In a recent B Heppy episode on clinical trials, Dr. Yasmin Ibrahim, Public Health Program Director at the Hepatitis B Foundation, discussed the process of how clinical trials work and the importance of clinical research in moving forward public health programs and interventions.
What is a Clinical Trial?
A clinical trial (also called clinical research) is the process for approving new medications or devices for a known health condition or disease. When people hear the term clinical trial, they may hink immediately that participants of that trial are at risk. What most don’t know is that before a medication or medical device is tested on human beings, it must go through a very rigorous process with approval from regulatory authorities and agencies. This is why clinical trials go through phases of approval and safety checks in the research process. We have outlined the phases of clinical trials below to help provide an understanding of the process.
Pre-clinical or lab studies: Before the drug can be tested on human beings, it is thoroughly researched on living cells and then animals with similar biological makeup, to assess its efficacy (benefits) and safety.
Clinical Phase I: Researchers test a new drug or treatment on a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify any side effects.
Clinical Phase II: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Clinical Phase III: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Clinical Phase IV: Studies are done after the drug or treatment has been marketed to gather information on the drug’s effect in many different populations and determine any side effects associated with long-term use of the product or drug.
All new treatments must go through clinical trials before being approved for use by the United States Food and Drug Administration (FDA), European Medicine Agency (EMA) or any other local regulatory authorities depending on the country.
Advancing and Sustaining Public Health through Research
Clinical trials are important because they are the safest way to develop and discover new treatments that work to cure diseases or improve the health and quality of life of patients. Because clinical trials have very strict safety regulations, they also tell us if a treatment is safe for people to use.
Eligibility Criteria for Participation in Clinical Trials
Eligibility criteria for clinical trials depends on the type of research being conducted. If a vaccine is being tested, then most participants are healthy to assess the response of the vaccine on the body’s immune system and the ability to produce protective antibodies. In some clinical trials that focus on certain populations or multiple conditions, the criteria may be more specific (e.g., testing the HBV treatments on people living with hepatitis B and diabetes). Study design and objectives determine participant eligibility and criteria.
Diversity and Inclusivity in Clinical Trials
Historically, clinical trials have neglected participation from minority populations and under-served communities. For example, sub-Saharan Africa has one of the highest burdens of hepatitis B globally, but clinical trials for hepatitis B are inadequate in those areas. The people who need access to clinical research the most are often denied access to these opportunities due to geographical barriers, lack of political will, regulatory issues, and other logistical challenges. It is important to ensure that all people who are directly impacted by hepatitis B should have access to participating in clinical trials and affording innovative therapies to improve their quality of life. There are steps that pharmaceutical and biotech companies, medical researchers, and public health organizations can take to diversify participation in clinical research. This involves including local patient-centered organizations and patient advocates in the clinical trial participation recruiting process. Partnering with a community is a helpful strategy to build trust with the community and engage people in research. Communication is integral to ensuring that participants fully understand the extent of their participation and the goals behind the research. Participants are encouraged to ask questions from the recruiters before agreeing to participate in the research.
Welcome to the Hepatitis B Research Review! This monthly blog shares recent scientific findings with members of Baruch S. Blumberg Institute (BSBI) labs and the hepatitis B (HBV) community. Technical articles concerning HBV, Hepatocellular Carcinoma, and STING proteinwill be highlighted as well as scientific breakthroughs in cancer, immunology, and virology. For each article, a brief synopsis reporting key points is provided as the BSBI does not enjoy the luxury of a library subscription. The hope is to disseminate relevant articles across our labs and the hep B community.
