CTSS and infection: A comparative study using a pathogenic strain M. tuberculosis and a non-pathogenic strain M. smegmatis revealed that following infection with M. tuberculosis mRNAs for the majority of cathepsins and cystatins were down-regulated in M0 (Cts B, C, D, E, G, K, O, S, V, and W and cystatins B, C, D, SA, SN, and E/M) and M1 (Cts B, C, F, K, S, W, and Z and cystatin C) human primary macrophages, in contrast to M. smegmatis that induced up-regulation of most cathepsins in both type of cells.