Griselda Didoli

Protected Trypanosoma cruzi infection in rats born to mothers receiving interferon-gamma during gestation is associated with a decreased intramacrophage parasite growth and preferential synthesis of specific IgG2b antibodies

We demonstrated that administration of interferon gamma (IFN-gamma) to pregnant rats conferred partial resistance in their offspring to further challenge with Trypanosoma cruzi. Because of the effects of IFN-gamma on macrophage activation and immunoglobulin isotype selection, offspring were now studied to ascertain whether this intervention modifies the in vitro replication of T. cruzi and nitric oxide (NO) production by peritoneal macrophages (PE), together with the anti-T. cruzi IgG isotypes. To evaluate the possibility of a detrimental effect of IFN-gamma, serum levels of anti-sulphatide autoantibodies were also investigated. Offspring were born to mothers undergoing one of the following procedures during gestation: treatment with recombinant rat IFN-gamma, 50,000 IU/rat, five times/week for 3 weeks, which was started on the day of mating; infection with 10(6) trypomastigotes of T. cruzi at 7, 14, and 21 days after mating plus IFN-gamma treatment as given to the former group; the same protocol except that physiological saline was injected instead of IFN-gamma; injection of physiological saline only. Offspring were challenged at weaning with a similar dose of T. cruzi, to constitute four groups of infected young, plus an additional group of age-matched uninfected rats born to control mothers. PE were harvested at day 7 postinfection (pi), exposed to parasites and further investigated for the replication of T. cruzi and NO production, whereas ELISA studies for measuring serum anti-T. cruzi IgG subclasses and anti-sulphatide autoantibodies were performed at day 30 pi. The number of intracellular parasites in PE was markedly decreased in young born to IFN-gamma-treated mothers, this not being accompanied by higher nitrite levels in culture supernatants. Offspring delivered by IFN-gamma-treated mothers showed no higher serum concentrations of anti-sulphatide autoantibodies, but exhibited a preferential synthesis of anti-T. cruzi IgG2b antibodies. This rat isotype is known to fix complement and constitutes the rat counterpart of IgG2a mouse immunoglobulins whose synthesis is favoured by IFN-gamma.

The Adrenal Steroid Response during Tuberculosis and Its Effects on the Mycobacterial-driven IFN-γ Production of Patients and Their Household Contacts

Earlier studies revealed that patients with tuberculosis (TB) have imbalanced immunoendocrine responses and that adrenal steroids [cortisol and dehydroepiandrosterone (DHEA)] can modify their specific cell‐mediated immune response. Because most household contacts (HHCs) of contagious TB patients develop a subclinical and self‐controlled process (latent TB), we studied some features of their immune and endocrine responses, particularly those related to the hypothalamic–pituitary–adrenal axis. Nineteen HHCs, 24 untreated TB patients (15 moderate, 9 advanced), and 18 healthy controls of similar age were studied. Patients had increased and reduced levels of cortisol and DHEA, respectively. DHEA levels were also reduced in HHCs. Stimulation of peripheral blood mononuclear cells (PBMC) with Mycobacterium tuberculosis sonicate resulted in increased in vitro lymphoproliferation in HHCs, while advanced patients showed the lowest response. Significantly higher amounts of interferon (IFN)‐γ were detected in supernatants from stimulated PBMC of HHCs when compared to controls and TB patients. Addition of cortisol to the cultures inhibited mycobacterial antigen‐driven IFN‐γ production in all groups, although HHC supernatant contained significantly higher concentrations. In contrast, addition of DHEA to cultures of cells from HHCs resulted in increased IFN‐γ levels. These results suggest the existence of a particular immunoendocrine relation assuring a preserved IFN‐γ production in healthy housemates of TB patients.

Increased frequency of CD4+ CD25+ FoxP3+ T regulatory cells in pulmonary tuberculosis patients undergoing specific treatment and its relationship with their immune-endocrine profile.

Tuberculosis (TB) is a major health problem requiring an appropriate cell immune response (IR) to be controlled. Since regulatory T cells (Tregs) are relevant in IR regulation, we analyzed Tregs variations throughout the course of TB treatment and its relationship with changes in immune-endocrine mediators dealing with disease immunopathology. The cohort was composed of 41 adult patients, 20 of them completing treatment and follow-up. Patients were bled at diagnosis (T0) and at 2 (T2), 4 (T4), 6 (T6), and 9 months following treatment initiation. Twenty-four age- and sex-matched healthy controls (HCo) were also included. Tregs (flow cytometry) from TB patients were increased at T0 (versus HCo P < 0.05), showing even higher values at T2 (versus T0 P < 0.01) and T4 (versus T0 P < 0.001). While IL-6, IFN-γ, TGF-β (ELISA), and Cortisol (electrochemiluminescence, EQ) were augmented, DHEA-S (EQ) levels were diminished at T0 with respect to HCo, with cytokines and Cortisol returning to normal values at T9. Tregs correlated positively with IFN-γ (R = 0.868, P < 0.05) at T2 and negatively at T4 (R = −0.795, P < 0.05). Lowered levels of proinflammatory cytokines together with an increased frequency of Tregs of patients undergoing specific treatment might reflect a downmodulatory effect of these cells on the accompanying inflammation.

