Dominik J. Kaczmarek

An effective interferon-gamma-mediated inhibition of hepatitis C virus replication by natural killer cells is associated with spontaneous clearance of acute hepatitis C in human immunodeficiency virus-positive patients

Hepatitis C virus (HCV) coinfection is an increasing health problem in human immunodeficiency virus‐positive (HIV+) individuals. However, a considerable proportion of HIV+ patients manage to overcome acute hepatitis C (AHC) spontaneously. In the present study, we analyzed the role of natural killer (NK) cells in modulating the course of AHC in HIV+ patients. Twenty‐seven HIV+ patients with AHC (self‐limited course: n = 10; chronic course: n = 17), 12 HIV+ patients with chronic hepatitis C (CHC), 8 HIV monoinfected individuals, and 12 healthy controls were studied. NK cells were phenotypically analyzed by flow cytometry. Interferon‐gamma (IFN‐γ) secretion, degranulation (CD107a), and anti‐HCV (= inhibition of HCV replication) activity of NK subpopulations were analyzed using the HuH7A2HCVreplicon cell system. NK cell frequency did not differ significantly between HIV+ patients with chronic and self‐limited course of AHC. However, we found NK cells from patients with self‐limiting infection to be significantly more effective in inhibiting HCV replication in vitro than NK cells from patients developing CHC. Of note, antiviral NK cell activity showed no significant correlation with NK cell degranulation, but was positively correlated with IFN‐γ secretion, and blocking experiments confirmed an important role for IFN‐γ in NK cell‐mediated inhibition of HCV replication. Accordingly, NK cells from patients that spontaneously cleared the virus displayed a stronger IFN‐γ secretion than those developing chronic infection. Finally, we observed high expression of NKG2D and NKp46, respectively, to be associated with self‐limiting course of aHCV. Accordingly, we found that blocking of these NK cell receptors significantly impaired antiviral NK cell activity. Conclusion: Our data suggest a strong IFN‐γ‐mediated antiviral NK cell response to be associated with a self‐limited course of AHC in HIV+ patients. (Hepatology 2014;59:814–827)

Compartment-specific distribution of human intestinal innate lymphoid cells is altered in HIV patients under effective therapy

Innate lymphocyte cells (ILCs), a novel family of innate immune cells are considered to function as key orchestrators of immune defences at mucosal surfaces and to be crucial for maintaining an intact intestinal barrier. Accordingly, first data suggest depletion of ILCs to be involved in human immunodeficiency virus (HIV)-associated damage of the intestinal mucosa and subsequent microbial translocation. However, although ILCs are preferentially localized at mucosal surfaces, only little is known regarding distribution and function of ILCs in the human gastrointestinal tract. Here, we show that in HIV(-) individuals composition and functional capacity of intestinal ILCs is compartment-specific with group 1 ILCs representing the major fraction in the upper gastrointestinal (GI) tract, whereas ILC3 are the predominant population in ileum and colon, respectively. In addition, we present first data indicating that local cytokine concentrations, especially that of IL-7, might modulate composition of gut ILCs. Distribution of intestinal ILCs was significantly altered in HIV patients, who displayed decreased frequency of total ILCs in ileum and colon owing to reduced numbers of both CD127(+)ILC1 and ILC3. Of note, frequency of colonic ILC3 was inversely correlated with serum levels of I-FABP and sCD14, surrogate markers for loss of gut barrier integrity and microbial translocation, respectively. Both expression of the IL-7 receptor CD127 on ILCs as well as mucosal IL-7 mRNA levels were decreased in HIV(+) patients, especially in those parts of the GI tract with reduced ILC frequencies, suggesting that impaired IL-7 responses of ILCs might contribute to incomplete reconstitution of ILCs under effective anti-retroviral therapy. This is the first report comparing distribution and function of ILCs along the intestinal mucosa of the entire human gastrointestinal tract in HIV(+) and HIV(-) individuals.

Antibiotic resistance in healthcare-related and nosocomial spontaneous bacterial peritonitis.

Spontaneous bacterial peritonitis (SBP) can be life threatening in patients with liver cirrhosis. In contrast to community‐acquired SBP, no standard treatment has been established for healthcare‐related and nosocomial SBP.

A variant in the nuclear dot protein 52kDa gene increases the risk for spontaneous bacterial peritonitis in patients with alcoholic liver cirrhosis.

