1
|
Pham EA, Perumpail RB, Fram BJ, Glenn JS, Ahmed A, Gish RG. Future Therapy for Hepatitis B Virus: Role of Immunomodulators. CURRENT HEPATOLOGY REPORTS 2016; 15:237-244. [PMID: 27917363 PMCID: PMC5112294 DOI: 10.1007/s11901-016-0315-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although currently available therapies for chronic hepatitis B virus infection can suppress viremia and provide long-term benefits for patients, they do not lead to a functional cure for most patients. Advances in our understanding of the virus-host interaction and the recent remarkable success of immunotherapy in cancer offer new and promising strategies for developing immune modulators that may become important components of a total therapeutic approach to hepatitis B, some of which are now in clinical development. Among the immunomodulatory agents currently being investigated to combat chronic HBV are toll-like receptor agonists, immune checkpoint inhibitors, therapeutic vaccines, and engineered T cells. The efficacy of some immune modulatory therapies is compromised by high viral antigen levels. Cutting edge strategies, including RNA interference and CRISPR/Cas9, are now being studied that may ultimately be shown to have the capacity to lower viral antigen levels sufficiently to substantially increase the efficacy of these agents. The current advances in therapies for chronic hepatitis B are leading us toward the possibility of a functional cure.
Collapse
Affiliation(s)
- Edward A. Pham
- Department of Medicine, Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, CA USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA USA
| | - Ryan B. Perumpail
- Department of Medicine, Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, CA USA
| | - Benjamin J. Fram
- Department of Medicine, Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, CA USA
| | - Jeffrey S. Glenn
- Department of Medicine, Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, CA USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA USA
- Veterans Administration Medical Center, Palo Alto, CA USA
| | - Aijaz Ahmed
- Department of Medicine, Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, CA USA
| | - Robert G. Gish
- Department of Medicine, Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, CA USA
- Hepatitis B Foundation, Doylestown, PA USA
| |
Collapse
|
2
|
Li B, Sun S, Li M, Cheng X, Li H, Kang F, Kang J, Dörnbrack K, Nassal M, Sun D. Suppression of hepatitis B virus antigen production and replication by wild-type HBV dependently replicating HBV shRNA vectors in vitro and in vivo. Antiviral Res 2016; 134:117-129. [PMID: 27591142 DOI: 10.1016/j.antiviral.2016.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 07/07/2016] [Accepted: 08/07/2016] [Indexed: 02/08/2023]
Abstract
Chronic infection with hepatitis B virus (HBV), a small DNA virus that replicates by reverse transcription of a pregenomic (pg) RNA precursor, greatly increases the risk for terminal liver disease. RNA interference (RNAi) based therapy approaches have shown potential to overcome the limited efficacy of current treatments. However, synthetic siRNAs as well as small hairpin (sh) RNAs expressed from non-integrating vectors require repeated applications; integrating vectors suffer from safety concerns. We pursue a new concept by which HBV itself is engineered into a conditionally replicating, wild-type HBV dependent anti-HBV shRNA vector. Beyond sharing HBV's hepatocyte tropism, such a vector would be self-renewing, but only as long as wild-type HBV is present. Here, we realized several important aspects of this concept. We identified two distinct regions in the 3.2 kb HBV genome which tolerate replacement by shRNA expression cassettes without compromising reverse transcription when complemented in vitro by HBV helper constructs or by wild-type HBV; a representative HBV shRNA vector was infectious in cell culture. The vector-encoded shRNAs were active, including on HBV as target. A dual anti-HBV shRNA vector delivered into HBV transgenic mice, which are not susceptible to HBV infection, by a chimeric adenovirus-HBV shuttle reduced serum hepatitis B surface antigen (HBsAg) up to ∼4-fold, and virus particles up to ∼20-fold. Importantly, a fraction of the circulating particles contained vector-derived DNA, indicating successful complementation in vivo. These data encourage further investigations to prove antiviral efficacy and the predicted self-limiting vector spread in a small animal HBV infection model.
Collapse
Affiliation(s)
- Baosheng Li
- Chinese PLA Medical School, Chinese PLA General Hospital, 100853, Beijing, PR China; The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, 050082, PR China
| | - Shuo Sun
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, 050082, PR China; Troop 66220 of PLA, Xingtai, Hebei Province, 054000, PR China
| | - Minran Li
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, 050082, PR China; The Fourth Department of the Fifth Hospital, Shijiazhuang City, 050017, PR China
| | - Xin Cheng
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, 050082, PR China
| | - Haijun Li
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, 050082, PR China
| | - Fubiao Kang
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, 050082, PR China
| | - Jiwen Kang
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, 050082, PR China
| | - Katharina Dörnbrack
- Internal Medicine II/Molecular Biology, University Hospital Freiburg, D-79106, Freiburg, Germany
| | - Michael Nassal
- Internal Medicine II/Molecular Biology, University Hospital Freiburg, D-79106, Freiburg, Germany.
| | - Dianxing Sun
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, 050082, PR China.
| |
Collapse
|
4
|
The regulatory role of activating transcription factor 2 in inflammation. Mediators Inflamm 2014; 2014:950472. [PMID: 25049453 PMCID: PMC4090481 DOI: 10.1155/2014/950472] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 05/30/2014] [Indexed: 01/06/2023] Open
Abstract
Activating transcription factor 2 (ATF2) is a member of the leucine zipper family of DNA-binding proteins and is widely distributed in tissues including the liver, lung, spleen, and kidney. Like c-Jun and c-Fos, ATF2 responds to stress-related stimuli and may thereby influence cell proliferation, inflammation, apoptosis, oncogenesis, neurological development and function, and skeletal remodeling. Recent studies clarify the regulatory role of ATF2 in inflammation and describe potential inhibitors of this protein. In this paper, we summarize the properties and functions of ATF2 and explore potential applications of ATF2 inhibitors as tools for research and for the development of immunosuppressive and anti-inflammatory drugs.
Collapse
|