Encephalitis and GABAB receptor antibodies: novel findings in a new case series of 20 patients

OBJECTIVE

To report the clinical features of 20 newly diagnosed patients with GABAB receptor (GABABR) antibodies and determine the frequency of associated tumors and concurrent neuronal autoantibodies.

METHODS

Clinical data were retrospectively obtained and evaluated. Serum and CSF samples were examined for additional antibodies using methods previously reported.

RESULTS

Seventeen patients presented with seizures, memory loss, and confusion, compatible with limbic encephalitis (LE), one patient presented with ataxia, one patient presented with status epilepticus, and one patient presented with opsoclonus-myoclonus syndrome (OMS). Nineteen (95%) patients eventually developed LE during the course of the disease. Small-cell lung cancer (SCLC) was identified in 10 (50%) patients, all with LE. Treatment and outcome was available from 19 patients: 15 showed complete (n = 7) or partial (n = 8) neurologic improvement after steroids, IV immunoglobulins, or plasma exchange and oncologic treatment when indicated; 1 patient died of tumor progression shortly after the first cycle of immunotherapy, and 3 were not treated. Five patients with SCLC had additional onconeuronal antibodies (Ri, amphiphysin, or SOX1), and 2 without tumor had GAD65 and NMDAR antibodies, respectively. GABABR antibodies were not detected in serum of 116 patients with SCLC without neurologic symptoms.

CONCLUSION

Our study confirms GABABR as an autoantigen of paraneoplastic and nonparaneoplastic LE and expands the phenotype of GABABR antibodies to ataxia, OMS, and status epilepticus. The long-term prognosis is dictated by the presence of a tumor. Recognition of syndromes associated with GABABR antibodies is important because they usually respond to treatment.

Alpha-Gal on bioprostheses: xenograft immune response in cardiac surgery

BACKGROUND

The alpha-Gal (Galalpha1,3-Galbeta1-4GlcNAc-R) epitope is the major xenoantigen causing hyperacute rejection of pig organs transplanted into primates. Porcine bioprostheses are utilized in cardiac surgery. However, premature degeneration of bioprostheses has limited utilization in younger patients and the immune response remains elusive. We sought to investigate whether a specific alpha-Gal immune response may play a role in this clinical scenario.

MATERIALS AND METHODS

We investigated the presence of alpha-Gal-epitope on native and fixed porcine valves by means of confocal laser scanning microscope (CLSM). ELISA was utilized to evidence whether implantation of bioprostheses elicits augmentation of pre-existing cytotoxic anti alpha-Gal IgM antibodies within 10 days of surgery. Patients who underwent coronary artery bypass grafting (CABG) or mechanical valve replacement served as controls (each group, n = 12). To corroborate the clinical relevance of the alpha-Gal immune response in vivo, we studied serum obtained before and after implantation of bioprostheses and its potency to lyse porcine alpha-Gal-bearing PK15 cells.

RESULTS

We found the immunogenic alpha-Gal-epitope on fibrocytes interspersed in the connective tissue of porcine valves as determined by vimentin/IB4 lectin binding. Moreover, patients who were provided with a bioprostheses had developed a significant increase of naturally occurring cytotoxic IgM antibodies directed towards alpha-Gal after surgical intervention as compared with control patients (P < 0.0001, respectively). Sera obtained from the patients after the implantation of bioprostheses demonstrated an increased cytotoxicity against alpha-Gal-bearing PK-15 cells as compared with preoperative sera (P < 0.001). The specificity of the cytotoxic effects was proven as soluble Galalpha1-3Galbeta1-4GlcNAc markedly inhibited cell death of alpha-Gal-bearing PK15 cells (P < 0.001).

CONCLUSION

Our data suggest that implantation of bioprostheses in cardiac surgery induces a xenograft-specific immune response. Procedures diminishing the presence of alpha-Gal on bioprostheses, such as utilization of genetically manipulated alpha-Gal-deficient xenograft or pretreatment with alpha-Galactosidase, might diminuate the immune response against bioprostheses and extend durability.

Activation-induced T-cell death and immune dysfunction after implantation of left-ventricular assist device

BACKGROUND

Cardiac transplantation is a limited option for end-stage heart failure because of the shortage of donor organs. Left-ventricular assist devices (LVADs) are currently under investigation as permanent therapy for end-stage heart failure, but long-term successful device implantation is limited because of a high rate of serious infections. To examine the relation between LVAD-related infection and host immunity, we investigated immune responses in LVAD recipients.

METHODS

We compared the rate of candidal infection in 78 patients with New York Heart Association class IV heart failure who received either an LVAD (n=40) or medical management (controls, n=38). Fluorochrome-labelled monoclonal antibodies were used in analyses of T-cell phenotype. Analysis of T-cell function included intradermal responses to recall antigens and proliferative responses after stimulation by phytohaemagglutinin, monoclonal antibodies to CD3, and mixed lymphocyte culture. We measured T-cell apoptosis in vivo by annexin V binding, and confirmed the result by assessment of DNA fragmentation. Activation-induced T-cell death was measured after T-cell stimulation with antibodies to CD3. All immunological tests were done at least 1 month after LVAD implantation. Between-group comparisons were by Kaplan-Meier actuarial analysis and Student's t test.

