Endothelial damage and dysfunction in acute graft-versus-host disease

Soluble Thrombomodulin Is Associated With Endothelial Dysfunction Syndromes After Pediatric Hematopoietic Stem Cell Transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is challenged by endothelial dysfunction-related syndromes like sinusoidal obstruction syndrome (SOS), capillary leak syndrome (CLS), and severe acute graft-versus-host disease (aGvHD). We investigated soluble thrombomodulin (sTM), an endothelial damage marker, in relation to endothelial dysfunction syndromes after pediatric HSCT.

PROCEDURE

We measured sTM levels in 113 children before conditioning until Day +180 after HSCT.

RESULTS

Plasma levels of sTM increased significantly after conditioning, particularly in patients receiving busulfan-based regimens (Day +7: 5.0 vs. 7.6 ng/mL, p = 0.0023), and remained elevated until Day +180 after HSCT. Children diagnosed with SOS (n = 51) had significantly higher sTM levels at Days +7 and +14 than children without SOS (Day +7: 7.3 vs. 5.0 ng/mL, p = 0.017). High sTM levels at Day +14 were associated with aGvHD Grade III-IV (n = 8) in multivariable analysis (OR = 3.0 per quartile increase in sTM, p = 0.021). Likewise, children diagnosed with CLS (n = 15) displayed higher sTM levels at Day +7 (5.3 vs. 8.0 ng/mL, p = 0.037), while sTM levels were not associated with engraftment syndrome or bacteremia.

CONCLUSION

High sTM levels early after pediatric HSCT are associated with the development of SOS, CLS, and severe aGvHD. These results suggest that conditioning-induced endothelial damage and activation of pro-thrombotic environment play key roles in the pathogenesis of these syndromes, indicating that sTM may prove clinically useful to guide early diagnosis and treatment of endothelial damage syndromes.

Leucine-rich α-2 glycoprotein 1 (LRG1) during inflammatory complications after allogeneic stem cell transplantation and CAR-T cell therapy

BACKGROUND

Previous data indicated that the leucine-rich α-2 glycoprotein 1 (LRG1) pathway contributes to vascular dysfunction during cancer growth. Therapeutic targeting of LRG1 normalized tumor vessel dysfunction and enhanced the efficacy of anti-cancer adoptive T cell therapy. A major clinical problem after allogeneic hematopoietic stem cell transplantation (alloHSCT) and after chimeric antigen receptor (CAR) T-cell therapy is the induction of hyperinflammatory side effects, which are typically associated with severe endothelial dysfunction.

METHODS

We investigated LRG1 in preclinical models and in patient samples.

RESULTS

In prospective studies, we found elevated LRG1 serum levels in patients with cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome after CAR-T-cell therapy as well as in patients with acute graft-versus-host disease (aGVHD) after alloHSCT.In preclinical models of aGVHD, we found vasculature-associated LRG1 upregulation as well as LRG1 pathway gene upregulation. The genetic deletion of LRG1 in alloHSCT donors and in alloHSCT recipients led to reduced clinical and histological aGVHD. In line with this, LRG1 deletion led to clinically and histologically reduced disease severity in experimental inflammatory models of colitis (dextran sulfate sodium colitis) and paw edema. LRG1 deletion reduced inflammation-related vascular leakiness, endothelial cell proliferation, and migration.

CONCLUSIONS

The current data support the hypothesis that LRG1 is an attractive therapeutic target after alloHSCT and after CAR-T cell therapy for cancer because of its role in dysfunctional tumor vessels as well as in inflammatory complications.

The EASIX score as a predictor of sinusoidal obstruction syndrome and nonrelapse mortality in paediatric patients receiving allogeneic haematopoietic stem cell transplantation

The endothelial activation and stress index (EASIX) score, calculated as [lactate dehydrogenase (LDH; U/L) × serum creatinine (mg/dL)]/platelets (10e9/L)], has been shown to be predictive of nonrelapse mortality (NRM) and endothelial complications in adults receiving allogeneic stem cell transplantation (allo-HSCT); however, definitive results are lacking for children. We retrospectively evaluated consecutive paediatric allo-HSCT recipients and calculated the log2 EASIX score every day from admission to day +35. In 167 allo-HSCT recipients, the EASIX score increased from before conditioning (-0.79) to a maximum score on day +20 (2.23). In multivariate analysis, the EASIX score at day +7 was an independent predictor of sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) (OR 1.52; 95% CI, 1.08-2.13; p = 0.017) and NRM (OR 1.68; 95% CI 1.16-2.42; p = 0.006). At several time points between day +0 and day +14, the EASIX score was independently associated with NRM, with the strongest predictive power being observed on day +12 (OR 3.05; 95% CI, 1.53-6.10; p = 0.002). Age correlated linearly with the EASIX score at all analysed time points, but score prediction was confirmed even when age was added to the multivariate model, indicating that age was not a confounding factor in the observed associations. The EASIX score determined shortly after transplantation can be further explored as a predictor of SOS/VOD and NRM in paediatric allo-HSCT recipients.

