Somatic gene editing ameliorates skeletal and cardiac muscle failure in pig and human models of Duchenne muscular dystrophy.

Frameshift mutations in the DMD gene, encoding dystrophin, cause Duchenne muscular dystrophy (DMD), leading to terminal muscle and heart failure in patients. Somatic gene editing by sequence-specific nucleases offers new options for restoring the DMD reading frame, resulting in expression of a shortened but largely functional dystrophin protein. Here, we validated this approach in a pig model of DMD lacking exon 52 of DMD (DMDΔ52), as well as in a corresponding patient-derived induced pluripotent stem cell model. In DMDΔ52 pigs1, intramuscular injection of adeno-associated viral vectors of serotype 9 carrying an intein-split Cas9 (ref. 2) and a pair of guide RNAs targeting sequences flanking exon 51 (AAV9-Cas9-gE51) induced expression of a shortened dystrophin (DMDΔ51-52) and improved skeletal muscle function. Moreover, systemic application of AAV9-Cas9-gE51 led to widespread dystrophin expression in muscle, including diaphragm and heart, prolonging survival and reducing arrhythmogenic vulnerability. Similarly, in induced pluripotent stem cell-derived myoblasts and cardiomyocytes of a patient lacking DMDΔ52, AAV6-Cas9-g51-mediated excision of exon 51 restored dystrophin expression and amelioreate skeletal myotube formation as well as abnormal cardiomyocyte Ca2+ handling and arrhythmogenic susceptibility. The ability of Cas9-mediated exon excision to improve DMD pathology in these translational models paves the way for new treatment approaches in patients with this devastating disease.

Investigation of intra-herd spread of Mycobacterium caprae in cattle by generation and use of a whole-genome sequence.

Single nucleotide polymorphisms (SNPs) calculated from whole genome sequencing (WGS) are ideally suited to study evolutionary relationships of pathogens and their epidemiology. Mycobacterium caprae infections have been documented frequently in cattle and red deer along the Bavarian and Austrian Alps during the last decade. However, little is still known about the transmission within cattle holdings and possible alterations of the genomes of M. caprae during such events. The aim of this study was to study the molecular epidemiology of bovine tuberculosis (bTB) in selected herds based on isolate-specific genome-wide SNPs and to perform a phylogenetic network analysis. In total, 61 M. caprae isolates were collected originating from eight cattle farms over a period of twelve years between 2004 and 2015. Analysis of their sequence data revealed that the M. caprae isolates of an affected farm differ at all in a few SNPs. In contrast, many more SNPs were found when comparing the M. caprae genomes originating from different herds. The results demonstrated that the spread of bTB in the affected farms occurred by direct transmission between the members of each herd rather than between herds and a M. caprae introduction in farms after contact events e. g. on summer pastures can readily be traced by WGS analysis. Furthermore, we assembled a nearly complete whole genome sequence of M. caprae derived from several cattle isolates originating from bTB cases in the Bavarian Alpine region.

The Region of Difference Four is a Robust Genetic Marker for Subtyping Mycobacterium caprae Isolates and is Linked to Spatial Distribution of Three Subtypes.

Alpine Mycobacterium caprae isolates found in cattle and red deer display at least three genetic variations in the region of difference four (RD4) that can be used for further differentiation of the isolates into the subtypes 'Allgäu', 'Karwendel' and 'Lechtal'. Each genomic subtype is thereby characterized by a specific nucleotide deletion pattern in the 12.7-kb RD4 region. Even though M. caprae infections are frequently documented in cattle and red deer, little is known about the transmission routes. Hence, robust markers for M. caprae subtyping are needed to gain insight into the molecular epidemiology. For this reason, a rapid and robust multiplex PCR was developed for the simultaneous detection of three M. caprae RD4 subtypes and was used to subtype a total number of 241 M. caprae isolates from animals (145 cattle, 95 red deer and one fox) from Bavaria and Austria. All three subtypes occur spatially distributed and are found in cattle and in red deer suggesting transmission between the two species. As subtypes are genetically stable in both species it is hypothesized that the described genetic variations developed within the host due to 'within-host replication'. The results of this study recommend the genomic RD4 region as a reliable diagnostic marker for M. caprae subtype differentiation.

Trans-Atlantic exchanges have shaped the population structure of the Lyme disease agent Borrelia burgdorferi sensu stricto.

