In vitro effect of thymosin-alpha1 and interferon-alpha on Th1 and Th2 cytokine synthesis in patients with chronic hepatitis C

COVID-19 Therapeutic Options Under Investigation

Since its emergence in China in December 2019, COVID-19 has quickly spread around the globe causing a pandemic. Vaccination or the development of herd immunity seems the only way to slow down the spread of the virus; however, both are not achievable in the near future. Therefore, effective treatments to mitigate the burden of this pandemic and reduce mortality rates are urgently needed. Preclinical and clinical studies of potential antiviral and immunomodulatory compounds and molecules to identify safe and efficacious therapeutics for COVID-19 are ongoing. Two compounds, remdesivir, and dexamethasone have been so far shown to reduce COVID-19-associated death. Here, we provide a review of the potential therapeutic agents being considered for the treatment and management of COVID-19 patients.

A Reappraisal of Thymosin Alpha1 in Cancer Therapy

Thymosin alpha1 (Tα1), an endogenous peptide first isolated from the thymic tissue in the mid-sixties, has gained considerable attention for its immunostimulatory activity that led to its application to diverse pathological conditions, including cancer. Studies in animal models and human patients have shown promising results in different types of malignancies, especially when Tα1 was used in combination with other chemo- and immune therapies. For this reason, the advancements in our knowledge on the adjuvant role of Tα1 have moved in parallel with the development of novel cancer therapies in a way that Tα1 was integrated to changing paradigms and protocols, and tested for increased efficacy and safety. Cancer immunotherapy has recently experienced a tremendous boost following the development and clinical application of immune checkpoint inhibitors. By unleashing the full potential of the adaptive immune response, checkpoint inhibitors were expected to be very effective against tumors, but it soon became clear that a widespread and successful application was not straightforward and shortcomings in efficacy and safety clearly emerged. This scenario led to the development of novel concepts in immunotherapy and the design of combination protocols to overcome these limitations, thus opening up novel opportunities for Tα1 application. Herein, we summarize in a historical perspective the use of Tα1 in cancer, with particular reference to melanoma, hepatocellular carcinoma and lung cancer. We will discuss the current limitations of checkpoint inhibitors in clinical practice and the mechanisms at the basis of a potential application of Tα1 in combination protocols.

Thymosin α1 Interacts with Hyaluronic Acid Electrostatically by Its Terminal Sequence LKEKK

Thymosin α1 (Tα1), is a peptidic hormone, whose immune regulatory properties have been demonstrated both in vitro and in vivo and approved in different countries for treatment of several viral infections and cancers. Tα1 assumes a conformation in negative membranes upon insertion into the phosphatidylserine exposure as found in several pathologies and in apoptosis. These findings are in agreement with the pleiotropy of Tα1, which targets both normal and tumor cells, interacting with multiple cellular components, and have generated renewed interest in the topic. Hyaluronan (HA) occurs ubiquitously in the extracellular matrix and on cell surfaces and has been related to a variety of diseases, and developmental and physiological processes. Proteins binding HA, among them CD44 and the Receptor for HA-mediated motility (RHAMM) receptors, mediate its biological effects. NMR spectroscopy indicated preliminarily that an interaction of Tα1 with HA occurs specifically around lysine residues of the sequence LKEKK of Tα1 and is suggestive of a possible interference of Tα1 in the binding of HA with CD44 and RHAMM. Further studies are needed to deepen these observations because Tα1 is known to potentiate the T-cell immunity and anti-tumor effect. The binding inhibitory activity of Tα1 on HA-CD44 or HA-RHAMM interactions can suppress both T-cell reactivity and tumor progression.

Mechanism of Action of Thymosinα1: Does It Interact with Membrane by Recognition of Exposed Phosphatidylserine on Cell Surface? A Structural Approach

Thymosinα1 is a peptidic hormone with pleiotropic activity, which is used in the therapy of several diseases. It is unstructured in water solution and interacts with negative regions of micelles and vesicles assuming two tracts of helical conformation with a structural flexible break in between. The studies of the interaction of Thymosinα1 with micelles of mixed dipalmitoylphosphatidylcholine and sodium dodecylsulfate and vesicles with mixed dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylserine, the latter the negative component of the membranes, by (1)H and natural abundance (15)N NMR are herewith reported, reviewed, and discussed. The results indicate that the preferred interactions are those where the surface is negatively charged due to sodium dodecylsulfate or due to the presence of dipalmitoylphosphatidylserine exposed on the surface. In fact the unbalance of dipalmitoylphosphatidylserine on the cellular surface is an important phenomenon present in pathological conditions of cells. Moreover, the direct interaction of Thymosinα1 with K562 cells presenting an overexposure of phosphatidylserine as a consequence of resveratrol-induced apoptosis was carried out.

