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Aims: The association of human herpesvirus 6 (HHV-6) species with pancreatic cancer is controversially discussed. The aim of this study was to further investigate the postulated association and to identify the basis of HHV-6 DNA positivity reported for pancreatic cancer tissue. Methods: All samples of patients with pancreatic cancer (cancer and surrounding tissue) were analyzed for presence of HHV-6 DNA by PCR and then selected cases by immunohistochemistry. Results: Sixty eight per cent (68% = 52/77) of all patients were HHV-6 DNA positive in any of the samples, 49% (38/77) were positive in tumor tissue. Specimens of just one patient were HHV-6A DNA positive, all other patients were positive for HHV-6B. Immunohistochemical analysis of HHV-6 DNA positive samples did not reveal any specific HHV-6B protein positive tumor cell. In contrast, supposed immune cells presented intra- and peritumorally expressed HHV-6B-protein. The cause of presence of these cells in the tumor stroma is unknown, as of yet. Conclusions: HHV-6 DNA-positivity of pancreatic cancer tissue described by us and others is probably not due to the infection of pancreatic cells by HHV-6, but rather due to the migration of HHV-6 positive immune cells into the pancreas. Based on our data, we suppose that there is no direct evidence for HHV-6 as a causative agent of pancreatic cancer, but further in-depth studies (including investigation of immune status of patients) are necessary to make definitive conclusions. [ABSTRACT FROM AUTHOR]

Ex situ lung perfusion (ESLP) is used for organ reconditioning, repair, and re-evaluation prior to transplantation. Since valid preclinical animal models are required for translationally relevant studies, we developed a 17 mL low-volume ESLP for double- and single-lung application that enables cost-effective optimal compliance “reduction” of the 3R principles of animal research. In single-lung mode, ten Fischer344 and Lewis rat lungs were subjected to ESLP and static cold storage using STEEN or PerfadexPlus. Key perfusion parameters, thermal lung imaging, blood gas analysis (BGA), colloid oncotic pressure (COP), lung weight gain, histological work-up, and cytokine analysis were performed. Significant differences between perfusion solutions but not between the rat strains were detected. Most relevant perfusion parameters confirmed valid ESLP with homogeneous lung perfusion, evidenced by uniform lung surface temperature. BGA showed temperature-dependent metabolic activities with differences depending on perfusion solution composition. COP is not decisive for pulmonary oedema and associated weight gain, but possibly rather observed chemokine profile and dextran sensitivity of rats. Histological examination confirmed intact lung architecture without infarcts or hemorrhages due to optimal organ procurement and single-lung application protocol using our in-house-designed ESLP system. [ABSTRACT FROM AUTHOR]

This article discusses the establishment of an ex vivo lung perfusion (EVLP) system for use in small animal models. EVLP is a technique that can expand the donor pool for lung transplantation and improve outcomes. The study used rat lungs and applied a protective mode with mechanical ventilation and controlled perfusion. The results showed stable values for respiration and hemodynamics, indicating sufficient perfusion and gas exchange capacity. The study concluded that the rat EVLP system is a stable and reproducible platform for further research in surgical, regenerative, immunomodulatory, tumor, and infection therapy. [Extracted from the article]

Objective: Recent studies demonstrated an integration of recipient derived cells into solid allografts, leading to intragraft microchimerism. Whether or to which extent this finding is influencing function and survival of the allograft has still to be elucidated. Methods: To detect epithelial chimerism in renal transplants from 36 patients tubular cells were harvested from paraffin embedded sequential allograft biopsies (n = 72) by laser-microdissection. To prevent contamination by recipient lymphocytes a preceding immunohistochemical stain for CD45 was done. DNA was isolated following standard protocols and PCR assay was performed for analysis of highly polymorphic short tandem repeat marker (SE33, heterozygosity 9%). In transplants with sex-mismatch (female donor to male recipient) chimerism was detected by in situ hybridization for the Y-chromosome, too. Findings were correlated to morphological diagnosis and clinical course. Additionally we investigated six neoplasms arising in renal allografts for their derivation. Results: Epithelial chimerism was detectable as early as 8 days after transplantation and lasted for nearly 8 years in our cohort. 88% (32/36) of our patients showed an epithelial chimerism. 26 of 36 (72%) patients had a stable chimerism in sequential biopsies (time between biopsies: 3-96 months; mean 16.6 months). 4 patients had no epithelial chimerism in two sequential biopsies. 3 patients showed a late onset of chimerism. In one patient a loss of chimerical epithelial cells was found. 4 pre-implant biopsies showed no chimerism. Y-chromosome in situ-hybridization (n = 8) revealed low percentages of chimeric tubular epithelial cells (2.4-6.6%). No correlation to morphological findings in allograft biopsies was detected. No correlation was found to outcome of graft function. Neoplasms arising in renal allografts are mostly donor derived. Conclusions: Epithelial microchimerism is an early and persistent phenomenon after renal transplantation. There is no correlation to morphological or functional outcome. Obviously recipient derived cells contribute in a minor fashion to tissue homeostasis, and cell turn over in renal allografts is predominantly enabled by donor cell renewal. [ABSTRACT FROM AUTHOR]

