Comprehensive sequence analysis of the human IL23A gene defines new variation content and high rate of evolutionary conservation

C-Reactive Protein Controls IL-23 Production by Human Monocytes

C-reactive protein (CRP) is an acute-phase protein in humans that is produced in high quantities by the liver upon infection and under inflammatory conditions. Although CRP is commonly used as a marker of inflammation, CRP can also directly contribute to inflammation by eliciting pro-inflammatory cytokine production by immune cells. Since CRP is highly elevated in serum under inflammatory conditions, we have studied the CRP-induced cytokine profile of human monocytes, one of the main innate immune cell populations in blood. We identified that CRP is relatively unique in its capacity to induce production of the pro-inflammatory cytokine IL-23, which was in stark contrast to a wide panel of pattern recognition receptor (PRR) ligands. We show that CRP-induced IL-23 production was mediated at the level of gene transcription, since CRP particularly promoted gene transcription of IL23A (encoding IL-23p19) instead of IL12A (encoding IL-12p35), while PRR ligands induce the opposite response. Interestingly, when CRP stimulation was combined with PRR ligand stimulation, as for example, occurs in the context of sepsis, IL-23 production by monocytes was strongly reduced. Combined, these data identify CRP as a unique individual ligand to induce IL-23 production by monocytes, which may contribute to shaping systemic immune responses under inflammatory conditions.

Host Epigenetics in Intracellular Pathogen Infections

Some intracellular pathogens are able to avoid the defense mechanisms contributing to host epigenetic modifications. These changes trigger alterations tothe chromatin structure and on the transcriptional level of genes involved in the pathogenesis of many bacterial diseases. In this way, pathogens manipulate the host cell for their own survival. The better understanding of epigenetic consequences in bacterial infection may open the door for designing new vaccine approaches and therapeutic implications. This article characterizes selected intracellular bacterial pathogens, including Mycobacterium spp., Listeria spp., Chlamydia spp., Mycoplasma spp., Rickettsia spp., Legionella spp. and Yersinia spp., which can modulate and reprogram of defense genes in host innate immune cells.

Skin tissue expression and serum level of thymic stromal lymphopoietin in patients with psoriasis vulgaris

Thymic stromal lymphopoietin (TSLP) is known to be associated with allergic diseases. It is also suggested that TSLP has a role in autoimmune diseases such as psoriasis; however, the associated pathways remain unknown. There is currently little information on TSLP in psoriasis vulgaris. We investigated TSLP expressions on lesional and non-lesional skin of psoriasis vulgaris patients using reverse transcription- polymerase chain reaction. TSLP level was also investigated in serum from psoriasis vulgaris patients compared to healthy control using enzyme-linked immunosorbent assay. TSLP expression was higher in lesional skin (1.90) compared to non-lesional skin (1.76); however, the difference was not statistically significant (P>0.05). TSLP serum levels were significantly higher in psoriasis patients (287.40 pg/dL) as compared to controls (114.70 pg/dL) (P<0.05). This study concluded that TSLP levels in the serum of psoriasis vulgaris patients are higher than controls. TSLP was also found in keratinocyte of psoriasis patients, the expression was higher in the lesional compared to non-lesional skin; however, this difference is statistically insignificant. These findings suggest that TSLP may play a role in the pathogenesis of psoriasis vulgaris, but its exact role remains unclear.

Association of TNF, IL12, and IL23 gene polymorphisms and psoriatic arthritis: meta-analysis

BACKGROUND

Psoriatic arthritis (PsA) is a chronic skin and joint condition that considerably affects patient quality of life. Several studies have demonstrated different associations of genetic polymorphisms in the pathogenic process of PsA. Therefore, we conducted a meta-analysis to estimate the effect of polymorphisms in the cytokines TNF, IL12B, IL23A, and IL23R on PsA risk.

METHODS

We screened 1,097 abstracts and identified 14 relevant studies published between January 2007 and December 2017. A systematic search was conducted in PubMed, Web of Knowledge and Scopus databases. Meta-analyses were performed for the comparisons of alleles and multiple genetic models.