Thymosin alpha-1 with peginterferon alfa-2a/ribavirin for chronic hepatitis C not responsive to IFN/ribavirin: an adjuvant role?

This study was conducted to determine whether the adding thymosin alpha-1 to standard of care for re-treatment of nonresponding hepatitis C infections can improve sustained viral response (SVR) rates. Patients (n = 552) with hepatitis C infections not responding to the combination of Peginterferon alfa-2a or 2b with ribavirin (RBV)were randomized to receive peginterferon alfa-2a 180 mg/week with RBV 800-1200 mg/daily plus either thymosin alpha-1 1.6 mg SC twice weekly (n = 275) or placebo (n = 277) for 48 weeks. Eighty-eight per cent of patients had HCV genotype 1, 6.6% type 4, 2.2% type 2 and 3.6% type 3. SVR rates in the intention to treat population were similar between thymosin alpha-1 and placebo (12.7%vs 10.5%; P = 0.407). Among patients who completed all 48 weeks of therapy, the SVR rate was significantly higher in the thymosin alpha-1 group at 41.0% (34/83) compared with 26.3% (26/99) in the placebo group (P = 0.048). No significant difference was observed between treatment groups in the incidence of adverse events. The addition of thymosin alpha-1 to the standard of care did not increase the on-treatment HCV viral response. Thymosin alpha-1 seems to play no role in the primary therapy of the disease. This study raises the hypothesis that thymosin alpha-1 may have a secondary therapeutic role as an adjuvant in the prevention of relapses in patients achieving a virologic response during therapy.

NMR structure of human thymosin alpha-1

800 MHz NMR structure of the 28-residue peptide thymosin alpha-1 in 40% TFE/60% water (v/v) has been determined. Restrained molecular dynamic simulations with an explicit solvent box containing 40% TFE/60% TIP3P water (v/v) were used, in order to get the 3D model of the NMR structure. We found that the peptide adopts a structured conformation having two stable regions: an alpha-helix region from residues 14 to 26 and two double β-turns in the N-terminal twelve residues which form a distorted helical structure.

Effect of Thymosin-α1 on T-helper 1 Cell and T-helper 2 Cell Cytokine Synthesis in Patients with Hepatitis B Virus e Antigen-positive Chronic Hepatitis B

Thymosin-α1 (TA1) has been shown to be effective treatment for chronic hepatitis B virus (HBV) infection. This study investigated the immune response after TA1 monotherapy in 25 HBV e antigen (HBeAg)-positive patients randomized to receive either 1.6 mg active TA1 (group A), 1.6 mg recombinant TA1 (group B) or 3.2 mg recombinant TA1 (group C) monotherapy for 52 weeks. The percentages of T-helper 1 (Th1) cytokine-producing T-cells (interleukin-2 [IL-2], interferon-γ [IFN-γ], tumour necrosis factor-α) and Th2 cytokine-producing T-cells (IL-4) were analysed using flow cytometry. In all patients treated with TA1, cytokine levels and the proportion of peripheral blood mononuclear cells producing these cytokines were significantly increased, compared with baseline and healthy controls. The proportions of each cytokine-producing cell increased gradually over time and were restored to normal levels, and proportions of IFN-γ and IL-4-producing cells reached higher levels than in normal (healthy) controls. The results showed that treatment with TA1 increased cytokine production, especially IFN-γ, and higher-dose TA1 exhibited better efficacy against HBV, compared with other treatments studied.

