One of the types of external human parasites is a follicular scab called Demodex. Demodicosis is a skin disease in human and canine. Demodex mites feed on the epithelial cells of the hair follicle or sebaceous gland which found on and around the face. The host body immune system is responsible for controlling the population of parasites and Disruption of the cutaneous barrier causes stimulation of Toll-like receptors (TLRs) Consequently, Demodex chitin detect by keratinocyte TLRs. According to the results, association between Demodicosis and the HLA gene showed that individuals with the gene HLACW2 are five times more likely to develop Demodicosis than others because Nk2 and T1 cells of the adaptive immune response are reduced. In human Demodicosis, factors such as carbohydrate-like Tn antigen (expressed by Demodex) and secretion of pro-inflammatory mediators may play a role in the innate immune response. Additionally, the expression level of TLR2 was increased and TLR4, TLR6 expression was decreased. Flow cytometry analysis of blood samples collected from individuals with human Demodicosis and healthy individuals showed that in the patient group, there were more T9 and T reg cells in the blood samples and in skin homing T cell populations compared to the control group. Studies of canine Demodicosis have reported that lymphocyte populations are composed mostly of CD3+ and CD8+ T cells. The importance of the humoral immune response during primary Demodicosis has not yet been determined because no significant differences in circulatory immune were seen. It seems that the host immune system appears to recognize and tolerate the presence of these mites, although the physiological role of human Demodex mites in healthy skin remains unclear, especially the way in which they escape the innate immune system is very important.

Background: Cutaneous leishmaniasis (CL) is the most common clinical form of leishmaniasis that causes skin disease. Currently, there is no licensed prophylactic vaccine for CL, as the mechanisms of healing and memory T-cell responses that develop after infection with CL are far from fully understood. A review of the published articles identifying CL vaccine candidates, immuno-dominant antigens, and potent vaccine adjuvants is needed to provide comprehensive information. Therefore, we aimed to review vaccine candidates, immuno-dominant antigens, and potent vaccine adjuvants for preventing cutaneous leishmaniasis. Methods: A systematic search of published studies before December 2023 was identified using electronic databases; PubMed/MEDLINE, Hinari Research4Life, Google Scholar, and direct Google search. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Data were extracted using a Microsoft Excel 2010 spreadsheet and data obtained were then reported using tables and figures and synthesized qualitatively. The quality of the included studies was assessed using the Joanna Briggs Institute’s (JBI) quality appraisal tool for experimental studies. Results: The electronic databases search yielded 661 articles of which 32 articles met the inclusion criteria. The included articles were conducted in various animal and human models and included vaccine candidates, immuno-dominant antigens, and potent vaccine adjuvants. Some of the first-generation vaccine candidates showed complete protection of the specified animal model. They induced strong T-cell mediated and antibody-mediated humoral immune responses (e.g. Curdlan dectin-1, total Leishmania antigen (TLA), and L. infantum heat shock proteins ( LiΔHSP70-II)). Almost all second and third-generation vaccine candidates, and the immuno-dominant antigens of the parasite and the host enhance T cell-mediated and antibody-mediated immune responses. We also reviewed potent vaccine adjuvants such as myrrh silver nanoparticles (MSNPs), and Imiquimod, which play an important role in enhancing immune responses against Leishmania antigens. Conclusion and recommendations: The T-cell mediated immune response was significantly induced in various experimental models (e.g. IFN-γ and TNF-α response) and also the humoral arm in some instances (e.g. IgG2). This review thus provides comprehensive information on the efficacy and induction of protective immunity of vaccine candidates, antigenic molecules, and vaccine adjuvants against CL. However, there is still a need for a comprehensive understanding of the immuno-pathogenesis of the disease upon vaccination.

