Invasive fungal infections after respiratory viral infections in lung transplant recipients are associated with lung allograft failure and chronic lung allograft dysfunction within 1 year.

BACKGROUND: Respiratory viral infections (RVI) are associated with chronic lung allograft dysfunction (CLAD) and mortality in lung transplant recipients (LTRs). However, the prevalence and impact of secondary invasive fungal infections (IFIs) post RVIs in LTRs have not been investigated. METHODS: We performed a single center retrospective study including LTRs diagnosed with 5 different respiratory viral pathogens between January 2010 to May 2021 and evaluated their clinical outcomes in 1 year. The risk factors of IFIs were evaluated by logistic regression. The impact of IFIs on CLAD stage progression/death was examined by Cox regression. RESULTS: A total of 202 RVI episodes (50 influenza, 31 severe acute respiratory syndrome coronavirus-2, 30 metapneumovirus, 44 parainfluenza, and 47 respiratory syncytial virus) in 132 patients was included for analysis. Thirty-one episodes (15%) were associated with secondary IFIs, and 27 occurred in LTRs with lower respiratory tract infection (LRTI; 28% from 96 LRTI episodes). Aspergillosis was the most common IFI (80%). LTRs with IFIs had higher disease severity during RVI episodes. In multivariable analysis, RVI with LTRI was associated with IFI (adjusted odds ratio [95% confidence interval (CI)] of 7.85 (2.48-24.9). Secondary IFIs were associated with CLAD stage progression/death after accounting for LRTI, pre-existing CLAD, intensive care unit admission, secondary bacterial pneumonia and underlying lung diseases pre-transplant with adjusted hazard ratio (95%CI) of 2.45 (1.29-4.64). CONCLUSIONS: This cohort demonstrated 15% secondary IFI prevalence in LTRs with RVIs. Importantly, secondary IFIs were associated with CLAD stage progression/death, underscoring the importance of screening for fungal infections in this setting.

Interferon-stimulated and metallothionein-expressing macrophages are associated with acute and chronic allograft dysfunction after lung transplantation.

BACKGROUND: Lung transplant recipients experience episodes of immune-mediated acute lung allograft dysfunction (ALAD). ALAD episodes are a risk factor for chronic lung allograft dysfunction (CLAD), the major cause of death after lung transplantation. Our objective was to determine key cellular elements in dysfunctional lung allografts, with a focus on macrophages. METHODS: We have applied single-cell RNA sequencing (scRNAseq) to bronchoalveolar lavage cells from stable and ALAD patients and to cells from explanted CLAD lung tissue. RESULTS: We identified 2 alveolar macrophage (AM) subsets uniquely represented in ALAD. Using pathway analysis and differentially expressed genes, we annotated these as pro-inflammatory interferon-stimulated gene (ISG) and metallothionein-mediated inflammatory (MT) AMs. Functional analysis of an independent set of AMs in vitro revealed that ALAD AMs exhibited a higher expression of CXCL10, a marker of ISG AMs, and increased secretion of pro-inflammatory cytokines compared to AMs from stable patients. Using publicly available bronchoalveolar lavage scRNAseq datasets, we found that ISG and MT AMs are associated with more severe inflammation in COVID-19 patients. Analysis of cells from 4 explanted CLAD lungs revealed similar macrophage populations. Donor and recipient cells were identified using expressed single nucleotide variations. We demonstrated contributions of donor and recipient cells to all AM subsets early post-transplant, with loss of donor-derived cells over time. CONCLUSIONS: Our data reveal extensive heterogeneity among lung macrophages after lung transplantation and indicates that specific sub-populations may be associated with allograft dysfunction, raising the possibility that these cells may represent important therapeutic targets.

The Year in Cardiothoracic Transplant Anesthesia: Selected Highlights From 2020 Part I - Lung Transplantation.

This special article focuses on the highlights in cardiothoracic transplantation literature in the year 2020. Part I encompasses the recent literature on lung transplantation, including the advances in preoperative assessment and optimization, donor management, including the use of ex-vivo lung perfusion, recipient management, including those who have been infected with coronavirus disease 2019, updates on the perioperative management, including the use of extracorporeal membrane oxygenation, and long-term outcomes.

Viral infections in lung transplantation.

Viral infections account for up to 30% of all infectious complications in lung transplant recipients, remaining a significant cause of morbidity and even mortality. Impact of viral infections is not only due to the direct effects of viral replication, but also to immunologically-mediated lung injury that may lead to acute rejection and chronic lung allograft dysfunction. This has particularly been seen in infections caused by herpesviruses and respiratory viruses. The implementation of universal preventive measures against cytomegalovirus (CMV) and influenza (by means of antiviral prophylaxis and vaccination, respectively) and administration of early antiviral treatment have reduced the burden of these diseases and potentially their role in affecting allograft outcomes. New antivirals against CMV for prophylaxis and for treatment of antiviral-resistant CMV infection are currently being evaluated in transplant recipients, and may continue to improve the management of CMV in lung transplant recipients. However, new therapeutic and preventive strategies are highly needed for other viruses such as respiratory syncytial virus (RSV) or parainfluenza virus (PIV), including new antivirals and vaccines. This is particularly important in the advent of the COVID-19 pandemic, for which several unanswered questions remain, in particular on the best antiviral and immunomodulatory regimen for decreasing mortality specifically in lung transplant recipients. In conclusion, the appropriate management of viral complications after transplantation remain an essential step to continue improving survival and quality of life of lung transplant recipients.