Cytokines do play a role in pathogenesis of tuberculous meningitis: A prospective study from a tertiary care center in India

Background Though animal studies have suggested a role for proinflammatory cytokines in pathogenesis their exact role in pathogenesis of human meningeal tuberculosis continues to be controversial with different studies yielding contradictory results. Aim and objectives To study the levels of proinflammatory cytokines in serum and cerebrospinal fluid (CSF) of patients with tubercular meningitis (TBM) and to determine whether these correlate with disease severity. Patients and methods Present study included 146 patients with TBM (90- Definite TBM; 56- Probable TBM), diagnosed according to criteria laid by Ahuja et al. which were modified to include CSF nucleic acid based tests. Serum ( n = 146) and CSF ( n = 140) levels of various proinflammatory cytokines (IL-1β, IL-2, IL-6, TNF-α and IFNγ) were compared between TBM patients and healthy volunteers ( n = 99). These levels were correlated with various clinical, radiological and CSF parameters of TBM patients. Results Proinflammatory cytokines include cytokines which promote systemic inflammation. In current study, the serum and CSF levels of various cytokines (IL-2, IL-4, IL-6, IL-1β, IFN-γ and TNF-α) were significantly elevated in TBM patients compared to controls. A significant correlation was found between a) Higher stage of TBM and various cytokines (except for serum IL-6 and CSF IFN-γ); b) High CSF TNF-α, IL-4 and IL-1β with severity of hydrocephalus; c) High CSF IL1β and IFN-γ with presence of exudates on MRI; d) Serum and CSF levels of all cytokines with poor outcome as determined by death or as defined by S and E ADL (Schwab and England activities of daily living) score or by GOS (Glasgow outcome scale) (except for interferon gamma); and e) Serum and CSF IL-4 and IL1β with presence of infarcts on MRI brain. Conclusion Proinflammatory cytokines play an important role in the pathogenesis of TBM and contribute significantly towards severity of disease.