FINDINGS

By 3 months after implantation of LVAD, the risk of developing candidal infection was 28% in LVAD recipients, compared with 3% in controls (p=0.003). LVAD recipients had cutaneous anergy to recall antigens and lower (<70%) T-cell proliferative responses than controls after activation via the T-cell receptor complex (p<0.001). T cells from LVAD recipients had higher surface expression of CD95 (Fas) (p<0.001) and a higher rate of spontaneous apoptosis (p<0.001) than controls. Moreover, after stimulation with antibodies to CD3, CD4 T-cell death increased by 3.2-fold in LVAD recipients compared with only 1.2-fold in controls (p<0.05).

INTERPRETATION

LVAD implantation results in an aberrant state of T-cell activation, heightened susceptibility of CD4 T cells to activation-induced cell death, progressive defects in cellular immunity, and increased risk of opportunistic infection.

Increased levels of soluble ST2 protein and IgG1 production in patients with sepsis and trauma

OBJECTIVE

T1/ST2, a member of the interleukin (IL)-1 receptor superfamily, is predominantly expressed on type-2 T helper (Th2) cells but not Th1 cells, and plays a role in cell proliferation and Th2 immune response. The relation of soluble ST2, Th1-Th2 cytokine profile, and immunoglobulin (Ig) production in sepsis and trauma patients is not well known.

DESIGN AND SETTING

Case-control study at a university hospital intensive care unit.

PATIENTS

Fifteen patients recruited within 24-48 h of diagnosis of sepsis, 13 trauma patients recruited within 24 h after admission to the ICU, 11 patients who underwent abdominal surgery, and 15 healthy volunteers served as control.

MEASUREMENTS AND RESULTS

ELISA was utilized to detect serum soluble ST2, IL-2, IFN-gamma, IL-10, and Ig production. Serum levels of soluble ST2 were significantly increased in septic patients (8420+/-2169 pg/ml) as compared with trauma (2936+/-826 pg/ml), abdominal surgery (1423+/-373 pg/ml), and healthy controls (316+/-72 pg/ml; p<0.001, respectively). These results were accompanied by an increase of IgG1 and IgG2 production, and decrease of IL-2 and IFN-gamma synthesis in septic patients. IL-10 was significantly increased in both septic and trauma patients.

CONCLUSIONS

Our results demonstrate that soluble ST2, a marker for Th2 cytokine producing cells, is increased in sepsis and trauma patients, and they provide further evidence for a shift from Th1- to Th2-biased cells.

Deciphering the functional heterogeneity of skin fibroblasts using single-cell RNA sequencing

Though skin fibroblasts (FB) are the main cell population within the dermis, the different skin FB subsets are not well characterized and the traditional classification into reticular and papillary FBs has little functional relevance. To fill the gap of knowledge on FB diversity in human skin, we performed single-cell RNA sequencing. Investigation of marker genes for the different skin cell subtypes revealed a heterogeneous picture of FBs. When mapping reticular and papillary FB markers, we could not detect cluster specificity, suggesting that these two populations show a higher transcriptional heterogeneity than expected. This finding was further confirmed by in situ hybridization, showing that DPP4 was expressed in both dermal layers. Our analysis identified six FB clusters with distinct transcriptional signatures. Importantly, we could demonstrate that in human skin DPP4⁺ FBs are the main producers of factors involved in extracellular matrix (ECM) assembly. In conclusion, we provide evidence that hitherto considered FB markers are not ideal to characterize skin FB subpopulations in single-cell sequencing analyses. The identification of DPP4⁺ FBs as the main ECM-producing cells in human skin will foster the development of anti-fibrotic treatments for the skin and other organs.

Secretome of apoptotic peripheral blood cells (APOSEC) confers cytoprotection to cardiomyocytes and inhibits tissue remodelling after acute myocardial infarction: a preclinical study

Heart failure following acute myocardial infarction (AMI) is a major cause of morbidity and mortality. Our previous observation that injection of apoptotic peripheral blood mononuclear cell (PBMC) suspensions was able to restore long-term cardiac function in a rat AMI model prompted us to study the effect of soluble factors derived from apoptotic PBMC on ventricular remodelling after AMI. Cell culture supernatants derived from irradiated apoptotic peripheral blood mononuclear cells (APOSEC) were collected and injected as a single dose intravenously after myocardial infarction in an experimental AMI rat model and in a porcine closed chest reperfused AMI model. Magnetic resonance imaging (MRI) and echocardiography were used to quantitate cardiac function. Analysis of soluble factors present in APOSEC was performed by enzyme-linked immunosorbent assay (ELISA) and activation of signalling cascades in human cardiomyocytes by APOSEC in vitro was studied by immunoblot analysis. Intravenous administration of a single dose of APOSEC resulted in a reduction of scar tissue formation in both AMI models. In the porcine reperfused AMI model, APOSEC led to higher values of ejection fraction (57.0 vs. 40.5%, p < 0.01), a better cardiac output (4.0 vs. 2.4 l/min, p < 0.001) and a reduced extent of infarction size (12.6 vs. 6.9%, p < 0.02) as determined by MRI. Exposure of primary human cardiac myocytes with APOSEC in vitro triggered the activation of pro-survival signalling-cascades (AKT, Erk1/2, CREB, c-Jun), increased anti-apoptotic gene products (Bcl-2, BAG1) and protected them from starvation-induced cell death. Intravenous infusion of culture supernatant of apoptotic PBMC attenuates myocardial remodelling in experimental AMI models. This effect is probably due to the activation of pro-survival signalling cascades in the affected cardiomyocytes.