This paper from the University of Duisburg-Essen in Germany shows that hepatocytes infected with HBV exhibit innate immune signaling via the pattern precognition receptor (PRR) Toll-Like Receptor 2 (TLR2). The adaptive immune response to HBV infection is well characterized and is broken into phases based on serological testing of antibodies produced against the virus. However, whether HBV infection triggers an innate immune response has remained controversial, with the long-held belief being that HBV evades the innate immune system as a “stealth virus”. Contrary to this view, studies of acute HBV infection in patients have indicated an early, innate immune response to HBV characterized by a natural killer (NK) cell response. Toll-like receptors (TLRs) are a class of membrane-bound receptor proteins which play a key role in innate immunity by recognizing foreign pathogens and activating inflammatory signaling cascades. A previous publication from this group has demonstrated that primary human hepatocytes (PHHs) can be stimulated through the TLR proteins TLR1-9. In this paper, PHHs from human donors were infected with HBV ex vivo. Then, expression of the innate immune cytokines Interleukin 1 Beta (IL1B), Interleukin 6 (IL6), and Tumor Necrosis Factor Alpha (TNFα) were measured by quantitative, reverse-transcription polymerase chain reaction (qRT-PCR). HBV-infected PHHs showed greatly increased expression of these genes at three hours after infection compared to mock-infected and not treated PHHs. Additionally, immunocytochemical staining revealed translocation of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) to the nuclei of HBV-infected PHHs, indicating a cytokine response. Next, to characterize the innate immune response caused by HBV infection, a DNA microarray was used. Here, PHHs were either infected with HBV or treated with a known TLR ligand such as Pam3Cys (TLR2 agonist) or poly(I:C) (TLR3 agonist). Then, RNA was extracted from the cells and converted through a complementary DNA (cDNA) intermediate into biotin-labeled anti-sense RNA (aRNA) which was then hybridized to a Human Genome U219 Array Plate. This plate, coated with over 530,000 DNA probes representing over 20,000 human genes served as a scaffold for complementary base-pair binding of the aRNAs derived from the cells. Once bound to the microarray, the biotin-labeled aRNAs were detected by staining with streptavidin phycoerythrin, resulting in a fluorescent signal wherever complementary base-paring occurred. This microarray analysis revealed which specific inflammatory genes were up-regulated in the PHHs by each stimuli. Gene expression signals which were induced by HBV infection were compared with those induced by the TLR agonists. The gene expression profile of HBV-infected PHHs was most similar to that of PHHs treated with the TLR2 agonist Pam3Cys. This data indicates that HBV infection induces a TLR2-like innate immune response. Importantly, no expression of interferon-stimulated genes (ISGs) was detected in the microarray analysis. Finally, PHHs were pre-treated with neutralizing antibodies against TLR2 (nABTLR2) prior to infection with HBV. HBV-mediated induction of IL1B, IL6 and TNF was significantly reduced by nABTLR2 pre-treatment and conversely, HBV replication was increased. In summary, this paper shows that PHHs exhibited an innate immune response to HBV infection via the TLR2 pathway. The group suggests that this response is one of the body’s first steps leading to HBV clearance. Furthermore, in the discussion section the group indicates that the HBV surface antigen (HBsAg) is likely the protein component of HBV which activates TLR2 upon infection. This finding may help in the development of strategies to cure chronic HBV infection.