Non-invasive Estimation of Microvasculopathy & Endothelial Dysfunction in Stem Cell Transplant Recipients and its Relationship with GVHD

Introduction

Microvasculopathy and endothelial dysfunction play important roles in the development of post-transplant complications, including graft-versus-host disease (GVHD). We assessed structural microvasculopathy by employing nailfold video capillaroscopy (NFVC) and endothelial dysfunction via flow-mediated dilatation (FMD) of the brachial artery in recipients of hematopoietic stem cell transplantation.

Patients and methods

Recipients of stem cell transplantation were included in this study post day+100 and divided into two cohorts. The first cohort consisted of 35 recipients of allogeneic hematopoietic stem cell transplantation (HCT) and the second cohort was comprised of 31 recipients of autologous HCT. A third cohort included 35 healthy individuals. NFVC was conducted on the second to fifth fingers of both hands using an Optilia video capillaroscope at 200× magnification, and the images were analyzed according to the European Alliance of Associations for Rheumatology (EULAR) criteria. The following parameters were used to measure vasculopathy: (a) median capillary density, derived from the capillary density of eight fingers, (b) median capillary diameter, derived from maximum capillary apical diameters of eight fingers, and (c) significant neoangiogenesis (neoangiogenesis present in ≥2 fingers). FMD of the right brachial artery was observed by high-resolution ultrasonography using the principle of post-occlusive reactive hyperemia, and video images were analyzed using edge-detecting software.

Results

The median capillary diameter was significantly higher in the allo-HCT cohort (20.56±5.17 micrometer) compared to the auto-HCT cohort (16.19±3.31 micrometer; p<0.001) and healthy controls (14.66±2.61 micrometer; p<0.001). The median capillary density was significantly lower in the allo-HCT cohort (median: 6 capillaries/mm, range: 5-9 capillaries/mm) compared to the auto-HCT cohort (median: 8.5 capillaries, range: 5-12 capillaries/mm; p<0.001) and healthy controls (median: 8 capillaries/mm, range: 7-10.5 capillaries/mm; p<0.001). The allo-HCT cohort had a higher proportion of patients with significant neoangiogenesis (86%) than the auto-HCT cohort (10%) and healthy controls (9%). The presence of significant neoangiogenesis was more frequent in the subgroup of patients with a history of GVHD (93%) compared to the subgroup of patients without any history of GVHD (57%; p=0.044). No significant differences in NFVC parameters or FMD were observed between recipients of myeloablative and reduced-intensity conditioning regimens. There was no significant difference in NFVC parameters between the auto-HCT cohort and healthy controls. There was no significant difference in FMD among the three cohorts; however, a higher proportion of patients in the allo-HCT cohort (28%) had lower FMD than those in the auto-HCT cohort (3%) and healthy controls (6%), suggesting endothelial dysfunction.

Conclusions

Our findings demonstrate the presence of structural microvasculopathy in allo-HCT recipients and suggest a possible role of alloreactivity in the pathogenesis of post-HCT microvasculopathy.

A genome-wide association study on hematopoietic stem cell transplantation reveals novel genomic loci associated with transplant outcomes

Introduction

Data on genomic susceptibility for adverse outcomes after hematopoietic stem cell transplantation (HSCT) for recipients are scarce.

Methods

We performed a genome wide association study (GWAS) to identify genes associated with survival/mortality, relapse, and severe graft-versus-host disease (sGvHD), fitting proportional hazard and subdistributional models to data of n=1,392 recipients of European ancestry from three centres.

Results

The single nucleotide polymorphism (SNP) rs17154454, intronic to the neuronal growth guidant semaphorin 3C gene (SEMA3C), was genome-wide significantly associated with event-free survival (p=7.0x10-8) and sGvHD (p=7.5x10-8). Further associations were detected for SNPs in the Paxillin gene (PXN) with death without prior relapse or sGvHD, as well as for SNPs of the Plasmacytoma Variant Translocation 1 gene (PVT1, a long non-coding RNA gene), the Melanocortin 5 Receptor (MC5R) gene and the WW Domain Containing Oxidoreductase gene (WWOX), all associated with the occurrence of sGvHD. Functional considerations support the observed associations.

Discussion

Thus, new genes were identified, potentially influencing the outcome of HSCT.

Easix Score Correlates With Endothelial Dysfunction Biomarkers and Predicts Risk of Acute Graft-Versus-Host Disease After Allogeneic Transplantation

