EXPLOITING IMMUNOTHERAPY IN MYCOBACTERIUM TUBERCULOSIS-INFECTED MICE: SPHINGOSINE 1-PHOSPHATE TREATMENT RESULTS IN A PROTECTIVE OR DETRIMENTAL EFFECT DEPENDING ON THE STAGE OF INFECTION

Sphingosine 1-phosphate (S1P) is a natural lysophospholipid able to enhance antimycobacterial innate immune response. In the present study, we address the possible therapeutic role of SIP administered during primary or acute infection in mice aerogenically infected with Mycobacterium tuberculosis (MTB). Results show that the administration of SIP during primary infection significantly reduces the presence of MTB-infected cells within pulmonary granulomas and mycobacterial burden in the lung and in the spleen. However, if SIP treatment was started during acute infection, a detrimental effect was observed in terms of pulmonary histopathology and mycobacterial burden in the lung and in the spleen. Taken together, these results show that SIP can exert a therapeutic effect as a treatment of primary infection only.