Burden of significant liver damage in people living with HIV after microelimination of the hepatitis C virus

BACKGROUND

Once HIV/HCV-coinfection microelimination has been virtually achieved in some countries, there is no information about the burden of liver disease among people living with HIV (PLWH). The aim of this study was to define the current prevalence and causes of significant liver damage (SLD) in PLWH.

METHODS

Cross-sectional study including 619 PLWH. SLD was defined as liver stiffness (LS) ≥ 7.2 kPa measured by transient elastography. Nonviral liver damage (NVLD) was considered if there was no evidence injury due to chronic hepatitis C virus (HCV) infection, active hepatitis B (HBV) or E virus infections.

RESULTS

One hundred and twelve of 619 (18.2%) PLWH showed SLD, including 34/112 (5.5%) with LS ≥14 kPa. 72/112 (64.3%) had cured HCV infection, 4/112 (3.6%) active HBV infection, and 2/112 HBV/prior HCV coinfection. Thus, 40 (35.7%) showed NVLD. Metabolic associated steatohepatitis (MASH) was present in 29/40 (72.5%) of patients with NVLD, alcoholic liver damage in 2/40 (2.5%) and mixed steatohepatitis in 5/40 (12.5%).

CONCLUSIONS

After HIV/HCV microelimination the burden of liver damage is high among PLWH. Persistent injury after HCV is a very frequent cause of SLD. However, NVLD, mainly due to MASH, is also a common condition in this population.

Incidence of recently acquired hepatitis C virus infection among HIV-infected patients in southern Spain

OBJECTIVES

Spain is close to HCV microelimination, so rates of recently acquired HCV infection (RAHC) should decrease. Nowadays, men who have sex with men (MSM) carry the highest risk of HCV acquisition. Our aim was to estimate the incidence of and the factors associated with RAHC, together with reinfection rates, among patients sexually infected by HIV.

METHODS

Primary RAHC infection was diagnosed when anti-HCV antibody seroconversion was documented. In anti-HCV positive patients, initially without HCV viraemia, a diagnosis of reinfection was established if plasma HCV RNA was detected.

RESULTS

All 350 patients tested negative for anti-HCV at baseline and had at least one follow-up visit. Among them, there were 16 RAHC cases from 2016 to 2019. RAHC incidence rates [IR (95% confidence interval, CI)] per 100 person-years were 3.77 (0.5-12.9) in 2016, 1.85 (0.6-4.3) in 2017, 1.49 (0.4-3.8) in 2018 and 1.98 (0.6-4.5) in 2019. Only previous sexually transmitted infections [incidence rate ratio (IRR) = 18.23, 95% CI: 1.93-172.1; P = 0.011], male sex (IRR = 8.33, 95% CI: 1.38-54.15; P = 0.026) and sharing chem-sex drugs (IRR: 4.93, 95% CI: 1.17-20.76; P = 0.030), were independently associated with RAHC. Four out of 42 (9.5%) patients became reinfected.

CONCLUSIONS

The incidence of RAHC among HIV-infected patients showed a decrease after 2016, although a lower but steady incidence of residual cases still remains. HCV reinfections showed a similar pattern. New infections were associated with sharing chem-sex drugs among MSM.

HIV infection is associated with lower risk of hepatocellular carcinoma after sustained virological response to direct-acting antivirals in hepatitis C infected-patients with advanced fibrosis

BACKGROUND

The aim of this study was to assess the impact of HIV infection on the risk of developing hepatocellular carcinoma (HCC) in HCV-infected patients who achieve sustained virological response (SVR) with direct-acting antiviral (DAA).

METHODS

Multisite prospective cohort study, where HCV-monoinfected patients and HIV/HCV-coinfected individuals were included if they met: 1) SVR with DAA-based combination; 2) Liver stiffness (LS) ≥9.5 kPa previous to treatment; 3) LS measurement at the SVR time-point. The main endpoint was the occurrence of HCC. Propensity score (PS) was calculated to address potential confounders due to unbalanced distribution of baseline characteristics of HIV/HCV-coinfected and HCV-monoinfected patients.