Herein we report the case of a young man, admitted to the Department of Cardiology and Angiology at Hannover medical school with shortness of breath and elevated Troponin. Few weeks earlier the patient received the first dose of BioNTech´s mRNA-vaccine (Comirnaty, BNT162b2). After diagnostic work-up revealed giant cell myocarditis, the patient received immunosuppressive therapy. In the present context of myocarditis after mRNA-vaccination we discuss this rare aetiology and the patient's treatment strategy in the light of current recommendations. [ABSTRACT FROM AUTHOR]

Background: Mouse orthotopic lung transplantation (MOLTx) models are extremely useful. However, there are only few studies on non-invasive monitoring methods for lung rejection in these models. Additionally, a model of chronic rejection has so far been difficult to reproduce consistently with MOLTx. Objective: To determine if CT scan of the lung graft can be considered a useful noninvasive monitoring method of evaluation of graft rejection in an animal lung transplantation model. Methods: Left MOLTx was performed from B10 donors into B6 recipients (from B6 donors for syngeneic controls). Following transplantation, 3 different doses of cyclosporine--5, 15, and 25 mg/kg daily--were administered in the first week to suppress acute rejection. Positive controls did not receive cyclosporine. 8 weeks after transplantation, CT and histological rejection grading were performed. Results: The negative controls did not show any inflammation. Positive controls revealed moderate acute rejection (A3). A3 was also detected in the 5-mg/kg group (100%). The 15-mg/kg group (n=7) demonstrated A3 in 4 mice and mild acute rejection (A2) in the remaining 3 mice. In this group, 4 mice had bronchiolitis obliterans (BO; C1, 57%). The 25-mg/kg group (n=3) showed A3 changes in 1 and A2 in 2 mice. On CT scan, lungs without BO (C0) had radiodensities of -278.1±110.7 Hounsfield units (HU). C1 lungs had ground-glass opacity or atelectasis with -83.4±46.8 HU (C0 vs. C1, p<0.001). On grouping with A2 or A3 in C0, significant differences were detected: -375.3±41.2 vs. -185.0±38.4 HU (A2+C0 vs. A3+C0, respectively), p=0.01. Conclusion: BO can be modeled using this MOLTx model by administration of subtherapeutic doses of cyclosporine. CT scans are a valid tool for monitoring of rejection following MOLTx. [ABSTRACT FROM AUTHOR]

Abstract Purpose Everolimus is a proliferation signal inhibitor used for triple immunosuppressive therapy following solid organ transplantation. Its positive benefits, such as reduction of acute rejection episodes and reduced nephrotoxicity have been shown in kidney- as well as heart transplantation. However the role of everolimus is less well defined in lung transplantation. We thus wished to study the effect of primary immunosuppression with everolimus in a preclinical large animal lung transplantation model. Methods Left-sided single lung transplantation from MHC-mismatched donors was performed in 11 adult minipigs. Intravenous pharmacologic immunosuppression was maintained for 28 days with 1.5 mg/kg/d methylprednisolone, 1.0 mg/kg/d azathioprine and cyclosporine A (blood levels 300-500 ng/ml; CsA group; n = 5). A further group (CsA + Ev; n = 6) received methylprednisolone, CsA (200–300 ng/ml) and Everolimus (5–10 ng/ml). Immunosuppression was discontinued on postoperative day (POD) 28. Graft survival was monitored by sequential chest X-rays, bronchoscopies and transbronchial biopsy histology. Results All animals survived the 28 day course of immunosuppressive therapy and showed healthy grafts on POD 28. Median allograft survival in the CsA group was 55 ± 15 days. CsA + Ev grafts showed median survival of 49 ± 86 days (p = 0.37). Conclusion Whereas everolimus might be advantageous as maintenance immunosuppressive agent, this data does not support an important role for everolimus in the immunosuppressive induction phase following lung transplantation. [ABSTRACT FROM AUTHOR]