This paper from Wuhan University in China reports that HBV infection can increase the expression of Programmed Death Ligand 1 (PD-L1) on the surface of infected hepatocytes, allowing them to escape destruction by the adaptive immune system. PD-L1 is the binding partner of Programmed Death 1 (PD-1), an immune checkpoint protein on the surface of T cells. The expression of PD-L1 on cell surfaces allows for their recognition by circulating T cells as part of the body and not an outside threat. This interaction is important for the prevention of autoimmune disorders in which the immune system attacks healthy cells of the body. However, PD-L1 is commonly over-expressed in a number of cancers and is a hallmark of especially aggressive cancers. PD-L1 expression on cancer cells allows them to neutralize T cells which specifically target them. This is one example of an “immune-escape” strategy exhibited by cancers. Accordingly, PD-L1 and PD-1 are the target of a number of FDA approved immunotherapies for cancer including the PD-L1 inhibitors Tecentriq, Bavencio, and Imfinzi and the PD-1 inhibitors Keytruda, Opdivo, and Libtayo. These drugs are some of the first in their class in that they are not small molecules, but are recombinant, monoclonal antibodies. Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor which is mutated or deleted in many human cancers. PTEN is a phosphatase, a protein which dephosphorylates other molecules. This group has previously shown that PTEN plays a role in antiviral innate immunity. Therefore, they wanted to see if PTEN also regulates the adaptive immune response in the context of HBV infection. First, they used immunohistochemical staining of patient liver tissues to compare the levels of PTEN and PDL-1 in patients chronically infected with HBV vs healthy controls. There was a reduced staining of PTEN and a heightened staining of PD-L1 in chronic HBV tissues compared to controls. The group then found a similar correlation using immunofluorescence, qPCR and Western blotting of HepG2 cells vs HepG2.2.15 (HBV-producing) cells. They also transfected HepG2 cells and infected mice via hydrodynamic injection with an HBV-containing vector (pHBV1.3) or an empty vector control (pUC18) and then performed qPCR and/or Western blotting. In all systems, HBV infection/production induced a reduction of PTEN and an increase in PD-L1 expression. Then, in order to elucidate this phenomenon further, a PTEN-expressing plasmid was transfected into HepG2.2.15 cells, which resulted in a reduction in PD-L1 mRNA and protein. Conversely, PTEN knockdown in HepG2.2.15 cells resulted in a two-fold increase in PD-L1 mRNA and protein expression. These results show that HBV inhibits PTEN expression which in turn causes up-regulation of PD-L1. Next, the group transfected HepG2 and Huh7 cells with a number of constructs conferring individual HBV proteins. They found that HBV X protein (HBx) and HBV polymerase (HBp) reduced PTEN expression more than any other HBV protein components. Next, the group analyzed how HBV production in hepatocytes affected human T cells grown in co-culture. Jurkat T cells were co-cultured with either HepG2 or HepG2.2.15 cells and then analyzed by flow cytometry. Jurkat T cells grown alongside the HBV-producing HepG2.2.15 cells had a higher incidence of apoptosis, a higher expression of PD-1, and less Interleukin-2 (IL-2) secretion than those grown alongside HepG2 cells. This result indicates that HBV-infected hepatocytes suppress local T cell responses by PD-L1/PD-1 signaling. Finally, the group used a mouse model of HBV infection to show that PTEN over-expression promotes HBV clearance in vivo. This paper shows that PD-L1, a highly studied drug target implicated in the immune-escape of cancers is also up-regulated by HBV infection. Furthermore, the HBV proteins responsible for this up-regulation are HBx and HBp. This finding may help in the development of immunotherapies to treat chronic HBV infection. Perhaps FDA approved PD-L1 or PD-1 inhibitors may be used in conjunction with interferon alpha treatment or HBV antivirals to boost the immune response against HBV-infected hepatocytes.
This paper from National Tsing Hua University in Hsinchu, Taiwan reports the design and testing of nanoparticles which selectively confer immunogene therapy to hepatocellular carcenoma (HCC) cells. Nanoparticles are very small (1-1000nm) particles which have become an attractive novel drug candidate in recent years. The use of nanoparticles as medicine would enable the customizable delivery of DNA, RNA, or protein payloads to cells. The novel nanoparticles presented here deliver both a small interfering RNA (siRNA) against the Programmed Death Ligand 1 (PD-L1) gene as well as a plasmid DNA (pDNA) encoding the cytokine Interleukin 2 (IL-2). The strategy behind the nanoparticles’ design is to both inhibit an immunosuppressive gene (PD-L1) and up-regulate