Regulatorische T-Zellen als neues Therapiekonzept in der Transplantationsmedizin

Die Transplantation von soliden Organen oder hämatopoetischen Stammzellen hat sich über die letzten Jahrzehnte für viele Patienten zu einer kurativen Therapieoption entwickelt. Der langfristige Transplantationserfolg ist jedoch wesentlich von der Kontrolle chronischer Abstoßungsreaktionen abhängig. Die Behandlungserfolge im Falle einer chronischen Abstoßungsreaktion sind trotz des Einsatzes moderner immunsuppressiver Medikamente bis heute leider nicht zufriedenstellend. Der therapeutische Einsatz von regulatorischen T-Zellen, welche anti-inflammatorisch wirken und die Immunhomöostase erhalten oder nach Inflammationsprozessen wiederherstellen, entwickelte sich in den letzten Jahren zu einem vielversprechenden Therapiekonzept. Hierbei werden regulatorische T-Zellen (Tregs) dem Patienten selbst oder dem ursprünglichen Stammzellspender entnommen, angereichert und anschließen intravenös verabreicht. Trotz der technischen Möglichkeiten und der klinischen Erfahrungen, die sowohl die Sicherheit als auch die Wirksamkeit von Tregs belegen, stagnieren die Entwicklungen in frühen Phasen klinischer Studien. Im Rahmen unserer Arbeiten haben wir in den letzten Jahren ein eigenes Protokoll entwickelt, das es uns ermöglicht, mittels ex-vivo-Expansion von Tregs aus 50 ml peripherem Vollblut – ohne die Notwendigkeit einer Leukozytapherese – ein sehr reines und funktionell wirksames Treg-Produkt zu generieren und dafür die Herstellungserlaubnis zu erlangen. Wir untersuchten zudem den Einfluss von konventionellen immunsuppressiven Medikamenten auf adoptiv transferierte Tregs, um Synergien zu nutzen und antagonistische Effekte zu vermeiden. Hierbei zeigte sich, dass Calcineurin-Inhibitoren wie Cyclosporin A und Mycophenolat Mofetil das Überleben und die Funktion adoptiv transferierter Tregs unterstützen, während Glukokortikoide in hoher Dosierung vermieden werden sollten. Mit diesem Wissen gelang uns die Translation ex vivo expandierter Tregs: im Rahmen einer Phase I/IIa-Studie konnten bereits Patienten, die eine Lebendspende-Nierentransplantation erhalten haben erfolgreich behandelt werden. Zusätzlich behandelten wir erstmalig drei Kinder, die nach allogener Stammzelltransplantation eine schwere, therapie-refraktäre chronische Abstoßungsreaktion erlitten hatten. Bei allen drei Patienten zeigte sich eine deutliche Besserung des klinischen Bildes und wir konnten zudem ein immunologisches Engraftment von naiven T-Zellen, naiven B-Zellen und dendritischen Zellen nachweisen. Angesichts dieser Ergebnisse und der übereinstimmend vielversprechenden Erfahrungen anderer Gruppen weltweit bleibt es unsere gemeinsame Aufgabe, die Sicherheit und Wirksamkeit von Treg-Therapien zeitnah im Rahmen größerer klinischer Studien weiter untersuchen. Gleichzeitig ist es essentiell, neue Erkenntnisse und innovative technische Möglichkeiten der Produktmodifikation fortlaufend in die Weiterentwicklung von Treg-Produkten einfließen zu lassen. Damit ist die Treg-Therapie auf absehbare Zeit zwar noch immer Einzelfällen vorbehalten, aber weitere wesentliche Meilensteine auf dem Weg in die breite klinische Anwendung werden nach und nach erreicht werden

Comprehensive Characterization of a Next-Generation Antiviral T-Cell Product and Feasibility for Application in Immunosuppressed Transplant Patients