Background: Several c-MET targeting inhibitory molecules have already shown promising results in the treatment of patients with Non-small Cell Lung Cancer (NSCLC). Combination of EGFR- and c-MET-specific molecules may overcome EGFR tyrosine kinase inhibitor (TKI) resistance. The aim of this study was to allow for the identification of patients who might benefit from TKI treatments targeting MET and to narrow in on the diagnostic assessment of MET. Methods: 222 tumor tissues of patients with NSCLC were analyzed concerning c-MET expression and activation in terms of phosphorylation (Y1234/1235 and Y1349) using a microarray format employing immunohistochemistry (IHC). Furthermore, protein expression and MET activation was correlated with the amplification status by Fluorescence in Situ Hybridization (FISH). Results: Correlation was observed between phosphorylation of c-MET at Y1234/1235 and Y1349 (spearman correlation coefficient rs = 0.41; p < 0.0001). No significant correlation was shown between MET expression and phosphorylation (p > 0.05). c-MET gene amplification was detected in eight of 214 patients (3.7 %). No significant association was observed between c-MET amplification, c-MET protein expression and phosphorylation. Conclusion: Our data indicate, that neither expression of c-MET nor the gene amplification status might be the best way to select patients for MET targeting therapies, since no correlation with the activation status of MET was observed. We propose to take into account analyzing the phosphorylation status of MET by IHC to select patients for MET targeting therapies. Signaling of the receptor and the activation of downstream molecules might be more crucial for the benefit of therapeutics targeting MET receptor tyrosine kinases than expression levels alone. [ABSTRACT FROM AUTHOR]

STUDY QUESTION: IS the regionalization of epididymitis related to epididymal segmentation? SUMMARY ANSWER: We show for the first time that luminal ascent of bacteria is strictly gated by epididymal segment boundaries, involving ductal constriction adjacent to the infected area. WHAT IS KNOWN ALREADY: The epididymal duct is a continuous, unbranched tube, coiled into segments that are divided by connective tissue septa. Sonographic analysis indicates that swelling associated with epididymitis is predominant in the cauda region. Epididymal segmentation has never been investigated in the context of pathological alterations. STUDY DESIGN, SIZE, AND DURATION: We analyzed segment-specific changes in the epididymal duct in a mouse model and in men. In the mouse epididymitis model (3 days post-infection, injection of bacteria into the lumen of the vas deferens), two Escherichia coli strains were tested: a uropathogenic strain CFT073 (UPEC, n = 7) and a fecal non-pathogenic strain NPEC470 (NPEC, n = 5). Two control groups: phosphate-buffered saline, sham-treated animals (n = 4) and untreated mice (n = 8). In addition, segmentation was verified by ex vivo injection of dye into the interstitial spaces of untreated mouse epididymides. Histological findings were compared with specimens from epididymitis patients (n = 10, age range 14-78, median 60 years) who underwent surgical intervention; control: samples from patients without epididymitis (n = 16, age range 38-87, median 73 years). PARTICIPANTS/MATERIALS, SETTING, AND METHODS: We investigated the ascending infections by detailed histological analysis in correlation with local infection status in a mouse epididymitis model. As a proof of concept, rare patient material from two archives was analyzed: epididymides from patients who underwent surgical intervention for persisting epididymitis, and for control, histologically normal epididymides from men who underwent orchiectomy for therapy of prostatic carcinoma. MAIN RESULTS AND THE ROLE OF CHANCE: Luminal ascent of E. coliin mi ce was strictly gated byepididymal segment boundaries. In the mouse model, both strains of E. coli were detected exclusively in the distal cauda segment associated with damage of the epithelium and muscle layer. Ductal constriction occurred in the non-infected upstream segments of infected area, putatively blocking further luminal ascent of bacteria in UPEC-infected animals. Corresponding histological and morphological changes were found in epididymitis patients. The caput region was found to be unaffected in patients and the mouse model. LIMITATIONS, REASONS FOR CAUTION: Patient samples represented advanced cases of epididymitis that made surgical intervention necessary. WIDER IMPLICATIONS OF THE FINDINGS: Our data demonstrate the impact of epididymal segmentation, presumably a protective response mechanism against infectious invasion and bacterial ascent, during epididymitis and affirm the importance of rapid intervention. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by grants from the State of Hessen (LOEWE-MIBIE) and the DFG (KFO 181). The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: No clinical trial involved. [ABSTRACT FROM AUTHOR]

