Gender-specific influence of the chromosome 16 chemokine gene cluster on the susceptibility to Multiple Sclerosis

Chemokines in Prediabetes and Type 2 Diabetes: A Meta-Analysis

Background

A growing number of studies found inconsistent results on the role of chemokines in the progression of type 2 diabetes (T2DM) and prediabetes (PDM). The purpose of this meta-analysis was to summarize the results of previous studies on the association between the chemokines system and T2DM/PDM.

Methods

We searched in the databases, PubMed, Web of Science, Embase and Cochrane Library, for eligible studies published not later than March 1, 2020. Data extraction was performed independently by 2 reviewers, on a standardized, prepiloted form. Group differences in chemokines concentrations were summarized using the standardized mean difference (SMD) with a 95% confidence interval (CI), calculated by performing a meta-analysis using the random-effects model.

Results

We identified 98 relevant studies that investigated the association between 32 different chemokines and T2DM/PDM. Altogether, these studies involved 14,708 patients and 14,574 controls. Results showed that the concentrations of CCL1, CCL2, CCL4, CCL5, CCL11, CXCL8, CXCL10 and CX3CL1 in the T2DM patients were significantly higher than that in the controls, while no difference in these concentrations was found between the PDM patients and controls.

Conclusion

Progression of T2DM may be associated with elevated concentrations of chemokines.

Meta-Analysis Registration

PROSPERO, identifier CRD42019148305.

The role of chemokines and chemokine receptors in multiple sclerosis

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Summarize the study of the role of chemokines and their receptors in multiple sclerosis (MS) patients and MS animal models.

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Discuss their potential significance in inflammatory injury and repair of MS.

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Summarize the progress in the research of MS antagonists in recent years with chemokine receptors as targets.

Multiple sclerosis (MS) is a chronic inflammatory disease that is characterized by leukocyte infiltration and subsequent axonal damage, demyelinating inflammation, and formation of sclerosing plaques in brain tissue. The results of various studies in patients indicate that autoimmunity and inflammation make an important impact on the pathogenesis of MS. Chemokines are key mediators of inflammation development and cell migration, mediating various immune cell responses, including chemotaxis and immune activation, and are important in immunity and inflammation, therefore we focus on chemokines and their receptors in multiple sclerosis. In this article, we summarize the study of the role of prominent chemokines and their receptors in MS patients and MS animal modelsand discuss their potential significance in inflammatory injury and repair of MS. We have also summarized the progress in the treatment of multiple sclerosis antagonists in recent years with chemokine receptors as targets.

Chemokine gene polymorphisms association with increased risk of type 2 diabetes mellitus in Tatar ethnic group, Russia

Recent studies have shown that chemokines play an important role in the development of chronic inflammation in adipose tissue, obesity pathogenesis, glucose intolerance and type 2 diabetes. It has also been revealed that some SNPs in chemokine genes are associated with obesity, insulin resistance, type 2 diabetes and diabetes complications in different ethnic groups. The aim of this study was to determine the associations between SNPs in chemokine genes and type 2 diabetes in participants of Tatar ethnic group, living in Bashkortostan. Case-control and cross-sectional study were included in our study design. Five SNPs were genotyped in 440 type 2 diabetes (160 men and 280 women), 58.8 ± 9.2 years old (mean ± SD), BMI 29.3 ± 3.9 kg/m² (mean ± SD) patients of Tatar ethnicity, and a control group of 500 Tatars (180 men and 320 women), 55.2 ± 11.6 years old (mean ± SD), BMI 25.9 ± 4.3 kg/m² (mean ± SD). The SNPs rs6749704 in CCL20 [odds ratio (OR) = 2.77 (95% CI 1.81-4.25), р = 0.0001], rs2107538 in CCL5 [odds ratio (OR) = 1.80 (95% CI 1.46-2.22), p = 0.0001] were significantly associated with type 2 diabetes. Regression analysis revealed that rs1696941 in CCL11 was associated with the onset age and duration of type 2 diabetes as well as with HbA_1c level (p = 0.034, p = 0.036 and p = 0.0054, respectively). The SNPs rs223828 in CCL17 and rs6749704 in CCL20 were correlated with obesity as estimated by BMI (p = 0.0004, p = 0.029, respectively). Rs223828 in CCL17 revealed the association with postprandial glucose level (p = 0.024) and HbA_1c (p = 0.008). These data demonstrate that variants of chemokine genes are associated with type 2 diabetes and obesity of Tatar ethnic group inhabiting Bashkortostan Republic. Novel associations of the polymorphic loci in CCL20 (rs6749704) and CCL5 (rs2107538) genes with type 2 diabetes had been identified as a result of the conducted research.

