Systemic lupus erythematosus (SLE) is an autoimmune disease with a complex etiology. Various genetic factors are associated with susceptibility to developing SLE and contribute to its onset and progression. Different single-nucleotide polymorphisms (SNPs) have been associated with SLE in several populations. The rs12979860 SNP in interferon lambda 3/4 (IFNλ3/4) is significantly associated with SLE susceptibility in patients negative for nephritis in Taiwanese people, and interferon-stimulated genes (ISGs) are differentially expressed in normal liver by the rs12979860 genotype. This study aimed to investigate whether rs12979860 is associated with the presence of SLE and lupus nephritis in Mexican individuals as well as with the expression of several ISGs in SLE patients. In total, 439 SLE patients and 358 healthy donors were genotyped for rs12979860 using real-time PCR, and allelic discrimination plots were constructed. Additionally, peripheral blood mononuclear cells (PBMCs) were isolated from the venous blood of SLE patients by centrifugation (n = 78). The mRNA levels of 2'-5'-oligoadenylate synthetase like (OASL), myxovirus resistance 1 (MX1), 2'5'-oligoadenylate synthetase 1 (OAS1), interferon-stimulated gene 15 (ISG15) and lymphocyte antigen 6 complex, locus E (LY6E) were determined using real-time PCR. The distributions of rs12979860 genotypes and allele frequencies were compared between SLE patients and healthy donors; case-control analysis revealed that rs12979860 was not associated with SLE susceptibility (OR 1.18, 95% CI 0.97-1.45, p = 0.08) or with the risk for lupus nephritis (OR 0.913, 95% CI 0.590-1.411, p = 0.682). However, OASL expression levels in PBMCs were significantly different between rs12979860 genotypes in SLE patients: median OASL mRNA levels were significantly higher in patients carrying the CC genotype (197.10, IQR 71.10-411.17) than in those with CT/TT genotypes (173.75, IQR 58.80-278.75, p = 0.016). Our results suggest that the SNP rs12979860 does not play a relevant role in susceptibility to SLE in Mexican individuals. However, IFNλ3/4 genotypes appear to be associated with OASL expression in PBMCs from patients with SLE.

Keywords: interferon-stimulated genes; interferons lambda; oligoadenylate sinthetase-like; rs12979860 SNP; systemic lupus erythematosus.

Interferon lambda 3 (IFNL3, previously called IL-28B) is a cytokine with effects against viral and bacterial pathogens. We aimed to analyze the IFNL3 rs12980275 SNP in patients who underwent major surgery, in order to establish its relationship with susceptibility to septic shock and septic shock-related death in these patients. We performed a case-control study on 376 patients to establish the association between IFNL3 rs12980275 SNP and the susceptibility to develop septic shock. Besides, we performed a longitudinal study among 172 septic shock patients using survival analysis with one censoring point of 28-days mortality. The IFNL3 rs12980275 polymorphism was genotyped by Agena Bioscience's MassARRAY platform. IFNL3 rs12980275 polymorphism was not associated with higher susceptibility to infection and septic shock development. Regarding survival analysis, the Kaplan-Meier analysis showed that patients with IFNL3 rs12980275 AA genotype had higher survival than patients with GG genotype (p = 0.003). The Cox regression analysis adjusted by the most relevant clinical and epidemiological characteristics showed that the GG genotype (recessive model) and the presence of the G allele (additive model) were associated with higher risk of death [adjusted hazard ratio (aHR) = 2.15, p = 0.034; aHR = 1.50, p = 0.030, respectively]. In conclusion, IFNL3 rs12980275 polymorphism was associated with septic shock-related death in patients who underwent major surgery. The A allele was linked to protection, and the G allele was associated with an increased risk of death. This is a first preliminary study that suggests for the first time a role of IFNL3 polymorphisms in the prognosis of septic shock.

Keywords: IFNL3; SNP; major surgery; rs12980275; sepsis; septic shock; survival.

