Reciprocal interference between insulin and interferon-alpha signaling in hepatic cells: a vicious circle of clinical significance?

Interferon Upregulation Associates with Insulin Resistance in Humans

In humans, insulin resistance is a physiological response to infections developed to supply sufficient energy to the activated immune system. This metabolic adaptation facilitates the immune response but usually persists after the recovery period of the infection and predisposes the hosts to type 2 diabetes and vascular injury. In patients with diabetes, superimposed insulin resistance worsens metabolic control and promotes diabetic ketoacidosis. Pathogenic mechanisms underlying insulin resistance during microbial invasions remain to be fully defined. However, interferons cause insulin resistance in healthy subjects and other population groups, and their production is increased during infections, suggesting that this group of molecules may contribute to reduced insulin sensitivity. In agreement with this notion, gene expression profiles (transcriptomes) from patients with insulin resistance show a robust overexpression of interferon- stimulated genes (interferon signature). In addition, serum levels of interferon and surrogates for interferon activity are elevated in patients with insulin resistance. Circulating levels of interferon- γ-inducible protein-10, neopterin, and apolipoprotein L1 correlate with insulin resistance manifestations, such as hypertriglyceridemia, reduced HDL-c, visceral fat, and homeostasis model assessment-insulin resistance. Furthermore, interferon downregulation improves insulin resistance. Antimalarials such as hydroxychloroquine reduce interferon production and improve insulin resistance, reducing the risk for type 2 diabetes and cardiovascular disease. In addition, diverse clinical conditions that feature interferon upregulation are associated with insulin resistance, suggesting that interferon may be a common factor promoting this adaptive response. Among these conditions are systemic lupus erythematosus, sarcoidosis, and infections with severe acute respiratory syndrome-coronavirus-2, human immunodeficiency virus, hepatitis C virus, and Mycobacterium tuberculosis.

Altered hepatic metabolic landscape and insulin sensitivity in response to pulmonary tuberculosis

Chronic inflammation triggers development of metabolic disease, and pulmonary tuberculosis (TB) generates chronic systemic inflammation. Whether TB induced-inflammation impacts metabolic organs and leads to metabolic disorder is ill defined. The liver is the master regulator of metabolism and to determine the impact of pulmonary TB on this organ we undertook an unbiased mRNA and protein analyses of the liver in mice with TB and reanalysed published data on human disease. Pulmonary TB led to upregulation of genes in the liver related to immune signalling and downregulation of genes encoding metabolic processes. In liver, IFN signalling pathway genes were upregulated and this was reflected in increased biochemical evidence of IFN signalling, including nuclear location of phosphorylated Stat-1 in hepatocytes. The liver also exhibited reduced expression of genes encoding the gluconeogenesis rate-limiting enzymes Pck1 and G6pc. Phosphorylation of CREB, a transcription factor controlling gluconeogenesis was drastically reduced in the livers of mice with pulmonary TB as was phosphorylation of other glucose metabolism-related kinases, including GSK3a, AMPK, and p42. In support of the upregulated IFN signalling being linked to the downregulated metabolic functions in the liver, we found suppression of gluconeogenic gene expression and reduced CREB phosphorylation in hepatocyte cell lines treated with interferons. The impact of reduced gluconeogenic gene expression in the liver was seen when infected mice were less able to convert pyruvate, a gluconeogenesis substrate, to the same extent as uninfected mice. Infected mice also showed evidence of reduced systemic and hepatic insulin sensitivity. Similarly, in humans with TB, we found that changes in a metabolite-based signature of insulin resistance correlates temporally with successful treatment of active TB and with progression to active TB following exposure. These data support the hypothesis that TB drives interferon-mediated alteration of hepatic metabolism resulting in reduced gluconeogenesis and drives systemic reduction of insulin sensitivity.

Self-Nucleic Acid Sensing: A Novel Crucial Pathway Involved in Obesity-Mediated Metaflammation and Metabolic Syndrome

Obesity and overweight are a global health problem affecting almost one third of the world population. There are multiple complications associated with obesity including metabolic syndrome that commonly lead to development of type II diabetes and non-alcoholic fatty liver disease. The development of metabolic syndrome and severe complications associated with obesity is attributed to the chronic low-grade inflammation that occurs in metabolic tissues such as the liver and the white adipose tissue. In recent years, nucleic acids (mostly DNA), which accumulate systemically in obese individuals, were shown to aberrantly activate innate immune responses and thus to contribute to metabolic tissue inflammation. This minireview will focus on (i) the main sources and forms of nucleic acids that accumulate during obesity, (ii) the sensing pathways required for their detection, and (iii) the key cellular players involved in this process. Fully elucidating the role of nucleic acids in the induction of inflammation induced by obesity would promote the identification of new and long-awaited therapeutic approaches to limit obesity-mediated complications.

