Investigation of TNFA 308G > A and TNFB 252G > A polymorphisms in genetic susceptibility to migraine

Role of TNF-α in the Pathogenesis of Migraine

Background

Neurogenic neuroinflammation has a wide role in migraine pathogenesis including the transition from episodic migraine to chronic one. The seed molecule of neurogenic neuroinflammation, i.e., the TNF-α proinflammatory molecule, has gathered a lot of attention. This pleiotropic cytokine is a classical component of inflammatory soup, secreted by the microglial cell, and promotes a wide range of inflammatory reactions.

Aim

In this review, we aimed to provide a culminating and comprehending glimpse into the TNF-α in association with the migraine.

Method

A systematic literature survey method with a mixture of keywords was utilized to grasp the different elements that represent the association between TNF-α and migraine. Discussion. Highlighted the probable involvement of the TNF-α with migraine, the complexity of the matter such as activation of NF-KB signaling cascade, autoactivation, sensitization, and increased likelihood of transition cannot be neglected. Being TNF-α as a core node, it becomes the factor for linking diseases such as chronic inflammatory disorders, including COVID-19, and also interaction with other genes to develop severe conditions.

Conclusion

To this end, TNF-α plays a critical role in chronification, and inhibiting its signaling would likely be a crucial strategy for migraine therapy.

Comprehensive analysis of genes associated with migraine in the Indian population: a meta-analysis of genetic association studies with trial sequential analysis

Migraine is a complex disorder with multigenic inheritance and is characterized by the cardinal symptom of unilateral headache. Many genes are responsible for increasing the susceptibility of disease within different populations. Therefore, our primary aim in this review was to catalog the many genes that have been studied in India and after collecting the necessary information, we calculated a more precise risk relationship between an identified variation and migraine. The gene and its associated risk variant were discovered in the Indian population using a PRISMA-based systematic literature review guideline from online databases such as PubMed & Google Scholar. We constructed pooled odds ratios with 95% confidence intervals using multiple genetic models. Also, we looked for heterogeneity using Cochran's Q Test and the I2 statistic. Publication bias was analyzed using Begg's and Egger's tests. A p-value less than 0.05 was judged to be statistically significant for all tests. After a critical analysis, a total of 24 studies explored about 21 genes with 31 variants out of which only nine genes have been studied more than two times in the Indian population and thus were found eligible for the meta-analysis. It has been found, that the ACE-DD variant (allele model: OR: 1.37 [1.11-1.69], I2 = 0%/ fixed model), ESR1-PvuII (allele model: OR: 1.47 [1.24-1.74], I2 = 0%/ fixed model) significantly increases the risk of migraine in Indian population. Also, a protective role of the LRP1-rs11172113variant was observed for both migraine and its clinical subtype i.e., MA (allelic model: OR of 0.65 [0.50-0.83] I2 = 44% and allele: OR: 0.54 [0.37-0.78], I2 = 52%) respectively. Overall, the results of this meta-analysis indicated that the ACE-DD variant and the ESR1-PvuII were associated with an increased risk of migraine in the Indian community, while the LRP1-rs11172113 variant was associated with protection from migraine in this population.

Experimental and Clinical Investigation of Cytokines in Migraine: A Narrative Review

The role of neuroinflammation in the pathophysiology of migraines is increasingly being recognized, and cytokines, which are important endogenous substances involved in immune and inflammatory responses, have also received attention. This review examines the current literature on neuroinflammation in the pathogenesis of migraine. Elevated TNF-α, IL-1β, and IL-6 levels have been identified in non-invasive mouse models with cortical spreading depolarization (CSD). Various mouse models to induce migraine attack-like symptoms also demonstrated elevated inflammatory cytokines and findings suggesting differences between episodic and chronic migraines and between males and females. While studies on human blood during migraine attacks have reported no change in TNF-α levels and often inconsistent results for IL-1β and IL-6 levels, serial analysis of cytokines in jugular venous blood during migraine attacks revealed consistently increased IL-1β, IL-6, and TNF-α. In a study on the interictal period, researchers reported higher levels of TNF-α and IL-6 compared to controls and no change regarding IL-1β levels. Saliva-based tests suggest that IL-1β might be useful in discriminating against migraine. Patients with migraine may benefit from a cytokine perspective on the pathogenesis of migraine, as there have been several encouraging reports suggesting new therapeutic avenues.

