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.

IMPACT OF A SARS-COV2 INFECTION IN PATIENTS WITH CELIAC DISEASE

Objective. No data are available on the effects of SARS-CoV2 infection in patients with celiac disease (CD) in terms of development of related symptoms and antibodies. We aimed to investigate the impact of SARS-CoV2 infection in CD. Design. During lockdown (March-May 2020), celiac patients living in Milano were interviewed about the development of COVID-19 resembling symptoms, adherence to an anti-virus lifestyle and gluten-free diet (GFD), and were asked to reply to a stress questionnaire. The development of anti SARSCoV2 IgG and IgA (anti RBD and N proteins) and the expression of duodenal ACE2 receptor were also investigated. Whenever available, duodenal histology, anti-tissue transglutaminase IgA (tTGA), immunologic comorbidities and GFD adherence were analyzed as possible risk factors. Results. 362 celiac patients have been interviewed and 42 (11%) reported COVID-19 resembling symptoms. The presence of symptoms was not influenced by positivity of tTGA, presence of duodenal atrophy or adherence to GFD. 37% of symptomatic patients showed anti SARS-CoV2 Immunoglobulins (Ig). Globally, 18% of celiac patients had anti SARS-CoV2 Ig vs 25% of non-celiac controls (p=0.18). Levels of anti RBD IgG/IgA and anti N IgG did not differ from non-celiac controls. Celiac patients had significantly lower levels of anti N IgA. ACE2 receptor was detected in the non-atrophic duodenal mucosa of celiac patients;atrophy was associated with a weaker expression of ACE2 receptor. Conclusion. CD patients show an anti SARS-CoV2 Ig positivity/profile similar to non-celiac controls, except for anti-N IgA. Main celiac biomarkers and adherence to the GFD do not influence the development of different antibody profiles.

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.