TUBERCULOUS PERICARDITIS

Comparison of the frequency and phenotypic profile of Mycobacterium tuberculosis-specific CD4 T cells between the site of disease and blood in pericardial tuberculosis

Studies of the immune response at the site of disease in extra-pulmonary tuberculosis (EPTB) disease are scarce. In this study, we compared the cellular profile of Mycobacterium tuberculosis (Mtb)-specific T cells in pericardial fluid and peripheral blood in patients with pericardial TB (PCTB). Whole blood and pericardial fluid (PCF) samples were collected at the time of diagnostic sampling, with repeat blood sampling after completion of anti-tubercular treatment (ATT) in 16 PCTB patients, most of them being HIV-1 infected (n=14). These samples were stimulated ex vivo and the phenotypic and functional cellular profile of PCF and blood was assessed by flow cytometry. We found that lymphocytes were the predominant cell type in PCF in PCTB, with a preferential influx of CD4 T cells. The frequencies of TNF-α producing Mtb-specific granulocytes and Mtb-specific CD4 T cells were significantly higher in PCF compared to blood. Mtb-specific CD4 T cells in PCF exhibited a distinct phenotype compared to those in blood, with greater GrB expression and lower CD27 and KLRG1 expression. We observed no difference in the production IFNγ, TNF or IL-2 by Mtb-specific CD4 T cells between the two compartments, but MIP-1β production was lower in the PCF T cells. Bacterial loads were not associated with alterations in the phenotype or function of Mtb-specific CD4 T cells. Upon ATT completion, HLA-DR, Ki-67 and GrB expression was significantly decreased, and relative IL-2 production was increased in peripheral Mtb-specific CD4 T cells. Overall, using an ex vivo assay to compare the immune response towards Mtb in PCF and in blood, we identified significant difference in the phenotypic profile of Mtb-specific CD4 T response between these two compartments. Moreover, we show that the activation profile of peripheral Mtb-specific CD4 T cells could be used to monitor treatment response in PCTB.

Tuberculous pericarditis with and without HIV

The human immunodeficiency virus (HIV) has altered the epidemiology, clinical manifestations, treatment considerations and natural history of tuberculous (TB) pericarditis with significant implications for clinicians. The caseload of TB pericarditis has risen sharply in TB endemic areas of the world where co-infection with HIV is common. Furthermore, TB is the cause in greater than 85 % of cases of pericardial effusion in HIV-infected cohorts. In the absence of HIV, the morbidity of TB pericarditis is primarily related to the ferocity of the immune response to TB antigens within the pericardium. In patients with HIV, because TB pericarditis more often occurs as part of a disseminated process, the infection itself has a greater impact on the morbidity and mortality. HIV-associated TB pericarditis is a more aggressive disease with a greater degree of myocardial involvement. Patients have larger pericardial effusions with more frequent hemodynamic compromise and more significant ST segment changes in the electrocardiogram. HIV alters the natural history and outcomes of TB pericarditis. Immunocompromised participants appear less likely to develop constrictive pericarditis and have a significantly higher mortality compared with their immunocompetent counterparts. Finally co-infection with HIV has resulted in a number of areas of uncertainty. The mechanisms of myocardial dysfunction are unclear, new methods of improving the yield of TB culture and establishing a rapid bacterial diagnosis remain a major challenge, the optimal duration of anti-TB therapy has yet to be established, and the role of corticosteroids has yet to be resolved.

A modern approach to tuberculous pericarditis

The human immunodeficiency virus (HIV) epidemic has been associated with an increase in all forms of extrapulmonary tuberculosis including tuberculous pericarditis. Tuberculosis is responsible for approximately 70% of cases of large pericardial effusion and most cases of constrictive pericarditis in developing countries, where most of the world's population live. However, in industrialized countries, tuberculosis accounts for only 4% of cases of pericardial effusion and an even smaller proportion of instances of constrictive pericarditis. Tuberculous pericarditis is a dangerous disease with a mortality of 17% to 40%; constriction occurs in a similar proportion of cases after tuberculous pericardial effusion. Early diagnosis and institution of appropriate therapy are critical to prevent mortality. A definite or proven diagnosis is based on demonstration of tubercle bacilli in pericardial fluid or on histologic section of the pericardium. A probable or presumed diagnosis is based on proof of tuberculosis elsewhere in a patient with otherwise unexplained pericarditis, a lymphocytic pericardial exudate with elevated biomarkers of tuberculous infection, and/or appropriate response to a trial of antituberculosis chemotherapy. Treatment consists of 4-drug therapy (isoniazid, rifampicin, pyrazinamide, and ethambutol) for 2 months followed by 2 drugs (isoniazid and rifampicin) for 4 months regardless of HIV status. It is uncertain whether adjunctive corticosteroids are effective in reducing mortality or pericardial constriction, and their safety in HIV-infected patients has not been established conclusively. Surgical resection of the pericardium is indicated for those with calcific constrictive pericarditis or with persistent signs of constriction after a 6 to 8 week trial of antituberculosis treatment in patients with noncalcific constrictive pericarditis.

Noninvasive detection of active pericardial bleeding using cardiac blood pool scintigraphy

The diagnosis of active pericardial bleeding has traditionally depended on an invasive documentation by needle aspiration, angiography, or direct inspection. Blood pool scintigraphy performed in 2 patients just before and after the development of hemopericardium revealed unique images in which acute pericardial bleeding manifested itself by an additional blood pool adjacent to the cardiac chambers. With appropriate attention to technical factors, such distinctive images should be highly specific for active bleeding into the pericardial sac.

Tuberculous pericarditis

Images

Discussion on chronic diseases of the pericardium

Images