Interferon Regulatory Factor 5 Gene Polymorphisms and mRNA Expression Levels Are Associated with Neuromyelitis Optica Spectrum Disorder

Interferon regulatory factor 5 (IRF5) is a critical transcription factor in the toll-like receptor signaling pathway. It is associated with autoimmune disorders, such as rheumatoid arthritis, systemic lupus erythematosus, and inflammatory bowel disease. However, the relationship between the functional single nucleotide polymorphisms (SNPs) of IRF5 and its mRNA expression level in patients with neuromyelitis optica spectrum disorder remains unclear. The present study aimed to investigate the relationship between polymorphisms and mRNA expression levels of the IRF5 gene with the incidence of neuromyelitis optica spectrum disorder (NMOSD) in northern Chinese Han people. Two loci of the IRF5 gene (rs2004640 and rs2280714) of 164 patients with NMOSD and 269 healthy subjects were genotyped using the multiple SNaPshot technique. The frequencies of alleles, genotypes, and haplotypes were compared. Stratified analysis was performed according to age, sex, AQP4 status, onset age, and Expanded Disability Status Scale (EDSS) score. The IRF5 mRNA levels in peripheral blood mononuclear cells (PBMCs) of 64 NMOSD patients (32 patients in the acute stage and 32 patients in the remission stage) and 35 healthy subjects were detected by real-time PCR. The association of SNP polymorphisms with the mRNA expression level was determined by nonparametric tests. Allele and genotype frequency distributions of rs2004640 showed significant differences between both groups. Compared to healthy controls, the frequency of rs2004640 T allele markedly increased in patients (OR = 1.51, 95% CI = 1.09-2.08, P = 0.005). Minor allele T and GT genotype of rs2004640 that significantly increases the risk of NMOSD were discovered using genetic inheritance models (codominant, dominant, and overdominant) and haplotype analyses. Subsequent haplotype analyses revealed that the major haplotype "T-A" containing the risk alleles (the SNP sequence of the alleles was rs2004640 and rs2280714) had adverse effects on NMOSD. Based on the stratification analysis according to the EDSS score, the GT genotype frequency in the EDSS ≥ 4 group (38.2%) was markedly lower than that in the EDSS < 4 group (61.8%) (OR = 0.32, 95% CI = 0.15-0.68, P = 0.0054), with a significant difference. The IRF5 mRNA expression level was increased in NMOSD patients compared to that in normal subjects. IRF5 gene polymorphisms may be tightly associated with the genesis and progression of NMOSD in northern Chinese Han people. IRF5 mRNA expression was increased in patients with NMOSD and significantly increased in patients with acute phase. Perhaps IRF5 expression levels can be used as a predictor of disease activity in the future.

Sex differences in the percentage of IRF5 positive B cells are associated with higher production of TNF-α in women in response to TLR9 in humans

BACKGROUND

The clinical course and outcome of many diseases differ between women and men, with women experiencing a higher prevalence and more severe pathogenesis of autoimmune diseases. The precise mechanisms underlying these sex differences still remain to be fully understood. IRF5 is a master transcription factor that regulates TLR/MyD88-mediated responses to pathogen-associated molecular patterns (PAMPS) in DCs and B cells. B cells are central effector cells involved in autoimmune diseases via the production of antibodies and pro-inflammatory cytokines as well as mediating T cell help. Dysregulation of IRF5 expression has been reported in autoimmune diseases, including systemic lupus erythematosus, primary Sjögren syndrome, and rheumatoid arthritis.

METHODS

In the current study, we analyzed whether the percentage of IRF5 positive B cells differs between women and men and assessed the resulting consequences for the production of inflammatory cytokines after TLR7- or TLR9 stimulation.

RESULTS

The percentage of IRF5 positive B cells was significantly higher in B cells of women compared to men in both unstimulated and TLR7- or TLR9-stimulated B cells. B cells of women produced higher levels of TNF-α in response to TLR9 stimulation.

CONCLUSIONS

Taken together, our data contribute to the understanding of sex differences in immune responses and may identify IRF5 as a potential therapeutic target to reduce harmful B cell-mediated immune responses in women.