BACKGROUND Spontaneous bacterial peritonitis is frequently a fatal infection in patients with liver cirrhosis. We investigated if nuclear dot protein 52kDa (NDP52), a negative regulator of toll-like receptor (TLR) signalling and autophagy adaptor protein, might be involved. METHODS Two cohorts comprising 152 (derivation cohort) and 198 patients (validation cohort) with decompensated liver cirrhosis and 168 healthy controls were genotyped for the rs2303015 polymorphism in the NDP52 gene and prospectively followed-up for spontaneous bacterial peritonitis. RESULTS Overall, 57 (38%) patients in the derivation cohort and 77 (39%) in the validation cohort had spontaneous bacterial peritonitis. Cirrhosis was due to alcohol abuse in 57% of the derivation and 66% of the validation cohort. In patients with alcoholic cirrhosis, patients with spontaneous bacterial peritonitis had an increased frequency of the NDP52 rs2303015 minor variant in the derivation (p=0.04) and in the validation cohort (p=0.01). Multivariate analysis confirmed this minor variant (odds ratio 4.7, p=0.002) and the TLR2 -16934 TT variant (odds ratio 2.5, p=0.008) as risk factors for spontaneous bacterial peritonitis. In addition, presence of the NDP52 minor variant affected survival negatively. CONCLUSION Presence of the NDP52 rs2303015 minor variant increases the risk for spontaneous bacterial peritonitis in patients with alcoholic cirrhosis.

Hypoxia impairs anti-viral activity of natural killer (NK) cells but has little effect on anti-fibrotic NK cell functions in hepatitis C virus infection

BACKGROUND & AIMS Natural killer (NK) cells have been shown to exert anti-viral as well as anti-fibrotic functions in hepatitis C virus (HCV) infection. Previous studies, however, analyzed NK cell functions exclusively under atmospheric oxygen conditions despite the fact that the liver microenvironment is hypoxic. Here, we analyzed the effects of low oxygen tension on anti-viral and anti-fibrotic NK cell activity. METHODS Peripheral (n=34) and intrahepatic (n=15) NK cells from HCV(+) patients as well as circulating NK cells from healthy donors (n=20) were studied with respect to anti-viral and anti-fibrotic activity via co-culture experiments with HuH7 replicon cells and hepatic stellate cells, respectively. RESULTS Anti-viral activity of resting NK cells from healthy controls was not affected by hypoxia. However, hypoxia significantly reduced the response of healthy NK cells to cytokine stimulation. In contrast to healthy controls, we observed resting and cytokine activated peripheral NK cells from HCV patients to display a significantly decreased anti-viral activity when cultured at 5% or 1% oxygen, suggesting HCV NK cells to be very sensitive to hypoxia. These findings could be confirmed when intrahepatic NK cells were tested. Finally, we show that anti-fibrotic NK cell activity was not affected by low oxygen tension. CONCLUSIONS Our results show that anti-viral function of NK cells from HCV(+) patients is critically affected by a hypoxic microenvironment and, therefore, indicate that in order to obtain an accurate understanding of intrahepatic NK cell anti-HCV activity, the laboratory modelling should take into account the liver specific levels of oxygen.

HIV mono-infection is associated with an impaired anti-hepatitis C virus activity of natural killer cells.

Objective:Hepatitis C virus (HCV) infection in HIV(+) patients is associated with faster liver disease progression compared with HCV mono-infection. HIV-associated immune defects are considered to play an important role in this context. Here, we analyzed the effects of HIV infection on natural killer (NK)-cell-mediated anti-HCV activity. Design:NK cell phenotype and interferon gamma (IFN-&ggr;) production, NK cell-mediated inhibition of HCV replication and CD4+ T-cell/NK cell interactions were studied in treatment naive HIV (n = 22), and HIV patients under combined antiretroviral therapy (n = 29), compared with healthy controls (n = 20). Methods:NK cell-mediated inhibition of HCV replication was analyzed using the HuH7A2HCVreplicon model. IFN-&ggr; production of NK cells as well as interleukin-2 secretion of CD4+ T lymphocytes were studied by flow cytometry. Results:Peripheral blood mononuclear cells from HIV(+) patients displayed a significantly impaired anti-HCV activity, irrespective of combined antiretroviral therapy. This could in part be explained by HIV-associated decline in NK cell numbers. In addition, NK cell IFN-&ggr; production was significantly impaired in HIV infection. Accordingly, we found low frequency of IFN-&ggr;(+) NK cells in HIV(+) patients to be associated with ineffective inhibition of HCV replication. Finally, we show that CD4+ T-cell-mediated stimulation of NK cell IFN-&ggr; production was dysregulated in HIV infection with an impaired interleukin-2 response of NK cells. Conclusion:HIV infection has a strong suppressive effect on anti-HCV activity of NK cells. This may contribute to low spontaneous clearance rate and accelerated progression of HCV-associated liver disease observed in HIV(+) patients.

