Leptin and leptin-related gene polymorphisms, obesity, and influenza A/H1N1 vaccine-induced immune responses in older individuals

Correlational studies on insulin resistance and leptin gene polymorphisms in peritoneal dialysis patients

OBJECTIVES

The aim of the study was to investigate the relationship between insulin resistance (IR) and leptin (LEP) gene polymorphisms in peritoneal dialysis (PD) patients.

MATERIALS AND METHODS

From July 1, 2011 to August 1, 2011, patients who received chronic PD were chosen and divided into three groups (DM, high HOMR-IR, and low HOMR-IR). Two PCR products of LEP were sequenced and aligned and the distribution of polymorphisms was analyzed using χ(2) analysis. In addition, serum leptin level, PD conditions, and biochemical parameters according to different genotype of G-2548A and A19G were statistically analyzed (P-value<0.05). The relationship between LEP gene polymorphisms and prognosis was explored.

RESULTS

Totally 157 patients with average age of 55±15 years old were chosen. Distribution of genotype frequencies was complied with Hardy-Weinberg equilibrium. Leptin level and BMI (body mass index) of the GG genotype of G-2548A were higher than that of GA or AA. The fasting glucose, cholesterol, etc. of AA genotype were lower, and the nPCR was higher than the two other genotypes. Serum leptin level and BMI of AA genotype of A19G was higher than GA and GG genotypes; meanwhile, fasting blood glucose of that genotypes was the highest. In addition, survival rate of AA group of A19G was very low.

CONCLUSION

The G-2548A and A19G polymorphisms were correlated with serum leptin level and IR. Leptin A19G polymorphism may be prognostic for PD patients. This study may facilitate early intervention for IR in PD patients.

The weight of obesity on the human immune response to vaccination

Despite the high success of protection against several infectious diseases through effective vaccines, some sub-populations have been observed to respond poorly to vaccines, putting them at increased risk for vaccine-preventable diseases. In particular, the limited data concerning the effect of obesity on vaccine immunogenicity and efficacy suggests that obesity is a factor that increases the likelihood of a poor vaccine-induced immune response. Obesity occurs through the deposition of excess lipids into adipose tissue through the production of adipocytes, and is defined as a body-mass index (BMI) ≥ 30 kg/m(2). The immune system is adversely affected by obesity, and these "immune consequences" raise concern for the lack of vaccine-induced immunity in the obese patient requiring discussion of how this sub-population might be better protected.

Inverse associations between obesity indicators and thymic T-cell production levels in aging atomic-bomb survivors

Reduction of the naive T-cell population represents a deteriorating state in the immune system that occurs with advancing age. In animal model studies, obesity compromises the T-cell immune system as a result of enhanced adipogenesis in primary lymphoid organs and systemic inflammation. In this study, to test the hypothesis that obesity may contribute to the aging of human T-cell immunity, a thousand atomic-bomb survivors were examined for obesity status and ability to produce naive T cells, i.e., T-cell receptor excision circle (TREC) numbers in CD4 and CD8 T cells. The number of TRECs showed a strong positive correlation with naive T cell numbers, and lower TREC numbers were associated with higher age. We found that the TREC number was inversely associated with levels of obesity indicators (BMI, hemoglobin A1c) and serum CRP levels. Development of type-2 diabetes and fatty liver was also associated with lower TREC numbers. This population study suggests that obesity with enhanced inflammation is involved in aging of the human T-cell immune system. Given the fact that obesity increases the risk of numerous age-related diseases, attenuated immune competence is a possible mechanistic link between obesity and disease development among the elderly.