Mycobacterium tuberculosis Rv1419 encodes a secreted 13 kDa lectin with immunological reactivity during human tuberculosis

In this study, we have identified a secreted 13 kDa lectin from Mtb (Mtb, Mycobacterium tuberculosis; sMTL-13) by homology search of a non-redundant lectin database. Bioinformatic analysis revealed that sMTL-13 belongs to the ricin-type beta-trefoil family of proteins containing a Sec-type signal peptide present in Mtb complex species, but not in non-tuberculous mycobacteria. Following heterologous expression of sMTL-13 and generation of an mAb (clone 276.B7/IgG1kappa), we confirmed that this lectin is present in culture filtrate proteins from Mtb H37Rv, but not in non-tuberculous mycobacteria-derived culture filtrate proteins. In addition, sMTL-13 leads to an increased IFN-gamma production by PBMC from active tuberculosis (ATB) patients. Furthermore, sera from ATB patients displayed high titers of IgG Ab against sMTL-13, a response found to be decreased following successful anti-tuberculosis therapy. Together, our findings reveal a secreted 13 kDa ricin-like lectin from Mtb, which is immunologically recognized during ATB and could serve as a biomarker of disease treatment.

Correlation between interleukin-10 and in situ necrosis and fibrosis suggests a role for interleukin-10 in the resolution of the granulomatous response of tuberculous pleurisy patients

In order to identify mediators involved in immune-mediated disease regression, the pleural cytokine and histopathological profile was evaluated in tuberculous pleurisy patients with varied disease duration and clinical presentation, previous to chemotherapy. Interleukin (IL)-10, interferon (IFN)-gamma and tumor necrosis factor (TNF) levels in pleural fluids were shown to decrease with disease time. IL-10 was positively correlated with IFN-gamma, TNF and necrosis area in pleural sections. To parallel these findings with disease regression, individuals showing fever, anorexia, and progressive exudate in the pleural cavity (active disease) were compared with patients without symptoms and with a decrease in exudate volume (regressive disease). IFN-gamma and TNF levels were lower in regressive disease, as well as reduced necrosis area in pleural sections. Our results indicate that tissue destruction and a prominent Th1 response mark the early phase of tuberculous pleurisy and suggest that down-modulation of this response, with the possible participation of IL-10, is associated with disease resolution.

Relação entre comprimento craniocaudal e diâmetro da vesícula embrionária/fetal com idade de gestação por meio de avaliação ultra-sonográfica em ovino da raça Bergamácia

Este trabalho objetivou relacionar o diâmetro da vesícula embrionária/fetal (DVE) e comprimento craniocaudal do embrião/feto (CCC) do 15º ao 45º dia de gestação com a idade de gestação em ovelhas. Utilizaram-se 19 ovelhas adultas da raça Bergamácia, com cio sincronizado e cobertas por um mesmo reprodutor. A avaliação ultra-sonográfica foi realizada diariamente do 15º ao 30º dia após a cobrição e a cada cinco dias do 30º ao 45º dia, utilizando-se aparelho com transdutor linear de 5,0 e 7,5MHZ. O crescimento diário médio do DVE e CCC foi de 1,40mm e 1,33mm, respectivamente. A calibragem inversa obtida para DVE foi: Dias = -11 + 50(0,1 + 0,04log DVE)½, com R² = 0,85 e para CCC foi: Dias = 13,63 + 12,5(-0,71 + 0,16CCC)½, com R² = 0,93. Tanto o DVE como o CCC obtidos por ultra-sonografia são medidas pelas quais se pode prever a idade de gestação em ovelhas da raça Bergamácia.

Perfil dos constituintes do sangue no puerpério imediato de ovelhas submetidas a cesariana eletiva e de ovelhas com parto normal

Compararam-se os perfis dos constituintes do sangue de ovelhas submetidas a cesariana eletiva (n=21; GI) ou com partos normais (n= 11; GII). Obtiveram-se amostras de sangue em cinco momentos: no dia do parto, antes de sua ocorrência (M1), um (M2), dois (M3), três (M4) e sete (M5) dias pós-parto. Os valores do eritrograma em todos os animais apresentaram-se normais, não se constituindo em guia para o prognóstico da ocorrência pós-parto. No leucograma do GI observou-se presença de neutrófilos imaturos nos animais que morreram após a cirurgia. Apesar de a contagem de neutrófilos imaturos ter sido sugestiva do efeito da cesariana, nenhuma variável hematológica mensurada constituiu-se em acurado guia para o prognóstico da cesariana.

