MMP12 and infection: By 4 hrs post H37Rv-infection there appeared to be a shift towards the more protective pro-inflammatory type 1 response, similar to the response observed by 4 hrs post Δ-mce1 H37Rv-infection, indicated by the down-regulation of the IL-13ra1 receptor, Ccl24 and Pparg in combination with an up-regulation of the transcription of the genes Cd36, Mmp9 and Mmp12 and the genes coding for the pro-inflammatory cytokines IL-12 (Il12b) [Table 2] and IL-1 (Il1a and Il1b [data not shown]).