IL-28B Genetic Variants Determine the Extent of Monocyte-Induced Activation of NK Cells in Hepatitis C.

Background Immuno-genetic studies suggest a functional link between NK cells and λ-IFNs. We recently showed that NK cells are negative for the IFN-λ receptor IFN-λR1 and do not respond to IFN-λ, suggesting a rather indirect association between IL-28B genotype and NK cell activity. Methods A total of 75 HCV(+) patients and 67 healthy controls were enrolled into this study. IL-28B (rs12979860) and IFNL-4 (rs368234815) genotypes were determined by rtPCR. Total PBMC, monocytes, and NK cells were stimulated with IL-29, the TLR-7/8 agonist R848, or a combination of both. NK cell IFN-γ response was analysed by FACS. IL-12 and IL-18 secretion of monocytes was studied by ELISA. In blocking experiments anti-IL-12/anti-IL-18 were used. Results Following stimulation of total PBMCs with R848 we found NK cell IFN- γ responses to vary with the IL-28B genotype, with carriers of a T/T genotype displaying the lowest frequency of IFN-γ(+)NK cells. When isolated NK cells were studied no such associations were observed, indicating an indirect association between IL-28B genotype and NK cell activity. Accordingly, we found R848-stimulated monocytes of patients with a T/T genotype to be significantly less effective in triggering NK cell IFN- γ production than monocytes from carriers of a non-T/T genotype. In line with these findings we observed monocytes from T/T patients to secrete significantly lower concentrations of IL-12 than monocytes from non-T/T individuals. Conclusions Our data indicate that monocytes from carriers of an IL-28B T/T genotype display a reduced ability to stimulate NK cell activity and, thus, provide a link between IL-28B genotype and NK functions.

Alterations of the NK cell pool in HIV/HCV co-infection

Background A relevant proportion of human immunodeficiency virus (HIV) infected patients is co-infected with the hepatitis C virus (HCV). HCV co-infection in HIV-positive patients is associated with faster progression of liver disease in comparison to HCV mono-infection. Natural killer (NK) cells critically modulate the natural course of HCV infection. Both HIV and HCV mono-infection are associated with alterations of the NK cell pool. However, little data is available concerning phenotype and function of NK cells in HIV/HCV co-infection. Methods A total of 34 HIV/HCV co-infected, 35 HIV and 39 HCV mono-infected patients and 43 healthy control persons were enrolled into this study. All HIV-positive patients were under effective antiretroviral therapy. NK cell phenotype, IFN-γ production and degranulation were studied by flow cytometry. Results NK cell frequency in HIV/HCV co-infection was significantly lower than in healthy individuals but did not differ from HIV and HCV mono-infection. HIV/HCV co-infection was associated with significantly decreased expression of the maturation/differentiation markers CD27/62L/127 on NK cells but increased expression of CD57 compared to healthy controls. Of note, expression also differed significantly from HCV mono-infection but was similar to HIV mono-infection, suggesting a pronounced impact of HIV on these alterations. Similar findings were made with regard to the NK cell receptors NKG2A/C and NKp30. More importantly, NK cells in co-infection displayed a highly impaired functional activity with significantly lower IFN-γ production and degranulation than in healthy donors as well as HIV and HCV mono-infection, suggesting a synergistic effect of both viruses. Conclusions Our data indicate that HIV/HCV co-infection is associated with significant alterations of the NK cell pool, which might be involved in the rapid progression of liver disease in co-infected patients and which mainly reflect alterations observed in HIV mono-infection.

