Circulating Interleukins and Risk of Multiple Sclerosis: A Mendelian Randomization Study

Molecular mechanisms underlying Tao-Hong-Si-Wu decoction treating hyperpigmentation based on network pharmacology, Mendelian randomization analysis, and experimental verification

CONTEXT

Hyperpigmentation, a common skin condition marked by excessive melanin production, currently has limited effective treatment options.

OBJECTIVE

This study explores the effects of Tao-Hong-Si-Wu decoction (THSWD) on hyperpigmentation and to elucidate the underlying mechanisms.

MATERIALS AND METHODS

We employed network pharmacology, Mendelian randomization, and molecular docking to identify THSWD's hub targets and mechanisms against hyperpigmentation. The Cell Counting Kit-8 (CCK-8) assay determined suitable THSWD treatment concentrations for PIG1 cells. These cells were exposed to graded concentrations of THSWD-containing serum (2.5%, 5%, 10%, 15%, 20%, 30%, 40%, and 50%) and treated with α-MSH (100 nM) to induce an in vitro hyperpigmentation model. Assessments included melanin content, tyrosinase activity, and Western blotting.

RESULTS

ALB, IL6, and MAPK3 emerged as primary targets, while quercetin, apigenin, and luteolin were the core active ingredients. The CCK-8 assay indicated that concentrations between 2.5% and 20% were suitable for PIG1 cells, with a 50% cytotoxicity concentration (CC50) of 32.14%. THSWD treatment significantly reduced melanin content and tyrosinase activity in α-MSH-induced PIG1 cells, along with downregulating MC1R and MITF expression. THSWD increased ALB and p-MAPK3/MAPK3 levels and decreased IL6 expression in the model cells.

DISCUSSION AND CONCLUSION

THSWD mitigates hyperpigmentation by targeting ALB, IL6, and MAPK3. This study paves the way for clinical applications of THSWD as a novel treatment for hyperpigmentation and offers new targeted therapeutic strategies.

Mendelian Randomization Analysis of Circulating Cytokines and Risk of Autoimmune Neuroinflammatory Diseases

Background

Cytokines act a vital role in autoimmune neuroinflammatory diseases (ANDs) with undetermined causal relationships. Mendelian randomization (MR) analysis was performed to estimate the causal effects of circulating levels of cytokines on the risk of ANDs.

Methods

The causal relationship between 34 circulating cytokines and 4 kinds of ANDs, including multiple sclerosis (MS), neuromyelitis optica (NOM), chronic inflammatory demyelinating polyneuropathy (CIDP) and myasthenia gravis (MG) were explored using four methods of MR analysis. MR-PRESSO, MR-Egger regression methods and Cochran's Q statistic were utilized to identify the instrumental variables (IVs) with potential pleiotropy and heterogeneity. The Bonferroni correction was used for multiple group comparisons. P-value less than 3.68E-04 (0.05/ (34*4)) was considered statistically significant.

Results

Negative causal effects of circulating levels of interleukin (IL)-8 (OR = 0.648, 95% CI: 0.494-0.851, P = 0.002) on risk of MS, chemokine (C-C Motif) ligand (CCL)-5 (OR = 0.295, 95% CI: 0.103-0.841, P = 0.022) and stem cell growth factor-beta (SCGF-β) (OR = 0.745, 95% CI: 0.565-0.984, P = 0.038) on risk of CIDP, as well as positive causal effects of circulating levels of IL-2 receptor α (IL-2Rα) (OR = 1.216, 95% CI: 1.120-1.320, P = 3.20E-06) and chemokine C-X-C motif ligand (CXCL)-10 (OR = 1.404, 95% CI: 1.094-1.803, P = 0.008) on MS were observed. Nevertheless, only IL-2Rα still had a causal effect on MS after Bonferroni correction.

Conclusion

The results identify a genetically predicted causal effect of IL-2Rα, IL-8 and CXCL-10 on MS, CCL-5 and SCGF-β on CIDP.

