Heme impairs prostaglandin E2 and TGF-beta production by human mononuclear cells via Cu/Zn superoxide dismutase: insight into the pathogenesis of severe malaria.
ABSTRACT In many hemolytic disorders, such as malaria, the release of free heme has been involved in the triggering of oxidative stress and tissue damage. Patients presenting with severe forms of malaria commonly have impaired regulatory responses. Although intriguing, there is scarce data about the involvement of heme on the regulation of immune responses. In this study, we investigated the relation of free heme and the suppression of anti-inflammatory mediators such as PGE(2) and TGF-beta in human vivax malaria. Patients with severe disease presented higher hemolysis and higher plasma concentrations of Cu/Zn superoxide dismutase (SOD-1) and lower concentrations of PGE(2) and TGF-beta than those with mild disease. In addition, there was a positive correlation between SOD-1 concentrations and plasma levels of TNF-alpha. During antimalaria treatment, the concentrations of plasma SOD-1 reduced whereas PGE(2) and TGF-beta increased in the individuals severely ill. Using an in vitro model with human mononuclear cells, we demonstrated that the heme effect on the impairment of the production of PGE(2) and TGF-beta partially involves heme binding to CD14 and depends on the production of SOD-1. Aside from furthering the current knowledge about the pathogenesis of vivax malaria, the present results may represent a general mechanism for hemolytic diseases and could be useful for future studies of therapeutic approaches.
SourceAvailable from: Bruno Bezerril Andrade[Show abstract] [Hide abstract]
ABSTRACT: DDX39B (BAT1) encodes an RNA helicase known to regulate expression of TNF and IL-6. Elevated levels of these two cytokines are associated with increased severity of clinical malaria. The aim of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in the DDX39B, TNF and IL6 genes and the clinical outcomes of patients with Plasmodium vivax malaria.Malaria Journal 07/2014; 13(1):278. DOI:10.1186/1475-2875-13-278 · 3.49 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Nitric oxide (NO) and carbon monoxide (CO) are gasotransmitters that suppress the development of severe forms of malaria associated with Plasmodium infection. Here, we addressed the mechanism underlying their protective effect against experimental cerebral malaria (ECM), a severe form of malaria that develops in Plasmodium-infected mice, which resembles, in many aspects, human cerebral malaria (CM). NO suppresses the pathogenesis of ECM via a mechanism involving (1) the transcription factor nuclear factor erythroid 2-related factor 2 (NRF-2), (2) induction of heme oxygenase-1 (HO-1), and (3) CO production via heme catabolism by HO-1. The protection afforded by NO is associated with inhibition of CD4(+) T helper (TH) and CD8(+) cytotoxic (TC) T cell activation in response to Plasmodium infection via a mechanism involving HO-1 and CO. The protective effect of NO and CO is not associated with modulation of host pathogen load, suggesting that these gasotransmitters establish a crosstalk-conferring disease tolerance to Plasmodium infection.
[Show abstract] [Hide abstract]
ABSTRACT: Malaria is one of the most serious infectious diseases in humans and responsible for approximately 500 million clinical cases and 500 thousand deaths annually. Acquired adaptive immune responses control parasite replication and infection-induced pathologies. Most infections are clinically silent which reflects on the ability of adaptive immune mechanisms to prevent the disease. However, a minority of these can become severe and life-threatening, manifesting a range of overlapping syndromes of complex origins which could be induced by uncontrolled immune responses. Major players of the innate and adaptive responses are interferons. Here, we review their roles and the signaling pathways involved in their production and protection against infection and induced immunopathologies.Mediators of Inflammation 01/2014; 2014:243713. DOI:10.1155/2014/243713 · 2.42 Impact Factor
Bruno Bezerril Andrade