Konrad Hoetzenecker’s research while affiliated with Medical University of Vienna and other places

Rationale: While rodent lung fibrosis models are routinely used to evaluate novel antifibrotics, these models have largely failed to predict clinical efficacy of novel drug candidates for Idiopathic Pulmonary Fibrosis (IPF). Moreover, single target therapeutic strategies for IPF have failed and current multi-target standard of care drugs are not curative. Caveolin-1 (CAV-1) is an integral membrane protein, which, via its caveolin scaffolding domain (CSD), interacts with caveolin binding domains (CBD). CAV-1 regulates homeostasis, and its expression is decreased in IPF lungs. LTI-03 is a seven amino acid peptide derived from the CSD and formulated for dry powder inhalation; it was well tolerated in normal volunteers ( NCT04233814 ) and a safety trial is underway in IPF patients ( NCT05954988 ). Objectives: Anti-fibrotic efficacy of LTI-03 and other CSD peptides has been observed in IPF lung monocultures, and rodent pulmonary, dermal, and heart fibrosis models. This study aimed to characterize progressive fibrotic activity in IPF PCLS explants and to evaluate the antifibrotic effects of LTI-03 and nintedanib in this model. Methods: First, CBD regions were identified in IPF signaling proteins using in silico analysis. Then, IPF PCLS (n=8) were characterized by COL1A1 immunostaining, multiplex immunoassays, and bulk RNA sequencing following treatment every 12hrs with LTI-03 at 0.5, 3.0, or 10 μM; nintedanib at 0.1 μM or 1 μM; or control peptide (CP) at 10 μM. Measurements and Main Results: CBDs were present in proteins implicated in IPF, including VEGFR, FGFR and PDGFR. Increased expression of profibrotic mediators indicated active fibrotic activity in IPF PCLS over five days. LTI-03 dose dependently decreased COL1A1 staining, and like nintedanib, decreased profibrotic proteins and transcripts. Unlike nintedanib, LTI-03 did not induce cellular necrosis signals. Conclusion: IPF PCLS explants demonstrate molecular activity indicative of fibrosis during 5 days in culture and LTI-03 broadly attenuated pro-fibrotic proteins and pathways, further supporting the potential therapeutic effectiveness of LTI-03 for IPF.

Rationale: Passenger lymphocyte syndrome (PLS) may complicate minor ABO mismatched lung transplantation (LuTX) via donor-derived red cell antibody-induced hemolysis. Objectives: To ascertain the incidence and specificity of PLS-relevant antibodies amongst the study population as well as the dynamics of hemolysis parameters and the transfusion requirement of patients with or without PLS were the main objectives of this study. Methods: In this cohort study, 1011 patients who received LuTX between January 2010 and June 2019 were studied retrospectively. Prospectively, 87 LuTX (July 2019 to June 2021) were analyzed. Post-operative ABO antibody and hemolytic marker determinations, transfusion requirement, and duration of post-operative hospital care were analyzed. Retrospectively, blood group A recipients of O grafts with PLS were compared to those without. Measurements and main results: PLS affected 18.18% (retrospective) and 30.77% (prospective) of A recipients receiving O grafts, 5.13% of B recipients of O grafts, and 20% of AB patients receiving O transplants. Anti-A and anti-A1 were the predominant PLS-inducing antibodies, followed by anti-B and anti-A,B. Significantly lower hemoglobin values (median 7.4 versus 8.3 g/dL; p=0.0063) and an approximately twice as high percentage of patients requiring blood transfusions were seen in PLS. No significant differences in other laboratory markers, duration of hospital stay or other complications after LuTX were registered. Conclusions: Minor ABO incompatible LuTX recipients are at considerable risk of developing clinically significant PLS. Post-transplant monitoring combining red cell serology and hemolysis marker determination appears advisable not to overlook hemolytic episodes which necessitate antigen-negative transfusion therapy.

