Loss of IGFBP2 mediates alveolar type 2 cell senescence and promotes lung fibrosis

Accumulation of senescent cells contributes to age-related diseases including idiopathic pulmonary fibrosis (IPF). Insulin-like growth factor binding proteins (IGFBPs) regulate many biological processes; however, the functional contributions of IGFBP2 in lung fibrosis remain largely unclear. Here, we report that intranasal delivery of recombinant IGFBP2 protects aged mice from weight loss and demonstrated antifibrotic effects after bleomycin lung injury. Notably, aged human-Igfbp2 transgenic mice reveal reduced senescence and senescent-associated secretory phenotype factors in alveolar epithelial type 2 (AEC2) cells and they ameliorated bleomycin-induced lung fibrosis. Finally, we demonstrate that IGFBP2 expression is significantly suppressed in AEC2 cells isolated from fibrotic lung regions of patients with IPF and/or pulmonary hypertension compared with patients with hypersensitivity pneumonitis and/or chronic obstructive pulmonary disease. Altogether, our study provides insights into how IGFBP2 regulates AEC2-cell-specific senescence and that restoring IGFBP2 levels in fibrotic lungs can prove effective for patients with IPF.

Antireflux surgery versus medical management of gastro-oesophageal reflux after lung transplantation

OBJECTIVES

Gastro-oesophageal reflux disease after lung transplantation may be associated with chronic lung allograft dysfunction. Aspiration may continue on medical management of reflux, but antireflux surgery potentially reduces all reflux. We compared outcomes between medical and surgical management of reflux in lung recipients.

METHODS

Lung recipients with an elevated DeMeester score (≥14.72) on post-transplant reflux testing between 2015 and 2020 were included. Patients were divided into 2 groups: group A (underwent surgery) and group B (medically managed). Endpoints were pulmonary function, allograft dysfunction-free survival and overall survival. Further analysis included subgroups: A1 (early surgery, <6 months) and A2 (late surgery, >6 months), and B1 (DeMeester <29.9) and B2 (DeMeester ≥30).

RESULTS

A total of 186 included subjects were divided into groups A [n = 46 (A1, n = 36; A2, n = 10)] and B [n = 140 (B1, n = 78; B2, n = 62)]. Compared to medically managed patients, patients who underwent surgery had a higher prevalence of hiatal hernia (P < 0.001) and a lower prevalence of oesophageal motility disorders (P = 0.036). Recipients who underwent surgery had superior pulmonary function at 5 years compared to group B (P < 0.05) and longer allograft dysfunction-free survival than subgroup B2 (P = 0.028). Furthermore, early surgery was associated with longer survival than late surgery (P = 0.021).

CONCLUSIONS

Antireflux surgery in recipients with reflux improved long-term allograft function, and early surgery showed a survival benefit. Allograft dysfunction-free survival of lung recipients who underwent surgery was significantly better than that of medically managed patients with DeMeester ≥30. We present an algorithm for appropriate selection of candidates for antireflux surgery after lung transplantation.

Hospitalized patients with irreversible lung injury from COVID-19 have higher morbidity but similar 1-year survival after lung transplant compared to hospitalized patients transplanted for restrictive lung disease

BACKGROUND

Hospitalized lung transplant (LT) recipients (LTRs) have higher post-LT morbidity and mortality than those who are well enough to wait for transplant at home. Outcomes after LT for COVID-19-associated acute respiratory distress syndrome (CARDS) may be even worse; thus, we compared post-LT outcomes between hospitalized LTRs transplanted for CARDS and those transplanted for restrictive lung disease (RLD).

METHODS

Between 2014 and 2021, hospitalized LTRs ≥18 years old with CARDS or RLD were included. Primary and secondary outcomes were 1-year post-LT survival and postoperative morbidity. For each patient in the CARDS group, an analysis of 1-to-1 matched patients from the RLD group was performed using logistic regression modeling.