Frequency of IRF5+ dendritic cells is associated with the TLR7-induced inflammatory cytokine response in SARS-CoV-2 infection

The SARS-CoV-2 infection leads to enhanced inflammation driven by innate immune responses. Upon TLR7 stimulation, dendritic cells (DC) mediate the production of inflammatory cytokines, and in particular of type I interferons (IFN). Especially in DCs, IRF5 is a key transcription factor that regulates pathogen-induced immune responses via activation of the MyD88-dependent TLR signaling pathway. In the current study, the frequencies of IRF5+ DCs and the association with innate cytokine responses in SARS-CoV-2 infected individuals with different disease courses were investigated. In addition to a decreased number of mDC and pDC subsets, we could show reduced relative IRF5+ frequencies in mDCs of SARS-CoV-2 infected individuals compared with healthy donors. Functionally, mDCs of COVID-19 patients produced lower levels of IL-6 in response to in vitro TLR7 stimulation. IRF5+ mDCs more frequently produced IL-6 and TNF-α compared to their IRF5- counterparts upon TLR7 ligation. The correlation of IRF5+ mDCs with the frequencies of IL-6 and TNF-α producing mDCs were indicators for a role of IRF5 in the regulation of cytokine responses in mDCs. In conclusion, our data provide further insights into the underlying mechanisms of TLR7-dependent immune dysfunction and identify IRF5 as a potential immunomodulatory target in SARS-CoV-2 infection.

Depression Exacerbates Dextran Sulfate Sodium-Induced Colitis via IRF5-Mediated Macrophage Polarization

BACKGROUND AND AIMS

Patients with inflammatory bowel disease (IBD) and concurrent depression are predisposed to severer disease activity and a worse prognosis. Macrophage polarization toward the M1 phenotype may contribute to the exacerbation of IBD with comorbid depression. Moreover, interferon regulatory factor 5 (IRF5) is involved in the pathogenesis of IBD. The aim of this study was to explore the role of IRF5 in macrophage polarization in the impact of depression upon colitis.

METHODS

Depressive-like behavior was induced by repeated forced swim stress. Colon length, disease activity index (DAI), colon morphology, histology, ultrastructure of epithelial barrier, lamina propria macrophage polarization, and expression of IRF5 were compared between DSS colitis rats with and without depressive-like behavior. IRF5 shRNA was constructed to affect the rat peritoneal macrophages polarization in vitro. After IRF5 shRNA lentivirus was introduced into colon by enema, the colitis severity, lamina propria macrophage polarization, and TNF-α, IL-1β, and IL-10 of colon tissues were measured.

RESULTS

The study found severer colonic inflammation in depressed versus non-depressed DSS-colitis rats. Depressed DSS-colitis rats exhibited smaller subepithelial macrophages size and reduced intracellular granule diversity compared with nondepressed DSS-colitis rats. Increased polarization toward the M1 phenotype, elevated expression of IRF5, and co-expression of IRF5 with CD86 were found in depressed versus nondepressed DSS-colitis rats. Lentivirus-mediated shRNA interference with IRF5 expression switched rat peritoneal macrophage polarization from the M1 to the M2 phenotype, downregulated TNF-α, IL-1β expression to a greater extent in depressed versus nondepressed colitis rats.

CONCLUSIONS

IRF5-mediated macrophage polarization may likely underlie the deterioration of DSS-induced colitis caused by depression.

Myeloid cell-specific Irf5 deficiency stabilizes atherosclerotic plaques in Apoe-/- mice

OBJECTIVE

Interferon regulatory factor (IRF) 5 is a transcription factor known for promoting M1 type macrophage polarization in vitro. Given the central role of inflammatory macrophages in promoting atherosclerotic plaque progression, we hypothesize that myeloid cell-specific deletion of IRF5 is protective against atherosclerosis.

METHODS

Female Apoe-/-LysmCre/+Irf5fl/fl and Apoe-/-Irf5fl/fl mice were fed a high-cholesterol diet for three months. Atherosclerotic plaque size and compositions as well as inflammatory gene expression were analyzed. Mechanistically, IRF5-dependent bone marrow-derived macrophage cytokine profiles were tested under M1 and M2 polarizing conditions. Mixed bone marrow chimeras were generated to determine intrinsic IRF5-dependent effects on macrophage accumulation in atherosclerotic plaques.

RESULTS

Myeloid cell-specific Irf5 deficiency blunted LPS/IFNγ-induced inflammatory gene expression in vitro and in the atherosclerotic aorta in vivo. While atherosclerotic lesion size was not reduced in myeloid cell-specific Irf5-deficient Apoe-/- mice, plaque composition was favorably altered, resembling a stable plaque phenotype with reduced macrophage and lipid contents, reduced inflammatory gene expression and increased collagen deposition alongside elevated Mertk and Tgfβ expression. Irf5-deficient macrophages, when directly competing with wild type macrophages in the same mouse, were less prone to accumulate in atherosclerotic lesion, independent of monocyte recruitment. Irf5-deficient monocytes, when exposed to oxidized low density lipoprotein, were less likely to differentiate into macrophage foam cells, and Irf5-deficient macrophages proliferated less in the plaque.

