Accumulation of tissue-resident natural killer cells, innate lymphoid cells, and CD8+ T cells towards the center of human lung tumors

Lung cancer is a leading cause of cancer-related death worldwide. Despite recent advances in tissue immunology, little is known about the spatial distribution of tissue-resident lymphocyte subsets in lung tumors. Using high-parameter flow cytometry, we identified an accumulation of tissue-resident lymphocytes including tissue-resident NK (trNK) cells and CD8+ tissue-resident memory T (TRM) cells toward the center of human non-small cell lung carcinomas (NSCLC). Chemokine receptor expression patterns indicated different modes of tumor-infiltration and/or residency between trNK cells and CD8+ TRM cells. In contrast to CD8+ TRM cells, trNK cells and ILCs generally expressed low levels of immune checkpoint receptors independent of location in the tumor. Additionally, granzyme expression in trNK cells and CD8+ TRM cells was highest in the tumor center, and intratumoral CD49a+CD16- NK cells were functional and responded stronger to target cell stimulation than their CD49a- counterparts, indicating functional relevance of trNK cells in lung tumors. In summary, the present spatial mapping of lymphocyte subsets in human NSCLC provides novel insights into the composition and functionality of tissue-resident immune cells, suggesting a role for trNK cells and CD8+ TRM cells in lung tumors and their potential relevance for future therapeutic approaches.

Comparison of Lung-Homing Receptor Expression and Activation Profiles on NK Cell and T Cell Subsets in COVID-19 and Influenza

Respiratory viral infections with SARS-CoV-2 and influenza viruses commonly induce a strong infiltration of immune cells into the human lung, with potential detrimental effects on the integrity of the lung tissue. Despite comprising the largest fractions of circulating lymphocytes in the lung, rather little is known about how peripheral blood natural killer (NK) cell and T cell subsets are equipped for lung-homing in COVID-19 and influenza. Here, we provide a detailed comparative analysis of NK cells and T cells in patients infected with SARS-CoV-2 or influenza virus, focusing on the protein and gene expression of chemokine receptors known to be involved in recruitment to the lung. For this, we used 28-colour flow cytometry as well as re-analysis of a publicly available single-cell RNA-seq dataset from bronchoalveolar lavage (BAL) fluid. Frequencies of NK cells and T cells expressing CXCR3, CXCR6, and CCR5 were altered in peripheral blood of COVID-19 and influenza patients, in line with increased transcript expression of CXCR3, CXCR6, and CCR5 and their respective ligands in BAL fluid. NK cells and T cells expressing lung-homing receptors displayed stronger phenotypic signs of activation compared to cells lacking lung-homing receptors, and activation was overall stronger in influenza compared to COVID-19. Together, our results indicate a role for CXCR3+, CXCR6+, and/or CCR5+ NK cells and T cells that potentially migrate to the lungs in moderate COVID-19 and influenza patients, identifying common targets for future therapeutic interventions in respiratory viral infections.

Autologous NK cells as consolidation therapy following stem cell transplantation in multiple myeloma

Few approaches have been made toward exploring autologous NK cells in settings of cancer immunotherapy. Here, we demonstrate the feasibility of infusing multiple doses of ex vivo activated and expanded autologous NK cells in patients with multiple myeloma (MM) post-autologous stem cell transplantation. Infused NK cells were detected in circulation up to 4 weeks after the last infusion. Elevations in plasma granzyme B levels were observed following each consecutive NK cell infusion. Moreover, increased granzyme B levels were detected in bone marrow 4 weeks after the last infusion. All measurable patients had objective, detectable responses after NK cell infusions in terms of reduction in M-component and/or minimal residual disease. The present study demonstrates that autologous NK cell-based immunotherapy is feasible in a setting of MM consolidation therapy. It opens up the possibility for usage of autologous NK cells in clinical settings where patients are not readily eligible for allogeneic NK cell-based immunotherapies.

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Infusing activated and expanded autologous NK cells in patients with MM is possible

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Infused NK cells are detected in circulation for up to 4 weeks

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Elevated granzyme B levels are observed following each consecutive NK cell infusion

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Objective, detectable responses after NK cell infusions are seen in patients

CD5 Surface Expression Marks Intravascular Human Innate Lymphoid Cells That Have a Distinct Ontogeny and Migrate to the Lung

Innate lymphoid cells (ILCs) contribute to immune defense, yet it is poorly understood how ILCs develop and are strategically positioned in the lung. This applies especially to human ILCs due to the difficulty of studying them in vivo. Here we investigated the ontogeny and migration of human ILCs in vivo with a humanized mouse model (“MISTRG”) expressing human cytokines. In addition to known tissue-resident ILC subsets, we discovered CD5-expressing ILCs that predominantly resided within the lung vasculature and in the circulation. CD5⁺ ILCs contained IFNγ-producing mature ILC1s as well as immature ILCs that produced ILC effector cytokines under polarizing conditions in vitro. CD5⁺ ILCs had a distinct ontogeny compared to conventional CD5^- ILCs because they first appeared in the thymus, spleen and liver rather than in the bone marrow after transplantation of MISTRG mice with human CD34⁺ hematopoietic stem and progenitor cells. Due to their strategic location, human CD5⁺ ILCs could serve as blood-borne sentinels, ready to be recruited into the lung to respond to environmental challenges. This work emphasizes the uniqueness of human CD5⁺ ILCs in terms of their anatomical localization and developmental origin compared to well-studied CD5^- ILCs.

