New horizon for radical cure of chronic hepatitis B virus infection

About 250 to 350 million people worldwide are chronically infected with hepatitis B virus (HBV), and about 700000 patients per year die of HBV-related cirrhosis or hepatocellular carcinoma (HCC). Several anti-viral agents, such as interferon and nucleos(t)ide analogues (NAs), have been used to treat this disease. NAs especially have been shown to strongly suppress HBV replication, slowing the progression to cirrhosis and the development of HCC. However, reactivation of HBV replication often occurs after cessation of treatment, because NAs alone cannot completely remove covalently-closed circular DNA (cccDNA), the template of HBV replication, from the nuclei of hepatocytes. Anti-HBV immune responses, in conjunction with interferon-γ and tumor necrosis factor-α, were found to eliminate cccDNA, but complete eradication of cccDNA by immune response alone is difficult, as shown in patients who recover from acute HBV infection but often show long-term persistence of small amounts of HBV-DNA in the blood. Several new drugs interfering with the life cycle of HBV in hepatocytes have been developed, with drugs targeting cccDNA theoretically the most effective for radical cure of chronic HBV infection. However, the safety of these drugs should be extensively examined before application to patients, and combinations of several approaches may be necessary for radical cure of chronic HBV infection.

Interferon-γ: Promising therapeutic target in atherosclerosis

Atherosclerosis is a chronic inflammatory disorder of the vasculature and is the primary cause of cardiovascular disease (CVD). CVD is currently the world’s leading cause of death and the numbers are predicted to rise further because of a global increase in risk factors such as diabetes and obesity. Current therapies such as statins have had a major impact in reducing mortality from CVD. However, there is a marked residual CVD risk in patients on statin therapy. It is therefore important to understand the molecular basis of this disease in detail and to develop alternative novel therapeutics. Interferon-γ (IFN-γ) is a pro-inflammatory cytokine that is often regarded as a master regulator of atherosclerosis development. IFN-γ is able to influence several key steps during atherosclerosis development, including pro-inflammatory gene expression, the recruitment of monocytes from the blood to the activated arterial endothelium and plaque stability. This central role of IFN-γ makes it a promising therapeutic target. The purpose of this editorial is to describe the key role IFN-γ plays during atherosclerosis development, as well as discuss potential strategies to target it therapeutically.

Clostridium difficile infection aggravates colitis in interleukin 10-deficient mice

AIM: To investigate the effect of Clostridium difficile (C. difficile) infection in an interleukin 10-deficient (IL-10^-/-) mouse model of inflammatory bowel disease.

METHODS: Bone marrow-derived dendritic cells isolated from wild type (WT) and IL-10^-/-mice were stimulated for 4 h with C. difficile toxin A (200 μg/mL), and gene expression of interferon (IFN)-γ, IL-12 and IL-23 was determined by real-time reverse transcription polymerase chain reaction. WT and IL-10^-/- mice (n = 20 each) were exposed to an antibiotic cocktail for three days and then were injected with clindamycin (i.p.). Mice (n = 10 WT, 10 IL-10^-/-) were then challenged with oral administration of C. difficile (1 × 10⁵ colony forming units of strain VPI 10463). Animals were monitored daily for 7 d for signs of colitis. Colonic tissue samples were evaluated for cytokine gene expression and histopathologic analysis.

RESULTS: C. difficile toxin A treatment induced IFN-γ gene expression to a level that was significantly higher in BDMCs from IL-10^-/- compared to those from WT mice (P < 0.05). However, expression of IL-12 and IL-23 was not different among the groups. Following C. difficile administration, mice developed diarrhea and lost weight within 2-3 d. Weight loss was significantly greater in IL-10^-/- compared to WT mice (P < 0.05). C. difficile infection induced histopathologic features typical of colitis in both IL-10^-/- and WT mice. The histopathologic severity score was significantly higher in the IL-10^-/- than in WT mice (mean ± standard error; 5.50 ± 0.53 vs 2.44 ± 0.46; P < 0.05). This was accompanied by a significantly greater increase in IFN-γ gene expression in colonic tissues from IL-10^-/- than from WT mice challenged with C. difficile (P < 0.05).

CONCLUSION: These results indicate that colitis is more severe after C. difficile infection in IL-10^-/-mice, and that IFN-γ expression is involved in this process.