Co-evolutionary adaptation of hookworms with their mammalian hosts has selected for immunoregulatory excretory/secretory (E/S) products. However, it is not known whether, or if so, how host immunological status impacts the secreted profile of hematophagous adult worms. This study interrogated the impact of host Signal and transducer of activator of transcription 6 (STAT6) expression during experimental evolution of hookworms through sequential passage of the life-cycle in either STAT6 deficient or WT C57BL/6 mice. Proteomic analysis of E/S products by LC-MS showed increased abundance of 15 proteins, including myosin-3, related to muscle function, and aconitate hydratase, related to iron homeostasis. However, most E/S proteins (174 of 337 unique identities) were decreased, including those in the Ancylostoma-secreted protein (ASP) category, and metallopeptidases. Several identified proteins are established immune-modulators such as fatty acid-binding protein homolog, cystatin, and acetylcholinesterase. Enrichment analysis of InterPro functional categories showed down-regulation of Cysteine-rich secretory proteins, Antigen 5, and Pathogenesis-related 1 proteins (CAP), Astacin-like metallopeptidase, Glycoside hydrolase, and Transthyretin-like protein groups in STAT6 KO adapted worms. Taken together, these data indicate that in an environment lacking Type 2 immunity, hookworms alter their secretome by reducing immune evasion proteins- and increasing locomotor- and feeding-associated proteins.

Aim: Natural transmission of Trypanosoma cruzi occurs when infected hematophagous deposit feces contaminated with metacyclic trypomastigotes on injured skin or mucosa. To study the inflammatory response at the inoculation site, dissemination of parasites, Th cell subtypes at the local lymph nodes and myocarditis mice were exposed to Triatoma dimidiata naturally contaminated with Trypanosoma cruzi. Methods and results: Mice were intradermal inoculated with T. dimidiata feces containing metacyclic trypomastigotes or were previously immunized with feces without metacyclic trypomastigotes and analyzed from 15 minutes to 3 months after inoculation. Parasites remained at the inoculation site until 20 days after inoculation but disappeared early in pre-immunized mice that presented with edema and collagen fragmentation as early as 15 minutes after being challenged with metacyclic trypomastigotes. The Th2 subpopulation dominated in the first week in mice infected with feces containing metacyclic trypomastigotes, whereas Th1 and Th17 populations dominated in the challenged mice population. Similarly in heart tissue, intense myocarditis and remodeling, with faster clearance of amastigotes was observed in mice previously immunized with Triatoma dimidiata feces. Furthermore, immune cell-types, Th1 and Th17, predominated after 20 days post-infection in all experimental groups. Conclusions: Previous exposure with Triatoma dimidiata feces prior to infection with metacyclic trypomastigotes favors parasitic dissemination and early induction of Th1 and Th17 subpopulations with lower parasitism in heart tissue but does not ameliorate inflammation and tissue damage which is accompanied with Th1/Th17 and Treg profile.

Introduction: The T-cell subset (CD4+Tregs) play a significant role in immunoregulation, by active suppression of the immune system, through cell-to-cell contact and the secretion of IL10. The frequencies of these cell subpopulations were investigated in the mother. Methods: The study recruited 61 mothers out of this number, 31 mothers with plasmodium parasitized placentas and 30 mothers without plasmodium infection. Placental malaria positivity was determined by PCR and microscopy. Peripheral mononuclear cells (PBMCs) were isolated from peripheral blood, cultured in the presence of VAR2CSA antigen, and stained with antibodies (CD3, CD4, CD25, and IL-10), before cytometry analysis. Results: The CD4+CD25+ T cell frequencies were significantly higher in all the participants (p<0.0001), and comparable across gravida. These cell populations were similar when compared between primigravid and secumgravida mothers (p=0.77), and between multigravida and secumgravida mothers (p=0.84). Primigravid mothers with placental malaria had significantly higher frequencies of CD4+CD25+ T cell population (p=0.04). The frequencies of CD4+IL10 were significantly high in both primigravid and multigravid mothers who were placental malaria positive (p=0.03) and (p=0.04) respectively. Conclusion: Induced Tregs (CD4+IL10) cells could play a role in placental malaria susceptibility due to an increase in their populations in mothers with plasmodium-infected placentas.