RESULTS

1035 HCV-infected patients were included, 667 (64%) coinfected with HIV. After a median (Q1-Q3) follow-up time of 43 (31-49) months, 19 (1.8%) patients developed HCC [11 (3.0%) HCV-monoinfected, 8(1.2%) HIV/HCV-coinfected individuals; p=0.013]. In the multivariable analysis, HIV co-infection was associated with a lower adjusted risk of developing HCC [sHR=0.27, 95% IC (0.08-0.90); p=0.034]. Predictors of HCC emergence were: HCV genotype 3 [sHR=7.9 (2.5-24.9); p<0.001], MELD score at SVR>10 [sHR=1.37 (1.01-1.86); p=0.043] and LS value at SVR [sHR=1.03 (1.01-1.06) for 1 kPa increase; p=0.011]. Using inverse probability weighting method on the PS, HIV-infected patients had a lower risk of HCC [powered HR=0.33 (0.11-0.85)].

CONCLUSIONS

Among HCV-infected patients with advanced fibrosis, who achieve SVR with DAA, HIV-coinfection seems to be associated with a lower risk of HCC occurrence. The underlying causes for this finding need to be investigated.

Similar prevalence of hepatic steatosis among patients with chronic hepatitis C with and without HIV coinfection

Hepatic steatosis (HS) is frequently observed in HIV-infected patients. It is not known whether HIV infection is an independent risk factor for HS development. We aimed to analyze whether HIV coinfection was associated with a higher frequency of HS in patients with chronic hepatitis C. This was a retrospective cross-sectional study. 574 subjects with chronic hepatitis C virus (HCV) infection were included, 246 (43%) of them coinfected with HIV. All of them underwent transient elastography with controlled attenuation parameter (CAP) measurement. HS was defined as CAP ≥ 248 dB/m. 147 individuals (45%) showed HS in the HCV-monoinfected group and 100 (40.7%) in the HIV/HCV-coinfected group (p = 0.318). HS was associated with body mass index (BMI) [<25 Kg/m² vs. ≥25 Kg/m², 67 (23.5%) vs. 171 (62.9%); p = 0.001], with plasma HDL-cholesterol [<50 mg/dL vs. ≥50 mg/dL, 122 (48.6%) vs. 95 (37.5%), p = 0.012], with plasma triglycerides [<150 mg/dL vs. ≥150 mg/dL, 168 (40.2%) vs. 65 (52.4%); p = 0.016] and with plasma total cholesterol [<200 mg/dL vs. ≥200 mg/dL, 181 (41%) vs. 53 (52.5%); p = 0.035]. In the multivariate analysis, HS was associated with BMI [adjusted OR (AOR) = 1.264 (1.194–1.339); p = 0.001], age [AOR = 1.029 (1.001–1.058); p = 0.047] and HCV genotype 3 infection [AOR = 1.901 (1.081–2.594); p = 0.026]. HIV coinfection was not associated with HS [AOR = 1.166 (0.719–1.892); p = 0.534]. In conclusion, HIV coinfection is not related with an increased frequency of HS in HCV-infected patients.

Changes in liver steatosis evaluated by transient elastography with the controlled attenuation parameter in HIV-infected patients

OBJECTIVES

There are scant data on the progression of hepatic steatosis (HS) in HIV infection. We therefore evaluated changes in HS over time in HIV-infected patients using the controlled attenuation parameter (CAP).

METHODS

A prospective cohort of 326 HIV-infected patients was included in this study. All patients underwent a CAP measurement. Changes in steatosis were evaluated by calculating the median (Q1-Q3) difference between baseline and 12-month CAP values.

