A biomarker for tegumentary and visceral leishmaniasis based on a recombinant Leishmania hypothetical protein

The measures for leishmaniasis control include the precise diagnosis of disease. However, although several recombinant antigens have been tested with this biotechnological purpose, no effective product exists, which could detects patients with the active disease, as well as differentiates them from cured and treated patients. In this study, a conserved Leishmania hypothetical protein, which was identified in Leishmania infantum parasites, but evaluated to presents high homology in the amino acid sequences between distinct parasite species, was evaluated for the diagnosis of tegumentary and visceral leishmaniasis. In addition, PBMCs collected from treated and untreated mucosal leishmaniasis (ML) and visceral leishmaniasis (VL) patients, as well as in healthy subjects living in endemic region of disease, were in vitro stimulated, when IFN-γ, IL-4 and IL-10 levels were evaluated in the cell supernatant. Regarding the serological analyses, ELISA experiments using the recombinant protein (rLiHyL) and a human serological panel revealed high sensitivity and specificity values to detect both diseases, while control antigens showed worst results. Regarding the cellular response, results showed that rLiHyL-stimulated cells produced higher IFN-γ and lower IL-4 and IL-10 levels in the supernatants. Also, the anti-protein antibody production was evaluated in these patients, and data showed higher IgG2 and lower IgG1 levels found in the treated patients and healthy controls, demonstrating the stimulation of a Th1-type response induced by the rLiHyL protein. In conclusion, this hypothetical protein can be considered as antigenic in TL and VL, as well as a vaccine candidate to be tested in future studies to protect against disease.     

Dexamethasone turns tumor antigen-presenting cells into tolerogenic dendritic cells with T cell inhibitory functions

BackgroundDendritic cells (DCs) are usually immunogenic, but they are also capable of inducing tolerance under anti-inflammatory conditions. Immunotherapy based on autologous DCs loaded with an allogeneic melanoma cell lysate (TRIMEL/DCs) induces immunological responses and increases melanoma patient survival. Glucocorticoids can suppress DC maturation and function, leading to a DC-mediated inhibition of T cell responses.MethodsThe effect of dexamethasone, a glucocorticoid extensively used in cancer therapies, on TRIMEL/DCs phenotype and immunogenicity was examined.ResultsDexamethasone induced a semi-mature phenotype on TRIMEL/DC with low maturation surface marker expressions, decreased pro-inflammatory cytokine induction (IL-1β and IL-12) and increased release of regulatory cytokines (IL-10 and TGF-β). Dexamethasone-treated TRIMEL/DCs inhibited allogeneic CD4⁺ T cell proliferation and cytokine release (IFNγ, TNF-α and IL-17). Co-culturing melanoma-specific memory tumor-infiltrating lymphocytes with dexamethasone-treated TRIMEL/DC inhibited proliferation and effector T cell activities, including cytokine secretion and anti-melanoma cytotoxicity.ConclusionsThese findings suggest that dexamethasone repressed melanoma cell lysate-mediated DC maturation, generating a potent tolerogenic-like DC phenotype that inhibited melanoma-specific effector T cell activities. These results suggest that dexamethasone-induced immunosuppression may interfere with the clinical efficacy of DC-based melanoma vaccines, and must be taken into account for optimal design of cellular therapy against cancer.     

Description of two new species of allocreadiid trematodes (Digenea: Allocreadiidae) in middle American freshwater fishes using an integrative taxonomy approach

Parasitology Research - Integrative taxonomy uses several sources of information to establish more robust species delimitation criteria. In this study, we followed that approach to describe two new...     

Taxonomic status of Rhabdochona ictaluri (Nematoda: Rhabdochonidae) based on molecular and morphological evidence

The genus Rhabdochona includes more than 100 species infecting freshwater fishes in all zoogeographical regions of the world. In Mexico, 12 nominal species of Rhabdochona have been recorded. Of these, Rhabdochona ictaluri was originally described as a parasite of endemic catfishes of the family Ictaluridae; however, the species was later considered on morphological grounds as a junior synonym of Rhabdochona kidderi. In this study, newly sampled specimens of R. ictaluri were obtained from the type host and type locality and were used to perform a detailed morphological analysis and molecular phylogenetic inferences through one mitochondrial and two nuclear genes; data were used in an integrative taxonomy context to test the taxonomic status of R. ictaluri. This approach proved to be very useful to confirm the validity of this species, and robust species limits were established between these two putative species considering morphology, molecular data, host association, and biogeography.

     

Characterization of metalloproteases and serine proteases of Toxoplasma gondii tachyzoites and their effect on epithelial cells

Parasitology Research - Toxoplasma gondii can infect all nucleated cells from warm-blooded organisms. After infection, Toxoplasma spreads throughout the body and migrates across biological...     

6,7-Dehydroroyleanone diterpene derived from Tetradenia riparia essential oil modulates IL-4/IL-12 release by macrophages that are infected with Leishmania amazonensis

Parasitology Research - The treatment of cutaneous leishmaniasis in associated with several adverse effects and therapeutic failure, resulting in patients’ abandonment of treatment. Research...     

Detection of “Candidatus Rickettsia wissemanii” in ticks parasitizing bats (Mammalia: Chiroptera) in the northern Brazilian Amazon

A total of 482 bats representing 32 species and two families were captured in the Amazon forests of the Amapá state in northern Brazil. Nineteen Artibeus planirostris bats (3.9 %) were infested with 160 ticks, all identified as Ornithodoros hasei. Three pools of larvae were screened for rickettsial DNA via polymerase chain reaction (PCR) targeting three rickettsial genes: gltA, ompA and htrA. Only one of them yielded an amplicons of the expected size for all three molecular assays. Comparisons of the obtained sequences including a phylogenetic analysis confirmed the occurrence of “Candidatus Rickettsia wissemanii” in Brazil.

     

HMGB1 decreases CCR-2 expression and migration of M2 macrophages under hypoxia

Inflammation Research - The hypoxic milieu at tumor microenvironment is able to drive the behavior of infiltrating tumor cells. Considering that hypoxia-mediated HMGB1 release is known to promote...