Enlightening the association between TNF-α -308 G > A and migraine: a meta-analysis with meta-regression and trial sequential analysis

BACKGROUND

Migraine is a complex neurological disorder that is characterized by a "lower threshold of neuronal hyperexcitability" with distinctive periodicity and complex vascular dysfunction. Genetic factors have impacted incredibly on the susceptibility of migraine and one such example is the TNF-α 308G > A.

AIM

Therefore, we aim to provide a glimpse of the association of the TNF-α 308G > A risk on the susceptibility of migraine.

METHOD

The pooled odds ratio with the associated 95% of confidence interval were calculated using different genetic models. Heterogeneity was accessed by using Cochran's Q Test and I² statistics and Begg's and Egger's tests were used for finding the publication bias, tests were two-sided, and a p-value of < 0.05 was considered statistically significant. The Trial Sequential Analysis with Meta-regression Analysis were also utilized to find out the sample size requirement for meta-analysis to avoid type I error and source of heterogeneity respectively.

RESULT

A total of 13 studies with cases: 7193 and controls: 23,091 were included and after using different genetic models, no overall association with migraine and its clinical subtype migraine with aura was observed (Allele model "OR: 1.28, 95% C.I. [0.96-1.69] and OR: 0.99,95% C.I. [0.69-1.42]) respectively. Interestingly, after sub-grouping using the "ethnicity criteria" in the migraine group, it was observed that the allelic genetic model and the dominant model were found to be significantly associated with the Asian ethnic group (OR: 1.79, 95% C.I. [1.13-2.84], and OR: 1.85, 95% C.I. [1.0927; 3.1580].

CONCLUSION

In conclusion, the present meta-analysis has provided evidence that 308G > A increases the risk of migraine only in the Asian population.

Polymorphisms of the Proinflammatory Cytokine Genes Modulate the Response to NSAIDs but Not to Triptans in Migraine Attacks

Migraine is a common neurovascular disorder characterized by recurrent episodes of headache and associated neurological symptoms. At present, a significant portion of patients do not obtain a satisfactory response to acute pain-relieving therapies, including NSAIDs and triptans. In this context, pharmacogenetics plays a key role in the understanding of such a diverse response. In order to investigate whether functional polymorphisms in proinflammatory cytokine genes (IL-1α, IL-1β, IL-1RN; IL-6 and TNF-α) may influence the response to acute treatment, 313 consecutive patients with episodic migraine without aura were enrolled. Pain relief by administration of NSAIDs or triptans for three consecutive migraine attacks was evaluated. We found a significant association between A allele of the TNF-α promoter (−308 A/G) and a lack of efficacy after NSAID administration (p < 0.01, OR 2.51, 95% CI: 1.33 < OR < 4.75 compared to the G allele). Remaining polymorphisms had no significant effect on pain relief. Our study showed that a functional polymorphism in the TNF-α gene significantly modulates the clinical response to NSAID administration in acute attacks. Patients with higher production of the active cytokine during stress showed a significantly lower anti-migraine effect. Our results further support a role for TNF-α in the pathophysiological mechanisms of migraine attack.

Immunological findings in patients with migraine and other primary headaches: a narrative review

Experimental findings suggest an involvement of neuroinflammatory mechanisms in the pathophysiology of migraine. Specifically, preclinical models of migraine have emphasized the role of neuroinflammation following the activation of the trigeminal pathway at several peripheral and central sites including dural vessels, the trigeminal ganglion, and the trigeminal nucleus caudalis. The evidence of an induction of inflammatory events in migraine pathophysiological mechanisms has prompted researchers to investigate the human leukocyte antigen (HLA) phenotypes as well as cytokine genetic polymorphisms in order to verify their potential relationship with migraine risk and severity. Furthermore, the role of neuroinflammation in migraine seems to be supported by evidence of an increase in pro-inflammatory cytokines, both ictally and interictally, together with the prevalence of Th1 lymphocytes and a reduction in regulatory lymphocyte subsets in peripheral blood of migraineurs. Cytokine profiles of cluster headache (CH) patients and those of tension-type headache patients further suggest an immunological dysregulation in the pathophysiology of these primary headaches, although evidence is weaker than for migraine. The present review summarizes available findings to date from genetic and biomarker studies that have explored the role of inflammation in primary headaches.