Association of the polymorphisms in Th2 chemotaxis-related genes with the development and prognosis of autoimmune thyroid diseases

The prognosis of autoimmune thyroid disease (AITD) is difficult to predict. Th2 cells suppress the differentiation of Th1 and Th17 cells, which are associated with the prognosis of AITD. However, there are few reports as to whether Th2 chemotaxis-related genes, such as CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells), IL-25, TARC/CCL17 (Thymus and activation regulated chemokine/chemokine ligand 17) or STAT6 (Signal transducer and activator of transcription 6), affect the pathology of and/or susceptibility to AITD. Therefore, in this study, we genotyped functional SNPs in these genes to clarify the association of the genetic differences of genes related to Th2 differentiation and chemotaxis with the development and the prognosis of AITDs. The frequencies of the AA genotype of the CRTH2 rs545659 SNP and the CC genotype and the C allele of the CRTH2 rs634681 SNP were higher in patients with severe HD than in patients with mild HD. The frequency of the CC genotype in the TARC rs223828 SNP was higher in patients with intractable GD than in patients with GD in remission. In conclusion, the CRTH2 rs545659 and rs634681 SNPs were associated with the severity of HD, and the TARC/CCL17 rs223828 SNP was associated with the intractability of GD.

CXCL13 polymorphism is associated with essential hypertension in Tatars from Russia

Essential arterial hypertension is a disease with distinct yet unexplored inflammatory component. Our aim was to assess the role of chemokine genes and their interaction in its development. Genotyping of polymorphic markers in six chemokine genes (CXCL13, CCL8, CCL16, CCL17, CCL18, and CCL23) was performed in the group of 522 men of Tatar ethnic origin from the Republic of Bashkortostan, Russia (213 patients with essential hypertension and 309 healthy individuals without history of cardiovascular disease). We found a strong association of CXCL13 rs355689*C allele with essential hypertension under additive (OR 0.56, P_FDR = 0.008) and dominant (OR 0.41, P_FDR 4.38 × 10^- 4) genetic model. The analysis of gene-gene interactions revealed 12 allele/genotype combinations that remained significantly associated with essential hypertension after correction for multiple testing was applied, and each of these combinations included CXCL13 rs355689 polymorphism. Our results indicate that CXCL13 rs355689 polymorphism is strongly associated with essential hypertension in the ethnic group of Tatars, alone and in combination with polymorphic markers in other chemokine genes.

Chemokine CCL17 is expressed by dendritic cells in the CNS during experimental autoimmune encephalomyelitis and promotes pathogenesis of disease

The CC chemokine ligand 17 (CCL17) and its cognate CC chemokine receptor 4 (CCR4) are known to control leukocyte migration, maintenance of T_H17 cells, and regulatory T cell (T_reg) expansion in vivo. In this study we characterized the expression and functional role of CCL17 in the pathogenesis of experimental autoimmune encephalomyelitis (EAE). Using a CCL17/EGFP reporter mouse model, we could show that CCL17 expression in the CNS can be found in a subset of classical dendritic cells (DCs) that immigrate into the CNS during the effector phase of MOG-induced EAE. CCL17 deficient (CCL17^-/-) mice exhibited an ameliorated disease course upon MOG-immunization, associated with reduced immigration of IL-17 producing CD4⁺ T cells and peripheral DCs into the CNS. CCL17^-/- DCs further showed equivalent MHC class II and costimulatory molecule expression and an equivalent capacity to secrete IL-23 and induce myelin-reactive T_H17 cells when compared to wildtype DCs. In contrast, their transmigration in an in vitro model of the blood-brain barrier was markedly impaired. In addition, peripheral T_reg cells were enhanced in CCL17^-/- mice at peak of disease pointing towards an immunoregulatory function of CCL17 in EAE. Our study identifies CCL17 as a unique modulator of EAE pathogenesis regulating DC trafficking as well as peripheral T_reg cell expansion in EAE. Thus, CCL17 operates at distinct levels and on different cell subsets during immune response in EAE, a property harboring therapeutic potential for the treatment of CNS autoimmunity.

