IL-35 polymorphisms and cognitive decline did not show any association in patients with coronary heart disease over a 2-year period: A retrospective observational study (STROBE compliant)

Association of inflammation and cognition in the elderly: A systematic review and meta-analysis

Background

The development of mild cognitive impairment (MCI) and Alzheimer's disease (AD) may be associated with an inflammatory process. Inflammatory cytokines may be a surrogate for systemic inflammation leading to worsening neurological function. We aim to investigate the association between cognitive impairment and inflammation by pooling and analyzing the data from previously published studies.

Methods

We performed a systematic literature search on MEDLINE, PubMed, Embase, Web of Science, and Scopus for prospective longitudinal and cross-sectional studies evaluating the relationship between inflammation and cognitive functions.

Results

A total of 79 articles were included in our systematic review and meta-analysis. Pooled estimates from cross-sectional studies have demonstrated an increased level of C-reactive protein (CRP) [Hedges's g 0.35, 95% CI (0.16, 0.55), p < 0.05], IL-1β [0.94, 95% CI (-0.04, 1.92), p < 0.05], interleukin-6 (IL-6) [0.46, 95% CI (0.05, 0.88), p < 0.005], TNF alpha [0.22, 95% CI (-0.24, 0.68), p < 0.05], sTNFR-1 [0.74, 95% CI (0.46, 1.02), p < 0.05] in AD compared to controls. Similarly, higher levels of IL-1β [0.17, 95% CI (0.05, 0.28), p < 0.05], IL-6 [0.13, 95% CI (0.08, 0.18), p < 0.005], TNF alpha [0.28, 95% CI (0.07, 0.49), p < 0.05], sTNFR-1 [0.21, 95% CI (0.05, 0.48), p < 0.05] was also observed in MCI vs. control samples. The data from longitudinal studies suggested that levels of IL-6 significantly increased the risk of cognitive decline [OR = 1.34, 95% CI (1.13, 1.56)]. However, intermediate levels of IL-6 had no significant effect on the final clinical endpoint [OR = 1.06, 95% CI (0.8, 1.32)].

Conclusion

The data from cross-sectional studies suggest a higher level of inflammatory cytokines in AD and MCI as compared to controls. Moreover, data from longitudinal studies suggest that the risk of cognitive deterioration may increase by high IL-6 levels. According to our analysis, CRP, antichymotrypsin (ACT), Albumin, and tumor necrosis factor (TNF) alpha may not be good surrogates for neurological degeneration over time.

Serum levels and genetic variation of IL-35 are associated with multiple sclerosis: a population-based case-control study

This study aimed to investigate the association between serum levels and polymorphic variants of IL-35 with susceptibility, clinical features, and disease severity in multiple sclerosis (MS) patients.This case-control study recruited 186 MS patients and 195 sex- and age-matched healthy controls. Serum levels and polymorphic variants of IL-35 were determined by ELISA and restriction fragment length polymorphism (RFLP)-PCR or high resolution melting (HRM) analysis methods, respectively. In addition, by in silico analysis, we evaluated the location and function of the polymorphism.Serum levels of IL-35 were significantly lower in the patients than those of healthy controls (49.3 ± 3.7 vs. 69.5 ± 7.8, p = 0.009). EBI3 rs4740 polymorphism of IL-35 was associated with 2.2-fold increased risk of MS susceptibility (95% CI, 1.3-3.9, p = 0.005). However, there were no differences in the genotype distribution and allele frequencies of IL-35 rs568408 between the patients and controls (p > 0.05). In silico results showed that variation in IL-12A and EBI3 may affect on protein pathways of the cells and different components of the immune system such as NF-κB and INF-γ.The results show that IL-35 polymorphisms might be a genetic risk factor for the development of MS.