Presence of Senescent and Memory CD8+ Leukocytes as Immunocenescence Markers in Skin Lesions of Elderly Leprosy Patients.

Leprosy is an infectious disease that remains endemic in approximately 100 developing countries, where about 200,000 new cases are diagnosed each year. Moreover, multibacillary leprosy, the most contagious form of the disease, has been detected at continuously higher rates among Brazilian elderly people. Due to the so-called immunosenescence, characterized by several alterations in the quality of the immune response during aging, this group is more susceptible to infectious diseases. In view of such data, the purpose of our work was to investigate if age-related alterations in the immune response could influence the pathogenesis of leprosy. As such, we studied 87 individuals, 62 newly diagnosed and untreated leprosy patients distributed according to the age range and to the clinical forms of the disease and 25 healthy volunteers, who were studied as controls. The frequency of senescent and memory CD8+ leukocytes was assessed by immunofluorescence of biopsies from cutaneous lesions, while the serum levels of IgG anti-CMV antibodies were analyzed by chemiluminescence and the gene expression of T cell receptors' inhibitors by RT-qPCR. We noted an accumulation of memory CD8+ T lymphocytes, as well as reduced CD8+CD28+ cell expression in skin lesions from elderly patients, when compared to younger people. Alterations in LAG3 and PDCD1 gene expression in cutaneous lesions of young MB patients were also observed, when compared to elderly patients. Such data suggest that the age-related alterations of T lymphocyte subsets can facilitate the onset of leprosy in elderly patients, not to mention other chronic inflammatory diseases.

Increased oxidative stress in elderly leprosy patients is related to age but not to bacillary load.

BACKGROUND: Leprosy continues to be a public health problem in Brazil. Furthermore, detection rates in elderly people have increased, particularly those of multibacillary (L-Lep) patients, who are responsible for transmitting M. leprae. Part of the decline in physiological function during aging is due to increased oxidative damage and change in T cell subpopulations, which are critical in defense against the disease. It is not still clear how age-related changes like those related to oxidation affect elderly people with leprosy. The aim of this work was to verify whether the elderly leprosy patients have higher ROS production and how it can impact the evolution of leprosy. METHODOLOGY/PRINCIPAL FINDINGS: 87 leprosy patients, grouped according to age range and clinical form of leprosy, and 25 healthy volunteers were analyzed. Gene expression analysis of antioxidant and oxidative burst enzymes were performed in whole blood using Biomark's microfluidic-based qPCR. The same genes were evaluated in skin lesion samples by RT-qPCR. The presence of oxidative damage markers (carbonylated proteins and 4-hydroxynonenal) was analyzed by a DNPH colorimetric assay and immunofluorescence. Carbonylated protein content was significantly higher in elderly compared to young patients. One year after multidrug therapy (MDT) discharge and M. leprae clearance, oxidative damage increased in young L-Lep patients but not in elderly ones. Both elderly T and L-Lep patients present higher 4-HNE in cutaneous lesions than the young, mainly surrounding memory CD8+ T cells. Furthermore, young L-Lep demonstrated greater ability to neutralize ROS compared to elderly L-Lep patients, who presented lower gene expression of antioxidant enzymes, mainly glutathione peroxidase. CONCLUSIONS/SIGNIFICANCE: We conclude that elderly patients present exacerbated oxidative damage both in blood and in skin lesions and that age-related changes can be an important factor in leprosy immunopathogenesis. Ultimately, elderly patients could benefit from co-supplementation of antioxidants concomitant to MDT, to avoid worsening of the disease.

Role of TEFFECTOR/MEMORY Cells, TBX21 Gene Expression and T-Cell Homing Receptor on Type 1 Reaction in Borderline Lepromatous Leprosy Patients.

In spite of hyporesponsivity to Mycobacterium leprae, borderline lepromatous (BL) patients show clinical and immunological instability, and undergo frequent acute inflammatory episodes such as type 1 reaction (T1R), which may cause nerve damages. This work focused on the participation of T cell subsets from blood and skin at T1R onset. We observed a significantly increased ex vivo frequency of both effector and memory CD4+ and CD8+ T cells in T1R group. Besides, ex vivo frequency of T cell homing receptor, the Cutaneous Leukocyte-associated Antigen (CLA) was significantly increased in T cells from T1R patients. M. leprae induced a higher frequency of CD4+ TEM and CD8+ TEF cells, as well as of CD8+/TEMRA (terminally differentiated effector T cells) subset, which expressed high CD69+. The presence of IFN-γ‒producing-CD4+ TEF and naïve and effector CD8+ T lymphocytes was significant in T1R. TBX21 expression was significantly higher in T1R, while BL showed increased GATA3 and FOXP3 expression. In T1R, TBX21 expression was strongly correlated with CD8+/IFN-γ‒ T cells frequency. The number of double positive CD8+/CLA+ and CD45RA+/CLA+ cells was significantly higher in skin lesions from T1R, in comparison with non-reactional BL group. The observed increase of ex vivo T cells at T1R onset suggests intravascular activation at the beginning of reactional episodes. The antigen-specific response in T1R group confirmed the higher number of CD8+/CLA+ and CD45RA+/CLA+ cells in T1R lesions suggests possible migration of these cells activated by M. leprae components inside the vascular compartment to skin and participation in T1R physiopathology.