Viral infections have a major impact on morbidity and mortality of immunosuppressed solid organ transplant (SOT) patients because of missing or failure of adequate pharmacologic antiviral treatment. Adoptive antiviral T-cell therapy (AVTT), regenerating disturbed endogenous T-cell immunity, emerged as an attractive alternative approach to combat severe viral complications in immunocompromised patients. AVTT is successful in patients after hematopoietic stem cell transplantation where T-cell products (TCPs) are manufactured from healthy donors. In contrast, in the SOT setting TCPs are derived from/applied back to immunosuppressed patients.We and others demonstrated feasibility of TCP generation from SOT patients and first clinical proof-of-concept trials revealing promising data. However, the initial efficacy is frequently lost longterm, because of limited survival of transferred short-lived T-cells indicating a need for next-generation TCPs. Our recent data suggest that Rapamycin treatment during TCP manufacture, conferring partial inhibition of mTOR, might improve its composition. The aim of this study was to confirm these promising observations in a setting closer to clinical challenges and to deeply characterize the next-generation TCPs. Using cytomegalovirus (CMV) as model, our next-generation Rapamycin-treated (Rapa-)TCP showed consistently increased proportions of CD4+ T-cells as well as CD4+ and CD8+ central-memory T-cells (TCM). In addition, Rapamycin sustained T-cell function despite withdrawal of Rapamycin, showed superior T-cell viability and resistance to apoptosis, stable metabolism upon activation, preferential expansion of TCM, partial conversion of other memory T-cell subsets to TCM and increased clonal diversity. On transcriptome level, we observed a gene expression profile denoting long-lived early memory T-cells with potent effector functions. Furthermore, we successfully applied the novel protocol for the generation of Rapa-TCPs to 19/19 SOT patients in a comparative study, irrespective Amini et al. Advanced CMV-Specific T-Cell Therapy for SOT of their history of CMV reactivation. Moreover, comparison of paired TCPs generated before/after transplantation did not reveal inferiority of the latter despite exposition to maintenance immunosuppression post-SOT. Our data imply that the Rapa-TCPs, exhibiting longevity and sustained T-cell memory, are a reasonable treatment option for SOT patients. Based on our success to manufacture Rapa-TCPs from SOT patients under maintenance immunosuppression, now, we seek ultimate clinical proof of efficacy in a clinical study

Neonatal innate immunity and Toll-like receptor

The innate immune response is the first line of defense against microbial infections. Innate immunity is made up of the surface barrier, cellular immunity and humoral immunity. In newborn, immunologic function and demands are different to adults. Neonatal innate immunity specifically suppresses Th1-type immune responses, and not Th2-type immune responses, which are enhanced. And the impaired response of macrophages is associated with the defective innate immunity in newborn period. Toll-like receptors (TLRs) play a key roles in the detection of invading pathogens and in the induction of innate immune responses. In newborn, the expression of TLRs is age dependent, so preterm has low expression of TLRs. Also, there are defects in signaling pathways downstream of TLRs. As a consequence, the defects of TLRs activity cause the susceptibility to infection in the neonatal period

Phagocytic ability of neutrophils and monocytes in neonates

<p>Abstract</p> <p>Background</p> <p>Infections by a variety of pathogens are a significant cause of morbidity and mortality during perinatal period. The susceptibility of neonates to bacterial infections has been attributed to immaturity of innate immunity. It is considered that one of the impaired mechanisms is the phagocytic function of neutrophils and monocytes. The purpose of the present study was to investigate the phagocytic ability of neonates at birth.</p> <p>Methods</p> <p>The phagocytic ability of neutrophils and monocytes of 42 neonates was determined using the Phagotest flow cytometry method, that assesses the intake of <it>E. Coli </it>by phagocytes, in cord blood and in peripheral blood 3 days after birth. Fifteen healthy adults were included in the study as controls.</p> <p>Results</p> <p>The phagocytic ability of neutrophils in the cord blood of neonates was significantly reduced compared to adults. The 3^rdpostnatal day the reduction of phagocytic ability of neutrophils was no longer significant compared to adults. The phagocytic ability of monocytes did not show any difference from that of adults either at birth or the 3^rdpostnatal day.</p> <p>Conclusions</p> <p>Our findings indicate that the intake of <it>E. Coli </it>by phagocytes is impaired at birth in both preterm and full term neonates compared to adults. This defect is transient, with the phagocytic ability in neonates reaching that of the adults 3 days after birth.</p

