No abstract

Leukocyte immunoglobulin (Ig)-like receptors (LILRs), also known as CD85 and immunoglobulin-like transcripts (ILTs), play pivotal roles in regulating immune responses. These receptors define an immune checkpoint that immune therapy can target. Through cis or trans interactions with human leukocyte antigen (HLA)-G, the two most abundantly expressed inhibitory LILRs, LILRB1, and LILRB2 (LILRB1/2, also known as CD85j/d and ILT2/4), are involved in immunotolerance in pregnancy and transplantation, autoimmune diseases, and immune evasion by tumors. Although the discrete domains of LILRB1/2 are clear, the assembly mode of the four extracellular Ig-like domains (D1, D2, D3, and D4) remains unknown. Previous data indicate that D1D2 is responsible for binding to HLA class I (HLA-I), but the roles of D3D4 are still unclear. Here, we determined the crystal structure of the four Ig-like domain LILRB2 and four-domain LILRB1 in complex with HLA-G1. The angles between adjacent domains and the staggered assembly of the four domains suggest limited flexibility and limited plasticity of the receptors during ligand binding. The complex structure of four-domain LILRB1 and HLA-G1 supports the model that D1D2 is responsible for HLA-I binding, while D3D4 acts as a scaffold. Accordingly, cis and trans binding models for HLA-I binding to LILRB1/2 are proposed. The geometries of LILRB1/2 in complex with dimeric and monomeric HLA-G1 suggest the accessibility of the dimeric receptor, which in turn, transduces more inhibitory signals. The assembly of LILRB1/2 and its binding to HLA-G1 could aid in the design of immune regulators and benefit immune interference.

The injury typically occurred after an overdose of NSAIDs. The risk factors include age older than 60 years, alcohol use, positive HBV markers, extracellular volume depletion and RAAS inhibitor combined use.

Objective No clear consensus has been reached on the PTPN22 R620W polymorphism and anti-neutrophil cytoplasmic antibody (ANCA) disease, especially when stratified by ANCA specificity and disease phenotypes. Methods A metaanalysis was conducted on the PTPN22 R620W polymorphism across 4 studies in 1399 white patients with ANCA disease and 9934 normal control subjects. Results Overall, metaanalysis showed a statistically significant association between the A allele and ANCA disease in all subjects (OR 1.44, 95% CI 1.26–1.64, p < 0.00001), and stratification by disease category indicated the A allele was associated with granulomatosis with polyangiitis (Wegener’s; GPA; OR 1.72, 95% CI 1.35–2.20, p < 0.0001) and microscopic polyangiitis (MPA; OR 1.53, 95% CI 1.08–2.15, p = 0.02) as compared to controls. However, when stratified by ANCA specificity, the association of the A allele was statistically evident among those with proteinase 3 (PR3) ANCA disease (OR 1.74, 95% CI 1.25–2.430, p = 0.001), with the same trend but not statistically associated with myeloperoxidase ANCA disease (OR 1.94, 95% CI 0.64–5.85, p = 0.24). The marked associations were also demonstrated between this allele with lung (OR 1.69, 95% CI 1.21–2.36, p = 0.002), ENT (OR 2.03, 95% CI 1.45–2.84, p < 0.0001), skin (OR 2.55, 95% CI 1.69–3.84, p < 0.0001), and peripheral neuropathy involvement (OR 2.12, 95% CI 1.39–3.22, p = 0.0005). Conclusion The PTPN22 620W allele confers susceptibility to the occurrence and development of ANCA disease in whites, with specific evidence among subsets with GPA, MPA, and PR3 ANCA. (J Rheumatol First Release Dec 1 2014; doi:10.3899/jrheum.131430)

Interleukin 1beta (IL-1beta) suppresses the IL-6-dependent induction of type II acute-phase response genes, but the underlying mechanism for this suppression remains uncertain. Here we report that treatment of human hepatocullular carcinoma HepG2 cells with IL-1beta inhibited the IL-6-dependent binding of signal transducer and activator of transcription factor (STAT)1, but not that of STAT3, to the high-affinity serum-inducible element ('SIE'). Furthermore, IL-1beta selectively down-regulated the IL-6-induced tyrosine phosphorylation of STAT1 without affecting the level of STAT1 or tyrosine phosphorylation of STAT3. Kinase assays in vitro indicated that the inhibition of STAT1 phosphorylation by IL-1beta was not due to an upstream blockade of Janus kinase (JAK1 or JAK2) activation. However, pretreatment with the proteasome inhibitor MG132 under conditions that prevented the IL-1beta-dependent activation of the nuclear factor NF-kappaB also blocked the inhibitory effect of IL-1beta on IL-6-activated STAT1. In related experiments, the protein tyrosine phosphatase inhibitor Na(3)VO(4) also antagonized the inhibitory effect of IL-1beta on the activation of STAT1 by IL-6. Taken together, these findings indicate that, by using a proteasome-dependent mechanism, IL-1beta concomitantly induces NF-kappaB activation and dephosphorylates IL-6-activated STAT1; the latter might partly account for the inhibition by IL-1beta of the IL-6-dependent induction of type II acute-phase genes.