Distinct developmental pathways from blood monocytes generate human lung macrophage diversity

The study of human macrophages and their ontogeny is an important unresolved issue. Here, we use a humanized mouse model expressing human cytokines to dissect the development of lung macrophages from human hematopoiesis in vivo. Human CD34⁺ hematopoietic stem and progenitor cells (HSPCs) generated three macrophage populations, occupying separate anatomical niches in the lung. Intravascular cell labeling, cell transplantation, and fate-mapping studies established that classical CD14⁺ blood monocytes derived from HSPCs migrated into lung tissue and gave rise to human interstitial and alveolar macrophages. In contrast, non-classical CD16⁺ blood monocytes preferentially generated macrophages resident in the lung vasculature (pulmonary intravascular macrophages). Finally, single-cell RNA sequencing defined intermediate differentiation stages in human lung macrophage development from blood monocytes. This study identifies distinct developmental pathways from circulating monocytes to lung macrophages and reveals how cellular origin contributes to human macrophage identity, diversity, and localization in vivo.

Natural killer cell immunotypes related to COVID-19 disease severity

Understanding innate immune responses in COVID-19 is important to decipher mechanisms of host responses and interpret disease pathogenesis. Natural killer (NK) cells are innate effector lymphocytes that respond to acute viral infections but might also contribute to immunopathology. Using 28-color flow cytometry, we here reveal strong NK cell activation across distinct subsets in peripheral blood of COVID-19 patients. This pattern was mirrored in scRNA-seq signatures of NK cells in bronchoalveolar lavage from COVID-19 patients. Unsupervised high-dimensional analysis of peripheral blood NK cells furthermore identified distinct NK cell immunotypes that were linked to disease severity. Hallmarks of these immunotypes were high expression of perforin, NKG2C, and Ksp37, reflecting increased presence of adaptive NK cells in circulation of patients with severe disease. Finally, arming of CD56bright NK cells was observed across COVID-19 disease states, driven by a defined protein-protein interaction network of inflammatory soluble factors. This study provides a detailed map of the NK cell activation landscape in COVID-19 disease.

Natural killer cell immunotypes related to COVID-19 disease severity

Understanding innate immune responses in COVID-19 is important to decipher mechanisms of host responses and interpret disease pathogenesis. Natural killer (NK) cells are innate effector lymphocytes that respond to acute viral infections but might also contribute to immunopathology. Using 28-color flow cytometry, we here reveal strong NK cell activation across distinct subsets in peripheral blood of COVID-19 patients. This pattern was mirrored in scRNA-seq signatures of NK cells in bronchoalveolar lavage from COVID-19 patients. Unsupervised high-dimensional analysis of peripheral blood NK cells furthermore identified distinct NK cell immunotypes that were linked to disease severity. Hallmarks of these immunotypes were high expression of perforin, NKG2C, and Ksp37, reflecting increased presence of adaptive NK cells in circulation of patients with severe disease. Finally, arming of CD56^bright NK cells was observed across COVID-19 disease states, driven by a defined protein-protein interaction network of inflammatory soluble factors. This study provides a detailed map of the NK cell activation landscape in COVID-19 disease.

NK cells are activated and primed for skin-homing during acute dengue virus infection in humans

Despite animal models showing that natural killer (NK) cells are important players in the early defense against many viral infections, the NK cell response is poorly understood in humans. Here we analyze the phenotype, temporal dynamics, regulation and trafficking of NK cells in a patient cohort with acute dengue virus infection. NK cells are robustly activated and proliferate during the first week after symptom debut. Increased IL-18 levels in plasma and in induced skin blisters of DENV-infected patients, as well as concomitant signaling downstream of the IL-18R, suggests an IL-18-dependent mechanism in driving the proliferative NK cell response. Responding NK cells have a less mature phenotype and a distinct chemokine-receptor imprint indicative of skin-homing. A corresponding NK cell subset can be localized to skin early during acute infection. These data provide evidence of an IL-18-driven NK cell proliferation and priming for skin-homing during an acute viral infection in humans.

Here, Zimmer et al. analyze the natural killer (NK) cell response in a patient cohort with acute dengue virus infection showing early NK cell activation and proliferation, and the data suggest that NK cell proliferation depends on IL-18 signaling, and that responding NK cells have a skin-homing phenotype.

Chronic hepatitis delta virus infection leads to functional impairment and severe loss of MAIT cells

BACKGROUND & AIMS

Hepatitis delta virus (HDV) infection is the most severe form of viral hepatitis. Although HDV-associated liver disease is considered immune-mediated, adaptive immune responses against HDV are weak. Thus, the role of several other cell-mediated mechanisms such as those driven by mucosa-associated invariant T (MAIT) cells, a group of innate-like T cells highly enriched in the human liver, has not been extensively studied in clinical HDV infection.

METHODS

MAIT cells from a sizeable cohort of patients with chronic HDV were analyzed ex vivo and in vitro after stimulation. Results were compared with MAIT cells from hepatitis B virus (HBV) monoinfected patients and healthy controls.