Plasma biomarkers of endothelial dysfunction have been postulated for the diagnosis and prognosis of acute graft-versus-host disease (aGVHD). However, their use is not validated in clinical practice yet. The endothelial activation and stress index (EASIX), a simple score based on routine laboratory parameters, is considered to be an indirect marker of endothelial damage. High value of EASIX was correlated with worse non-relapse mortality (NRM) and overall survival (OS) and a high risk of sinusoidal obstructive syndrome and transplant-associated thrombotic microangiopathy (TA-TMA). This study investigates the predictive value of plasma biomarkers and the EASIX score for the prediction of aGVHD. We assessed vascular cell adhesion molecule-1 (VCAM-1), tumor necrosis factor receptor 1 (TNFR1), and VWF:Ag plasma levels and the EASIX score before allogeneic hematopoietic stem cell transplantation (allo-HSCT) and on days 0, 3, 7, 14, and 21 in an experimental cohort (n = 33). EASIX was transformed to a base-2 logarithm to perform the analysis. For the most relevant biomarkers, we estimate the optimal cutoff values and the discriminatory ability to differentiate patients with high-risk of aGVHD. The conclusions obtained in the experimental cohort were validated in a large cohort of 321 patients at the same institution. Plasma biomarkers and EASIX showed similar post-transplantation dynamics consisting of a progressive increase. Multivariate analysis showed an association between high TNFR1 levels and Log-2 EASIX score on day 7 after transplantation with an increased likelihood of developing aGVHD (hazard ratio [HR] = 1, P = .002; HR = 2.31, P = .013, respectively). Patients with TNFR1 ≥1300 ng/mL (HR = 7.19, P = .006) and Log2-EASIX ≥3 (HR = 14.7, P <.001) at day 7 after transplantation were more likely to develop aGVHD with high predictive accuracy (C-index of 74% and 81%, respectively). In the validation cohort, patients with Log2-EASIX ≥3 on day 7 after transplantation presented a significantly higher incidence of grade II-IV aGVHD (HR = 1.94, P = .004) independent of GVHD prophylaxis (HR = 0.38, P = .004), conditioning regimen (HR = 0.59, P =.02) and type of donor (HR = 2.38, P = .014). Differential degree of endothelial damage can be measured using both EASIX score and plasma biomarkers in the early post-transplantation period. Patients at risk of developing aGVHD could be easily identified by a high EASIX score. Both indicators of endothelial activation represent a promising approach to predict aGVHD.

Endothelial Activation and Stress Index Score as a Prognostic Factor of Cytokine Release Syndrome in CAR-T Patients - A Retrospective Analysis of Multiple Myeloma and Large B-Cell Lymphoma Cohorts

Endothelial Activation and Stress Index (EASIX) has been proposed as a prognostic factor of adverse events or survival in hematological malignancies. Endothelial dysfunction has been associated with complications following stem cell transplantation and chimeric antigen receptor (CAR)-T therapy. This retrospective cohort study evaluated the utility of the EASIX score as a prognostic factor of cytokine release syndrome (CRS) in multiple myeloma/light-chain amyloidosis (MM/AL amyloidosis; N = 69) and large B-cell lymphoma (LBCL) cohorts (N = 65). Occurrence of CRS grade ≥3 was the primary endpoint. For both cohorts, the EASIX and simplified EASIX (s-EASIX) scores were calculated at four different time points before CAR-T infusion to assess its prognostic value. In the MM/AL amyloidosis cohort, neither EASIX nor s-EASIX scores calculated at any time point were associated with the occurrence of CRS grade ≥3. In the LBCL cohort, EASIX and s-EASIX scores measured before lymphodepletion (EASIX-pre and s-EASIX-pre) showed a significant relationship with CRS grade ≥3 (odds ratio [OR] = 1.06 and OR = 1.05, respectively). The cutoff value of 1.835 for EASIX-pre was associated with 4.59-fold increased OR of CRS grade ≥3 (95% confidence interval [CI]: 1.13-21.84), whereas s-EASIX-pre cutoff equaled 2.134 and was associated with 4.13-fold increased OR of CRS grade ≥3 (95% CI: 1.01-17.93). However, after internal validation with bootstrapping, the significance was lost both for the EASIX-pre and s-EASIX-pre cutoff. The presented findings indicate that the EASIX scores fail to predict CRS in MM/amyloidosis CAR-T patients, whereas they can be implemented as CRS grade ≥3 predictors in LBCL CAR-T patients.

Preconditioning Modified-Easix as a Predictor of Prognosis in Allogeneic Hematopoietic Stem Cell Transplant Recipients

Allogeneic hematopoietic stem cell transplantation (alloHCT) is associated with severe complications, most of which share a common physiopathological background characterized by endothelial dysfunction. A novel risk assessment model, endothelial activation and stress index (EASIX), has been introduced as a predictor of endothelial activation. This retrospective study was performed to evaluate the predictive impact of EASIX/modified-EASIX (mEASIX) on transplant outcome. Medical records of 398 alloHCT recipients [median age: 43(17-71) years; M/F: 243/155] were examined. EASIX/mEASIX were calculated at specific time points before and after transplantation. EASIX/mEASIX were significantly associated with transplant complications including engraftment syndrome, sinusoidal obstruction syndrome, febrile neutropenia and transplant associated thrombotic microangiopathy. The probability of overall survival was significantly higher in low-preconditioning mEASIX (day -7) group (37% vs 25.2%; p = 0.008; HR: 2.057; 95% CI: 1.208-3.504). The probabilities of day30 mortality (2.9% vs 19.4%; p = 0.017; HR: 7.028; 95% CI: 1.418-34.836), day100 mortality (9% vs 33%; p = 0.004; HR: 4.469; 95% CI: 1.619-12.336) and non relapse mortality (44.8% vs 61.4%; p = 0.005; HR: 2.551; 95% CI: 1.318-4.941) were lower in low-preconditioning mEASIX (day -7) group. This retrospective cohort analysis demonstrates the significant impact of EASIX/mEASIX on transplant complications and survival. Prospective analyses are mandatory to assess the predictive role of EASIX/mEASIX in clinical practice.