Blockade of RAGE suppresses alloimmune reactions in vitro and delays allograft rejection in murine heart transplantation

The receptor for advanced glycation endproducts (RAGE), a multiligand member of the immunoglobulin superfamily, interacts with proinflammatory AGEs, the products of nonenzymatic glycation and oxidation of proteins; high-mobility group box 1 (HMGB1), also known as amphoterin and S100/calgranulins to amplify inflammation and tissue injury. Previous studies showed that blockade of RAGE suppressed recruitment of proinflammatory mechanisms in murine models. We tested the hypothesis that RAGE contributes to alloimmune responses and report that in vivo, acute rejection of fully allogeneic cardiac allografts in a murine model of heterotopic cardiac transplantation is significantly delayed by pharmacological antagonism of RAGE. In parallel, allogeneic T-cell proliferation in the mixed lymphocyte reaction is, at least in part, RAGE-dependent. These data provide the first insights into key roles for RAGE in allorecognition responses and suggest that antagonism of this receptor may exert beneficial effects in allogeneic organ transplantation.

Heightened levels of circulating 20S proteasome in critically ill patients

BACKGROUND

Recently, circulating proteasome core particles (20S proteasome) have been suggested as a marker of cell damage and immunological activity in autoimmune diseases. Aberrant leucocyte activation and increased lymphocyte apoptosis with consecutive T-cell unresponsiveness is deemed to play a pivotal role in the sepsis syndrome. Moreover sepsis-induced muscle proteolysis mainly reflects ubiqutin proteasome-dependent protein degradation. We therefore sought to investigate serum levels of 20S proteasome in critical ill patients.

MATERIAL AND METHODS

Case-control-study at a university hospital intensive care unit; 15 patients recruited within 24-48 h of diagnosis of sepsis, 13 trauma patients recruited within 24 h of admission to the ICU, a control group of 15 patients who underwent abdominal surgery, and 15 healthy volunteers. ELISA was used to measure the concentration of 20S proteasome in the sera of the patients and controls. Data are given as mean +/- SEM. Mann-Whitney U-test was used to calculate significance and a P-value of 0.05 was considered to be statistically significant.

RESULTS

Marked increase of 20S proteasome was detected in the sera of septic patients (33 551 +/- 10 034 ng mL-1) as well as in trauma patients (29 669 +/- 5750 ng mL-1). In contrast, significantly lower concentrations were found in the abdominal surgery group (4661 +/- 1767 ng mL-1) and in the healthy control population (2157 +/- 273 ng mL-1).

CONCLUSION

Detection of 20S proteasome may represent a novel marker of immunological activity and muscle degradation in sepsis and trauma patients, and may be useful in monitoring the clinical effect of proteasome-inhibitors.

Peripheral blood mononuclear cell secretome for tissue repair

For almost two decades, cell-based therapies have been tested in modern regenerative medicine to either replace or regenerate human cells, tissues, or organs and restore normal function. Secreted paracrine factors are increasingly accepted to exert beneficial biological effects that promote tissue regeneration. These factors are called the cell secretome and include a variety of proteins, lipids, microRNAs, and extracellular vesicles, such as exosomes and microparticles. The stem cell secretome has most commonly been investigated in pre-clinical settings. However, a growing body of evidence indicates that other cell types, such as peripheral blood mononuclear cells (PBMCs), are capable of releasing significant amounts of biologically active paracrine factors that exert beneficial regenerative effects. The apoptotic PBMC secretome has been successfully used pre-clinically for the treatment of acute myocardial infarction, chronic heart failure, spinal cord injury, stroke, and wound healing. In this review we describe the benefits of choosing PBMCs instead of stem cells in regenerative medicine and characterize the factors released from apoptotic PBMCs. We also discuss pre-clinical studies with apoptotic cell-based therapies and regulatory issues that have to be considered when conducting clinical trials using cell secretome-based products. This should allow the reader to envision PBMC secretome-based therapies as alternatives to all other forms of cell-based therapies.

Irradiated cultured apoptotic peripheral blood mononuclear cells regenerate infarcted myocardium

BACKGROUND

Acute myocardial infarction (AMI) is followed by post AMI cardiac remodelling, often leading to congestive heart failure. Homing of c-kit+ endothelial progenitor cells (EPC) has been thought to be the optimal source for regenerating infarcted myocardium.

