As illustrated earlier, MSC(BM)s secrete CCL2 in response to TLR ligands or bacterial infection to induce monocyte emigration to the circulation, thereby enhancing resistance to bacterial infections.115 The chemotaxis mediated by cues from MSCs assists in recruiting T cells for Fas ligand (FasL)-mediated apoptosis and diminishing excessive inflammatory reactions in treating autoimmune disorders, such as systemic sclerosis and colitis.116 The chemotactic gradients have a short half-live and undergo degradation by extracellular proteases. This evidence concerns the gene CCL2 and bacterial infectious disease.