Background: Higher levels of inflammatory biomarkers are associated with an increased risk of perioperative atrial fibrillation and myocardial injury after non-cardiac surgery (MINS). Colchicine is an anti-inflammatory drug that might reduce the incidence of these complications. Methods: COP-AF was a randomised trial conducted at 45 sites in 11 countries. Patients aged 55 years or older and undergoing major non-cardiac thoracic surgery were randomly assigned (1:1) to receive oral colchicine 0·5 mg twice daily or matching placebo, starting within 4 h before surgery and continuing for 10 days. Randomisation was done with use of a computerised, web-based system, and was stratified by centre. Health-care providers, patients, data collectors, and adjudicators were masked to treatment assignment. The coprimary outcomes were clinically important perioperative atrial fibrillation and MINS during 14 days of follow-up. The main safety outcomes were a composite of sepsis or infection, and non-infectious diarrhoea. The intention-to-treat principle was used for all analyses. This trial is registered with ClinicalTrials.gov, NCT03310125. Findings: Between Feb 14, 2018, and June 27, 2023, we enrolled 3209 patients (mean age 68 years [SD 7], 1656 [51·6%] male). Clinically important atrial fibrillation occurred in 103 (6·4%) of 1608 patients assigned to colchicine, and 120 (7·5%) of 1601 patients assigned to placebo (hazard ratio [HR] 0·85, 95% CI 0·65 to 1·10; absolute risk reduction [ARR] 1·1%, 95% CI -0·7 to 2·8; p=0·22). MINS occurred in 295 (18·3%) patients assigned to colchicine and 325 (20·3%) patients assigned to placebo (HR 0·89, 0·76 to 1·05; ARR 2·0%, -0·8 to 4·7; p=0·16). The composite outcome of sepsis or infection occurred in 103 (6·4%) patients in the colchicine group and 83 (5·2%) patients in the placebo group (HR 1·24, 0·93-1·66). Non-infectious diarrhoea was more common in the colchicine group (134 [8·3%] events) than the placebo group (38 [2·4%]; HR 3·64, 2·54-5·22). Interpretation: In patients undergoing major non-cardiac thoracic surgery, administration of colchicine did not significantly reduce the incidence of clinically important atrial fibrillation or MINS but increased the risk of mostly benign non-infectious diarrhoea. Funding: Canadian Institutes of Health Research, Accelerating Clinical Trials Consortium, Innovation Fund of the Alternative Funding Plan for the Academic Health Sciences Centres of Ontario, Population Health Research Institute, Hamilton Health Sciences, Division of Cardiology at McMaster University, Canada; Hanela Foundation, Switzerland; and General Research Fund, Research Grants Council, Hong Kong.

Lung transplantation is the ultimate treatment for end-stage lung disease (ESLD) arising from various etiologies. This manuscript will focus on selected aspects of a theoretical perioperative lung transplantation plan, highlighting data-driven and theoretical techniques the authors would employ if they were the index patient undergoing surgery. Beginning with looking for a transplant center using an Internet search, patient advocacy organizations, and artificial intelligence guidance, the authors lay out a course for multidisciplinary care throughout the entire patient journey, ending with ideal approaches to recovery 6 months posttransplantation. Although the index case will focus on a theoretical patient with pulmonary fibrosis, the general management principles will be applicable across the entire spectrum of patients with ESLD presenting for lung transplantation.