an immunostimmulatory gene (IL-2) in tumor cells. Delivery of such genes to tumor cells would make them more vulnerable to destruction by circulating cytotoxic T cells (CD8+ T cells). This type of approach is needed, because many advanced tumors create an immunosuppressive tumor micro-environment (TME) rendering many cancer treatments ineffective. The nanoparticles presented here are referred to as tumor-targeted lipid dendrimer-calcium phosphate (TT-LDCP) nanoparticles. The nanoparticles consist of a core of calcium phosphate, thymine-capped polyamidomine (PAMAM) dendrimers, siRNA, and pDNA. This core is coated with an inner lipid called DOPA and outer leaflet lipids DOPC, DOTAP, and DSPE-PEG. The nanoparticle is then tagged with SP94 (SFSIIHTPILPL), a polypeptide which selectively binds to HCC cells but not healthy hepatocytes. Dendrimers are repeatedly-branching molecules which exhibit a sphere-like shape. PAMAMs are the most well-characterized class of dendrimers, consisting of branching amide and amine groups. The calcium phosphate and PAMAM dendrimers in the core of the TT-LDCP nanoparticle promote endosomal escape of the nucleic acid payload. Additionally, this group shows that the PAMAM dendrimers in TT-LDCP nanoparticles also activate the STING pathway. The group showed that STING was activated by treating mouse HCC cells HCA-1 with complete nanoparticles or those lacking the dendrimers. Cells treated with complete nanoparticles showed, by Western blot a higher level of both TBK1 and IRF3 phosphorylation than those treated with incomplete nanoparticles. Those cells treated with complete nanoparticles also displayed heightened transcription of the STING-triggered proinflammatory genes Ifnb,Ccl5, and Cxcl10 as measured by qPCR. Furthermore, the group showed that treatment using their nanoparticles of mice bearing orthotopic HCC implants resulted in dendritic cell maturation in those animals, regardless of the identity of the genes delivered. These results indicate that the dendrimers used in the TT-LDCP nanoparticles not only serve for efficient delivery of nucleic acids, but also as adjuvants that stimulate the STING pathway and activate tumor-infiltrating dendritic cells. This publication gives a glimpse into what future therapies for cancer may look like. The nanoparticle designed by this group is unique in that it has multiple functionalities: selectively targeting HCC cells, inhibiting PD-L1 expression, inducing IL-2 expression, and activating the STING pathway. Such a complex design is bound to require fine tuning before it can become a medicine. But a multi-target immunotherapeutic such as this may be exactly what is needed to help the body fight against aggressive, immunosupressive tumors.
Lay Summary: This month, the innate immune system was the focus of HBV research. Scientists hope to find how the innate immune system interacts with HBV during viral infection and proliferation. Doing so will shed light on host factors which lead to chronic infection and inform antiviral strategies. Notably, this month a human protein, MX2 was found to have potent anti-HBV activity by preventing cccDNA formation. Also, a microRNA encoded by HBV called HBV-miR-3 was found to activate the human innate immune system to limit HBV replication. This month, a paper studying woodchuck hepatitis virus (WHV) traked activation of the innate immune system as well as he adaptive immune system in an acute infection model. Also this month, concerning hepatocellular carcenoma (HCC), the alternative splicing of mRNA in tumors was found to vary in HCC patients based upon their risk factor (HBV, HCV, or alcohol). Finally, a review was published this month concerning STING, an innate immune protein which is not activated by HBV infection but which may prove a valuable tool for cancer treatment.
Meet our guest blogger, David Schad, B.Sc., Junior Research Fellow at the Baruch S. Blumberg Institute studying programmed cell death such as
apoptosis and necroptosis in the context of hepatitis B infection under the direction of PI Dr. Roshan Thapa. David also mentors high school students from local area schools as part of an after-school program in the new teaching lab at the PA Biotech Center. His passion is learning, teaching and collaborating with others to conduct research to better understand nature.
Welcome to the Hepatitis B Research Review! This monthly blog shares recent scientific findings with members of Baruch S. Blumberg Institute (BSBI) labs and the hepatitis B (HBV) community. Technical articles concerning HBV, Hepatocellular Carcinoma, and STING proteinwill be highlighted as well as scientific breakthroughs in cancer, immunology, and virology. For each article, a brief synopsis reporting key points is provided as the BSBI does not enjoy the luxury of a library subscription. The hope is to disseminate relevant articles across our labs and the hep B community.