METHODS

Immune function of viable peripheral blood mononuclear cells (PBMC) was evaluated after co-culture with irradiated apoptotic PBMC (IA-PBMC) in vitro. Viable PBMC, IA-PBMC and culture supernatants (SN) thereof were obtained after 24 h. Reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay were utilized to quantify interleukin-8 (IL-8), vascular endothelial growth factor, matrix metalloproteinase-9 (MMP9) in PBMC, SN and SN exposed fibroblasts. Cell suspensions of viable- and IA-PBMC were infused in an experimental rat AMI model. Immunohistological analysis was performed to detect inflammatory and pro-angiogenic cells within 72 h post-infarction. Functional data and determination of infarction size were quantified by echocardiography and Elastica van Gieson staining.

RESULTS

The IA-PBMC attenuated immune reactivity and resulted in secretion of pro-angiogenic IL-8 and MMP9 in vitro. Fibroblasts exposed to viable and IA-PBMC derived SN caused RNA increment of IL-8 and MMP9. AMI rats that were infused with IA-PBMC cell suspension evidenced enhanced homing of endothelial progenitor cells within 72 h as compared to control (medium alone, viable-PBMC). Echocardiography showed a significant reduction in infarction size and improvement in post AMI remodelling as evidenced by an attenuated loss of ejection fraction.

CONCLUSION

These data indicate that infusion of IA-PBMC cell suspension in experimental AMI circumvented inflammation, caused preferential homing of regenerative EPC and replaced infarcted myocardium.

Intravenous and intramyocardial injection of apoptotic white blood cell suspensions prevents ventricular remodelling by increasing elastin expression in cardiac scar tissue after myocardial infarction

Congestive heart failure developing after acute myocardial infarction (AMI) is a major cause of morbidity and mortality. Clinical trials of cell-based therapy after AMI evidenced only a moderate benefit. We could show previously that suspensions of apoptotic peripheral blood mononuclear cells (PBMC) are able to reduce myocardial damage in a rat model of AMI. Here we experimentally examined the biochemical mechanisms involved in preventing ventricular remodelling and preserving cardiac function after AMI. Cell suspensions of apoptotic cells were injected intravenously or intramyocardially after experimental AMI induced by coronary artery ligation in rats. Administration of cell culture medium or viable PBMC served as controls. Immunohistological analysis was performed to analyse the cellular infiltrate in the ischaemic myocardium. Cardiac function was quantified by echocardiography. Planimetry of the infarcted hearts showed a significant reduction of infarction size and an improvement of post AMI remodelling in rats treated with suspensions of apoptotic PBMC (injected either intravenously or intramoycardially). Moreover, these hearts evidenced enhanced homing of macrophages and cells staining positive for c-kit, FLK-1, IGF-I and FGF-2 as compared to controls. A major finding in this study further was that the ratio of elastic and collagenous fibres within the scar tissue was altered in a favourable fashion in rats injected with apoptotic cells. Intravenous or intramyocardial injection of apoptotic cell suspensions results in attenuation of myocardial remodelling after experimental AMI, preserves left ventricular function, increases homing of regenerative cells and alters the composition of cardiac scar tissue. The higher expression of elastic fibres provides passive energy to the cardiac scar tissue and results in prevention of ventricular remodelling.

EGFR, BRAF and KRAS status in patients undergoing pulmonary metastasectomy from primary colorectal carcinoma: a prospective follow-up study

BACKGROUND

Pulmonary metastasectomy is an integral part of the interdisciplinary treatment of patients with pulmonary metastases (PMs) from colorectal carcinoma (CRC). Although alterations in the epidermal growth factor receptor (EGFR) pathway are common in CRC, there is still insufficient data regarding PM. We hypothesized that EGFR expression and Kirsten rat sarcoma viral oncogene homolog (KRAS)/BRAF mutations (Mts) might be associated with clinicopathological variables and the outcome in patients undergoing pulmonary metastasectomy.

METHODS

In this single-center study, 44 patients undergoing pulmonary metastasectomy from primary CRC were included and prospectively followed up. Tissue specimens of resected PMs were assessed. Restriction fragment length analysis was used for BRAF V600E and KRAS codons 12 and 13 Mt analyses. EGFR expression was evaluated by immunohistochemistry. Patients were followed up in 3-6-month intervals.

RESULTS

EGFR expression was evident in 49 % of the PMs, whereas Mts in KRAS and BRAF were detected in 48 and 0 %, respectively. Time to lung-specific recurrence after metastasectomy was significantly decreased in patients with KRAS mutated PMs in univariate (p = 0.013) and multivariate analysis (p = 0.035), whereas EGFR expression had no impact on recurrence free survival. Moreover, KRAS Mts were associated with the number of PMs (p = 0.037) and with the lung as first site of recurrence after metastasectomy (p = 0.047).

DISCUSSION

This is the first evaluation of EGFR pathway alterations in the setting of pulmonary metastasectomy. Our data suggest that patients with KRAS Mts are at high risk for early pulmonary recurrence and have a more diffuse pattern of metastasis. These findings may have impact on the therapeutic management of CRC patients with pulmonary spreading.