The origin and population structure of Borrelia burgdorferi sensu stricto (s.s.), the agent of Lyme disease, remain obscure. This tick-transmitted bacterial species occurs in both North America and Europe. We sequenced 17 European isolates (representing the most frequently found sequence types in Europe) and compared these with 17 North American strains. We show that trans-Atlantic exchanges have occurred in the evolutionary history of this species and that a European origin of B. burgdorferi s.s. is marginally more likely than a USA origin. The data further suggest that some European human patients may have acquired their infection in North America. We found three distinct genetically differentiated groups: i) the outgroup species Borrelia bissettii, ii) two divergent strains from Europe, and iii) a group composed of strains from both the USA and Europe. Phylogenetic analysis indicated that different genotypes were likely to have been introduced several times into the same area. Our results demonstrate that irrespective of whether B. burgdorferi s.s. originated in Europe or the USA, later trans-Atlantic exchange(s) have occurred and have shaped the population structure of this genospecies. This study clearly shows the utility of next generation sequencing to obtain a better understanding of the phylogeography of this bacterial species.

The transcription factor c-JUN/AP-1 promotes HBV-related liver tumorigenesis in mice.

Hepatocellular carcinoma (HCC) develops as a consequence of chronic inflammatory liver diseases such as chronic hepatitis B virus (HBV) infection. The transcription factor c-Jun/activator protein 1 (AP-1) is strongly expressed in response to inflammatory stimuli, promotes hepatocyte survival during acute hepatitis and acts as an oncogene during chemically induced liver carcinogenesis in mice. Here, we therefore aimed to characterize the functions of c-Jun during HBV-related liver tumorigenesis. To this end, transgenic mice expressing all HBV envelope proteins (HBV(+)), an established model of HBV-related HCC, were crossed with knockout mice lacking c-Jun specifically in hepatocytes and tumorigenesis was analyzed. Hepatic expression of c-Jun was strongly induced at several time points during tumorigenesis in HBV(+) mice, whereas expression of other AP-1 components remained unchanged. Importantly, formation of premalignant foci and tumors was strongly reduced in HBV(+) mice lacking c-Jun. This phenotype correlated with impaired hepatocyte proliferation and increased expression of the cell cycle inhibitor p21, whereas hepatocyte survival was not affected. Progression and prognosis of HBV-related HCC correlates with the expression of the cytokine osteopontin (Opn), an established AP-1 target gene. Opn expression was strongly reduced in HBV(+) livers and primary mouse hepatocytes lacking c-Jun, demonstrating that c-Jun regulates hepatic Opn expression in a cell-autonomous manner. These findings indicate that c-Jun has important functions during HBV-associated tumorigenesis by promoting hepatocyte proliferation as well as progression of dysplasia. Therefore, targeting c-Jun may be a useful strategy to prevent hepatitis-associated tumorigenesis.

The target cell of transformation is distinct from the leukemia stem cell in murine CALM/AF10 leukemia models.

The CALM/AF10 fusion gene is found in various hematological malignancies including acute myeloid leukemia (AML), T-cell acute lymphoblastic leukemia and malignant lymphoma. We have previously identified the leukemia stem cell (LSC) in a CALM/AF10-driven murine bone marrow transplant AML model as B220+ lymphoid cells with B-cell characteristics. To identify the target cell for leukemic transformation or 'cell of origin of leukemia' (COL) in non-disturbed steady-state hematopoiesis, we inserted the CALM/AF10 fusion gene preceded by a loxP-flanked transcriptional stop cassette into the Rosa26 locus. Vav-Cre-induced panhematopoietic expression of the CALM/AF10 fusion gene led to acute leukemia with a median latency of 12 months. Mice expressing CALM/AF10 in the B-lymphoid compartment using Mb1-Cre or CD19-Cre inducer lines did not develop leukemia. Leukemias had a predominantly myeloid phenotype but showed coexpression of the B-cell marker B220, and had clonal B-cell receptor rearrangements. Using whole-exome sequencing, we identified an average of two to three additional mutations per leukemia, including activating mutations in known oncogenes such as FLT3 and PTPN11. Our results show that the COL for CALM/AF10 leukemia is a stem or early progenitor cell and not a cell of B-cell lineage with a phenotype similar to that of the LSC in CALM/AF10+ leukemia.

Renal grafts from anti-hepatitis B core-positive donors: a quantitative review of the literature.