This paper from Fudan University in Shanghai, Chinareports the interferon-induced GTPase MX2 as a host protein which inhibits HBV replication. Interferon alpha (IFN-α) is a type 1 interferon used in a subset of HBV-infected patients to help eradicate the virus. IFN-α treatment results in the activation of hundreds of genes known as interferon-stimulated genes (ISGs). Which ISGs are most important in eliminating HBV infection remain largely unknown. GTPases are a large family of hydrolase enzymes which convert guanosine triphosphate (GTP) to guanosine diphosphate (GDP). GTPases act as molecular switches in an array of cellular process including signal transduction, cell division and differentiation, and protein translocation. The myxovirus resistance (Mx) proteins are highly conserved, dynamin-like, large GTPases. Humans have two MX proteins: MX1 and MX2, both of which are known ISGs. While MX1 is known to have broad-spectrum antiviral activity against RNA viruses, MX2 has only recently been shown to inhibit human immunodeficiency virus 1 (HIV-1), hepatitis C virus (HCV), and hepesviruses. MX2 antiviral activity against HIV-1 and herpesviruses is mediated through MX2 binding to the capsid of invading viruses whereby it likely inhibits the uncoating of viral DNA. In HCV, MX2 was found to interact with non-structural protein 5A (NS5A) thereby inhibiting its localization to the endoplasmic reticulum (ER). MX1 has been reported to inhibit HBV replication by inhibiting nuclear export of viral RNas and/or trapping the HBV core protein indirectly. This study investigates the anti-HBV activity of MX2. First, the group compared the anti-HBV activity of MX2 to four other innate immune restriction factors: HNRNPU, SAMHD1, MOV10 and A3G. They co-transfected these genes along with the HBV genome into HUH-7 cells and then assessed HBV replication via Southern blot. MX2 was found to inhibit HBV replication the most, with 44% of viral DNA compared to the empty vector control. The group then used siRNA, Southern blot, Western blot, fractionation, and mutagenesis studies to elucidate the anti-HBV role of MX2. Overall, they found that MX2 significantly reduces HBV RNA levels and indirectly impairs cccDNA formation. MX2 was found to contribute substantially to the anti-HBV affect of IFN-α. Both the GTPase activity and oligomerization status of MX2 were found to be important in conferring its anti-HBV affect. In the future, MX2 and its related pathways may be exploited to help prevent the formation of and even eliminate cccDNA in those infected with HBV.
This paper from the Tianjin Medical University in China explains how an HBV-encoded microRNA (miRNA) activates the innate immune system in humans infected with the virus. miRNAs are short (21-25 nucleotides) sequences of mRNA which are mainly involved in post-transcriptional silencing of genes. miRNAs are produced in plants, animals, bacteria, and viruses. Typically, miRNA acts to silence protein translation from a messenger RNA (mRNA) by binding to the 3′ untranslated region (UTR) of the mRNA. This binding may result in the destabilization or cleavage of the mRNA or inhibit the function of the ribosome during translation. This group has identified an miRNA from the HBV genome called HBV-miR-3 which they have previously reported inhibits HBV replication by targeting the HBV mRNA transcript. In this paper, the group first shows that HBV-miR-3 is produced in an amount proportional to virus infection in vitro. They also show that HBV-miR-3 is secreted from cells in exosomes. Next, using both patient serum samples and in vitro assays, the group found a positive correlation between HBV-miR-3 production and IFN-α signaling pathways. In patient serum, levels of HBV-miR-3 positively correlated with levels of the hepatitis-related parameters alanine aminotransferase (ALT), aspartate transaminase (AST) and type I IFNs (IFN-α and IFN-β). In cell culture, they observed an increased expression of the IFN-α-induced antiviral effectors OAS-1, MX1, IFIT2 and IFIT3 in the context of HBV-miR-3 production. Further experiments indicated that HBV-miR-3 promotes IFN-α production by suppressing the expression of suppressor of cytokine signaling 5 (SOCS5), allowing for signal transducer and activator of transcription 1 (STAT1) to be activated by phosphorylation. Finally, the group shows that HBV-miR-3 released from infected cells in exosomes promotes polarization of the M1 macrophage phenotype. M1 or “classically activated” macrophages secrete high levels of pro-inflammatory cytokines and thereby fight pathogenic infections. Taken together, these results show that aside from directly limiting HBV replication, HBV-miR-3 also indirectly limits HBV infection by activating the host innate immune system. The virus may do this in order to adopt host miRNA-mediated antiviral machinery and thereby alleviate pathogenesis so that persistent and latent infection can continue. In the future, levels of HBV-miR-3 may be used as a diagnostic marker for HBV infection and may shed light on novel antiviral approaches.