RESULTS

Of 764 LTRs, 163 (21.3%) were hospitalized at the time of LT; 132 met the inclusion criteria: 11 (8.3%) were transplanted for CARDS and 121 (91.7%) for RLD. LTRs with CARDS were younger with longer pre-LT hospitalization stays and higher rates of pretransplant mechanical ventilation, dialysis, and ECMO as a bridge to transplant. A propensity-matched analysis demonstrated comparable rates of intrathoracic adhesions, posttransplant duration of mechanical ventilation, PGD3 at 72 hours, and delayed chest closure. Compared to LTRs with RLD, those with CARDS had significantly longer posttransplant hospital stays and a higher prevalence of ACR ≥A2 and DSA >2000 MFI, but comparable 1-year survival rates.

CONCLUSION

Even with careful selection, LT for patients with CARDS was associated with significant morbidity; however, 1-year survival of recipients with CARDS was comparable to that of matched hospitalized recipients with RLD.

Association Between Antibodies Against Lung Self-Antigens and Gastroesophageal Reflux in Lung Transplant Candidates

Gastroesophageal reflux (GER) and pretransplant antibodies against lung self-antigens (SAbs) collagen-V and/or k-alpha 1 tubulin are both independently associated with allograft dysfunction after lung transplantation (LTx). The role of GER in inducing lung injury and SAbs is unknown. We aimed to study the association between pre-LTx GER and SAbs. After IRB approval, we retrieved SAb assays conducted between 2015 and 2019 and collected 24 hour GER data for these patients. Patients were divided into 2 groups: no reflux (GER-) and pathologic reflux (GER+) to compare the prevalence of SAbs. Multivariate analysis was used to study the association between GER and SAbs in the whole cohort and in restrictive lung disease (RLD) and obstructive lung disease (OLD) subsets. Proximal esophageal reflux (PER) events ≥5 was considered abnormal. Patients (n = 134; 73 men) were divided into groups: GER- (54.5%, n = 73) and GER+ (45.5%, n = 61). The prevalence of GER was higher in the RLD than in the OLD subset (p < 0.001). The overall prevalence of SAbs was 53.7% (n = 72), higher in the GER+ than the GER- group (65.6% vs 43.8%, p = 0.012), but comparable between RLD and OLD subsets. Overall, SAbs were associated with GER (p = 0.012) and abnormal PER (p = 0.017). GER and abnormal PER increased the odds of SAbs in the RLD subset (OR [95% CI]: 2.825 [1.033-7.725], p = 0.040 and OR [95% CI]: 3.551 [1.271-9.925], p = 0.014, respectively) but not in the OLD subset. LTx candidates have a high prevalence of SAbs, which are significantly associated with GER and abnormal PER in patients with RLD.

Morbidity of antireflux surgery in lung transplant and matched nontransplant cohorts is comparable

BACKGROUND

Safety data on perioperative outcomes of laparoscopic antireflux surgery (LARS) after lung transplantation (LT) are lacking. We compared the 30-day readmission rate and short-term morbidity after LARS between LT recipients and matched nontransplant (NT) controls.

METHODS

Adult patients who underwent LARS between January 1, 2015, and October 31, 2021, were included. The participants were divided into two groups: LT recipients and NT controls. First, we compared 30-day readmission rates after LARS between the LT and NT cohorts. Next, we compared 30-day morbidity after LARS between the LT cohort and a 1-to-2 propensity score-matched NT cohort.

RESULTS

A total of 1328 patients (55 LT recipients and 1273 NT controls) were included. The post-LARS 30-day readmission rate was higher in LT recipients than in the overall NT controls (14.5% vs. 2.8%, p < 0.001). Compared to matched NT controls, LT recipients had a lower prevalence of paraesophageal hernia, a smaller median hernia size, and higher peristaltic vigor. Also compared to the matched NT controls, the LT recipients had a lower median operative time but a longer median length of hospital stay. The proportion of patients with a post-LARS event within 30 postoperative days was comparable between the LT and matched NT cohorts (21.8% vs 14.5%, p = 0.24).