RESULTS

Circulating MAIT cells were dramatically decreased in the peripheral blood of HDV-infected patients. Signs of decline were also observed in the liver. In contrast, only a modest decrease of circulating MAIT cells was noted in HBV monoinfection. Unsupervised high-dimensional analysis of residual circulating MAIT cells in chronic HDV infection revealed the appearance of a compound phenotype of CD38^hiPD-1^hiCD28^loCD127^loPLZF^loEomes^loHelios^lo cells indicative of activation. Corroborating these results, MAIT cells exhibited a functionally impaired responsiveness. In parallel to MAIT cell loss, HDV-infected patients exhibited signs of monocyte activation and increased levels of proinflammatory cytokines IL-12 and IL-18. In vitro, IL-12 and IL-18 induced an activated MAIT cell phenotype similar to the one observed ex vivo in HDV-infected patients. These cytokines also promoted MAIT cell death, suggesting that they may contribute to MAIT cell activation and subsequent loss during HDV infection.

CONCLUSIONS

These results suggest that chronic HDV infection engages the MAIT cell compartment causing activation, functional impairment, and subsequent progressive loss of MAIT cells as the HDV-associated liver disease progresses.

LAY SUMMARY

Hepatitis delta virus (HDV) infection is the most severe form of viral hepatitis. We found that in patients with HDV, a subset of innate-like T cells called mucosa-associated invariant T cells (or MAIT cells), which are normally abundant in peripheral blood and the liver, are activated, functionally impaired and severely depleted.

Influenza A Virus Infection Induces Hyperresponsiveness in Human Lung Tissue-Resident and Peripheral Blood NK Cells

NK cells in the human lung respond to influenza A virus- (IAV-) infected target cells. However, the detailed functional capacity of human lung and peripheral blood NK cells remains to be determined in IAV and other respiratory viral infections. Here, we investigated the effects of IAV infection on human lung and peripheral blood NK cells in vitro and ex vivo following clinical infection. IAV infection of lung- and peripheral blood-derived mononuclear cells in vitro induced NK cell hyperresponsiveness to K562 target cells, including increased degranulation and cytokine production particularly in the CD56^brightCD16^- subset of NK cells. Furthermore, lung CD16^- NK cells showed increased IAV-mediated but target cell-independent activation compared to CD16⁺ lung NK cells or total NK cells in peripheral blood. IAV infection rendered peripheral blood NK cells responsive toward the normally NK cell-resistant lung epithelial cell line A549, indicating that NK cell activation during IAV infection could contribute to killing of surrounding non-infected epithelial cells. In vivo, peripheral blood CD56^dimCD16⁺ and CD56^brightCD16^- NK cells were primed during acute IAV infection, and a small subset of CD16^-CD49a⁺CXCR3⁺ NK cells could be identified, with CD49a and CXCR3 potentially promoting homing to and tissue-retention in the lung during acute infection. Together, we show that IAV respiratory viral infections prime otherwise hyporesponsive lung NK cells, indicating that both CD16⁺ and CD16^- NK cells including CD16^-CD49a⁺ tissue-resident NK cells could contribute to host immunity but possibly also tissue damage in clinical IAV infection.

Impact of Telemedicine Tools on Record Keeping and Compliance in Haemophilia Care

Background Record keeping is integral to home treatment for haemophilia. Issues with paper diaries include questionable compliance, data validity and quality. Implementation of electronic diaries (e-diaries) in haemophilia patients could improve documentation of home treatment.

Aim This article evaluates the effects of an e-diary, Haemoassist, on recording and patient compliance with therapy.

Patients and Methods An explorative study was used to assess the sequential use of paper diaries and e-diaries by 99 patients with severe haemophilia A or B and 1 with severe factor VII deficiency. Median age was 41 years. Information was obtained from paper records for 3 years preceding the introduction of an electronic record system and the first 6 to 12 months of Haemoassist use. Data from the 3-year period were averaged. Missing data for rounded 12 months of e-diary use were extrapolated to correspond to a full year.

Results Enhancement of 23% in record delivery was observed for the period of Haemoassist use (p = 0.013). Twenty-one percent increase in patients’ compliance for data reporting (from 65% 35 to 86% 22, p = 0.003) and 16% increase for documentation of bleedings (from 68 to 84% of patients, p = 0.01) were detected. Compliance to prescribed therapy of patients for the whole studied period improved by 6% (from 82% ± 29 to 88% ± 25, p = 0.05). Major advances were demonstrated predominantly in the age groups of between 13 and 20 and 21 and 40 years.

Conclusion e-Diaries' use enables improved recording of information about patients' home treatment and bleeding episodes. Enhanced compliance with therapy may be a further benefit.