This paper from Georgetown University in Washington, DC is a “woodchuck paper”. That is, it is an in vivo study of woodchucks infected with Woodchuck Hepatitis Virus (WHV). WHV infection is used as a model system for HBV infection in humans because WHV is similar to HBV. This type of study is beneficial, especially when studying the immune response to hepadnaviruses, because humans infected with HBV are typically asymptomatic in the early stage of infection and because it is not advisable to obtain liver biopsies from these patients. The woodchuck infection model offers a controlled infection with WHV at a known time-point, which can be monitored by regular blood tests and liver biopsies. When studying the immune response to hepadnaviruses, liver biopsies are necessary because the liver is the site of the infection. About 95% of adults infected with HBV “clear” the virus; that is, their immune system is able to fight off the virus completely, giving them life-long immunity. The other 5% become chronic carriers of HBV and are at a high risk for liver cirrhosis and hepatocellular carcinoma (HCC). However, 95% of infants infected with HBV become chronic carriers. Differences in the immune systems of adults vs infants have been attributed to this drastic difference in chronicity, but what specific components of the immune system are important in staving off chronic infection remain unknown. Overall, the data presented here indicate that there is an early, non-cytolytic control of WHV replication mediated by interferon gamma (IFN-γ) produced mainly by natural killer (NK) cells. This was followed by an adaptive immune response characterized by antibody production, a T-cell response, and cytolytic action of cytotoxic T lymphocytes (CTLs). This adaptive immune response led to both the decline of WHV as well as symptoms of acute hepatitis B (AHB) including sinusoidal and portal inflammation in the liver.
This paper from the University of Utah School of Medicine in Salt Lake City, Utah uses bioinformatics to examine how different risk factors for hepatocellular carcinoma (HCC) correlate with differential alternative splicing (AS) of tumor mRNAs. After a primary (precursor) mRNA transcript is produced in the nucleus by RNA polymerase, the transcript must “mature” by having regions called “exons” removed in a process called splicing. Splicing results in an mRNA transcript consisting entirely of “introns”. The mRNA is then capped at its 5′ end with a 7-methylguanosine residue and polyadenylated at its 3′ end with about 200 adenylate residues (poly-A tail). This mature mRNA is able to exit the nucleus and be translated into protein by a ribosome. Alternative splicing (AS) describes how one genomic region may code for many different protein variants (isoforms) by differential spicing of the primary mRNA transcript. A common mechanism of AS is “exon skipping”, where exons are included in some mature transcripts but not others. HCC has various risk factors including alchohol consumption and infection with hepatitis B or C viruses (HBV and HCV). This study used data from The Cancer Genome Atlas (TCGA) and the Genomic Data Commons (GDC) Data portal to analyze 218 patients with primary HCC associated with HBV (n = 95), HCV (n =47), or alcohol (n = 76). They used RNA sequencing (RNA-Seq) data to examine differences in AS between three groups: HBV vs. HCV, HBV vs. alcohol, and HCV vs. alcohol. 143 genes were identified with differential AS across these groups and these genes were found to be mainly involved in immune system, mRNA splicing-major pathway, and nonsense-mediated decay pathways.Of the 143 AS genes identified, eight and one gene were alternatively spliced specific to HBV and HCV respectively. The human leukocyte antigen genes HLA-A and HLA-C had differential AS in HBV-related HCC compared to both HCV- and alchohol-related HCC. HLA ptoteins are part of the major histocompatibility complex (MHC) class 1 surface proteins which present foreign antigens to the immune system. Also, exon 3 of the gene encoding inositol hexakisphosphate kinase 2 (IP6K2) was skipped more often in HBV-related HCC than in other groups. IP6K2 is known to be involved in cancer metastasis. This study represents the first investigation into how different risk factors of HCC may affect the AS status of specific genes.
