Anselmo Souza

Influence of HTLV-1 on the clinical, microbiologic and immunologic presentation of tuberculosis

BackgroundHTLV-1 is associated with increased susceptibility to Mycobacterium tuberculosis infection and severity of tuberculosis. Although previous studies have shown that HTLV-1 infected individuals have a low frequency of positive tuberculin skin test (TST) and decreasing in lymphoproliferative responses compared to HTLV-1 uninfected persons, these studies were not performed in individuals with history of tuberculosis or evidence of M. tuberculosis infection. Therefore the reasons why HTLV-1 infection increases susceptibility to infection and severity of tuberculosis are not understood.The aim of this study was to evaluate how HTLV-1 may influence the clinical, bacteriologic and immunologic presentation of tuberculosis.MethodsThe study prospectively enrolled and followed 13 new cases of tuberculosis associated with HTLV-1 (cases) and 25 patients with tuberculosis without HTLV-1 infection (controls). Clinical findings, bacterial load in the sputum, x-rays, immunological response and death were compared in the two groups.ResultsThere were no differences in the demographic, clinical and TST response between the two study groups. IFN-γ and TNF-α production was higher in unstimulated cultures of mononuclear cells of case than in control patients (p < 0.01). While there was no difference in IFN-γ production in PPD stimulated cultures, TNF-α levels were lower in cases than in controls (p = 0.01). There was no difference in the bacterial load among the groups but sputum smear microscopy results became negative faster in cases than in controls. Death only occurred in two co-infected patients.ConclusionWhile the increased susceptibility for tuberculosis infection in HTLV-1 infected subjects may be related to impairment in TNF-α production, the severity of tuberculosis in co-infected patients may be due to the enhancement of the Th1 inflammatory response, rather than in their decreased ability to control bacterial growth.

Functional Activity of Monocytes and Macrophages in HTLV-1 Infected Subjects

The Human T lymphotropic virus type-1 (HTLV-1) infects predominantly T cells, inducing proliferation and lymphocyte activation. Additionally, HTLV-1 infected subjects are more susceptible to other infections caused by other intracellular agents. Monocytes/macrophages are important cells in the defense against intracellular pathogens. Our aims were to determine the frequency of monocytes subsets, expression of co-stimulatory molecules in these cells and to evaluate microbicidal ability and cytokine and chemokine production by macrophages from HTLV-1 infected subjects. Participants were 23 HTLV-1 carriers (HC), 22 HAM/TSP patients and 22 healthy subjects (HS) not infected with HTLV-1. The frequencies of monocyte subsets and expression of co-stimulatory molecules were determined by flow cytometry. Macrophages were infected with L. braziliensis or stimulated with LPS. Microbicidal activity of macrophages was determined by optic microscopy. Cytokines/chemokines from macrophage supernatants were measured by ELISA. HAM/TSP patients showed an increase frequency of intermediate monocytes, but expression of co-stimulatory molecules was similar between the groups. Macrophages from HTLV-1 infected individuals were infected with L. braziliensis at the same ratio than macrophages from HS, and all the groups had the same ability to kill Leishmania parasites. However, macrophages from HTLV-1 infected subjects produced more CXCL9 and CCL5, and less IL-10 than cells from HS. While there was no correlation between IFN-γ and cytokine/chemokine production by macrophages, there was a correlation between proviral load and TNF and CXCL10. These data showed a dissociation between the inflammatory response and microbicidal ability of macrophages from HTLV-1 infected subjects. While macrophages ability to kill an intracellular pathogen did not differ among HTLV-1 infected subjects, these cells secreted high amount of chemokines even in unstimulated cultures. Moreover the increasing inflammatory activity of macrophages was similar in HAM/TSP patients and HC and it was related to HTLV-1 proviral load rather than the high IFN-γ production observed in these subjects.

Impairment of humoral and cellular immune response to tetanus toxoid in HTLV-1 infected individuals

The human T cell lymphotropic virus type-1 (HTLV-1) infect mainly T cells, dendritic cells and macrophages inducing T cell proliferation and increasing production of chemokines and cytokines by peripheral blood mononuclear cells (PBMC). However, as HTVL-1 may modify the immune response to other infectious agents, the aim of this study was to evaluate the humoral and cellular immune response before and after vaccination with tetanus toxoid (TT). Participants included 14 HTLV-1 carriers and 12 healthy subjects (HS). These individuals were immunized with two doses of tetanus toxoid vaccine. Antibodies to TT were determined by ELISA and the frequency of T cells expressing cytokines as well as the frequency of monocytes expressing co-stimulatory molecules were determined by FACS. The IgG titers anti-TT increased after immunization in both groups (p = 0.001), but HTLV-1 patients had lower levels of IgG anti-TT after immunization when compared with HS (p = 0.007). The frequency of CD4+ T cells expressing IFN-g, TNF and IL-10, after stimulation with TT, was lower in HTLV-1 infected subjects than the HS after immunization (p < 0.05). TNF and IL-12 expression by monocytes after stimulation with TT were higher in the HTLV-1 group than in HS. However there was an impairment in the HLA-DR expression by monocytes from HTLV-1 infected subjects. These results indicate that HTLV-1 infected subjects have a decreasing in humoral response and an impairment in both antigen presenting cells and T cell functions to a biased antigen. Financial Support: INCT-DT, CNPq, NIH R01.