BACKGROUND

Genetic variation near the interferon lambda 3 (IFNL3) is known to be associated with response to pegylated interferon (pegIFN) and ribavirin combination therapy in patients with chronic hepatitis C virus (HCV) infection which is often accompanied by hepatic steatosis.

OBJECTIVE

We examined whether this genetic variation is associated with host lipids and treatment response.

METHODS

A total of 101 Japanese patients who had underwent liver biopsy before treatment with pegIFN and ribavirin for HCV genotype 1b infection were retrospectively analyzed for association between IFNL3 genotypes (rs8099917) and clinical factors including histopathological features of the liver. The presence of >5% steatosis in the liver specimen was defined as hepatic steatosis.

RESULTS

Forty patients (40%) had liver steatosis before therapy. Patients with IFNL3 minor genotype (non-TT) showed lower low-density lipoprotein cholesterol level (p=0.0045), higher γ-glutamyl transpeptidase level (p=0.0003) and higher prevalence of hepatic steatosis (p=0.0002). Advanced fibrosis [odds ratio (OR) 4.63, p=0.03] and IFNL3 major genotype (OR 0.13, p=0.001) were 2 independent factors for determining the presence of hepatic steatosis. Among the factors associated with sustained virological response, IFNL3 genotype was the most significant predictor, as per multivariate analysis.

CONCLUSIONS

Our results confirmed that IFNL3 genotype is associated with hepatic steatosis as well as IFN response.

Host single nucleotide polymorphisms (SNPs) in different genes can play a role in chronic hepatitis C virus (HCV) infection and influence the presence of hepatic fibrosis and comorbidities such as hepatic steatosis. We assessed the combined effect of SNPs in the PNPLA3, MTTP, TM6SF2, and IFNL3/IFNL4 genes in 288 Brazilian patients who were chronically infected with HCV. Hepatic fibrosis was observed in 246 (85.4%) patients and hepatic steatosis in 141 (49.0%) patients. PNPLA3 rs738409 (CG/GG) (P = 0.044) and TM6SF2 rs58542926 (CT) (P = 0.004) were alone associated with fibrosis, and PNPLA3 rs738409 (P < 0.05, in distinct genetic models) was associated with steatosis. Multiple logistic regression of each SNP combined with HCV genotype 3 infection showed that MTTP rs1800591 (GT/TT) combined with HCV genotype 3 was associated with a 6.72-fold increased chance of hepatic steatosis (P = 0.013). In the analysis of SNPs combined 2 by 2, no influence on hepatic fibrosis or steatosis was observed.

BACKGROUND

Recent genome-wide association studies demonstrated that 2 single nucleotide polymorphisms (SNPs), upstream of the interferon-λ (IFNL) 3 gene, are associated with the spontaneous clearance of hepatitis C virus (HCV) in symptomatic patients with acute hepatitis C (AHC). Although these 2 SNPs, rs8099917 and rs12979860, have established their significant roles in the innate immunity response to spontaneously clear HCV in patients with AHC, the detailed mechanisms of their roles remain largely unknown.

OBJECTIVE

This study is aimed at clarifying the factors affecting IFNL3 production and assessing the roles of IFNL3 in AHC.

METHODS

A total of 21 AHC patients who visited the hospital within 10 days after symptom onset were assessed. As controls, 23 healthy volunteers (HVs) were examined. Serum IFNL3 levels were quantified using an in-house, IFNL3-specific chemiluminescence enzyme immunoassay (CLEIA) kit. Serum IFNL1, IFN-α, IFN-β, and IFN-γ induced protein-10 (IP-10) levels were assayed using commercial enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

At baseline, serum IFNL3 levels were higher in AHC patients than in HVs (p < 0.0001). The higher levels in AHC patients did not differ between patients with the rs8099917 TT genotype and those with the non-TT (TG/GG) genotype (p = 0.546). Serial measurement of serum IFNL3 levels did not predict the outcome of conventional AHC. However, serum IFNL3 levels at baseline correlated positively with the HCV RNA levels (p = 0.005). Following HCV eradication, serum IFNL3 levels reduced to within the range obtained for HVs. Baseline serum IFNL1 levels did not differ significantly between AHC patients and HVs (p = 0.284). Serum levels of IFNL1 and IFNL3 at baseline also showed no correlative power (p = 0.288). Serum IFN-α and IFN-β were detected together with remarkably high serum IFNL3 levels in only one patient who progressed to acute liver failure (ALF).

