Biology subjects

Giebel, B.

Publications and source records attributed to Giebel, B..

4 recordsLinked to original sources

bioRxiv2021

Acid sphingomyelinase deactivation post-ischemia/ reperfusion promotes cerebral angiogenesis and brain remodeling via small extracellular vesicles

Functional inhibitors of acid sphingomyelinase are clinically used as anti-depressants since [~]60 years. Here, we show that acid sphingomyelinase inhibition by the antidepressants amitriptyline, fluoxetine and desipramine protects from ischemia/reperfusion and elicits a profound brain remodeling response with increased angiogenesis, improved blood-brain barrier integrity, reduced brain leukocyte infiltration and increased neuronal survival. Angiogenesis is promoted by small extracellular vesicles with bona fide characteristics of exosomes, which are released from endothelial cells and which constitute an elegant target for the amplification of stroke recovery.

neuroscience↗

bioRxiv2020

Independent human mesenchymal stromal cell-derived extracellular vesicle preparations differentially affect symptoms in an advanced murine Graft-versus-Host-Disease model

Extracellular vesicles (EVs) harvested from cell culture supernatants of human mesenchymal stromal cells (MSCs) suppress acute inflammation in preclinical models of various diseases. Furthermore, they promote regeneration of damaged tissues. Following successful clinical treatment of a steroid-refractory Graft-versus-Host-Disease (GvHD) patient with EVs prepared from conditioned media of human bone marrow (BM)-derived MSCs, we aim to improve MSC-EV production and quality control towards clinical application. Observing functional differences of independent MSC-EV preparations in vitro, we established an optimized murine GvHD model for the analysis of independent MSC-EV preparations in vivo. To this end, T cell depleted allogeneic BM cells co-transplanted with naive allogeneic spleen-derived T cells induced GvHD symptoms with reproducible strengths in mice being preconditioned by ionizing irradiation. Administration of MSC-EV preparations with confirmed in vitro immune modulatory properties at three consecutive days significantly suppressed GvHD symptoms. In contrast, application of MSC-EV preparations lacking these in vitro immune modulating capabilities failed to suppress GvHD symptoms. Thus, our results reveal therapeutic differences among independent MSC-EV preparations that had been produced in a standardized manner. Thus, given this functional heterogeneity, any individual MSC-EV preparation considered for the clinical application should be evaluated for its potency prior to administration to patients.

cell biology↗

bioRxiv2020

Cell-to-cell spread inhibiting antibodies constitute a correlate of protection against Herpes Simplex Virus Type 1 reactivations

Herpes simplex viruses (HSV) cause ubiquitous human infections. For vaccine development, knowledge concerning correlates of protection against HSV is essential. Therefore, we investigated if humans principally can produce highly protective cell-to-cell spread inhibiting antibodies upon natural infection and whether such antibody responses correlate with protection from HSV reactivation. We established a high-throughput HSV-1 GFP reporter virus-based assay and screened 2496 human plasma samples for HSV-1 cell-to-cell spread inhibiting antibodies. We conducted a survey among the blood donors to analyze the correlation between the presence of cell-to-cell spread inhibiting antibodies in plasma and the frequency of HSV reactivations. In total, 128 of 2496 blood donors (5.1 %) exhibited high levels of HSV-1 cell-to-cell spread inhibiting antibodies in the plasma. Such individuals showed a significantly lower frequency of HSV reactivations compared to subjects without sufficient levels of HSV-1 cell-to-cell spread inhibiting antibodies. This study provides two important findings: (I) a fraction of humans produce HSV cell-to-cell spread inhibiting antibodies upon natural infection and (II) such antibodies correlate with protection against recurrent HSV. Moreover, these elite neutralizers can provide promising material for hyperimmunoglobulin, the isolation of superior antiviral antibodies and information for the design of a vaccine against HSV. ImportanceHerpes simplex virus 1 infections can cause painful mucosal lesions at the oral or genital tract and severe, life threatening disease in immunosuppressed patients or neonates. There is no approved vaccine available, and the emergence of drug resistances especially in long time treated patients makes the treatment increasingly difficult. We tested 2496 people for HSV-1 cell-to-cell spread inhibiting antibodies. Five percent exhibited functional titers such antibodies and showed significantly lower risk of reactivations, uncovering cell-to-cell spread inhibiting antibodies as a correlate of protection against Herpes simplex virus reactivations. Isolation of the cell-to-cell spread inhibiting antibodies from B-cells of these donors may contribute to develop novel antibody-based interventions for prophylactic and therapeutic use and provide starting material for vaccine development.

immunology↗

bioRxiv2020

Human neonatal B cell immunity differs from the adult version by conserved Ig repertoires and rapid, but transient response dynamics

The human infant B cell system is considered premature or impaired. Here we show that most cord blood B cells are mature and functional as seen in adults, albeit with distinct transcriptional programs providing accelerated responsiveness to T cell-independent and T cell-dependent stimulation and facilitated IgA class switching. Stimulation drives extensive differentiation into antibody-secreting cells, thereby presumably limiting memory B cell formation. The neonatal Ig-repertoire is highly variable, but conserved, showing recurrent B cell receptor (BCR) clonotypes frequently shared between neonates. Our study demonstrates that cord blood B cells are not impaired but differ from their adult counterpart in a conserved BCR repertoire and rapid but transient response dynamics. These properties may account for the sensitivity of neonates to infections and limited effectivity of vaccination strategies. Humanized mice suggest that the distinctness of cord blood versus adult B cells is already reflected by the developmental program of hematopoietic precursors, arguing for a layered B-1/B-2 lineage system as in mice. Still, our findings reveal overall limited comparability of human cord blood B cells and murine B-1 cells. Significance StatementNeonates and infants suffer from enhanced susceptibility to infections. Our study contrasts with the current concept of a premature or impaired B cell system in neonates, by showing that most cord blood B cells are mature and functional. However, their responses are rapid but provide only short-term protection, which may help to improve infant vaccination strategies. We propose an altered perspective on the early human B cell system, which looks similar to but functions differently from the adult counterpart. Finally, our analysis indicates that cord blood- and adult B cell development occur layered as in mice, but certain mouse models still may offer a limited view on human neonatal B cell immunity.

immunology↗