Background: Several c-MET targeting inhibitory molecules have already shown promising results in the treatment of patients with Non-small Cell Lung Cancer (NSCLC). Combination of EGFR- and c-MET-specific molecules may overcome EGFR tyrosine kinase inhibitor (TKI) resistance. The aim of this study was to allow for the identification of patients who might benefit from TKI treatments targeting MET and to narrow in on the diagnostic assessment of MET. Methods: 222 tumor tissues of patients with NSCLC were analyzed concerning c-MET expression and activation in terms of phosphorylation (Y1234/1235 and Y1349) using a microarray format employing immunohistochemistry (IHC). Furthermore, protein expression and MET activation was correlated with the amplification status by Fluorescence in Situ Hybridization (FISH). Results: Correlation was observed between phosphorylation of c-MET at Y1234/1235 and Y1349 (spearman correlation coefficient rs = 0.41; p < 0.0001). No significant correlation was shown between MET expression and phosphorylation (p > 0.05). c-MET gene amplification was detected in eight of 214 patients (3.7 %). No significant association was observed between c-MET amplification, c-MET protein expression and phosphorylation. Conclusion: Our data indicate, that neither expression of c-MET nor the gene amplification status might be the best way to select patients for MET targeting therapies, since no correlation with the activation status of MET was observed. We propose to take into account analyzing the phosphorylation status of MET by IHC to select patients for MET targeting therapies. Signaling of the receptor and the activation of downstream molecules might be more crucial for the benefit of therapeutics targeting MET receptor tyrosine kinases than expression levels alone. [ABSTRACT FROM AUTHOR]

Primary graft dysfunction (PGD) is one of the leading causes of early mortality following lung transplantation (LTx). Here we investigated the correlation between PGD early after lung transplantation and the subsequent development of transplant atherosclerosis (TA) in a humanized mouse model. The pericardio-phrenic artery obtained from human donor lungs was implanted into the aorta of NOD/Rag-/-/IL-2rγc-/- mice reconstituted with either naive or primed allogeneic peripheral blood mononuclear cells (PBMC), that were obtained from the respective lung recipient either before or 21 days after transplantation. Parallel to the previously described experimental groups, there was another group. Here, T regs were enriched and additionally injected with the PBMC. Exactly as mentioned before, on day 0 and day 21. PGD was defined according to the 2017 ISHLT Guidelines. Histological assessment after 28 days showed significantly more intimal hyperplasia of arteries in mice reconstituted with PBMC from patients with PGD (24 hours after transplantation; score 2 or 3) compared to patients without PGD (score 0 or 1). The attached figure shows the measured occlusion in the individual groups. Enriching of PBMC with CD4+CD25high regulatory T cells (Treg) subpopulation, suppressed the development of TA in both PGD groups. TA was similarly suppressed by enriching of naive or alloantigen-primed Treg. Mice transplanted with arteries from donors undergoing PGD score 2 or 3 developed higher serum concentrations IFN-γ (PGD: 1129,9 conc. Pg/ml vs noPGD: 577,24 conc. Pg/ml), a pro-inflammatory TH1 signature cytokine. We conclude that both donor tissue inflammation and recipient T cell responses contribute to PGD, eventually triggering rejection. This inflammatory response can be suppressed by early supplementation with Treg cells, which suggests a potential target for future early interventions in lung transplantation. [ABSTRACT FROM AUTHOR]