RESULTS

The median (Q1-Q3) CAP was 221 (196-252) dB/m at baseline and 224 (198-257) dB/m at the 12-month visit (P = 0.617). Significant steatosis, that is, CAP ≥ 238 dB/m, was observed in 76 individuals (37%) at baseline and in 80 (39%) at the 12-month visit (P = 0.683). The following variables were associated with ΔCAP: plasma HIV RNA [< 50 vs. ≥ 50 HIV-1 RNA copies/mL: median (Q1-Q3) ΔCAP, 4 (-21, 27) vs. -21 (-49, 4) dB/m, respectively; P = 0.024]; body mass index (BMI) [no increase vs. increase: -13 (-40, 4) vs. 14 (-6, 32) dB/m, respectively; P < 0.001]; triglycerides [no increase vs. increase: -1 (-30, 22) vs. 15 (-3, 40) dB/m, respectively; P = 0.001]; fasting plasma glucose [not impaired vs. impaired: -4 (-31, 16) vs. 30 (15, 49) dB/m, respectively; P < 0.001]; and raltegravir [no vs. yes: 5 (-20, 29) vs. -11 (-37.5, 15) dB/m, respectively; P = 0.018]. The only factor independently associated with ΔCAP was BMI [B (standard error): 9.03 (1.9); P < 0.001].

CONCLUSIONS

Increases in CAP values over a period of 12 months in HIV-infected patients were strongly associated with elevations in BMI. Other metabolic factors and antiretroviral drugs were not predictors of CAP changes independent of BMI.

Rural habitat as risk factor for hepatitis E virus seroconversion in HIV-infected patients: A prospective longitudinal study

Our objective was to determine the incidence and clinical manifestations of acute hepatitis E virus (HEV) in HIV-infected patients. A prospective longitudinal study including HIV-infected HEV-seronegative patients was conducted; HEV seroconversion (to IgG and/or IgM) was the main outcome variable. All patients were tested for HEV antibodies every 3-6 months. For patients who developed HEV seroconversion, a data collection protocol was followed to identify associated clinical manifestations and analytical alterations. A total of 627 patients (89.9%) were followed during a median of 11.96 months (IQR: 8.52-14.52 months) and formed the study population. Forty-one patients developed detectable anti-HEV antibodies (7.2 cases per 100 patients/year). Our study found a high incidence of HEV in HIV-infected patients in southern Spain strongly associated with a rural habitat.

Fat mass and obesity-associated gene variations are related to fatty liver disease in HIV-infected patients

OBJECTIVES

Fatty liver disease (FLD) is frequently observed in HIV-infected patients. Obesity and type 2 diabetes mellitus (T2DM) are strongly associated with FLD. Because genetic variants within the fat mass and obesity-associated (FTO) gene have been associated with both pathologies, our aim was to evaluate the association of single nucleotide polymorphisms (SNPs) within the FTO, previously related to obesity or T2DM, with FLD in HIV-infected patients.

METHODS

FLD was defined as a value of the controlled attenuation parameter (CAP) ≥ 238 dB/m, obtained by transient elastography. Four SNPs within FTO intron 1 (rs11642841, rs8050136, rs9939609 and rs9940128) were genotyped in 421 individuals using a custom Golden Gate protocol. The results were replicated in a validation sample consisting of a further 206 HIV-infected patients. Multivariate logistic regression analyses were conducted in the entire population.

RESULTS

Three SNPs (rs8050136, rs9939609 and rs9940128) were associated with FLD, with rs9940128 showing the strongest association. This polymorphism also showed an association with FLD in the validation sample. In total, rs9940128 was genotyped in 627 HIV-infected patients, including 267 (42.6%) FLD-diagnosed individuals. The frequency of FLD among rs9940128 AA carriers was 55.7% (63 of 113 individuals) and that in patients without this genotype was 39.7% (204 of 514 individuals) [P = 0.009; adjusted odds ratio 1.88; 95% confidence interval (CI) 1.17-3.01].

CONCLUSIONS

Variations within FTO may be predictors of FLD in HIV-infected patients independently of metabolic factors.

High frequency of potential interactions between direct-acting antivirals and concomitant therapy in HIV/hepatitis C virus-coinfected patients in clinical practice

OBJECTIVES

The aim of the study was to analyse the frequency and degree of potential drug-drug interactions (DDIs) between direct-acting antivirals (DAAs) and concomitant medication used by HIV/hepatitis C virus (HCV)-coinfected patients, including antiretroviral therapy (ART) and other drugs.