The Role of Endothelial Dysfunction in the Pathophysiology and Cerebrovascular Effects of Migraine: A Narrative Review

Background and Purpose

Migraine is a complex neurovascular disorder whose triggers are not entirely understood. Endothelial dysfunction might play a role in migraine, and there have been numerous reports on endothelium dysfunction and migraine pathophysiology, but their reciprocal cause–effect relationship remains unclear. This review reports the current evidence on endothelium dysfunction, its link with migraine, and its possible consequences for cerebral hemodynamics.

Methods

We performed a systematic literature search of PubMed up to March 2020. We included 115 articles in a narrative review.

Results

Several studies have demonstrated that endothelium dysfunction may play an important role in migraine. Despite the lack of specific biomarkers, there is evidence of oxidative stress and inflammation—two of the primary causes of endothelial damage—in migraine. The main consequences of endothelial dysfunction are increased vascular tone, thrombosis, inflammation, and increased vascular permeability. As a consequence of oxidative stress, the activity of endothelin-1 is not counterbalanced by nitric oxide (NO), whose levels decrease to lead to vasoconstriction and a possible contribution to cortical spreading depression. NO is involved in pain perception via the cyclic guanosine monophosphate (cGMP) pathway and the induction of calcitonin gene-related peptide. Oxidative stress may induce a hypercoagulable state that mainly affects platelet function through different mechanisms. Endothelial dysfunction seems to be particularly pronounced in migraine with aura (MA). Endothelial dysfunction in migraine particularly involves intracranial vessels, since flow-mediated dilation cannot detect overt peripheral vascular dysfunction.

Conclusions

Endothelial dysfunction is a vascular risk marker. How it impacts migraine, and particularly MA, needs to be understood better by defining its possible role in increasing the stroke risk in migraine patients.

Association between tumor necrosis factor alpha and lymphotoxin alpha gene polymorphisms and migraine occurrence among Jordanians

Inflammatory reactions in the body have been shown to contribute to migraine development. Therefore, genes involved in the inflammatory pathways might play a role in the susceptibility and development of migraine. In this study, polymorphisms in tumor necrosis factor alpha (TNFα) and lymphotoxin alpha (LTA) genes were tested for association with migraine. A total of 398 participants (198 migraine patients and 200 controls) were recruited in the study. Serum TNF level was measured using a sandwich ELISA kit. Lymphocytes' and monocytes' counts were obtained from a differential complete blood count profile. Participants' DNA was extracted and genotyped for rs1800629 and rs1799724 in TNFα, and rs909253 in LTA. Controls had a significantly higher mean lymphocyte count (P = 0.018), while the mean monocyte count and serum TNFα levels did not differ between the two groups (P > 0.05). With respect to gene polymorphisms, the rs1800629 and rs1799724 variants showed significant association with migraine in all subjects, and in males and females when analyzed separately (P < 0.001). The rs909253 did not show any statistical difference in frequencies among the two groups (P > 0.05). Having the A allele in rs1800629 was associated with a higher risk of migraine in both male (OR, 95%; CI, G/A = 3.79 [1.87-7.69]; A/A = 14.22 [1.67-121.14]; P < 0.01) and female (OR, 95%; G/A = 2.54 [1.47-4.38]; A/A = 2.52 [1.12-5.69]; P < 0.001) subjects. In conclusion, rs1800629 and rs1799724 in TNFα showed significant association with migraine among the Jordanian population.