After lung transplantation (LuTx), a transient chimerism of donor cells can be observed in recipient blood due to the migration of lymphocytes from the transplanted lung into the periphery. We aimed to characterize the phenotype of donor T and NK cells and to investigate their potential origin from tissue-resident memory (TRM) T and NK cells. Lymphocyte dynamics in recipient blood were determined in n=97 LuTx patients directly (T0), 24 hours (T24) and 3 (wks) weeks after LuTx using flow cytometry. Donor T and NK cells were analyzed by HLA class I allele-specific mAb in n=44 LuTx recipients. T and NK cell markers were used to discriminate circulating from TMR subsets in blood, organ storage solutions (perfusates, n=97), explanted lung parenchyma (n=28) and donor trachea (n=17). Single cell mRNA sequencing of explant lung parenchyma was conducted (n=16). In peripheral blood of all recipients, donor-derived T and NK cells were detected at T0, T24 and 3 wks after LuTx, showed higher CD69 expression compared to recipient cells (p=0.01 to 0.04) and were mostly CCR7− memory cells. This phenotype was similar to T and NK cells in corresponding perfusates. In recipient parenchyma and donor trachea, most CD69+ T and NK cells showed coexpression of TRM markers (CD103, CD49a, PD-1) with significant enrichment in trachea (p<0.05). These other TRM markers were not found in circulating donor T and NK cells or in perfusates, arguing for different memory T and NK cell subsets. Sc-mRNA sequencing confirmed distinct TRM and TRM-like T cell subsets in lung parenchyma according to separate expression profiles. The presence of TRM T and NK cells did not have an impact on primary graft dysfunction (PGD) 24h after LuTx. Yet, patients with high frequencies of donor T cells showed a trend towards CLAD-free survival 2 years post LuTx, although no statistical significance was reached (p=0.15). Our results demonstrate that donor T and NK cells found in recipient blood immediately after LuTx are separate subsets from circulating as well as pulmonary TRM T and NK cells, since they express CD69 but lack expression of other classical TRM markers. Donor T cells may be clinically relevant for tolerance induction and long-term survival after transplantation due to their unique features. [ABSTRACT FROM AUTHOR]

Background In adults, human papillomaviruses (HPV), lichen sclerosus et atrophicus (LSA) and phimosis are considered to be major risk factors for penile cancer. In boys, a possible association between phimosis, LSA and HPV has been suggested. Objective To investigate the role of HPV in the persistence of phimosis in children. Patients and methods Out of a cohort of 420 boys presenting with foreskin problems, we prospectively sampled the preputial tissue of 82 patients during circumcision: 46 with steroid-naïve and 36 with steroid-resistant phimosis. All foreskins were assessed clinically and histopathologically with regard to appearance, inflammation, oedema, epithelial degeneration and fibrosis. The viral status of the foreskins was determined by immunohistochemistry and highly sensitive PCR, with subsequent subtyping by DNA hybridization (HPV types 6, 11, 16, 18, 31, 33, 35, 39, 42, 44, 45, 51-54, 56, 58, 59, 61, 62, 66-68, 70, 72, 73, 81-84, 90, 91). Results The foreskins appeared normal in 62 boys and suggestive of LSA in one single case. Small cracks or white scars were present in seven steroid-naïve and 12 steroid-resistant foreskins. LSA was diagnosed microscopically in two of the steroid-naïve and six of the steroid-pretreated group. No evidence of HPV was found in any of the juvenile foreskins. Conclusions Our prospective study has provided evidence that HPV is not usually present in the foreskin of boys with persistent phimosis after their first year of life and that topical glucocorticoid treatment failure is not associated with HPV or any specific histopathological changes. [ABSTRACT FROM AUTHOR]