Type I interferon sensing unlocks dormant adipocyte inflammatory potential

White adipose tissue inflammation, in part via myeloid cell contribution, is central to obesity pathogenesis. Mechanisms regulating adipocyte inflammatory potential and consequent impact of such inflammation in disease pathogenesis remain poorly defined. We show that activation of the type I interferon (IFN)/IFNα receptor (IFNAR) axis amplifies adipocyte inflammatory vigor and uncovers dormant gene expression patterns resembling inflammatory myeloid cells. IFNβ-sensing promotes adipocyte glycolysis, while glycolysis inhibition impeded IFNβ-driven intra-adipocyte inflammation. Obesity-driven induction of the type I IFN axis and activation of adipocyte IFNAR signaling contributes to obesity-associated pathogenesis in mice. Notably, IFNβ effects are conserved in human adipocytes and detection of the type I IFN/IFNAR axis-associated signatures positively correlates with obesity-driven metabolic derangements in humans. Collectively, our findings reveal a capacity for the type I IFN/IFNAR axis to regulate unifying inflammatory features in both myeloid cells and adipocytes and hint at an underappreciated contribution of adipocyte inflammation in disease pathogenesis.

White adipose inflammation can occur in obesity and is at least in part mediated by inflammatory immune cells. Here the authors show that the Type I Interferon/Interferon alpha-beta receptor axis promotes an inflammatory, glycolysis associated adipocyte phenotype.

Comprehensive evaluation of effects and safety of statin on the progression of liver cirrhosis: a systematic review and meta-analysis

Background

Statin has been more and more widely used in chronic liver disease, however, existed studies have attained contradictory results. According to the present study, we aimed to test the efficacy and safety of statin via a meta-analysis.

Methods

Different databases were searched for full-text publication based on inclusion and exclusion criteria. For data-pooling, fixed-effect model was applied if heterogeneity wasn’t detected. Otherwise, random-effect model was adopted. Heterogeneity was detected by I squire (I²) test. All results of analysis were illustrated as forest plots. Publication bias was assessed using the Begg’s adjusted rank correlation test. Standard mean difference (SMD) was calculated in continuous variables. Pooled hazard ratio or odds ratio was calculated in catergorical variables.

Results

Seventeen clinical studies were finally included. Hepatic portal hemodynamic parameters were improved in statin users for a short-term response. For a long-term follow-up, statin treatment surprisingly decreased mortality rate (HR = 0.782, 95% CI: 0.718–0.846, I² > 50%) and lower the occurrence of hepatocellular carcinoma (HR = 0.75, 95% CI: 0.64–0.86, I² > 50%) in liver cirrhosis. Statin seemed not to decrease the risk of esophageal variceal bleeding and spontaneous bacterial peritonitis. However, statin was proved to decrease the risk of hepatic encephalopathy and ascites. Incidence of drug related adverse events didn’t increase in statin users. Dose-dependent effects of statin on hepatocellular carcinoma development, decompensated cirrhosis events occurrence, and liver cirrhosis progression.

Conclusion

Statin influenced parameters of hepatic portal vessel pressure in short-term treatment. Prognosis of liver cirrhosis benefited from statin treatment in long term follow-up. The efficacy and safety of statin in liver cirrhosis treatment is confirmed. To date, similar study is hardly seen before.

Inflammation and Immunity: From an Adipocyte's Perspective

Comprehension of adipocyte function has evolved beyond a long-held belief of their inert nature, as simple energy storing and releasing cells. Adipocytes, including white, brown, and beige, are capable mediators of global metabolic health, but their intersection with inflammation is a budding field of exploration. Evidence hints at a reciprocal relationship adipocytes share with immune cells. Adipocyte's capacity to behave in an "immune-like" manner and ability to sense inflammatory cues that subsequently alter core adipocyte function might play an important role in shaping immune responses. Clarifying this intricate relationship could uncover previously underappreciated contribution of adipocytes to inflammation-driven human health and disease. In this review, we highlight the potential of largely underappreciated adipocyte "immune-like" function and how it may contribute to inflammation, immunity, and pathology of various diseases.