CONCLUSIONS

These findings indicate that serum IFNL3 levels at baseline are higher in AHC patients regardless of the rs8099917 polymorphism, and primary HCV infection triggers the production of IFNL3. As a first line of defense in the innate immune system against invading HCV, increased IFNL3 levels play an important role, but serum IFNL3 levels are not the principal determinant of the clinical course of conventional AHC.

OBJECTIVE

To evaluate interferon-λ3 (IFNL3) polymorphisms in response-guided pegylated interferon-α plus ribavirin (Peg-IFNα/RBV) therapy for genotype 2 (G2) chronic hepatitis C.

METHODS

Between January 2006 and June 2012, a total of 180 patients with chronic infections of G2 hepatitis C virus (HCV) were treated with response-guided Peg-IFNα/RBV therapy. The treatment duration was 24 wk for patients who achieved rapid virologic response (RVR), and 36 or 48 wk for patients who did not. Then, the impact of the IFNL3 single nucleotide polymorphism genotype (TT/non-TT at rs8099917) on treatment outcomes was evaluated in the 180 patients, and between patients infected with either HCV sub-genotype 2a or 2b.

RESULTS

Of the 180 patients evaluated, 111 achieved RVR, while the remaining 69 patients did not. In RVR patients, the sustained virologic response (SVR) rate was 96.4%, and the IFNL3 genotype did not influence the SVR rate (96.6% vs 95.8% in IFNL3 genotype TT vs non-TT). However, in non-RVR patients, the SVR rate decreased to 72.5% (P < 0.0001), and this rate was significantly different between the IFNL3 genotype TT and non-TT groups (80.0% vs 42.9%, P = 0.0146). Multivariate regression analysis in non-RVR patients identified the IFNL3 genotype TT as the only baseline-significant factor associated with SVR (OR = 5.39, 95%CI: 1.29-22.62; P = 0.0189). In analysis according to HCV sub-genotype, no significant difference in the SVR rate was found between HCV sub-genotypes 2a and 2b.

CONCLUSIONS

In response-guided Peg-IFNα/RBV combination therapy for chronically HCV G2-infected patients, the impact of the IFNL3 genotype on SVR was limited to non-RVR patients.

Favourable genotypes of IFNL3 polymorphism CC for rs12979860 and TT for rs8099917 are strongly associated with the interferon/ribavirin treatment outcome in hepatitis C virus (HCV) patients with genotypes 1 and 4. Contrarily, conflicting results have been reported for patients with HCV genotypes 2 and 3. Therefore, we sought to investigate the association between IFNL3 with sustained virological response (SVR) after treatment to ascertain the predictive value of IFNL3 single-nucleotide polymorphisms (SNPs) in HCV patients with genotype 3. For this purpose, we genotyped five IFNL3 SNPs, rs12980275, rs12979860, rs9109886, rs8099917 and rs7248668, in HCV patients with genotype 3 and assessed its association with SVR, individually and in haplotype. Interestingly, we report that the IFNL3 SNPs we genotyped have shown no association with SVR following treatment, either individually or in haplotype, indicating that genotyping IFNL3 SNPs have limited predictive value in HCV patients with genotype 3. Therefore, we propose that IFNL3 genotyping can be excluded from a patient's pre-treatment workup for subsequent treatment choice. This will greatly reduce the economic burden for HCV patients with genotype 3 in resource-limited regions, especially South Asia where genotype 3 is predominant.