METHODS

All patients with HIV infection and viraemic HCV genotype 1, 3 or 4 coinfection attending a tertiary care centre in Spain (November 2014 to November 2015) were included in the study. DDIs were classified as major, i.e. drugs should not be co-administered, or minor, i.e. close monitoring, dosage alteration or change in timing may be required if drugs are co-administered, following the http://www.hep-druginteractions.org database recommendations.

RESULTS

A total of 244 patients were included in the study, of whom 224 (92%) were previous injecting drug users. Major DDIs were found for: paritaprevir-r/ombitasvir plus dasabuvir (3D), in 60 (44%) of 138 individuals with genotype 1; paritaprevir-r/ombitasvir (2D), in 22 (37%) of 60 individuals with genotype 4; sofosbuvir/ledipasvir (SOF/LDV), in four (2%) of 198 patients with genotype 1 or 4; simeprevir (SMV) plus SOF, in 160 (81%) of 198 patients with genotype 1 or 4; daclatasvir (DCV) plus SOF, in seven (3%) of 244 patients with genotype 1, 3 or 4 (P < 0.001). Minor DDIs were found for: 3D, in 123 (89%) individuals with genotype 1; 2D, in 52 (87%) individuals with genotype 4; SOF/LDV, in 154 (78%) patients with genotype 1 or 4; SMV plus SOF, in 129 (65%) patients with genotype 1 or 4; DCV plus SOF, in 149 (61%) patients with genotype 1, 3 or 4 (P < 0.001).

CONCLUSIONS

Drug-drug interactions between DAAs and ART or other commonly prescribed medications are frequently found among HIV/HCV-coinfected patients. Potential major and minor DDIs are more frequent with 3D, 2D and SMV plus SOF regimens.

Longitudinal evaluation of hepatitis C viral persistence in HIV-infected patients with spontaneous hepatitis C clearance

Hepatitis C virus (HCV) viral persistence in patients with spontaneous viral clearance is controversial. Several studies have shown HCV-RNA in peripheral blood mononuclear cells (PBMCs) and/or liver tissue among patients who have cleared the virus spontaneously, suggesting that viral persistence is a common situation that could involve the entire population studied. Thus, our aim was to evaluate HCV-RNA persistence in PBMCs and hepatocytes in subjects infected with the human immunodeficiency virus (HIV). A total of 1508 patients were prospectively followed and tested for anti-HCV antibodies and HCV-RNA to identify the patients who achieved spontaneous viral clearance. In all of the patients, the persistence of HCV-RNA in PBMCs was evaluated longitudinally during 2 years of follow-up. Fifty-nine patients fulfilled the inclusion/exclusion criteria and were included in the study. HCV-RNA was not detected in the PBMCs at baseline [59 PBMCs samples tested; 0 %; 95 % confidence interval (CI): 0-3.3 %] or during the follow-up (147 PBMCs samples tested; 0 %; 95 % CI: 0-2.02 %). Our study shows that HCV viral persistence is not a frequent occurrence in HIV-infected patients who have spontaneously resolved an HCV infection. Thus, the lack of serum HCV-RNA should continue to be addressed as the standard of healing.

Impact of HIV infection on sustained virological response to treatment against hepatitis C virus with pegylated interferon plus ribavirin

