Association between genetic polymorphisms in interferon regulatory factor 5 (IRF5) gene and Malaysian patients with Crohn's disease

A Systematic Review on the Increasing Incidence of Inflammatory Bowel Disease in Southeast Asia: Looking Beyond the Urbanization Phenomenon

The incidence of inflammatory bowel disease (IBD) has been increasing in Southeast Asia (SEA) in tandem with its economic growth and urbanization over the past 2 decades. Specific characteristics of IBD in SEA are similar to East Asia and the West, such as the declining ratio of ulcerative colitis to Crohn's disease. However, exceptionally low familial aggregation is seen. Smoking is also not a common risk factor in patients with Crohn's disease. The incidence of perianal disease is higher in SEA than in Australia and is comparable to the West. In a multiracial population, such as Singapore and Malaysia, Indians have the highest incidence and prevalence rates, which are likely to be due to important putative mutations. For instance, a higher frequency of the NOD2 predisposing mutation SNP5 and IBD risk allele IGR2198a and IGR2092a were found in Indians. Although differences in the genetic constitution play an important role in the epidemiology and prognosis of IBD in SEA, the emergence of this disease offers a unique opportunity to identify potential exposomes that contribute to its pathogenesis.

The first association study of Protein Tyrosine Phosphatase, Non-Receptor Type 2 (PTPN2) gene polymorphisms in Malaysian patients with Crohn's disease

Crohn's disease (CD) is one of the sub-entities of Inflammatory Bowel Disease which causes chronic inflammation in the gastrointestinal tract. The development of CD has shown to have a strong genetic association. Therefore, the present study aimed to investigate the association between genetic polymorphisms in a susceptible locus of CD, the protein tyrosine phosphatase, non-receptor type 2 (PTPN2) gene and the development of CD in Malaysian patients. A total of 137 CD patients and 274 matched healthy controls were recruited in the present study. Genomic DNA was extracted from the venous blood of participants and five targeted single nucleotide polymorphisms (SNPs) in the PTPN2 gene were genotyped using polymerase chain reaction. Associations between the SNPs and CD were determined using Fisher's exact test and odds ratio. Findings showed that all five selected SNPs were not significantly associated with the development of CD in Malaysian patients, which was in contrast to studies among the European populations. Malaysian Chinese with rs487273 heterozygous G/T genotype was found to have a lower occurrence of CD (P-value = 0.0253; OR = 0.4396). Patients with rs2542152 homozygous T genotype were associated with stricturing behaviour (P-value = 0.0302, OR = 2.9944). The rs16939895 A/G genotype was associated with inflammation at the ileum site (P-value = 0.0387, OR = 2.2105)while homozygous G genotype was associated with colonic CD (P-value = 0.0164, OR = 2.3917). Functional studies of these SNPs are needed to evaluate their potential use as a biomarker for disease phenotypes among Asian patients.

The Gut Microbiome in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS)

Myalgic encephalomyelitis (ME) or Chronic Fatigue Syndrome (CFS) is a neglected, debilitating multi-systemic disease without diagnostic marker or therapy. Despite evidence for neurological, immunological, infectious, muscular and endocrine pathophysiological abnormalities, the etiology and a clear pathophysiology remains unclear. The gut microbiome gained much attention in the last decade with manifold implications in health and disease. Here we review the current state of knowledge on the interplay between ME/CFS and the microbiome, to identify potential diagnostic or interventional approaches, and propose areas where further research is needed. We iteratively selected and elaborated on key theories about a correlation between microbiome state and ME/CFS pathology, developing further hypotheses. Based on the literature we hypothesize that antibiotic use throughout life favours an intestinal microbiota composition which might be a risk factor for ME/CFS. Main proposed pathomechanisms include gut dysbiosis, altered gut-brain axis activity, increased gut permeability with concomitant bacterial translocation and reduced levels of short-chain-fatty acids, D-lactic acidosis, an abnormal tryptophan metabolism and low activity of the kynurenine pathway. We review options for microbiome manipulation in ME/CFS patients including probiotic and dietary interventions as well as fecal microbiota transplantations. Beyond increasing gut permeability and bacterial translocation, specific dysbiosis may modify fermentation products, affecting peripheral mitochondria. Considering the gut-brain axis we strongly suspect that the microbiome may contribute to neurocognitive impairments of ME/CFS patients. Further larger studies are needed, above all to clarify whether D-lactic acidosis and early-life antibiotic use may be part of ME/CFS etiology and what role changes in the tryptophan metabolism might play. An association between the gut microbiome and the disease ME/CFS is plausible. As causality remains unclear, we recommend longitudinal studies. Activity levels, bedridden hours and disease progression should be compared to antibiotic exposure, drug intakes and alterations in the composition of the microbiota. The therapeutic potential of fecal microbiota transfer and of targeted dietary interventions should be systematically evaluated.

