The introduction of mesenchymal stromal cells induces different immunological responses in the lungs of healthy and M. tuberculosis infected mice

Abstract

Mesenchymal stromal cells (MSC) have strong immunomodulatory properties and therefore can be used to control inflammation and tissue damage. It was suggested recently that MSC injections can be used to treat multi-drug resistant tuberculosis (TB). However, MSC trafficking and immunomodulatory effects of MSC injections during Mycobacterium tuberculosis (Mtb) infection have not been studied. To address this issue we have analyzed MSC distribution in tissues and local immunological effects of MSC injections in Mtb infected and uninfected mice. After intravenous injection, MSC accumulated preferentially in the lungs where they were located as cell aggregates in the alveolar walls. Immunological analysis of MSC effects included detection of activated, IFN-γ and IL-4 producing CD4+ lymphocytes, the frequency analysis of dendritic cells (CD11c+F4/80) and macrophages (CD11c-F4/80+) located in the lungs, the expression of IA/IE and CD11b molecules by these cells, and evaluation of 23 cytokines/chemokines in lung lysates. In the lungs of uninfected mice, MSC transfer markedly increased the percentage of IFN-γ+ CD4+ lymphocytes and dendritic cells, elevated levels of IA/IE expression by dendritic cells and macrophages, augmented local production of type 2 cytokines (IL-4, IL-5, IL-10) and chemokines (CCL2, CCL3, CCL4, CCL5, CXCL1), and downregulated type 1 and hematopoietic cytokines (IL-12p70, IFN-γ, IL-3, IL-6, GM-CSF). Compared to uninfected mice, Mtb infected mice had statistically higher “background” frequency of activated CD69+ and IFN-γ+ CD4+ lymphocytes and dendritic cells, and higher levels of cytokines in the lungs. The injections of MSC to Mtb infected mice did not show statistically significant effects on CD4+ lymphocytes, dendritic cells and macrophages, only slightly shifted cytokine profile, and did not change pathogen load or slow down TB progression. Lung section analysis showed that in Mtb infected mice, MSC could not be found in the proximity of the inflammatory foci. Thus, in healthy recipients, MSC administration dramatically changed T-cell function and cytokine/chemokine milieu in the lungs, most likely, due to capillary blockade. But, during Mtb infection, i.e., in the highly-inflammatory conditions, MSC did not affect T-cell function and the level of inflammation. The findings emphasize the importance of the evaluation of MSC effects locally at the site of their predominant post-injection localization and question MSC usefulness as anti-TB treatment.

Tuberculosis: progress and advances in development of new drugs, treatment regimens, and host-directed therapies

“…136 Mesenchymal stromal cells (MSC) are nonhematopoietic progenitor cells with immunomodulatory and antibacterial properties, [137][138] that improve immune responses and lung pathology in human and murine TB. [139][140] Another immunotherapeutic approach involves modulation of immune regulatory cells, specifically myeloid-derived suppressor cells (MDSC) [141][142] MDSC are increased in TB, display T-cell immunosuppressive properties, [143][144][145] and harbour Mtb, suggesting that MDSC-targeting strategies should also be considered in TB HDT design.…”

Mesenchymal stem cells protect against malaria pathogenesis by reprogramming erythropoiesis in the bone marrow

“…We standardized the infusion protocol to obtain an optimal protective immune response and then proceeded to study the mechanisms of host protection mediated by MSCs in malaria infection. The role of MSCs in the pathogenesis of infectious diseases, except for Mycobacterium tuberculosis infection 38 , has not been explored. M. tuberculosis infects MSCs and these cells in turn play a role in establishing dormancy of the mycobacterial organisms 39 .…”

Th1, Th17, and Th1Th17 Lymphocytes during Tuberculosis: Th1 Lymphocytes Predominate and Appear as Low-Differentiated CXCR3+CCR6+ Cells in the Blood and Highly Differentiated CXCR3+/−CCR6− Cells in the Lungs

“…The cells were isolated using CD14 MicroBeads (Miltenyi Biotec, Auburn, CA; cell purity . 90%) and stained with CFSE (Thermo Fisher Scientific), according to the previously described procedure (34). The remaining PBMCs (∼5 3 10 7 from each donor) were stained with PerCP-Cy5.5-anti-CD4, PE-anti-R6, and allophycocyaninanti-X3 Abs or with PerCP-Cy5.5-anti-CD4, PE-anti-R6, allophycocyanin-anti-CD62L, and BV421-anti-X3 Abs.…”