CONCLUSIONS

Despite a higher perceived risk of comorbidity burden, LT recipients and matched NT controls had similar rates of post-LARS 30-day morbidity at our large-volume center with expertise in transplant and foregut surgery. LARS after LT is safe.

Incidentally Detected Malignancies in Lung Explants

Introduction: Incidentally detected malignancies in lung explants portend risk of early cancer recurrence and metastases with posttransplant immunosuppression. We present a series of lung transplant recipients with previously unverified malignancies in native lung explants. Design: We reviewed the histopathology, radiographic imaging, and management of lung explant malignancies at our institution over 10 years (2011-2020). Endpoints were survival and allograft rejection. Results: An explant malignancy was found in 1.3% (11/855) of lung transplant recipients (6 [55%] men; median age 68 years; 6 [55%] ex-smokers [median pack-years, 25]). Nine (82%) were adenocarcinoma, 1 (9%) was squamous cell carcinoma (SCC), and 1 (9%) was follicular lymphoma. Three patients (27%) had multifocal involvement (≥3 lobes), 4 (36%) had nodal involvement, and the median (range) tumor size was 2.7 (0.4-19) cm. The median interval between last imaging and transplant was 58 (29-144) days. Mycophenolate mofetil was discontinued or reduced in all; everolimus was used in 2 patients, and cisplatin-pemetrexed chemotherapy was used in 2 patients. The prevalence of acute cellular rejection and chronic rejection was 27% and 9%, respectively. Lung recipients with cancer had significantly lower survival than those without (36.4% vs 67.3%, p = 0.002); median survival was 27 (17, 65) months in 4 recipients who were alive and cancer-free at the end of the study period. Conclusions: Unidentified malignancies, commonly adenocarcinoma, can be detected in explanted native lungs. Pneumonectomy may be curative in SCC, lymphoproliferative disorders, and stage I adenocarcinoma. Modulating immunosuppression to prevent allograft rejection and tumor proliferation is warranted.

Unravelling a novel, promising and convenient tool for differential diagnosis of delayed puberty: GnRHa-stimulated inhibin B (GnRH-iB)

BACKGROUND

Etiological diagnosis of delayed puberty is difficult. Despite availability of various basal and stimulation tests differentiation between constitutional delay in puberty and hypogonadotropic hypogonadism is still challenging.

OBJECTIVE

To elucidate the role of GnRH agonist-stimulated inhibin B (GnRH-iB) for the differential diagnosis of delayed puberty.

STUDY DESIGN

Participants were recruited into "exploratory cohort" (n = 39) and "validation cohort" (n = 16). "Exploratory cohort" included children with spontaneous puberty and patients with hypogonadotropic hypogonadism. "Validation cohort" constituted children who presented with delayed puberty.

INTERVENTION AND OUTCOME

GnRHa (Triptorelin) stimulation test along with measurement of inhibin B level at 24 h after GnRHa injection was performed in all the study participants. Cut-offs for GnRH-iB were derived from the "exploratory cohort". These cut-offs were applied to the "validation cohort". Basal LH, basal inhibin B(INH-B), GnRHa-stimulated LH at 4 h (GnRH-LH) and GnRH-iB were evaluated for the prediction of onset of puberty on prospective follow-up.

RESULTS

GnRH-iB at a cut-off value of 113.5 pg/ml in boys and 72.6 pg/ml in girls had 100% sensitivity and specificity for the documentation of puberty. In the "validation cohort" basal LH, basal INH-B, GnRH-LH, and GnRH-iB had a diagnostic accuracy of 68.75%, 81.25%, 68.75% and 93.75% respectively, for the prediction of onset of puberty. Basal LH, basal INH-B and GnRH-LH used alone or in combination were inferior to GnRH-iB used alone.

CONCLUSION

GnRHa-stimulated inhibin B (GnRH-iB) is a convenient and easily employable test for the differentiation of constitutional delay in puberty from hypogonadotropic hypogonadism.