Background and study aims: Host genetic modifiers of the risk and persistence of hepatitis B virus (HBV) infection in the Pakistani population have not been clearly elucidated. Recently, two genome-wide association studies described that STAT4 and IFNL3 variants are associated with different aspects of the course of HBV infection. However, the roles of these variants in the persistence of HBV infection have not been investigated in the HBV-infected population of Pakistan. Therefore, we examined the roles of the STAT4 and IFNL3 variants in a chronic HBV-infected population from the Khyber Pakhtunkhwa (KPK) region of Pakistan.

Patients and methods: STAT4 rs7574865 and IFNL3 rs12979860 genotyping were performed in 297 subjects (240 infected with HBV and 57 controls). Statistical analyses were performed using the chi-squared test, Student's t-test, Hardy-Weinberg equilibrium tests and logistic regression models.

Results: Among the 297 subjects, compared with the IFNL3 rs12979860 genotype [odds ratio (OR) = 0.7, 95% confidence interval (CI) = 0.39-1.29, p = 0.2), the STAT4 rs7574865 genotype was independently associated with the risk of developing chronic HBV infection [OR = 1.9, 95% CI = 1.09-3.50, p = 0.02].

Conclusion: The STAT4 rs7574865 and not the IFNL3 rs12979860 variant is associated with persistence of HBV infection in a Pakistani population from the KPK region.

Keywords: Hepatitis B virus; Hepatocellular carcinoma; IFNL3; STAT4; Variants.

The frequency of single nucleotide polymorphisms of IFNL3 gene (rsl12979860 and rs8099917) and dinucleotide polymorphism of IFNL4 gene (ss469415590) were estimated in healthy inhabitants of Mongolia and Irkutsk regions taking into account their races. Population and genetic studies were performed in 1520 conventionally healthy volunteers (blood donors), representatives of Caucasian and Mongoloid races. Significant race-related differences in the incidence of IFNL3 and IFNL4 gene polymorphisms associated with spontaneous clearance of hepatitis C virus were found in healthy volunteers.

IFNL3 is the strongest predictor of spontaneous resolution (SR) of hepatitis C virus (HCV), however, consideration of IFNL3 genotype alone is of limited clinical value for the prediction of SR or chronic HCV infection. The objective of this study was to analyze the impact of HLA-B, HLA-C and KIRs on SR, as well as their additive effects on the predictive value of the IFNL3 genotype. We conducted a retrospective study of HIV patients that included both SR and chronic HCV patients. In our study, 61.6% of patients with IFNL3 CC achieved SR, and 81.5% with non-CC genotypes did not achieve SR. HLA-B*44, HLA-C*12, and KIR3DS1 were identified as predictive factors for SR, with percentages of 77.4%, 85.7% and 86.2%, respectively, for patients who did not experience SR. The presence of at least one of these three markers, defined as a genetically unfavorable profile (GUP), combined with the IFNL3 non-CC genotype showed a value of 100% for non-SR. The absence of the three markers, defined as a genetically favorable profile (GFP), in addition to the IFNL3 CC genotype showed a percentage of 74.1% for SR. The combination of these markers in addition to the IFNL3 genotype improves the predictive value of IFNL3 for SR of acute HCV infection in HIV patients, which would be clinically valuable.

Single-nucleotide polymorphisms (SNPs) occurring in immune-related genes have been associated with risk or protection for development of dengue, depending on ethnicity. Here, we genotyped seven SNPs located in immune response-related genes to identify their association with severe forms of dengue in patients from an endemic region in Mexico. One hundred and thirty-eight patients with dengue fever (DF), thirty-one dengue hemorrhagic fever (DHF) patients, as well as 304 healthy donors were genotyped by using a TaqMan-based approach. SNP analysis, including rs1800629 (TNF), rs4804803 (CD209), rs2780831 (JAK1), rs1801274 (FCGR2A), rs231775 (CTLA4), rs12979860, and rs8099917 (IFNL3), was performed. The rs1800629 A-allele in the TNF gene was associated with an increased risk of DHF (OR = 3.4, CI = 1.235-9.284 p = 0.0212) whereas SNPs rs4804803, rs2780831, rs1801274, rs231775, rs12979860, and rs8099917 showed no association in this cohort. These results show that allelic variations in TNF can play an important role in the development of DHF. However, the lack of association between all remaining SNPs and DHF suggests that the genetic background might directly modify the role of these immune-related molecules, leading to the milder illness often observed in a Mexican population.