Aberrant T cell activation and heightened apoptotic turnover in end-stage renal failure patients: a comparative evaluation between non-dialysis, haemodialysis, and peritoneal dialysis

Patients in end-stage renal disease (ESRD) have a high incidence of bacterial and viral infections. Fifteen non-dialysed (ND), 15 haemodialysed (HD), 15 patients with peritoneal dialysis (PD), and 15 healthy controls were included. T cell proliferation was measured by [3H]thymidine uptake. Apoptosis and cell phenotype were determined by FACS. sTNF-R1, sCD95, interleukin-1beta-converting enzyme (sICE), and interleukin (IL)-10 were measured by ELISA. PHA and CD3-driven T cell proliferation were significantly decreased in ESRD patients. CD3(+), CD19(+) B cells, and percentage of CD4(+) T cells were significantly reduced. Percent memory T cells (CD45RO(+)) and cells undergoing apoptosis (CD95(+)/Annexin V+) were significantly increased in ESRF. Moreover, sCD95, sTNFRI, and ICE were significantly increased. Serum level of IL-10, a Th2 cytokine, was enhanced. These findings strongly suggest that in ESRD patients Th1 T cells are selectively susceptible to undergo apoptosis. This observation provides an additional pathophysiological concept in the genesis of Th2 dominance.

Discrimination of clinical stages in non-small cell lung cancer patients by serum HSP27 and HSP70: a multi-institutional case-control study

INTRODUCTION

Lung cancer represents a major healthcare problem. Accordingly, there is an urgent need to identify serum biomarkers for early diagnosis of lung pathology. We have recently described that patients with manifest COPD evidence elevated levels of heat shock proteins (HSPs). Based on these data, we speculated whether HSPs are also increased in patients with diagnosed lung cancer.

METHODS

Serum levels of HSP27, phospho-HSP27 (pHSP27) and HSP70 in patients with non-small cell lung cancer (NSCLC) diagnosed at an early (stages I-II, n=37) or advanced (stages IIIA-IV, n=72) stage were determined by using ELISA. Healthy smokers (n=24), healthy never-smoker volunteers (n=33) and COPD patients (n=34) according to GOLD classification served as control population.

RESULTS

Serum levels of HSP27 were elevated in patients with NSCLC diagnosed at an early or advanced stage when compared with both healthy control groups (P<0.005 and P<0.0001 respectively). Statistically significant differences were furthermore found between the groups of patients with early vs. advanced stage NSCLC (P=0.0021). Serum levels of HSP70 were also significantly elevated in patients with NSCLC diagnosed at an early or at an advanced stage when compared with either healthy control groups (P=0.0028 and P<0.0001 respectively). In univariate logistic regression models including healthy subjects and patients with NSCLC, HSP70 had an area under the curve (AUC) of 0.779 (P<0.0001) and HSP27 showed an AUC of 0.870 (P<0.0001).

CONCLUSION

Our data suggest that serum HSP27 levels might serve as a possible tool to discriminate between early and advanced stages NSCLC.

Up-regulation of interleukin 33 and soluble ST2 serum levels in liver failure

BACKGROUND

IL-33, a member of the IL-1 family, induces the production of pro-inflammatory and Th2-associated cytokines and may also serve as an 'alarmin' similar to HMGB1. Soluble ST2 has been implicated as a decoy receptor, to attenuate Th2 inflammatory responses. The relevance of both molecules in hepatic failure is unknown.

MATERIALS AND METHODS

The trial was a prospective preliminary study in a university hospital surgical ICU; 11 patients with acute liver failure (ALF) and 12 patients with acute-on-chronic liver failure (ACLF), who were admitted to the ICU; 14 patients with chronic hepatic failure (CHF) awaiting liver transplantation; 13 healthy individuals served as controls. IL-33 and soluble ST2 concentrations were determined by enzyme linked immunosorbent assay (ELISA).

RESULTS

The concentration of IL-33 and soluble ST2 was significantly higher in ALF, ACLF, and CHF patients compared with the controls. Soluble ST2 serum concentration was significantly elevated in ALF and ACLF compared with CHF; moreover, soluble ST2 was significantly higher in CHF compared with healthy controls. IL-33 and soluble ST2 serum levels correlated significantly (r = 0.6117, P < 0.0001). Moreover, there was a correlation between IL-33 serum levels and alanine aminotransferase (ALT) activity in CHF, ALF, and ACLF patients (r = 0.4321, P = 0.0171).

CONCLUSION

Our data provide evidence for elevated levels of IL-33 and soluble ST2 in liver failure, which could a sign of immune hyperactivation, and/or a mechanism to down-regulate inflammation. Especially, soluble ST2 maybe useful to discern acute from chronic hepatic failure or to monitor the course and the severity of the disease.