Obesity in the global haemophilia population: prevalence, implications and expert opinions for weight management

Overweight and obesity may carry a significant disease burden for patients with haemophilia (PWH), who experience reduced mobility due to joint inflammation, muscle dysfunction and haemophilic arthropathy. This review aimed to define the prevalence and clinical impact of overweight/obesity in the global population of PWH. A detailed literature search pertaining to overweight/obesity in haemophilia in the last 15 years (2003-2018) was conducted, followed by a meta-analysis of epidemiological data. The estimated pooled prevalence of overweight/obesity in European and North American PWH was 31%. Excess weight in PWH is associated with a decreased range in motion of joints, accelerated loss of joint mobility and increase in chronic pain. Additionally, the cumulative disease burden of obesity and haemophilia may impact the requirement for joint surgery, occurrence of perioperative complications and the prevalence of anxiety and depression that associates with chronic illness. Best practice guidelines for obesity prevention and weight management, based on multidisciplinary expert perspectives, are considered for adult and paediatric PWH. Recommendations in the haemophilia context emphasize the importance of patient education and tailoring engagement in physical activity to avoid the risk of traumatic bleeding.

Euthanasia of laboratory mice: Are isoflurane and sevoflurane real alternatives to carbon dioxide?

In the European Union (EU) millions of laboratory mice are used and killed for experimental and other scientific purposes each year. Although controversially discussed, the use of carbon dioxide (CO₂) is still permitted for killing rodents according to the Directive 2010/63/EU. Within the scope of refinement, our aim was to investigate if isoflurane and sevoflurane are an appropriate alternative killing method to CO₂ in mice. Different concentrations of CO₂ (filling rates of 20%, 60%, 100%; CO₂ 20, 60, 100), isoflurane (Iso 2%, 5%) and sevoflurane (Sevo 4.8%, 8%) were compared in two mouse strains (NMRI, C57Bl/6J) using a broad spectrum of behavioral parameters, including the approach-avoidance test, and analyzing blood for stress parameters (glucose, adrenaline, noradrenaline). We focused in our study on the period from the beginning of the gas inlet to loss of consciousness, as during this period animals are able to perceive pain and distress. Our results show that only higher concentrations of CO₂ (CO₂ 60, 100) and isoflurane (5%) induced surgical tolerance within 300 s in both strains, with CO₂ 100 being the fastest acting inhalant anesthetic. The potency of halogenated ethers depended on the mouse strain, with C57Bl/6J being more susceptible than NMRI mice. Behavioral analysis revealed no specific signs of distress, e. g. stress-induced grooming, and pain, i. e. audible vocalizations, for all inhalant gases. However, adrenaline and noradrenaline plasma concentrations were increased, especially in NMRI mice exposed to CO₂ in high concentrations, whereas we did not observe such increase in animals exposed to isoflurane or sevoflurane. Escape latencies in the approach-avoidance test using C57Bl/6J mice did not differ between the three inhalant gases, however, some animals became recumbent during isoflurane and sevoflurane but not during CO₂ exposure. The rise in catecholamine concentrations suggests that CO₂ exposure might be linked to a higher stress response compared to isoflurane and sevoflurane exposure, although we did not observe a behavioral correlate for that. Follow-up studies investigating other fast-acting stress hormones and central anxiety circuits are needed to confirm our findings.

Fetal CD103+ IL-17-Producing Group 3 Innate Lymphoid Cells Represent the Dominant Lymphocyte Subset in Human Amniotic Fluid

Amniotic fluid (AF) surrounds the growing fetus, and cells derived from AF are commonly used for diagnosis of genetic diseases. Intra-amniotic infections are strongly linked to preterm birth, which is the leading cause of perinatal mortality worldwide. Surprisingly little is known, however, about mature hematopoietic cells in AF, which could potentially be involved in immune responses during pregnancy. In this study, we show that the dominating population of viable CD45⁺ cells in AF is represented by a subset of fetal CD103⁺ group 3 innate lymphoid cells (ILCs) producing high levels of IL-17 and TNF. Fetal CD103⁺ ILC3s could also be detected at high frequency in second-trimester mucosal tissues (e.g., the intestine and lung). Taken together, our data indicate that CD103⁺ ILC3s accumulate with gestation in the fetal intestine and subsequently egress to the AF. The dominance of ILC3s producing IL-17 and TNF in AF suggests that they could be involved in controlling intra-amniotic infections and inflammation and as such could be important players in regulating subsequent premature birth.

The Human NK Cell Response to Yellow Fever Virus 17D Is Primarily Governed by NK Cell Differentiation Independently of NK Cell Education

NK cells play an important role in the defense against viral infections. However, little is known about the regulation of NK cell responses during the first days of acute viral infections in humans. In this study, we used the live attenuated yellow fever virus (YFV) vaccine 17D as a human in vivo model to study the temporal dynamics and regulation of NK cell responses in an acute viral infection. YFV induced a robust NK cell response in vivo, with an early activation and peak in NK cell function at day 6, followed by a delayed peak in Ki67 expression, which was indicative of proliferation, at day 10. The in vivo NK cell response correlated positively with plasma type I/III IFN levels at day 6, as well as with the viral load. YFV induced an increased functional responsiveness to IL-12 and IL-18, as well as to K562 cells, indicating that the NK cells were primed in vivo. The NK cell responses were associated primarily with the stage of differentiation, because the magnitude of induced Ki67 and CD69 expression was distinctly higher in CD57(-) NK cells. In contrast, NK cells expressing self- and nonself-HLA class I-binding inhibitory killer cell Ig-like receptors contributed, to a similar degree, to the response. Taken together, our results indicate that NK cells are primed by type I/III IFN in vivo early after YFV infection and that their response is governed primarily by the differentiation stage, independently of killer cell Ig-like receptor/HLA class I-mediated inhibition or education.

