Cellular dormancy: A widespread phenomenon that perpetuates infectious diseases.

Under adverse environmental conditions, microorganisms are able to enter a state of cellular dormancy which consists of cell cycle arrest and interruption of multiplication. This process ensures their perpetuation in the infected host organism and enables the spread of disease. Throughout biological evolution, dormancy allowed microorganisms to persist in a harsh niche until favorable conditions for their reactivation were re-established. Here, we propose to discuss the dormancy of bacteria and protozoa pathogens focusing on the potential mechanisms and components associated with dormancy.

Galectin-3 plays a protective role in Leishmania (Leishmania) amazonensis infection.

Leishmania (L.) amazonensis is one of the species responsible for the development of cutaneous leishmaniasis in South America. After entering the vertebrate host, L. (L.) amazonensis invades mainly neutrophils, macrophages and dendritic cells. Studies have shown that gal-3 acts as a pattern recognition receptor. However, the role of this protein in the context of L. (L.) amazonensis infection remains unclear. Here, we investigated the impact of gal-3 expression on experimental infection by L. (L.) amazonensis. Our data showed that gal-3 plays a role in controlling parasite invasion, replication and the formation of endocytic vesicles. Moreover, mice with gal-3 deficiency showed an exacerbated inflammatory response. Taken together, our data shed light to a critical role of gal-3 in the host response to infection by L. (L.) amazonensis.

Experimental evidences that P21 protein controls Trypanosoma cruzi replication and modulates the pathogenesis of infection.

P21 is a protein secreted by Trypanosoma cruzi (T. cruzi). Previous studies have shown a spectrum of biological activities performed by P21 such as induction of phagocytosis, leukocyte chemotaxis and inhibition of angiogenesis. However, the activity of P21 in T. cruzi infection remains unknown. Here, we reported the role of P21 in mice harboring late T. cruzi infection. Treatment with recombinant P21 protein (rP21) reduced parasite load and angiogenesis, and induced fibrosis in the cardiac tissue of infected mice. In addition, rP21 reduced the growth of epimastigotes, inhibited intracellular replication of amastigotes and modulated the parasite cell cycle. Our data suggest that P21 controls parasite replication in the host, supporting the survival of both parasite and host.

Mechanisms of Infectivity and Evasion Derived from Microvesicles Cargo Produced by Trypanosoma cruzi.

Cell invasion by the intracellular protozoans requires interaction of proteins from both the host and the parasite. Many parasites establish chronic infections, showing they have the potential to escape the immune system; for example, Trypanosoma cruzi is an intracellular parasite that causes Chagas disease. Parasite internalization into host cell requires secreted and surface molecules, such as microvesicles. The release of microvesicles and other vesicles, such as exosomes, by different eukaryotic organisms was first observed in the late twentieth century. The characterization and function of these vesicles have recently been the focus of several investigations. In this review, we discuss the release of microvesicles by T. cruzi. The molecular content of these vesicles is composed of several molecules that take place during parasite-host cell interaction and contribute to the parasite-driven mechanism of evasion from the host immune system. These new findings appear to have a profound impact on the comprehension of T. cruzi biology and highlight novel potential strategies for developing more efficient therapeutic approaches.

Revealing the kinetics of Leishmania chagasi infection in the male genital system of hamsters.

BACKGROUND: Leishmaniasis causes alterations and lesions in the genital system, which leads to azoospermia and testicular atrophy in animals during the chronic phase of the infection. The aim of this study was to reveal the kinetics of Leishmania chagasi infection in the genital system of male golden hamsters (Mesocricetus auratus). METHODS: Animals were intraperitoneally inoculated with amastigotes from L. chagasi. At different time points animals were euthanized and genital organs processed for histo-pathological, qPCR, cytokines and testosterone detection assays. RESULTS: Our results showed a high parasite load in testis, followed by an increase of pro-inflammatory cytokines IL1-ß, TNF-α and IFN-γ, and testosterone. Subsequently, IL-4 expression was upregulated and basal parasite persistence in testis was observed using the experimental approach. CONCLUSION: Extracellular amastigotes migrated to the epididymis posing as a potential major factor of parasite persistence and venereal transmission of L. chagasi infection in hamsters.

A high throughput analysis of cytokines and chemokines expression during the course of Trypanosoma cruzi experimental oral infection.

Trypanosoma cruzi has high biological and biochemical diversity and variable tissue tropism. Here we aimed to verify the kinetics of cytokine and chemokine in situ secretion in animals infected with two distinct T. cruzi strains after oral inoculation. Also, we investigated parasite migration, residence and pathological damage in stomach, heart and spleen. Our results showed that host immune response against T. cruzi infection is an intricate phenomenon that depends on the parasite strain, on the infected organ and on the time point of the infection. We believe that a wide comprehension of host immune response will potentially provide basis for the development of immunotherapeutic strategies in order to clear parasitism and minimize tissue injury. In this context, we find that KC poses as a possible tool to be used.

Experimental evidences that P21 protein controls Trypanosoma cruzi replication and modulates the pathogenesis of infection

P21 is a protein secreted by Trypanosoma cruzi (T. cruzi). Previous studies have shown a spectrum of biological activities performed by P21 such as induction of phagocytosis, leukocyte chemotaxis and inhibition of angiogenesis. However, the activity of P21 in T. cruzi infection remains unknown. Here, we reported the role of P21 in mice harboring late T. cruzi infection. Treatment with recombinant P21 protein (rP21) reduced parasite load and angiogenesis, and induced fibrosis in the cardiac tissue of infected mice. In addition, rP21 reduced the growth of epimastigotes, inhibited intracellular replication of amastigotes and modulated the parasite cell cycle. Our data suggest that P21 controls parasite replication in the host, supporting the survival of both parasite and host.

Experimental evidences that P21 protein controls Trypanosoma cruzi replication and modulates the pathogenesis of infection

P21 is a protein secreted by Trypanosoma cruzi (T. cruzi). Previous studies have shown a spectrum of biological activities performed by P21 such as induction of phagocytosis, leukocyte chemotaxis and inhibition of angiogenesis. However, the activity of P21 in T. cruzi infection remains unknown. Here, we reported the role of P21 in mice harboring late T. cruzi infection. Treatment with recombinant P21 protein (rP21) reduced parasite load and angiogenesis, and induced fibrosis in the cardiac tissue of infected mice. In addition, rP21 reduced the growth of epimastigotes, inhibited intracellular replication of amastigotes and modulated the parasite cell cycle. Our data suggest that P21 controls parasite replication in the host, supporting the survival of both parasite and host.