Emphysema-associated Autoreactive Antibodies Exacerbate Post-Lung Transplant Ischemia-Reperfusion Injury

Precision cut lung slices: an innovative tool for lung transplant research

Lung ischemia-reperfusion injury (IRI), a common complication after lung transplantation (LTx), plays a crucial role in both primary graft dysfunction (PGD) and chronic lung allograft dysfunction (CLAD) thereby adversely impacting the clinical outcomes in these patient cohorts. Lung IRI is characterized by several molecular events including immune cell infiltration, reactive oxygen species (ROS) generation, calcium overload, inflammation and various forms of cell death pathways. Currently, no therapeutic agents are available to clinically prevent lung IRI. While animal and cell culture models are highly valuable in understanding the pathophysiology of lung IRI, they may not completely recapitulate the complexity of human lung tissue pathology. This limitation necessitates the requirement for developing innovative preclinical human research tools that can supplement available scientific modalities. Emerging evidence suggests that precision-cut lung slices (PCLS) have become an indispensable tool in scientific research to study lung biology in an ex vivo tissue system. Recent studies using PCLS have investigated lung diseases including asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. Although PCLS can be successfully employed to determine the deleterious events in the pathogenesis of lung IRI, including cell-cell interactions as well as hallmarks of inflammation and oxidative stress-dependent pathways, detailed studies employing PCLS to decipher these molecular events in post-LTx injury are currently limited. This review focuses on the applicability and unexplored potential of PCLS as a powerful tool in lung IRI research for understanding the pathophysiology and consequent development of new therapeutic modalities.

Characteristics of Serum Autoantibody Repertoire and Immune Subgroup Variation of Tuberculosis-Associated Obstructive Pulmonary Disease

Background

Studying the potential etiology and pathogenesis of tuberculosis-associated chronic obstructive pulmonary disease (TOPD) from an autoimmunity perspective may provide insights into peripheral blood autoantibodies and immune cells, as well as their interactions.

Methods

This study examined the serum autoantibody repertoire in healthy individuals, patients with chronic obstructive pulmonary disease (COPD), patients with pulmonary tuberculosis (TB), and TOPD patients using the HuProtTM protein chip. Autoantigens in the peripheral blood of TOPD patients were verified using ELISA assay. Various epitopes and immune simulation were predicted using bioinformatic methods. Flow cytometry was employed to detect macrophages(Mφ), T cells, and innate lymphoid cells (ILCs) in the peripheral blood.

Results

COPD patients displayed distinct alterations in their IgG and IgM autoantibodies compared to the other groups. GeneOntology (GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG)analyses revealed that these autoantibodies were associated with regulating macrophages, T cells, and B cells. ELISA results confirmed the upregulation of expression of proliferating cell nuclear antigen (PCNA), Mitogen-Activated Protein Kinase 3 antigen (MAPK3), and threonine protein kinase 1 antigen (AKT1) proteins in the peripheral blood of TOPD patients. Bioinformatic analysis predicted multiple potential epitopes in Th, CTL, and B cells. Immune simulation results demonstrated that PCNA, MAPK3, and AKT1 can activate innate and adaptive immune responses and induce the expression of different cytokines, such as IFN-g and IL-2. Furthermore, data obtained from flow cytometry assay revealed an upregulation in the face of Th1 cells in the peripheral blood of TOPD patients.

Conclusion

Tuberculosis infection can effectively induce autoimmune responses, contributing to increased expression of Th1 cells and associated cytokines, ultimately leading to immune dysregulation. Furthermore, the accumulation of pulmonary inflammatory response facilitates the progression of TOPD and is helpful for the clinical diagnosis and the development of targeted therapeutic drugs for this disease.

The role of lung-restricted autoantibodies in the development of primary and chronic graft dysfunction

Lung transplantation is a life-saving treatment for both chronic end-stage lung diseases and acute respiratory distress syndrome, including those caused by infectious agents like COVID-19. Despite its increasing utilization, outcomes post-lung transplantation are worse than other solid organ transplants. Primary graft dysfunction (PGD)-a condition affecting more than half of the recipients post-transplantation-is the chief risk factor for post-operative mortality, transplant-associated multi-organ dysfunction, and long-term graft loss due to chronic rejection. While donor-specific antibodies targeting allogenic human leukocyte antigens have been linked to transplant rejection, the role of recipient's pre-existing immunoglobulin G autoantibodies against lung-restricted self-antigens (LRA), like collagen type V and k-alpha1 tubulin, is less understood in the context of lung transplantation. Recent studies have found an increased risk of PGD development in lung transplant recipients with LRA. This review will synthesize past and ongoing research-utilizing both mouse models and human subjects-aimed at unraveling the mechanisms by which LRA heightens the risk of PGD. Furthermore, it will explore prospective approaches designed to mitigate the impact of LRA on lung transplant patients.