CTRI REGISTRATION NO

CTRI/2019/10/021570.

Exploring optimal multimode vibronic pathways in singlet fission of azaborine analogues of perylene

The development of new singlet fission chromophores is a vibrant area of research to explore the possibility of efficient photovoltaic devices. Using high-level ab-initio density matrix renormalization group calculations, we present a systematic analysis of BN-doped perylenes for their potential application as singlet fission candidates. Four singlet fission chromophores are identified considering the monomer-based properties and their excitonic characters are further analyzed in a dimer configuration optimized in a six-dimensional space for local maxima of fission rates. Furthermore, a multistate multimode vibronic Hamiltonian is employed to identify intra- and interstate vibrational pathways for excitation energy modulation. Several photophysical properties such as Davydov splitting, activation energy and vibronic admixture of multiexcitonic and charge-transfer states are calculated for physically accessible dimers. The optimal dimer packing results in appropriate vibrational relaxation of singlet fission states and promotes significant population transfer which would be more attenuated without such couplings. This work not only identifies potential singlet fission systems with favorable electronic properties but also highlights the sensitivity of dimer packings with respect to the substitution patterns in singlet fission chromophores.

Universal Lifelong Fungal Prophylaxis and Risk of Coccidioidomycosis in Lung Transplant Recipients Living in an Endemic Area

BACKGROUND

Lung transplant recipients residing in the endemic region are vulnerable to severe morbidity and mortality from Coccidioides. As infection risk persists beyond the first posttransplant year, investigations evaluating extended prophylaxis durations are needed. The purpose of this study is to assess the incidence of coccidioidomycosis among lung transplant recipients receiving universal lifelong azole antifungal prophylaxis.

METHODS

Patients receiving transplants from 2013-2018 and initiated on azole antifungal prophylaxis at a lung transplant center in Arizona were included and followed through 2019 or until death, second transplant, or loss to follow-up. Recipients who died or received treatment for coccidioidomycosis during the transplant admission, or who had received a previous transplant, were excluded. The primary outcome was proven or probable coccidioidomycosis with new asymptomatic seropositivity assessed secondarily.

RESULTS

A total of 493 lung transplant recipients were included, with 82% initiated on itraconazole prophylaxis, 9.3% on voriconazole, and 8.5% on posaconazole. Mean age at transplant was 62 years, 77% were diabetic, and 8% were seropositive for Coccidioides pretransplant. After a median follow-up of 31 months, 1 proven infection and 1 case of new asymptomatic seropositivity (1/493 each, 0.2% incidence) occurred during the study period. The single coccidioidomycosis case occurred 5 years posttransplant in a patient who had azole prophylaxis stopped several months prior. Although within-class switches were common throughout the study period, permanent discontinuation of azole prophylaxis was rare (1.4% at end of follow-up).

CONCLUSIONS

Universal lifelong azole prophylaxis was associated with a low rate of coccidioidomycosis among lung transplant recipients residing in endemic regions.

Management of the Potential Lung Donor

The use of donor management protocols has significantly improved recovery rates; however, the inherent instability of lungs after death results in low utilization rates of potential donor lungs. Donor lungs are susceptible to direct trauma, aspiration, neurogenic edema, ventilator-associated barotrauma, and ventilator-associated pneumonia. After irreversible brain injury and determination of futility of care, the goal of medical management of the donor shifts to maintaining hemodynamic stability and maximizing the likelihood of successful organ recovery.

Lung Transplantation for COVID-19-Induced Respiratory Failure: Single-Center Case Series

Purpose

Prior to the COVID-19 (C19) pandemic, adult respiratory distress syndrome (ARDS) was an unusual indication for lung transplant (LT); thus, short- and long-term outcomes data are lacking. As the pandemic continues, there is an increased need for post-LT data. Thus, we report our single-center experience transplanting 11 patients for C19 ARDS.