Tumor Necrosis Factor (TNF) -308G>A, Nitric Oxide Synthase 3 (NOS3) +894G>T Polymorphisms and Migraine Risk: A Meta-Analysis

Background and Objective

Conflicting data have been reported on the association between tumor necrosis factor (TNF) –308G>A and nitric oxide synthase 3 (NOS3) +894G>T polymorphisms and migraine. We performed a meta-analysis of case-control studies to evaluate whether the TNF –308G>A and NOS3 +894G>T polymorphisms confer genetic susceptibility to migraine.

Method

We performed an updated meta-analysis for TNF –308G>A and a meta-analysis for NOS3 +894G>T based on studies published up to July 2014. We calculated study specific odds ratios (OR) and 95% confidence intervals (95% CI) assuming allele contrast, dominant model, recessive model, and co-dominant model as pooled effect estimates.

Results

Eleven studies in 6682 migraineurs and 22591 controls for TNF –308G>A and six studies in 1055 migraineurs and 877 controls for NOS3 +894G>T were included in the analysis. Neither indicated overall associations between gene polymorphisms and migraine risk. Subgroup analyses suggested that the “A” allele of the TNF –308G>A variant increases the risk of migraine among non-Caucasians (dominant model: pooled OR = 1.82; 95% CI 1.15 – 2.87). The risk of migraine with aura (MA) was increased among both Caucasians and non-Caucasians. Subgroup analyses suggested that the “T” allele of the NOS3 +894G>T variant increases the risk of migraine among non-Caucasians (co-dominant model: pooled OR = 2.10; 95% CI 1.14 – 3.88).

Conclusions

Our findings appear to support the hypothesis that the TNF –308G>A polymorphism may act as a genetic susceptibility factor for migraine among non-Caucasians and that the NOS3 +894G>T polymorphism may modulate the risk of migraine among non-Caucasians.

Migraine genetics: current findings and future lines of research

In the last two decades, migraine research has greatly advanced our current knowledge of the genetic contributions and the pathophysiology of this common and debilitating disorder. Nonetheless, this knowledge still needs to grow further and to translate into more effective treatments. To date, several genes involved in syndromic and monogenic forms of migraine have been identified, allowing the generation of animal models which have significantly contributed to current knowledge of the mechanisms underlying these rare forms of migraine. Common forms of migraine are instead posing a greater challenge, as they may most often stem from complex interactions between multiple common genetic variants, with environmental triggers. This paper reviews our current understanding of migraine genetics, moving from syndromic and monogenic forms to oligogenic/polygenic migraines most recently addressed with some success through genome-wide association studies. Methodological issues in study design and future perspectives opened by biomarker research will also be briefly addressed.

Influence of tumor necrosis factor alpha gene promoter polymorphisms and its serum level on migraine susceptibility in Egyptian patients

BACKGROUND

Migraine is a common chronic neurological disorder with still largely unknown pathogenesis. We aimed to explore the possible role of tumor necrosis factor alpha (TNF-α) gene polymorphisms as risk factors of migraine, and whether they influence the TNF-α level.

MATERIALS AND METHODS

Two hundred patients with migraine and 200 controls were enrolled in this study. Polymorphisms of TNF-α gene were detected using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Serum TNF-α level was measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

TNF-α-308 GA, AA genotypes and A allele, TNF-α-857 CT genotype and T allele were associated with increased risk of migraine, while the TNF-α-238 polymorphism was not. TNF-α-308 GA, AA genotypes and A allele or AA genotype were associated with increased risk of migraine with aura (MA) and migraine without aura (MO) respectively; this was more significant in female patients with MA than in males. TNF-α-857 CT genotype was associated with increased risk of MO, or MA in females or males. While -857T allele was significantly associated with MO or MA in males and with MA only in females. On the other hand, we didn't find any significant associations of TNF-α-238 polymorphism with MO, or MA in males or females. TNF-α levels were higher in patients with migraine, MA, or MO than in controls (P<0.001).

CONCLUSION

TNF-α polymorphisms were associated with migraine, MA, or MO in Egyptians.

Effects of tumor necrosis factor-β (TNF-β) 252A>G polymorphism on the development of migraine: a meta-analysis

Background and Objective

Genetic factors including TNF-β have been considered as important components in the aetiology of migraine. Many studies have investigated the association between TNF-β 252A>G polymorphism and migraine risk, with debatable results. This study was designed to examine whether the TNF-β 252A>G polymorphism confers genetic susceptibility to migraine in diverse populations.