Background Mast cells and basophils are effector cells of allergic reactions and display a number of activation-linked cell surface antigens. Of these antigens, however, only a few are functionally relevant and specifically expressed in these cells. Objective To identify mast cell- and basophil-specific surface molecules and to study their cellular distribution and regulation during cytokine-induced and IgE-dependent activation. Methods Multi-color flow cytometry was performed to recognize surface antigens and to determine changes in antigen expression upon activation. Results We identified Siglec-6 (CD327) as a differentially regulated surface antigen on human mast cells and basophils. In the bone marrow, Siglec-6 was expressed abundantly on mast cells in patients with mastocytosis and in reactive states, but was not detected on other myeloid cells, with the exception of basophils and monocytes. In healthy individuals, allergic patients, and patients with chronic myeloid leukemia (CML), Siglec-6 was identified on CD203c⁺ blood basophils, a subset of CD19⁺ B lymphocytes and few CD14⁺ monocytes, but not on other blood leukocytes. CML basophils expressed higher levels of Siglec-6 than normal basophils. Interleukin-3 (IL-3) promoted Siglec-6 expression on normal and CML basophils, and stem cell factor (SCF) increased the expression of Siglec-6 on tissue mast cells. Unexpectedly, IgE-dependent activation resulted in downregulation of Siglec-6 in IL-3-primed basophils whereas in mast cells, IgE-dependent activation augmented SCF-induced upregulation of Siglec-6. Conclusions Siglec-6 is a dynamically regulated marker of mast cells and basophils. Activated mast cells and basophils exhibit unique ´Siglec-6-responses´, including cytokine-dependent upregulation and unique differential, cell-specific responses to IgE-receptor cross-linking.

Background: Exaggerated fibroblast proliferation is a well-known feature in idiopathic pulmonary fibrosis (IPF) which may be - in part - due to insufficient autophagy, a lysosome dependent cellular surveillance pathway. Bcl2-associated athanogene 3 (BAG3) is a pivotal co-chaperone of the autophagy pathway. Here, we studied whether therapeutic modulation of BAG3-mediated autophagy can rescue insufficient autophagy and impact IPF fibroblast proliferation. Methods: Primary interstitial fibroblasts or precision cut lung slices (PCLS) of IPF lungs were treated with (1) the antifibrotic drug pirfenidone (Pirf), (2) the demethylating agent 5-azacytidine (Aza), (3) the BAG3 modulator cantharidin (Ctd). Autophagy flux was measured following pretreatment with the autophagy inhibitors or by GFP-RFP-LC3B transfection followed by drug treatments. Proliferation was measured by 5-bromo-2'-deoxyuridine assay. BAG3, filamin C (FLNC), proliferating-cell-nuclear-antigen (PCNA), collagen1A1 (COL1A1) and autophagy proteins were assessed by immunoblotting or immunofluorescence. Loss of function experiments were performed by siRNA mediated knockdown of BAG3. Results: In comparison with healthy donors, increased BAG3 protein was observed in IPF lung homogenates and IPF fibroblasts. In addition, the substrate of BAG3-mediated autophagy, FLNC, was increased in IPF fibroblasts, implying insufficient activation of BAG3-dependent autophagy. Therapeutic modulation of this pathway using Aza and Ctd alone or in combination with the IPF therapy drug Pirf rescued the insufficient BAG3-mediated autophagy and decreased fibroblast proliferation. Such effects were observed upon therapeutic modulation of BAG3 but not upon knock down of BAG3 per se in IPF fibroblasts. Similarly, PCLS of IPF patients showed a significant decrease in collagen deposition in response to these drugs, either alone or in a more potent form in combination with Pirf. Conclusions: Our study reveals that repurposing drugs that modulate autophagy regulating proteins render therapeutic benefits in IPF. Fine tuning of this pathway may hence signify a promising therapeutic strategy to ameliorate antifibrotic properties and augment the efficacy of current IPF therapy.

PURPOSE Dual-lumen extracorporal membrane oxygenation (ECMO) cannulation is considered technically challenging and harbors the risk for potential life-threatening complications during cannulation. Dual-lumen cannula insertion is either performed under ultrasound or fluoroscopy guidance. Both techniques have significant disadvantages, such as examiner-dependence or the necessity for transportation of the patient from the intensive care unit (ICU) to the operating room. DESCRIPTION Digital, mobile X-ray devices provide a novel, examiner-independent imaging modality for bedside dual-lumen ECMO cannulation. EVALUATION From 11/2019 to 11/2021, 23 dual-lumen cannulations were performed in 20 patients at the Department of Thoracic Surgery, Medical University of Vienna. 12/23 (52.2%) were inserted in the ICU using a mobile X-ray device. The remaining patients (47.8%) were cannulated in the operating room with conventional fluoroscopy guidance. In none of the procedures cardiovascular injuries occurred. Insertion site bleeding was the most common ECMO-related complication (n=2). CONCLUSIONS Dual-lumen cannulation using sequential X-rays can be performed safely. Especially in infectious patients or patients who require an awake ECMO, this technique overcomes disadvantages of established imaging modalities.

