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The concept of biological identity has been traditionally a central issue in immunology. The assumption that entities foreign to a specific organism should be rejected by its immune system, while self-entities do not trigger an immune response is challenged by the expanded immunotolerance observed in pregnancy. To explain this "immunological paradox", as it was first called by Sir Peter Medawar, several mechanisms have been described in the last decades. Among them, the intentional transfer and retention of small amounts of cells between a mother and her child have gained back attention. These microchimeric cells contribute to expanding allotolerance in both organisms and enhancing genetic fitness, but they could also provoke aberrant alloimmune activation. Understanding the mechanisms used by microchimeric cells to exert their function in pregnancy has proven to be challenging as per definition they are extremely rare. Profiting from studies in the field of transplantation and cancer research, a synergistic effect of microchimerism and cellular communication based on the secretion of extracellular vesicles (EVs) has begun to be unveiled. EVs are already known to play a pivotal role in feto-maternal tolerance by transferring cargo from fetal to maternal immune cells to reshape their function. A further aspect of EVs is their function in antigen presentation either directly or on the surface of recipient cells. Here, we review the current understanding of microchimerism in the feto-maternal tolerance during human pregnancy and the potential role of EVs in mediating the allorecognition and tropism of microchimeric cells.

Pseudomonas aeruginosa, is an opportunistic bacterium with hight prevalence in diverse pulmonary infections. Although several genes have been involved in the resistance and evasion system of the immunological response of the host, little information is known about the inflammatory, degradative, and cell binding response induced by P. aeruginosa on human lung alveolar epithelial cells. The purpuse of this study was dtermine the cytokine expression (IL-1β, and TNFα), pro matrix metalloproteinase activaction (proMMP-2 and proMMP-9), and the effects on the cell-binding adhesion protein (E-cadherin) in an in vitro model of human lung alveolar epithelial cells. A549 cells were stimulated with different colony-forming units of P. aeruginosa for 3, 6, and 24 hours. After these times, culture media was collected, IL-1β and TNFα were evaluated by ELISA; proMMP-2 and -9 were determined by substrate gel zymography; and the isoform of actMMP-9 and E-cadherin assessed by immunoreactivity on A549 cells. Our results demonstrate that P. aeruginosa induces mainly the secretion of TNFα, increasing the actMMP-9, and significantly reduces the level of E-cadherin in the A549 cells. In summary, the inflammatory/degradative process induced by P.aeruginosa modulates the expression of the E-cadherin protein. The probable clinical implications of this study suggests the use of inhibitos that reduced the degradative activity of proMMP-9 wich will be demonstrated in the next phase of this study.

Pseudomonas aeruginosa, is an opportunistic bacterium with a high prevalence in diverse pulmonary infections. Although several genes are involved in the system of resistance and evasion of the immunological response of the host, little is known about the inflammatory, degradative, and cell-binding response induced by P. aeruginosa in human lung alveolar epithelial cells. The purpose of this study was to determine the cytokine expression (IL-1β and TNFα), pro matrix metalloproteinases activation (proMMP-2 and proMMP-9), and the effects on the cell-binding adhesion protein (E-cadherin) in an in vitro model of human lung alveolar epithelial cells. A549 cells were stimulated with a different number of colony-forming units of P. aeruginosa for 3, 6, and 24 hours. Subsequently, the culture medium was collected, IL-1β and TNFα levels were evaluated by ELISA; proMMP-2 and -9 levels were determined by substrate gel zymography, and the MMP-9 and E-cadherin assessed by immunostaining of A549 cells. Our results demonstrated that P. aeruginosa induces mainly the secretion of TNFα, increases actMMP-9 level, and significantly reduces the level of E-cadherin in the A549 cells. In summary, the inflammatory/degradative process induced by P. aeruginosa modulates the expression of the E-cadherin protein. The probable clinical implications of this study suggest the use of inhibitors that reduce the degradative activity of proMMP-9 which will be further explored in the next phase of this study.