Single nucleotide polymorphisms (SNPs) in immune-related genes have been shown to play a role in driving the development of the severe phenotypes of dengue virus (DENV) infection. We assessed the association between IFNL3 gene SNP (rs12979860) and dengue clinical outcomes in children. Patients with dengue-related symptoms (aged 1-15 years) admitted at a public hospital in Northeast Brazil were invited to participate. The association between rs12979860 polymorphism and dengue classification and clinical signs and symptoms were analysed. A total of 206 DENV-infected children were included: 53.4% of the infections were classified as severe dengue. The T allele carriers had higher risk of developing severe dengue when compared to CC genotype carriers (OR: 1.81; 95% CI: 0.98-3.32 p = .054). The T allele carriers also showed longer fever episodes when compared to patients with the CC genotype (OR: 1.90; 95%CI: 1.07-3.38; p = .027). On the other hand, the ones carrying the CT/TT genotype had 70% lower chance of developing thrombocytopenia when compared to those with the CC genotype (OR: 0.30; 95%CI: 0.08-0.88; p = .042). Our findings demonstrated that the T allele carriers of the IFNL3 gene had higher risk of developing severe dengue, suggesting a link between IFN-λ expression and DENV immunopathogenesis.

We conducted genotypic analyses of interleukin-10 (IL-10) (-1082 G/A; GG, GA, AA) and interleukin-28B (CC, CT, TT) genes polymorphisms in acute lymphoblastic leukemia (ALL) pediatric patients in descriptive study to evaluate the prevalence of these mutations. In amplification refractory mutation system-PCR (ARMS-PCR), one reaction was carried out for each patient's DNA sample. For IL-28B gene, two forward and two reverse primers specific for C-allele and T-allele were used separately. For human IL-10 gene, two different forward primers specific for A and G alleles were used in combination with common reverse primer. IL-10 gene promoter showed highest frequency (n=29, 58%) of heterozygous (GA) allele, while genotypic analysis of IL-28B gene showed highest frequency (n=28, 56%) of homozygous (CC) allele. The IL-10 (AA) genotype related to its protein's less production in body which may be associated with the least survival of ALL's patients, while IL-28b (CT and TT) genotypes may be associated with less IFNλ3 levels and less life expectancy.

IFNL3 gene plays a crucial role in immune defense against viruses. It induces the interferon stimulated genes (ISGs) with antiviral properties by activating the JAK-STAT pathway. In this study, we investigated the evolutionary force involved in shaping the IFNL3 gene to perform its downstream function as a regulatory gene in HCV clearance. We have selected 25 IFNL3 coding sequences with human gene as a reference sequence and constructed a phylogeny. Furthermore, rate of variation, substitution saturation test, phylogenetic informativeness and differential selection were also analysed. The codon evolution result suggests that nearly neutral mutation is the key pattern in shaping the IFNL3 evolution. The results were validated by subjecting the human IFNL3 protein variants to that of the native through a molecular dynamics simulation study. The molecular dynamics simulation clearly depicts the negative impact on the reported variants in human IFNL3 protein. However, these detrimental mutations (R157Q and R157W) were shown to be negatively selected in the evolutionary study of the mammals. Hence, the variation revealed a mild impact on the IFNL3 function and may be removed from the population through negative selection due to its high functional constraints. In a nutshell, our study may contribute the overall evidence in phylotyping and structural transformation that takes place in the non-synonymous substitutions of IFNL3 protein. Substantially, our obtained theoretical knowledge will lay the path to extend the experimental validation in HCV clearance.