It is commonly accepted that human immunodeficiency (HIV) coinfection negatively impacts on the rates of sustained virological response (SVR) to therapy with pegylated interferon plus ribavirin (PR). However, this hypothesis is derived from comparing different studies. The aim of this study was to determine the impact of HIV coinfection on SVR to PR in one single population. In a multicentric, prospective study conducted between 2000 and 2013, all previously naïve hepatitis C virus (HCV)-infected patients who started PR in five Spanish hospitals were analyzed. SVR was evaluated 24 weeks after the scheduled end of therapy. Of the 1046 patients included in this study, 413 (39%) were coinfected with HIV. Three hundred and forty-one (54%) HCV-monoinfected versus 174 (42%) HIV/HCV-coinfected patients achieved SVR (p < 0.001). The corresponding figures for undetectable HCV RNA at treatment week 4 were 86/181 (47%) versus 59/197 (30%), p < 0.001. SVR was observed in 149 (69%) HCV genotype 2/3-monoinfected subjects versus 91 (68%) HIV/HCV genotype 2/3-coinfected subjects (p = 0.785). In the HCV genotype 1/4-infected population, 188 (46%) monoinfected patients versus 82 (30%) with HIV coinfection (p < 0.001) achieved SVR. In this subgroup, absence of HIV coinfection was independently associated with higher SVR [adjusted odds ratio (95% confidence interval): 2.127 (1.135-3.988); p = 0.019] in a multivariate analysis adjusted for age, sex, baseline HCV RNA load, IL28B genotype, fibrosis stage, and type of pegylated interferon. HIV coinfection impacts on the rates of SVR to PR only in HCV genotype 1/4-infected patients, while it has no effect on SVR in the HCV genotype 2/3-infected subpopulation.

Association of complement receptor 2 polymorphisms with innate resistance to HIV-1 infection

HIV-1 induces activation of complement through the classical and lectin pathways. However, the virus incorporates several membrane-bound or soluble regulators of complement activation (RCA) that inactivate complement. HIV-1 can also use the complement receptors (CRs) for complement-mediated antibody-dependent enhancement of infection (Ć-ADE). We hypothesize that hypofunctional polymorphisms in RCA or CRs may protect from HIV-1 infection. For this purpose, 139 SNPs located in 19 RCA and CRs genes were genotyped in a population of 201 Spanish HIV-1-exposed seronegative individuals (HESN) and 250 HIV-1-infected patients. Two SNPs were associated with infection susceptibility, rs1567190 in CR2 (odds ratio (OR) = 2.27, P = 1 × 10(-4)) and rs2842704 in C4BPA (OR = 2.11, P = 2 × 10(-4)). To replicate this finding, we analyzed a cohort of Italian, sexually HESN individuals. Although not significant (P = 0.25, OR = 1.57), similar genotypic proportions were obtained for the CR2 marker rs1567190. The results of the two association analyses were combined through a random effect meta-analysis, with a significant P-value of 2.6 x 10(-5) (OR = 2.07). Furthermore, we found that the protective CR2 genotype is correlated with lower levels CR2 mRNA as well as differences in the ratio of the long and short CR2 isoforms.

Association of low-density lipoprotein receptor genotypes with hepatitis C viral load

Several data suggest that low-density lipoprotein receptor (LDLR) is a co-receptor for hepatitis C virus (HCV). Soluble LDLR can inhibit HCV infectivity; greater plasma low-density lipoprotein levels are associated with treatment success; LDLR genotypes have a synergistic impact on the likelihood of achieving SVR with Peg-IFN plus RBV, as well as on viral kinetics after starting treatment. The objective of this study was to assess the impact of genetic polymorphisms in genes related to cholesterol synthesis and transport pathways on pre-treatment plasma HCV viral load (VL). A total of 442 patients infected with HCV and treatment naive were prospectively recruited. One hundred forty-four SNPs located in 40 genes from the cholesterol synthesis/transport and IL28B were genotyped and analyzed for genetic association with pre-treatment plasma HCV VL. SNPs rs1433099 and rs2569540 of LDLR showed association with plasma HCV VL (P=4 × 10(-4) and P=2 × 10(-3)) in patients infected with genotypes 1 and 4. A haplotype including the last three exons of LDLR showed association with the cutoff level of 600 000 IU ml(-1) VL for genotypes 1 and 4 (OR=0.27; P=8 × 10(-6)), as well as a quantitative VL (mean±s.d.: 6.19±0.9 vs CC+CG 5.58±1.1 logIU ml(-1), P=8 × 10(-5)). LDLR genotypes are a major genetic factor influencing HCV VL in patients infected with genotypes 1 and 4.

GAB2 gene does not modify the risk of Alzheimer's disease in Spanish APOE 4 carriers

OBJECTIVES

The genetic basis of Alzheimer's disease (AD) is being analyzed in multiple whole genome association studies (WGAS). The GAB2 gene has been proposed as a modifying factor of APOE epsilon 4 allele in a recent case-control WGAS conducted in the US. Given the potential application of these novel results in AD diagnostics, we decided to make an independent replication to examine the GAB2 gene effect in our series.