The novel role of lymphatic vessels in the pathogenesis of ocular diseases

Historically, the eye has been considered as an organ free of lymphatic vessels. In recent years, however, it became evident, that lymphatic vessels or lymphatic-like vessels contribute to several ocular pathologies at various peri- and intraocular locations. The aim of this review is to outline the pathogenetic role of ocular lymphatics, the respective molecular mechanisms and to discuss current and future therapeutic options based thereon. We will give an overview on the vascular anatomy of the healthy ocular surface and the molecular mechanisms contributing to corneal (lymph)angiogenic privilege. In addition, we present (i) current insights into the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea triggered e.g. by inflammation or trauma, (ii) the role of lymphatic vessels in different ocular surface pathologies such as dry eye disease, corneal graft rejection, ocular graft versus host disease, allergy, and pterygium, (iii) the involvement of lymphatic vessels in ocular tumors and metastasis, and (iv) the novel role of the lymphatic-like structure of Schlemm's canal in glaucoma. Identification of the underlying molecular mechanisms and of novel modulators of lymphangiogenesis will contribute to the development of new therapeutic targets for the treatment of ocular diseases associated with pathological lymphangiogenesis in the future. The preclinical data presented here outline novel therapeutic concepts for promoting transplant survival, inhibiting metastasis of ocular tumors, reducing inflammation of the ocular surface, and treating glaucoma. Initial data from clinical trials suggest first success of novel treatment strategies to promote transplant survival based on pretransplant corneal lymphangioregression.

Enforced gut homing of murine regulatory T cells reduces early graft-versus-host disease severity

Damage to the gastrointestinal tract following allogeneic hematopoietic stem cell transplantation is a significant contributor to the severity and perpetuation of graft-versus-host disease. In preclinical models and clinical trials, we showed that infusing high numbers of regulatory T cells reduces graft-versus-host disease incidence. Despite no change in in vitro suppressive function, transfer of ex vivo expanded regulatory T cells transduced to overexpress G protein-coupled receptor 15 or C-C motif chemokine receptor 9, specific homing receptors for colon or small intestine, respectively, lessened graft-versus-host disease severity in mice. Increased regulatory T cell frequency and retention within the gastrointestinal tissues of mice that received gut homing T cells correlated with lower inflammation and gut damage early post-transplant, decreased graft-versus-host disease severity, and prolonged survival compared with those receiving control transduced regulatory T cells. These data provide evidence that enforced targeting of ex vivo expanded regulatory T cells to the gastrointestinal tract diminishes gut injury and is associated with decreased graft-versus-host disease severity.

Phase II, Open-Label Clinical Trial of Urinary-Derived Human Chorionic Gonadotropin/Epidermal Growth Factor for Life-Threatening Acute Graft-versus-Host Disease

Treatments that aid inflammation resolution, immune tolerance, and epithelial repair may improve outcomes beyond high-dose corticosteroids and other broad immunosuppressants for life-threatening acute graft-versus-host disease (aGVHD). We studied the addition of urinary-derived human chorionic gonadotropin/epidermal growth factor (uhCG/EGF; Pregnyl; Organon, Jersey City, NJ) to standard aGVHD therapy in a prospective Phase II clinical trial (ClinicalTrials.gov identifier NCT02525029). Twenty-two patients with Minnesota (MN) high-risk aGVHD received methylprednisolone 48 mg/m2/day plus 2000 units/m2 of uhCG/EGF s.c. every other day for 1 week. Patients requiring second-line aGVHD therapy received uhCG/EGF 2000 to 5000 units/m2 s.c. every other day for 2 weeks plus standard of care immunosuppression (physician's choice). Responding patients were eligible to receive maintenance doses twice weekly for 5 weeks. Immune cell subsets in peripheral blood were evaluated by mass cytometry and correlated with plasma amphiregulin (AREG) level and response to therapy. Most patients had stage 3-4 lower gastrointestinal tract GVHD (52%) and overall grade III-IV aGVHD (75%) at time of enrollment. The overall proportion of patients with a response at day 28 (primary endpoint) was 68% (57% with complete response, 11% with partial response). Nonresponders had higher baseline counts of KLRG1+ CD8 cells and T cell subsets expressing TIM-3. Plasma AREG levels remained persistently elevated in nonresponders and correlated with AREG expression on peripheral blood T cells and plasmablasts. The addition of uhCG/EGF to standard therapy is a feasible supportive care measure for patients with life-threatening aGVHD. As a commercially available, safe, and inexpensive drug, uhCG/EGF added to standard therapy may reduce morbidity and mortality from severe aGVHD and merits further study.

