Immunological and non-immunological effects of cytokines and chemokines in the pathogenesis of chronic Chagas disease cardiomyopathy.

The pathogenesis of Chagas disease cardiomyopathy (CCC) is not well understood. Since studies show that myocarditis is more frequent during the advanced stages of the disease, and the prognosis of CCC is worse than that of other dilated cardiomyopathies of non-inflammatory aetiology, which suggest that the inflammatory infiltrate plays a major role in myocardial damage. In the last decade, increasing evidence has shown that inflammatory cytokines and chemokines play a role in the generation of the inflammatory infiltrate and tissue damage. CCC patients have an increased peripheral production of the inflammatory Th1 cytokines IFN-gamma and TNF-alpha when compared to patients with the asymptomatic/indeterminate form. Moreover, Th1-T cells are the main producers of IFN-gamma and TNF-alpha and are frequently found in CCC myocardial inflammatory infiltrate. Over the past several years, our group has collected evidence that shows several cytokines and chemokines produced in the CCC myocardium may also have a non-immunological pathogenic effect via modulation of gene and protein expression in cardiomyocytes and other myocardial cell types. Furthermore, genetic polymorphisms of cytokine, chemokine and innate immune response genes have been associated with disease progression. We will review the molecular and immunological mechanisms of myocardial damage in human CCC in light of recent findings.

[New concepts on the pathogenesis of chronic Chagas cardiomyopathy: myocardial gene and protein expression profiles]. / Novos conceitos em patogenia da cardiopatia chagáisica crônica: perfis de expressão gênica e proteica do miocárdio.

The pathogenesis of chronic Chagas cardiomyopathy (CCC) is still being unraveled. In the last decade, a role for inflammatory cytokines on tissue damage has been shown. The present review will address the molecular and immunological mechanisms of tissue damage on human CCC with a special focus on results obtained by our research group using genomic and proteomic approaches. The results suggest that direct modulation of myocardium gene and protein expression by inflammatory cytokines may be a new pathogenic mechanism in CCC, with therapeutic implications.

CXCL9/Mig mediates T cells recruitment to valvular tissue lesions of chronic rheumatic heart disease patients.

Rheumatic fever (RF) is an autoimmune disease triggered by Streptococcus pyogenes infection frequently observed in infants from developing countries. Rheumatic heart disease (RHD), the major sequel of RF, leads to chronic inflammation of the myocardium and valvular tissue. T cells are the main population infiltrating cardiac lesions; however, the chemokines that orchestrate their recruitment are not clearly defined. Here, we investigated the expression of chemokines and chemokine receptors in cardiac tissue biopsies obtained from chronic RHD patients. Our results showed that CCL3/MIP1α gene expression was upregulated in myocardium while CCL1/I-309 and CXCL9/Mig were highly expressed in valvular tissue. Auto-reactive T cells that infiltrate valvular lesions presented a memory phenotype (CD4(+)CD45RO(+)) and migrate mainly toward CXCL9/Mig gradient. Collectively, our results show that a diverse milieu of chemokines is expressed in myocardium and valvular tissue lesions and emphasize the role of CXCL9/Mig in mediating T cell recruitment to the site of inflammation in the heart.

Role of cytokines in mediating mechanical hypernociception in a model of delayed-type hypersensitivity in mice.

In the present study, we used the electronic version of the von Frey test to investigate the role of cytokines (TNF-alpha and IL-1beta) and chemokines (KC/CXCL-1) in the genesis of mechanical hypernociception during antigen-induced inflammation in mice. The nociceptive test consisted of evoking a hindpaw flexion reflex with a hand-held force transducer (electronic anesthesiometer) adapted with a 0.5 mm(2) polypropylene tip. The intraplantar administration of methylated bovine serum albumin (mBSA) in previously immunized (IM), but not in sham-immunized (SI) mice, induced mechanical hypernociception in a dose-dependent manner. Hypernociception induced by antigen was reduced in animals pretreated with IL-1ra and reparixin (a non-competitive allosteric inhibitor of CXCR2), and in TNF receptor type 1 deficient (TNFR1-/-) mice. Consistently, antigen challenge induced a time-dependent release of TNF-alpha, IL-1beta and KC/CXCL-1 in IM, but not in SI, mice. The increase in TNF-alpha levels preceded the increase in IL-1beta and KC/CXCL1. Antigen-induced release of IL-1beta and KC/CXCL1 was reduced in TNFR1-/- mice, and TNF-alpha-induced hypernociception was inhibited by IL-1ra and reparixin. Hypernociception induced by IL-1beta in immunized mice was inhibited by indomethacin, whereas KC/CXCL1-induced hypernociception was inhibited by indomethacin and guanethidine. Antigen-induced hypernociception was reduced by indomethacin and guanethidine and abolished by the two drugs combined. Together, these results suggest that inflammation associated with an adaptive immune response induces hypernociception that is mediated by an initial release of TNF-alpha, which triggers the subsequent release of IL-1beta and KC/CXCL1. The latter cytokines in turn stimulate the release of the direct-acting final mediators, prostanoids and sympathetic amines.

