The nature of chronic rejection after lung transplantation: a murine orthotopic lung transplant study.

Introduction: Chronic rejection is a major complication post-transplantation. Within lung transplantation, chronic rejection was considered as airway centred. Chronic Lung Allograft Dysfunction (CLAD), defined to cover all late chronic complications, makes it more difficult to understand chronic rejection from an immunological perspective. This study investigated the true nature, timing and location of chronic rejection as a whole, within mouse lung transplantation. Methods: 40 mice underwent an orthotopic left lung transplantation, were sacrificed at day 70 and evaluated by histology and in vivo µCT. For timing and location of rejection, extra grafts were sacrificed at day 7, 35, 56 and investigated by ex vivo µCT or single cell RNA (scRNA) profiling. Results: Chronic rejection originated as innate inflammation around small arteries evolving toward adaptive organization with subsequent end-arterial fibrosis and obliterans. Subsequently, venous and pleural infiltration appeared, followed by airway related bronchiolar folding and rarely bronchiolitis obliterans was observed. Ex vivo µCT and scRNA profiling validated the time, location and sequence of events with endothelial destruction and activation as primary onset. Conclusion: Against the current belief, chronic rejection in lung transplantation may start as an arterial response, followed by responses in venules, pleura, and, only in the late stage, bronchioles, as may be seen in some but not all patients with CLAD.

Pilot study for immunoglobulin E as a prognostic biomarker in coronavirus disease 2019.

BACKGROUND: Laboratory biomarkers to estimate the severity of coronavirus disease 2019 (COVID-19) are crucial during the pandemic since resource allocation must be carefully planned. AIMS: To evaluate the effects of basal serum total immunoglobulin E (IgE) levels and changes in inflammatory parameters on the clinical progression of patients hospitalised with COVID-19. METHODS: Patients hospitalised with confirmed COVID-19 were included in the study. Laboratory data and total IgE levels were measured on admission. Lymphocyte, eosinophil, ferritin, d-dimer and C-reactive protein parameters were recorded at baseline and on the 3rd and 14th days of hospitalisation. RESULTS: The study enrolled 202 patients, of which 102 (50.5%) were males. The average age was 50.17 ± 19.68 years. Of the COVID-19 patients, 41 (20.3%) showed clinical progression. Serum total IgE concentrations were markedly higher (172.90 (0-2124) vs 38.70 (0-912); P < 0.001) and serum eosinophil levels were significantly lower (0.015 (0-1.200) vs 0.040 (0-1.360); P = 0.002) in clinically worsened COVID-19 patients when compared with stable patients. The optimal cut-off for predicting clinical worsening was 105.2 ng/L, with 61% sensitivity, 82% specificity, 46.3% positive predictive value and 89.2% negative predictive value (area under the curve = 0.729). Multivariable analysis to define risk factors for disease progression identified higher total IgE and C-reactive protein levels as independent predictors. CONCLUSIONS: Our single-centre pilot study determined that total IgE levels may be a negative prognostic factor for clinical progression in patients hospitalised due to COVID-19 infection. Future studies are required to determine the impact of individuals' underlying immune predispositions on outcomes of COVID-19 infections.