The tissue distribution and prognostic relevance of subtype‐specific proteins (ASCL1, NEUROD1, POU2F3, YAP1) present an evolving area of research in small cell lung cancer (SCLC). The expression of subtype‐specific transcription factors and P53 and RB1 proteins were measured by immunohistochemistry (IHC) in 386 surgically resected SCLC samples. Correlations between subtype‐specific proteins and in vitro efficacy of various therapeutic agents were investigated by proteomics and cell viability assays in 26 human SCLC cell lines. Besides SCLC‐A (ASCL1‐dominant), SCLC‐AN (combined ASCL1/NEUROD1), SCLC‐N (NEUROD1‐dominant) and SCLC‐P (POU2F3‐dominant), IHC and cluster analyses identified a quadruple‐negative SCLC subtype (SCLC‐QN). No unique YAP1‐subtype was found. The highest overall survival rates were associated with non‐neuroendocrine subtypes (SCLC‐P and SCLC‐QN) and the lowest with neuroendocrine subtypes (SCLC‐A, SCLC‐N, SCLC‐AN). In univariate analyses, high ASCL1 expression was associated with poor prognosis and high POU2F3 expression with good prognosis. Notably, high ASCL1 expression influenced survival outcomes independently of other variables in a multivariate model. High POU2F3 and YAP1 protein abundances correlated with sensitivity and resistance to standard‐of‐care chemotherapeutics, respectively. Specific correlation patterns were also found between the efficacy of targeted agents and subtype‐specific protein abundances. In conclusion, we have investigated the clinicopathological relevance of SCLC molecular subtypes in a large cohort of surgically resected specimens. Differential IHC expression of ASCL1, NEUROD1 and POU2F3 defines SCLC subtypes. No YAP1‐subtype can be distinguished by IHC. High POU2F3 expression is associated with improved survival in a univariate analysis, whereas elevated ASCL1 expression is an independent negative prognosticator. Proteomic and cell viability assays of human SCLC cell lines reveal distinct vulnerability profiles defined by transcription regulators. This article is protected by copyright. All rights reserved.

Endoplasmic reticulum (ER) and mitochondria (mito) play a vital role in alveolar type II cell (AEC2) homeostasis and are both stressed in patients with idiopathic pulmonary fibrosis (IPF). Up to now, no data are available with regard to ER–mito cross talk and tethering under conditions of IPF. We here demonstrate that ER–mitochondrial tethering is reduced upon experimental ER stress in vitro and in the IPF AECII ex vivo, and this is—at least in part—due to decreased phosphofurin acidic cluster sorting protein 2 (PACS-2, also called PACS2) protein levels. PACS2 levels are influenced by its interaction with the transient receptor potential cation channel subfamily V member 1 (TRPV1) and can be experimentally modified by the TRPV1-modulating drug capsaicin (CPS). Employing alveolar epithelial cells with overexpression of the terminal ER stress signaling factor Chop or the IPF-associated surfactant protein C mutation (SPC Δexon4 ) in vitro, we observed a restoration of PACS2 levels upon treatment with CPS. Similarly, treatment of precision cut lung slices from IPF patients with CPS ex vivo forwarded similar effects. Importantly, in all models such kind of intervention also greatly reduced the extent of alveolar epithelial apoptosis. We therefore conclude that therapeutic targeting of the PACS2–TRPV1 axis represents an interesting novel, epithelial-protective approach in IPF.