This review from the Memorial Sloan Kettering Cancer Center in New York City covers current understanding of the cGAS-STING pathway in the context of cancer. While it is well known that the cGAS-STING pathway is an evolutionarily-conserved antiviral signaling platform, how this pathway is involved in tumorigenesis remains unclear. In preneoplastic (early tumor) cells, cGAMP produced in response to DNA damage is exported out of the cell to activate STING in neighboring antigen-presenting cells (APC). This activation results in the release of type 1 interferon (IFN) from the APC, which cross-primes natural-killer and CD8 T-cells to kill the preneoplastic cells. In this context, the cGAS-STING pathway plays a role in tumor surveillance by activating innate immunity to create “hot spots” of inflammation. However, there is also evidence that activation of the cGAS-STING pathway can contribute to tumorigenesis. In advanced, metastatic tumor cells, chronic activation of STING by chromosomal abnormalities leads to suppressed production of IFN and the upregulation of Nf-kB-driven pro-survival genes. This can drive chronic inflammation of the tumor as well as its metastasis to other locations in the body. Activation of the STING pathway in tumor cells may also allow for their immune evasion by inducing autophagy and upregulating expression of programmed death-ligand 1 (PD-L1). Another interesting finding mentioned in this review is a STING-independent form of cGAS activation which may drive tumorigenesis during cell division. During mitosis, cytoplasmic cGAS may bind to repeat sequences in the centromere regions of chromosomal DNA. Once bound, cGAS may interrupt the repair of sister chromatids by homologous recombination, causing aneuploidy in daughter cells, a hallmark of tumor cells. Of additional interest, mentioned in this review are several recent findings regarding the cGAS-STING pathway, including: cGAS can be activated by extracellular DNA entering the cell in exosomes; cGAS can be activated by “micronuclei” which are small nuclear compartments in the cytoplasm formed by chromosomal instability; cGAS-DNA complexes turn into a liquid phase to produce cGAMP; STING dimers oligomerize to form tetramers when activated; palmitoylation of STING has been proposed to recruit TANK binding kinase 1 (TBK1) and interferon regulatory factor 3 (IRF3).
Lay Summary: This month, the innate immune system was the focus of HBV research. Scientists hope to find how the innate immune system interacts with HBV during viral infection and proliferation. Doing so will shed light on host factors which lead to chronic infection and inform antiviral strategies. Notably, this month a human protein, MX2 was found to have potent anti-HBV activity by preventing cccDNA formation. Also, a microRNA encoded by HBV called HBV-miR-3 was found to activate the human innate immune system to limit HBV replication. This month, a paper studying woodchuck hepatitis virus (WHV) traked activation of the innate immune system as well as he adaptive immune system in an acute infection model. Also this month, concerning hepatocellular carcenoma (HCC), the alternative splicing of mRNA in tumors was found to vary in HCC patients based upon their risk factor (HBV, HCV, or alcohol). Finally, a review was published this month concerning STING, an innate immune protein which is not activated by HBV infection but which may prove a valuable tool for cancer treatment.
Meet our guest blogger, David Schad, B.Sc., Junior Research Fellow at the Baruch S. Blumberg Institute studying programmed cell death such as
apoptosis and necroptosis in the context of hepatitis B infection under the direction of PI Dr. Roshan Thapa. David also mentors high school students from local area schools as part of an after-school program in the new teaching lab at the PA Biotech Center. His passion is learning, teaching and collaborating with others to conduct research to better understand nature.
How far are we from finding a cure for hepatitis B? We are close, said Timothy Block, PhD, president and co-founder of the Hepatitis B Foundation and its research arm, the Baruch S. Blumberg Institute. He points out that hepatitis C, once thought to be incurable, is today cured with new combination treatments.