Murine cytomegalovirus reactivation concomitant with acute graft-versus-host disease is controlled by antibodies

Reactivation of human cytomegalovirus (HCMV) from latency is a frequent complication following hematopoietic stem cell transplantation (HSCT). The development of acute graft-versus-host disease (GVHD) is a significant risk factor for HCMV disease. Using a murine GVHD model in animals latently infected with murine CMV (MCMV), we studied preventive and therapeutic interventions in this high-risk scenario of HSCT. Mice latently infected with MCMV experienced reactivated MCMV and developed disseminated MCMV infection concomitant with the manifestations of GVHD. Dissemination was accompanied by accelerated mortality. We demonstrate that MCMV reactivation and dissemination was modulated by MCMV-specific antibodies, thus demonstrating in vivo protective activity of antiviral antibodies. However, the efficacy of serum therapy required repetitive doses of high-titer immune serum secondary to the shortened serum half-life of IgG in animals with GVHD. In a complementary approach, treatment of GVHD by adoptive transfer of donor-derived Tregs facilitated production of MCMV-specific antibodies from newly developing donor-derived B cells. Together, our findings strongly suggest that antibodies play a major role in controlling recurrent MCMV infection that follows GVHD, and they argue for reassessing the potential of antibody treatments as well as therapeutic strategies that enhance de novo antibody development against HCMV.

Harmonizing Definitions for Diagnostic Criteria and Prognostic Assessment of Transplantation-Associated Thrombotic Microangiopathy: A Report on Behalf of the European Society for Blood and Marrow Transplantation, American Society for Transplantation and Cellular Therapy, Asia-Pacific Blood and Marrow Transplantation Group, and Center for International Blood and Marrow Transplant Research

Transplantation-associated thrombotic microangiopathy (TA-TMA) is an increasingly recognized complication of hematopoietic cell transplantation (HCT) associated with significant morbidity and mortality. However, TA-TMA is a clinical diagnosis, and multiple criteria have been proposed without universal application. Although some patients have a self-resolving disease, others progress to multiorgan failure and/or death. Poor prognostic features also are not uniformly accepted. The lack of harmonization of diagnostic and prognostic markers has precluded multi-institutional studies to better understand incidence and outcomes. Even current interventional trials use different criteria, making it challenging to interpret the data. To address this urgent need, the American Society for Transplantation and Cellular Therapy, Center for International Bone Marrow Transplant Research, Asia-Pacific Blood and Marrow Transplantation, and European Society for Blood and Marrow Transplantation nominated representatives for an expert panel tasked with reaching consensus on diagnostic and prognostic criteria. The panel reviewed literature, generated consensus statements regarding diagnostic and prognostic features of TA-TMA using the Delphi method, and identified future directions of investigation. Consensus was reached on 4 key concepts: (1) TA-TMA can be diagnosed using clinical and laboratory criteria or tissue biopsy of kidney or gastrointestinal tissue; however, biopsy is not required; (2) consensus diagnostic criteria are proposed using the modified Jodele criteria with additional definitions of anemia and thrombocytopenia. TA-TMA is diagnosed when ≥4 of the following 7 features occur twice within 14 days: anemia, defined as failure to achieve transfusion independence despite neutrophil engraftment; hemoglobin decline by ≥1 g/dL or new-onset transfusion dependence; thrombocytopenia, defined as failure to achieve platelet engraftment, higher-than-expected transfusion needs, refractory to platelet transfusions, or ≥50% reduction in baseline platelet count after full platelet engraftment; lactate dehydrogenase (LDH) exceeding the upper limit of normal (ULN); schistocytes; hypertension; soluble C5b-9 (sC5b-9) exceeding the ULN; and proteinuria (≥1 mg/mg random urine protein-to-creatinine ratio [rUPCR]); (3) patients with any of the following features are at increased risk of nonrelapse mortality and should be stratified as high-risk TA-TMA: elevated sC5b-9, LDH ≥2 times the ULN, rUPCR ≥1 mg/mg, multiorgan dysfunction, concurrent grade II-IV acute graft-versus-host disease (GVHD), or infection (bacterial or viral); and (4) all allogeneic and pediatric autologous HCT recipients with neuroblastoma should be screened weekly for TA-TMA during the first 100 days post-HCT. Patients diagnosed with TA-TMA should be risk-stratified, and those with high-risk disease should be offered participation in a clinical trial for TA-TMA-directed therapy if available. We propose that these criteria and risk stratification features be used in data registries, prospective studies, and clinical practice across international settings. This harmonization will facilitate the investigation of TA-TMA across populations diverse in race, ethnicity, age, disease indications, and transplantation characteristics. As these criteria are widely used, we expect continued refinement as necessary. Efforts to identify more specific diagnostic and prognostic biomarkers are a top priority of the field. Finally, an investigation of the impact of TA-TMA-directed treatment, particularly in the setting of concurrent highly morbid complications, such as steroid-refractory GVHD and infection, is critically needed.

JAK1/2 inhibitor ruxolitinib promotes the expansion and suppressive action of polymorphonuclear myeloid-derived suppressor cells via the JAK/STAT and ROS-MAPK/NF-κB signalling pathways in acute graft-versus-host disease

Objectives

Ruxolitinib, a Janus kinase (JAK) 1/2 inhibitor, demonstrates efficacy for treating steroid-resistant acute graft-versus-host disease (SR-aGVHD) following allogeneic stem cell transplantation (allo-HSCT). Myeloid-derived suppressor cells (MDSCs) have a protective effect on aGVHD via suppressing T cell function. However, the precise features and mechanism of JAK inhibitor-mediated immune modulation on MDSCs subsets remain poorly understood.