Unraveling the causal role of immune cells in gastrointestinal tract cancers: insights from a Mendelian randomization study

Background

Despite early attempts, the relationship between immune characteristics and gastrointestinal tract cancers remains incompletely elucidated. Hence, rigorous and further investigations in this domain hold significant clinical relevance for the development of novel potential immunotherapeutic targets.

Methods

We conducted a two-sample Mendelian randomization (MR) analysis using the tools available in the "TwoSampleMR" R package. The GWAS data for these 731 immune traits were sourced from the GWAS Catalog database. Concurrently, data on gastrointestinal tract cancers, encompassing malignant tumors in the esophagus, stomach, small intestine, colon, and rectum, were extracted from the FinnGen database. The immune traits subjected to MR analysis predominantly fall into four categories: median fluorescence intensities (MFI), relative cell (RC), absolute cell (AC), and morphological parameters (MP). To ensure the reliability of our findings, sensitivity analyses were implemented to address robustness, account for heterogeneity, and alleviate the impact of horizontal pleiotropy.

Results

A total of 78 immune traits causally linked to gastrointestinal tract cancers were identified, encompassing esophageal cancer (12 traits), gastric cancer (13 traits), small intestine cancer (22 traits), colon cancer (12 traits), and rectal cancer (19 traits). Additionally, 60 immune traits were recognized as protective factors associated with gastrointestinal tract cancers, distributed across esophageal cancer (14 traits), gastric cancer (16 traits), small intestine cancer (7 traits), colon cancer (14 traits), and rectal cancer (9 traits). Furthermore, it was observed that seven immune traits are causally related to gastrointestinal tract cancers in at least two locations. These traits include "CCR2 on CD14- CD16+ monocyte," "CD19 on IgD+ CD38-," "CD19 on IgD+ CD38- naive," "CD25hi CD45RA+ CD4 not Treg AC," "CD27 on unsw mem," "CD28 on CD39+ activated Treg," and "CD45 on CD4+."

Conclusion

This study elucidates a causal link between immune cells and gastrointestinal tract cancers at various sites through genetic investigation. The findings of this research open up new perspectives and resources for exploring tumor prevention strategies and immunotherapeutic targets.

The Role of Selected Interleukins in the Development and Progression of Multiple Sclerosis-A Systematic Review

Multiple sclerosis is a disabling inflammatory disorder of the central nervous system characterized by demyelination and neurodegeneration. Given that multiple sclerosis remains an incurable disease, the management of MS predominantly focuses on reducing relapses and decelerating the progression of both physical and cognitive decline. The continuous autoimmune process modulated by cytokines seems to be a vital contributing factor to the development and relapse of multiple sclerosis. This review sought to summarize the role of selected interleukins in the pathogenesis and advancement of MS. Patients with MS in the active disease phase seem to exhibit an increased serum level of IL-2, IL-4, IL-6, IL-13, IL-17, IL-21, IL-22 and IL-33 compared to healthy controls and patients in remission, while IL-10 appears to have a beneficial impact in preventing the progression of the disease. Despite being usually associated with proinflammatory activity, several studies have additionally recognized a neuroprotective role of IL-13, IL-22 and IL-33. Moreover, selected gene polymorphisms of IL-2R, IL-4, IL-6, IL-13 and IL-22 were identified as a possible risk factor related to MS development. Treatment strategies of multiple sclerosis that either target or utilize these cytokines seem rather promising, but more comprehensive research is necessary to gain a clearer understanding of how these cytokines precisely affect MS development and progression.

The relationship between circulating metabolites and prostate hyperplasia: a Mendelian randomization study

BACKGROUND

Circulating metabolites (CM) play a pivotal role in our overall health, yet the current evidence concerning the involvement of diverse CM in benign prostatic hyperplasia (BPH) remains limited. Mendelian randomization (MR) offers a promising avenue to explore the potential impact of CM on BPH.