DESIGN

We are conducting a multicenter population-based study of AD in Spain.

PARTICIPANTS

We analyzed a total of 1116 Spanish individuals. Specifically, 521 AD patients, 475 controls from the general population and 120 neurologically-normal elderly controls (NNE controls).

METHODS

We have genotyped GAB2 (rs2373115 G/T) and APOE rs429358 (SNP112)/rs7412 (SNP158) polymorphisms using real time-PCR technologies.

RESULTS

As previously reported in Spain, APOE epsilon 4 allele was strongly associated with AD in our series (OR=2.88 [95% C.I. 2.16- 3.84], p=7.38E-11). Moreover, a large effect for epsilone 4/epsilone 4 genotype was also observed (OR=14.45 [95% C.I., 3.34-125.2], p=1.8E-6). No difference between the general population and the NNE controls series were observed for APOE genotypes (P > 0.61). Next, we explored GAB2 rs2373115 SNP singlelocus association using different genetic models and comparing AD versus controls or NNE controls. No evidence of association with AD was observed for this GAB2 marker (p > 0.17). To evaluate GAB2-APOE genegene interactions, we stratified our series according to APOE genotype and case-control status, in accordance with the original studies. Again, no evidence of genetic association with AD was observed in any strata of GAB2-APOE loci pair (p > 0.34).

CONCLUSION

GAB2 rs2373115 marker does not modify the risk of Alzheimer's disease in Spanish APOE epsilon 4 carriers.

CAPN10 alleles modify laryngeal cancer risk in the Spanish population

AIMS

Laryngeal carcinoma is a common upper respiratory tract cancer with different environmental and genetic factors involved in its development. To date, CAPN10 has been found to be extensively associated with hyperinsulinaemia and type 2 diabetes mellitus, by different groups. In addition, some reports have shown evidence that hyperinsulinaemia exerts a protective effect on laryngeal cancer risk. On the other hand, low circulating levels of IGF-1 have been recently found in patients with laryngeal carcinoma. Our objective was to examine the contribution of CAPN10 alleles to the development of laryngeal cancer.

METHODS

Cases and controls were recruited from central and southern Spain. Genotypes were determined using pyrosequencing technology. We analysed CAPN10 UCSNP-44, -43, -19, and -63 allelic distribution in 218 unrelated laryngeal cancer patients and 606 controls from the general population.

RESULTS

We found that the UCSNP-44 allele-C is significantly under-represented among patients with laryngeal cancer (OR=0.685, p=0.02).

CONCLUSION

These results indicate that some CAPN10 alleles may be exerting a protective effect on laryngeal cancer risk in the Spanish population.

Association of genetic markers within the KIT and KITLG genes with human male infertility

BACKGROUND

There is much evidence involving the KIT tyrosine kinase receptor and its ligand KITLG in the survival and proliferation of germ cells. Animal models and functional studies in humans suggest that this signalling pathway plays a role in male infertility.

METHODS

We studied three and two single-nucleotide polymorphisms (SNPs) (rs3819392, rs3134885, rs2237012, rs10506957 and rs995030) located within the genomic region of the KIT and KITLG genes, respectively. A total of 167 idiopathic infertile men (sperm counts <5 million spz/ml) and 465 unrelated healthy controls from the same geographical region were genotyped for these SNPs.

RESULTS

We found a statistically significant association of the rs3819392 polymorphism, which is located within the KIT gene, with idiopathic male infertility. In addition, a deviation from the Hardy-Weinberg equilibrium (HWE) law was observed for rs10506957 polymorphism within the KITLG gene only in the infertile group.

CONCLUSIONS

Our data indicate that the KIT/KITLG system may be involved in a low sperm count trait in humans.

Specific haplotypes of the CALPAIN-5 gene are associated with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age. The aim of the present study was to investigate the role of CALPAIN-5 (CAPN5) gene in PCOS susceptibility.