The serine proteases dipeptidyl-peptidase 4 and urokinase are key molecules in human and mouse scar formation

Despite recent advances in understanding skin scarring, mechanisms triggering hypertrophic scar formation are still poorly understood. In the present study, we investigate mature human hypertrophic scars and developing scars in mice at single cell resolution. Compared to normal skin, we find significant differences in gene expression in most cell types present in scar tissue. Fibroblasts show the most prominent alterations in gene expression, displaying a distinct fibrotic signature. By comparing genes upregulated in murine fibroblasts during scar development with genes highly expressed in mature human hypertrophic scars, we identify a group of serine proteases, tentatively involved in scar formation. Two of them, dipeptidyl-peptidase 4 (DPP4) and urokinase (PLAU), are further analyzed in functional assays, revealing a role in TGFβ1-mediated myofibroblast differentiation and over-production of components of the extracellular matrix in vitro. Topical treatment with inhibitors of DPP4 and PLAU during scar formation in vivo shows anti-fibrotic activity and improvement of scar quality, most prominently after application of the PLAU inhibitor BC-11. In this study, we delineate the genetic landscape of hypertrophic scars and present insights into mechanisms involved in hypertrophic scar formation. Our data suggest the use of serine protease inhibitors for the treatment of skin fibrosis.

Mononuclear cell secretome protects from experimental autoimmune myocarditis

AIMS

Supernatants of serum-free cultured mononuclear cells (MNC) contain a mix of immunomodulating factors (secretome), which have been shown to attenuate detrimental inflammatory responses following myocardial ischaemia. Inflammatory dilated cardiomyopathy (iDCM) is a common cause of heart failure in young patients. Experimental autoimmune myocarditis (EAM) is a CD4+ T cell-dependent model, which mirrors important pathogenic aspects of iDCM. The aim of this study was to determine the influence of MNC secretome on myocardial inflammation in the EAM model.

METHODS AND RESULTS

BALB/c mice were immunized twice with an alpha myosin heavy chain peptide together with Complete Freund adjuvant. Supernatants from mouse mononuclear cells were collected, dialysed, and injected i.p. at Day 0, Day 7, or Day 14, respectively. Myocarditis severity, T cell responses, and autoantibody formation were assessed at Day 21. The impact of MNC secretome on CD4+ T cell function and viability was evaluated using in vitro proliferation and cell viability assays. A single high-dose application of MNC secretome, injected at Day 14 after the first immunization, effectively attenuated myocardial inflammation. Mechanistically, MNC secretome induced caspase-8-dependent apoptosis in autoreactive CD4+ T cells.

CONCLUSION

MNC secretome abrogated myocardial inflammation in a CD4+ T cell-dependent animal model of autoimmune myocarditis. This anti-inflammatory effect of MNC secretome suggests a novel and simple potential treatment concept for inflammatory heart diseases.

The secretome of apoptotic human peripheral blood mononuclear cells attenuates secondary damage following spinal cord injury in rats

After spinal cord injury (SCI), secondary damage caused by oxidative stress, inflammation, and ischemia leads to neurological deterioration. In recent years, therapeutic approaches to trauma have focused on modulating this secondary cascade. There is increasing evidence that the success of cell-based SCI therapy is due mainly to secreted factors rather than to cell implantation per se. This study investigated peripheral blood mononuclear cells as a source of factors for secretome- (MNC-secretome-) based therapy. Specifically, we investigated whether MNC-secretome had therapeutic effects in a rat SCI contusion model and its possible underlying mechanisms. Rats treated with MNC-secretome showed substantially improved functional recovery, attenuated cavity formation, and reduced acute axonal injury compared to control animals. Histological evaluation revealed higher vascular density in the spinal cords of treated animals. Immunohistochemistry showed that MNC-secretome treatment increased the recruitment of CD68(+) cells with concomitant reduction of oxidative stress as reflected by lower expression of inducible nitric oxide synthase. Notably, MNC-secretome showed angiogenic properties ex vivo in aortic rings and spinal cord tissue, and experiments showed that the angiogenic potential of MNC-secretome may be regulated by CXCL-1 upregulation in vivo. Moreover, systemic application of MNC-secretome activated the ERK1/2 pathway in the spinal cord. Taken together, these results indicate that factors in MNC-secretome can mitigate the pathophysiological processes of secondary damage after SCI and improve functional outcomes in rats.

High VEGFR-3-positive circulating lymphatic/vascular endothelial progenitor cell level is associated with poor prognosis in human small cell lung cancer

PURPOSE

The newly identified bone marrow-derived cell population, called lymphatic/vascular endothelial progenitor cells (LVEPC), has been shown to contribute to lymph capillary growth in experimental tumor systems. The clinical significance of these cells has not yet been investigated in a human malignancy. Our aim was to study whether peripheral blood circulating LVEPCs participate in the progression of human small cell lung cancer (SCLC).

EXPERIMENTAL DESIGN

A total of 88 patients with limited-stage SCLC and 32 tumor-free control subjects were included. Peripheral blood circulating LVEPC labeled with CD34 and vascular endothelial growth factor receptor-3 (VEGFR3) antibodies and the serum levels of the key lymphangiogenic molecule VEGF-C were measured by flow cytometry and ELISA, respectively.