Method

Studies eligible for this meta-analysis were searched in the PubMed, Embase, and CNKI by using the keywords “tumor necrosis factor”, “TNF”, “252A>G”, “rs909253”, “polymorphism”, “polymorphisms”, “variant”, “SNP”, combined with “migraine” or “migraine with aura (MA)” or “migraine without aura (MO)”. Pooled ORs and 95% CI were appropriately calculated using the fixed-effect model.

Results

We finally included a total of seven studies, providing 5 557 migraineurs and 20 543 unrelated healthy controls. Meta-analysis results showed no statistical evidence of a significant association between TNF-β 252A>G polymorphism and overall migraine risk. Stratified analyses by type of migraine and gender revealed similar results. Interestingly, an OR with 95% CI representing an increased migraine risk was indicated in Asians under the recessive model (GG vs. AG + AA: OR, 1.38; 95%CI, 1.04–1.84; P for heterogeneity, 0.665).

Conclusions

Our findings appear to support the hypothesis that genetic variability of 252A>G polymorphism in TNF region may modulate risk of migraine in the population of Asian ancestry.

Investigation of chemokine receptor CCR2V64Il gene polymorphism and migraine without aura in the Iranian population

Background and Objectives. Migraine is a multifactorial common neurovascular disease with a polygenic inheritance. Inflammation plays an important part in migraine pathophysiology. C-C chemokine receptor 2 (CCR2) is an important chemokine for monocyte aggregation and transendothelial monocyte migration. The aim of our study was to investigate the association of migraine with CCR2V64Il polymorphism in the Iranian population. Methods. We assessed 103 patients with newly diagnosed migraine and 100 healthy subjects. Genomic DNA samples were extracted from peripheral blood and genotypes of CCR2V64Il gene polymorphism were determined. For measuring the severity of headache, every patient filled out the MIGSEV questionnaire. Results. There were no significant differences in the distribution of both 64Il allele and heterozygote (GA) genotype of CCR2 gene polymorphism (P = 0.396; OR = 0.92, 95% CI = 0.50–1.67 and P = 0.388; OR = 0.91, 95% CI = 0.47–1.73, resp.) between case and control groups. There was no significant difference of alleles frequency between three grades of MIGSEV (P = 0.922). Conclusions. In conclusion our results revealed no association between CCR2V64Il polymorphism and susceptibility to migraine and also headache severity in the Iranian population.

Genetic variation in cytokine-related genes and migraine susceptibility

Migraine is classified by the World Health Organization (WHO) as being one of the top 20 most debilitating diseases. According to the neurovascular hypothesis, neuroinflammation may promote the activation and sensitisation of meningeal nociceptors, inducing the persistent throbbing headache characterized in migraine. The tumor necrosis factor (TNF) gene cluster, made up of TNFα, lymphotoxin α (LTA), and lymphotoxin β (LTB), has been implicated to influence the intensity and duration of local inflammation. It is thought that sterile inflammation mediated by LTA, LTB, and TNFα contributes to threshold brain excitability, propagation of neuronal hyperexcitability and thus initiation and maintenance of a migraine attack. Previous studies have investigated variants within the TNF gene cluster region in relation to migraine susceptibility, with largely conflicting results. The aim of this study was to expand on previous research and utilize a large case-control cohort and range of variants within the TNF gene cluster to investigate the role of the TNF gene cluster in migraine. Nine single nucleotide polymorphisms (SNPs) were selected for investigation as follows: rs1800683, rs2229094, rs2009658, rs2071590, rs2239704, rs909253, rs1800630, rs1800629, and rs3093664. No significant association with migraine susceptibility was found for any of the SNPs tested, with further testing according to migraine subtype and gender also showing no association for disease risk. Haplotype analysis showed that none of the tested haplotypes were significantly associated with migraine.