RESULTS

Among the cytokines studied, we found 17 polymorphisms that were the most investigated. The association to PsA was observed in the presence of polymorphisms: TNF-238 G > A (rs361525), -308 G > A (rs1800629), and -857 C > T (rs1799724); IL12B C > G (rs6887695) and A > C (rs3212227); IL23A A > G (rs2066808) and IL23R G > A (rs11209026).

CONCLUSION

Our findings suggest that these variant cytokine genes may strongly influence the immunological response of PsA.

Characterization of variations in IL23A and IL23R genes: possible roles in multiple sclerosis and other neuroinflammatory demyelinating diseases

Multiple sclerosis is among the most serious inflammatory demyelinating diseases (IDD). Interleukin-23A (IL23A) regulates and coordinates the activities of immune cells by interacting with its receptor IL23R and plays key roles in the pathogenesis of immune inflammatory diseases. IDD, deemed to be a kind of autoimmune diseases, may involve IL23A in the pathogenesis. The aim of this work was to validate the hypothesized involvement of IL-23A and its receptor in IDD. We sequenced the IL-23A and IL-23R genes for 206 Chinese Han IDD patients and evaluated SNPs within or near those genes. The serum levels of IL23A in IDD participants were analyzed using ELISA. The statistical analyses were conducted using Chi-Square Tests as implemented in SPSS (version 19.0). The Hardy-Weinberg equilibrium test of the population was carried out using online software OEGE. Three variants rs2066808, rs2371494, rs11575248 in IL-23A gene and one variant rs1884444 in IL-23R gene were demonstrated to be associated with the risk of MS or other IDD diseases, and the expression level of serum IL-23A in the MS patients was also altered. We conclude that variants in IL-23A and IL-23R genes were associated with the risk of MS or other IDD diseases.

The drug target genes show higher evolutionary conservation than non-target genes

Although evidence indicates that drug target genes share some common evolutionary features, there have been few studies analyzing evolutionary features of drug targets from an overall level. Therefore, we conducted an analysis which aimed to investigate the evolutionary characteristics of drug target genes. We compared the evolutionary conservation between human drug target genes and non-target genes by combining both the evolutionary features and network topological properties in human protein-protein interaction network. The evolution rate, conservation score and the percentage of orthologous genes of 21 species were included in our study. Meanwhile, four topological features including the average shortest path length, betweenness centrality, clustering coefficient and degree were considered for comparison analysis. Then we got four results as following: compared with non-drug target genes, 1) drug target genes had lower evolutionary rates; 2) drug target genes had higher conservation scores; 3) drug target genes had higher percentages of orthologous genes and 4) drug target genes had a tighter network structure including higher degrees, betweenness centrality, clustering coefficients and lower average shortest path lengths. These results demonstrate that drug target genes are more evolutionarily conserved than non-drug target genes. We hope that our study will provide valuable information for other researchers who are interested in evolutionary conservation of drug targets.

Genetic variation in the prostaglandin E2 pathway is associated with primary graft dysfunction

RATIONALE

Biologic pathways with significant genetic conservation across human populations have been implicated in the pathogenesis of primary graft dysfunction (PGD). The evaluation of the role of recipient genetic variation in PGD has thus far been limited to single, candidate gene analyses.

OBJECTIVES

We sought to identify genetic variants in lung transplant recipients that are responsible for increased risk of PGD using a two-phase large-scale genotyping approach.

METHODS

Phase 1 was a large-scale candidate gene association study of the multicenter, prospective Lung Transplant Outcomes Group cohort. Phase 2 included functional evaluation of selected variants and a bioinformatics screening of variants identified in phase 1.

MEASUREMENTS AND MAIN RESULTS

After genetic data quality control, 680 lung transplant recipients were included in the analysis. In phase 1, a total of 17 variants were significantly associated with PGD, four of which were in the prostaglandin E2 family of genes. Among these were a coding variant in the gene encoding prostaglandin E2 synthase (PTGES2; P = 9.3 × 10(-5)) resulting in an arginine to histidine substitution at amino acid position 298, and three variants in a block containing the 5' promoter and first intron of the PTGER4 gene (encoding prostaglandin E2 receptor subtype 4; all P < 5 × 10(-5)). Functional evaluation in regulatory T cells identified that rs4434423A in the PTGER4 gene was associated with differential suppressive function of regulatory T cells.

