Insights into the lung microenvironment after severe COVID-19

The SARS-CoV-2 is the betacoronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic. Severe COVID-19 affects approximately 10-15% of patients and results in prolonged morbidity and mortality. Little is known about the immunophenotypic changes of the lung parenchyma driven by the viral infection in patients who die of severe COVID-19. Ultrasound-guided lung biopsies (LB) were collected (IRB approval#1561/21) within few hours from death in 15 severe COVID-19 patients between November 2020 and January 2021, in two patients who underwent lung transplantation after COVID-19 and in one patient who had surgery for bacterial superinfection during COVID-19 disease. All samples underwent histologic and immunohistochemistry evaluation and molecular profiling using the nCounter Host Response and Coronavirus Panel plus. As controls, lungs from end-stage usual interstitial pneumonia (UIP;n=9) and from lobectomy for lung cancer (Norm;n=5) were used. Eleven lungs (61%) were positive for SARS-CoV-2 RNA. Signs of diffuse alveolar damage (DAD) were observed in 6 patients (30%). COVID-19 lungs showed a marked macrophage infiltration with M2 polarization compared with controls. Globally, COVID-19 lungs showed distinct molecular profiles from UIP or Norm lungs. Specifically, a marked upregulation of interferon-genes that was directly correlated with SARS-CoV-2 genes was seen in COVID-19 lungs. COVID-19-specific genes signatures (Log2FC >1.5;adj p<0.05) obtained using VENN diagram showed impairment of the STAT3-pathway accompanied by the upregulation of the NFkB signaling. Results herein provide new insights into lung alterations induced by severe COVID-19 and suggest novel potential targets for therapeutic intervention.

Post-COVID-19 Lung Transplantation Italian Pivotal Protocol: Some Ethical Considerations.

SARS­CoV­2 mostly affects the respiratory system with clinical patterns ranging from the common cold to fatal pneumonia. During the first wave of the COVID-19 pandemic, owing to the high number of patients who were infected with SARS­CoV­2 and subsequently recovered, it has been shown that some patients with post-COVID-19 terminal respiratory failure need lung transplantation for survival. There is increasing evidence coming from worldwide observations that this procedure can be performed successfully in post-COVID-19 patients. However, owing to the scarcity of organs, there is a need to define the safety and efficacy of lung transplant for post-COVID-19 patients as compared to patients waiting for a lung transplant for other pre-existing conditions, in order to ensure that sound ethical criteria are applied in organ allocation. The Milan's Policlinic Lung Transplant Surgery Unit, with the revision of the National Second Opinion for Infectious Diseases and the contribution of the Italian Lung Transplant Centres and the Italian National Transplant Centre, set up a pivotal observational protocol for the lung transplant of patients infected and successively turned negative for SARS­CoV­2, albeit with lung consequences such as acute respiratory distress syndrome or some chronic interstitial lung disease. The protocol was revised and approved by the Italian National Institute of Health Ethics Committee. Description of the protocol and some ethical considerations are reported in this article.

COVID19 in Lung Transplanted Patients: Chronicles from an Italian Epicenter

Purpose Lombardy was one of the hardest hit regions in Italy during the COVID19 pandemic. We hereby report our experience with SARS-CoV2 infection in lung transplant recipients. Methods We retrospectively collected clinical data on all the consecutive cases of COVID19 in our centre, based in Milan, from March 2020 to August 2021. Diagnosis was always confirmed by a positive nucleic acid amplification test (RT-PCR) for SARS-CoV-2 on nasopharyngeal swab and/or tracheal aspirate. Results 21 patients were diagnosed with COVID19. Figure 1 summarizes the clinical course of these individuals. We reduced immunosuppressive regimen in all these patients, typically holding the antiproliferative agent and augmenting steroids;when hospitalized, everybody received initial empiric antibiotic treatment with piperacillin/tazobactam and high-dose LMWH. Hydroxychloroquine was used only in the "first wave" (4 patients). One patient was compassionately administered anakinra and remdesivir as a “rescue therapy”. Lymphocitopenia was a common presenting sign (14 patients, 66%). Aspergillus co-infection occurred in 5 patients (24%). Mortality rate was 29%;4 out of these 6 patients were affected by CLAD and 3 had chronic kidney disease. Of note, in March 2021, we tested all our patients for anti-SARS-CoV-2 nucleocapsid antibodies before starting vaccinations: we found three additional seropositive patients, who were not included in the present analysis, but had been presumably affected by an asymptomatic/mild form of the disease. Conclusion Apart from immunosuppression, the majority of our patients presented at least one risk factor for mortality in COVID-19 (diabetes, chronic kidney disease, arterial hypertension) and, for this reason, we felt that they should be hospitalized to enable close monitoring and prompt management of possible complications and deterioration. Clinical course seemed favorable in only two thirds of our patients but, for the time being, none of these individuals showed sign of new-onset CLAD after COVID19.