CONCLUSION

Our study provides genetic evidence that selectively altering macrophage polarization induces a stable plaque phenotype in mice.

A promising role of interferon regulatory factor 5 as an early warning biomarker for the development of human non-small cell lung cancer

OBJECTIVES

Non-small cell lung cancer (NSCLC) accounts for 85%-90% of lung cancer cases and is a covert disease lacking early symptoms. Since cancer is recognised as an inflammation-associated condition, we analysed the relationship between the expression of interferon regulatory factor 5 (IRF5), a key transcription factor controlling inflammatory responses, and NSCLC development with the aim of identifying a warning biomarker for early diagnosis of the disease.

MATERIALS AND METHODS

The expression of IRF5 and its associated inflammatory factors IL-6, IL-10, IP-10, and TNF-α in the peripheral blood of NSCLC patients (n = 66) and healthy controls (n = 42) was analysed by quantitative RT-PCR, flow cytometry, and a cytometric bead array. IRF5 protein expression in NSCLC tissues (n = 102) was detected by Western blotting. The diagnostic value of IRF5 expression was determined by a receiver-operating characteristic (ROC) curve analysis.

RESULTS

The protein levels of IRF5, IL-6, and IP-10 were significantly higher in the peripheral blood of NSCLC patients than in that of healthy controls. IP-10 levels in plasma and IL-10 mRNA expression in white blood cells (WBCs) were significantly upregulated in early-stage NSCLC, whereas plasma IL-6 and IL-10 were elevated in the progressive stage. IRF5 protein levels in WBCs were positively correlated with plasma IP-10 but negatively correlated with plasma IL-10. Furthermore, the mRNA and protein levels of IRF5 in WBCs were significantly elevated in patients with early stage NSCLC compared to those in the progressive stage. Additionally, IRF5 protein levels were significantly lower in NSCLC tumour tissues than those in normal lung tissues.

CONCLUSIONS

IRF5 levels in WBCs can be significantly upregulated in early stage NSCLC and were shown to have diagnostic value as an early warning biomarker of NSCLC development.

An oligodeoxynucleotide with AAAG repeats significantly attenuates burn-induced systemic inflammatory responses via inhibiting interferon regulatory factor 5 pathway

Previously, we showed that an oligodeoxynucleotide with AAAG repeats (AAAG ODN) rescued mice from fatal acute lung injury (ALI) induced by influenza virus and inhibited production of tumor necrosis factor-α (TNF-α) in the injured lungs. However, the underlying mechanisms remain to be elucidated. Upon the bioinformatic analysis revealing that the AAAG ODN is consensus to interferon regulatory factor 5 (IRF5) binding site in the cis-regulatory elements of proinflammatory cytokines, we tried to explore whether the AAAG ODN could attenuate burn injury induced systemic inflammatory responses via inhibiting IRF5 pathway. Using the mouse model with sterile systemic inflammation induced by burn injury, we found that AAAG ODN prolonged the life span of the mice, decreased the expression of IRF5 at injured skin, reduced the production of TNF-α and IL-6 in blood and injured skin, and attenuated the ALI. Furthermore, AAAG ODN could bind IRF5 and inhibit the nuclear translocation of IRF5 in THP-1 cells. The data suggested that the AAAG ODN could act as a cytoplasmic decoy capable of interfering the function of IRF5, and be developed as a drug candidate for the treatment of inflammatory diseases.

IRF5 regulates lung macrophages M2 polarization during severe acute pancreatitis in vitro

AIM

To investigate the role of interferon regulatory factor 5 (IRF5) in reversing polarization of lung macrophages during severe acute pancreatitis (SAP) in vitro.

METHODS

A mouse SAP model was established by intraperitoneal (ip) injections of 20 μg/kg body weight caerulein. Pathological changes in the lung were observed by hematoxylin and eosin staining. Lung macrophages were isolated from bronchoalveolar lavage fluid. The quantity and purity of lung macrophages were detected by fluorescence-activated cell sorting and evaluated by real-time polymerase chain reaction (RT-PCR). They were treated with IL-4/IRF5 specific siRNA (IRF5 siRNA) to reverse their polarization and were evaluated by detecting markers expression of M1/M2 using RT-PCR.