Cutting edge: identification and characterization of human intrahepatic CD49a+ NK cells

Although NK cells are considered innate, recent studies in mice revealed the existence of a unique lineage of hepatic CD49a(+)DX5(-) NK cells with adaptive-like features. Development of this NK cell lineage is, in contrast to conventional NK cells, dependent on T-bet but not Eomes. In this study, we describe the identification of a T-bet(+)Eomes(-)CD49a(+) NK cell subset readily detectable in the human liver, but not in afferent or efferent hepatic venous or peripheral blood. Human intrahepatic CD49a(+) NK cells express killer cell Ig-like receptor and NKG2C, indicative of having undergone clonal-like expansion, are CD56(bright), and express low levels of CD16, CD57, and perforin. After stimulation, CD49a(+) NK cells express high levels of inflammatory cytokines but degranulate poorly. CD49a(+) NK cells retain their phenotype after expansion in long-term in vitro cultures. These results demonstrate the presence of a likely human counterpart of mouse intrahepatic NK cells with adaptive-like features.

Neoplasm-induced bleeding in inherited, heterozygous FXIII-A deficiency

Inherited mild factor XIII deficiency belongs to one of the most underdiagnosed bleeding disorders so far. This is, because most patients do not develop bleeding complications in daily life.

A man (age: 64 years) without a history of bleeding presented with painful swelling of neck, weight loss, anemia and episodic bleeding from the right tonsil necessitating tonsillectomy. Histologic and immunohistochemical evaluation revealed cytokeratinpositive epitheloid angiosarcoma. Blood coagulation status showed significantly elevated D-dimer and decreased FXIII levels (FXIII-activity 35%, FXIIIA-Ag 16–26%). Plasma mixing studies excluded neutralizing antibodies against FXIII.

A novel heterozygous F13A1 gene nonsense mutation (p.Glu103Ter, c.307G>T) was found confirming heterozygous FXIII-A deficiency. The same mutation was detected in two further asymptomatic relatives. For further clinical management the patient was transfused with FXIII-concentrate and showed an adequate increase of FXIII ruling out FXIII deficiency to be induced by increased turnover. Despite this haemostatic management and antifibrinolytic treatment the patient had to undergo several revisions due to delayed, Hb relevant bleeding after cervical lymph nodes extirpation and resection of tonsil. Two chemotherapy cycles with paclitaxel and palliative radiotherapy of the neck area were performed, but the patient died unfortunately two months after diagnosis.

It is a unique case showing the combination of a highly aggressive angiosarcoma and presence of inherited FXIII deficiency. It is also a rare example demonstrating the benefit of FXIII genotyping besides the expected acquired FXIII deficiency possibly due to neoplasm induced increased consumption by elevated crosslinking of fibrin fibers.

Neoplasm-induced bleeding in inherited, heterozygous FXIII-A deficiency

Inherited mild factor XIII deficiency belongs to one of the most underdiagnosed bleeding disorders so far. This is, because most patients do not develop bleeding complications in daily life. Patient, methods: A man (age: 64 years) without a history of bleeding presented with painful swelling of neck, weight loss, anemia and episodic bleeding from the right tonsil necessitating tonsillectomy. Histologic and immunohistochemical evaluation revealed cytokeratin-positive epitheloid angiosarcoma. Blood coagulation status showed significantly elevated D-dimer and decreased FXIII levels (FXIII-activity 35%, FXIIIA-Ag 16-26%). Plasma mixing studies excluded neutralizing antibodies against FXIII.

RESULTS

A novel heterozygous F13A1 gene nonsense mutation (p.Glu103Ter, c.307G>T) was found confirming heterozygous FXIII-A deficiency. The same mutation was detected in two further asymptomatic relatives. For further clinical management the patient was transfused with FXIII-concentrate and showed an adequate increase of FXIII ruling out FXIII deficiency to be induced by increased turnover. Despite this haemostatic management and antifibrinolytic treatment the patient had to undergo several revisions due to delayed, Hb relevant bleeding after cervical lymph nodes extirpation and resection of tonsil. Two chemotherapy cycles with paclitaxel and palliative radiotherapy of the neck area were performed, but the patient died unfortunately two months after diagnosis.

CONCLUSIONS

It is a unique case showing the combination of a highly aggressive angiosarcoma and presence of inherited FXIII deficiency. It is also a rare example demonstrating the benefit of FXIII genotyping besides the expected acquired FXIII deficiency possibly due to neoplasm induced increased consumption by elevated crosslinking of fibrin fibers.