Effect of Different Doses of Propofol on Pulmonary Function and Inflammatory Response in Patients with Lung Ischemia Reperfusion Injury Induced by One-Lung Ventilation Based on Big Data Analysis

Objective

To analyze the effect of different doses of propofol on pulmonary function and inflammatory response in patients with lung ischemia reperfusion injury (LIRI) induced by one-lung ventilation (OLV) based on big data analysis.

Methods

A retrospective study was performed on 105 patients who underwent lobectomy in our hospital (January 2018 to January 2022). According to the doses of propofol, they were split into low-dose group (LDG), middle-dose group (MDG), and high-dose group (HDG), which received the continuous micropump infusion of propofol at the doses of 2 mg/(kg·h), 5 mg/(kg·h), and 10 mg/(kg·h) after induction, respectively, with 35 cases in each group. The indexes, such as the pulmonary function and inflammatory factors of patients, at different times were compared. The logistic regression analysis was performed according to the occurrence of LIRI.

Results

With no notable difference at T0 among the three groups (P > 0.05), the Cdyn levels significantly decreased at T1 (P < 0.05) and gradually increased at T2. The Cdyn levels at T1 and T2 were remarkably higher in HDG and MDG than in LDG (P < 0.05). With no notable differences at T0 and T1 among the three groups (P > 0.05), the P_A-aO₂ levels and RI values at T2 in MDG and HDG were lower compared with LDG (P < 0.05). The RI values at T1 and T2 in HDG were higher compared with MDG, with no obvious difference (P > 0.05). The OI levels at T1 and T2 in HDG were lower compared with the other two groups (P < 0.05), and the OI levels at T1, T2, and T3 in LDG were higher compared with MDG, with no obvious difference (P > 0.05). The TNF-α and ICAM-1 levels at T1 and T2 in MDG and HDG were lower compared with LDG, with no obvious difference between MDG and HDG (P > 0.05). Compared with LDG, the MDG and HDG at T1 and T2 had lower MDA levels (P < 0.05) and higher SOD levels (P < 0.05). Logistic regression analysis showed that Cdyn, P_A-aO₂, and OLV time were independent risk factors for LIRI in patients undergoing lobectomy.

Conclusion

Propofol has a good protective effect on lung function in patients with OLV-induced LIRI. Appropriately increasing the dose of propofol can effectively improve the local cerebral hypoxia and lung compliance of patients and reduce the inflammatory response and oxidative stress response, with 5 mg/(kg·h) as the clinical reference. Preoperative assessment and preparation should be made for patients, close attention should be paid to risk factors, such as Cdyn and P_A-aO₂, and OLV time should be controlled.

Update on the Features and Measurements of Experimental Acute Lung Injury in Animals: An Official American Thoracic Society Workshop Report

Advancements in methods, technology, and our understanding of the pathobiology of lung injury have created the need to update the definition of experimental acute lung injury (ALI). We queried 50 participants with expertise in ALI and acute respiratory distress syndrome using a Delphi method composed of a series of electronic surveys and a virtual workshop. We propose that ALI presents as a "multidimensional entity" characterized by four "domains" that reflect the key pathophysiologic features and underlying biology of human acute respiratory distress syndrome. These domains are 1) histological evidence of tissue injury, 2) alteration of the alveolar-capillary barrier, 3) presence of an inflammatory response, and 4) physiologic dysfunction. For each domain, we present "relevant measurements," defined as those proposed by at least 30% of respondents. We propose that experimental ALI encompasses a continuum of models ranging from those focusing on gaining specific mechanistic insights to those primarily concerned with preclinical testing of novel therapeutics or interventions. We suggest that mechanistic studies may justifiably focus on a single domain of lung injury, but models must document alterations of at least three of the four domains to qualify as "experimental ALI." Finally, we propose that a time criterion defining "acute" in ALI remains relevant, but the actual time may vary based on the specific model and the aspect of injury being modeled. The continuum concept of ALI increases the flexibility and applicability of the definition to multiple models while increasing the likelihood of translating preclinical findings to critically ill patients.