RESULTS

SAP associated acute lung injury (ALI) was induced successfully by ip injections of caerulein, which was confirmed by histopathology. Lung macrophages expressed high levels of IRF5 as M1 phenotype during the early acute pancreatitis stages. Reduction of IRF5 expression by IRF5 siRNA reversed the action of macrophages from M1 to M2 phenotype in vitro. The expressions of M1 markers, including IRF5 (S + IRF5 siRNA vs S + PBS, 0.013 ± 0.01 vs 0.054 ± 0.047, P < 0.01), TNF-α (S + IRF5 siRNA vs S + PBS, 0.0003 ± 0.0002 vs 0.019 ± 0.018, P < 0.001), iNOS (S + IRF5 siRNA vs S + PBS, 0.0003 ± 0.0002 vs 0.026 ± 0.018, P < 0.001) and IL-12 (S + IRF5 siRNA vs S + PBS, 0.000005 ± 0.00004 vs 0.024 ± 0.016, P < 0.001), were decreased. In contrast, the expressions of M2 markers, including IL-10 (S + IRF5 siRNA vs S + PBS, 0.060 ± 0.055 vs 0.0230 ± 0.018, P < 0.01) and Arg-1 (S + IRF5 siRNA vs S + PBS, 0.910 ± 0.788 vs 0.0036 ± 0.0025, P < 0.001), were increased. IRF5 siRNA could reverse the lung macrophage polarization more effectively than IL-4.

CONCLUSION

Treatment with IRF5 siRNA can reverse the pancreatitis-induced activation of lung macrophages from M1 phenotype to M2 phenotype in SAP associated with ALI.

Genomic characterization of interferon regulatory factor 5 from rock bream (Oplegnathus fasciatus) and its role in antiviral defense

The interferon regulatory factor 5 (IRF5) is a key mediator of the Toll-like receptor (TLR)7 and TLR8 signaling pathways. In this study, we describe the identification of IRF5 (Rb-IRF5) from rock bream fish (Oplegnathus fasciatus) and its characteristics features at the genomic and expression levels. The full-length Rb-IRF5 sequence was identified from a cDNA library and its genomic sequence was obtained by screening and sequencing of a bacterial artificial chromosome (BAC) genomic DNA library of rock bream. The genomic sequence is comprised of 8 exons interrupted by 7 introns. The complete coding sequence of Rb-IRF5 is 1497 bp in length and encodes for 498 amino acids. The putative Rb-IRF5 protein consists of 3 important conserved domains: a DNA-binding domain (DBD) at the N-terminus, an IRF-associated domain (IAD), and a virus-activated domain (VAD) at the C-terminus. Based on pairwise sequence analysis, the highest sequence similarity/identity for Rb-IRF5 was observed with the IRF5 gene from turbot fish (>87%) and Japanese flounder (83%). Several important putative transcription factor-binding sites shared by the IRF gene family, including the NF-κB, Ap-1, IRF-1, and ICSBP/ISRE sites, were found in the 5' flanking region of Rb-IRF5. The predicted tertiary structure of the dimerized IAD and VAD of the Rb-IRF5 protein resembled that of its orthologs from humans. In healthy rock bream, the highest constitutive expression of Rb-IRF5 was detected in the liver. After iridovirus and polyinosinic-polycytidylic acid (poly(I:C)) challenge, Rb-IRF5 expression was significantly induced in the head kidney. Furthermore, rock bream recombinant type I interferon (Rb-IFN1) was also found to be an efficient inducer of Rb-IRF5 in a head kidney primary cell culture model. Upon IRF5 transfection, rock bream Mx (Rb-Mx), interferon I (Rb-IFN1) and tumor-necrosis factor α (Rb-TNFα) genes get significantly upregulated in rock bream heart cells. The findings of the present study explain the involvement of Rb-IRF5 in the induction of interferons and pro-inflammatory cytokines and thereby provide a model for how IRF5 modulates immune responses against viral infections in rock bream.

The influence of non-HLA gene polymorphisms and interactions on disease risk in a Western Australian multiple sclerosis cohort

Non-Human Leukocyte Antigen (HLA) genes have concomitant, although modest, effects on multiple sclerosis (MS) susceptibility; however findings have varied in different populations. Here we present the results of an association study of 16 single nucleotide polymorphisms (SNPs) in 10 non-HLA genes (IL7R, IL2RA, CLEC-16A, TYK2, CD58, IRF5, STAT3, CTLA-4, APOE, ICAM-1) in a Western Australian cohort of 350 MS patients and 498 population control subjects. Our results indicate that in this population, SNPs in IL7R, TYK2, IRF5 and APOE have modifying effects on MS susceptibility. We also found evidence of interactive protective effects between polymorphisms in the IL7R/CD58, CLEC-16A/CTLA-4, and TYK2/IRF5 genes, which in some instances are restricted within HLA- or gender-defined groups.