BACKGROUNDS AND AIMS: Organ shortage is a major problem in transplantation. The use of organs from hepatitis B surface antigen (HBsAg)-negative and hepatitis B core antibody (HBcAb)-positive donors could significantly increase the donor pool. However, little information is available about the impact of HBcAb status of renal donors on viral transmission to recipients. To address this issue, the present quantitative review of relevant studies has been performed. MATERIALS AND METHODS: Electronic databases including Medline, EMBASE, ISI, and Scopus were systematically searched for studies that evaluated risk of hepatitis B virus (HBV) transmission through renal transplantation from HBsAg-/HBcAb+ donors. Eligible studies were identified according to predefined criteria. The final outcome was one of HBV markers seroconversion defined as HBsAg, hepatitis B surface antibody (HBsAb), or HBcAb detection in previously seronegative end-stage renal disease (ESRD) patients after transplantation, and without other identified major sources of infection. RESULTS: Nine studies with 1385 eligible kidney recipients were included. In total, 45 subjects showed seroconversion of HBV markers as follows: HBsAg (n = 4) (0.28%; 95% confidence interval [CI] 0.006; 0.57), HBcAb (n = 32), HBsAb (n = 5), and either HBcAb or HBsAb (n = 4). The total rate of seroconversion after renal transplantation was calculated to be 3.24% (95% CI: 2.31-4.18). CONCLUSION: Our review indicates that the risk of HBV transmission from HBcAb-positive kidney donors is extremely low. Therefore, kidneys from these donors can be transplanted safely into ESRD patients.

[Direct antiviral treatment strategies in chronic hepatitis C]. / Direkt antivirale Therapieansätze bei der chronischen Hepatitis C.

The standard antiviral therapy for chronic hepatitis C is pegylated interferon-alfa (PegIFN) and ribavirin since about 10 years. This treatment regimen leads to a sustained virological response (SVR) in 40-50 % of patients infected with HCV genotype 1 and in approx. 80 % of those infected with HCV genotype 2 or 3. In recent years, many direct antiviral agents (DAA) have been developed and are being explored in clinical studies. These antiviral agents target different viral proteins that are central for HCV replication, incl. the NS3/4A protease, NS5B polymerase, and the NS5A protein. The protease inhibitors telaprevir and boceprevir have recently been approved for the treatment of chronic HCV genotype 1 infection in combination with PegIFN and ribavirin. These triple therapies increase the SVR rates in HCV genotype 1 patients from 40-50 % to approx. 70 %. Other DAAs will likely be approved in the near future and may result in an IFN-free antiviral therapy.

Weight loss and severe jaundice in a patient with hyperthyroidism.

BACKGROUND: Thyrotoxicosis may significantly alter hepatic function and is associated with autoimmune disorders of the liver. CASE REPORT: We report the case of a thyrotoxic patient with Graves' disease and histologically established cholestatic hepatitis. Medical treatment of hyperthyroidism normalized liver function tests. CONCLUSIONS: In patients with elevated liver function parameters and jaundice of unknown origin, thyroid function should generally be tested. Moreover, medical treatment of hyperthyroidism with thyrostatics may cause severe hepatitis whereas untreated hyperthyroid patients are at risk of developing chronic liver failure.

Opioid-induced constipation in advanced illness: safety and efficacy of methylnaltrexone bromide.

Constipation, one of the major side effects of opiates used in palliative care, can impair patients' quality of life to a point where it prevents sufficient pain control. Methylnaltrexone is a novel µ-receptor antagonist, which does not pass the blood brain barrier. It is licensed to treat opiate induced constipation for patients with advanced diseases. This review article presents an overview of pharmacology and safety of its application, evidence of its efficacy and economic aspects of its use in clinical practice. Available data are limited but strongly suggest that methylnaltrexone causes laxation in less than 24 hours for at least half of those patients over the first two weeks of usage without impairing pain control or causing serious adverse effects. To avoid danger of gastrointestinal perforation it is contraindicated for patients at risk for that complication. More research is needed to evaluate its long-term efficacy and economic impact.

[A rare cause of an indistinct liver lesion in an elderly woman]. / Seltene Ursache einer unklaren Leberläsion bei einer 76-jährigen Patientin.

HISTORY: A 76-year-old woman was admitted with a two-months history of pain in the right upper abdomen and nausea. There was no disease or premedication in her history. INVESTIGATIONS: Labaratory tests revealed a normocytic anemia, elevated liver enzymes and signs of cholestasis. An MR of the abdomen showed a hyperperfused tumor in the liver segments IV, V and VIII, likely to be a hepatocellular carcinoma. However, tumor markers including AFP were not elevated. A liver biopsy revealed the final diagnosis of angiosarcoma. THERAPY AND COURSE: Because the tumor was not resectable transarterial chemoembolisation (TACE) with doxorubicin was performed with palliative intent. Six weeks later a CT scan revealed extensive tumor progression. Therefore no further causal tretament was performed. With best supportive care the patient died within 4 weeks after she had been discharged. Occupational history revealed that the woman had been exposed to polyvinylchloride for six years when she had worked in a factory producing varnish aerosol cans 44 years ago. CONCLUSION: Angiosarcomas of the liver are rare, highly malignant and diffuse infiltrating vascular tumors with rapid growth and poor prognosis. In patients who have been exposed to polyvinylchloride and present with an indistinct lesion of the liver an angiosarcoma should be considered.