Genetic variants involved in innate immunity modulate the risk of inflammatory bowel diseases in an understudied Malaysian population

BACKGROUND AND AIM

Inflammatory bowel diseases (IBD) are chronic gastrointestinal inflammatory conditions comprising two major subtypes: Crohn's disease (CD) and ulcerative colitis (UC). The incidence of IBD is increasing in Asian countries including Malaysia. The aim of this study was to determine whether 32 single nucleotide polymorphisms (SNPs) strongly associated with IBD from genome-wide association studies, performed mainly in Caucasian populations, are associated with IBD in a Malaysian population, correlating these findings with local and systemic inflammation.

METHODS

Selected SNPs were investigated in a Malaysian cohort comprising 36 IBD patients and 75 controls using customized matrix-assisted laser desorption ionization time-of-flight genotyping. Local mRNA and/or systemic protein levels of IL-10, IL-12, IL-22, IL-23, and TNF-α were measured in these same subjects.

RESULTS

ATG16L2 rs11235667 and LINC00824 rs6651252 was significantly associated with increased CD risk while IL12B rs56167332 was a significant protective factor. Three SNPs (SBNO2 rs2024092, CARD9 rs10781499, and rs17085007 between GPR12-USP12) were significantly associated with increased UC risk while NKX2-3 rs4409764 was a significant protective factor. After adjusting for age, gender, and ethnicity, SBNO2 rs2024092, ATG16L2 rs11235667, CARD9 rs10781499, and LINC00824 rs6651252 remained associated with IBD. Interestingly, the risk alleles of IL10 rs3024505, CARD9 rs1078149, and IL12 rs6556412 were associated with higher levels of IL-10, IL-22, and IL-23 in these same subjects, respectively.

CONCLUSIONS

This study identified eight SNPs associated with IBD and/or its subtypes in the Malaysia population, significantly advancing our understanding of the genetic contribution to IBD in this understudied population. Three of these SNPs modulated relevant cytokine levels and thus, may directly contribute to IBD pathogenesis.

The risk of rheumatoid arthritis among patients with inflammatory bowel disease: a systematic review and meta-analysis

Background

Studies have suggested that patients with inflammatory bowel disease (IBD) have an increased risk of rheumatoid arthritis (RA). However, the available data on this association are inconsistent. This meta-analysis aimed to determine the association between IBD and the risk of RA.

Methods

Observational studies investigating the RA risk among patients with IBD (Crohn disease (CD) and/or ulcerative colitis (UC)) were searched in PubMed, Embase, and Web of Science from the date of inception to December 2019. The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Relative risks (RRs) and corresponding 95% confidential intervals (CIs) were pooled with a random-effects model. Heterogeneity was evaluated using I² statistics while publication bias was determined using Begg’s and Egger’s tests. Subgroup and sensitivity analyses were performed.

Results

A total of three cohort studies, three cross-sectional studies, and two case-control studies were included in the meta-analyses. Compared to the non-IBD control or general population, there was a significantly higher risk of RA among patients with IBD (RR = 2.59; 95% CI: 1.93–3.48). Moreover, both CD (RR = 3.14; 95% CI: 2.46–4.01) and UC (RR = 2.29; 95% CI: 1.76–2.97) were associated with a significantly increased risk of RA. However, heterogeneity was substantial across studies and the subgroup analyses failed to identify the potential source of heterogeneity.

Conclusions

Patients with IBD have a greater risk of developing RA. Rheumatologists should be consulted when patients with IBD present with undifferentiated joint complaints. However, more prospective cohort studies are needed to validate these results.

Autoimmunity-Related Risk Variants in PTPN22 and CTLA4 Are Associated With ME/CFS With Infectious Onset

Single nucleotide polymorphisms (SNP) in various genes have been described to be associated with susceptibility to autoimmune disease. In this study, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients and controls were genotyped for five immune gene SNPs in tyrosine phosphatase non-receptor type 22 (PTPN22, rs2476601), cytotoxic T-lymphocyte-associated protein 4 (CTLA4, rs3087243), tumor necrosis factor (TNF, rs1800629 and rs1799724), and interferon regulatory factor 5 (IRF5, rs3807306), which are among the most important risk variants for autoimmune diseases. Analysis of 305 ME/CFS patients and 201 healthy controls showed significant associations of the PTPN22 rs2476601 and CTLA4 rs3087243 autoimmunity-risk alleles with ME/CFS. The associations were only found in ME/CFS patients, who reported an acute onset of disease with an infection (PTPN22 rs2476601: OR 1.63, CI 1.04–2.55, p = 0.016; CTLA4 rs3087243: OR 1.53, CI 1.17–2.03, p = 0.001), but not in ME/CFS patients without infection-triggered onset (PTPN22 rs2476601: OR 1.09, CI 0.56–2.14, p = 0.398; CTLA4 rs3087243: OR 0.89, CI 0.61–1.30, p = 0.268). This finding provides evidence that autoimmunity might play a role in ME/CFS with an infection-triggered onset. Both genes play a key role in regulating B and T cell activation.