Pro-inflammatory IgG1 N-glycan signature correlates with primary graft dysfunction onset in COPD patients

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. The pathogenesis of COPD is complex; however, recent studies suggest autoimmune changes, characterized by the presence of autoantibodies to elastin and collagen, may contribute to disease status. COPD patients make up approximately 30% of all lung transplants (LTx) annually, however, little is known regarding the relationship between COPD-related autoantibodies and LTx outcomes. We hypothesized that COPD patients that undergo LTx and develop primary graft dysfunction (PGD) have altered circulating autoantibody levels and phenotypic changes as compared those COPD-LTx recipients that do not develop PGD. We measured total immunoglobulin and circulating elastin and collagen autoantibody levels in a cohort of COPD lung transplant recipients pre- and post-LTx. No significant differences were seen in total, elastin, or collagen IgM, IgG, IgG1, IgG2, IgG3, and IgG4 antibodies between PGD+ and PGD- recipients. Antibody function can be greatly altered by glycosylation changes to the antibody Fc region and recent studies have reported altered IgG glycosylation profiles in COPD patients. We therefore utilized a novel mass spectrometry-based multiplexed N-glycoprotein imaging approach and measured changes in IgG-specific antibody N-glycan structures. COPD-LTx recipients who developed PGD had significantly increased IgG1 N-glycan signatures as compared PGD- recipients. In conclusion, we show that immunoglobulin and autoreactive antibody levels are not significantly different in COPD LTx recipients that develop PGD. However, using a novel IgG glycomic analysis we were able to demonstrate multiple significant increases in IgG1 specific N-glycan signatures that were predictive of PGD development. Taken together, these data represent a potential novel method for identifying COPD patients at risk for PGD development and may provide clues to mechanisms by which antibody N-glycan signatures could contribute to antibody-mediated PGD pathogenesis.

Peptide-based immunotherapy against oxidized elastin ameliorates pathology in mouse model of smoke-induced ocular injury

PURPOSE

Age-related macular degeneration (AMD), the leading cause of blindness in western populations, is associated with an overactive complement system, and an increase in circulating antibodies against certain epitopes, including elastin. As loss of the elastin layer of Bruch's membrane (BrM) has been reported in aging and AMD, we previously showed that immunization with elastin peptide oxidatively modified by cigarette smoke (ox-elastin), exacerbated ocular pathology in the smoke-induced ocular pathology (SIOP) model. Here we asked whether ox-elastin peptide-based immunotherapy (PIT) ameliorates damage.

METHODS

C57BL/6J mice were injected with ox-elastin peptide at two doses via weekly subcutaneous administration, while exposed to cigarette smoke for 6 months. FcγR-/- and uninjected C57BL/6J mice served as controls. Retinal morphology was assessed by electron microscopy, and complement activation, antibody deposition and mechanisms of immunological tolerance were assessed by Western blotting and ELISA.

RESULTS

Elimination of Fcγ receptors, preventing antigen/antibody-dependent cytotoxicity, protected against SIOP. Mice receiving PIT with low dose ox-elastin (LD-PIT) exhibited reduced humoral immunity, reduced complement activation and IgG/IgM deposition in the RPE/choroid, and largely a preserved BrM. While there is no direct evidence of ox-elastin pathogenicity, LD-PIT reduced IFNγ and increased IL-4 within RPE/choroid. High dose PIT was not protective.

CONCLUSIONS

These data further support ox-elastin role in ocular damage in part via elastin-specific antibodies, and support the corollary that PIT with ox-elastin attenuates ocular pathology. Overall, damage is associated with complement activation, antibody-dependent cell-mediated cytotoxicity, and altered cytokine signature.

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.

Pre-existing self-reactive IgA antibodies associated with primary graft dysfunction after lung transplantation

BACKGROUND

Primary graft Dysfunction (PGD) results in significant mortality and morbidity after lung transplantation (LT). The objective of this study was to evaluate if pre-existing antibodies to self-antigens in sera of LT recipients are associated with PGD.

METHODS

The serum profiles of IgG and IgA autoantibodies were analyzed using a customized proteomic microarray bearing 124 autoantigens. Autoantibodies were analyzed using Mann-Whitney U test or Fisher exact test. The association of the autoantibodies with clinical phenotypes and survival was analyzed by Kaplan-Meier Survival Analysis. Receiver operating curve characteristics (ROC) were calculated to evaluate the predictive value of the autoantibodies for PGD.

RESULTS

51 patients were included in this study. Autoantigen microarray analysis on the pre-transplantation samples identified 17 IgA and 3 IgG autoantibodies which were significantly higher in recipients who developed PGD compared to those who did not (adjusted p < .05 and fold change>1.5). 6 IgA Abs were significantly associated with survival. Taken as a panel, an elevation of 6 IgA Abs had significant predictive value for PGD. Area under the curve value for the panel was 0.9413 for PGD with ROC analysis. Notably, 6 of the 17 IgA autoantigen targets are belong to proteoglycan family of extracellular matrix proteins.