METHODS

We analysed four intronic polymorphisms of the CAPN5 gene in 148 well-characterized women with PCOS and 606 unrelated controls. We performed a case-control study and an intracohort analysis of clinical characteristics associated with PCOS.

RESULTS

Analysis of haplotypes distribution between PCOS population compared to controls showed a strong deviation (P = 0.00029). The haplotypes GGCA and GGTG were overrepresented in PCOS patients (P = 0.009 and P = 0.001, respectively). In addition, we identified several CAPN5 haplotypes associated with phenotypic differences observed between PCOS patients, such as the presence of obesity (P = 0.02), cardiovascular complications (P = 0.02), familial antecedents of obesity (P = 0.003) and of hypertension (P = 0.007) and type 2 diabetes mellitus aggregation (P = 0.04).

CONCLUSIONS

These results suggest a role of CAPN5 gene in PCOS susceptibility in humans. Moreover, novel candidate risk alleles have been identified, within CAPN5 gene, which could be associated with important phenotypic and prognosis differences observed in PCOS patients.

Multiple mechanisms of immune evasion can coexist in melanoma tumor cell lines derived from the same patient

Progressive tumor growth may be associated with suppression of the immune response. Many different mechanisms may contribute to immune evasion. We investigated some of these mechanisms in melanoma cells lines generated from two patients. These cell lines show a complex pattern of altered HLA expression; however, the resulting phenotype did not satisfactorily explain the simultaneous evasion of T and NK cell cytotoxicity. Two additional alterations have now been detected in these melanoma cell lines: (1) resistance to FAS-induced apoptosis caused by defective FAS gene expression, and (2) constitutive expression of immunosuppressive cytokines. Our results show that several of the major mechanisms for immune evasion may coexist in a single tumor. This suggests that tumor progression may give rise to an extremely resistant phenotype, which may be an impediment to some immunotherapeutic strategies. We hypothesize that the simultaneous presence of several mechanisms involved in tumor immune evasion must be the result of progressive selection of characteristics that are advantageous for tumor survival in a competent host. Our findings do not support the possibility that FASL expression is a common mechanism of evasion of immune response in melanoma cells.

Microsatellite instability analysis in tumors with different mechanisms for total loss of HLA expression

Down-regulation of the expression of major histocompatibility complex molecules is a frequent event that is associated with the poor immunogenicity of tumor cells. Acquired resistance to T-cell-based immunotherapy has been associated with loss of functional beta2-microglobulin expression. This anomaly appears to be particularly relevant in tumors exhibiting a defect in DNA-mismatch repair, and induces structural abnormalities in HLA cell-surface expression that are not reversible by cytokine treatment. We examined HLA expression in 118 melanoma, colon or larynx tumors to identify total loss of HLA class I expression with or without somatic beta2-microglobulin gene mutation. Microsatellite instability was investigated in these tumors to determine whether a replication error phenotype (RER+) implied a particular alteration in HLA phenotype. A total of 7.6% of the tumors showed the RER+ phenotype, and 12.7% were HLA-ABC-negative. In the RER+ group, only one tumor was HLA-ABC-negative and no beta2-microglobulin mutation was identified. In contrast, in the HLA-ABC-negative group, only one tumor showed microsatellite instability. None of the three melanomas that contained beta2-microglobulin mutation exhibited the mutator phenotype. These findings suggest that beta2-microglobulin mutation in human melanoma tumors may arise through a mechanism that does not necessarily involve microsatellite instability. Our results also indicate that somatic mutations of the beta2-microglobulin gene are not the main mechanism of total loss of HLA expression.