Adaptation of motor unit contractile properties in rat medial gastrocnemius to treadmill endurance training: Relationship to muscle mitochondrial biogenesis

This study aimed at investigating the effects of 2, 4 and 8 weeks of endurance training on the contractile properties of slow (S), fast fatigue resistant (FR) and fast fatigable (FF) motor units (MUs) in rat medial gastrocnemius (MG) in relation to the changes in muscle mitochondrial biogenesis. The properties of functionally isolated MUs were examined in vivo. Mitochondrial biogenesis was judged based on the changes in mitochondrial DNA copy number (mtDNA), the content of the electron transport chain (ETC) proteins and PGC-1α in the MG. Moreover, the markers of mitochondria remodeling mitofusins (Mfn1, Mfn2) and dynamin-like protein (Opa1) were studied using qPCR. A proportion of FR MUs increased from 37.9% to 50.8% and a proportion of FF units decreased from 44.7% to 26.6% after 8 weeks of training. The increased fatigue resistance, shortened twitch duration, and increased ability to potentiate force were found as early as after 2 weeks of endurance training, predominantly in FR MUs. Moreover, just after 2 weeks of the training an enhancement of the mitochondrial network remodeling was present as judged by an increase in expression of Mfn1, Opa1 and an increase in PGC-1α in the slow part of MG. Interestingly, no signs of intensification of mitochondrial biogenesis assessed by ETC proteins content and mtDNA in slow and fast parts of gastrocnemius were found at this stage of the training. Nevertheless, after 8 weeks of training an increase in the ETC protein content was observed, but mainly in the slow part of gastrocnemius. Concluding, the functional changes in MUs’ contractile properties leading to the enhancement of muscle performance accompanied by an activation of signalling that controls the muscle mitochondrial network reorganisation and mitochondrial biogenesis belong to an early muscle adaptive responses that precede an increase in mitochondrial ETC protein content.

Endoscopic Ultrasound-Guided Drainage and Treatment of Symptomatic Pancreatic Fluid Collection following Acute or Acute-on-Chronic Pancreatitis – A Single Center Case Series

INTRODUCTION Pancreatic fluid collection (PFC) is a common complication of acute pancreatitis. Endoscopic ultrasound (EUS)-guided drainage, which is often followed by direct endoscopic necrosectomy (DEN), has become the primary approach to treat PFC, including pancreatic pseudocysts (PP) and walled-off necrosis (WON). We aimed to determine retrospectively the short- and long-term results of patients treated in our endoscopy unit and to identify parameters that are associated with treatment efficacy and outcome. METHODS The data of 41 consecutive patients with post-pancreatitic PFC, who underwent endoscopic transmural intervention between 2014 and 2016, were analyzed retrospectively. After an initial EUS-guided puncture, one or more plastic stents were placed and DEN was performed if necrotic tissue remained. RESULTS The mean diameter of the PFC was 74.0 ± 4.8 mm. Of the PFCs, 29.3% were classified as PP and 70.7% as WON. Altogether, 196 transmural endoscopic procedures were performed, including 73 endoscopic necrosectomies in a subgroup of 21 patients (20 WON, 1 PP). Initial technical success was achieved in 97.6% of patients and the short-term clinical success rate was 90.2%. The long-term clinical success rate was 82.9%, since four patients died from septic shock and/or multiple organ failure and three patients developed recurrent PFC some months after the initial discharge from endoscopic treatment. Procedural complications were registered in 9 patients during 10 of 196 endoscopic procedures (5.1%): bleeding (6), cardiorespiratory insufficiency (2), perforation with pneumoperitoneum (1), aspiration with respiratory insufficiency (1), and non-perforating superficial damage of the gastric wall (1). Neither the size of the PFC nor the initial value of C-reactive protein (CRP) or other biochemical markers were correlated with efficacy or outcome of treatment. Only the cumulative number of days with CRP > 50 mg/L significantly correlated with the number of follow-up endoscopic sessions and DEN. Fungal colonization of PFC correlated significantly (p < 0.05) with the risk of mortality (44% vs. 0%), need for intensive care treatment (66.7% vs. 25%), and sepsis (55.6% vs. 12.5%). CONCLUSIONS We confirm that EUS-guided drainage followed by DEN in patients with solid necrotic material is an effective and relatively safe therapeutic approach. Prolonged elevation of CRP and fungal colonisation of the PFC are associated with a worse course of the disease.