Do Type I Interferons Link Systemic Autoimmunities and Metabolic Syndrome in a Pathogenetic Continuum?

The central pathogenetic role of type I interferons (IFNs) in several systemic autoimmune diseases is well established. Recent studies have also discovered a similar crucial role of type I IFNs in different components of metabolic disorders. Self nucleic acid-driven Toll-like receptor (TLR) activation in plasmacytoid dendritic cells (pDCs) and type I IFN induction appear to be the key initiating events shared by most of these autoimmune and metabolic diseases. Further strengthening this link, many patients with systemic autoimmunities also present with metabolic disorders. This concurrence of autoimmunities and metabolic disorders may be explained by a single pathogenetic continuum, and suggests shared targets for potential new therapies.

Type I Interferons Interfere with Liver Glucose Metabolism

The specific immunological components linking metabolic stresses to liver inflammation and systemic metabolic pathologies in obesity are not entirely known. A recent study (Ghazarian et al., 2017) reveals that obesity-induced type I interferon signaling drives the accumulation and activation of intrahepatic CD8⁺ T cells, leading to systemic metabolic deterioration.

Type I Interferon Responses Drive Intrahepatic T cells to Promote Metabolic Syndrome

Obesity-related insulin resistance is driven by low-grade chronic inflammation of metabolic tissues. In the liver, non-alcoholic fatty liver disease (NAFLD) is associated with hepatic insulin resistance and systemic glucose dysregulation. However, the immunological factors supporting these processes are poorly understood. We found that the liver accumulates pathogenic CD8+ T cell subsets which control hepatic insulin sensitivity and gluconeogenesis during diet-induced obesity in mice. In a cohort of human patients, CD8+ T cells represent a dominant intrahepatic immune cell population which links to glucose dysregulation. Accumulation and activation of these cells are largely supported by type I interferon (IFN-I) responses in the liver. Livers from obese mice upregulate critical interferon regulatory factors (IRFs), interferon stimulatory genes (ISGs), and IFNα protein, while IFNαR1-/- mice, or CD8-specific IFNαR1-/- chimeric mice are protected from disease. IFNαR1 inhibitors improve metabolic parameters in mice, while CD8+ T cells and IFN-I responses correlate with NAFLD activity in human patients. Thus, IFN-I responses represent a central immunological axis that governs intrahepatic T cell pathogenicity during metabolic disease.

Adipose Recruitment and Activation of Plasmacytoid Dendritic Cells Fuel Metaflammation

In obese individuals, visceral adipose tissue (VAT) is the seat of chronic low-grade inflammation (metaflammation), but the mechanistic link between increased adiposity and metaflammation largely remains unclear. In obese individuals, deregulation of a specific adipokine, chemerin, contributes to innate initiation of metaflammation by recruiting circulating plasmacytoid dendritic cells (pDCs) into VAT through chemokine-like receptor 1 (CMKLR1). Adipose tissue-derived high-mobility group B1 (HMGB1) protein activates Toll-like receptor 9 (TLR9) in the adipose-recruited pDCs by transporting extracellular DNA through receptor for advanced glycation end products (RAGE) and induces production of type I interferons (IFNs). Type I IFNs in turn help in proinflammatory polarization of adipose-resident macrophages. IFN signature gene expression in VAT correlates with both adipose tissue and systemic insulin resistance (IR) in obese individuals, which is represented by ADIPO-IR and HOMA2-IR, respectively, and defines two subgroups with different susceptibility to IR. Thus, this study reveals a pathway that drives adipose tissue inflammation and consequent IR in obesity.