Potential Role of Thymosin-alpha1 Adjuvant Therapy for Glioblastoma

Glioblastomas are high-grade, malignant CNS neoplasms that are nearly always fatal within 12 months of diagnosis. Immunotherapy using proinflammatory cytokines such as IL-2 or IL-12 may prolong survival with glioblastoma. Thymosin-α1 (Talpha1) is a thymic hormone and immunemodulator that increase IL-2 production and T-cell proliferation. We examined potential therapeutic effects of Talpha1 in experimental in vivo glioblastoma, and characterized Talpha1's anti-tumor effects in vitro. Rar 9L cells (10⁴) were implanted into the right frontal lobe of adult Long Evans rats that were subsequently treated with vehicle, BCNU, Talpha1, or Talpha1+BCNU from postoperative day 6. Talpha1+BCNU significantly lowered tumor burdens, and increased cure rates. In vitro experiments demonstrated that Talpha1 had no direct effect on viability or mitochondrial function, and instead, it increased expression of pro-apoptosis genes, including FasL, FasR and TNFα-R1 (65.89%, 44.08%, and 22.18%, resp.), and increased 9L cell sensitivity to oxidative stress. Moreover, Talpha1 enhanced 9L cell sensitivity to both Granzyme B- and BCNU-mediated killing. The findings suggest that Talpha1 enhances BCNUmediated eradication of glioblastoma in vivo, and that Talpha1 mediates its effects by activating pro-apoptosis mechanisms, rendering neoplastic cells more sensitive to oxidative stress and immune-mediated killing by Granzyme B and chemotherapeutic agents.

A New Immunomodulatory Therapy for Severe Sepsis: Ulinastatin Plus Thymosin α 1

Objectives: To study the effect of immunomodulatory therapy with ulinastatin plus thymosin α 1 on septic patients. Method: A total of 56 sepsis patients were randomized into a treatment group, receiving immunomodulatory therapy, and a placebo group, a placebo. Acute Physiology and Chronic Health Evaluation II scores, clinical data, lymphocyte subsets, immunological indexes, and coagulation parameters were determined before admission and on the 3rd, 8th, and 28th day after admission to the Intensive Care Unit. Results: The treatment group experienced a 78% cumulative survival, the placebo group experienced a 60% cumulative survival; the survival difference was mirrored by Acute Physiology and Chronic Health Evaluation II scores and more quickly improved leukocyte counts, lymphocyte counts, coagulation parameters, and cytokine levels in the treatment. Conclusions: Combined immunomodulatory therapy with ulinastatin plus thymosin α1 appears to yield improved survival for patients with sepsis; this finding should be verified in larger clinical trials.

In vitro effect of thymosin-alpha1 and interferon-alpha on Th1 and Th2 cytokine synthesis in patients with eAg-negative chronic hepatitis B

Thymosin alpha-1 (Talpha1) has been shown to be effective in chronic hepatitis B treatment. This study investigated the effect of Talpha1 and interferon-alpha (IFNalpha) on cytokine production by peripheral blood mononuclear cells (PBMCs) of 12 patients with eAg-negative chronic hepatitis B (HBV). We evaluated the effect of incubation with Talpha1, IFNalpha or both on the synthesis of T-helper 1 (Th1) cytokines [interleukin-2 (IL-2), IFNgamma] and Th2 cytokines (IL-4, IL-10) and of antiviral protein 2',5'-oligoadenylate synthetase (2',5'-OAS) in patients and in a group of 10 healthy controls. Concerning Th1 profile, controls showed lower IL-2 synthesis than HBV patients. In HBV setting, IFNalpha/Talpha1 combination was able to increase IL-2 production significantly, when compared with baseline condition. About the Th2-cytokines, controls showed statistically lower synthesis of IL-4 and higher production of IL-10, than HBV patients. In these latter, IFNalpha increased the synthesis of IL-10 compared with baseline. Interestingly, both Talpha1 alone and the IFNalpha/Talpha1 combination reversed this effect. Finally, compared with baseline, the synthesis of 2',5'-OAS was significantly higher in the presence of Talpha1 and IFNalpha alone, and in the presence of IFNalpha/Talpha1 association, while no differences were found between controls and HBV patients. In conclusion, in PBMCs from eAg-negative HBV patients, Talpha1 alone was able to increase the antiviral protein synthesis, while in association with IFNalpha, it stimulated the IL-2 synthesis and inhibited the IFN-induced IL-10 production. These results need further investigations, but reinforce the idea of an immunotherapeutic approach for chronic hepatitis B.