Human Umbilical Cord-Derived Mesenchymal Stem Cells Utilize Activin-A to Suppress Interferon-γ Production by Natural Killer Cells

Following allogeneic hematopoietic stem cell transplantation (HSCT), interferon (IFN)-γ levels in the recipient's body can strongly influence the clinical outcome. Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) are lucrative as biological tolerance-inducers in HSCT settings. Hence, we studied the molecular mechanism of how UC-MSCs influence natural killer (NK) cell-mediated IFN-γ production. Allogeneic NK cells were cultured in direct contact with UC-MSCs or cell-free supernatants from mesenchymal stem cell (MSC) cultures (MSC-conditioned media). We found that soluble factors secreted by UC-MSCs strongly suppressed interleukin (IL)-12/IL-18-induced IFN-γ production by NK cells by reducing phosphorylation of STAT4, NF-κB, as well as T-bet activity. UC-MSCs secreted considerable amounts of activin-A, which could suppress IFN-γ production by NK cells. Neutralization of activin-A in MSC-conditioned media significantly abrogated their suppressive abilities. Till date, multiple groups have reported that prostaglandin (PG)-E2 produced by MSCs can suppress NK cell functions. Indeed, we found that inhibition of PGE2 production by MSCs could also significantly restore IFN-γ production. However, the effects of activin-A and PGE2 were not cumulative. To the best of our knowledge, we are first to report the role of activin-A in MSC-mediated suppression of IFN-γ production by NK cells.

Inhibitor development and management in three non-severe haemophilia A patients with T295A variant

Missense mutations are the most common F8 gene defects among the patients with non-severe haemophilia A. This type of mutation is typically associated with low (5%) inhibitor risk. In the present retrospective study we analysed the clinical data of 16 haemophiliacs with the T295A missense mutation treated at Bonn Haemophilia Centre. In total, three patients developed inhibitors: two patients experienced low-titer and one high-titer inhibitors. Both patients with low titer inhibitors underwent successful ITI. The third patient, at the age of 81, developed initially low-titer inhibitors (3 BU/ml) after rFVIII therapy because of knee surgery. He experienced spontaneous multiple large skin haematomas and haemarthrosis. Immunosuppressive therapy was not applicable because of the infectious origin of discitis (Th3-Th4). Immunoadsorption was performed, but the inhibitor titer increased up to 42 BU/ml nine weeks after termination. A successful treatment of discitis with antibiotics finally allowed a weekly therapy (four times) with rituximab (375 mg/m(2)). This resulted in a decrease of inhibitor titre to 0.7 BU/ml eight weeks after the fourth rituximab application. Patient had endogenous FVIII levels of 3-5%. Twelve months after rituximab therapy (after B cells recovery) he relapsed with low-titer inhibitors and therefore was treated with single rituximab dose (375 mg/m(2)) again. This resulted in his depletion of B cells, measurable endogenous FVIII levels and non measurable inhibitors. This study demonstrated T295A variant to be associated with significantly increased (3/16 patients, 17%) inhibitor development.

Long-term outcome of liver transplantation in HCV/HIV coinfected haemophilia patients. A single centre study of 10 patients

The outcome and clinical features during long term follow-up of 10 haemophilia patients (haemophilia A n = 9, haemophilia B n = 1), who underwent successful orthotopic liver transplantation (OLT) due to hepatitis associated liver disease, are summarised.

PATIENTS

Eight patients were HIV/HCV co-infected. Despite severe postoperative complications, which were not bleeding-associated, all patients survived OLT.

RESULTS

Long-term survival was 70% after in mean 8 years follow-up. Twelve years after OLT one patient developed a cyclosporine-induced nephropathy requiring haemodialysis. HIV-HAART was initiated in all patients after OLT, and allowed a successful HCV treatment in 6 patients. Factor VIII production was sufficient in mean 72 h after OLT and remained stable at subnormal to normal FVIII levels of in median 30% (range 14-96%) also during long-term follow-up. Post-OLT spontaneous bleeding events were rare compared to pre-OLT, therefore, the performance status improved in all patients.

DISCUSSION

OLT substitutes the hepatic FVIII but has no effect on the extra-hepatic endothelial FVIII production, suggesting that in case of severe tissue injury enhanced bleeding might occur. Additionally, after OLT there is no acute phase reaction of the FVIII protein. Therefore, our OLT patients received in case of a reduced FVIII activity a peri-interventional prophylactic short-term FVIII substitution in surgical and diagnostic interventions with high bleeding risk.

CONCLUSION

Bleeding and wound healing disturbances were not seen.

Role of gamma-secretase in human umbilical-cord derived mesenchymal stem cell mediated suppression of NK cell cytotoxicity

Background

Mesenchymal stem cells (MSCs) are increasingly considered to be used as biological immunosuppressants in hematopoietic stem cell transplantation (HSCT). In the early reconstitution phase following HSCT, natural killer (NK) cells represent the major lymphocyte population in peripheral blood and display graft-vs-leukemia (GvL) effects. The functional interactions between NK cells and MSCs have the potential to influence the leukemia relapse rate after HSCT. Until date, MSC-NK cell interaction studies are largely focussed on bone marrow derived (BM)-MSCs. Umbilical cord derived (UC)-MSCs might be an alternative source of therapeutic MSCs. Thus, we studied the interaction of UC-MSCs with unstimulated allogeneic NK cells.

Results

UC-MSCs could potently suppress NK cell cytotoxicity in overnight cultures via soluble factors. The main soluble immunosuppressant was identified as prostaglandin (PG)-E2. Maximal PGE2 release involved IL-1β priming of MSCs after close contact between the NK cells and UC-MSCs. Interestingly, blocking gamma-secretase activation alleviated the immunosuppression by controlling PGE2 production. IL-1 receptor activation and subsequent downstream signalling events were found to require gamma-secretase activity.

