Tuberculous peritonitis: diagnostic value of ascitic fluid pH and lactate

An acidic microenvironment in Tuberculosis increases extracellular matrix degradation by regulating macrophage inflammatory responses

Mycobacterium tuberculosis (M.tb) infection causes marked tissue inflammation leading to lung destruction and morbidity. The inflammatory extracellular microenvironment is acidic, however the effect of this acidosis on the immune response to M.tb is unknown. Using RNA-seq we show that acidosis produces system level transcriptional change in M.tb infected human macrophages regulating almost 4000 genes. Acidosis specifically upregulated extracellular matrix (ECM) degradation pathways with increased expression of Matrix metalloproteinases (MMPs) which mediate lung destruction in Tuberculosis. Macrophage MMP-1 and -3 secretion was increased by acidosis in a cellular model. Acidosis markedly suppresses several cytokines central to control of M.tb infection including TNF-α and IFN-γ. Murine studies demonstrated expression of known acidosis signaling G-protein coupled receptors OGR-1 and TDAG-8 in Tuberculosis which are shown to mediate the immune effects of decreased pH. Receptors were then demonstrated to be expressed in patients with TB lymphadenitis. Collectively, our findings show that an acidic microenvironment modulates immune function to reduce protective inflammatory responses and increase extracellular matrix degradation in Tuberculosis. Acidosis receptors are therefore potential targets for host directed therapy in patients.

Peritoneal tuberculosis

The peritoneum is one of the locations outside the most common pulmonary tuberculosis. Peritoneal tuberculosis poses a public health problem in endemic regions of the world. The phenomenon of migration, the increased use of immunosuppressive therapy and the epidemic of AIDS have contributed to a resurgence of this disease in regions where it was previously controlled. The aim of this review is to expose the clinical, biologic end radiologic futures of the peritoneal tuberculosis and to present the methods of diagnosis and treatment. The diagnosis of this disease is difficult and still remains a challenge because of its insidious nature, the variability of presentation and limitations of available diagnostic tests. The disease usually presents a picture of lymphocytic exudative ascites. There are many complementary tests with variable sensitivities and specificities to confirm the diagnosis of peritoneal tuberculosis. Isolation of mycobacteria by culture of ascitic fluid or histological examination of peritoneal biopsy ideally performed by laparoscopy remains the investigation of choice. The role of PCR, ascitic adenosine deaminase, interferon gamma and the radiometric BACTEC system can improve the diagnostic yield. An antituberculous treatment with group 1 of the WHO for 6 months is sufficient in most cases.