Bariatric surgery reverses natural killer (NK) cell activity and NK-related cytokine synthesis impairment induced by morbid obesity.

BACKGROUND: Obesity is related to a higher rate of infections and some types of cancer. Here we analyzed the impact of obesity and weight loss induced by Roux-en-Y gastric bypass (RYGB) on immunological parameters, i.e., cytokine productions and natural killer cell function. METHODS: We analyzed 28 morbidly obese patients before and 6 months after RYGB. Biochemical parameters were analyzed in plasma. The percent of natural killer (NK) cells, their cytotoxicity, and the production of cytokines by peripheral blood mononuclear cells were analyzed. The percent of NK cells was determined by flow cytometry and cytokine production determined by enzyme-linked immunosorbent assay. NK cytotoxicity was determined by the lactate dehydrogenase release assay. RESULTS: The weight loss 6 months following surgery was 35.3 ± 4.5 kg. RYGB also improves biochemical parameters. No significant difference was found in the percent of NK cells after surgery. We found an increase in the production of interferon-γ, interleukin (IL)-12 and IL-18, but not in IL-2, 6 months after RYGB. Cytotoxic activity of NK cells was significantly enhanced 6 months after RYGB [17.1 ± 14.7% before RYGB vs 51.8 ± 11.3% at 6 months after, at 40:1 effector to target cell ratio; p < 0.001]. We observed significant post-surgical improvement in the cytotoxic activity curve in 22 out of 28 patients (78.6%), irrespective of the target to effector cell ratio. CONCLUSIONS: The weight loss induced by RYGB modifies the production of cytokines related with NK cell function and improves its activity.

Impact of adiposity on immunological parameters.

Studies evaluating immune function in obese humans and experimental animals indicate that the excess adiposity is associated with impaired in immune responses. Obesity is related to a higher rate of infections and to some types of cancer. Nutritional, metabolic and endocrine factors are implicated in the immunological changes. The adipose tissue directly produces substances with various functions related to immune system. Furthermore, some investigations suggest that certain types of weight reduction strategies can alter the immune function. Nevertheless, long-term studies should be carried out to address whether these changes positively affects the ability of these obese individuals to control infections and tumor development.

Impact of adiposity on immunological parameters / Impacto da adiposidade nos parâmetros imunológicos

Studies evaluating immune function in obese humans and experimental animals indicate that the excess adiposity is associated with impaired in immune responses. Obesity is related to a higher rate of infections and to some types of cancer. Nutritional, metabolic and endocrine factors are implicated in the immunological changes. The adipose tissue directly produces substances with various functions related to immune system. Furthermore, some investigations suggest that certain types of weight reduction strategies can alter the immune function. Nevertheless, long-term studies should be carried out to address whether these changes positively affects the ability of these obese individuals to control infections and tumor development.

Estudos acerca da função imunológica em animais experimentais e humanos obesos indicam que o excesso de adiposidade associa-se ao prejuízo da resposta imune. A obesidade está relacionada a uma taxa maior de infecções e a alguns tipos de câncer. Fatores nutricionais, metabólicos e endócrinos estão implicados nessas alterações imunológicas. O próprio tecido adiposo produz diretamente substâncias com várias funções relacionadas ao sistema imune. Além disso, algumas investigações sugerem que certas estratégias para perda de peso podem alterar a função imune. Entretanto, estudos em longo prazo são necessários para avaliar se tais alterações afetam positivamente a capacidade desses pacientes obesos de controlar infecções e desenvolver tumores.