Objective. To identify susceptibility genes in a rat model of rheumatoid arthritis (RA) and to determine whether the corresponding human genes are associated with RA.Methods. Genes influencing oil-induced arthritis (OIA) were position mapped by comparing the susceptibility of inbred DA rats with that of DA rats carrying alleles derived from the arthritis-resistant PVG strain in chromosomal fragments overlapping the quantitative trait locus Oia2. Sequencing of gene complementary DNA (cDNA) and analysis of gene messenger RNA (mRNA) expression were performed to attempt to clone a causal gene. Associations with human RA were evaluated by genotyping single-nucleotide polymorphisms (SNPs) in the corresponding human genes and by analyzing frequencies of alleles and haplotypes in RA patients and age-, sex-, and area-matched healthy control subjects.Results. Congenic DA rats were resistant to OIA when they carried PVG alleles for the antigenpresenting lectin-like receptor gene complex (APLEC), which encodes immunoregulatory C-type lectin-like receptors. Multiple differences in cDNA sequence and mRNA expression precluded cloning of a single causal gene. Five corresponding human APLEC genes were identified and targeted. The SNP rs1133104 in the dendritic cell immunoreceptor gene (DCIR), and a haplotype including that marker and 4 other SNPs in DCIR and its vicinity showed an indication of allelic association with susceptibility to RA in patients who were negative for antibodies to cyclic citrullinated peptide (anti-CCP), with respective odds ratios of 1.27 (95% confidence interval [95% CI] 1.06-1.52; uncorrected P ‫؍‬ 0.0073) and 1.37 (95% CI 1.12-1.67; uncorrected P ‫؍‬ 0.0019). Results of permutation testing supported this association of the haplotype with RA.

Primary biliary cholangitis (PBC) is an autoimmune liver disease with a strong hereditary component. Here, we report a genome-wide association study that included 1,122 PBC cases and 4,036 controls of Han Chinese descent, with subsequent replication in a separate cohort of 907 PBC cases and 2,127 controls. Our results show genome-wide association of 14 PBC risk loci including previously identified 6p21 (HLA-DRA and DPB1), 17q12 (ORMDL3), 3q13.33 (CD80), 2q32.3 (STAT1/STAT4), 3q25.33 (IL12A), 4q24 (NF-κB) and 22q13.1 (RPL3/SYNGR1). We also identified variants in IL21, IL21R, CD28/CTLA4/ICOS, CD58, ARID3A and IL16 as novel PBC risk loci. These new findings and histochemical studies showing enhanced expression of IL21 and IL21R in PBC livers (particularly in the hepatic portal tracks) support a disease mechanism in which the deregulation of the IL21 signalling pathway, in addition to CD4 T-cell activation and T-cell co-stimulation are critical components in the development of PBC.

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Non-small cell lung cancers (NSCLC) marked by EGFR mutations tend to develop resistance to therapeutic EGFR inhibitors, often due to secondary mutation EGFRT790M but also other mechanisms. Here we report support for a rationale to target IKBKE, an IκB kinase family member which activates the AKT and NF-κB pathways, as one strategy to address NSCLC resistant to EGFR inhibitors. While wild-type and mutant EGFR directly interacted with IKBKE, only mutant EGFR phosphorylated IKBKE on residues Y153 and Y179. The unphosphorylatable mutant IKBKE-Y153F/Y179-F which lost kinase activity failed to activate AKT and inhibited EGFR signaling. In clinical specimens of NSCLC with activating mutations of EGFR, we observed elevated levels of phospho-Y153 IKBKE. IKBKE ablation with shRNA or small molecule inhibitor amlexanox selectively inhibited the viability of NSCLC cells with EGFR mutations in vitro. In parallel, we found that these treatments activated the MAPK pathway due to attenuation of an IKBKE feedback mechanism. In vivo studies revealed that combining amlexanox with MEK inhibitor AZD6244 significantly inhibited the xenograft tumor growth of NSCLC cells harboring activating EGFR mutations, including EGFRT790M. Overall, our findings define IKBKE as a direct effector target of EGFR and provide a therapeutic rationale to target IKBKE as a strategy to eradicate EGFR-TKI resistant NSCLC cells.

Objective. The antigen-presenting lectin-like receptor complex (APLEC) was recently identified as a genetic determinant for arthritis susceptibility. We undertook this study to define mechanisms underlying the impact of APLEC on arthritis, to determine whether sex effects occur, and to determine whether APLEC influences different types of arthritis and phenotypes other than susceptibility.Methods. Arthritis-susceptible DA rats were compared with sex-matched congenic rats in which APLEC alleles were substituted with alleles from arthritisresistant PVG rats. Six different arthritogenic agents were injected at the base of the tail: Freund's incomplete adjuvant, pristane, squalene, killed mycobacteria, yeast ␤-glucan, or rat type II collagen (CII). Arthritis was visually scored, body weight was measured, and anti-CII IgG and cytokine messenger RNA (mRNA) levels were determined by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction, respectively.Results. In 5 models of rheumatoid arthritis (RA), congenic rats deviated profoundly from DA rats by having reduced arthritis susceptibility, delayed onset, decreased severity, and/or reduced body weight loss. Paradoxical opposite genetic effects were noted, including a more severe disease course in congenic males in pristane-induced arthritis and decreased clinical signs in collagen-induced arthritis despite increased autoantibody levels. Interestingly, the anti-CII IgG isotype profile was skewed in congenic rats, and markedly reduced lymph node mRNA levels for interleukin-17 suggested that the cytokine profile of autoreactive T helper cells was also skewed in a less pathogenic direction.Conclusion. Rat APLEC regulates autoimmunity and multiple phenotypes in several types of arthritis. However, delineating the genetic impact may require stratification for sex or mode of arthritis induction. This pathogenetic complexity should be considered when evaluating APLEC in inflammatory and autoimmune diseases, including RA.

Genetic variation in the antigen-presenting lectin-like receptor gene complex (APLEC) associates with autoimmunity and arthritis in rats and humans. We hypothesized that the encoded C-type lectin-like receptors might influence innate immunity and responses to infectious agents. To test this hypothesis, we compared in vivo and in vitro phenotypes in DA rats and APLEC-congenic rats. Survival rates following infection with Staphylococcus aureus and Herpes simplex virus differed significantly between the two strains. Likewise, differential delayed type hypersensitivity (DTH), an immunological reaction involving T lymphocytes and macrophages, was observed in response to provocation with the chemical oxazolone. Unstimulated bone marrow-derived macrophages from the two strains appeared to already have polarized activation states with different mRNA levels of CD163 and Dectin-1 receptors. Following stimulation with a panel of microbial agents, differences in induced mRNA and protein levels were shown for interleukin (IL)-6 and IL-10 following stimulation with lipopolysaccharide, mannan and b-glucan. Expression levels of APLEC gene mRNAs also differed, and both strains had a notably dichotomous expression of the genes, with general downregulation of all four Dcir genes and upregulation of Mincle and Mcl. We suggest that human APLEC genes may similarly regulate infectious diseases, DTH and general macrophage activation status.