Genetic polymorphisms of ATG16L1 and IRGM genes in Malaysian patients with Crohn's disease

OBJECTIVE

To investigate the association between genetic polymorphisms in ATG16L1 and IRGM genes and the development of Crohn's disease (CD) in Malaysian patients.

METHODS

Altogether 335 participants were recruited, including 85 patients with CD and 250 unrelated healthy controls, and their informed consent was obtained. Genomic DNA was extracted via a conventional phenol-chloroform extraction method. Six single nucleotide polymorphisms (SNPs) in ATG16L1 and IRGM genes were genotyped using TaqMan SNP genotyping assays. Associations between SNP and CD were determined using Fisher's exact test, odds ratio, and 95% confidence interval. Statistical power and the Hardy-Weinberg equilibrium were also calculated.

RESULTS

Two SNPs (rs2241880 and rs6754677) in the ATG16L1 gene were significantly associated with the onset of CD in the Malaysian population. The A allele and homozygous A/A genotype of the rs2241880 A/G polymorphism were protective against CD in the overall Malaysian and Malay population. The G allele and homozygous G/G genotype of the rs6754677 G/A polymorphism were protective in the Indian population, whereas the homozygous A/A genotype showed a risk of developing CD. The homozygous G/G genotype of IRGM rs11747270 was significantly present in the controls. However, this significance was not observed in a race-stratified analysis. All three ATG16L1 SNPs were associated with inflamed terminal ileum. IRGM rs4958847 and rs11747270 increased the risk of developing arthritis in patients with CD.

CONCLUSION

We found a significant association between SNP, which are located in autophagy-related genes, and CD in a Malaysian population.

IRF5 is elevated in childhood-onset SLE and regulated by histone acetyltransferase and histone deacetylase inhibitors

Interferon regulatory factor 5 (IRF5) plays a critical role in the induction of type I interferon, proinflammatory cytokines and chemokines, and participates in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE). However, the relationship between IRF5 and childhood-onset SLE remains elusive. In the present study, we demonstrated that levels of mRNA expression of IRF5, IFN-α, and Sp1 were significantly increased in childhood-onset SLE, as seen on quantitative real-time PCR, and the expression of Sp1 and IFN-α was positively correlated with IRF5. In addition to being used as antitumor drugs, a number of histone deacetylase inhibitors (HDACi) display potent anti-inflammatory properties; however, their effects on IRF5 expression remain unclear. In this study, we identified that HDACi trichostatin A (TSA) and histone acetyltransferase (HAT)-p300 downregulated IRF5 promoter activity, mRNA expression, and protein level, whereas the HAT-p300/CBP-associated factor had no effect. Moreover, TSA inhibited the production of TNF-α and IL-6 in differentiated THP-1cells. Furthermore, chromatin immunoprecipitation assays revealed that TSA inhibited DNA binding of Sp1, RNA polymerase II, HDAC3, and p300 to the core promoter region of IRF5. Our results suggest that HDACi may have therapeutic potential in patients with autoimmune diseases such as SLE through repression of IRF5 expression.

Interferon regulatory factor 5 gene polymorphism in Egyptian children with systemic lupus erythematosus

Background

Increased expression of interferon-inducible genes is implicated in the pathogenesis of systemic lupus erythematosus (SLE). Interferon regulatory factor 5 (IRF5) is one of the transcription factors regulating interferon and was proved to be implicated in the pathogenesis of SLE in different populations.

Objectives

The objective of this study was to investigate the correlation between polymorphisms of the IRF5 gene and SLE susceptibility in a cohort of Egyptian children and to investigate their association with clinico-pathological features, especially lupus nephritis.

Subjects and methods

Typing of interferon regulatory factor 5 rs10954213, rs2004640 and rs2280714 polymorphisms were done using polymerase chain reaction-restriction fragment length polymorphism for 100 children with SLE and 100 matched healthy controls.

Results

Children with SLE had more frequent T allele and TT genotype of rs2004640 ( Pc = 0.003 and 0.024, respectively) compared to controls. Patients with nephritis had more frequent T allele of rs2004640 compared to controls ( Pc = 0.003). However the allele and genotype frequencies of the three studied polymorphisms did not show any difference in patients with nephritis in comparison to those without nephritis. Haplotype GTA of rs10954213, rs2004640 and rs2280714, respectively, was more frequent in lupus patients in comparison to controls ( p = 0.01) while the haplotype GGG was more frequent in controls than lupus patients ( p = 0.011).