Thymosin Alpha-1 in Combination with Pegylated Interferon and Ribavirin in Chronic Hepatitis C Patients Who have Failed to Prior Pegylated Interferon and Ribavirin Treatment

Combination therapy with inteferon-alpha and ribavirin is an approved therapy for patients with chronic hepatitis C. However, even with the use of pegylated interferon, response rates are still poor in many difficult-to-treat groups, especially with genotype 1 and high viral loads. Retreatment of these patients remains challenging. Newer combinations are being investigated to optimize chances of attaining a sustained response in these groups. Thymosin alpha 1 is a polypeptide with immunomodulatory properties that has been suggested to increase response rates in patients with chronic hepatitis C. Herein, we describe two cases of retreatment patients with chronic hepatitis C who have failed prior pegylated interferon and ribavirin therapy. They received triple combination therapies of thymosin alpha 1, pegylated interferon and ribavirin and achieved sustained virological responses. These cases support that thymosin-alpha 1 may increase the efficacy of pegylated interferon plus ribavirin in the treatment of non-responders to previous combination therapy.

Hepatitis B virus genotype B is associated with better response to thymosin alpha1 therapy than genotype C

Hepatitis B virus (HBV) genotype has been reported to correlate with response to interferon treatment in several studies. The relationship between HBV genotype and thymosin alpha1 (T-alpha1) treatment is unknown. We retrospectively examine HBV genotypes, precore and core promoter mutations in patients treated with Talpha1 and analyse the correlation between complete response [alanine aminotransferase (ALT) normalization plus seroclearance of HBeAg and HBV-DNA] and HBV genotype. It consisted 98 patients with chronic hepatitis B randomly allocating to three groups: (i) T6 group (n = 32) received a 26-week course of Talpha1 1.6 mg two times a week; (ii) T12 group (n = 34) received the same regimen as T6 group, but Talpha1 therapy extended for 52 weeks; (iii) T0 group (n = 32) served as a control and was followed up for 18 months without specific treatment. Stepwise logistic regression analysis showed that genotype (OR, 3.747; 95% CI, 1.066-13.170; P = 0.039), precore mutation (OR, 6.285; 95% CI, 1.874-21.086; P = 0.003) and Talpha-1 treatment (OR, 12.045; 95% CI, 2.220-65.354; P = 0.004) as independent factors associated with complete response. The complete response of Talpha-1 therapy was higher in patients with genotype B compared to patients with genotype C (52%vs 24%; P = 0.036) and in patients with precore mutation (64%vs 19%; P = 0.002). In conclusion, genotype, presence of precore mutation and Talpha-1 therapy were independent predictors to complete response. Genotype B, compared to genotype C, is associated with a higher response rate to T-alpha1 therapy.

Liposomal plasmid DNA encoding human thymosin alpha and interferon omega potently inhibits liver tumor growth in ICR mice

AIM

To evaluate the potential therapeutic effect of liposomal gene delivery, genes encoding for human thymosin alpha1 (Talpha1) and interferon omega1 were injected via the tail vein into mice bearing a Hep-A-22 liver tumor.

METHODS

The cDNA of human Talpha1 and interferon omega1 were obtained by synthesis or reverse transcription-polymerase chain reaction (RT-PCR), respectively. Eukaryotic expressing vectors pIRES2, encoding Talpha1 and/or interferon omega1, were constructed and injected with liposome via the tail vein into ICR mice bearing a Hep-A-22 tumor. The potency of tumor inhibition was evaluated when three treated groups were compared with the group receiving the empty vector. Apoptosis of tumor cells was investigated by analyzing DNA fragmentation.

RESULTS

Only the group treated with dual-gene plasmid reached an eligible level of tumor inhibition (43%). The difference in tumor weight was statistically significant between the Talpha1 gene or the interferon omega1 gene treated groups and the control (P<0.05), and highly significant between the dual-gene treated group and the control (P<0.01). DNA ladder was observed in the tumor cells from the purpose gene treated groups but not from the control.

CONCLUSION

The dual-gene plasmid-liposome complex showed more potent inhibition than the single gene constructs on the growth of Hep-A-22 tumor cells in mice, which may be attributed to indirect and additive induction of apoptosis in tumor cells by increased expression of Talpha1 and interferon omega1.

Immunomodulatory function of orally administered thymosin alpha1

OBJECTIVE

To investigate the immunological function of a yeast expression system for thymosin alpha1 (Talpha1).

METHODS

A constructed Talpha1 yeast expression system was used to investigate the immunological function of orally administered Talpha1. Dried yeast containing three different concentration of Talpha1 was fed to normal Balb/c mice and other Balb/c mice whose immunities were inhibited in advance by cyclophosphamide. Synthesized Talpha1 peptide was used as positive control and dried yeast with empty plasmid was used as negative control. CD4(+) and CD8(+) levels were detected by flow cytometry assay. TNF-alpha, IFN-gamma, IL-2, IL-6 and IL-10 levels were detected by liquid chip.