Lactobacillus pentosus strain b240 suppresses pneumonia induced by Streptococcus pneumoniae in mice.

Oral administration of probiotics has been known to improve inflammatory responses against infectious diseases. Here, we describe the inhibitory effect of oral intake of heat-killed Lactobacillus pentosus strain b240 (b240) on pneumococcal pneumonia in a murine experimental model

Genome-wide mapping of cystitis due to Streptococcus agalactiae and Escherichia coli in mice identifies a unique bladder transcriptome that signifies pathogen-specific antimicrobial defense against urinary tract infection

The most common causes of urinary tract infections (UTIs) are Gram-negative pathogens such as Escherichia coli; however, Gram-positive organisms, including Streptococcus agalactiae, or group B streptococcus (GBS), also cause UTI. In GBS infection, UTI progresses to cystitis once the bacteria colonize the bladder, but the host responses triggered in the bladder immediately following infection are largely unknown. Here, we used genome-wide expression profiling to map the bladder transcriptome of GBS UTI in mice infected transurethrally with uropathogenic GBS that was cultured from a 35-year-old women with cystitis. RNA from bladders was applied to Affymetrix Gene-1.0ST microarrays; quantitative reverse transcriptase PCR (qRT-PCR) was used to analyze selected gene responses identified in array data sets. A surprisingly small significant-gene list of 172 genes was identified at 24 h; this compared to 2,507 genes identified in a side-by-side comparison with uropathogenic E. coli (UPEC). No genes exhibited significantly altered expression at 2 h in GBS-infected mice according to arrays despite high bladder bacterial loads at this early time point. The absence of a marked early host response to GBS juxtaposed with broad-based bladder responses activated by UPEC at 2 h. Bioinformatics analyses, including integrative system-level network mapping, revealed multiple activated biological pathways in the GBS bladder transcriptome that regulate leukocyte activation, inflammation, apoptosis, and cytokine-chemokine biosynthesis. These findings define a novel, minimalistic type of bladder host response triggered by GBS UTI, which comprises collective antimicrobial pathways that differ dramatically from those activated by UPEC. Overall, this study emphasizes the unique nature of bladder immune activation mechanisms triggered by distinct uropathogens

Coxiella burnetii, the Agent of Q Fever, Replicates within Trophoblasts and Induces a Unique Transcriptional Response

Q fever is a zoonosis caused by Coxiella burnetii, an obligate intracellular bacterium typically found in myeloid cells. The infection is a source of severe obstetrical complications in humans and cattle and can undergo chronic evolution in a minority of pregnant women. Because C. burnetii is found in the placentas of aborted fetuses, we investigated the possibility that it could infect trophoblasts. Here, we show that C. burnetii infected and replicated in BeWo trophoblasts within phagolysosomes. Using pangenomic microarrays, we found that C. burnetii induced a specific transcriptomic program. This program was associated with the modulation of inflammatory responses that were shared with inflammatory agonists, such as TNF, and more specific responses involving genes related to pregnancy development, including EGR-1 and NDGR1. In addition, C. burnetii stimulated gene networks organized around the IL-6 and IL-13 pathways, which both modulate STAT3. Taken together, these results revealed that trophoblasts represent a protective niche for C. burnetii. The activation program induced by C. burnetii in trophoblasts may allow bacterial replication but seems unable to interfere with the development of normal pregnancy. Such pathophysiologocal processes should require the activation of immune placental cells associated with trophoblasts