Conclusion

Although the role of PGE2 in NK cell-MSC has been reported, the requirement of cell-cell contact for PGE2 induced immunosuppression remained unexplained. Our findings shed light on this puzzling observation and identify new players in the NK cell-MSC crosstalk.

Electronic supplementary material

The online version of this article (doi:10.1186/s12964-014-0063-9) contains supplementary material, which is available to authorized users.

Deep intronic 'mutations' cause hemophilia A: application of next generation sequencing in patients without detectable mutation in F8 cDNA

BACKGROUND

In a small group of typical hemophilia A (HA) patients no mutations in the F8 coding sequence (cDNA) could be found. In the current study, we performed a systematic screening of genetic and non-genetic parameters associated with reduced FVIII:C levels in a group of mostly mild HA (only one moderate) patients with no detectable mutations in F8 cDNA.

METHODS

We determined FVIII and VWF activity and antigen levels and performed VWF-FVIII binding (VWF:FVIIIB) and VWF-collagen binding assays (VWF:CB) as well as VWF multimer analysis. VWF was completely sequenced to exclude mutations. The F8 locus, including the introns, was sequenced using overlapping long-range PCRs (LR-PCRs) combined with a next generation sequencing (NGS) approach. Moreover, the F8 mRNA was analyzed quantitatively and qualitatively by real-time PCR (qRT) and overlapping reverse transcription (RT) PCRs, respectively.

RESULTS

All VWF tests were normal. The LR-PCRs demonstrated the integrity of the F8 locus. Eight unique polymorphisms were found in the patients, with two being recurrent. Furthermore, RT-PCRs analysis confirmed that two of the unique variants create detectable new cryptic splice sites in the patients that result in the introduction of intronic DNA sequences into the mRNA and create premature stop codons.

CONCLUSION

By systematically excluding all possible causes of HA, we could with great certainty conclude that deep intronic mutations in F8, although rare, cause abnormal mRNA splicing, leading to mild HA.

Differentiation and functional regulation of human fetal NK cells

The human fetal immune system is naturally exposed to maternal allogeneic cells, maternal antibodies, and pathogens. As such, it is faced with a considerable challenge with respect to the balance between immune reactivity and tolerance. Here, we show that fetal natural killer (NK) cells differentiate early in utero and are highly responsive to cytokines and antibody-mediated stimulation but respond poorly to HLA class I-negative target cells. Strikingly, expression of killer-cell immunoglobulin-like receptors (KIRs) did not educate fetal NK cells but rendered them hyporesponsive to target cells lacking HLA class I. In addition, fetal NK cells were highly susceptible to TGF-β-mediated suppression, and blocking of TGF-β signaling enhanced fetal NK cell responses to target cells. Our data demonstrate that KIR-mediated hyporesponsiveness and TGF-β-mediated suppression are major factors determining human fetal NK cell hyporesponsiveness to HLA class I-negative target cells and provide a potential mechanism for fetal-maternal tolerance in utero. Finally, our results provide a basis for understanding the role of fetal NK cells in pregnancy complications in which NK cells could be involved, for example, during in utero infections and anti-RhD-induced fetal anemia.

Function and regulation of human NK cells in an acute viral infection model (P6127)

Natural killer (NK) cells play an important role in shaping the immune response by releasing proinflammatory cytokines and direct lysis of malignant or virus-infected cells. However, very little is known about the earliest phases of the human NK cell response after acute infection in vivo. Here we made use of the yellow fever virus (YFV) vaccine strain 17D as an in vivo model of an acute viral infection in humans. Vaccination with the live attenuated 17D yellow fever strain induces a measurable viral load and strong T cell activation. YFV vaccination activated NK cells in vivo with distinct kinetics for different functions. NK cell activation as measured by upregulation of Ki67 peaked at day 10, whereas increased degranulation and cytokine production by NK cells peaked at day 6, and coincided with a peak in type I interferons and viral load. Interestingly, within the CD56dim NK cell population, activation was strongest in the least differentiated subset, but was independent of NK cell education via killer cell Ig-like receptors (KIRs). In conclusion, vaccination with 17D allows a detailed longitudinal analysis of NK cell activation after an acute viral infection in humans, and reveals a hierarchy of activation among different NK cell subsets.

Differential education of human fetal natural killer cells provides a mechanism for fetal-maternal tolerance. (P4458)

Little is known about the human fetal immune system, but it has for long been considered as immature and unresponsive. Here we have investigated the development and function of human fetal natural killer (NK) cells. Using advanced flow cytometry, the phenotype and function of fetal NK cells was examined. In contrast to the notion that the fetal immune system is immature, we found that human fetal NK cells differentiate as early as gestational week 15 in utero, evidenced by the presence of NK cells with decrease in CD94/NKG2A and increase in CD16 and KIR expression. NK cells with varying degrees of differentiation were found in the fetal lung, liver, spleen, lymph nodes and bone marrow. Moreover, we show that fetal NK cells are highly responsive to cytokine stimulation and are capable of killing target cells both via natural cytotoxicity and by antibody-dependent cellular cytotoxicity. Strikingly, and in contrast to the education of adult NK cells, we demonstrate that while education via CD94/NKG2A was established in fetal NK cells, both self- and non-self KIR expression rendered fetal NK cells hyporesponsive, thus potentially blunting the response to maternal allogeneic cells. Fetal NK cells were also found to be highly sensitive to TGF-β-mediated inhibition as compared to adult NK cells. Taken together, our data indicate a fundamental difference in the education and regulation of fetal compared to adult NK cells, which have implications for fetal-maternal tolerance in utero.