RESULTS

In normal Balb/c mice or immune inhibition Balb/c mice, CD8(+) levels were significantly increased. Especially in immune inhibition Balb/c mice, CD8(+) levels in synthesized Talpha1 group (18.77%+/-4.72%), small dose group (13.48%+/-6.17%) and large dose group (22.74%+/-1.09%) were significantly higher than that in empty yeast control group (7.49%+/-2.14%).

CONCLUSION

Orally administered Talpha1 has its certain immunomodulatory function.

Cytokine profile of peripheral blood mononuclear cells from patients with different outcomes of hepatitis C virus infection

SUMMARY

The relationship between the balance of helper T-cell type 1 (Th1) or type 2 (Th2) cytokines and the clinical course of hepatitis C virus (HCV) infection is unclear. We evaluated Th1 [interleukin (IL)-2, interferon-gamma (IFN-gamma)] and Th2 cytokine (IL-4, IL-10) and 2,5-oligoadenylate synthetase (OAS, an IFN-induced antiviral protein) production by peripheral blood mononuclear cells from 10 healthy anti-HCV-positive individuals (group A), 10 HCV-RNA-positive with persistently normal alanine aminotransferase (ALT) levels (group B), 10 HCV-RNA-positive with abnormal ALT (group C) and 10 uninfected healthy controls. IL-2 production was significantly increased in group B when compared with all the other groups. No difference was found for IFN-gamma. IL-4 was significantly higher in group C than in both group B (P = 0.0006) and controls (P = 0.004). Compared with controls, IL-10 was significantly decreased in group A (P = 0.013) and B (P = 0.004). The production of 2,5-OAS was significantly higher in group B than in A (P = 0.04) and in C (P = 0.004). Finally, in all HCV-RNA-positive patients, a significant correlation was found between ALT and both IL-2 (r = -0.78; P = 0.0008) and IL-4 (r = 0.75; P = 0.0008).

IN CONCLUSION

(i) subjects who cleared HCV showed a cytokine profile similar to controls; (ii) a preferential shift towards a Th1 profile seems associated with a more favourable clinical outcome in chronic hepatitis C; and (iii) a prevalent Th2 profile seems implicated in HCV pathogenesis and severity of liver disease.

Therapeutic modalities in hepatitis C: challenges and development

Our understanding of the pathogenicity of hepatitis C virus (HCV) is based on patients infected chronically for >20 years. The lack of a suitable animal model, the narrow host range of the virus, and the protracted onset of liver disease induced by HCV have hampered advances in treatment. In spite of these problems, we identified patient and viral characteristics that predict responses to current therapies, including HCV genotype, viral load, body weight, age, liver histology, co-infection with HIV and treatment adherence and tolerance. Interferon (IFN) alpha was the first therapy for chronic HCV infection. The combination of IFN plus ribavirin increases sustained virological response rates compared with IFN alone. Two pegylated IFNs have been developed and are widely approved for the treatment of chronic hepatitis C: peginterferon alpha-2a (40 KD), and pegylated IFN alpha-2b (12 KD). These products have reduced systemic clearance, prolonged half-lives and reduced antigenicity compared with conventional IFN. The reduced clearance results in sustained plasma levels of the drug and allows for once-weekly dosing. Pegylated IFN alpha-2b (12 KD) has a small, linear polyethylene glycol (PEG) moiety and has an intermediate duration of activity; peginterferon alpha-2a (40 KD) incorporates a large, branched-chain PEG moiety and has a longer half-life than both conventional IFN alpha and pegylated IFN alpha-2b (12 KD). The combination of a pegylated IFN plus ribavirin significantly increases sustained virological response rates compared with conventional IFN plus ribavirin in patients with chronic hepatitis C and is now recognized as the standard of care for these patients.

