Increased Frequency of CD4 and CD8 Regulatory T Cells in Individuals under 15 Years with Multibacillary Leprosy

Abstract

BackgroundLeprosy is a chronic disease, caused by Mycobacterium leprae, which poses a serious public health problem worldwide. Its high incidence in people under 15 years old in Ceará state, Brazil, reflects the difficulty of its control. The spectrum of clinical manifestations is associated with the immune response developed, with the Th1 and Th2 responses being related to the paucibacillary and multibacillary forms, respectively. Regulatory T cells (Treg), which can suppress Th1 and Th2 response, have received special attention in the literature and have been associated with development of chronic infections. However, their role in leprosy in individuals under 15 years old has not yet been elucidated. We evaluated the frequency of CD4+/CD8+CD25highFOXP3+ and CD4+/CD8+CD25highFOXP3high cells in leprosy patients and household contacts, in both cases under 15 years old.Methodology/Principal FindingsPBMC from 12 patients and 17 contacts were cultured for 72 hours with anti-CD3 and anti-CD28 (activators) or with activators associated with total sonicated fraction of M. leprae. After culture, the frequency of CD4+/CD8+ Treg was identified by flow cytometry. Cells stimulated by activators and antigen from multibacillary patients showed Treg frequencies almost two times that of the contacts: CD4+FOXP3+ (21.93±8.43 vs. 13.79±8.19%, p = 0.0500), CD4+FOXP3high (10.33±5.69 vs. 5.57±4.03%, p = 0.0362), CD8+FOXP3+ (13.88±9.19 vs. 6.18±5.56%, p = 0.0230) and CD8+FOXP3high (5.36±4.17 vs. 2.23±2.68%, p = 0.0461). Furthermore, the mean fluorescence intensity of FOXP3 in Treg was higher in multibacillary patients than in the contacts. Interestingly, there was a positive correlation of the bacillary index and number of lesions with the frequency of all Treg evaluated in patients.Conclusions/SignificanceWe have demonstrated for the first time that multibacillary leprosy patients under 15 years old have greater CD4+ and CD8+ Treg frequencies and these correlate with clinical and laboratorial aspects of disease. These findings suggest the involvement of these cells in the perpetuation of M. leprae infection.

Development of Type 2, But Not Type 1, Leprosy Reactions is Associated with a Severe Reduction of Circulating and In situ Regulatory T-Cells

“…CD8+ Tregs have recently been shown to be augmented after in vitro stimulation in children with MB leprosy compared with age-matched contacts. 21 As illustrated in Figure 1A, the presence of CD25+ or CD25+ high cells within the CD8 subset (the TCD3+ CD4…”

Serum Th1/Th2 and macrophage lineage cytokines in leprosy; correlation with circulating CD4+CD25highFoxP3+ T‐regs cells

“…Saini et al (44) reported increased TGF-b secreting CD4⁺CD25⁺ FoxP3⁺ T-regs in anergic LL patients in both skin lesions and M. leprae stimulated PBMC cultures. Likewise, Fernandes et al (45) demonstrated that MB leprosy patients under 15 years old have greater CD4⁺ FoxP3⁺ T-regs frequencies after stimulated PBMC cultures. The discrepancies between these findings and ours could be due to different techniques of assay as well as different sites, for example lesional assay.…”

“…Likewise, Fernandes et al. demonstrated that MB leprosy patients under 15 years old have greater CD4⁺ FoxP3⁺ T‐regs frequencies after stimulated PBMC cultures. The discrepancies between these findings and ours could be due to different techniques of assay as well as different sites, for example lesional assay.…”

Regulatory T-Cells at the Interface between Human Host and Pathogens in Infectious Diseases and Vaccination

“…In T-cells isolated from LL patients, Foxp3 interacted with histone deacetylases and bound directly to the promotor regions of CD25 and CTLA-4 ( 90 ). The importance of this transcriptional regulation by Foxp3 within the immunological spectrum of disease is further supported by the fact that not only Treg frequencies are increased in LL compared to BT patients but also the intensity of expression (mean fluorescence intensity) of Foxp3 as determined by flow cytometry ( 83 ).…”

“…Though the exact mechanisms ruling this spectrum have not been elucidated, it is clear that Tregs play a part, and demonstration of the suppressive activity of CD4 + and CD8 + Tregs isolated from the skin and circulation of LL patients were among the first reports on “human T-suppressor cells” ( 6 , 7 ). In the circulation of leprosy patients, both CD4 + Foxp3 + and CD8 + Foxp3 + T-cells were almost twofold increased compared to healthy contacts ( 83 ). Within the spectrum of disease, increased percentages of CD4 + Foxp3 + CD25 + and CD8 + Foxp3 + CD25 + T-cells have been demonstrated in the circulation of LL patients compared to BT patients or healthy contacts ( 82 , 84 ).…”