CONCLUSION

Pre-existing IgG and IgA autoantibodies in LT patients correlate with PGD and with survival in a single center, small cohort of lung transplant recipients. Further validation is needed to confirm the findings in the study.

Early Identification of Chronic Lung Allograft Dysfunction: The Need of Biomarkers

A growing number of patients with end-stage lung disease have benefited from lung transplantation (LT). Improvements in organ procurement, surgical techniques and intensive care management have greatly increased short-term graft survival. However, long-term outcomes remain limited, mainly due to the onset of chronic lung allograft dysfunction (CLAD), whose diagnosis is based on permanent loss of lung function after the development of irreversible lung lesions. CLAD is associated with high mortality and morbidity, and its exact physiopathology is still only partially understood. Many researchers and clinicians have searched for CLAD biomarkers to improve diagnosis, to refine the phenotypes associated with differential prognosis and to identify early biological processes that lead to CLAD to enable an early intervention that could modify the inevitable degradation of respiratory function. Donor-specific antibodies are currently the only biomarkers used in routine clinical practice, and their significance for accurately predicting CLAD is still debated. We describe here significant studies that have highlighted potential candidates for reliable and non-invasive biomarkers of CLAD in the fields of imaging and functional monitoring, humoral immunity, cell-mediated immunity, allograft injury, airway remodeling and gene expression. Such biomarkers would improve CLAD prediction and allow differential LT management regarding CLAD risk.

Noteworthy Literature Published in 2018 for Thoracic Organ Transplantation

Publications of note from 2018 are reviewed for the cardiothoracic transplant anesthesiologist. Strategies to expand the availability of donor organs were highlighted, including improved donor management, accumulating experience with increased-risk donors, ex vivo perfusion techniques, and donation after cardiac death. A number of reports examined posttransplant outcomes, including outcomes other than mortality, with new data-driven risk models. Use of extracorporeal support in cardiothoracic transplantation was a prominent theme. Major changes in adult heart allocation criteria were implemented, aiming to improve objectivity and transparency in the listing process. Frailty and prehabilitation emerged as targets of comprehensive perioperative risk mitigation programs.

Prevalence of antibodies to lung self-antigens (Kα1 tubulin and collagen V) and donor specific antibodies to HLA in lung transplant recipients and implications for lung transplant outcomes: Single center experience

PURPOSE

For patients with end stage lung disease, lung transplantation (LT) remains the only definitive treatment option. Long term survival post LT is limited by acute and chronic allograft dysfunction. Antibodies to lung self-antigens Kα1Tubulin and collagen V (autoantibodies) have been implicated in adverse outcomes post LT. The aim of our study was to determine the prevalence of autoantibodies in pre- and post-transplant sera, evaluate the impact on post-transplant outcomes.

METHODS

In a prospective observational cohort analysis, 44 patients were enrolled who received LT between 09/01/2014 and 10/31/2015. Pre- and post-transplant sera were analyzed using enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies to collagen I, collagen V, and K-alpha 1 tubulin. The outcome variables are presence of primary graft dysfunction (PGD), cumulative acute cellular rejection (ACR), treatment with pulse steroids for clinical rejection, association with DSA, and onset of Bronchiolitis Obliterans Syndrome (BOS).

RESULTS

In our cohort, 33 patients (75%) tested positive for the presence of autoantibodies. Pre-transplant autoantibodies were present in 23 patients (70%). Only a small percentage (26%) cleared these antibodies with standard immunosuppression. Some developed de novo post-transplant (n = 10). PGD was observed in 34% of our cohort, however the presence of autoantibodies did not correlate with increase in the incidence or severity of PGD. The prevalence of donor specific antibodies (DSA) in the entire cohort was 73%, with an increased prevalence of DSA noted in the autoantibody positive group (78.7% vs. 54.5%) than in the autoantibody negative group. BOS was observed in 20% of the cohort, with a median time to onset of 291 days' post-transplant. Patients with pre-transplant autoantibodies had a statistically significant decrease in BOS-free survival (p = 0.029 by log-rank test).

CONCLUSIONS

In our cohort, we observed a high prevalence of autoantibodies and DSA in lung transplant recipients. Pre-transplant autoantibodies were associated with de novo development of DSA along with a decrease in BOS-free survival. Limitations to our study include the small sample size and single center enrollment, along with limited time for follow-up.