METHODS

In a forward MR analysis, a cohort of 249 circulating metabolites was employed as exposures to investigate their potential associations with BPH risk. Conversely, in a reverse MR analysis, BPH was employed as an exposure to assess its effects on CM.

RESULTS

The forward MR analysis discerned a linkage between six metabolites and BPH, with careful consideration to excluding heterogeneity and pleiotropy. Subsequently, the reverse MR analysis unveiled that nine metabolic compounds, mainly comprising phospholipids and triglycerides, potentially exhibit elevated levels in BPH patients.

CONCLUSION

Bidirectional MR analysis furnishes genetic insight into the interplay between CM and BPH. The prominence of lipids and triglycerides emerges as significant factors intricately linked to BPH risk.

The Comparison of the Selected Parameters of Brain Injury and Interleukins in the CSF in Patients Diagnosed De Novo with RRMS Compared to the Control Group

BACKGROUND

Multiple sclerosis (MS) is a chronic autoimmune disorder affecting the central nervous system (CNS). Due to the different phenotypes of the disease and non-specific symptoms of MS, there is a great need for a validated panel of biomarkers to facilitate the diagnosis, predict disease progression, and evaluate treatment outcomes.

METHODS

We determined the levels of the parameters of brain injury (NF-H, GPAF, S100B, and UCHL1) and the selected cytokines in the cerebrospinal fluid (CSF) in 101 patients diagnosed de novo with RRMS and 75 healthy controls. All determinations were made using the Bio-Plex method.

RESULTS

We found higher levels of NF-H and GFAP in the relapsing-remitting multiple sclerosis (RRMS) group compared to the controls. The concentrations of both molecules were significantly increased in patients with Gd+ lesions on brain MRI. The level of S100B did not differ significantly between the groups. UCHL1 concentrations were higher in the control group. We found some correlations between the selected cytokines, the levels of the parameters of brain injury, and the time from the first symptoms to the diagnosis of MS.

CONCLUSIONS

The role of the above molecules in MS is promising. However, further research is warranted to define their precise functions.

A systematic review of Mendelian randomization studies on multiple sclerosis

Mendelian randomization (MR) is a powerful approach for assessing the causal effect of putative risk factors on an outcome, using genetic variants as instrumental variables. The methodology and application developed in the framework of MR have been dramatically improved, taking advantage of the many public genome-wide association study (GWAS) data. The availability of summary-level data allowed to perform numerous MR studies especially for complex diseases, pinpointing modifiable exposures causally related to increased or decreased disease risk. Multiple sclerosis (MS) is a complex multifactorial disease whose aetiology involves both genetic and non-genetic risk factors and their interplay. Previous observational studies have revealed associations between candidate modifiable exposures and MS risk; although being prone to confounding, and reverse causation, these studies were unable to draw causal conclusions. MR analysis addresses the limitations of observational studies and allows to establish reliable and accurate causal conclusions. Here, we systematically reviewed the studies evaluating the causal effect, through MR, of genetic and non-genetic exposures on MS risk. Among 107 papers found, only 42 were eligible for final evaluation and qualitative synthesis. We found that, above all, low vitamin D levels and high adult body mass index (BMI) appear to be uncontested risk factors for increased MS risk.

Circulating interleukins and risk of colorectal cancer: a Mendelian randomization study

BACKGROUND

Recent studies have suggested a potential causal association between Interleukins (ILs) and Colorectal Cancer (CRC), and thus, it is important to examine the causal relationship between them using a Mendelian randomization (MR) approach.

METHODS

The instrumental variables were extracted for IL-1ra, IL-6, IL-6ra, IL-8, IL-16, IL-18, IL-27 from genome-wide association studies of European ancestry. Summary statistics of CRC were also retrieved. An inverse variance-weighted MR approach was implemented as the primary method to compute overall effects from multiple instruments. Additional MR approaches and sensitivity and heterogeneity pleiotropy analyses were also conducted respectively.