Relationship between vitamin D receptor gene polymorphisms and migraine without aura in an Iranian population

BACKGROUND

Inflammation has a key role in migraine pathophysiology. Vitamin D is an effective anti-inflammatory agent. The aim of this study was to investigate the association between migraine and two vitamin D receptor (VDR) polymorphisms (TaqI and FokI) and also the relationship between VDR polymorphisms and headache severity.

METHODS

In this case-control study we assessed 103 patients with newly diagnosed migraine without aura and 100 healthy subjects. Patients filled headache impact test-6 (HIT-6) as a tool to assess headache severity.

RESULTS

Genotype frequencies of VDR were significantly different between control and migraine patients. Heterozygote genotypes (Ff and Tt) were statistically more frequent in the migraine patients than the control subjects both for TaqI gene (P = 0.018; OR = 1.81, 95% CI = 1.03-3.18) and FokI gene polymorphisms (P = 0.001; OR = 2.91, 95% CI = 1.47-5.77). Also f and t alleles were more frequent in the migraine patients. Total HIT-6 score was significantly different between FokI heterozygote and homozygote patients (60.32 ± 1.87 versus 49.87 ± 2.69, resp., P = 0.004).

CONCLUSIONS

In conclusion our results showed that TaqI and FokI gene polymorphisms are associated with migraine without aura in Iranians patients. Also headache severity in FokI heterozygote patients was significantly greater than in the homozygote patients.

Profiles of gene polymorphisms in cytokines and Toll-like receptors with higher risk for gastric cancer

BACKGROUND

Chronic inflammation and gastric carcinogenesis show a close association, so gene polymorphisms that modify the intensity of the inflammatory response may contribute to variations in gastric cancer risk.

AIMS

The purpose of this study was to investigate the combined effect of the pro- and anti-inflammatory cytokines and toll-like receptors polymorphisms on the chronic gastritis and gastric cancer risk in a Brazilian population sample.

METHODS

We evaluated 669 DNA samples (200 of gastric cancer [GC], 229 of chronic gastritis [CG], and 240 of healthy individuals [C]). Ten polymorphisms were genotyped: IL-1RN and TLR2 -196 to -174 del using the allele-specific PCR method and TNF-A (rs1800629; rs1799724), TNF-B (rs909253), IL-8 (rs4073; rs2227532), IL-10 (rs1800872) and TLR4 (rs4986790; rs4986791) using PCR-RFLP.

RESULTS

Polymorphisms TNF-A-308G/A, IL-8-251A/T, TNF-B + 252A/G and TLR4 + 1196C/T were not associated with risk of any gastric lesion. However, an association with increased risk for GC was observed for polymorphisms IL-1RNL/2 (p < 0.001), TNF-A-857C/T (p = 0.022), IL-8-845T/C (p < 0.001), IL-10-592C/A (p < 0.001), TLR2ins/del (p < 0.001), and TLR4 + 896A/G (p = 0.033). In CG, an association was observed only with polymorphisms IL-1RNL/2 and IL-10-592A/C (p < 0.001 for both). A combined analysis of these six polymorphisms associated with GC revealed a profile with two to four combined genotypes which confer a higher risk of gastric carcinogenesis, with an OR increased 2.95-fold to 50.4-fold, highlighting the combinations IL-1RN2/TNF-A-857T/IL-8-845C, IL-1RN2/IL-8-845C/TLR2del, IL-1RN2/IL-10-592A/TLR4 + 896G, IL-10-592A/TLR2del/TLR4 + 896G, and IL-1RN2/TNFA-857T/IL8-845C/TLR2del.

CONCLUSIONS

Our findings evidenced that the combined effect of polymorphisms in genes involved in the inflammatory process may potentiate the risk of gastric cancer, thus emphasizing the importance of evaluating multiple polymorphisms together.