Impaired TNF, IL-1β, and IL-17 production and increased susceptibility to Mycobacterium tuberculosis infection in HTLV-1 infected individuals

IFN-γ and TNF play critical roles in the control of Mycobacterium tuberculosis infection. Despite leading to an exaggerated production of inflammatory cytokines, HTLV-1 infection increases the risk of developing tuberculosis (TB). However, the immune mechanisms accounting for this phenomenon are still unclear. The aim of this study was to evaluate immunological aspects of the HTLV-1/M. tuberculosis co-infection. In this cross-sectional study, the levels of TNF, IL-1β, and IL-17 were determined by ELISA in the supernatants of either unstimulated or tuberculin purified protein derivative (PPD) stimulated peripheral blood mononuclear cells. Cells from HTLV-1 infected individuals produced lower levels of TNF following PPD stimulation compared to unstimulated cells. IL-1β and IL-17 production by cells from HTLV-1/M. tuberculosis co-infected individuals was lower than in cells from patients with TB. Impairment in TNF, IL-1β, and IL-17 production upon stimulation with mycobacterial antigens may contribute to the increased susceptibility to M. tuberculosis infection observed in HTLV-1 infected individuals.

HTLV-1 infection interferes with immune responses to Mycobacterium tuberculosis antigens

Tuberculosis (TB) is still a major health problem. IFN-γ and TNF are critical cytokines in the control of Mycobacterium tuberculosis (Mtb) infection. It has already been demonstrated that human T cell lymphotropic virus type 1 (HTLV-1) infection leads to a spontaneous IFN- γ and TNF production, however HTLV-1 infected subjects possess a 2-4 fold increased risk of developing tuberculosis. Nevertheless, the immune mechanisms involved in this phenomenon are still unclear. The aim of this study was to evaluate immunological features of the association between HTLV-1/Mtb in order to better understand the events leading to higher susceptibility to TB observed in HTLV-1 infected subjects. This was a cross-sectional study evaluating four groups: healthy control (HC group), HTLV-1 infected subjects without TB (HTLV-1 group) or with TB (HTLV-1 + TB group), and individuals with only TB (TB group). TNF, IL-1β, and IL-17 levels were measured in supernatants of non-stimulated or PPD stimulated peripheral blood mononuclear cells (PBMCs) by ELISA. PBMCs from HTLV-1 infected individuals had a decrease (p<0.05) in TNF production following PPD stimulation (median 114.5 pg/ml, IQ range 47-189 pg/ml) compared to non-stimulated cells (202 pg/ml, IQ range 100-250 pg/ml). When we normalized the data to non-stimulated cells, IL-1β production following PPD stimulation by individuals in the HTLV-1 + TB group (3 pg/ml, IQ range 0-43 pg/ml) was lower (p<0.05) than in patients with TB (87 pg/ml, IQ range 14-151 pg/ml). Similarly, HTLV-1/Mtb co-infected individuals had lower (p<0.05) production of IL-17 (9 pg/ml, IQ range 0-41 pg/ml) when compared to TB patients (43 pg/ml, IQ range 13-150 pg/ml). Impairment in TNF, IL-1β, and IL-17 production upon stimulation with mycobacterial antigens may contribute to the higher susceptibility to Mtb infection observed in HTLV-1 infected subjects. Financial support: CNPq, CAPES.

Clinical manifestations in HTLV-1 infected individuals without HAM/TSP: Results of an 8 years cohort

HTLV-1 is an endemic virus in the northeast of Brazil and is related to HAM/TSP in up to 5% of infected individuals. Despite this low prevalence it is known that a higher number of carriers presents with clinical and neurological symptoms that can be sensory, motor, urinary, inflammatory or autonomic.

Prevalence and influence of tuberculosis in the neurologic manifestations of the Human T cell lymphotropic virus type 1 (HTLV-1)

HTLV-1 infects mainly T cells, leading to activation and cellular proliferation with exaggerated production of pro-inflammatory cytokines. The majority of HTLV-1 infected patients are considered as HTLV-1 carriers, but 5% will develop HTLV-1 associated myelopathy (HAM) and about 15% overactive bladder, an oligosymptomatic form of HAM. HTLV-1 is associated with increased susceptibility to Mycobacterium tuberculosis infection but up to now it is unknown if HTLV-1 influences the severity of tuberculosis and if tuberculosis may influence the outcome of HTLV-1. The aims of this study were to determine the prevalence and severity of tuberculosis (TB) in HTLV-1 infected patients and analyze whether TB influences the outcome of HTLV-1 infection. This is a cross-sectional study, in which the prevalence of tuberculosis was analyzed in 166 HTLV-1 infected individuals. Cytokine productions were determined by ELISA, the proviral load was evaluated by PCR. Tuberculosis occurred in 33 (22%) of cases and 70 (42%) had a positive tuberculin skin test (TST) (latent tuberculosis). The majority of the cases did not have severe tuberculosis. There was no difference in the proviral load, but there was a higher frequency of HAM/TSP in the group with tuberculosis than in HTLV-1 infected subjects without TB (P<0.05). This study shows that the prevalence of M.tuberculosis infection is 6 fold higher in HTLV-1 infected individuals than that described in the Brazilian population the majority of co-infected had latent tuberculosis and HTLV-1 may influence progression from infection to HAM/TSP.