RESULTS

CD34-positive/VEGFR3-positive LVEPC levels were significantly increased in patients (versus controls; P<0.01), and there was also a significant relationship between LVEPC counts and lymph node metastasis (P<0.01). High pretreatment circulating LVEPC numbers correlated with poor overall survival (P<0.01). Although we observed significantly elevated VEGF-C concentrations in patients (versus controls; P<0.01), there was no significant correlation between VEGF-C and LVEPC levels. Moreover, no significant differences in peripheral blood VEGF-C levels were seen between patients subgrouped by clinicopathologic variables including tumor and lymph node stages and survival.

CONCLUSIONS

Peripheral blood levels of bone marrow-derived LVEPCs are significantly increased in patients with SCLC and correlate with lymphatic involvement and prognosis. This is the first study that shows evidence of increased numbers of circulating LVEPC in patients with a malignant tumor.

Quantitative changes in T-cell populations after left ventricular assist device implantation: relationship to T-cell apoptosis and soluble CD95

BACKGROUND

Left ventricular assist devices (LVADs) are currently being evaluated as permanent therapy for end-stage heart failure. Because life-threatening infections limit successful long-term device implantation, we investigated the relationship between quantitative T-cell defects in LVAD recipients and CD95-mediated T-cell apoptosis.

METHODS AND RESULTS

Immunological studies were performed in NYHA class IV patients awaiting cardiac transplantation who received either a TCI Heartmate left ventricular assist device (LVAD) or medical management. Fluorochrome-labeled Mabs were used in T-cell phenotypic analyses. T-cell apoptosis was measured by annexin V binding of T cells cultured in medium for 24 hours. Circulating serum levels of soluble CD95 were measured by ELISA. LVAD recipients had a relative lymphopenia and reduction in CD4 T-cell levels compared with NYHA class IV heart failure controls. These observations were confirmed in a longitudinal study in LVAD recipients, which showed that device implantation was accompanied by progressive and sustained reductions in circulating CD4 T-cell levels. These abnormalities in LVAD recipients were accompanied by increased levels of circulating soluble CD95 and by excessive CD4 and CD8 T-cell apoptosis. Susceptibility to induction of apoptosis was >2-fold greater for CD4 T cells than for CD8 T cells.

CONCLUSIONS

These results suggest that the reduction in CD4 T-cell levels accompanying LVAD implantation is a consequence of an augmented pathway of CD95-mediated apoptosis. The clinical consequences of these abnormalities may include increased prevalence of systemic infections.

Secretomes of apoptotic mononuclear cells ameliorate neurological damage in rats with focal ischemia

The pursuit of targeting multiple pathways in the ischemic cascade of cerebral stroke is a promising treatment option. We examined the regenerative potential of conditioned medium derived from rat and human apoptotic mononuclear cells (MNC), rMNC ^apo sec and hMNC ^apo sec, in experimental stroke.

We performed middle cerebral artery occlusion on Wistar rats and administered apoptotic MNC-secretomes intraperitoneally in two experimental settings. Ischemic lesion volumes were determined 48 hours after cerebral ischemia. Neurological evaluations were performed after 6, 24 and 48 hours. Immunoblots were conducted to analyze neuroprotective signal-transduction in human primary glia cells and neurons. Neuronal sprouting assays were performed and neurotrophic factors in both hMNC ^apo sec and rat plasma were quantified using ELISA.

Administration of rat as well as human apoptotic MNC-secretomes significantly reduced ischemic lesion volumes by 36% and 37%, respectively. Neurological examinations revealed improvement after stroke in both treatment groups. Co-incubation of human astrocytes, Schwann cells and neurons with hMNC ^apo sec resulted in activation of several signaling cascades associated with the regulation of cytoprotective gene products and enhanced neuronal sprouting in vitro. Analysis of neurotrophic factors in hMNC ^apo sec and rat plasma revealed high levels of brain derived neurotrophic factor (BDNF).

Our data indicate that apoptotic MNC-secretomes elicit neuroprotective effects on rats that have undergone ischemic stroke.

Patients with severe aortic valve stenosis and impaired platelet function benefit from preoperative desmopressin infusion

BACKGROUND

Patients with severe aortic valve stenosis have a markedly reduced platelet function as measured by a prolonged collagen adenosine diphosphate closure time (CADP-CT) determined by the platelet function analyzer PFA-100. We hypothesized that such patients may benefit from desmopressin when they present with prolonged CADP-CT due to the specific action of desmopressin on von Willebrand factor (VWF) and CADP-CT.

METHODS

In this double-blind, randomized placebo controlled trial, 43 patients undergoing aortic valve replacement (due to severe aortic valve stenosis with CADP-CT>170 seconds) were given desmopressin 0.3 μg/kg or saline intravenously after induction of anesthesia. Measurement of CADP-CT, factor VIII activity, von Willebrand factor antigen, GpIb binding activity, ristocetin cofactor activity, collagen-binding activity, and multimers were performed after induction of anesthesia, one hour after desmopressin infusion, and 24 hours postoperatively.