CONCLUSIONS

Further research aimed at replication and additional functional insight into the role played by genetic variation in prostaglandin E2 synthetic and signaling pathways in PGD is warranted.

Maximum-likelihood approaches reveal signatures of positive selection in IL genes in mammals

ILs are part of the immune system and are involved in multiple biological activities. ILs have been shown to evolve under positive selection; however, little information exists regarding which codons are specifically selected. By using different codon-based maximum-likelihood (ML) approaches, signatures of positive selection in mammalian ILs were searched for. Sequences of 46 ILs were retrieved from publicly available databases of mammalian genomes to detect signatures of positive selection in individual codons. Evolutionary analyses were conducted under two ML frameworks, the HyPhy package implemented in the Data Monkey Web Server and CODEML implemented in PAML. Signatures of positive selection were found in 28 ILs: IL-1A and B; IL-2, IL-4 to IL-10, IL-12A and B; IL-14 to IL-17A and C; IL-18, IL-20 to IL-22, IL-25, IL-26, IL-27B, IL-31, IL-34, IL-36A; and G. Codons under positive selection varied between 1 and 15. No evidence of positive selection was detected in IL-13; IL-17B and F; IL-19, IL-23, IL-24, IL-27A; or IL-29. Most mammalian ILs have sites evolving under positive selection, which may be explained by the multitude of biological processes in which ILs are enrolled. The results obtained raise hypotheses concerning the ILs functions, which should be pursued by using mutagenesis and crystallographic approaches.

Association study in Romanians confirms IL23A gene haplotype block rs2066808/rs11171806 as conferring risk to psoriatic arthritis

BACKGROUND

The cytokines IL12 and IL23 have been recently implicated in the pathogenesis of psoriatic arthritis (PsA). In this study we investigated the genetic variations in the genes coding for IL12, IL23 and IL23 receptor as a plausible source of susceptibility and modification of clinical symptoms of PsA in Romanian population.

METHODS

Twenty five SNPs mapping to IL12A, IL12B, IL23A, IL23R and IL12RB1 genes were genotyped in 94 PsA patients and 161 healthy controls of Romanian ethnicity using the Sequenom genotyping platform.

RESULTS

The exonic SNP rs11171806 from IL23A gene was significantly underrepresented in patients versus controls (p=0.03, OR 0.391) and the carriers of rs11171806/rs2066808 AC haplotype had decreased risk for PsA (p=0.03). The two SNPs of the highly conserved gene IL23A are in complete LD in our population. Genetic variants of IL12B gene were associated with polyarticular subtype of PsA. No associations were found between SNPs from IL12A, IL23R and IL12RB1 genes and susceptibility to PsA and its phenotypes.

CONCLUSION

We confirm the previously described association of rs2066808 variant with psoriasis and PsA and we show evidence of an extended genomic region inside IL23A gene as carrier of true disease susceptibility factors. These data suggest a role for IL23 in the PsA pathogenesis in Romanians.

Genetic variations in interleukin-12 related genes in immune-mediated diseases

The interleukin-12 (IL-12) family comprises a group of heterodimeric cytokines and their respective receptors that play key roles in immune responses. A growing number of autoimmune diseases has been found to be associated with genetic variation in these genes. Based on their respective associations with the IL-12 genes, autoimmune diseases appear to cluster in two groups that either show strong associations with the Th1/Th17 pathway (as indicated by genetic association with IL12B and IL23R) or the Th1/IL-35 pathway as the consequence of their association with polymorphisms in the IL12A gene region. The genetic associations are described in relation to what is known of the functionality of these genes in the various diseases. Comparing association data for gene families in different diseases may lead to better insight in the function of the genes in the onset and course of the disease.