Thymalfasin for the treatment of chronic hepatitis B

Chronic hepatitis B virus infection is a serious problem because of its worldwide distribution and possible adverse chronic sequelae, such as cirrhosis and hepatocellular carcinoma. Chronic hepatitis B infection is a dynamic state of interactions between the virus, hepatocyte and host immune response. Interferon-alpha and direct antiviral agents, such as lamivudine (Epivir, GlaxoSmithKline), are effective in the therapy of chronic HBV infection but the efficacy is far from satisfactory. Thymalfasin (thymosin alpha1; Talpha1, Zadaxintrade mark, SciClone Pharmaceuticals, Inc.) is a 28-amino acid polypeptide produced synthetically but originally isolated from thymosin fraction 5, a bovine thymus extract containing a number of immunologically active peptides. In vitro studies have shown that Talpha1 can influence T-cell production and maturation, stimulate production of Th1 cytokines such as interferon-gamma and interleukin-2, and activate natural killer cell-mediated cytotoxicity. Seven randomized controlled studies on Talpha1 monotherapy in patients with chronic hepatitis B showed that 6 months treatment with Talpha1 (1.6 mg twice-weekly) resulted in a significantly higher sustained response rate than untreated controls. The benefits of Talpha1 therapy is usually not immediately apparent during therapy. There is a trend for complete virological response to increase or accumulate gradually after the end of thymosin therapy. The results of Talpha1 and interferon combination therapy in two open-label trials were also promising. In terms of the mechanisms of action, a combination of Talpha1 and nucleoside or nucleotide analogs is a logical approach in the control of chronic HBV infection and a randomized control study is ongoing.

Thymalfasin: an immune system enhancer for the treatment of liver disease

Thymalfasin (thymosin-alpha 1) is an immunomodulating agent able to enhance the Th1 immune response. It has been evaluated for its immunomodulatory activities and related therapeutic potential in several diseases, including chronic hepatitis B and C, AIDS, primary immunodeficiency diseases, depressed response to vaccination and cancer. The basis for effectiveness in these conditions is primarily through modulation of immunological responsiveness, as thymalfasin has been shown to have beneficial effects on numerous immune system parameters and to increase T-cell differentiation and maturation. Thymalfasin is responsible for reconstitution of immune function when thymic tissue is given back to thymectomized animals. In addition, thymalfasin has been shown to have efficacy in multiple experimental models of immune dysfunction, mainly, infectious diseases such as hepatitis (woodchuck) and influenza (mouse), and cancer such as melanoma (mouse) and colorectal carcinoma (rat) where thymalfasin has shown antitumor effects.

New antiviral therapies for hepatitis C

Hepatitis C affects 170 million people worldwide and is the leading indication for liver transplantation. However, despite this high prevalence and burden of disease, current treatment regimens necessitate long durations of therapy, are often poorly tolerated and have suboptimal rates of sustained virologic response. Therefore, much attention has been directed at the development of new therapeutic agents against specific viral targets. This article reviews modifications of current therapies, outlines the viral life cycle and focuses on novel therapeutic agents currently being studied.

In vitro effect of indomethacin and interferon-α on Th1 and Th2 cytokine synthesis in patients with chronic hepatitis C

Current evidences suggest that non-steroidal anti-inflammatory drugs could enhance the antiviral activity of interferon-alpha in chronic HCV infection. In this study, we investigated the effect of indomethacin, a non-steroidal anti-inflammatory drug, and interferon-alpha on cytokine production by peripheral blood mononuclear cells from 12 untreated patients with chronic hepatitis C. We evaluated the effect of incubation with indomethacin, interferon-alpha or both on synthesis of Th1- (interleukin-2, interferon-gamma) and Th2-associated cytokines (interleukin-4, interleukin-10), and of the antiviral protein 2',5'-oligoadenylate synthetase. Interferon-alpha induced a significant increase in production of interleukin-2. Smaller increases were also seen in the presence of indomethacin, while incubation with both indomethacin and interferon-alpha leads to a synergistic effect. Incubation with indomethacin decreased both interleukin-4 and interleukin-10, whereas interferon-alpha increased these cytokines. The addition of indomethacin to interferon-alpha significantly reversed this interferon-induced increase. Finally, both indomethacin and the association interferon-alpha plus indomethacin determined a significant increase in 2',5'-oligoadenylate synthetase production compared to both baseline and interferon-alpha alone. In conclusion, indomethacin was able to enhance the antiviral activity of interferon-alpha and to modulate the interferon-induced Th1 and Th2 cytokine response by increasing the Th1-response, fundamental for sustained clearance of HCV, and by decreasing the Th-2 type response, associated with HCV persistence.

