obtained using the BVAS/GPA. The area under the receiver operating characteristic curve for the sialylation ratio of anti-PR3 antibodies, as a test to determine the activity of GPA, was 0.82 (P = 0.0006). The characterization of N-glycans showed a decrease in 2,6-linked sialylated N-glycans and an increase in dHex1 Hex3 HexNAc4 (mass/charge 1,836) agalactosylated structures in purified IgG from patients with active disease compared with controls. The anti-PR3 antibody-induced oxidative burst of neutrophils was inversely correlated with the sialylation levels of anti-PR3 IgG. CONCLUSION: The sialylation level of anti-PR3 antibodies contributes to the clinical activity of GPA, by modulating the oxidative burst of neutrophils induced by these autoantibodies.