Maternal immunization with actinomycetales immunomodulators reduces parasitemias in offspring challenged with Trypanosoma cruzi

This article describes the first use of heat-killed, borate-buffered preparations of aerobic actinomycetales to immunize pregnant animals in order to determine the effect on their pregnancy and fertility and the survival coefficients of their offspring. Pregnant rats received three injections of Gordonia bronchialis, Rhodococcus coprophylus or physiological saline and a proportion of their offspring were challenged with live Trypanosoma cruzi at the time of weaning. Levels of parasitemia and, in some animals, of the cytokines IFN-γ and IL-10 were measured. The progress of pregnancy, fertility and survival of offspring were unaffected by the maternal immunizations. The offspring of rats immunized with G. bronchialis displayed significantly reduced parasitemias, with increased levels of IFN-γ and reduced levels of IL-10, 4 days after challenge. The offspring of rats immunized with R. coprophylus displayed greater parasitemias than did those of the control group. These unexpected results are discussed and their causation considered.

mRNA expression of alpha and beta isoforms of glucocorticoid receptor in peripheral blood mononuclear cells of patients with tuberculosis and its relation with components of the immunoendocrine response.

We have analyzed the expression of glucocorticoid receptor (GR) isoforms by real time RT-qPCR in PBMCs from 19 controls (HCo) and 28 TB patients (8 mild; 12 moderate; 8 severe), HIV(-) and similar sex and age distribution. mRNA hGRα/β ratios were found higher in TB patients respect to those in HCo. However, when analyzing for disease severity such overall trend was at the expense of mild and moderate patients, with severe cases showing a lower mRNA hGRα/β ratio with respect to the other patient groups. This suggested some degree of resistance to endogenous glucocorticoids in patients with severe TB, since hGRαα dimer mediates the biological functions of GC, with the GRβ isoform acting as an inhibitor of GC activity. Levels of IL-6, IL-18, IFN-γ and Cortisol were significantly increased in severe and moderate cases, whereas DHEA values were found decreased in them (p<0.05 respect to HCo). Analysis on the relationship between plasma levels of these immuno-endocrine mediators with the mRNA expression of hGRα and hGRβ showed that IL-6 was positively associated with hGRα in mild TB patients (p<0.01), whereas a negative correlation between IFN-γ and hGRβ was observed in severe cases (p<0.01). As regard to hormones, DHEA was positively associated with hGRα in moderate and severe cases (p<0.01). This group also showed a negative correlation between hGRα and Cortisol/DHEA ratios (p<0.05). Changes in the systemic levels of cytokine and adrenal hormones are likely to affect GR expression in a differential fashion and according to the amount of pulmonary involvement.

Chronic Trypanosoma cruzi infection in the rat: Cyclophosphamide-induced recovery of adjuvant arthritis correlates with changes in the levels of lymph node T-lymphocytes and class II+ cells

We have previously reported that treatment with cyclophosphamide (Cy) reversed the partial resistance of chronically Trypanosoma cruzi-infected rats to adjuvant-induced arthritis (AA) and caused a slight enhancement of arthritis in controls, when given 48 h before induction. To ascertain whether this Cy effect could be associated with regional changes of immunocompetent cells, popliteal lymph nodes were studied for their T-cell subsets and cells carrying class II major histocompatibility (MHC) antigens (1-A and 1-E molecules). Analysis at the time of arthritis induction revealed that infected rats receiving Cy 48 h earlier appeared to have recovered from the inverse balance of major T-cell subsets and showed 1-E+ cells lowered to normal, whereas values from control rats remained unchanged by Cy treatment. Establishment of AA was associated with substantial changes in the phenotype of lymph node cells that drained the affected limb. Changes were equally recorded in control and infected arthritic rats, and consisted of a significant raise of CD4+ and I-A+ cells along with lowered numbers of CD8+ and I-E+ cells. Treatment with Cy lowered even further the levels of CD8+ cells, while causing no affectation in the number of CD4+ cells that remained increased as in the arthritic counterparts receiving no Cy. Comparative analysis of class II MHC+ cells in Cy-treated rats revealed an additional decrease of I-E+ cells in draining lymph nodes from infected and control rats, which coincided with a simultaneous increase in I-A+ cells in the uninfected group. It is suggested that a deletion of a regulatory T-cell subset as well as an improved presentation of arthritogenic peptides may at least underlie the Cy-induced enhancement of the arthritic response.