Human CD8(+) T cells and NK cells express and secrete S100B upon stimulation

Previous studies have demonstrated the utility of S100B as a surrogate marker of brain-related pathologies, e.g. neuropsychiatric disorders, and melanoma progression, which have an inflammatory component. This study addresses the relevance of S100B(+) lymphocytes in mediating such responses. S100B expression was determined in human peripheral blood leukocytes isolated from healthy volunteers using flow cytometry. S100B(+) lymphocytes were characterised for phenotype, cytokine production and S100B secretion. In addition, we investigated whether S100B activates monocytes and neutrophils. S100B(+) cells comprised 2-4% of all lymphocytes and the majority displayed a CD3(+) CD8(+) phenotype; fewer cells were CD3(-) CD56(+) NK lymphocytes. Comparison of S100B(+) and S100B(-) CD3(+) CD8(+) cells revealed no differences in production of interferon gamma (IFNγ) and interleukin-2 (IL-2). Stimulation of S100B(+) CD3(+) CD8(+) lymphocytes with anti-CD3 or phytohaemagglutinin resulted in release of S100B. High concentrations of recombinant human S100B triggered upregulation of CD11b and membrane shedding of CD62L in granulocytes and monocytes. These findings set the stage for a new field of research addressing a S100B-mediated crosstalk between the innate and adaptive immune systems if close proximity of effector and responder cells accomplishes sufficient local S100B levels. In various physiological and pathological conditions S100B might function as an interface to immunological processes, distinct from known cytokine- and chemokine-mediated pathways.

Optimization of culture conditions for the expansion of umbilical cord-derived mesenchymal stem or stromal cell-like cells using xeno-free culture conditions

First isolated from bone marrow, mesenchymal stem or stromal cells (MSC) were shown to be present in several postnatal and extraembryonic tissues as well as in a large variety of fetal tissues (e.g., fatty tissue, dental pulp, placenta, umbilical cord blood, and tissue). In this study, an optimized protocol for the expansion of MSC-like cells from whole umbilical cord tissue under xeno-free culture conditions is proposed. Different fetal calf sera and human serum (HS) were compared with regard to cell proliferation and MSC marker stability in long-term expansion experiments, and HS was shown to support optimal growth conditions. Additionally, the optimal concentration of HS during the cultivation was determined. With regard to cell proliferative potential, apoptosis, colony-forming unit fibroblast frequency, and cell senescence, our findings suggest that an efficient expansion of the cells is carried out best in media supplemented with 10% HS. Under our given xeno-free culture conditions, MSC-like cells were found to display in vitro immunoprivileged and immunomodulatory properties, which were assessed by co-culture and transwell culture experiments with carboxyfluorescein diacetate succinimidyl ester-labeled peripheral blood mononuclear cells. These findings may be of great value for the establishment of biotechnological protocols for the delivery of sufficient cell numbers of high quality for regenerative medicine purposes.

Murine CXCR3+CD27bright NK cells resemble the human CD56bright NK-cell population

Human NK cells can be subdivided into CD56(dim) and CD56(bright) NK cells, which exhibit different phenotypical and functional characteristics. As murine NK cells lack CD56 or a distinct correlate, direct comparative studies of NK cells in mice and humans are limited. Although CD27 is currently proposed as a feasible subset marker in mice, we assume that the usage of this marker alone is insufficient. We rather investigated the expression of the chemokine receptor CXCR3 for its suitability for distinguishing murine NK-cell subsets with simultaneous consideration of CD27. Compared with CXCR3(-) NK cells, exerting stronger cytotoxic capability, CXCR3+ NK cells displayed an activated phenotype with a lower expression of Ly49 receptors, corresponding to human CD56(bright) NK cells. Also in common with human CD56(bright) NK cells, murine CXCR3+ NK cells exhibit prolific expansion as well as robust IFN-gamma, TNF-alpha and MIP-1alpha production. We additionally demonstrated changes in both CXCR3 and CD27 expression upon NK-cell activation. In summary, CXCR3 serves as an additional applicable marker for improved discrimination of functionally distinct murine NK-cell subsets that comply with those in humans.

[Lactones. 22. Synthesis and reduction of alpha-aminomethylene-delta,delta-diphenyl-delta-valerolactones]

Treatment with tris-(dimethylamino)-methane resp. formylation and reaction with piperidine transfer 1 to 5a,b, which can not be reduced to the corresponding alpha-aminomethyllactones 4a,b, in contrast to the homologue 6 and other alpha-aminomethylene-gamma- and delta-lactones. Isolation of products and gc/ms-investigations verify the reaction course: The aminomethyl moiety in alpha-position of delta,delta-diarylated delta-lactones is instable and eliminates amine to give 7 (NaCNBH3) or 9 (H2/Pt). Only cleavage of the lactone ring enables the formation of stable aminomethyl compounds (10,11). 5a shows weak parasympatholytic and no H1-antihistaminic activity at the isolated guinea-pig ileum.