RESULTS

Our analysis suggested a causal effect between an increase of IL-8 and a reduced risk of CRC (odds ratio 0.65; 95% confidence interval, 0.43-0.98; p = 0.041) and did not provide evidence for causal effects of IL-1ra, IL-6, IL-6ra, IL-16, IL-18, IL-27. Sensitivity analyses suggested the robustness of MR results and that they were unlikely to be affected by unbalanced pleiotropy or significant heterogeneity.

CONCLUSIONS

This study investigated the role of ILs in the development of CRC and we found a causal effect between an increase of IL-8 and a reduced risk of CRC but not found evidence for causal effects of IL-1ra, IL-6, IL-6ra, IL-16, IL-18, IL-27. Sensitivity analyses suggested the robustness of MR results and that they were unlikely to be affected by unbalanced pleiotropy or significant heterogeneity.

Autoimmune Neuroinflammatory Diseases: Role of Interleukins

Autoimmune neuroinflammatory diseases are a group of disorders resulting from abnormal immune responses in the nervous system, causing inflammation and tissue damage. The interleukin (IL) family of cytokines, especially IL-1, IL-6, and IL-17, plays a critical role in the pathogenesis of these diseases. IL-1 is involved in the activation of immune cells, production of pro-inflammatory cytokines, and promotion of blood-brain barrier breakdown. IL-6 is essential for the differentiation of T cells into Th17 cells and has been implicated in the initiation and progression of neuroinflammation. IL-17 is a potent pro-inflammatory cytokine produced by Th17 cells that plays a crucial role in recruiting immune cells to sites of inflammation. This review summarizes the current understanding of the roles of different interleukins in autoimmune neuroinflammatory diseases, including multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's disease, neuromyelitis optica, and autoimmune encephalitis, and discusses the potential of targeting ILs as a therapeutic strategy against these diseases. We also highlight the need for further research to better understand the roles of ILs in autoimmune neuroinflammatory diseases and to identify new targets for treating these debilitating diseases.

Assessment of bidirectional relationships between circulating cytokines and periodontitis: Insights from a mendelian randomization analysis

Background: The purpose of this Mendelian randomization (MR) study was to assess the causal relationship between circulating cytokines and periodontitis. Materials and methods: Based on the aggregated statistics of the largest publicly available genome-wide association study (GWAS), we applied a bidirectional two-sample MR. MR analyses were conducted using Inverse variance weighted (IVW), Robust Adjusted Profile Score (RAPS), Maximum likelihood (ML), Weighted median and MR-Egger, and results obtained from IVW served as the primary outcome. Cochran Q test was used to test the heterogeneity. MR-Egger intercept test and MR polymorphism residual and outlier test (MR-PRESSO) were used for polymorphism analysis. Leave-one-out sensitivity and funnel plots were used for sensitivity analysis. Results: The IVW method indicated that interleukin 9 (IL9) had a positive causal relationship with periodontitis [odds ratio (OR) = 1.199, 95% confidence interval (CI) = 1.049-1.372, p = 0.008], and interleukin 17 (IL17) had a negative causal relationship with periodontitis (OR = 0.847, 95% CI = 0.735-0.976, p = 0.022). In bidirectional MR, periodontitis was not causally related to any of the cytokines in our study. Conclusion: Our findings provided evidence in support of potential causal associations between circulating IL9/IL17 and periodontitis.

Using an untargeted metabolomics approach to analyze serum metabolites in COVID-19 patients with nucleic acid turning negative

Background: The coronavirus disease of 2019 (COVID-19) is a severe public health issue that has infected millions of people. The effective prevention and control of COVID-19 has resulted in a considerable increase in the number of cured cases. However, little research has been done on a complete metabonomic examination of metabolic alterations in COVID-19 patients following treatment. The current project pursues rigorously to characterize the variation of serum metabolites between healthy controls and COVID-19 patients with nucleic acid turning negative via untargeted metabolomics.