Regulatory T cells in multiple sclerosis and myasthenia gravis

Multiple sclerosis (MS) is a chronic debilitating disease of the central nervous system primarily mediated by T lymphocytes with specificity to neuronal antigens in genetically susceptible individuals. On the other hand, myasthenia gravis (MG) primarily involves destruction of the neuromuscular junction by antibodies specific to the acetylcholine receptor. Both autoimmune diseases are thought to result from loss of self-tolerance, which allows for the development and function of autoreactive lymphocytes. Although the mechanisms underlying compromised self-tolerance in these and other autoimmune diseases have not been fully elucidated, one possibility is numerical, functional, and/or migratory deficits in T regulatory cells (Tregs). Tregs are thought to play a critical role in the maintenance of peripheral immune tolerance. It is believed that Tregs function by suppressing the effector CD4+ T cell subsets that mediate autoimmune responses. Dysregulation of suppressive and migratory markers on Tregs have been linked to the pathogenesis of both MS and MG. For example, genetic abnormalities have been found in Treg suppressive markers CTLA-4 and CD25, while others have shown a decreased expression of FoxP3 and IL-10. Furthermore, elevated levels of pro-inflammatory cytokines such as IL-6, IL-17, and IFN-γ secreted by T effectors have been noted in MS and MG patients. This review provides several strategies of treatment which have been shown to be effective or are proposed as potential therapies to restore the function of various Treg subsets including Tr1, iTr35, nTregs, and iTregs. Strategies focusing on enhancing the Treg function find importance in cytokines TGF-β, IDO, interleukins 10, 27, and 35, and ligands Jagged-1 and OX40L. Likewise, strategies which affect Treg migration involve chemokines CCL17 and CXCL11. In pre-clinical animal models of experimental autoimmune encephalomyelitis (EAE) and experimental autoimmune myasthenia gravis (EAMG), several strategies have been shown to ameliorate the disease and thus appear promising for treating patients with MS or MG.

The Association of Chemokine Gene Polymorphisms with VKH and Behcet's Disease in a Chinese Han Population

To investigate the association of chemokine gene polymorphisms and Behcet's disease (BD) and Vogt Koyanagi Harada (VKH) disease in a Chinese Han population. A case-control study was performed. Three hundred and seventy-one BD patients, 371 VKH disease patients, and 605 healthy controls were recruited to determine genetic variants of 26 SNPs in 12 chemokine genes with iPLEX Gold genotyping assay and Sequenom MassARRAY or TaqMan SNP assays. In this study, P_uncorr values showed a weak association of five SNPs of five genes in BD and three SNPs of three genes in VKH disease. However, after Bonferroni correction, the 26 investigated SNPs showed no significant differences in genetic variants, including genotype and allele frequencies, between BD or VKH disease patients and healthy individuals. Haplotype analysis for the chemokine genes showed a significant association with the TC haplotype of CXCL12 in VKH. Stratified gender analysis and genotype-phenotype analysis were conducted to analyze the association of the 26 SNPs of 12 chemokine genes with BD and VKH disease. However, no significant association was observed after Bonferroni correction. This study showed no association of 26 SNPs in 12 chemokine genes with both BD and VKH disease in a Chinese Han population.

