Short airway telomeres are associated with primary graft dysfunction and chronic lung allograft dysfunction

The lung transplant endobronchial biopsy: A forgotten specimen comes of age

Mucosal or endobronchial biopsies (EBB) are typically used in the diagnosis of directly visualized bronchial lesions, infection, and sarcoidosis, but their utility in the evaluation of lung transplant recipients is controversial. EBB represents an attractive alternative to transbronchial biopsy (TBB): EBB provides straightforward sampling of airway pathology with decreased complication rates due to minimal and visualizable bleeding and the elimination of pneumothorax risk. In lung transplant recipients, EBB may be obtained when TBB is too high-risk, including in the setting of acute lung allograft dysfunction (ALAD) requiring mechanical ventilation or in advanced chronic lung allograft dysfunction (CLAD). Most centers do not include EBB in post-transplant surveillance or for-cause bronchoscopy protocols, possibly due to a lack of a common histologic interpretation system. Previous work has demonstrated that lymphocytic inflammation in lung transplant EBB is associated with acute cellular rejection and future risk for CLAD, but these have not translated into subsequent studies on clinical utility or into clinical practice. Recent multicenter studies suggest that gene expression-based diagnostics leveraging EBB may outperform histologic grading and provide important prognostic utility in predicting graft loss. Herein, we will review what is known about the lung transplant mucosa including recent diagnostic advances and propose how EBB analyses could be incorporated into research studies and clinical workflows. We propose that mucosal sampling could provide safe, consistent, and informative data to improve patient outcomes after lung transplant.

The diagnosis and management of chronic lung allograft dysfunction

PURPOSE OF REVIEW

Chronic lung allograft dysfunction (CLAD) remains a life-threatening complication following lung transplantation. Different CLAD phenotypes have recently been defined, based on the combination of pulmonary function testing and chest computed tomography (CT) scanning and spurred renewed interests in differential diagnosis, risk factors and management of CLAD.

RECENT FINDINGS

Given their crucial importance in the differential diagnosis, we will discuss the latest development in assessing the pulmonary function and chest CT scan, but also their limitations in proper CLAD phenotyping, especially with regards to patients with baseline allograft dysfunction. Since no definitive treatment exists, it remains important to timely identify clinical risk factors, but also to assess the presence of specific patterns or biomarkers in tissue or in broncho alveolar lavage in relation to CLAD (phenotypes). We will provide a comprehensive overview of the latest advances in risk factors and biomarker research in CLAD. Lastly, we will also review novel preventive and curative treatment strategies for CLAD.

SUMMARY

Although this knowledge has significantly advanced the field of lung transplantation, more research is warranted because CLAD remains a life-threatening complication for all lung transplant recipients.

Immune aging: biological mechanisms, clinical symptoms, and management in lung transplant recipients

While chronologic age can be precisely defined, clinical manifestations of advanced age occur in different ways and at different rates across individuals. The observed phenotype of advanced age likely reflects a superposition of several biological aging mechanisms which have gained increasing attention as the world contends with an aging population. Even within the immune system, there are multiple age-associated biological mechanisms at play, including telomere dysfunction, epigenetic dysregulation, immune senescence programs, and mitochondrial dysfunction. These biological mechanisms have associated clinical syndromes, such as telomere dysfunction leading to short telomere syndrome (STS), and optimal patient management may require recognition of biologically based aging syndromes. Within the clinical context of lung transplantation, select immune aging mechanisms are particularly pronounced. Indeed, STS is increasingly recognized as an indication for lung transplantation. At the same time, common aging phenotypes may be evoked by the stress of transplantation because lung allografts face a potent immune response, necessitating higher levels of immune suppression and associated toxicities, relative to other solid organs. Age-associated conditions exacerbated by lung transplant include bone marrow suppression, herpes viral infections, liver cirrhosis, hypogammaglobulinemia, frailty, and cancer risk. This review aims to dissect the molecular mechanisms of immune aging and describe their clinical manifestations in the context of lung transplantation. While these mechanisms are more likely to manifest in the context of lung transplantation, this mechanism-based approach to clinical syndromes of immune aging has broad relevance to geriatric medicine.

Outcomes of lung transplantation in patients with telomere-related forms of progressive fibrosing interstitial lung disease pulmonary fibrosis: A systematic review

Background

Lung transplantation (LTX) is the last life-extending option for patients with progressive fibrosing interstitial lung diseases (fILD). Between 12% and 71% of patients with fILD are patients with underlying telomere-dysfunction (trILD) related to pathogenic telomere-related gene (TRG) variants and/or short telomere length. TrILD patients tend to have earlier disease onset, faster progression, and worse prognosis causing them to be referred for LTX more often. Regarding LTX outcomes in trILD, there are contradictory reports on patient and graft survival, as well as numerous other outcomes. There is no consensus on whether trILD is associated with poorer outcomes after LTX and what considerations regarding candidacy are appropriate.

Methods

We aimed to systematically review LTX outcomes of patients with trILD in comparison to those with non-trILD.

Results

A systematic literature search yielded 13 studies that met the inclusion criteria including 933 LTX, 281 in trILD, and 652 in non-trILD. Despite large heterogeneity in the methodological study quality and reported outcomes among the studies, patient and graft survival after LTX in trILD did not evidently seem inferior to LTX in non-trILD. However, there may be increased risk of specific complications, such as cytopenias, airway complications, and cytomegalovirus-reactivation.

Conclusions

In summary, due to large heterogeneity in methodological study quality and reported outcomes, no firm conclusions can be drawn. Patient and graft survival do not seem unequivocally inferior in patients with trILD deemed eligible for LTX. On top of limited available high-quality data, specific patient selection and post-transplant management strategies may affect the currently acquired results. As such, differences may exist regarding transplant-related outcomes, which could require special attention and consideration. Further high-quality comparative studies on LTX outcomes in trILD are needed to draw final conclusions and provide recommendations regarding patient selection and post-transplantation management.

Comparison of Prognosis for Lung Transplantation between Older and Younger Donors: A Systematic Review and Meta-Analysis Based on Cohort Studies

PURPOSE

This meta-analysis aimed to compare the prognosis of lung transplantation recipients based on donor age.

METHODS

A detailed search was performed in PubMed, Embase, Web of Science, and the Cochrane Library for cohort studies on lung transplantation. The prognosis of lung transplant recipients was investigated based on the donor age, with the primary outcomes being 1-year overall survival (OS), 3-year OS, 5-year OS, and 5-year chronic lung allograft dysfunction (CLAD)-free survival.

RESULTS

This meta-analysis included 10 cohort studies. Among the short-term outcomes, the older donor group demonstrated no significant difference from the young donor group in primary graft dysfunction within 72 hours, use of extracorporeal membrane oxygenation, length of ventilator use, and intensive care unit hours. However, a longer hospital stay was associated with the older donor group. In terms of long-term outcomes, no difference was found between the two groups in 1-year OS, 3-year OS, and 5-year OS. Notably, patients with older donors exhibited a superior 5-year CLAD-free survival.

CONCLUSIONS

The results of this meta-analysis indicate that older donors are not inferior to younger donors in terms of long-term and short-term recipient outcomes. Lung transplantation using older donors is a potential therapeutic option after rigorous evaluation.