Methods: The metabolic difference between 20 COVID-19 patients (CT ≥ 35) and 20 healthy controls were investigated utilizing untargeted metabolomics analysis employing High-resolution UHPLC-MS/MS. COVID-19 patients’ fundamental clinical indicators, as well as health controls, were also collected.

Results: Out of the 714 metabolites identified, 203 still significantly differed between COVID-19 patients and healthy controls, including multiple amino acids, fatty acids, and glycerophospholipids. The clinical indexes including monocytes, lymphocytes, albumin concentration, total bilirubin and direct bilirubin have also differed between our two groups of participators.

Conclusion: Our results clearly showed that in COVID-19 patients with nucleic acid turning negative, their metabolism was still dysregulated in amino acid metabolism and lipid metabolism, which could be the mechanism of long-COVID and calls for specific post-treatment care to help COVID-19 patients recover.

The Effect of Peripheral Immune Cell Counts on the Risk of Multiple Sclerosis: A Mendelian Randomization Study

Objectives

Multiple sclerosis (MS) is a complex central nervous system (CNS) demyelinating disease, the etiology of which involves the interplay between genetic and environmental factors. We aimed to determine whether genetically predicted peripheral immune cell counts may have a causal effect on MS.

Methods

We used genetic variants strongly associated with cell counts of circulating leukocyte, lymphocyte, monocyte, neutrophil, eosinophil, and basophil, in addition to some subpopulations of T and B lymphocyte, as instrumental variables (IVs) to perform Mendelian randomization (MR) analyses. The effect of immune cell counts on MS risk was measured using the summary statistics from the International Multiple Sclerosis Genetics Consortium (IMSGC) genome-wide association studies (GWAS).

Results

Our findings indicated that higher leucocyte count [odds ratio (OR), 1.24; 95% confidence interval (CI), 1.07 - 1.43; p = 0.0039] and lymphocyte count (OR, 1.17; 95% CI, 1.01 – 1.35; p = 0.0317) were causally associated with MS susceptibility. In addition, we also found that increase of genetically predicted natural killer T (NKT) cell count is also associated with an increase MS risk (OR, 1.24; 95% CI, 1.06 - 1.45; p = 0.0082).

Conclusions

These findings show that the genetic predisposition to higher peripheral immune cell counts can exert a causal effect on MS risk, which confirms the crucial role played by peripheral immunity in MS. Particularly, the causal association between NKT cell count and MS underscores the relevance of exploring the functional roles of NKT cells in disease pathogenesis in future.

The Shared Mechanism and Candidate Drugs of Multiple Sclerosis and Sjögren's Syndrome Analyzed by Bioinformatics Based on GWAS and Transcriptome Data

Objective

This study aimed to explore the shared mechanism and candidate drugs of multiple sclerosis (MS) and Sjögren's syndrome (SS).

Methods

MS- and SS-related susceptibility genes and differentially expressed genes (DEGs) were identified by bioinformatics analysis based on genome-wide association studies (GWAS) and transcriptome data from GWAS catalog and Gene Expression Omnibus (GEO) database. Pathway enrichment, Gene Ontology (GO) analysis, and protein-protein interaction analysis for susceptibility genes and DEGs were performed. The drugs targeting common pathways/genes were obtained through Comparative Toxicogenomics Database (CTD), DrugBank database, and Drug-Gene Interaction (DGI) Database. The target genes of approved/investigational drugs for MS and SS were obtained through DrugBank and compared with the common susceptibility genes.