Type I Interferon-Mediated Induction of Antiviral Genes and Proteins Fails to Protect Cells from the Cytopathic Effects of Sendai Virus Infection

Sendai virus (SeV), a murine paramyxovirus, has been used to study the induction of type I interferon (IFN) subtypes in robust quantities. Few studies have measured whether the IFN that SeV induces actually fulfills its intended purpose of interfering with virus-mediated effects in the cells in which it is produced. We determined the effects of IFN on SeV-mediated cytopathic effects (CPE) and the ability of IFN to protect against virus infection. SeV-induced biologically active IFN resulted in Jak/STAT activation and the production of a number of interferon-stimulated genes (ISGs). However, these responses did not inhibit SeV replication or CPE. This observation was not due to SeV effects on canonical IFN signaling. Furthermore, pretreating cells with type I IFN and establishing an antiviral state before infection did not mediate SeV effects. Therefore, the induction of canonical IFN signaling pathways and ISGs does not always confer protection against the IFN-inducing virus. Because type I IFNs are approved to treat various infections, our findings suggest that typical markers of IFN activity may not be indicative of a protective antiviral response and should not be used alone to determine whether an antiviral state against a particular virus is achieved.

Characterisation of the cytokine milieu associated with the up-regulation of IL-6 and suppressor of cytokine 3 in chronic hepatitis C treatment non-responders

BACKGROUND & AIMS

In chronic hepatitis C virus infection (CHC), expression of suppressor of cytokine signalling-3 (SOCS3) has been shown to be associated with obesity and non-response to antiviral therapy. In this study, we aimed to determine the effect of SOCS3 induction on the cytokine response in patients receiving Pegylated interferon (PegIFN) and ribavirin (RBV) therapy.

METHODS

Peripheral blood mononuclear cells (PBMC) collected at baseline and at 12 weeks from CHC patients receiving PegIFN/RBV therapy were examined for mRNA and protein SOCS3 expression. Immunological assays were employed to examine cytokine production.

RESULTS

There was increased expression of SOCS3 in PBMC of non-responders at week 12 of therapy, when compared to treatment responders (P = 0.0001). The expression of SOCS3 correlated with body mass index (BMI) (r = 0.54; P = 0.01). Patients with low SOCS3 expression at week 12 of therapy had lower HCV-specific IFN-γ production in enzyme-linked immunosorbent spot (ELISpot) assays (P = 0.01), and reduced ex-vivo production of the anti-HCV effector cytokines interleukin (IL)-2 and tumour necrosis factor (TNF)-α(P = 0.01 and P = 0.04 respectively). Analysis of serum cytokine levels revealed higher levels of IL-6 at week 12 in the high SOCS3 expression group (P = 0.02) while IL-6 levels correlated with SOCS3 expression in the entire cohort (P = 0.04). Ex-vivo studies confirmed that IL-6 induced SOCS3, and neutralisation of IL-6 reduced levels of SOCS3.

CONCLUSION

In subjects with increased BMI and non-response to antiviral therapy, the IL-6/SOCS3 axis appears to play a crucial role in altering the anti-HCV-cytokine response associated with antiviral therapy.

Diabetes and Hepatitis C: A Two-Way Association

Diabetes and hepatitis C infection are both prevalent diseases worldwide, and are associated with increased morbidity and mortality. Most studies, but not all, have shown that patients with chronic hepatitis C are more prone to develop type 2 diabetes (T2D) compared to healthy controls, as well as when compared to patients with other liver diseases, including hepatitis B. Furthermore, epidemiological studies have revealed that patients with T2D may also be at higher risk for worse outcomes of their hepatitis C infection, including reduced rate of sustained virological response, progression to fibrosis and cirrhosis, and higher risk for development of hepatocellular carcinoma. Moreover, hepatitis C infection and mainly its treatment, interferon α, can trigger the development of type 1 diabetes. In this review, we discuss the existing data on this two-way association between diabetes and hepatitis C infection with emphasis on possible mechanisms. It remains to be determined whether the new curative therapies for chronic hepatitis C will improve outcomes in diabetic hepatitis C patients, and conversely whether treatment with Metformin will reduce complications from hepatitis C virus infection. We propose an algorithm for diabetes screening and follow-up in hepatitis C patients.