Methods

A total of 74 SR-aGVHD patients treated with allo-HSCT and ruxolitinib were enrolled in the present study. The alterations of MDSC and regulatory T cell (Treg) populations were monitored during ruxolitinib treatment in responders and nonresponders. A mouse model of aGVHD was used to evaluate the immunosuppressive activity of MDSCs and related signalling pathways in response to ruxolitinib administration in vivo and in vitro.

Results

Patients with SR-aGVHD who received ruxolitinib treatment achieved satisfactory outcomes. Elevation proportions of MDSCs before treatment, especially polymorphonuclear-MDSCs (PMN-MDSCs) were better to reflect the response to ruxolitinib than those in Tregs. In the mouse model of aGVHD, the administration of ruxolitinib resulted in the expansion and functional enhancement of PMN-MDSCs and the effects could be partially reversed by an anti-Gr-1 antibody in vivo. Ruxolitinib treatment significantly elevated the suppressive function of PMN-MDSCs through reactive oxygen species (ROS) production by Nox2 upregulation as well as bypassing the activated MAPK/NF-κB signalling pathway. Additionally, ex vivo experiments demonstrated that ruxolitinib prevented the differentiation of mature myeloid cells and promoted the accumulation of MDSCs by inhibiting STAT5.

Conclusions

Ruxolitinib enhances PMN-MDSCs functions through JAK/STAT and ROS-MAPK/NF-κB signalling pathways. Monitoring frequencies and functions of MDSCs can help evaluate treatment responses to ruxolitinib.

ROCKETS - a novel one-for-all toolbox for light sheet microscopy in drug discovery

Advancing novel immunotherapy strategies requires refined tools in preclinical research to thoroughly assess drug targets, biodistribution, safety, and efficacy. Light sheet fluorescence microscopy (LSFM) offers unprecedented fast volumetric ex vivo imaging of large tissue samples in high resolution. Yet, to date laborious and unstandardized tissue processing procedures have limited throughput and broader applications in immunological research. Therefore, we developed a simple and harmonized protocol for processing, clearing and imaging of all mouse organs and even entire mouse bodies. Applying this Rapid Optical Clearing Kit for Enhanced Tissue Scanning (ROCKETS) in combination with LSFM allowed us to comprehensively study the in vivo biodistribution of an antibody targeting Epithelial Cell Adhesion Molecule (EpCAM) in 3D. Quantitative high-resolution scans of whole organs did not only reveal known EpCAM expression patterns but, importantly, uncovered several new EpCAM-binding sites. We identified gustatory papillae of the tongue, choroid plexi in the brain and duodenal papillae as previously unanticipated locations of high EpCAM expression. Subsequently, we confirmed high EpCAM expression also in human tongue and duodenal specimens. Choroid plexi and duodenal papillae may be considered as particularly sensitive sites due to their importance for liquor production or as critical junctions draining bile and digestive pancreatic enzymes into the small bowel, respectively. These newly gained insights appear highly relevant for clinical translation of EpCAM-addressing immunotherapies. Thus, ROCKETS in combination with LSFM may help to set new standards for preclinical evaluation of immunotherapeutic strategies. In conclusion, we propose ROCKETS as an ideal platform for a broader application of LSFM in immunological research optimally suited for quantitative co-localization studies of immunotherapeutic drugs and defined cell populations in the microanatomical context of organs or even whole mice.

Statin-based endothelial prophylaxis and outcome after allogeneic stem cell transplantation

BACKGROUND

Allogeneic haematopoietic stem cell transplantation (alloSCT) often remains the only curative therapy for hematologic malignancies. Although the management of transplant-associated adverse events considerably improved over the last decades, nonrelapse mortality (NRM) remains a challenge, and endothelial dysfunction was identified as a major contributor to NRM.

METHODS

Statin-based endothelial prophylaxis (SEP) has been implemented in the standard of care in our transplant centre to reduce NRM caused by endothelial injury. Here, we retrospectively analysed the impact of SEP on clinical outcome in a cohort of 347 alloSCT patients.

RESULTS

SEP (n = 209) was associated with significantly reduced NRM (hazard ratio 0.61, 95% CI 0.38-0.96) and better overall survival (OS) after acute graft-versus-host disease (HR 0.59, 95% CI 0.37-0.93). Subgroup analyses showed that the NRM benefit was mainly found in patients with an intermediate endothelial activation and stress index (EASIX), while relapse risk was not affected. On day 100 post-alloSCT, patients receiving SEP had significantly higher levels of the rate-limiting enzyme of tryptophan metabolism, indoleamine 2,3-dioxygenase (IDO), higher kynurenine to tryptophan ratios as a proxy of IDO activity and tended to have lower levels of the endothelial injury marker ST2 (p = .055). No significant differences in interferon-gamma or IL18 levels were observed. These biomarker signatures suggest that the beneficial effects of SEP might be mediated by both endothelial protection and immunomodulation.

CONCLUSIONS

Together, these data suggest that SEP improves NRM and OS post-alloSCT in particular in patients with intermediate endothelial risk and provide first mechanistic clues about its potential mode of action.

