Management of nontuberculous mycobacterial in lung transplant cases: an international delphi study

Rationale

Nontuberculous Mycobacterial (NTM) diseases are difficult to treat infections, especially in lung transplant (LTx) candidates. Currently, there are paucity of recommendations on the management of NTM infections in LTx, focusing on Mycobacterium avium complex (MAC), M.abscessus(MAB), and M.kansasii(MK).

Methods

Pulmonologists, infectious disease specialists, LTx surgeons, and Delphi experts with expertise in NTM were recruited. A patient representative was also invited. Three questionnaires were distributed to panelists comprising of questions with multiple response statements. Delphi methodology with a Likert scale of 11 points (5 to −5) was applied to define the agreement between experts. Responses from the first two questionnaires were collated to develop a final questionnaire. The consensus was described as a median rating >4 or <- four indicating for or against the given statement. After the last round of questionnaires, a cumulative report was generated.

Results

Panelists recommend performing sputum cultures and a chest CT scan for NTM screening in lung transplant candidates. Panelists recommend against absolute contraindication to LTx even with multiple positive sputum cultures for MAC, M.abscessus,or M.kansasii.Panelists recommend MAC patients on antimicrobial treatment and culture harmful can be listed for LTx without further delay. Panelists recommend six months of culture-negative for M.kansasii, whereas a 12-month further treatment from the time of culture-negative for M.abscessusbefore listing for LTx.

Conclusion

NTM LTx study consensus statement has provided essential recommendations in NTM management in LTx and can be utilized as an expert opinion while awaiting evidence-based contributions.

Resolution of post-lung transplant ischemia-reperfusion injury is modulated via Resolvin D1-FPR2 and Maresin 1-LGR6 signaling

BACKGROUND

Dysregulation of inflammation-resolution pathways leads to postlung transplant (LTx) ischemia-reperfusion (IR) injury and allograft dysfunction. Our hypothesis is that combined treatment with specialized pro-resolving lipid mediators, that is, Resolvin D1 (RvD1) and Maresin-1 (MaR1), enhances inflammation-resolution of lung IR injury.

METHODS

Expression of RvD1 and MaR1 was analyzed in bronchoalveolar lavage (BAL) fluid of patients on days 0, 1, and 7 post-LTx. Lung IR injury was evaluated in C57BL/6 (WT), FPR2^-/-, and LGR6 siRNA treated mice using a hilar-ligation model with or without administration with RvD1 and/or MaR1. A donation after circulatory death and murine orthotopic lung transplantation model was used to evaluate the protection by RvD1 and MaR1 against lung IR injury. In vitro studies analyzed alveolar macrophages and type II epithelial cell activation after treatment with RvD1 or MaR1.

RESULTS

RvD1 and MaR1 expressions in BAL from post-LTx patients was significantly increased on day 7 compared to days 0 and 1. Concomitant RvD1 and MaR1 treatment significantly mitigated early pulmonary inflammation and lung IR injury in WT mice, which was regulated via FPR2 and LGR6 receptors. In the murine orthotopic donation after cardiac death LTx model, RvD1 and MaR1 treatments significantly attenuated lung IR injury and increased PaO₂ levels compared to saline-treated controls. Mechanistically, RvD1/FPR2 signaling on alveolar macrophages attenuated HMGB1 and TNF-α secretion and upregulated uptake of macrophage-dependent apoptotic neutrophils (efferocytosis), whereas MaR1/LGR6 signaling mitigated CXCL1 secretion by epithelial cells.

CONCLUSIONS

Bioactive proresolving lipid mediator-dependent signaling that is, RvD1/FPR2 and MaR1/LGR6- offers a novel therapeutic strategy in post-LTx injury.

Set Up for Failure: Pre-Existing Autoantibodies in Lung Transplant

Lung transplant patients have the lowest long-term survival rates compared to other solid organ transplants. The complications after lung transplantation such as primary graft dysfunction (PGD) and ultimately chronic lung allograft dysfunction (CLAD) are the main reasons for this limited survival. In recent years, lung-specific autoantibodies that recognize non-HLA antigens have been hypothesized to contribute to graft injury and have been correlated with PGD, CLAD, and survival. Mounting evidence suggests that autoantibodies can develop during pulmonary disease progression before lung transplant, termed pre-existing autoantibodies, and may participate in allograft injury after transplantation. In this review, we summarize what is known about pulmonary disease autoantibodies, the relationship between pre-existing autoantibodies and lung transplantation, and potential mechanisms through which pre-existing autoantibodies contribute to graft injury and rejection.

