Tolerogenic Lung Allograft Microenvironment Suppresses Pathogenic Tissue Remodeling Following Respiratory Virus Infection in Mice.

Tolerance after lung transplantation is associated with the induction of Foxp3 regulatory T cell-enriched bronchus-associated lymphoid tissue, which suppresses local and systemic alloimmune responses. How this tolerogenic graft environment shapes responses to respiratory viral infections, a known contributor to adverse outcomes after lung transplantation, remains unknown. Using a mouse model of a seasonally circulating parainfluenza virus, we found that acute infection of tolerant lung allografts results in temporary reductions of both bronchus-associated lymphoid tissue size and abundance of graft-resident Foxp3 cells, but doesn't trigger rejection.

Tissue-resident CCR2 macrophage TREM-1/3 signaling is necessary for monocyte and neutrophil recruitment to injured hearts.

Triggering receptor expressed on myeloid cells 1 (TREM-1) has been shown to amplify inflammatory signals, such as Toll-like receptor signaling, after infection and sterile injury. While previous studies have demonstrated that TREM-1 activation in circulating immune cells promotes injury, the role of TREM-1 signaling in tissue-resident cells in the context of sterile inflammation remains poorly understood. Here, we used a cardiac transplantation model to dissect how Trem1/3 expression on heart-resident cells regulates sterile inflammation.

Bronchus-associated lymphoid tissue in lung transplantation: a facilitator of rejection or regulator of tolerance?

The role of bronchus-associated lymphoid tissue (BALT) in the regulation of immune responses to transplanted lungs remains an area of interest and controversy. Early studies in a rat pulmonary transplant model suggested BALT may accelerate rejection of grafts by inducing a local and systemic inflammatory response. Such observations were corroborated in intrapulmonary tracheal transplant models in the rat.

mitral valve endocarditis in a patient with a history of mitral valve annuloplasty.

A woman with a history of congenital heart disease status post multiple valve operations including mitral valve repair presented with 2 months of low back pain and general malaise. Blood cultures returned positive for Gram-positive cocci. While transthoracic echocardiography did not identify vegetations, transoesophageal echocardiography visualised vegetations on the patient's mitral valve, which had previously undergone repair with annuloplasty.