Effect of salivary gland extract of Leishmania vector, Lutzomyia longipalpis, on leukocyte migration in OVA-induced immune peritonitis.

Salivary gland extracts (SGE) from Lutzomyia longipalpis potentate L. major infection by inducing a Th2 immune response. However, the effect of SGE on the effector phase of immune response is not known. Herein, we demonstrate that SGE inhibited neutrophil migration in ovalbumin (OVA)-induced peritonitis in immunized mice. SGE pretreatment of mice inhibited OVA-induced CD4+ and CD8+ T lymphocyte migration. The OVA-induced production of TNF-alpha, IL-1beta and leukotriene B4 (LTB4), neutrophil chemotactic mediators in this model, were inhibited by SGE. On the other hand, SGE enhanced production of IL-10 and IL-4. In naive mice, SGE also blocked LTB4-induced neutrophil migration, but not that induced fMLP. Moreover, co-incubation of LTB4 (but not fMLP, TNF-alpha and MIP-1alpha) with SGE inhibited the ability of LTB4 to induce neutrophil migration in vivo and in vitro. Altogether, the results suggest that SGE has anti-inflammatory properties that are associated with inhibition of TNF-alpha and LTB4 production and/or with the neutrophil chemotactic activity of LTB4. The effectiveness of SGE in inhibiting neutrophil migration and inflammatory mediators release in a Th1 immune inflammatory response model reinforces the need for isolation of the compounds responsible for these activities, which could be used as prototypes for the development new anti-inflammatory drugs.

Aspectos imunológicos na cardiopatia chagásica crônica / Immunological features in Chagas cardiomyopathy

A patogenia da cardiomiopatia chagásica crônica ainda é pouco conhecida, e diversos mecanismos patogênicos foram propostos, como a disautonomia cardíaca, os distúrbios da circulação microvascular, e o dano tecidual imunológico-inflamatório. As observações de que a miocardite é mais frequente e intensa nos estágios mais avançados da doença e de que o prognóstico da cardiopatia chagásica crônica é pior que o de outras cardiomiopatias dilatadas de etiologia não-inflamatória sugerem que o infiltrado inflamatório desempenha papel importante no dano miocárdio. Na última década, tem sido evidenciada a participação de citocinas inflamatórias e de quimiocinas na gênese do infiltrado inflamatório e dano tecidual, assim como de polimorfismos genéticos de genes envolvidos na resposta inflamatória. Cardiopatas chagásicos apresentam produção periférica aumentada de interferon-gama e de fator de necrose tumoral alfa (TNF-alfa), comparativamente a pacientes da forma indeterminada, e linfócitos T Th1, produtores de interferon-gama e TNF-alfa, são frequentes no infiltrado inflamatório da cardiopatia chagásica crônica. Neste trabalho, revisaremos os mecanismos imunológicos e moleculares de dano miocárdico na cardiopatias chagásica crônica humana, com ênfase nos resultados obtidos pelo nosso grupo de pesquisa.

Immunological and non-immunological effects of cytokines and chemokines in the pathogenesis of chronic Chagas disease cardiomyopathy

The pathogenesis of Chagas disease cardiomyopathy (CCC) is not well understood. Since studies show that myocarditis is more frequent during the advanced stages of the disease, and the prognosis of CCC is worse than that of other dilated cardiomyopathies of non-inflammatory aetiology, which suggest that the inflammatory infiltrate plays a major role in myocardial damage. In the last decade, increasing evidence has shown that inflammatory cytokines and chemokines play a role in the generation of the inflammatory infiltrate and tissue damage. CCC patients have an increased peripheral production of the inflammatory Th1 cytokines IFN-³ and TNF-± when compared to patients with the asymptomatic/indeterminate form. Moreover, Th1-T cells are the main producers of IFN-³ and TNF-± and are frequently found in CCC myocardial inflammatory infiltrate. Over the past several years, our group has collected evidence that shows several cytokines and chemokines produced in the CCC myocardium may also have a non-immunological pathogenic effect via modulation of gene and protein expression in cardiomyocytes and other myocardial cell types. Furthermore, genetic polymorphisms of cytokine, chemokine and innate immune response genes have been associated with disease progression. We will review the molecular and immunological mechanisms of myocardial damage in human CCC in light of recent findings.