Occult hepatitis C virus (HCV) infection (OCI) is described as the presence of viral genome in both hepatocytes and peripheral blood mononuclear cells (PBMCs) despite constant negative results on serum HCV RNA tests. Beta-thalassemia major (BTM) describes a group of inherited blood diseases. Patients with BTM require repeated blood transfusions, increasing the risk of exposure to infectious agents. We aimed to assess the prevalence of OCI in Iranian BTM patients and to identify the role of host factors in OCI positivity. A total of 181 BTM patients with HCV negative markers were selected. HCV RNA was tested in PBMCs using nested polymerase chain reaction assay. The positive samples were then genotyped via restriction fragment-length polymorphism (RFLP) and 5'-untranslated region sequencing. Six (3.3%) out of 181 BTM patients had viral HCV genomes in PBMC samples. Three (50.0%), two (33.3%), and one (16.7%) out of these six patients were infected with HCV-1b, HCV-1a, and HCV-3a, respectively. OCI positivity was significantly associated with the serum level of uric acid (P = 0.045) and ABO blood group (P = 0.032). Also, OCI patients had unfavorable IFNL3 rs12979860 TT, IFNL3 rs8099917 GG, IFNL3 rs12980275 GG, and IFNL4 ss469415590 ∆G/∆G genotypes. In conclusion, we indicated the low frequency of OCI in BTM patients. Nevertheless, more attention is warranted considering the importance of this infection. Also, further studies are necessary to determine the actual prevalence of OCI among BTM patients in Iran.

Background: It has been reported that interferon-λ3 (IFNL3)might influence the pathogenesis and clearance of human papillomavirus (HPV) infection. The impact of IFNL3 single-nucleotide polymorphism (SNP) on HPV infection is currently unknown. The aim of this study was to investigate the association between variants in the IFNL3 region and HPV infection in women with human immunodeficiency virus (HIV) infection.

Methods: A total of 236 HIV patients, including 65 HPV-negative and 171 HPV DNA-positive women, were enrolled into this study. The IFNL3 rs12979860 polymorphism was genotyped using a predesigned TaqMan SNP genotyping assay.

Results: Data showed no significant differences in genotypes or allele frequencies between the HPV DNA-positive and the HPV-negative women (p > 0.05). After dividing the HPV-positive women according to cytology results into patients with abnormal and normal lesions, the genotype and allele distribution of the SNP did not significantly differ between the 2 groups (p > 0.05).

Conclusions: Our results showed that the IFNL3 rs12979860 polymorphism is not a major determinant of the susceptibility to HPV infection and their progression to abnormal cervical lesions in women living with HIV.

Keywords: Cervical lesions; HPV; IL28B; Polymorphism; Susceptibility.

BACKGROUND AND RATIONALE FOR THE STUDY: Genome-wide association studies have identified host genetic variation to be critical for spontaneous clearance and treatment response in patients infected with hepatitis C virus. Recently, the role of the IFNL3 polymorphisms in influencing the spontaneous clearance of HCV, the response to interferon and the progression of liver fibrosis, was also demonstrated in patients with thalassemia major infected by genotype 1b. In the present study we retrospectively analyzed 368 anti-HCV positive patients with beta-thalassemia at two Italian major centers in Cagliari and Torino.

RESULTS

C/C variant of polymorphism rs12979860 was related to response to interferon treatment and, above all, to spontaneous clearance of the virus. However, the positive predictive power was stronger for viral persistence than spontaneous clearance and in such respect the TT allele was more predictive than CC. The methylation associated polymorphism rs4803221 had independent effects with respect to rs12979860 and the haplotype tagged by SNP rs12979860 and rs4803221 significantly could improve the viral clearance prediction in infected patients. Neither necroinflammation or bilirubin values in the chronic phase of the hepatitis C were related to IFNL3 polymorphisms. No relation among IFNL3 polymorphisms and fibrosis stage directly shown by the liver biopsy was found.

