Multifunctional T cell response in convalescent patients two years after ZIKV infection

Interleukin 17 producing T cell responses in human chronic trichinellosis-insight from a case study

INTRODUCTION

We studied the cellular immune response in a patient infected since 10 months (along with other 51 people) during a trichinellosis outbreak caused by Trichinella spp.

METHODS

A 46 years old female resulted serologically positive for trichinellosis. We isolated peripheral blood mononuclear cells (PBMCs) and incubated them with excretory/secretory antigens (ESA) of Trichinella spiralis (T1) or Trichinella pseudospiralis (T4) to produce antigen specific T cell lines and clones, analysed for the phenotype (T helper or cytotoxic cells), for their T4 or T1 antigens specificity and for their cytokine profile (IFNγ, IL-17A, IL-4) by flow cytometry, thymidine incorporation assay and ELISpot.

RESULTS

The test performed using ESA from T1 or T4 has identified the species responsible for infection as T. pseudospiralis since the proliferative responses (evaluated by CFSE, Carboxyfluorescein succinimidyl ester, FACS analysis) was higher for T4 (72,8%) than T1 (23.6 %) antigen. The cell lines produced significant levels of IFNγ, IL-4 and IL-17A after stimulation. From the T cell line obtained in response to T1 ESA, as regards CD4 + cells, 12 % Th2, 22.8 % Th1, 6.6 % Th17, 6 % Th0, 2.2 % Th1/Th17 and 0.7 % Th2/Th17, were obtained. From the T1-specific TCL we generated 15 clones. From the TCL specific for T4 ESA, as regards CD4+, 15.2 % Th2, 27.1 % Th1, 3 % Th17, 10.3 %Th0, 1.9 % Th1/Th17 and 1 % Th2/ Th17 were obtained. From such TCL 4 clones were isolated, 1Th2, 1 Th1, 1 Th17, 1 Th1/Th17 and no Th0 nor Th2/Th17.

CONCLUSIONS

By cellular immunology techniques the species responsible of the infection resulted T. pseudospiralis, confirming the results previously obtained by serology. For the first time it was revealed in a human chronic infection the presence of Th17 cells.

PruΔcdpk2 Protects Pigs Against Acute Toxoplasmosis Depending on T-Lymphocyte Subsets and Natural Killer Cell Responses

Toxoplasma gondii is a widespread protozoan parasite approximately infecting one-third of the world population and can cause serious public health problems. In this study, we investigated the protective effect of the attenuated vaccine Pru:Δcdpk2 against acute toxoplasmosis and explored the underlying immune mechanisms of the protection in pigs. The systemic T-cell and natural killer (NK) cell responses were analyzed, including kinetics, phenotype, and multifunctionality (interferon [IFN]-γ, tumor necrosis factor [TNF]-α), and the IFN-γ levels were analyzed in PBMCs. Our results showed that T. gondii-specific antibodies were induced by Pru:Δcdpk2. After challenging with RH, the antibodies were able to respond quickly in the immunized group, and the expression level was significantly higher than that in the unimmunized group. The expression level of IFN-γ significantly increased after vaccination, and the CD3+ γδ-, NK, and CD3+ γδ+ cell subsets also significantly increased. At the same time, functional analysis indicated that these cells were polarized toward a Th1 phenotype, showing the ability to secrete IFN-γ and TNF-α. The CD4+CD8α-T cell population exhibited a higher frequency of IFN-γ+ producing cells compared with the CD4-CD8α+ and CD4+CD8α+ cell populations during the early days of vaccination. Our results indicated that the attenuated vaccine could induce the expression of NK, γδ, and CD3αβ cells in pigs, and IFN-γ and TNF-α secreted by these cells are important for resistance to T. gondii infection.

Peculiarities of Zika Immunity and Vaccine Development: Lessons from Dengue and the Contribution from Controlled Human Infection Model

The Zika virus (ZIKV) was first isolated from a rhesus macaque in the Zika forest of Uganda in 1947. Isolated cases were reported until 2007, when the first major outbreaks of Zika infection were reported from the Island of Yap in Micronesia and from French Polynesia in 2013. In 2015, ZIKV started to circulate in Latin America, and in 2016, ZIKV was considered by WHO to be a Public Health Emergency of International Concern due to cases of Congenital Zika Syndrome (CZS), a ZIKV-associated complication never observed before. After a peak of cases in 2016, the infection incidence dropped dramatically but still causes concern because of the associated microcephaly cases, especially in regions where the dengue virus (DENV) is endemic and co-circulates with ZIKV. A vaccine could be an important tool to mitigate CZS in endemic countries. However, the immunological relationship between ZIKV and other flaviviruses, especially DENV, and the low numbers of ZIKV infections are potential challenges for developing and testing a vaccine against ZIKV. Here, we discuss ZIKV vaccine development with the perspective of the immunological concerns implicated by DENV-ZIKV cross-reactivity and the use of a controlled human infection model (CHIM) as a tool to accelerate vaccine development.

Involvement of Th1Th17 Cell Subpopulations in the Immune Responses of Mothers Who Gave Birth to Children with Congenital Zika Syndrome (CZS)

High levels of T helper 17 cell (Th17)-related cytokines have been shown in acute Zika virus (ZIKV) infection. We hypothesized that the high levels of Th17-related cytokines, associated with a regulatory environment during pregnancy, create a favorable milieu for the differentiation of CD4+Th17 cells. We present data from a cross-sectional study on mothers who confirmed ZIKV infection by qRT-PCR and their children. We also recruited non-pregnant women infected with ZIKV in the same period. ZIKV infection occurred between 2015 and 2017. We collected samples for this study between 2018 and 2019, years after the initial infection. We highlight that, after in vitro stimulation with ZIKV CD4 megapool (ZIKV MP), we found a lower frequency of IL-17-producing CD4+ T cells (Th17), especially in the mothers, confirmed by the decrease in IL-17 production in the supernatant. However, a higher frequency of CD4+ IL-17+ IFN-γ+ T cells (Th1Th17) responding to the ZIKV MP was observed in the cells of the mothers and children but not in those of the non-pregnant women. Our data indicate that the priming of CD4 T cells of the Th1Th17 phenotype occurred preferentially in the mothers who gave birth to children with CZS and in the children.

Evaluation of the Expression of CCR5 and CX3CR1 Receptors and Correlation with the Functionality of T Cells in Women infected with ZIKV during Pregnancy

There have been reports of neurological abnormalities associated with the Zika virus (ZIKV), such as congenital Zika syndrome (CZS) in children born to mothers infected during pregnancy. We investigated how the immune response to ZIKV during pregnancy is primed and conduct a thorough evaluation of the inflammatory and cytotoxic profiles as well as the expression of CCR5 and CX3CR1. We compared the reactivity of T cells to ZIKV peptides in convalescent mothers infected during pregnancy. The child's clinical outcome (i.e., born with or without CZS) was taken to be the variable. The cells were stimulated in vitro with ZIKV peptides and evaluated using the ELISPOT and flow cytometry assays. After in vitro stimulation with ZIKV peptides, we observed a tendency toward a higher Interferon gamma (IFN-γ)-producing T cell responses in mothers who had asymptomatic children and a higher CD107a expression in T cells in mothers who had children with CZS. We found a higher frequency of T cells expressing CD107a+ and co-expressing CX3CR1+CCR5+, which is much clearer in the T cells of mothers who had CZS children. We suggest that this differential profile influenced the clinical outcome of babies. These data need to be further investigated, including the evaluation of other ZIKV peptides and markers and functional assays.