Results

Based on GWAS data, we found 14 hub common susceptibility genes (HLA-DRB1, HLA-DRA, STAT3, JAK1, HLA-B, HLA-DQA1, HLA-DQA2, HLA-DQB1, HLA-DRB5, HLA-DPA1, HLA-DPB1, TYK2, IL2RA, and MAPK1), with 8 drugs targeting two or more than two genes, and 28 common susceptibility pathways, with 15 drugs targeting three or more than three pathways. Based on transcriptome data, we found 3 hub common DEGs (STAT1, GATA3, PIK3CA) with 3 drugs and 10 common risk pathways with 435 drugs. "JAK-STAT signaling pathway" was included in common susceptibility pathways and common risk pathways at the same time. There were 133 overlaps including JAK-STAT inhibitors between agents from GWAS and transcriptome data. Besides, we found that IL2RA and HLA-DRB1, identified as hub common susceptibility genes, were the targets of daclizumab and glatiramer that were used for MS, indicating that daclizumab and glatiramer may be therapeutic for SS.

Conclusion

We observed the shared mechanism of MS and SS, in which JAK-STAT signaling pathway played a vital role, which may be the genetic and molecular bases of comorbidity of MS with SS. Moreover, JAK-STAT inhibitors were potential therapies for MS and SS, especially for their comorbidity.

CSF sTREM2 in neurological diseases: a two-sample Mendelian randomization study

Background

Soluble triggering receptor expressed on myeloid cells 2 (sTREM2) in cerebrospinal fluid (CSF) has been described as a biomarker for microglial activation, which were observed increased in a variety of neurological disorders.

Objective

Our objective was to explore whether genetically determined CSF sTREM2 levels are causally associated with different neurological diseases by conducting a two-sample Mendelian randomization (MR) study.

Methods

Single nucleotide polymorphisms significantly associated with CSF sTREM2 levels were selected as instrumental variables to estimate the causal effects on clinically common neurological diseases, including stroke, Alzheimer’s diseases, Parkinson’s diseases, amyotrophic lateral sclerosis, multiple sclerosis, and epilepsy and their subtypes. Summary-level statistics of both exposure and outcomes were applied in an MR framework.

Results

Genetically predicted per 1 pg/dL increase of CSF sTREM2 levels was associated with higher risk of multiple sclerosis (OR = 1.038, 95%CI = 1.014–1.064, p = 0.002). Null association was found in risk of other included neurological disorders.

Conclusions

These findings provide support for a potential causal relationship between elevated CSF sTREM2 levels and higher risk of multiple sclerosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02443-9.

Body Mass Index, Interleukin-6 Signaling and Multiple Sclerosis: A Mendelian Randomization Study

Objectives

We explored whether genetically predicted increased body mass index (BMI) modulates multiple sclerosis (MS) risk through interleukin-6 (IL-6) signaling.

Methods

We performed a two-sample Mendelian randomization (MR) study using multiple genome-wide association studies (GWAS) datasets for BMI, IL-6 signaling, IL-6 levels and c-reactive protein (CRP) levels as exposures and estimated their effects on risk of MS from GWAS data from the International Multiple Sclerosis Genetics Consortium (IMSGC) in 14,802 MS cases and 26,703 controls.

Results

In univariable MR analyses, genetically predicted increased BMI and IL-6 signaling were associated with higher risk of MS (BMI: odds ratio (OR) = 1.30, 95% confidence interval (CI) = 1.15-1.47, p = 3.76 × 10-5; IL-6 signaling: OR = 1.51, 95% CI = 1.11-2.04, p = 0.01). Furthermore, higher BMI was associated with increased IL-6 signaling (β = 0.37, 95% CI = 0.32,0.41, p = 1.58 × 10-65). In multivariable MR analyses, the effect of IL-6 signaling on MS risk remained after adjusting for BMI (OR = 1.36, 95% CI = 1.11-1.68, p = 0.003) and higher BMI remained associated with an increased risk for MS after adjustment for IL-6 signaling (OR = 1.16, 95% CI =1.00-1.34, p = 0.046). The proportion of the effect of BMI on MS mediated by IL-6 signaling corresponded to 43% (95% CI = 25%-54%). In contrast to IL-6 signaling, there was little evidence for an effect of serum IL-6 levels or CRP levels on risk of MS.

