Effect of obesity, lipids and adipokines on allergic rhinitis risk: a Mendelian randomization study

Association of Abnormal Body Weight and Allergic Rhinitis-A Systematic Review and Meta-Analysis

OBJECTIVE

Allergic rhinitis (AR) is a prevalent inflammatory condition of the nasal mucosa, with significant burden worldwide. While studies have demonstrated a relationship between body mass index (BMI) and other atopic diseases, its association with AR is uncertain. This study aims to clarify the association between non-normal BMI and AR.

DESIGN

According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations, independent authors screened studies for eligibility, extracted data and assessed bias of included studies using the Newcastle-Ottawa scale and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) framework. A random-effects meta-analysis was used to pool maximally covariate-adjusted estimates. Additional subgroup and bias analyses were performed.

DATA SOURCES

PubMed, Embase, Cochrane Library, SCOPUS and CINAHL were searched from inception to 14 January, 2024.

ELIGIBILITY CRITERIA

Observational studies investigating the association between non-normal BMI and AR in both children and adults.

RESULTS

We included 32 articles comprising 2,008,835 participants. The risk of bias was low (N = 20) or moderate (N = 12) and GRADE certainty of evidence was very low to low. Pooled cross-sectional analyses indicated that obese children (OR = 0.99, 95% CI = 0.96-1.03, I2 = 0%), obese adults (OR = 1.11, 95% CI = 0.92-1.33, I2 = 73%), overweight children (OR = 1.02, 95% CI = 0.98-1.06, I2 = 35%), and overweight adults (OR = 1.13, 95% CI = 0.90-1.40, I2 = 0%) showed similar odds of AR compared to controls. Additionally, longitudinal analyses did not identify any evidence for an association between overweight (OR = 1.03, 95% CI = 0.85-1.24, I2 = 29%) or underweight (OR = 1.09, 95% CI = 0.77-1.54, I2 = 72%) children and AR risk. These results remained largely robust across various subgroups and sensitivity assessments.

CONCLUSION

Abnormal BMI may not be associated with AR. This study adds to the expanding literature on the association between non-normal BMI and atopic diseases. Further prospective studies are needed to explore the longitudinal relationship between BMI and AR and the effect of weight loss interventions on AR, given the limits of existing literature.

TRIAL REGISTRATION

PROSPERO CRD42024503589.

Therapeutic Potential of Dimethyl Fumarate for the Treatment of High-Fat/High-Sucrose Diet-Induced Obesity

Obesity is characterized by an imbalance between energy intake and expenditure that triggers abnormal growth of adipose tissues. Dimethyl fumarate (DMF) and its primary active metabolite, monomethyl fumarate (MMF), are Nrf2 activators and have been recognized as strategic antioxidants. This study aimed to evaluate the potential of MMF and DMF to interfere with adipogenesis and obesity, and identify the molecular mechanisms involved. The 3T3-L1 preadipocytes were incubated with differentiation medium (MIX) and simultaneously treated with different concentrations of MMF. In addition, male C57BL/6 mice were fed a standard diet or high-fat/high-sucrose diet (HFHSD) for 16 weeks, during the last 4 of which, they received oral DMF treatment. Exposure to MMF prevented the development of MIX-induced adipogenesis by reducing the expression of transcription factors that drive adipocyte differentiation and by decreasing triglyceride levels. In addition, various antioxidant and anti-inflammatory effects were observed after treatment with MMF as evidenced by the modulation of transcription factor activities and reduction in reactive oxygen species, adipokine, proinflammatory cytokine and resistin levels. In vivo treatment with DMF reduced calorie intake, body weight, and visceral and subcutaneous fat mass in HFHSD mice. Furthermore, DMF administration led to a better glycemic response as well as lower leptin and adiponectin plasma levels in these animals. Our data demonstrate that DMF and its metabolite MMF interfere with adipogenesis and prevent the key features of diet-induced obesity. Considering DMF is already a commercial drug used to treat psoriasis and multiple sclerosis, its pharmacological application for the treatment of obesity and related metabolic disorders holds promise.

No causal association between allergic rhinitis and migraine: a Mendelian randomization study

PURPOSE

Allergic rhinitis (AR) and migraine are among the most common public health problems worldwide. Observational studies on the correlation between AR and migraine have reported inconsistent results. This study aimed to investigate the causal relationship of AR with migraine and its subtypes, including migraine with aura (MA) and migraine without aura (MO).

METHODS

Bidirectional two-sample Mendelian randomization (MR) analysis was performed with publicly available summary-level statistics of large genome-wide association studies to estimate the possible causal effects. The inverse variance-weighted method was selected for primary analysis and was supplemented with the weighted median, weighted mode, and MR-Egger methods. The causal analysis using summary effect estimates (CAUSE) were further performed to verify the causality. Several sensitivity tests, including the leave-one-out, Cochran's Q, MR-Egger intercept, and MR-PRESSO tests, were performed to assess the robustness of the results.

RESULTS

AR did not exhibit a significant causal correlation with the elevated risk of any migraine (odd ratio (OR), 0.816; 95% confidence interval (CI), 0.511-1.302; P = 0.394), MA (OR, 0.690; 95% CI 0.298-1.593; P = 0.384), or MO (OR, 1.022; 95% CI 0.490-2.131; P = 0.954). Consistently, reverse MR analysis did not reveal causal effects of any migraine or its subtypes on AR. Almost all sensitivity analyses supported the robustness of the results.

CONCLUSIONS

This MR study did not reveal a clear causal association between AR and migraine risk. More research is warranted to reveal the complex association between AR and migraine.