Local and systemic production of proinflammatory chemokines in the pathogenesis of HAM/TSP

BACKGROUND HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) is related with high proviral load, high proinflammatory cytokine levels, and passage of infected cell from the blood to the central nervous system. We aimed to evaluate the participation of chemokines and adhesion molecules in HAM/TSP pathogenesis. METHODS CXCL9, CXCL10, sICAM-1, and sVCAM-1 were determined by ELISA in serum and cerebrospinal fluid (CSF) of HTLV-1 infected individuals. The frequency and median fluorescence intensity (MFI) of lymphocytes and monocytes expressing ligands of adhesion molecules (CD11a and CD49d) and a chemokine receptor (CXCR3) were analyzed by flow cytometry. RESULTS The levels of CXCL9 and CXCL10 in serum of definite HAM/TSP were higher than in serum of probable HAM/TSP and HTLV-1 carriers. Considering the production of chemokines by patients with definite HAM/TSP, CXCL9 levels were higher in serum than in CSF, and CXCL10 production was higher in CSF than in serum. Levels of adhesion molecules in serum and CSF of HTLV-1 infected individuals did not differ. The MFI of CD11a on CD4+, CD8+ and CD14+ cells was lower in definite HAM/TSP than in HTLV-1 carriers and did not differ from probable HAM/TSP and healthy subjects (HS). The frequency of lymphocytes expressing CXCR3 was lower in definite HAM/TSP than in cells of probable HAM/TSP and did not differ from carrier and HS. CONCLUSION These data point to the participation of proinflammatory chemokines, especially CXCL10, in the pathogenesis of definite HAM/TSP.

Consequences of the association between HTLV-1 and tuberculosis

HTLV-1 modifies the immune response and clinical presentation of bacterial, fungal and helminthic infections. There are also evidences that helminthic infections may modify disease expression related to HTLV-1, increasing the occurrence of Adult T cell leukemia (ATL) and decreasing the development of HTLV-1 associated myelopathy or tropical spastic paraparesis (HAM/TSP). Recently it has been shown that HTLV-1 increases susceptibility for tuberculosis (TB) but the consequences of this co-infection in the clinical course of TB and HTLV-1 infection is not so clear. The aim of this study was to evaluate if TB influences neurologic disease in HTLV-1 infected subjects and to evaluate sequels of TB in HTLV-1 infected individuals. This is a nested case control study with the participation of 32 patients with previous diagnosis of TB and positivity sorology for HTLV-1 and 32 controls with HTLV-1 without TB paired by age, gender and time of admission in the clinic. Of the 32 patients with TB 29 had pulmonary TB, one had pleural TB, one laryngeal TB and the other lymphonode TB. Only 2 (6,2%) developed a second episode of TB. Among those who have been treated for TB 8 (25%) patients complained of dyspnea, 3 without evidence of pulmonary disease, 3 cases had chronic obstructive pulmonary disease (COPD) and two cases had bronchial overactivity. Regarding HTLV-1 associated disease probable HAM/TSP was diagnosed in 4 (12,5%) of the TB patients and in 6 (18,7%) of the patients who only have HTLV-1 infection (P > 0.05). Definitive HAM/TSP was diagnosed in 10 (31,2%) of the co-infected patients with HTLV-1 and TB and in 4 (12,5%) in the group who only had HTLV-1 (P < 0.05). While HTLV-1 appears to not influence the severity of Micobacterium tuberculosis infection TB was highly associated with HAM/TSP.

Neurological disability in HTLV-1 infected individuals according to the initial clinical presentation: cohort study

Background It’s estimated that 10 to 20 million people are infected with the HTLV-1 virus worldwide. Two principal diseases are associated with this virus: the Adult T-cell Lymphoma/Leukemia (ATLL), and the HTLV-1 Associated Myelopathy/ Tropical Spastic Paraparesis (HAM/ TSP). The last one is a debilitating neurological disease characterized by a chronic progressive paraparesis, with autonomic and mild sensorial complains. There are also incomplete forms of HAM/TSP, sometimes called subclinical or oligosymptomatic. Those mild and moderate neurological presentations are found in almost one fourth of the HTLV-1 patients and they include neurogenic bladder syndromes, erectile dysfunction, isolated pyramidal signs and peripheral neuropathy.