Controversial issues regarding the roles of IL-10 and IFN-γ in active/inactive chronic hepatitis B

According to the important roles played by cytokines in induction of appropriate immune responses against hepatitis B virus (HBV), Dimitropoulou et al have examined the important cytokines in their patients. They showed that the serum levels of interleukin 10 (IL-10) and interferon-γ (IFN-γ) were decreased in patients with HBeAg-negative chronic active hepatitis B compared with the inactive hepatitis B virus carriers (Dimitropoulou et al 2013). The controversy can be considered regarding the decreased serum levels of IFN-γ in the HBeAg-negative chronic active hepatitis B patients. They concluded that subsequent to decreased expression of IFN-γ, the process of HBV proliferation led to liver diseases. Previous studies stated that HBV is not directly cytopathic for the infected hepatocytes and immune responses are the main reason for destruction of hepatocytes (Chisari et al, 2010). Scientists believe that immune responses against HBV are stronger in active forms of chronic HBV infected patients than inactive forms (Zhang et al, 2012). Therefore, the findings from Dimitropoulou et al may deserve further attention and discussion. Additionally, downregulation of IL-10 in chronically active hepatitis B infected patients has also confirmed our claim. IL-10 is an anti-inflammatory cytokine and its expression is increased in inactive forms in order to downregulate immune responses (Arababadi et al, 2012). Thus, based on the results from Dimitropoulou et al, it can be concluded that increased immune responses in chronically active hepatitis B infected patients are related to declined expression of IL-10 and interestingly IFN-γ is not involved in induction of immune responses in these patients.

Differential gene expression of chemokines in KRAS and BRAF mutated colorectal cell lines: Role of cytokines

AIM: To study KRAS/BRAF mutations in colorectal-cancer (CRC) that influences the efficacy of treatment. To develop strategies for overcoming combination of treatment.

METHODS: Five colonic cell-lines were investigated: DLD-1 with KRAS (G13D) mutation, HT 29 and Colo 205 with BRAF (V600E) mutation as well as the wild type (Wt) cell-lines Caco2 and Colo-320. DLD-1 (KRAS), HT-29 (BRAF) and Caco2 (Wt) cell lines were treated with cytokines (TNFα 50 ng, IL-1β 1 ng and IFNγ 50 ng) and harvested at different time points (1-24 h). KRAS inhibition was performed by the siRNA-approach. Two colorectal cancer cells DLD-1 and Caco2 were used for KRAS inhibition. About 70% confluency were confirmed before transfection with small interferring RNA (siRNA) oligonucleotides. All the synthetic siRNA sequences were designed in our laboratory. Total RNA and protein was isolated from the cells for RT-PCR and Western blotting. Densitometry of the Western blotting was analyzed with the Image J software (NIH). Results are shown as mean ± SD.

RESULTS: RT-PCR analysis in non-stimulated cells showed a low basal expression of TNFα and IL-1β in the DLD-1 KRAS-mutated cell-line, compared to Caco2 wild type. No detection was found for IL-6 and IFNγ in any of the studied cell lines. In contrast, pro-angiogenic chemokines (CXCL1, CXCL8) showed a high constitutive expression in the mutated cell-lines DLD-1 (KRAS), HT-29 and Colo205 (BRAF), compared to wild type (Caco2). The anti-angiogenic chemokine (CXCL10) showed a high basal expression in wild-type, compared to mutated cell-lines. KRAS down-regulation by siRNA showed a significant decrease in CXCL1 and CXCL10 gene expression in the DLD-1 (KRAS) cell-line in comparison to wild type (Caco2) at 72 h after KRAS silencing. In contrast, the specific KRAS inhibition resulted in an up-regulation of CXCL1 and CXCL10. The results of our study show a higher expression of pro-angiogenic chemokines at basal level in mutated cell-lines, which was further increased by cytokine treatment.

CONCLUSION: To summarize, basal chemokine gene expression for pro-angiogenic chemokines was high in mutated as compared to wild type cell-lines. This reflects the likely existence of a different microenvironment in tumours consistent of wild type or mutated cells. This may help to rationalize the choice of molecular targets for suitable therapeutic investigation in clinical studies.

Schizandra arisanensis extract attenuates cytokine-mediated cytotoxicity in insulin-secreting cells

AIM: To explore the bioactivity of an ethanolic extract of Schizandra arisanensis (SA-Et) and isolated constituents against interleukin-1β and interferon-γ-mediated β cell death and abolition of insulin secretion.