OBJECTIVE: : Angiopoietin-2, an antagonistic ligand of the endothelial Tie2 receptor, has been identified as a gatekeeper of endothelial activation. We examined whether the release of Angiopoietin-2 correlates with surrogates of organ dysfunction and outcome in patients with acute liver failure. DESIGN: : Retrospective clinical and immunohistological study. SETTING: : Intensive care unit of a university hospital. PATIENTS: : Thirty-seven patients with acute liver failure and 20 healthy control subjects. INTERVENTIONS: : None. MEASUREMENTS AND MAIN RESULTS: : Angiopoietin-2 levels were measured in sera from 37 patients with acute liver failure on admission and from 20 healthy control subjects. Median age of patients with acute liver failure was 34 yrs, 29 were female, and 21 developed encephalopathy grade 3 or greater. Nine patients survived to day 28 without transplantation, five died without transplantation, and 23 received a transplant. Median (interquartile range) Angiopoietin-2 serum concentrations steadily increased across the following groups: healthy control subjects (1.4 [0.9-1.7] ng/mL), patients with transplant-free recovery (10.0 [4.7-12.1] ng/mL), and patients who reached the composite end point of death or emergency liver transplantation (16.8 [11.3-39.5] ng/mL). Angiopoietin-2 release correlated strongly with surrogate markers of organ dysfunction and disease severity measures (lactate, platelet count, Sequential Organ Failure Assessment score, and Simplified Acute Physiology Score III). Angiopoietin-2 levels were higher in patients with acute kidney injury and patients on mechanical ventilation. Furthermore, Angiopoietin-2 levels were closely associated with Bilirubin-Lactate-Etiology score but not with other liver-specific markers. Unadjusted and adjusted Cox's proportional hazards analyses identified Angiopoietin-2 as a predictor of the composite end point of death or transplantation. Finally, immunohistological studies showed that Angiopoietin-2 protein was upregulated in acute liver failure explants compared with matched liver biopsies obtained at baseline. CONCLUSIONS: : Collectively, our data show that circulating Angiopoietin-2, which potentially originates from the injured liver, correlates with several features of multiple organ dysfunction syndrome and independently predicts outcome. Tie2 agonists may have potential as an endothelium-targeted therapy to ameliorate multiple organ dysfunction syndrome and improve outcome in acute liver failure. [ABSTRACT FROM AUTHOR]

The thrombopoietin receptor gene (MPL) is expressed in megakaryocytes and exhibits the gain of function point mutation W515K/L in ∼5% of patients with primary myelofibrosis/idiopathic myelofibrosis (PMF) representing one subtype of the chronic myeloproliferative disorders (myeloproliferative neoplasm). A series of primary and secondary acute myeloid leukaemias (AML) with megakaryoblastic phenotype and myelofibrosis unrelated to PMF (n=12) was analysed for the MPLW515K/L mutation by pyrosequencing. In three cases (25%), MPLW515L was found and in two of these a combination with trisomy 21 or the Philadelphia chromosome occurred. None of the secondary AML cases evolving from pre-existing PMF showed MPLW515K/L (n=4). We conclude that MPLW515L occurs in a considerable proportion of acute megakaryoblastic leukaemias with myelofibrosis unrelated to PMF.Leukemia (2009) 23, 852–855; doi:10.1038/leu.2008.371; published online 5 February 2009 [ABSTRACT FROM AUTHOR]

Purpose In previous studies, we identified donor lymphocytes in peripheral blood of recipients directly after transplantation and persisting at least three weeks that were characterized by the tissue retention marker CD69. In order to determine their origin, we hypothesized that donor T and NK cells have a peculiar tissue-resident memory phenotype that is shared between cells derived from lung perfusates, trachea parenchyma and lymph nodes. Methods Donor lymphocytes in recipient blood were determined in 27 lung transplant patients at T0, T24, 3 weeks by staining of donor HLA class I molecules in combination with lineage- and tissue-specific markers using flow cytometry. The phenotype of T and NK cells in perfusates (n=30), donor trachea (n=5), and lymph node (n=10), recipient explanted parenchyma (n=15) was compared to circulating cells using the same markers. Results In peripheral blood of all lung transplant recipients, donor derived T and NK cells were detected at T0, T24 and 3 weeks and had higher CD69 expression compared to recipient cells (p=0.001 to 0.03) and were mostly CD25−. This phenotype was similar to T and NK cells in corresponding perfusates, with significantly increased CD69 expression compared to circulating PBMCs (all p<0.005) without CD25. Perfusate, trachea and donor NK cells, were CD56dim CD16+, in contrast to lung-draining lymph nodes that only possess CD56bright CD16− NK cells. T cells from trachea and lymph node showed also high CD69 expression and a significant enrichment of effector memory (CCR7− CD45RO+) T cells (all p<0.03). In donor trachea and recipient parenchyma, CD69+ T cells showed coexpression of other tissue residency markers such as CD103, CD49a and PD-1, while these were not found in perfusates, highlighting the differences between these compartments. Conclusion Our results suggest that donor T and NK cells found in the periphery of lung transplant recipients are derived from lung parenchyma and represent tissue-resident memory cells. This transient chimerism in recipient blood might be clinically relevant for tolerance induction after transplantation due to unique features of TRM T and NK cells. [ABSTRACT FROM AUTHOR]