Conclusion

The rs2004640 T allele and TT genotype and GTA haplotype of rs rs10954213, rs2004640, and rs2280714, respectively, can be considered as risk factors for the development of SLE. The presence of the rs2004640 T allele increases the risk of nephritis development in Egyptian children with SLE.

Mangiferin inhibits macrophage classical activation via downregulating interferon regulatory factor 5 expression

Mangiferin is a natural polyphenol and the predominant effective component of Mangifera indica Linn. leaves. For hundreds of years, Mangifera indica Linn. leaf has been used as an ingredient in numerous traditional Chinese medicine preparations for the treatment of bronchitis. However, the pharmacological mechanism of mangiferin in the treatment of bronchitis remains to be elucidated. Macrophage classical activation is important role in the process of bronchial airway inflammation, and interferon regulatory factor 5 (IRF5) has been identified as a key regulatory factor for macrophage classical activation. The present study used the THP-1 human monocyte cell line to investigate whether mangiferin inhibits macrophage classical activation via suppressing IRF5 expression in vitro. THP-1 cells were differentiated to macrophages by phorbol 12-myristate 13-acetate. Macrophages were polarized to M1 macrophages following stimulation with lipopolysaccharide (LPS)/interferon-γ (IFN-γ). Flow cytometric analysis was conducted to detect the M1 macrophages. Reverse transcription-quantitative polymerase chain reaction was used to investigate cellular IRF5 gene expression. Levels of proinflammatory cytokines and IRF5 were assessed following cell culture and cellular homogenization using enzyme-linked immunosorbent assay. IRF5 protein and nuclei co-localization was performed in macrophages with laser scanning confocal microscope immunofluorescence analysis. The results of the present study demonstrated that mangiferin significantly inhibits LPS/IFN-γ stimulation-induced classical activation of macrophages in vitro and markedly decreases proinflammatory cytokine release. In addition, cellular IRF5 expression was markedly downregulated. These results suggest that the inhibitory effect of mangiferin on classical activation of macrophages may be exerted via downregulation of cellular IRF5 expression levels.

Association of NOD1, CXCL16, STAT6 and TLR4 gene polymorphisms with Malaysian patients with Crohn's disease

Crohn's disease (CD) is a prominent type of inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract. CD is known to have higher prevalence in the Western countries, but the number of cases has been increasing in the past decades in Asia, including Malaysia. Therefore, there is a need to investigate the underlining causes of CD that may shed light on its prevention and treatment. In this study, genetic polymorphisms in NOD1 (rs2075820), CXCL16 (rs2277680), STAT6 (rs324015) and TLR4 (rs4986791) genes were examined in a total of 335 individuals (85 CD patients and 250 healthy controls) with PCR-RFLP approach. There was no significant association observed between NOD1 rs2075820 and STAT6 rs324015 with the onset of CD in the studied cohort. However, the G allele of CXCL16 rs2277680 was found to have a weak association with CD patients (P = 0.0482; OR = 1.4310). The TLR4 rs4986791 was also significantly associated to CD. Both the homozygous C genotype (P = 0.0029; OR = 0.3611) and C allele (P = 0.0069; OR = 0.4369) were observed to confer protection against CD. On the other hand, the heterozygous C/T genotype was a risk genotype (P = 0.0015; OR = 3.1392). Further ethnic-stratified analysis showed that the significant associations in CXCL16 rs2277680 and TLR4 rs4986791 were accounted by the Malay cohort. In conclusion, the present study reported two CD-predisposing loci in the Malay CD patients. However, these loci were not associated to the onset of CD in Chinese and Indian patients.

Interferon regulatory factor 5 in human autoimmunity and murine models of autoimmune disease

Interferon regulatory factor 5 (IRF5) has been demonstrated as a key transcription factor of the immune system, playing important roles in modulating inflammatory immune responses in numerous cell types including dendritic cells, macrophages, and B cells. As well as driving the expression of type I interferon in antiviral responses, IRF5 is also crucial for driving macrophages toward a proinflammatory phenotype by regulating cytokine and chemokine expression and modulating B-cell maturity and antibody production. This review highlights the functional importance of IRF5 in a disease setting, by discussing polymorphic mutations at the human Irf5 locus that lead to susceptibility to systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. In concordance with this, we also discuss lessons in IRF5 functionality learned from murine in vivo models of autoimmune disease and inflammation and hypothesize that modulation of IRF5 activity and expression could provide potential therapeutic benefits in the clinic.