Methods

We conducted a chart review of LT recipients (LTRs) transplanted for C19 ARDS between 8/1/21 and 7/31/21. Descriptive statistics were used.

Results

Most LTRs were male (82%, n=9). The median age at LT, body mass index, and lung allocation score were 47 (43, 54) years, 28.9 (26, 30) kg/m2, and 84.5 (60, 88), respectively. The median interval from initial hospitalization to listing and listing to LT was 119 (97, 124) and 5 (4, 11) days, respectively. Pretransplant COVID-related morbidities included venous thromboembolism (55%, n=6), hemorrhage requiring transfusion (36%, n=4), pneumothorax (55%, n=6), bacterial pneumonia (82%, n=9), bacteremia (45%, n=5), fungemia (36%, n=4), renal failure requiring renal replacement therapy (RRT; 9%, n=1), cerebrovascular event (9%, n=1), and musculoskeletal weakness (100%, n=11). Most patients required mechanical ventilation (91%, n=10), and 55% (n=6) were intubated at the time of LT. Furthermore, most patients required ECMO support (73%, n=8) and 36% (n=4) were on ECMO at the time of LT. Intraoperatively, 64% (n=7) of patients required cardiopulmonary bypass, 73% (n=8) had severe intrathoracic adhesions, 73% (n=8) had delayed chest closure, and 18% (n=2) had an unexpected return to the operating room. Prevalence of primary graft dysfunction grade 2 or 3 at 72 hours was high (91%, n=10), median duration of mechanical ventilation after LT was 10 (6, 19) days, but no one required ECMO rescue. To date, 10 (91%) LTRs have been discharged, and 2 (20%) have been readmitted within 30 days; the median post-LT hospital stay was 18 (14, 24) days; all discharged LTRs required acute rehabilitation for a median of 17.5 (14, 23) days. Ten LTRs (91%) at a median of 208 (167, 245) days post-LT; 1 LTR died 344 days post-LT of treatment-refractory allograft failure due to aspiration and antibody-mediated rejection.

Conclusion

Despite pre-LT critical illness, intraoperative challenges, and prolonged post-LT recovery, LT appears feasible for carefully selected patients with irreversible C19 ARDS.

A Comparison of Short-Term Morbidity and Mortality Among Inpatient Lung Transplant Recipients Transplanted for COVID-19 and Other Restrictive Lung Diseases

Purpose

Patients with respiratory failure (RF) who are hospitalized at the time of lung transplant (LTx) have higher post-LTx morbidity and mortality than those who are well enough to remain at home. Complications may be even worse in patients transplanted for COVID-19 (C19), as they are commonly critically ill having endured prolonged mechanical ventilation, ECMO support, myopathy, malnutrition, and superimposed infections. In a retrospective cohort study, we compared inpatient lung transplant recipients (LTxRs) transplanted for C19 vs. other underlying restrictive lung diseases (RLDs)

Methods

After IRB approval, patients who underwent inpatient LTx between 1/1/2014 and 8/31/2021 were categorized by indication: C19 or RLD. We excluded LTxRs <18 years old, a primary indication for LTx other than UNOS disease group D, and redo LTx. Primary outcomes were postoperative morbidity and 90-day survival.

Results

Out of 163 inpatient LTxRs, 141 met inclusion criteria: 11 (7.8%) with C19 and 130 (92.2%) with RLD. LTxRs with C19 were younger, had a longer pre-LTx hospital stay, and more likely needed pre-LTx mechanical ventilation and ECMO support. LTxRs with C19 were also more likely to have severe adhesions intraoperatively and their chest was more commonly left open after LTx due to a perceived risk of ongoing bleeding. In addition, LTxRs with C19 had a higher prevalence of PGD3 at 72 hours and longer post-LTx hospital stays and trended toward longer post-LTx mechanical ventilation and need for inpatient rehabilitation. The 2 groups had similar 90-day survival (C19, 100% vs. RLD, 95.4%, p=0.472), however, LTxRs with C19 had a higher incidence of acute cellular rejection and DSA production (>2,000 MFI) within 6 months of transplant.