Regulatory polymorphisms modulate the expression of HLA class II molecules and promote autoimmunity

Targeted sequencing of sixteen SLE risk loci among 1349 Caucasian cases and controls produced a comprehensive dataset of the variations causing susceptibility to systemic lupus erythematosus (SLE). Two independent disease association signals in the HLA-D region identified two regulatory regions containing 3562 polymorphisms that modified thirty-seven transcription factor binding sites. These extensive functional variations are a new and potent facet of HLA polymorphism. Variations modifying the consensus binding motifs of IRF4 and CTCF in the XL9 regulatory complex modified the transcription of HLA-DRB1, HLA-DQA1 and HLA-DQB1 in a chromosome-specific manner, resulting in a 2.5-fold increase in the surface expression of HLA-DR and DQ molecules on dendritic cells with SLE risk genotypes, which increases to over 4-fold after stimulation. Similar analyses of fifteen other SLE risk loci identified 1206 functional variants tightly linked with disease-associated SNPs and demonstrated that common disease alleles contain multiple causal variants modulating multiple immune system genes.

GWAS-identified multiple sclerosis risk loci involved in immune response: validation in Russians

Multiple sclerosis (MS) is a chronic neuro-inflammatory disease of complex etiology. The results of GWAS, a high-throughput method to discover genetic architecture of MS, require replication in independent ethnic groups. We performed a replication study of nine GWAS-identified SNPs in immune response in Russians. Associations of CLEC16A and IL2RA with MS were validated. Besides, we observed the associations of CLEC16A and IRF8 in women, and IL7RA and CD58 in men. With multi-locus association analysis two protective biallelic combinations: (TNFRSF1A*T+CLEC16A*A) and (TNFRSF1A*T+IRF8*A) were identified in women. Associations of CLEC16A*G/G and both biallelic combinations in women with MS survived the permutation test.

Elevated serum levels of macrophage-derived chemokine and thymus and activation-regulated chemokine in autistic children

Background

In some autistic children, there is an imbalance of T helper (Th)1/Th2 lymphocytes toward Th2, which may be responsible for the induction of the production of autoantibodies in these children. Th2 lymphocytes express CCR4 receptors. CCR4 ligands include macrophage-derived chemokine (MDC) and thymus and activation-regulated chemokine (TARC). They direct trafficking and recruitment of Th2 cells. We are the first to measure serum levels of CCR4 ligands in relation to the degree of the severity of autism.

Methods

Serum concentrations of MDC and TARC were measured, by quantitative sandwich enzyme immunoassay technique, in 56 autistic children and 32 healthy matched children.

Results

Autistic children had significantly higher serum levels of MDC and TARC than healthy controls (P <0.001 and P <0.001, respectively). Children with severe autism had significantly higher serum levels of MDC and TARC than patients with mild to moderate autism (P <0.001 and P = 0.01, respectively). In addition, there were significant positive correlations between CARS and serum levels of both MDC (P <0.001) and TARC (P <0.001) in children with autism. There were significant positive correlations between serum levels of MDC and TARC in autistic children (P <0.001).

Conclusions

Serum levels of CCR4 ligands were elevated in autistic children and they were significantly correlated to the degree of the severity of autism. However, further research is warranted to determine the pathogenic role of CCR4 ligands in autism and to shed light on the therapeutic role of CCR4-ligand antagonism in autistic children.

Analysis of autosomal genes reveals gene-sex interactions and higher total genetic risk in men with systemic lupus erythematosus

OBJECTIVES

Systemic lupus erythematosus (SLE) is a sexually dimorphic autoimmune disease which is more common in women, but affected men often experience a more severe disease. The genetic basis of sexual dimorphism in SLE is not clearly defined. A study was undertaken to examine sex-specific genetic effects among SLE susceptibility loci.

METHODS

A total of 18 autosomal genetic susceptibility loci for SLE were genotyped in a large set of patients with SLE and controls of European descent, consisting of 5932 female and 1495 male samples. Sex-specific genetic association analyses were performed. The sex-gene interaction was further validated using parametric and non-parametric methods. Aggregate differences in sex-specific genetic risk were examined by calculating a cumulative genetic risk score for SLE in each individual and comparing the average genetic risk between male and female patients.

RESULTS

A significantly higher cumulative genetic risk for SLE was observed in men than in women. (P=4.52x10-8) A significant sex-gene interaction was seen primarily in the human leucocyte antigen (HLA) region but also in IRF5, whereby men with SLE possess a significantly higher frequency of risk alleles than women. The genetic effect observed in KIAA1542 is specific to women with SLE and does not seem to have a role in men.