Image courtesy of suphakit73 at FreeDigitalPhotos.net.
Experts believe a cure for hepatitis B will also soon be developed. And the need for a cure has never been greater, with more than 240 million people worldwide living with chronic hepatitis B, causing 1 million deaths per year from related liver failure and liver cancer.
“Treatments are available,” explained Block, “but we have become a little too comfortable with the medications that are currently approved for use.” While these drugs are effective, interferon has many side effects and daily antivirals require lifelong use. These drugs work in only half of the infected population and reduce death rates by only about 40 to 70 percent.
What will a cure look like?
The available antivirals are similar and combining them offers no advantage. They have limited effectiveness against cccDNA, the seemingly indestructible “mini-chromosome” of the hepatitis B virus that continues to produce virus particles in infected liver cells, even in people being treated. A cure, therefore, would have to destroy or silence cccDNA and provide long-term immunity. Because one-drug treatments can lead to drug resistance, a cure would almost certainly involve combination therapy, similar to hepatitis C. Continue reading "Is a Cure for Hepatitis B Coming? Experts Say Yes"→
HBF is pleased to connect our blog readers to Christine Kukka’s monthly HBV Journal Review that she writes for the HBV Advocate. The journal presents the latest in hepatitis B research, treatment, and prevention from recent academic and medical journals. This month, the following topics are explored:
New Study Finds HBV Genotype E Responds Poorly to Entecavir
HBV Genotypes Help Tell the Human Story of Slavery in the Americas
Researchers Find Tenofovir Increases Hip Bone Loss in Older Patients
Decline in HBV RNA Indicates Who Loses HBeAg During Antiviral Treatment
Shortened Vaccination Schedule May Get More Drug Users Immunized
Primary Care Doctors Rarely Screen Patients for Cirrhosis
Tenofovir or Telbivudine Recommended for Pregnant Women with High Viral Loads
Access to Healthy Food Vital for HBV Patients, but Many Live in Food “Deserts”
Scientists Create Viable Liver Cells in a Lab for HBV Research
Nerve Damage Prompts Warning Against Telbivudine-Interferon Combo Treatment
HBV Journal Review
September 1, 2014
Volume 11, Issue 9 by Christine M. Kukka
New Study Finds HBV Genotype E Responds Poorly to Entecavir Experts know some hepatitis B virus (HBV) strains called genotypes respond better to interferon treatment than others, but now scientists are discovering that genotypes respond differently to antiviral treatment too.
HBV genotypes are found in different regions of the world and each evolved over centuries to have slightly different molecular make-ups with unique traits. Some carry a higher risk of liver damage and cancer, while other genotypes are less virulent.
In a recent study, Italian researchers compared how well patients with genotypes A, D and E fared after three years of treatment with the antiviral entecavir (Baraclude). All of the patients tested negative for the hepatitis B “e” antigen (HBeAg-negative). The scientists measured hepatitis B surface antigen (HBsAg) levels and HBV DNA (viral load) every three months during the first year of treatment and then every six months over the study period.
They found the rates of HBsAg declines resulting from antiviral treatment varied markedly between genotypes. They extrapolated how many years of entecavir treatment each genotype required before a patient would clear HBsAg and achieve undetectable viral load.
HBV genotype A: It would take on average 15.6 years of entecavir treatment for an HBeAg-negative patient with HBV genotype A to lose HBsAg. This genotype is found in northern Europe, North America, India and southern Africa.
HBV genotype D: It would take 17 years for genotype D patients to lose HBsAg. This strain is found primarily in Russia, the Middle East, the Mediterranean region, and India.
HBV genotype E: This genotype, found in Central Africa, responded the most poorly to entecavir. Scientists estimated it would take 24.6 years for these patients to lose HBsAg, according to the report published in the August issue of the Journal of Medical Virology.
HBV Genotypes Help Tell the Human Story of Slavery in the Americas Because HBV genotypes develop in specific regions around the world, their distribution around the world today can help tell the story of mass human migrations, including the enslavement and forced migration of millions of Africans to Brazil since the 1500s.