Cell-mediated immune responses and cytotoxicity to mycobacterial antigens in patients with tuberculous pleurisy in Brazil

Evaluating human immune response to defined Mycobacterium tuberculosis antigens in patients with different clinical forms of tuberculosis may help in elucidating pathogenesis and in vaccine development. In the present report we evaluated the lymphocyte proliferation, cytokine production and natural killer cell cytotoxicity as parameters to screen four mycobacterial recombinant antigens. Pleural fluid mononuclear cells (PFMC) and peripheral blood mononuclear cells (PBMC) from 13 HIV-negative patients with tuberculous pleurisy, living in a tropical region of Brazil were used in these assays. Crude M. tuberculosis antigen and recombinant 70-, 65- and 38-kDa mycobacterial antigens, induced greater proliferation in PFMC than in PBMC. IFN-gamma, TNF-alpha, IL-4 and IL-10 were evaluated in the PFMC supernatants stimulated by these antigens. Both crude and 70-kDa antigens induced higher levels of IFN-gamma, TNF-alpha and IL-10. There was a significant positive correlation between IFN-gamma and the proliferative response induced by crude M. tuberculosis antigen, and an inverse correlation was identified between IL-10 and cell proliferation. IL-4 was not detected in the supernatants of pleural fluid mononuclear cell cultures stimulated by either crude, or recombinant antigens. TNF-alpha was detected in variable amounts in supernatants of PFMC stimulated by all antigens tested. Natural killer cytotoxicity was induced by both crude and 70-kDa antigen. Our results demonstrate that cells present at the site of disease recognized three of the antigens screened, as shown by lymphocyte proliferation and production of regulatory and inflammatory cytokines, and the results obtained with PFMC were consistently higher than those obtained with homologous PBMC.

[Value of determining the activity of adenosine deaminase (ADA) in the differential diagnosis of pleural effusions]

BACKGROUND

Pleural effusion (PE) is a common problem in medical practice. Transudative effusions usually do not present difficulty in diagnosis, in most populations. Exudative PE however, require careful differential diagnosis that include necessarily tuberculosis and metastatic cancer.

METHODS

We have conducted a cross-sectional study of 221 patients with persistent PE, in order to evaluate accuracy of determining adenosine deaminase activity (ADA) for diagnosis of tuberculosis pleuritis. This group of patients, taken mostly from the State Hospital for pulmonary diseases, consecutively, was constituted as follows: 1) Tuberculosis (confirmed, n = 150; likely, n = 9); 2) Cancer (confirmed, n = 21; likely, n = 16; Lymphoma = 3); and 3) Miscellaneous (n = 22). All individuals were submitted to clinical examination, chest X-ray, blood tests, and underwent thoracocentesis with pleural biopsy. Pleural fluids were analyzed by routine tests plus determination of ADA activity using Giusti's Method.

RESULTS

In agreement with previous reports we have found 40 U/L to be the best cutoff point according to a Receiver Operating Curve (ROC) analysis of our data. Sensitivity of ADA activity < or = 40 U/L was 93.3% and specificity 93.5%, resulting in a positive predictive value of 97.2% and a negative predictive value of 85.3%, in this specific population of patients, when taking into account only the individuals with confirmed tuberculosis by histopathology or culture. Three out of the 4 patients with elevated ADA without tuberculosis had lymphoma.

CONCLUSION

ADA determination in pleural fluids, a quick and inexpensive technique, is shown to be an accurate method for identifying tuberculosis pleuritis. Our findings are comparable to reports from other series, and stress how useful it is to incorporate this test to the routine evaluation of pleural effusions in areas of high incidence of tuberculosis.