CONCLUSIONS

Also in thalassemia the SNPs on chromosome 19q13 closely associates with spontaneous and treatment-induced HCV clearance. The viral clearance prediction is significantly improved by the haplotype tagged by SNP rs12979860 and rs4803221. Neither necroinflammation, bilirubin values or fibrosis stage seem to be related to IFNL3 polymorphisms.

BACKGROUND

Kaposi's sarcoma, the most common AIDS-related cancer, represents a major public concern in resource-limited countries. Single nucleotide polymorphisms within the Interferon lambda 3/4 region (IFNL3/4) determine the expression, function of IFNL4, and influence the clinical course of an increasing number of viral infections.

OBJECTIVE

To analyze whether IFNL3/4 variants are associated with susceptibility to AIDS-related Kaposi's sarcoma among MSM enrolled in the Swiss HIV Cohort Study (SHCS).

METHODS

The risk of developing Kaposi's sarcoma according to the carriage of IFNL3/4 SNPs rs8099917 and rs12980275 and their haplotypic combinations was assessed by using cumulative incidence curves and Cox regression models, accounting for relevant covariables.

RESULTS

Kaposi's sarcoma was diagnosed in 221 of 2558 MSM Caucasian SHCS participants. Both rs12980275 and rs8099917 were associated with an increased risk of Kaposi's sarcoma (cumulative incidence 15 versus 10%, P = 0.01 and 16 versus 10%, P = 0.009, respectively). Diplotypes predicted to produce the active P70 form (cumulative incidence 16 versus 10%, P = 0.01) but not the less active S70 (cumulative incidence 11 versus 10%, P = 0.7) form of IFNL4 were associated with an increased risk of Kaposi's sarcoma, compared with those predicted not to produce IFNL4. The associations remained significant in a multivariate Cox regression model after adjustment for age at infection, combination antiretroviral therapy, median CD4 T-cell count nadir and CD4 slopes (hazard ratio 1.42, 95% confidence interval 1.06-1.89, P = 0.02 for IFLN P70 versus no IFNL4).

CONCLUSIONS

This study reports for the first time an association between IFNL3/4 polymorphisms and susceptibility to AIDS-related Kaposi's sarcoma.

Rabies, caused by rabies virus (RABV), is a fatal neurological disease that still causes more than 59,000 human deaths each year. Type III interferon IFN-λs are cytokines with type I IFN-like antiviral activities. Although IFN-λ can restrict the infection for some viruses, especially intestinal viruses, the inhibitory effect against RABV infection remains undefined. In this study, the function of type III IFN against RABV infection was investigated. Initially, we found that IFN-λ2 and IFN-λ3 could inhibit RABV replication in cells. To characterize the role of IFN-λ in RABV infection in a mouse model, recombinant RABVs expressing murine IFN-λ2 or IFN-λ3, termed as rB2c-IFNλ2 or rB2c-IFNλ3, respectively, were constructed and rescued. It was found that expression of IFN-λ could reduce the pathogenicity of RABV and limit viral spread in the brains by different infection routes. Furthermore, expression of IFN-λ could induce the activation of the JAK-STAT pathway, resulting in the production of interferon-stimulated genes (ISGs). It was also found that rRABVs expressing IFN-λ could reduce the production of inflammatory cytokines in primary astrocytes and microgila cells, restrict the opening of the blood-brain barrier (BBB), and prevent excessive infiltration of inflammatory cells into the brain, which could be responsible for the neuronal damage caused by RABV. Consistently, IFN-λ was found to maintain the integrity of tight junction (TJ) protein ZO-1 of BBB to alleviate neuroinflammation in a transwell model. Our study underscores the role of IFN-λ in inhibiting RABV infection, which potentiates IFN-λ as a possible therapeutic agent for the treatment of RABV infection.