CONCLUSIONS

The data indicate that men require a higher cumulative genetic load than women to develop SLE. These observations suggest that sex bias in autoimmunity could be influenced by autosomal genetic susceptibility loci.

CCR4 contributes to the pathogenesis of experimental autoimmune encephalomyelitis by regulating inflammatory macrophage function

Chemokines and their receptors play a critical role in orchestrating the immune response during experimental autoimmune encephalomyelitis (EAE). Expression of CCR4 and its ligand CCL22 has been observed in ongoing disease. Here we describe a role for CCR4 in EAE, illustrating delayed and decreased disease incidence in CCR4(-/-) mice corresponding with diminished CNS infiltrate. Peripheral T cell responses were unaltered in CCR4(-/-) mice; rather, disease reduction was related to reduced CD11b(+)Ly6C(hi) inflammatory macrophage (iMϕ) numbers and function. These results provide evidence that CCR4 regulates EAE development and further supports the involvement of CCR4 in iMϕ effector function.

Role of gender in multiple sclerosis: clinical effects and potential molecular mechanisms

Multiple sclerosis (MS) is more prevalent in females than males, and this female predominance is increasing as time goes by. Additionally, gender appears to play critical roles in development, progression and treatment of MS, and is therefore an aspect that should always be considered in the design and interpretation of research and clinical trials for MS. In this review, factors that could potentially explain the gender-biased observations in MS are discussed. These include sex-specific differences between the male and female immune systems and nervous systems, genetic and epigenetic or environmental-related effects, the effects of gonadal hormones, and materno-fetal interactions.

Zonulin and its regulation of intestinal barrier function: the biological door to inflammation, autoimmunity, and cancer

The primary functions of the gastrointestinal tract have traditionally been perceived to be limited to the digestion and absorption of nutrients and to electrolytes and water homeostasis. A more attentive analysis of the anatomic and functional arrangement of the gastrointestinal tract, however, suggests that another extremely important function of this organ is its ability to regulate the trafficking of macromolecules between the environment and the host through a barrier mechanism. Together with the gut-associated lymphoid tissue and the neuroendocrine network, the intestinal epithelial barrier, with its intercellular tight junctions, controls the equilibrium between tolerance and immunity to non-self antigens. Zonulin is the only physiological modulator of intercellular tight junctions described so far that is involved in trafficking of macromolecules and, therefore, in tolerance/immune response balance. When the finely tuned zonulin pathway is deregulated in genetically susceptible individuals, both intestinal and extraintestinal autoimmune, inflammatory, and neoplastic disorders can occur. This new paradigm subverts traditional theories underlying the development of these diseases and suggests that these processes can be arrested if the interplay between genes and environmental triggers is prevented by reestablishing the zonulin-dependent intestinal barrier function. This review is timely given the increased interest in the role of a "leaky gut" in the pathogenesis of several pathological conditions targeting both the intestine and extraintestinal organs.

A common variant in TFB1M is associated with reduced insulin secretion and increased future risk of type 2 diabetes

Type 2 diabetes (T2D) evolves when insulin secretion fails. Insulin release from the pancreatic β cell is controlled by mitochondrial metabolism, which translates fluctuations in blood glucose into metabolic coupling signals. We identified a common variant (rs950994) in the human transcription factor B1 mitochondrial (TFB1M) gene associated with reduced insulin secretion, elevated postprandial glucose levels, and future risk of T2D. Because islet TFB1M mRNA levels were lower in carriers of the risk allele and correlated with insulin secretion, we examined mice heterozygous for Tfb1m deficiency. These mice displayed lower expression of TFB1M in islets and impaired mitochondrial function and released less insulin in response to glucose in vivo and in vitro. Reducing TFB1M mRNA and protein in clonal β cells by RNA interference impaired complexes of the mitochondrial oxidative phosphorylation system. Consequently, nutrient-stimulated ATP generation was reduced, leading to perturbed insulin secretion. We conclude that a deficiency in TFB1M and impaired mitochondrial function contribute to the pathogenesis of T2D.