The TNF-α-308G/A polymorphism is associated with migraine risk: A meta-analysis

Migraine is a neurasthenia and the genetic etiology has not been determined. Several studies concerning the correlation between the tumor necrosis factor (TNF)-α-308G/A polymorphism and migraine have been published, but their results remain controversial and the small samples in each study do not allow sufficient statistical power. In the present study, odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association between the polymorphism and migraine. An inverse-variance method was applied to estimate the frequency of the putative risk allele in the controls. Heterogeneity was determined using Cochran's Q test and the inconsistency index (I(2)). Begg's test and the inverted funnel plot were used to assess the publication bias. Five studies on Asian populations, comprising 985 cases and 958 controls, were included in the meta-analysis. The overall results revealed that the TNF-α-308G/A polymorphism was associated with migraine risk in Asians. The ORs were 1.735 (95% CI, 1.129-2.666) for A vs. G; 1.781 (95% CI, 1.166-2.718) for GA vs. GG; 1.821 (95% CI, 1.153-2.874) for AA+GA vs. GG. The subgroup analysis was based on migraine with aura (MA) and migraine without aura (MO) and there was a statistically significant result for MA [the OR was 1.728 (95% CI, 1.095-2.726) for GA vs. GG and 1.651 (95% CI, 1.049-2.598) for AA+GA vs. GG] but not for MO. In conclusion, the TNF-α -308G/A polymorphism was associated with migraine risk.

IL-1ra anti-inflammatory cytokine polymorphism is associated with risk of gastric cancer and chronic gastritis in a Brazilian population, but the TNF-β pro-inflammatory cytokine is not

Genetic polymorphisms in genes that codify inflammatory cytokines have been associated with gastric carcinogenesis. This study evaluated polymorphisms IL-1RN VNTR and TNFB+252A/G in a population from Southeast Brazil with regard to the risk of chronic gastritis and gastric cancer and the presence of an association of gastric lesions with risk factors such as gender, age, smoking, drinking and Helicobacter pylori infection. In this case-control study, polymorphism at IL-1RN VNTR was investigated using the allele-specific polymerase chain reaction method, while the polymerase chain reaction-restriction fragment length polymorphism technique was used to identify the TNFB+252A/G genotype in 675 Brazilian individuals [229 with chronic gastritis (CG), 200 with gastric cancer (GC) and 246 healthy individuals as controls (C)]. Multiple logistic regression analysis (log-additive, dominant, and recessive models) have not showed association of the genotype frequencies for the SNP TNFB + 252A/G with risk of CG or GC. However, as for IL-1RN VNTR it was observed significant differences in all three analysis models, with higher values of OR in recessive model, both in the GC group (OR = 3.04, 95% CI = 1.41-6.56, p < 0.01) and CG (OR = 2.32, 95% CI = 1.10-4.90, p = 0.02) compared to the C group. In addition, the multiple logistic regression showed also an association with risk factors such as male gender, older age and alcohol intake regarded GC group. So, our results indicated that the IL-1RN*2 allele may increase the risk of gastric cancer and precancerous lesions in the Southeast Brazilian population, reinforcing the importance of host genetic factors in the susceptibility to gastric cancer and the participation of cytokines in both the inflammation and the carcinogenic process.

Tumour necrosis factor gene polymorphisms and migraine: a systematic review and meta-analysis

BACKGROUND

Data on the association between TNFα and TNFβ gene polymorphisms and migraine are conflicting.

METHODS

We performed a systematic review and meta-analysis of studies published until January 2011. We used data from published papers and as provided after contact with the authors. We calculated study specific odds ratios (OR) and 95% confidence intervals (CI) assuming additive, dominant, and recessive genetic models as well as pooled effect estimates.

RESULTS

Among the ten studies identified, the best evidence is available for the TNFα -308G>A and TNFβ 252A > G polymorphisms indicating no overall association with migraine. Subgroup analyses suggested that the A allele of the TNFα -308G > A variant more than doubles the risk for migraine among populations with a heterogeneous ethnic background, which was driven by associations for migraine without aura (additive model: pooled OR = 2.87, 95% CI 1.86-4.43). Further, the risk for migraine with aura was increased among Asian populations (additive model: pooled OR = 1.71, 95% CI 1.07-2.71). Both observed effects were stronger among females than males.

CONCLUSIONS

Our results indicate no overall association between TNFα and TNFβ gene variants and migraine. However, associations differed among specific populations. Our findings need to be treated with caution and further targeted research is warranted to evaluate population-specific effects including population stratification.