Chronic hepatitis C virus (HCV) infection is characterized by high interindividual variability in response to pegylated interferon and ribavirin. A genetic polymorphism on chromosome 19 (rs12979860) upstream of interferon-λ3 (IFNλ3) is associated with a twofold change in sustained virologic response rate after 48 weeks of treatment with pegylated interferon/ribavirin in HCV genotype 1 (GT1) treatment-naïve patients. We conducted epigenetic analysis on the IFNλ3 promoter to investigate whether DNA methylation is associated with response to HCV therapy. DNA samples from HCV GT1-infected subjects receiving an interferon-free paritaprevir-containing combination regimen (N=540) and from HCV-uninfected, healthy controls (N=124) were analysed for IFNλ3 methylation levels. Methylation was strongly associated with rs12979860 allele status whether adjusting for HCV status (r=65.0%, 95% CI: [60.2%, 69.5%]), or not (r=64.4%), both with P<2.2×10-16 . In HCV GT1-infected subjects, C/C genotypes had significantly lower methylation levels relative to C/T or T/T genotypes (P<1×10-14 ), with each T allele resulting in a nine-unit increase in mean methylation level. Methylation levels did not correlate with response in subjects treated for 12 or 24 weeks. However, non-C/C subjects with higher methylation levels were more likely to relapse when treatment duration was 8 weeks. This analysis suggests that methylation status of the IFNλ3 promoter region may be a useful parameter that identifies patients more likely to relapse following HCV therapy; however, continuing therapy for a sufficient duration can overcome this difference. These findings may provide mechanistic insight into the role of IFNλ3 genetic variants in HCV treatment response.

Despite the introduction of protease inhibitors (PI) in the treatment of hepatitis C, the sensitivity of interferon continues to be essential to achieve a sustained virological response (SVR) and to eradicate the viral infection. Currently, pegylated interferon (PEG-IFN) and ribavirin (RBV) are required to avoid selection of PI-resistance mutations. The likelihood of obtaining an SVR with dual therapy in treatment-naïve patients with genotype 1 infection varies from 40% to 50%. That is, almost half of these patients would not require a PI, thus avoiding their adverse effects and considerably reducing the cost of the treatment. Identifying which patients could potentially respond to dual therapy is one of the main challenges in clinical practice. The genetic variability of the host is one of the main factors affecting the sensitivity of PEG-IFN and therefore in the response to current treatment. Other baseline factors related to the host, the virus and, especially, to intratreatment factors such as rapid virological response (RVR) are strongly associated with the probability of achieving an SVR. The evidence on the decision to prescribe dual or triple therapy according to the factors predictive of response is based on retrospective studies or post-hoc analyses of pivotal studies on PI. Study of the polymorphisms of the IFNL3 gene (IL28B), ITPA, IFN-stimulated genes (ISGs), TT/ΔG (ss469415590; IFNL4)) and RBV transporters could help in the decision to prescribe dual or triple therapy in treatment naïve patients.

The purpose of the present review is to summarise the current knowledge on the association between single nucleotide polymorphisms (SNPs) in the interferon L3 (IFNL3) gene and hepatitis C virus (HCV) infection in children. Many studies in adults have demonstrated that genetic variation in IFNL3 is a strong predictor of the virological response in treatment-naive patients with HCV genotype 1 who were treated with Pegylated-IFN-α and ribavirin. Genetic variation in IFNL3 is also associated with the spontaneous clearance of HCV. Thus far, few paediatric studies have explored the association between variations in the IFNL3 gene and either spontaneous or treatment-induced clearance of HCV. The CC genotype of the rs12979860 SNP is associated with the spontaneous clearance of HCV in children independently of HCV genotype. Four paediatric studies have shown that both the CC genotype of the rs12979860 SNP and the TT genotype of the rs8099917 SNP are associated with the treatment-induced (IFN monotherapy and Pegylated-IFN-α and ribavirin association) clearance of HCV, while the rs12980275 SNP did not affect the virological response. The possible role of IFNL3 gene variation as a pre-treatment and on-treatment predictor of virological response in children is highly attractive but still undetermined. Further paediatric studies are needed to evaluate if testing for SNPs in IFNL3, either alone or together with other predictors of response to treatment, could be used to direct treatment strategies, including an avoidance of unnecessary protease inhibitor therapy and the duration of treatment.