Molecular and biochemical parasitology最新文献

The scabies mite is known to induce a complicated immune response that involves both innate and long-term adaptive immunity. Many immune effectors and pathways are involved. Th17/Treg balance can influence the complex immune response to scabies. The immunological effectors including IL-17A, as a pro-inflammatory cytokine, and Treg cells, anti-inflammatory regulatory T cells, are essential for preserving cutaneous immunological homeostasis. So, evaluating these immune effectors may help in comprehending the pathophysiology of scabies and facilitate the development of new treatment approaches. This study examined the expression of IL-17A and FoxP3⁺ in the skin and serum of 50 scabies patients and 25 healthy controls. An assessment of their correlation with clinical features was performed. Regarding tissue response, scabietic patients exhibited a significant increase in IL-17A and FoxP3⁺ expression in their epidermis and dermis compared to controls (P<0.001), but the correlation between these factors was not significant in either area (P>0.05). Also, patients showed a significant increase in serum IL-17A levels compared to controls (P<0.001), with a significant association between serum IL-17A levels and lesion severity, but no significant correlation was observed between skin and serum responses (P>0.05). In conclusion, there was increased expression of both IL-17A and FoxP3⁺, with FoxP3⁺ being significantly more abundant than IL^-17A in the skin of scabies patients. Skin FoxP3⁺ up-regulation has been linked to the severity of the condition.

The Leishmania life cycle alternates between promastigotes, found in the sandfly, and amastigotes, found in mammals. When an infected sandfly bites a host, promastigotes are engulfed by phagocytes (i.e., neutrophils, dendritic cells, and macrophages) to establish infection. When these phagocytes die or break down, amastigotes must be re-internalized to survive within the acidic phagolysosome and establish disease. To define host kinase regulators of Leishmania promastigote and amastigote uptake and survival within macrophages, we performed an image-based kinase regression screen using a panel of 38 kinase inhibitors with unique yet overlapping kinase targets. We also targeted inert beads to complement receptor 3 (CR3) or Fcγ receptors (FcR) as controls by coating them with complement/C3bi or IgG respectively. Through this approach, we identified several putative host kinases that regulate receptor-mediated phagocytosis and/or the uptake of L. amazonensis. Findings included kinases previously implicated in Leishmania uptake (such as Src family kinases (SFK), Abl family kinases (ABL1/c-Abl, ABL2/Arg), and spleen tyrosine kinase (SYK)), but we also uncovered many novel kinases. Our methods also predicted host kinases necessary for promastigotes to convert to amastigotes or for amastigotes to survive within macrophages. Overall, our results suggest that the concerted action of multiple interconnected networks of host kinases are needed over the course of Leishmania infection, and that the kinases required for the parasite’s life cycle may differ substantially depending on which receptors are bound and the life cycle stage that is internalized. In addition, using our screen, we identified kinases that appear to preferentially regulate the uptake of parasites over beads, indicating that the methods required for Leishmania to be internalized by macrophages may differ from generalized phagocytic mechanisms. Our findings are intended to be used as a hypothesis generation resource for the broader scientific community studying the roles of kinases in host-pathogen interactions.

Most protocols used to study the dynamics of calcium (Ca²⁺) in the malaria parasite are based on dyes, which are invasive and do not allow discrimination between the signal from the host cell and the parasite. To avoid this pitfall, we have generated a parasite line expressing the genetically encoded calcium sensor GCaMP3. The PfGCaMP3 parasite line is an innovative tool for studying spontaneous intracellular Ca²⁺ oscillations without external markers. Using this parasite line, we demonstrate the occurrence of spontaneous Ca²⁺ oscillations in the ring, trophozoite, and schizont stages in Plasmodium falciparum. Using the Fourier transform to fluorescence intensity data extracted from different experiments, we observe cytosolic Ca²⁺ fluctuations. These spontaneous cytosolic Ca²⁺ oscillations occur in the three intraerythrocytic stages of the parasite, with most oscillations occurring in the ring and trophozoite stages. A control parasite line expressing only a GFP control did not reveal such fluctuations, demonstrating the specificity of the observations. Our results clearly show dynamic, spontaneous Ca²⁺ oscillations during the asexual stage in P. falciparum, independent from external stimuli.

RNA interference (RNAi) on parasitic nematodes has been described as a valuable tool for screening putative targets that could be used as novel drug and/or vaccine candidates. This study aimed to set up a pipeline to identify potential targets using RNAi for vaccine/anti-parasite therapy development against Haemonchus contortus, a blood-feeding abomasal nematode parasite. The available H. contortus sequence data was mined for targets, which were tested for essentiality using RNAi electroporation assays. A total of 56 genes were identified and tested for knockdown using electroporation of first-stage larvae (L1) H. contortus with the target double-stranded RNA. Electroporation of L1 proved to be effective overall; 17 targets had a strong phenotype and significant reduction in alive H. contortus, and another 24 had a moderate phenotype with a significant reduction in larvae development. A total of 28 targets showed a significant reduction in the development of H. contortus larvae to the infective stage (L3) following the RNAi assay. Down-regulation of target transcript levels was evaluated in some targets by semi-quantitative PCR. Four out of five genes tested showed complete knockdown of mRNA levels via semi-quantitative PCR, whereas the knockdown was partial for one. In conclusion, the results indicate that the RNAi pathway is confirmed in H. contortus and that several target genes have the potential to be investigated further as possible vaccine candidates.