After lung transplantation (LuTx), a transient chimerism of donor cells exists in the blood of recipients due to the migration of lymphocytes from the transplanted lung into the periphery. We aimed to characterize the phenotype of donor CD8+/CD4+ T and NK cells and to investigate whether they might represent tissue-resident memory (TRM) cells. Lymphocyte dynamics in recipient blood were determined in 97 LuTx patients directly (T0), 24h (T24) and 3 (wks) weeks after LuTx using flow cytometry with lineage-, tissue-, and donor HLA class I allele-specific mAb. The same makers were used to determine the phenotype of lymphocytes present in perfusate (n=102), recipient explanted lung parenchyma (n=28) and donor trachea (n=17). In peripheral blood of all recipients, donor-derived CD4+/CD8+ T and CD56dim NK cells were detected at T0, T24 and 3 wks after LuTx and had higher CD69 expression compared to recipient cells (p=0.01 to 0.04), were mostly CCR7− memory cells and CD25−. This phenotype was similar to T and NK cells in corresponding perfusates. In recipient parenchyma and donor trachea, most CD69+ T and NK cells showed coexpression of other tissue residency markers such as CD103, CD49a and PD-1 with significant enrichment in trachea (p<0.05). In contrast, these markers were not found in circulating donor lymphocytes and perfusates, indicating that they represent distinct memory T and NK subsets. Donor T and NK cells showed higher IFN-g production with and w/o PMA/Iono stimulation compared to recipient cells (p<0.05). The presence of these particular TRM cells did not have an impact on the development of PGD 24h after transplantation. However, patients with high frequencies of donor T cells showed a trend towards a CLAD-free survival 2 years post LuTx, although no statistical significance was reached (p=0.15). Our results demonstrate that donor T and NK cells found in the periphery of LuTx recipients are a distinct subset from circulating lymphocytes and TRM cells present in lung tissue, since they express CD69 but lack expression of other classical TRM markers. They display a higher functional capacity despite the onset of immunosuppression. Donor T cells might be clinically relevant for tolerance induction and long-term survival after transplantation due to their unique features. [ABSTRACT FROM AUTHOR]

After lung transplantation (LuTx), a transient chimerism of donor cells exists in the blood of recipients due to the migration of lymphocytes from the transplanted lung into the periphery. We aimed to characterize the phenotype of donor CD8+ and CD4+ T and NK cells and to investigate whether they might represent tissue-resident memory (TRM) cells. Lymphocyte dynamics in recipient blood were determined in 97 lung transplant patients directly (T0), 24 hours (T24) and 3 (wks) weeks after LuTx using flow cytometry with lineage-, tissue-, and donor HLA class I allele-specific mAb. The same makers were used to determine the phenotype of lymphocytes present in organ storage solution (perfusate, n=102), recipient explanted lung parenchyma (n=28) and donor trachea (n=17). In peripheral blood of all recipients, donor-derived CD4+ and CD8+ T and CD56dim NK cells were detected at T0, T24 and 3 wks after LuTx and had higher CD69 expression compared to recipient cells (p<0.05) and were mostly CD25− CCR7− memory cells. This phenotype was similar to T and NK cells in corresponding perfusates. In lung parenchyma and trachea, most CD69+ T and NK cells showed coexpression of other tissue residency markers such as CD103, CD49a and PD-1 with significant enrichment in trachea (p<0.05). These markers were not found in circulating donor lymphocytes and perfusates, indicating that they represent distinct memory T and NK subsets. Donor T and NK cells showed higher IFN-γ production with PMA/ionomycin stimulation compared to recipient cells (p<0.05). The presence of these particular TRM cells did not have an impact on the development of PGD 24h after LuTx. However, patients with high frequencies of donor T cells showed a trend towards a CLAD-free survival 2 years post LuTx, although no statistical significance was reached (p=0.15). Our results demonstrate that donor T and NK cells found in the blood of LuTx recipients are a distinct subset from circulating lymphocytes and TRM cells present in lung tissue, since they express CD69 but lack expression of other classical TRM markers. They display a higher functional capacity despite the onset of immunosuppression. Donor T cells might be clinically relevant for tolerance induction and long-term survival after transplantation due to their unique features. [ABSTRACT FROM AUTHOR]