Age-associated aberrations in mouse cellular and humoral immune responses.

BACKGROUND AND AIMS: Several contradictions and inconsistent reports regarding nature of dysfunction of immune system with age are known. The lack of multipoint age comparisons in immune functions contributes to the observed ambiguity in understanding immunosenescence. Thus, the present study aimed at a concurrent analysis of different immune cells in an attempt to delineate the nature of dysregulation with progressive aging in mice. METHODS: 4, 8, 12 and 16 months old mice were analyzed for various immune parameters involving neutrophils, peripheral blood lymphocytes, peritoneal macrophages, splenocytes, inflamm-aging markers in plasma and humoral immune response in intestine. RESULTS: Neutrophils registered a remarkable decrease in activities of respiratory burst enzymes and phagocytosis, while macrophages recorded a decrease in TLR-2 and TLR-4 expression. MCP-1 and CRP levels increased in plasma, whereas stimulation index and CD28 expression decreased in lymphocytes. Interleukins analysis (IFN-γ, IL-4, IL-10) showed a remarkable shift towards Th2 response which further resulted in increased IgG1/IgG2a ratio and IgE levels in intestine. CONCLUSION: A decline in cell-mediated immune response, chronic inflammation and aggravation of humoral immunity was evident which conclusively suggests a skewed Th2 pathway during aging.

Comparison of innate immune activation after prolonged feeding of milk fermented with three species of Lactobacilli.

The present investigation aimed at identifying the abilities of three different species of probiotic lactobacilli to modulate cellular immune responses in mouse neutrophils and macrophages in vivo over a study period of 60 days. Neutrophil respiratory burst enzymes (cytochrome c reductase and MPO) showed remarkable increased activity (P ≤ 0.01) after consumption of milks fermented by different species of probiotics over 30 and 60 days of feeding trials. Enzyme activities (ß-galactosidase and ß-glucuronidase) and nitric oxide production also increased considerably (P ≤ 0.01) in macrophages, both in peritoneal fluid and in enriched cell cultures. The effects of enhanced enzyme activities were corroborated by simultaneous increases in the phagocytic activities of neutrophils and macrophages. The increases in cellular functions were invariably maximal during the first 30 days of study and were maintained, but did not increase, over the next 30 days. Further, Lactobacillus helveticus-fed groups were most effective at modulating neutrophil functions whereas Lactobacillus paracasei-fed groups were more potent at enhancing macrophage functions. Together, our results indicate that probiotics have strain specific effects on stimulating cellular functions while not causing excessive stimulation of the immune system over longer feeding periods, thereby resulting in maximum and stable health benefits.