METHODS: By employing BRIN-BD11 cells, the effects of SA-Et administration on cytokine-mediated cell death and abolition of insulin secretion were evaluated by a viability assay, cell cycle analysis, and insulin assay. The associated gene and protein expressions were also measured. In addition, the bioactivities of several peak compounds collected from the SA-Et were tested against cytokine-mediated β cell death.

RESULTS: Our results revealed that SA-Et dose-dependently ameliorated cytokine-mediated β cell death and apoptosis. Instead of suppressing inducible nitric oxide synthase/nitric oxide cascade or p38MAPK activity, suppression of stress-activated protein kinase/c-Jun NH2-terminal kinase activity appeared to be the target for SA-Et against the cytokine mix. In addition, SA-Et provided some insulinotropic effects which re-activated the abolished insulin exocytosis in cytokine-treated BRIN-BD11 cells. Finally, schiarisanrin A and B isolated from the SA-Et showed a dose-dependent protective effect against cytokine-mediated β cell death.

CONCLUSION: This is the first report on SA-Et ameliorating cytokine-mediated β cell death and dysfunction via anti-apoptotic and insulinotropic actions.

Evaluation of virus-specific cellular immune response in transplant patients

Virus-specific immune responses have a major impact on the outcome of the infection. Viral agents that are characterized by latency, such as herpesviruses and polyomaviruses, require a continuous immune control to reduce the extent of viral reactivation, as viral clearance cannot be accomplished, independently from the anti-viral treatment. In transplant patients, morbidity and mortality related to viral infections are significantly increased. In fact, the key steps of activation of T-cells are major target for anti-rejection immunosuppressive therapy and anti-viral immune response may be altered when infected cells and cellular effectors of immune response coexist in a transplanted organ. The role of cellular immune response in controlling viral replication and the main methods employed for its evaluation will be discussed. In particular, the main features, including both advantages and limitations, of available assays, including intracellular cytokine staining, major histocompatibility complex - multimer-based assays, Elispot assay, and QuantiFERON test, will be described. The potential applications of these assays in the transplant context will be discussed, particularly in relation to cytomegalovirus and polyomavirus BK infection. The relevance of introducing viro-immunological monitoring, beside virological monitoring, in order to identify the risk profile for viral infections in the transplant patients will allows for define a patient-tailored clinical management, particular in terms of modulation of immunosuppressive therapy and anti-viral administration.

Interferon-γ inhibits ghrelin expression and secretion via a somatostatin-mediated mechanism

AIM: To investigate if and how the proinflammatory cytokine interferon γ (IFNγ) affects ghrelin expression in mice.

METHODS: The plasma concentration of ghrelin, and gastric ghrelin and somatostatin expression, were examined in wild-type mice and mice infected with Helicobacter pylori (H. pylori). Furthermore, ghrelin expression was examined in two achlorhydric mouse models with varying degrees of gastritis due to bacterial overgrowth. To study the effect of IFNγ alone, mice were given a subcutaneous infusion of IFNγ for 7 d. Finally, the influence of IFNγ and somatostatin on the ghrelin promoter was characterized.

RESULTS: H. pylori infection was associated with a 50% reduction in ghrelin expression and plasma concentration. Suppression of ghrelin expression was inversely correlated with gastric inflammation in achlorhdyric mouse models. Subcutaneous infusion of IFNγ suppressed fundic ghrelin mRNA expression and plasma ghrelin concentrations. Finally, we showed that the ghrelin promoter operates under the control of somatostatin but not under that of IFNγ.

CONCLUSION: Gastric infection and inflammation is associated with increased IFNγ expression and reduced ghrelin expression. IFNγ does not directly control ghrelin expression but inhibits it indirectly via somatostatin.

CD2 deficiency partially prevents small bowel inflammation and improves parasite control in murine Toxoplasma gondii infection

AIM: To investigate whether bowel inflammation and/or parasite control is altered in the absence of the T cell adhesion molecule CD2.

METHODS: Wildtype (WT) and CD2 deficient (CD2^-/-) mice were infected with 100 cysts of Toxoplasma gondii (T. gondii) (ME49) by gavage. On d 7 after infection mice were killed. Necrosis and the number of parasites/cm ileum were determined. Cytokine levels of stimulated cells as well as sera were evaluated. Secondly, survival of WT vs CD2^-/- mice was analysed using Kaplan-Meier analysis.