FoxO3a nuclear localization and its association with β-catenin and Smads in IFN-α-treated hepatocellular carcinoma cell lines

Interferon-α2b (IFN-α2b) reduces proliferation and increases apoptosis in hepatocellular carcinoma cells by decreasing β-catenin/TCF4/Smads interaction. Forkhead box O-class 3a (FoxO3a) participates in proliferation and apoptosis and interacts with β-catenin and Smads. FoxO3a is inhibited by Akt, IκB kinase β (IKKβ), and extracellular-signal-regulated kinase (Erk), which promote FoxO3a sequestration in the cytosol, and accumulates in the nucleus upon phosphorylation by c-Jun N-terminal kinase (JNK) and p38 mitogen-activated kinase (p38 MAPK). We analyzed FoxO3a subcellular localization, the participating kinases, FoxO3a/β-catenin/Smads association, and FoxO3a target gene expression in IFN-α2b-stimulated HepG2/C3A and Huh7 cells. Total FoxO3a and Akt-phosphorylated FoxO3a levels decreased in the cytosol, whereas total FoxO3a levels increased in the nucleus upon IFN-α2b stimulus. IFN-α2b reduced Akt, IKKβ, and Erk activation, and increased JNK and p38 MAPK activation. p38 MAPK inhibition blocked IFN-α2b-induced FoxO3a nuclear localization. IFN-α2b enhanced FoxO3a association with β-catenin and Smad2/3/7. Two-step coimmunoprecipitation experiments suggest that these proteins coexist in the same complex. The expression of several FoxO3a target genes increased with IFN-α2b. FoxO3a knockdown prevented the induction of these genes, suggesting that FoxO3a acts as mediator of IFN-α2b action. Results suggest a β-catenin/Smads switch from TCF4 to FoxO3a. Such events would contribute to the IFN-α2b-mediated effects on cellular proliferation and apoptosis. These results demonstrate new mechanisms for IFN-α action, showing the importance of its application in antitumorigenic therapies.

Homeostasis model assessment of insulin resistance does not seem to predict response to telaprevir in chronic hepatitis C in the REALIZE trial

Baseline homeostasis model assessment-estimated insulin resistance (HOMA-IR), a marker for insulin resistance, has been associated with poor virologic response to peginterferon alpha/ribavirin (PR) in chronic hepatitis C. We evaluated the association between baseline HOMA-IR and pretreatment factors on sustained virologic response (SVR) to telaprevir (TVR) in genotype 1 patients with hepatitis C and prior peginterferon/ribavirin (PR) treatment failure. Patients were randomized to 12 weeks of TVR (750 mg q8h) plus peginterferon (180 μg/week) and ribavirin (1,000-1,200 mg/day) (with or without a 4-week lead-in) followed by PR, or PR alone (PR48), for 48 weeks. Univariate and multiple logistic regression analyses explored the prognostic significance of baseline HOMA-IR alone and adjusted for other pretreatment factors and SVR. The TVR arms were pooled for the purposes of this analysis. In all, 662 patients were randomized; 578 had baseline HOMA-IR and other prognostic data and were included in this analysis. Median baseline HOMA-IR was 2.6 (interquartile range [IQR] 1.7-4.3); 207 (36%), 206 (36%), and 165 (29%) patients had baseline HOMA-IR <2, 2 to <4, and ≥ 4, respectively. Male gender, higher body mass index, triglycerides, gamma-glutamyl transpeptidase, maximum alanine aminotransferase/aspartate aminotransferase, and fibrosis stage were associated with higher baseline HOMA-IR. Baseline HOMA-IR was associated with SVR in univariate analysis, but not after adjustment for other baseline prognostic factors (TVR: OR = 0.95, 95% confidence interval [CI]: 0.71,1.29; PR48: 0.60; 95% CI: 0.25,1.43).

CONCLUSION

In patients with prior PR treatment failure, baseline HOMA-IR correlated with SVR in univariate but not multivariate analyses, suggesting other factors have a more direct causal relationship with virologic response to TVR-based therapy than HOMA-IR.

Metabolic factors and chronic hepatitis C: a complex interplay

In the last years, several lines of evidence showed how metabolic factors may influence the natural history of patients with chronic hepatitis C. Chronic HCV infection is able to perturb the metabolic homeostasis of the host, in a context of complex interactions where pre-existent metabolic status and genetic background play an important role, allowing us to state that HCV infection is a systemic disease. In this review, we discuss the most recent lines of evidence on the main metabolic factors that are known to be associated with CHC, namely, insulin resistance/type 2 diabetes, steatosis, visceral obesity, atherosclerosis, vitamin D, menopause, fructose and coffee intake, lipoproteins, methylenetetrahydrofolate reductase status, and hyperuricaemia. In particular, we focus on the pathophysiological mechanisms underlying the correlation between HCV infection and metabolic disorders, the impact of metabolic factors on the progression of liver and non-liver-related diseases, and, on the contrary, the possible influence of chronic HCV infection on metabolic features. In this setting, the importance of a multifaceted evaluation of CHC patients and a prompt correction of modifiable metabolic risk factors should be emphasized.