Conclusion

LTxRs with C19 are typically sicker and have more post-LTx complications than LTxRs with RLD hospitalized at the time of LTx. However, 90-day survival is comparable and high in both groups. Long-term follow-up is needed.

Novel role for tumor suppressor gene, liver kinase B1, in epithelial-mesenchymal transition leading to chronic lung allograft dysfunction

Epithelial-mesenchymal transition (EMT) has been implicated to play a role in chronic lung allograft dysfunction (CLAD). Liver kinase B1 (LKB1), a tumor suppressor gene, can regulate EMT. However, its role in CLAD development following lung transplantation remains unknown. Using qRT-PCR, biopsies from lung transplant recipients with bronchiolitis obliterans syndrome (BOS) demonstrated significant downregulation of LKB1 (p = .0001), compared to stable biopsies. To determine the role of LKB1 in EMT development, we analyzed EMT in human bronchial epithelial cell line BEAS-2B. Knockdown of LKB1 by siRNA significantly dysregulated mesenchymal markers expression in BEAS-2B cells. Following incubation of human primary bronchial epithelial cell or BEAS-2B cells with exosomes isolated from BOS or stable lung transplant recipients, LKB1 expression was inhibited when incubated with BOS-exosome. Incubation with BOS-exosomes also decreased LKB1 expression and induced EMT markers in air-liquid interface culture method. Our results provide novel evidence that exosomes released from transplanted lungs undergoing chronic rejection are associated with inactivated tumor suppressor gene LKB1 and this loss induces EMT leading to the pathogenesis of CLAD following human lung transplantation.

Lung Transplant Candidates With Pretransplant Gastroesophageal Reflux and Antibodies to Lung Self-antigens Have Shorter CLAD-free Survival After Transplant

Pre–lung transplant (LTx) gastroesophageal reflux (GER) and circulating antibodies against the lung self-antigens (SAbs) collagen V and K-alpha-1 tubulin may predispose recipients to chronic lung allograft dysfunction (CLAD). We aimed to study the association of pre-LTx GER or pre-LTx SAbs with CLAD.

Current trends in candidate selection, contraindications, and indications for lung transplantation

Lung transplantation is an established treatment option that can improve quality of life and prolong survival for select patients diagnosed with end-stage lung disease. Given the gaps in organ donation and failures to make effective use of available organs, careful selection of candidates for lung transplant remains one of the most important considerations of the transplant community. Toward this end, we briefly reviewed recent trends in pretransplant evaluation, candidate selection, organ allocation, and organ preservation techniques. Since the latest consensus statement regarding appropriate selection of lung transplant candidates, many advances in the science and practice of lung transplantation have emerged and influenced our perspective of ‘contraindications’ to transplant. These advances have made it increasingly possible to pursue lung transplant in patients with risk factors for decreased survival—namely, older recipient age, increased body mass index, previous chest surgery, poorer nutritional status, and presence of chronic infection, cardiovascular disease, or extrapulmonary comorbid conditions. Therefore, we reviewed the updated evidence demonstrating the prognostic impact of these risk factors in lung transplant recipients. Lastly, we reviewed the salient evidence for current trends in disease-specific indications for lung transplantation, such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cystic fibrosis, emphysema due to alpha-1 antitrypsin deficiency, and pulmonary arterial hypertension, among other less common end-stage diseases. Overall, lung transplant remains an exciting field with considerable hope for patients as they experience remarkable improvements in quality of life and survival in the modern era.