RESULTS

In the majority of patients, baseline values of von Willebrand factor related indices were normal, but increased one hour after infusion of desmopressin by 73% to 90% as compared with placebo. Selective loss of high molecular weight multimers was seen only in a minority of patients. The CADP-CT was greater than 170 seconds in 92% of screened patients, and desmopressin shortened CADP-CT by 48% versus baseline and reduced postoperative blood loss by 42% (p<0.001).

CONCLUSIONS

Prolonged CADP-CT indicates platelet dysfunction in severe aortic valve stenosis, and can guide the use of desmopressin as an effective prohemostatic agent in patients with severe aortic valve stenosis.

Reproducibility of GMP-compliant production of therapeutic stressed peripheral blood mononuclear cell-derived secretomes, a novel class of biological medicinal products

BACKGROUND

The recent concept of secretome-based tissue regeneration has profoundly altered the field of regenerative medicine and offers promising novel therapeutic options. In contrast to medicinal products with a single active substance, cell-derived secretomes comprise pleiotropic bioactive ingredients, representing a major obstacle for reproducible drug product efficacy and warranting patient safety. Good manufacturing practice (GMP)-compliant production guarantees high batch-to-batch consistency and reproducible efficacy of biological medicinal products, but different batches of cellular secretomes produced under GMP have not been compared yet, and suitable quality control parameters have not been established. To this end, we analyzed diverse biological and functional parameters of different batches produced under GMP of the secretome obtained from γ-irradiated peripheral blood mononuclear cells with proven tissue regenerative properties in infarcted myocardium, stroke, spinal cord injury, and skin wounds.

METHODS

We quantified key secretome ingredients, including cytokines, lipids, and extracellular vesicles, and functionally assessed potency in tube formation assay, ex vivo aortic ring sprouting assay, and cell-based protein and reporter gene assays. Furthermore, we determined secretome stability in different batches after 6 months of storage at various ambient temperatures.

RESULTS

We observed that inter-batch differences in the bioactive components and secretome properties were small despite considerable differences in protein concentrations and potencies between individual donor secretomes. Stability tests showed that the analytical and functional properties of the secretomes remained stable when lyophilisates were stored at temperatures up to + 5 °C for 6 months.

CONCLUSIONS

We are the first to demonstrate the consistent production of cell-derived, yet cell-free secretome as a biological medicinal product. The results from this study provide the basis for selecting appropriate quality control parameters for GMP-compliant production of therapeutic cell secretomes and pave the way for future clinical trials employing secretomes in tissue regenerative medicine.

Non-pulsatile blood flow is associated with enhanced cerebrovascular carbon dioxide reactivity and an attenuated relationship between cerebral blood flow and regional brain oxygenation

BACKGROUND

Systemic blood flow in patients on extracorporeal assist devices is frequently not or only minimally pulsatile. Loss of pulsatile brain perfusion, however, has been implicated in neurological complications. Furthermore, the adverse effects of absent pulsatility on the cerebral microcirculation are modulated similarly as CO₂ vasoreactivity in resistance vessels. During support with an extracorporeal assist device swings in arterial carbon dioxide partial pressures (PaCO₂) that determine cerebral oxygen delivery are not uncommon-especially when CO₂ is eliminated by the respirator as well as via the gas exchanger of an extracorporeal membrane oxygenation machine. We, therefore, investigated whether non-pulsatile flow affects cerebrovascular CO₂ reactivity (CVR) and regional brain oxygenation (rSO₂).

METHODS

In this prospective, single-centre case-control trial, we studied 32 patients undergoing elective cardiac surgery. Blood flow velocity in the middle cerebral artery (MCAv) as well as rSO₂ was determined during step changes of PaCO₂ between 30, 40, and 50 mmHg. Measurements were conducted on cardiopulmonary bypass during non-pulsatile and postoperatively under pulsatile blood flow at comparable test conditions. Corresponding changes of CVR and concomitant rSO₂ alterations were determined for each flow mode. Each patient served as her own control.

RESULTS

MCAv was generally lower during hypocapnia than during normocapnia and hypercapnia (p < 0.0001). However, the MCAv/PaCO₂ slope during non-pulsatile flow was 14.4 cm/s/mmHg [CI 11.8-16.9] and 10.4 cm/s/mmHg [CI 7.9-13.0] after return of pulsatility (p = 0.03). During hypocapnia, non-pulsatile CVR (4.3 ± 1.7%/mmHg) was higher than pulsatile CVR (3.1 ± 1.3%/mmHg, p = 0.01). Independent of the flow mode, we observed a decline in rSO2 during hypocapnia and a corresponding rise during hypercapnia (p < 0.0001). However, the relationship between ΔrSO₂ and ΔMCAv was less pronounced during non-pulsatile flow.

CONCLUSIONS

Non-pulsatile perfusion is associated with enhanced cerebrovascular CVR resulting in greater relative decreases of cerebral blood flow during hypocapnia. Heterogenic microvascular perfusion may account for the attenuated ΔrSO₂/ΔMCAv slope. Potential hazards related to this altered regulation of cerebral perfusion still need to be assessed.

TRIAL REGISTRATION

The study was retrospectively registered on October 30, 2018, with Clinical Trial.gov (NCT03732651).