RESUMO
BACKGROUND: Chronic soil-transmitted helminth (STH) infections are associated with effects on systemic immune responses that could be caused by alterations in immune homeostasis. To investigate this, we measured the impact in children of STH infections on cytokine responses and gene expression in unstimulated blood. METHODOLOGY/PRINCIPAL FINDINGS: Sixty children were classified as having chronic, light, or no STH infections. Peripheral blood mononuclear cells were cultured in medium for 5 days to measure cytokine accumulation. RNA was isolated from peripheral blood and gene expression analysed using microarrays. Different infection groups were compared for the purpose of analysis: STH infection (combined chronic and light vs. uninfected groups) and chronic STH infection (chronic vs. combined light and uninfected groups). The chronic STH infection effect was associated with elevated production of GM-CSF (P=0.007), IL-2 (P=0.03), IL-5 (P=0.01), and IL-10 (P=0.01). Data reduction suggested that chronic infections were primarily associated with an immune phenotype characterized by elevated IL-5 and IL-10, typical of a modified Th2-like response. Chronic STH infections were associated with the up-regulation of genes associated with immune homeostasis (IDO, P=0.03; CCL23, P=0.008, HRK, P=0.005), down-regulation of microRNA hsa-let-7d (P=0.01) and differential regulation of several genes associated with granulocyte-mediated inflammation (IL-8, down-regulated, P=0.0002; RNASE2, up-regulated, P=0.009; RNASE3, up-regulated, p=0.03). CONCLUSIONS/SIGNIFICANCE: Chronic STH infections were associated with a cytokine response indicative of a modified Th2 response. There was evidence that STH infections were associated with a pattern of gene expression suggestive of the induction of homeostatic mechanisms, the differential expression of several inflammatory genes and the down-regulation of microRNA has-let-7d. Effects on immune homeostasis and the development of a modified Th2 immune response during chronic STH infections could explain the systemic immunologic effects that have been associated with these infections such as impaired immune responses to vaccines and the suppression of inflammatory diseases.
Assuntos
Ascaríase/imunologia , Sangue/imunologia , Citocinas/metabolismo , Expressão Gênica , Leucócitos Mononucleares/imunologia , Tricuríase/imunologia , Células Cultivadas , Criança , Estudos Transversais , Feminino , Perfilação da Expressão Gênica , Humanos , Masculino , Análise em MicrossériesRESUMO
Systemic administration of cytokines has shown therapeutic benefits in cancer patients; however, serious adverse effects associated with direct protein administration prevent the wide use of this approach. We have assessed the capacity of live attenuated Salmonella to act as a vector for oral cytokine-gene therapy. Salmonella orally administered to melanoma-bearing mice was found to accumulate within the tumor, reaching up to 10(5) bacteria per gram of tumor by day 21 after bacterial inoculation. Numbers of bacteria recovered from tumor did not differ from those recovered from liver or spleen at any time point. Recombinant bacteria carrying eukaryotic expression vectors encoding the murine IL-4 or IL-18 genes were administered to groups of mice with established subcutaneous melanoma tumors. We found that a single oral dose of Salmonella carrying any of the cytokine-encoding plasmids resulted in significantly increased survival time, as compared with mice that received Salmonella carrying the parental plasmid or PBS. Increased levels of IFNgamma were found in sera of animals receiving either of the cytokine-encoding bacteria, but not in mice receiving Salmonella alone or PBS. Co-administration of both recombinant bacteria maximized the production of IFNgamma. Overall these results suggest that cytokine-encoding Salmonella can be an effective and safer alternative to systemic administration of cytokines for immunotherapy of cancer.
Assuntos
Vacinas Anticâncer , Citocinas/administração & dosagem , Terapia Genética/métodos , Vetores Genéticos , Melanoma Experimental/terapia , Salmonella/genética , Animais , Interferon gama/análise , Interleucina-18/administração & dosagem , Interleucina-18/genética , Interleucina-4/administração & dosagem , Interleucina-4/genética , Camundongos , Taxa de Sobrevida , Vacinas AtenuadasRESUMO
We have used Salmonella as a delivery system for eukaryotic expression plasmids encoding cytokines, and assessed its capacity to modulate immune responses in different experimental models. Plasmids encoding mouse IL-4 and IL-18 under cytomegalovirus promoter were constructed and transformed into live attenuated Salmonella enterica serovar Typhi strain CVD 908-htrA, and Salmonella enterica serovar Typhimurium strain SL3261. We have shown that systemic as well as mucosal immunization with such constructs can influence the antibody and cytokine responses to the Salmonella carrier and to co-administered bystander antigens, as well as the specific immune response elicited during a parasitic infection. Further, we have shown that oral cytokine-therapy using Salmonella as gene vector induce antitumoral effect as demonstrated by extended survival time in melanoma-bearing mice. This approach may be particularly suited for the development of new immunotherapies with applications in parasitic infections and cancer, were alterations of the host's immune responses are usually found, and therapy-induced modulation of the immune response is likely to be required.