Recent advances in graft-versus-host disease

Acute and chronic graft-versus-host disease (GVHD) continue to present a significant challenge to physicians, accounting for considerable haematopoietic stem cell transplant (HSCT)-related morbidity and mortality, particularly those patients with steroid-refractory disease. In this review, we discuss recent advances in understanding the underlying pathophysiology, prevention and management of acute and chronic GVHD. Barriers to progress include the difficulty in obtaining high-quality evidence with sufficient patient numbers to identify optimal preventative and treatment strategies, with the heterogeneity of multiple patient, donor, graft and transplant-related factors, in addition to limited availability of human tissue to study the underlying pathophysiology, particularly in steroid-refractory disease. Continued collaborative efforts to improve our understanding of the pathophysiology involved, particularly in steroid-refractory disease, identification of biomarkers to permit risk stratification, and further well-designed randomised clinical trials are essential to help physicians determine optimal GVHD preventative and treatment strategies for each individual patient.

EPC infusion ameliorates acute graft-versus-host disease-related endothelial injury after allogeneic bone marrow transplantation

Introduction

Graft-versus-host disease (GVHD) damages vascular endothelium. Endothelial progenitor cell (EPC) can differentiate to endothelial cell and promote angiogenesis, but its role in endothelial damage in GVHD is unclear.

Methods

In this study, we intend to assess whether EPC infusion promotes the repair of endothelial injury in GVHD mouse model. Male BALB/c mice were randomly divided into 5 groups: control group, total body irradiation group (TBI group), allogeneic bone marrow transplantation group (Allo-BMT group), acute graft versus host disease group (GVHD group), EPC infusion group (GVHD+EPC group) followed by analysis of mice survival, acute GVHD (aGVHD) score, T cell infiltration by immunofluorescence, as well as continuity of vascular endothelium in liver.

Results

Compared with Allo-BMT group, the clinical and pathological score of aGVHD mice were higher. On day 21 after transplantation, a large number of mononuclear cell infiltrations were seen in the target tissues of aGVHD mice and mice died within 30 days. In addition, aGVHD group also presented increased subendothelial infiltration of CD3+ T cells in the liver, decreased VE-cadherin expression and elevated major histocompatibility complex (MHC) II molecule expression in the endothelium. Moreover, expression of MHC-II molecule increased in endothelial cell after irradiation injury and LPS stimulation, indicating abnormally activated endothelial cell with antigen-presenting function. Interestingly, infusion of EPC reduced the clinical and pathological score of aGVHD, decreased infiltration of mononuclear cells, improved survival as well as upregulated VE-cadherin and downregulated MHC-II molecule.

Discussion

EPC infusion can mobilize to affected endothelium to decrease the infiltration of T cells and pathological endothelial activation contributing to ameliorating the damage of endothelium. EPC infusion combined with bone marrow transplantation might be a perspective strategy for the prevention and treatment of aGVHD.

Role of endothelial cells in graft-versus-host disease

To date, the only curative treatment for high-risk or refractory hematologic malignancies non-responsive to standard chemotherapy is allogeneic hematopoietic transplantation (allo-HCT). Acute graft-versus-host disease (GVHD) is a donor T cell-mediated immunological disorder that is frequently fatal and the leading cause of non-relapse mortality (NRM) in patients post allo-HCT. The pathogenesis of acute GVHD involves recognition of minor and/or major HLA mismatched host antigens by donor T cells followed by expansion, migration and finally end-organ damage due to combination of inflammatory cytokine secretion and direct cytotoxic effects. The endothelium is a thin layer of endothelial cells (EC) that line the innermost portion of the blood vessels and a key regulator in vascular homeostasis and inflammatory responses. Endothelial cells are activated by a wide range of inflammatory mediators including bacterial products, contents released from dying/apoptotic cells and cytokines and respond by secreting cytokines/chemokines that facilitate the recruitment of innate and adaptive immune cells to the site of inflammation. Endothelial cells can also be damaged prior to transplant as well as by alloreactive donor T cells. Prolonged EC activation results in dysfunction that plays a role in multiple post-transplant complications including but not limited to veno-occlusive disease (VOD), transplant associated thrombotic microangiopathy (TA-TMA), and idiopathic pneumonia syndrome. In this mini review, we summarize the biology of endothelial cells, factors regulating EC activation and the role of ECs in inflammation and GVHD pathogenesis.

The Clinical Value of Procalcitonin in the Neutropenic Period After Allogeneic Hematopoietic Stem Cell Transplantation

The diagnostic value of procalcitonin and the prognostic role of PCT clearance remain unclear in neutropenic period after allogeneic hematopoietic stem cell transplantation introduction. This study evaluated 219 febrile neutropenic patients (116, retrospectively; 103, prospectively) who underwent allo-HSCT from April 2014 to March 2016. The area under the receiver operator characteristic curve (AUC) of PCT for detecting documented infection (DI) was 0.637, and that of bloodstream infection (BSI) was 0.811. In multivariate analysis, the inability to decrease PCT by more than 80% within 5–7 days after the onset of fever independently predicted poor 100-day survival following allo-HSCT (P = 0.036). Furthermore, the prognostic nomogram combining PCTc and clinical parameters showed a stable predictive performance, supported by the C-index of 0.808 and AUC of 0.813 in the primary cohort, and C-index of 0.691 and AUC of 0.697 in the validation cohort. This study demonstrated the diagnostic role of PCT in documented and bloodstream infection during the neutropenic period after allo-HSCT. PCTc might serve as a predictive indicator of post-HSCT 100-day mortality. A nomogram based on PCTc and several clinical factors effectively predicted the 100-day survival of febrile patients and may help physicians identify high-risk patients in the post-HSCT neutropenic period.