Thymosin-alpha 1 plus interferon-alpha for naive patients with chronic hepatitis C: results of a randomized controlled pilot trial

In this pilot study, we evaluated the efficacy of interferon-alpha (IFN) plus Thymosin-alpha 1 (TA1) to that of IFN alone in naive patients with chronic hepatitis C. Twenty-two patients were randomized to receive interferon-alpha 2b (3 million units three times a week) plus thymosin-alpha l (900 microg/m2 body surface area) and 19 received interferon-alpha 2b alone at the same dose. Patients were treated for 6 months and followed up for another 6 months. Biochemical (alanine aminotransferase values) and virological (hepatitis C virus-RNA) responses to treatment were determined. Combination treatment showed significantly higher efficacy than monotherapy in achieving virological end-of-treatment response (P = 0.03). At 6-month follow up, the sustained biochemical and virological response was not different between the two groups. Our results indicate that the immune modulator TA1 may enhance the end-of-treatment response in naive patients with chronic hepatitis C. Higher doses and/ore more prolonged courses as well as the association with new interferon formulation such as pegylated interferons could improve the sustained response rates to this treatment.

Combinatorial immunotherapies for infectious diseases

Combating pathogenic organisms by combinatorial approaches involving appropriate immune response molecules and antimicrobial drugs represents a progessively more apparent and successful therapeutic paradigm for the treatment of acute and chronic persistent infectious diseases. This review explores areas of current innovation and provides an update of the present state of knowledge concerning combination of chemotherapy with several immune-based interventions in infections. In the future, a better understanding of microbial immune modulation and evasion may continue to open new avenues of inquiry and carefully targeted application of adjunctive immunotherapies.

Combination therapy in the treatment of chronic viral hepatitis and prevention of hepatocellular carcinoma

Treatment of chronic hepatitis B and C viruses (HBV and HCV) is still disappointing, and both are the major causes of liver cirrhosis and hepatocarcinoma. Interferon and lamivudine are the registered drugs for chronic HBV but are scarcely effective on HBeAg-negative patients, and resistance due to virus mutation is the rule with lamivudine. Interferon and ribavirine represent the standard treatment for chronic HCV but less than the half of the infected population is eligible for this treatment and less of the half of treated patients will experience a sustained response. No single new drug to date has shown the potential to overcome this dismal picture. Combined strategies are thus the currently most available approach to improve the response rate of chronic HBV and HCV infection, with a subsequent decrease in the number of patients developing hepatocellular carcinoma (HCC). Combination of thymosin alpha 1 with interferon or antiviral agents is currently the most promising option, but nontoxic immunomodulants, such as oral MIMP, should be explored. This review focuses on the difficulties with current therapy and the rationale for use of combination therapy with thymosin alpha 1 for both HBV and HCV therapies.

New therapies on the horizon for hepatitis C: are we close?

A myriad of new therapies for treating hepatitis C are in various stages of preclinical and clinical development. As reviewed here, these include nucleic acid-based approaches (antisense and ribozymes), small molecule inhibitors of essential hepatitis C virus (HCV)-encoded enzymes (protease, helicase, and polymerase), immune modulation, and immunotherapy. As more details of the HCV lifecycle are elucidated, new targets and approaches will be discovered. Drug development is difficult, expensive, and always agonizingly slow for patients in need and their physicians. Nonetheless, a broad effort has been mounted for HCV, and substantial progress has been achieved. The prospects for new HCV treatments are bright.

Thymosin alpha1 accelerates restoration of T cell-mediated neutralizing antibody response in immunocompromised hosts

Thymosin alpha1 is a biological response modifier that has been used clinically for the treatment of chronic hepatitis B viral infection. Both immunomodulatory and immediate intracellular mechanisms have been postulated to explain the effect of thymosin alpha1 on hepatocytes infected with hepatitis B virus (HBV). Here, we established a new animal model and the related suitable conditions to access the thymosin activity by means of measuring the production of neutralizing antibody against hepatitis B surface antigen (HBsAg). We proved that chemically synthesized thymosin alpha1 restored the T cell-mediated antibody production following its suppression in mice by 5-fluorouracil (5-FU), and found that thymosin alpha1 showed activity at a low dose of 30 microg/kg. Further studies utilizing the flowcytometric analysis showed that thymosin alpha1 at this dose accelerated the replenishment and maturation of thymocytes while the expression of Smoothened (Smo) of the Hedgehog (Hh)-signaling in CD4-CD8- thymocytes, the potent negative regulator of proliferative responses, was not affected. The restoration of some of the defects in the host defense systems may facilitate elimination of infectious agents, and the present study provides a novel model to define the restoration of T cell-mediated immune responses to hepatitis B virus in vivo.