Association of the IL28B genotype with insulin resistance in patients with chronic hepatitis C

BACKGROUND & AIMS

Insulin resistance, fibrosis and steatosis are established predictors of response to peg-interferon/ribavirin therapy in chronic hepatitis C (CHC). Several host genetic polymorphisms (IL28B, PNPLA3) modify treatment-outcome, the degree of steatosis or fibrosis. The aim of our study was to evaluate the role of these polymorphisms on insulin resistance (IR) in treatment-naïve patients with chronic hepatitis C.

METHODS

Two hundred and two non-diabetic CHC patients (GT1: 181, GT4: 21; m = 126, f = 76) undergoing liver biopsy in two tertiary academic centers were studied. The SNPs rs12979860 (IL28B) and rs738409 (PNPLA3) were investigated by RT-PCR. HOMA-IR, BMI, stage of fibrosis, extent of steatosis, and genetic data were analyzed.

RESULTS

Insulin resistance (HOMA-IR ≥ 3.0) was associated with rs12979860 genotype, presence of advanced fibrosis, and higher BMI. HOMA-IR in CC and in TC/TT was 2.08 ± 1.61 (mean ± SD) and 2.94 ± 2.89 (p=0.041), respectively. HOMA-IR was higher in advanced than in mild fibrosis (F3-4: 3.92 ± 3.15; F0-2: 2.38 ± 2.38; p=0.004). The percentage of steatotic hepatocytes was higher in patients with advanced fibrosis (21.3 ± 21.5 vs. 9.1 ± 14.2; p<0.001), HOMA-IR ≥ 3.0 (17.7 ± 17.8 vs. 8.8 ± 15.4%; p<0.001), and BMI > 25.0 kg/m(2) (14.7 ± 17.0 vs. 9.1 ± 16.1; p<0.001). The rs738409 GG genotype was associated with advanced fibrosis and steatosis, but not with HOMA-IR. Multivariable logistic regression identified advanced fibrosis (OR: 2.820, 95% CI: 1.344-5.917; p = 0.006) and the IL28B genotype non-CC (OR: 3.000, 1.348-6.676; p = 0.007) as independent risk factors for insulin resistance.

CONCLUSIONS

Insulin resistance is more common in carriers of the T allele of SNP rs12979860 than in CC homozygotes and may partly explain the poor outcome of peginterferon/ribavirin therapy in these patients.

Protein-tyrosine phosphatases are involved in interferon resistance associated with insulin resistance in HepG2 cells and obese mice

Insulin resistance is a risk factor for non-response to interferon/ribavirin therapy in patients with chronic hepatitis C. The aim of this study was to determine the role played by protein-tyrosine phosphatases (PTPs) in the absence of interferon-α (IFNα) response associated with insulin resistance. We induced insulin resistance by silencing IRS-2 or by treating HepG2 cells with tumor necrosis factor-α (TNFα) and analyzed insulin response by evaluating Akt phosphorylation and IFNα response by measuring Stat-1 tyrosine phosphorylation and 2',5'-oligoadenylate synthase and myxovirus resistance gene expression. The response to IFNα was also measured in insulin-resistant obese mice (high fat diet and ob/ob mice) untreated and treated with metformin. Silencing IRS-2 mRNA induces insulin resistance and inhibits IFNα response. Likewise, TNFα suppresses insulin and IFNα response. Treatment of cells with pervanadate and knocking down PTP-1B restores insulin and IFNα response. Both silencing IRS-2 and TNFα treatment increase PTP and PTP-1B activity. Metformin inhibits PTP and improves IFNα response in insulin-resistant cells. Insulin-resistant ob/ob mice have increased PTP-1B gene expression and activity in the liver and do not respond to IFNα administration. Treatment with metformin improves this response. In HepG2 cells, insulin resistance provokes IFNα resistance, which is associated with an increased PTP-1B activity in the liver. Inhibition of PTP-1B activity with pervanadate and metformin or knocking down PTP-1B reestablishes IFNα response. Likewise, metformin decreases PTP-1B activity and improves response to IFNα in insulin-resistant obese mice. The use of PTP-1B inhibitors may improve the response to IFNα/ribavirin therapy.