Lung Allograft Dysfunction in a COVID-19 Transplanted Patient is Associated with a Peculiar Immunopathological Phenotype

Purpose Lung transplantation (LT) after severe SARS-CoV-2 infection is emerging as a life-saving medical procedure for selected patients who experience acute respiratory distress syndrome (ARDS). We present the first immunopathological evaluation of a lung allograft rejection in a patient who underwent LT because of irreversible ARDS related to COVID-19. Methods Two male patients with irreversible ARDS caused by COVID-19 underwent bilateral LT at our Institution. A surveillance transbronchial biopsy (TBB) was performed 2 months after LT in the first patient (Pt#1), while the second patient (Pt#2) died because of allograft rejection at day 62 post LT and explanted lungs were retrieved. CT imaging of the lungs was performed three days before death. Morphological examination was performed by H&E, whereas the immunophenotyping was performed by immunohistochemistry. Results Imaging and morphological examination of Pt#2 lungs indicated the presence of a graft dysfunction with features of a restrictive, widespread usual interstitial pneumonia-like syndrome (Fig. 1A, B). The immunophenotyping showed that B-lymphocytes (CD20-positive) were nearly absent, CD8-T-cells were not particularly expanded (mean positive cells within the lung stroma=13.8%;Fig. 1C), and the CD4/CD8 ratio was not decreased (Fig. 1D). The T-regs (Foxp3-positive) were 6% of the overall population (Fig. 1E). Analysis of the immune checkpoint molecules PD1, Tigit, CTLA4 and PDL1 showed that the expression of PD-L1 alone was highly increased in vases and in alveolar cells of rejected lungs, whereas it was nearly undetectable in the TBB from Pt#1 (Fig. 1F, G). Conclusion PDL1 expression in vases was previously documented as a sign of indirect ARDS. Together with our preliminary data, we can hypothesize that PDL1 may play a role in tissue effacement and graft failure, possibly indicating poor allograft prognosis.

Lung Transplantation for Acute Respiratory Distress Syndrome Related to COVID-19: The Lesson Learned from the First Two Cases

Purpose The respiratory system, and namely the lung, is undoubtedly the preferential target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The clinical pictures are extremely various, up to the intensive care unit (ICU) admission for acute respiratory distress syndrome (ARDS). Lung transplantation (LT) is a consolidate therapeutic option for end-stage chronic respiratory diseases. Its role in an acute setting is questionable, particularly due to lack of experiences, donor shortage, and the difficulty to fully evaluate the potential recipient. We report our preliminary experience with the first two cases of LT for SARS-CoV-2 related ARDS, trying to provide some food for thought. Methods We retrospectively analysed our first two cases of bilateral LT for ARDS after COVID-19. We recorded data on pre-transplantation clinical course, transplantation management and outcomes. Results The two patients had a similar clinical evolution of COVID-19. Transplantations were successful in both cases;the first patient is alive and in good condition 5 months after transplantation, while the second died 62 days after surgery. Table 1 shows clinical details and relevant time-points. Conclusion Our experience showed that LT for COVID-19 is feasible. Importantly, observing a dedicated protocol made the procedure safe for the healthcare staff involved. On the other hand, our second unsuccessful case poses relevant questions: first of all, lung transplantation should be reserved to highly selected patient, after careful clinical, infective as well as psychiatric evaluation. The ethical aspects should also be considered in this situation, with regard to the centre rate mortality on waiting list. Anyway, the potential role of LT in the acute and sub-acute/chronic settings suggests the need for maintaining LT centre active during pandemic. Finally, COVID-19, once more, imposes to share clinical experiences.