CD26-inhibition correlates with the absence of chronic lung allograft dysfunction and decreases fibroblast activity in vitro

Objective

Chronic lung allograft dysfunction (CLAD) limits the survival after lung transplantation (Tx). CLAD is characterized by progressive fibrosis of small airways and lung parenchyma. No effective therapy is available that reverses or prevents CLAD. CD26 is a molecule with enzymatic activity also playing a key role in the progression of fibrotic diseases. Here, we analyzed the inhibitory effect of CD26 on fibroblast activity in vitro and the role of CD26-inhibition on allograft rejection in lung transplant patients.

Methods

Profibrogenic mRNA and protein levels were analyzed in vitro on the CD26-expressing fibroblast cell line Wi-38 using RT-qPCR and Western blot. CD26 was inhibited by Vildagliptin. Migration and proliferation activity of activated fibroblasts were analyzed by Incucyte® and Celltiter-Glo®. Characteristics of patients undergoing lung Tx between 2004 and 2021 were reviewed. Lung biopsies were analyzed by immunohistochemistry (IHC) for CD26.

Results

In vitro, the expression of profibrogenic genes (αSMA, FAPα, IGFBP7, Collagen 3 and Fibronectin) was significantly reduced in activated lung fibroblasts by Vildagliptin treatment. Also, migration and proliferation activity were attenuated by Vildagliptin. In 221 patients analyzed, CLAD was absent in 34 patients treated with the CD26-inhibitor Sitagliptin vs. an incidence of 18% in patients without Sitagliptin intake (p=0.02). Five-year survival in patients on Sitagliptin was significantly improved vs. patients without CD26-inhibitor intake (80% vs. 58%, p=0.006). Likewise, the incidence of acute cellular rejection (ACR) was significantly reduced in patients on Sitagliptin (7% vs. 35%, p=0.01). IHC of patient lung biopsies showed expression of CD26 in perifibrotic areas of CLAD lesions. Additional clinical data from University Hospital Zurich and from University Hospital Padua confirmed the finding that Sitagliptin intake correlated with the absence of acute and chronic allograft rejection.

Conclusion

CD26-inhibition attenuates key pro-fibrotic mediators and fibroblast activity in vitro. Impressively, patients on CD26-inhibitor did not show any CLAD. Moreover, ACR was significantly reduced. Gliptins which are in routine clinical use for the treatment of type II diabetes therefore seem to have great potential to be repurposed for a novel clinical application against lung allograft rejection.

A Case of Prolonged Hospital Acquired COVID-19 Pneumonia in a Lung Transplant Recipient: Management and Outcome

Introduction

Lung transplant recipients are at increased risk of SARS-CoV2 infection due to immunosuppression and their management has yet to be standardized. We report a case of prolonged COVID-19 infection in a lung recipient acquired after transplant during the hospital stay.

Case Report

A 52-year-old lady with interstitial disease associated to systemic sclerosis underwent bilateral lung transplantation on 04/10/21. Donors and recipient microbiological tests for SARS-CoV2 were negative on molecular swabs performed before transplantation (04/07 and 04/10). Transplantation was uneventful and the recipient was extubated the subsequent day. Twelve days later, a surveillance molecular nose-pharyngeal swab was positive for SARS-CoV2. The positivity for subgenomic analysis revealed productive infection. At first monitoring biopsy, multiple foci of diffuse alveolar damage, significant cytopathic features of pneumocytes, microthrombi of capillaries, and extensive edema were highly suggestive of COVID-19 pneumonia. High viral load was also detected in lung biopsy by RT-PCR. She presented mild respiratory symptoms (cough with low oxygen supplementation) and the CT scan revealed an area of consolidation at the right lower lobe. Monoclonal antibody therapy (Bamlanivimab and Etesevimab) associated with remdesevir was started, IV immunoglobulins were administered while mycophenolate mofetil was discontinued. The patient was closely monitored until the nose-pharyngeal swab turned negative two months after the first positivity associated with a significant clinical improvement. At the last follow-up, five months after transplantation, she had good pulmonary function, no immunological disorders and no signs related to long COVID-19.

Summary

This is a case of prolonged hospital acquired COVID-19 related pneumonia in a lung recipient. Immunocompromized patients present a longer viral clearance. In this fragile population a strict clinical, radiological and histopathological monitoring associated with encouragement of vaccination are mandatory.