Early vascular endothelial complications after hematopoietic cell transplantation: Role of the endotheliopathy in biomarkers and target therapies development

This work aims to review the role of endothelial dysfunction underlying the main complications appearing early after autologous and allogeneic hematopoietic cell transplantation (HCT). The endothelial damage as the pathophysiological substrate of sinusoidal obstruction syndrome (SOS) is well established. However, there is growing evidence of the involvement of endothelial dysfunction in other complications, such as acute graft-versus-host disease (aGVHD) and transplant-associated thrombotic microangiopathy (TA-TMAs). Moreover, HCT-related endotheliopathy is not only limited to the HCT setting, as there is increasing evidence of its implication in complications derived from other cellular therapies. We also review the incidence and the risk factors of the main HCT complications and the biological evidence of the endothelial involvement and other linked pathways in their development. In addition, we cover the state of the art regarding the potential use of the biomarkers of endotheliopathy in the prediction, the early diagnosis, and the follow-up of the HCT complications and summarize current knowledge points to the endothelium and the other linked pathways described as potential targets for the prevention and treatment of HCT-complications. Lastly, the endothelium-focused therapeutic strategies that are emerging and might have a potential impact on the survival and quality of life of post-HCT-patients are additionally reviewed.

Oridonin prevents oxidative stress-induced endothelial injury via promoting Nrf-2 pathway in ischaemic stroke

Oridonin, a natural diterpenoid compound extracted from a Chinese herb, has been proved to exert anti‐oxidative stress effects in various disease models. The aim of the present study was to investigate the protective effects of oridonin on oxidative stress‐induced endothelial injury in ischaemic stroke. We found oridonin repaired blood‐brain barrier (BBB) integrity presented with upregulation of tight junction proteins (TJ proteins) expression, inhibited the infiltration of periphery inflammatory cells and neuroinflammation and thereby reduced infarct volume in ischaemic stroke mice. Furthermore, our results showed that oridonin could protect against oxidative stress‐induced endothelial injury via promoting nuclear translocation of nuclear factor‐erythroid 2 related factor 2 (Nrf‐2). The specific mechanism could be the activation of AKT(Ser473)/GSK3β(Ser9)/Fyn signalling pathway. Our findings revealed the therapeutic effect and mechanism of oridonin in ischaemic stroke, which provided fundamental evidence for developing the extracted compound of Chinese herbal medicine into an innovative drug for ischaemic stroke treatment.

Biomarkers for Early Complications of Endothelial Origin After Allogeneic Hematopoietic Stem Cell Transplantation: Do They Have a Potential Clinical Role?

Endothelial cell (EC) dysfunction causes a number of early and life-threatening post hematopoietic stem cell transplant (HCT) complications that result in a rapid clinical decline. The main early complications are graft-vs.-host disease (GVHD), transplant associated thrombotic microangiopathy (TA-TMA), and sinusoidal obstruction syndrome (SOS). Post-HCT endothelial dysfunction occurs as a result of chemotherapy, infections, and allogeneic reactivity. Despite major advances in transplant immunology and improvements in supportive care medicine, these complications represent a major obstacle for successful HCT. In recent years, different biomarkers have been investigated for early detection of post-transplant endothelial cell dysfunction, but few have been validated. In this review we will define GVHD, TA-TMA and SOS, summarize the current data available in HCT biomarker research and identify promising biomarkers for detection and diagnosis of early HCT complications.

Von Willebrand Factor, Factor VIII, and Other Acute Phase Reactants as Biomarkers of Inflammation and Endothelial Dysfunction in Chronic Graft-Versus-Host Disease

Chronic graft-versus-host disease (cGvHD) is an immune mediated late complication of allogeneic hematopoietic stem cell transplantation (alloHSCT). Discovery of adequate biomarkers could identify high-risk patients and provide an effective pre-emptive intervention or early modification of therapeutic strategy, thus reducing prevalence and severity of the disease among long-term survivors of alloHSCT. Inflammation, endothelial injury, and endothelial dysfunction are involved in cGvHD development. Altered levels of acute phase reactants have shown a strong correlation with the activity of several immune mediated disorders and are routinely used in clinical practice. Since elevated von Willebrand factor (VWF) and factor VIII (FVIII) levels have been described as acute phase reactants that may indicate endothelial dysfunction and inflammation in different settings, including chronic autoimmune diseases, they could serve as potential candidate biomarkers of cGvHD. In this review we focused on reported data regarding VWF and FVIII as well as other markers of inflammation and endothelial dysfunction, evaluating their potential role in cGvHD.