Mycobacterium tuberculosis Coinfection Has No Impact on Plasmodium berghei ANKA-Induced Experimental Cerebral Malaria in C57BL/6 Mice

Cerebral malaria (CM) is the most severe complication of human infection with Plasmodium falciparum. The mechanisms predisposing to CM are still not fully understood. Proinflammatory immune responses are required for the control of blood-stage malaria infection but are also implicated in the pathogenesis of CM. A fine balance between pro- and anti-inflammatory immune responses is required for parasite clearance without the induction of host pathology. The most accepted experimental model to study human CM is Plasmodium berghei ANKA (PbANKA) infection in C57BL/6 mice that leads to the development of a complex neurological syndrome which shares many characteristics with the human disease. We applied this model to study the outcome of PbANKA infection in mice previously infected with Mycobacterium tuberculosis, the causative agent of tuberculosis. Tuberculosis is coendemic with malaria in large regions in the tropics, and mycobacteria have been reported to confer some degree of unspecific protection against rodent Plasmodium parasites in experimental coinfection models. We found that concomitant M. tuberculosis infection did not change the clinical course of PbANKA-induced experimental cerebral malaria (ECM) in C57BL/6 mice. The immunological environments in spleen and brain did not differ between singly infected and coinfected animals; instead, the overall cytokine and T cell responses in coinfected mice were comparable to those in animals solely infected with PbANKA. Our data suggest that M. tuberculosis coinfection is not able to change the outcome of PbANKA-induced disease, most likely because the inflammatory response induced by the parasite rapidly dominates in mice previously infected with M. tuberculosis.