Towards multistate multimode landscapes in singlet fission of pentacene: the dual role of charge-transfer states

Singlet fission duplicates triplet excitons for improving light harvesting efficiency. The presence of the interaction between electronic and nuclear degrees of freedom complicates the interpretation of correlated triplet pairs. We report a quantum chemistry study on the significance and subtleties of multistate and multimode pathways in forming triplet pair states of the pentacene dimer through a six-state vibronic-coupling Hamiltonian derived from many-electron adiabatic wavefunctions of an ab initio density matrix renormalization group. The resulting spin values of the singlet manifolds on each pentacene center are computed, and the varying spin nature can be distinguished clearly with respect to dimer stacking and vibronic progression. Our monomer spin assignments reveal the coexistence of both lower-lying weak and higher-lying strong charge transfer states which interact vibronically with the triplet pair state, providing important implications for its generation and separation occurring in vibronic regions. This work conveys the importance of the many-electron process requiring close low-lying singlet manifolds to determine the subtle fission details, and represents an important step for understanding vibronically resolved spin states and conversions underlying efficient singlet fission.

Outcomes after lung transplantation in recipients aged 70 years or older

BACKGROUND

The proportion of lung transplant (LTx) recipients older than 70 years is increasing, thus we assessed long-term survival after LTx in this cohort relative to younger counterparts.

PATIENTS AND METHODS

We retrospectively reviewed charts of patients who underwent LTx between 2012 and 2016 at our center and divided patients by age: group A (<65 years), B (65-69 years), and C (≥70 years). Survival statistics were evaluated using the Kaplan-Meier method and Cox regression.

RESULTS

The study included 375 LTx recipients: 221 (58.9%) in group A, 109 (29.1%) in group B, and 45 (12.0%) in group C. Group C was mostly men (37/45 [82.2%]; P = 0.003) and had the highest mean serum creatinine at listing (P = 0.02). Survival at 1, 3, and 5 years after transplant in group A (93.2%, 70.1%, 58.8%) was significantly higher than group B (83.5%, 59.6%, 44.0%; P = 0.005, 0.028, 0.006, log-rank test) and was similar to group C (86.7%, 64.4%, 57.8%), although trended higher at 1 year (P = 0.139, 0.274, 0.489, log-rank test). Groups B and C had comparable survival at all time points.

CONCLUSIONS

Although survival decreased after age 65, long-term survival was comparable between LTx recipients aged 65-69 years and recipients ≥70 years.

Outcomes of nontuberculous mycobacteria isolation among lung transplant recipients: A matched case-control with retrospective cohort study

DISCLAIMER

In an effort to expedite the publication of articles , AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

Lung transplant recipients are at increased risk for acquiring nontuberculous mycobacteria (NTM), but the clinical significance of NTM isolation, particularly among patients not meeting guideline-endorsed diagnostic criteria for NTM pulmonary disease, is unclear.

METHODS

A case-control study of lung transplant recipients with culture-positive NTM infections treated at a large transplant center during a 7-year period (2013-2019) was performed.

RESULTS

Twenty-nine cases were matched 1:2 to non-NTM controls. The median time to NTM isolation was 10.7 months post transplant. Only 34.5% of all cases, and half of treated cases, met diagnostic criteria for NTM pulmonary infection. All-cause mortality at 12 months was numerically higher among NTM cases versus controls (20.7% vs 8.6%, P = 0.169); however, no deaths were attributed to NTM. No increase in the 12-month rate of acute rejection was observed (27.6% vs 36.2%, P = 0.477). Recent augmented immunosuppression was associated with increased odds of NTM isolation, while azithromycin prophylaxis was associated with reduced odds of isolation and was not associated with macrolide resistance. Both adverse events and actual or potential drug-drug interactions occurred in more than 90% of treated cases; these events included ocular toxicity, hearing loss, and supratherapeutic calcineurin inhibitor concentrations. Eight of the 14 treated cases (57.1%) required early antibiotic discontinuation due to adverse events or drug-drug interactions.

CONCLUSION

Among lung transplant recipients, most patients with NTM isolation did not meet guideline criteria for infection and had outcomes similar to non‒NTM-infected patients, which may reflect transient lung colonization by NTM rather than true disease. As adverse events are common with NTM therapy, limiting unnecessary antibiotic treatment represents an area for future antimicrobial stewardship efforts.