Progranulin gene variability increases the risk for primary progressive multiple sclerosis in males

Progranulin (GRN) gene variability has been analyzed in a sample of 354 patients with multiple sclerosis (MS) compared with 343 controls. No significant differences were observed, but by stratifying according to MS subtypes, a significant increased frequency of the rs2879096 TT genotype was found in primary progressive MS (PPMS) patients versus controls (16.0 vs 3.5%, P=0.023, odds ratio (OR) 5.2, 95% confidence interval (CI) 1.2-21.4). In addition, in PPMS, an association with the C allele of rs4792938 was observed (55.3 vs 33.5%, P=0.011, OR 2.4, 95% CI 1.2-4.7). An independent population was studied as replication, failing to confirm results previously obtained. Stratifying according to gender, an association with rs4792938 C allele was found in male PPMS patients compared with controls (40.7 vs 26.9%, P=0.002, OR 1.87, 95% CI 1.2-2.8). An association with the rs2879096T allele was observed (29.2 in patients compared with 18.9% in controls, P=0.012, OR 1.77, 95% CI 1.1-2.8). Haplotype analysis showed that TC haplotype frequency is increased in PPMS male patients compared with male controls (25.7 vs 16.6%; P=0.02, OR 1.69, 95% CI 1.1-2.7), whereas the respective GC haplotype seems to exert a protective effect, as its frequency is decreased in patients compared with controls (55.8% vs 70.9%; P=0.001, OR 0.52, 95% CI 0.4-0.8). Therefore, GRN haplotypes likely influence the risk of developing PPMS in males.

Sex-specific therapeutic strategies based on neuroactive steroids: In search for innovative tools for neuroprotection

Different pathologies of the central and peripheral nervous system show sex differences in their incidence, symptomatology and/or neurodegenerative outcome. These include Parkinson's disease, Alzheimer's disease, Huntington's disease, multiple sclerosis, traumatic brain injury, stroke, autism, schizophrenia, depression, anxiety disorders, eating disorders and peripheral neuropathy. These sex differences reveal the need for sex-specific neuroprotective strategies. This review article and other manuscripts published in this issue of Hormones and Behavior analyze possible sex-specific therapeutic strategies based on neuroactive steroids. In particular in our introductory article, the possibility that sex differences in the levels or in the action of neuroactive steroids may represent causative factors for sex differences in the incidence or manifestation of pathologies of the nervous system is considered.

European Charcot Foundation Lecture: the natural history of multiple sclerosis and gender

The role of gender in the natural history of multiple sclerosis (MS) is multi-faceted. Earliest debate on this topic was about the sex ratio (female:male) among affected individuals. It was only clearly shown within the last 4 decades that females are more often affected. The sex ratio continues to intrigue researchers. An observed increase in the sex ratio among more recently born MS patients has now been taken as a clear indication that the rate of MS is truly increasing in many geographical areas. This temporal increase in females has been relatively rapid, implicating environmental rather than genetic risk factors. Gender issues in MS expand beyond the scope of sex ratio. Gender has an impact on various aspects of MS, including age of onset, "parent-of-origin" effects (seen in half-siblings, twin sibships, avuncular pairs, transmission of HLA haplotype), recurrence risks for relatives of MS patients and the topic of reproduction when one parent has MS. Gender issues can also confound data collection and analyses with respect to studies on comorbidity, risk factors and family history. In fact, it has now been clearly validated and quantified that among persons with MS, there is a sex-specificity of recall and reporting bias as well a greater female awareness of medical history.

Immunological mechanisms behind the cystic fibrosis-ABPA link

Allergic bronchopulmonary aspergillosis (ABPA), a pulmonary hypersensitivity disease mediated by an allergic response to Aspergillus fumigatus (A. fumigatus), occurs preferentially in disease conditions with an impaired pulmonary immunity, especially in cystic fibrosis (CF) and allergic asthma. The pathophysiological mechanisms underlying the link between CF and ABPA are poorly understood. Animal and human data support a critical role for chemokines, especially CCL17 and its receptor CCR4, in ABPA. A summary and discussion of the immunological mechanism involved in the pathogenesis of ABPA with a focus on CF lung disease and the role of chemokines is presented here.