BackgroundThe published findings on the link between the resistin (RETN) gene polymorphism and type 2 diabetes mellitus (T2DM) risk are still contradictory. Here, through a meta-analysis, we summarized a more precise evaluation of their connection by synthesizing existing research.MethodsPubMed, Google Scholar, and Web of Science were electronically searched, and all cited sources were manually searched. The heterogeneity of effects was tested and all statistical analyses were performed in Stata 12.0.ResultsA total of 23 studies with 10,651 cases and 14,366 controls on RETN -420C/G polymorphism were included. The overall results showed that the association of RETN -420C/G polymorphism and T2DM susceptibility was not significant [for the allelic model: odds ratio (OR) = 0.98, 95% confidence interval (CI) = 0.87–1.10, pheterogeneity <.001; I2 = 84.6%; for the dominant model: OR = 0.96, 95% CI = 0.80–1.15, pheterogeneity <.001; I2 = 87.1%; and for the recessive model: OR = 0.96, 95% CI = 0.82–1.12, pheterogeneity <.001; I2 = 56.9%] but with high heterogeneity across studies (p <.0001). Meta-regression found that the median age of T2DM participants (using age 50 as the cutoff) could be a factor in the observed variation. The RETN -420C/G polymorphism seems to be linked to an increased risk of T2DM in younger individuals [for dominant: OR = 0.84 (95% CI, 0.72–0.98; pheterogeneity <.001; I2 = 80.9%)] and decreased risk in older people [for dominant: OR = 3.14 (95% CI, 2.35–4.19; pheterogeneity = .98; I2 = 0.0%)].ConclusionsCurrent results found no evidence that the RETN -420C/G variant was linked to T2DM susceptibility, but the patient’s age appears to be a potential factor that contributed to high heterogeneity across studies. Additional high-quality and well-designed investigations are required to confirm these results.

Asthma is a complex and heterogeneous disease characterized by chronic airway inflammation, airway hyperresponsiveness, and airway remodeling. Most asthmatic patients are well-established using standard treatment strategies and advanced biologicals. However, a small group of patients who do not respond to biological treatments or are not effectively controlled by available treatment strategies remain a clinical challenge. Therefore, new therapies are urgently needed for poorly controlled asthma. Mesenchymal stem/stromal cells (MSCs) have shown therapeutic potential in relieving airway inflammation and repairing impaired immune balance in preclinical trials owing to their immunomodulatory abilities. Noteworthy, MSCs exerted a therapeutic effect on steroid-resistant asthma with rare side effects in asthmatic models. Nevertheless, adverse factors such as limited obtained number, nutrient and oxygen deprivation in vitro, and cell senescence or apoptosis affected the survival rate and homing efficiency of MSCs, thus limiting the efficacy of MSCs in asthma. In this review, we elaborate on the roles and underlying mechanisms of MSCs in the treatment of asthma from the perspective of their source, immunogenicity, homing, differentiation, and immunomodulatory capacity and summarize strategies to improve their therapeutic effect.

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