A novel injury site-natural antibody targeted complement inhibitor protects against lung transplant injury

Complement is known to play a role in ischemia and reperfusion injury (IRI). A general paradigm is that complement is activated by self-reactive natural IgM antibodies (nAbs), after they engage postischemic neoepitopes. However, a role for nAbs in lung transplantation (LTx) has not been explored. Using mouse models of LTx, we investigated the role of two postischemic neoepitopes, modified annexin IV (B4) and a subset of phospholipids (C2), in LTx. Antibody deficient Rag1-/- recipient mice were protected from LTx IRI. Reconstitution with either B4 or C2nAb restored IRI, with C2 significantly more effective than B4 nAb. Based on these information, we developed/characterized a novel complement inhibitor composed of single-chain antibody (scFv) derived from the C2 nAb linked to Crry (C2scFv-Crry), a murine inhibitor of C3 activation. Using an allogeneic LTx, in which recipients contain a full nAb repertoire, C2scFv-Crry targeted to the LTx, inhibited IRI, and delayed acute rejection. Finally, we demonstrate the expression of the C2 neoepitope in human donor lungs, highlighting the translational potential of this approach.

Macrophage activating syndrome causing decompensated right heart failure

Background

Macrophage activating syndrome (MAS) is a form of hemophagocytic lymphohistiocytosis (HLH), a rare complication of autoimmune disease that is characterized by cytokine storm and multiorgan failure.

Case summary

A 32-year-old male presented with acutely decompensated pulmonary arterial hypertension and right heart failure secondary to MAS. The patient was immediately started on inhaled and intravenous epoprostenol, vasopressors and dexamethasone and anakinra were administered. Despite the therapies given, the patient's condition continued to decline, and he was placed on veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support. Over a few days, his clinical condition improved, and he was decannulated from VA-ECMO and later transitioned oral treprositinil and was discharged home. Due to its non-specific clinical manifestations, the diagnosis of MAS depends on high clinical suspicion and initial laboratory work up such as thrombocytopenia, transaminitis, hyperferritinemia, hypertriglyceridemia, hypofibrinogenemia, etc. In our patient, MAS led to decompensated Pulmonary Arterial Hypertension (PAH) leading to right heart failure that was refractory to inhaled and intravenous epoprostenol and vasopressors and required VA-ECMO as a bridge to recovery while his MAS was managed by anakinra and dexamethasone.

Conclusion

MAS can result in acute decompensation of PAH and right heart failure. Besides RV failure management, immunosuppressants such as anakinra, etoposide, etc. should be utilized early in the management of MAS. In refractory right heart failure, VA-ECMO can be considered as a bridge to recovery. There is a paucity of literature supporting the utilization of VA-ECMO in the management of refractory right heart failure caused by MAS in adults and much of the data stems from pediatric studies. This case serves as a fine example of successful use of VA-ECMO in adult population.

MicroRNA-206 antagomiR‒enriched extracellular vesicles attenuate lung ischemia‒reperfusion injury through CXCL1 regulation in alveolar epithelial cells

BACKGROUND

Our hypothesis is that the immunomodulatory capacities of mesenchymal stem cell‒derived extracellular vesicles (EVs) can be enhanced by specific microRNAs (miRNAs) to effectively attenuate post-transplant lung ischemia‒reperfusion (IR) injury.

METHODS

The expression of miR-206 was analyzed in bronchoalveolar lavage (BAL) fluid of patients on Days 0 and 1 after lung transplantation. Lung IR injury was evaluated in C57BL/6 mice using a left lung hilar-ligation model with or without treatment with EVs or antagomiR-206‒enriched EVs. Murine lung tissue was used for miRNA microarray hybridization analysis, and cytokine expression, lung injury, and edema were evaluated. A donation after circulatory death and murine orthotopic lung transplantation model was used to evaluate the protection by enriched EVs against lung IR injury. In vitro studies analyzed type II epithelial cell activation after coculturing with EVs.