RESULTS: CD2^-/- mice survived longer than WT mice (mean: 23.5 vs 7.1 d, P = 0.001). Further, CD2^-/- mice showed less weight loss and less ileal inflammation than WT mice at d 7 post infection. In addition, the number of parasites in the ileum was significantly lower in CD2^-/- mice than in WT mice (88 ± 12 vs 349 ± 58 cm, P < 0.01). This was paralleled by lower production of IFN-γ and IL-6 from TLA-stimulated mLN cells and increased IFN-γ production by splenocytes.

CONCLUSION: CD2 deficient mice are more resistant to T. gondii infection than WT mice. In contrast to most current immunosuppressive or biological therapies CD2 deficiency reduces intestinal inflammation and at the same time helps to control infection.

Inhibition of hepatitis B virus DNA replicative intermediate forms by recombinant interferon-γ

AIM: To evaluate the in vitro anti-HBV activity of recombinant human IFN-γ, alone and in combination with lamivudine.

METHODS: A recombinant baculovirus-HBV/HepG2 culture system was developed which could support productive HBV infection in vitro. Expression of HBsAg and HBeAg in infected HepG2 culture medium was detected by commercial enzyme immunoassays. HBV DNA replication intermediates were detected in infected cells by Southern hybridization and viral DNA load was determined by dot hybridization.

RESULTS: IFN-γ at 0.1 to 5 μg/L efficiently down regulated HBsAg expression in transduced HepG2 cells. At 5 μg/L, IFN-γ also suppressed HBV DNA replication in these cells. While treatment with a combination of lamivudine and IFN-γ showed no additive effect, sequential treatment first with lamivudine and then IFN-γ was found to be promising. In this culture system the best HBV suppression was observed with a pulse of 2 μmol/L lamivudine for two days, followed by 1 μg/L IFN-γ for another four days. Compared to treatment with lamivudine alone, the sequential use of 0.2 μmol/L lamivudine for two days, followed by 5 μg/L IFN-γ for six days showed a 72% reduction in HBV cccDNA pool.

CONCLUSION: This in vitro study warrants further evaluation of a combination of IFN-γ and lamivudine, especially in IFN-α non-responder chronic hepatitis B patients. A reduced duration of lamivudine treatment would also restrict the emergence of drug-resistant HBV mutants.

Relationship between IFN-γ gene polymorphism and susceptibility to intrauterine HBV infection

AIM: To explore the susceptibility of children to intrauterine HBV infection by studying the relationship between IFN-γ gene polymorphism, including IFN-γ+874A/T single nucleotide polymorphism(SNP) and CA repeat microsatellite polymorphism and intrauterine HBV infection.

METHODS: A TaqMan fluorescence polymerase chain reaction in the IFN-γ+874A/T single nucleotide polymorphism was tested in the intrauterine HBV infection group(group I) and the normal immune children group(group II). Capillary electrophoresis was performed in the above two groups to assay the IFN-γ CA repeat microsatellite polymorphism.

RESULTS: Frequencies of AA, AT and TT genotypes were 67.4%, 19.6% and 13.0% in the intrauterine HBV infection group, and 45.2%, 30.1% and 24.7% in the normal immune children group, respectively. A significant difference was found in the frequency distribution of IFN-γ+874 genotype between the two groups (χ² = 5.102, P = 0.02389). In the intrauterine HBV infection group the AA genotype was more common than in the normal immune group. Frequency of IFN-γ+874A allele was 77.17% in the intrauterine HBV infection group, and 60.27% in the normal immune children group. In the intrauterine HBV infection group the IFN-γ+874A allele was more common than in normal immune group. A significant difference was found in the frequency distribution between the two groups (χ² = 7.238, P = 0.02389, OR = 2.228, 95% CI = 1.244-3.992). (CA₁₂)⁺/(CA₁₂)⁺ of IFN-γ CA microsatellite polymorphism was 11.90% in the intrauterine HBV infection group and 26.47% in the normal immune children group. A significant difference was found in the frequency distribution between the two groups (χ² = 5.64, P = 0.0176). Frequency of IFN-γ CA repeat was 25% in the intrauterine HBV infection group and 43.38% in the normal immune children group. The frequency of IFN-γ CA repeat was less in the intrauterine HBV infection group than in normal immune group. A significant difference was found in the frequency distribution between the two groups (χ² = 7.548, P = 0.0060).

CONCLUSION: There is a relationship between IFN-γ+874A/T SNP and intrauterine HBV infection as well as between IFN-γ CA microsatellite polymorphism and intrauterine HBV infection. IFN-γ gene polymorphism might be important in determining individual’s susceptibility to intrauterine HBV infection.