Conclusion

In this study, we identified IL-6 signaling as a major mediator of the association between BMI and risk of MS. Further explorations of pathways underlying the association between BMI and MS are required and will, together with our findings, improve the understanding of MS biology and potentially lead to improved opportunities for targeted prevention strategies.

Genetics and functional genomics of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory neurodegenerative disease with genetic predisposition. Over the last decade, genome-wide association studies with increasing sample size led to the discovery of robustly associated genetic variants at an exponential rate. More than 200 genetic loci have been associated with MS susceptibility and almost half of its heritability can be accounted for. However, many challenges and unknowns remain. Definitive studies of disease progression and endophenotypes are yet to be performed, whereas the majority of the identified MS variants are not yet functionally characterized. Despite these shortcomings, the unraveling of MS genetics has opened up a new chapter on our understanding MS causal mechanisms.

Neurological Symptoms and Their Associations With Inflammatory Biomarkers in the Chronic Phase Following Traumatic Brain Injuries

BACKGROUND

The underlying biological mechanisms for neurological symptoms following a traumatic brain injury (TBI) remain poorly understood. This study investigated the associations between serum inflammatory biomarkers and neurological symptoms in the chronic phase following moderate to severe TBI.

METHODS

The serum interleukin [IL]-1β, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, and the tumor necrosis factor [TNF]-α in 72 TBI patients 6 months to 2 years post injury were measured. Neurological symptoms including depression, chronic headache, sleep disturbance, irritability, anxiety, and global neurological disability was assessed. The associations between the biomarkers and the neurological symptoms were assessed using correlation and regression analysis.

RESULTS

It was found that the most common post-injury symptom was sleep disturbance (84.7%), followed by chronic headaches (59.7%), irritability (55.6%), and depression (54.2%). TNF-α was a protective factor for chronic headache (OR = 0.473, 95% CI = 0.235-0.952). IL-6 was positively associated with sleep disturbance (r = 0.274, p = 0.021), while IL-5 and IL-12p70 were negatively associated with the degree of global neurological disability (r = -0.325, p = 0.006; r = -0.319, p = 0.007).

CONCLUSION

This study provides preliminary evidence for the association between chronic inflammation with neurological symptoms following a TBI, which suggests that anti-inflammatory could be a potential target for post-TBI neurological rehabilitation. Further research with larger sample sizes and more related biomarkers are still needed, however, to elucidate the inflammatory mechanisms for this association.

Association of Methylenetetrahydrofolate Reductase C677T Gene Polymorphisms with Mild Cognitive Impairment Susceptibility: A Systematic Review and Meta-Analysis

Background

Methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133) gene polymorphisms are related to a growing risk of Alzheimer's disease; however, whether this association applies to mild cognitive impairment (MCI) remains unclear.

Objective

We conducted this meta-analysis to evaluate the contribution of MTHFR C677T (rs1801133) gene variants to the risk of MCI.

Methods

PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases were searched from their inception to March 21, 2021, with language restricted to English or Chinese. We used fixed or random effects to examine the association between MTHFR C677T (rs1801133) gene variants and MCI susceptibility. Forest plots of pooled odds ratios (ORs) and 95% confidence intervals (CIs) were generated.

Results

Eight articles with 2,175 participants were included in the present meta-analysis. There was no significant association between MTHFR C677T (rs1801133) gene variants and MCI susceptibility under the allelic (OR, 1.318; 95% CI, 0.964–1.801; p = 0.084), dominant (OR, 1.296; 95% CI, 0.925–1.817; p = 0.132), recessive (OR, 1.397; 95% CI, 0.845–2.312; p = 0.193), heterozygous (OR, 1.031; 95% CI, 0.855–1.243; p = 0.749), or homozygous (OR, 1.506; 95% CI, 0.850–2.667; p = 0.160) models.

Conclusion

The results suggest that MTHFR C677T (rs1801133) gene polymorphisms are not associated with MCI susceptibility. However, large-scale studies covering various factors are required.