RESULTS

A significant upregulation of miR-206 was observed in the BAL fluid of patients on Day 1 after lung transplantation compared with Day 0 and in murine lungs after IR injury compared with sham. Treatment with antagomiR-206‒enriched EVs attenuated lung dysfunction, injury, and edema compared with treatment with EVs alone after murine lung IR injury. Enriched EVs reduced lung injury and neutrophil infiltration as well as improved allograft oxygenation after murine orthotopic lung transplantation. Enriched EVs significantly decreased proinflammatory cytokines, especially epithelial cell‒dependent CXCL1 expression, in the in vivo and in vitro IR injury models.

CONCLUSIONS

EVs can be used as biomimetic nanovehicles for protective immunomodulation by enriching them with antagomiR-206 to mitigate epithelial cell activation and neutrophil infiltration in the lungs after IR injury.

International Society for Heart and Lung Transplantation consensus statement for the standardization of bronchoalveolar lavage in lung transplantation

Bronchoalveolar lavage (BAL) is a key clinical and research tool in lung transplantation (LTx). However, BAL collection and processing are not standardized across LTx centers. This International Society for Heart and Lung Transplantation-supported consensus document on BAL standardization aims to clarify definitions and propose common approaches to improve clinical and research practice standards. The following 9 areas are covered: (1) bronchoscopy procedure and BAL collection, (2) sample handling, (3) sample processing for microbiology, (4) cytology, (5) research, (6) microbiome, (7) sample inventory/tracking, (8) donor bronchoscopy, and (9) pediatric considerations. This consensus document aims to harmonize clinical and research practices for BAL collection and processing in LTx. The overarching goal is to enhance standardization and multicenter collaboration within the international LTx community and enable improvement and development of new BAL-based diagnostics.

1136. Universal Prophylaxis for Prevention of Invasive Aspergillus in Lung Transplant Recipients

Background

Invasive aspergillosis (IA) is a significant complication status post lung transplantation with an incidence of 6% to 16%. Because early diagnosis of IA in lung transplant is hampered by the lack of specific clinical signs and by the low sensitivity of culture-based diagnostic methods, the efficacy of bronchoalveolar lavage galactomannan (BAL GM) for early diagnosis is explored in this study.

Methods

A retrospective analysis was performed on 45 consecutive lung transplant recipients between January 2015 and February 2016 at UF Health Shands Hospital. All patients were placed on prophylactic itraconazole post-transplant. Surveillance bronchoscopies were performed at 2 weeks, 1 month, 3 months, 6 months, 9 months, and 12 months post-transplant. During each bronchoscopy, bacterial, fungal, and acid-fast bacterial cultures along with BAL GM [an optical density (OD) index of ≥0.5 considered positive] were obtained. If BAL GM ≥1.0, the patient was switched to voriconazole for further treatment. CT Chest was also evaluated. If BAL GM remained ≤1.0 at the 6 month interval, then prophylaxis was complete. IA was defined using the EORTC/MSG criteria for invasive fungal disease (i.e., patient classified as either having proven, probable or possible IA).

Results

There was a total of 225 observations from the 45 patients. Two patients (4.4%) had proven IA with a mean GM of 4.153 (SE, 0.629) and seven patients (15%) had probable IA with a mean of 2.169 (SE, 0.409). There was no correlation of cold ischemic time (P = 0.88), primary graft dysfunction (PGD, P = 0.38), presence of Candida species (P =0.048) or non-tuberculous mycobacteria (NTM) in bronchoalveolar lavage (P = 0.044), and viral pneumonitis (P = 0.047) with a positive BAL GM. All nine patients with GM &gt;1 were switched to voriconazole from itraconazole which resulted in negative GM levels on follow-up bronchoscopy.

Conclusion

Our data suggest that the implementation of universal antifungal prophylaxis with itraconazole may not be efficacious in preventing IA in lung transplant recipients. On the other hand, surveillance with BAL GM is a strategy that can lead to early detection of IA in patients during the first year after lung transplantation.

Disclosures

All authors: No reported disclosures.