Chromosome loss is the most frequent mechanism contributing to HLA haplotype loss in human tumors

Loss of heterozygosity (LOH) in the short arm of chromosome 6 (6p) was detected in samples obtained from colon (13.8%), larynx (17.6%) and melanoma (15.3%) tumors. The parallel study of HLA-antigen expression in tumor tissues using locus- and polymorphic-specific antibodies in combination with LOH microsatellite analysis on 6p allowed us to establish that LOH in chromosome 6 is a representative phenomenon in most tumor cells present in a given tumor tissue. In most cases, specific HLA alleles had been lost in a predominant population of tumor cells, indicating that LOH is a non-irrelevant mutation that probably confers a selective advantage for survival of the mutant cell. We also demonstrate that LOH frequently occurred through chromosome loss rather than somatic recombination. LOH at all loci studied on the p and q arms of chromosome 6 was observed in at least 56.2% (9/17) cases. This HLA-associated microsatellite analysis was a useful tool for classifying tumors as LOH-positive or -negative, and therefore to consider a patient as a potential non-responder or responder in a vaccination trial.

Looking for HLA-G expression in human tumours

Tumour and virus infected cells escape CTLs responses by losing some or all HLA class I molecules. However the NK escape mechanism that uses the HLA-A, -B, and -C tumour deficient variants is unknown. To determine whether HLA-G is expressed on tumour cells and thus favours tumour escape by abolishing NK lysis, we studied HLA-G in a large panel of human tumour tissues and human tumour cell lines of different origin that were previously characterized for HLA-A, -B, and -C expression. We studied HLA-G mRNA transcripts using RT-PCR, and HLA-G1 expression by FACS and immunohistochemical techniques. We found several mRNA transcripts of HLA-G isoforms in most of the samples studied. However, we detected no cell surface expression of HLA-G1 using two specific monoclonal antibodies (mAbs) (87G and 01G). We cannot, however, exclude the possibility that some isoforms other than HLA-G1 may be expressed in some tumours.

Expression of HLA G in human tumors is not a frequent event

Expression of HLA G may be a way for tumor cells to escape immuno-surveillance. HLA G is selectively expressed by extravillous trophoblast in the human placenta, a tissue that does not express HLA A or B molecules. It is tempting to propose that tumor cells resemble this unique HLA class I phenotype as they frequently lose classical HLA A, B and C class I expression. Such peculiar HLA class I distribution would in theory allow tumor cells to escape from T- and NK-cell cytotoxicity. To determine whether HLA G is expressed on tumor cells, we studied HLA G mRNA levels using RT-PCR and HLA G cell-surface expression by immunohistological techniques in a panel of 50 human solid tumor tissues, 31 tumor cell lines of different origin, 4 autologous mucosa samples and 3 peripheral white cell samples. We found mRNA transcripts of different HLA G isoforms in most of the samples studied. However, we did not detect cell-surface expression of HLA G using 3 specific monoclonal antibodies (MAbs; 87G, 01G and G223). HLA G was detected only in the U937 myelomonocytic cell line after stimulation with IFN-gamma. We favor the hypothesis that HLA G plays a minor role, if any, in providing an inhibitory signal to NK cells to escape immunosurveillance. We cannot, however, exclude the possibility that some other HLA G isoforms may be expressed in some tumors.

Differential effect on U937 cell differentiation by targeting transcriptional factors implicated in tissue- or stage-specific induced integrin expression

The inhibition of transcription factor functions was used to define their role in phorbol ester-induced cellular differentiation of a monocytic cell line, U937. We demonstrate a differential effect on cell adhesion and differentiation: antisense or competitive binding with double-stranded oligonucleotides antagonized the functions of AP-1, NF-kappaB, and PU.1 transcriptional factors. In the presence of phorbol 12-myristate 13-acetate (PMA), U937 cells attached to the plastic surface and cells were characterized by marked expression of beta2-integrin molecules on the cell surface. We show that the in vivo differentiation of U937 cells appears to occur normally in the absence of AP-1 activity. In contrast, the addition to the cell culture of phosphorothioate oligonucleotides that contained the NF-kappaB or PU.1 binding sites significantly inhibited U937 differentiation. The absence of NF-kappaB led to pleiotropic effects with a clear reduction in the expression of integrin and other lineage-specific myeloid antigens on the cell surface. In contrast, the absence of PU.1 had a more restricted effect on integrin expresion on the cell surface, probably as a result of blockage of CD18 gene expression.

Unresponsiveness to interferon associated with STAT1 protein deficiency in a gastric adenocarcinoma cell line

HC class I expression can be up-regulated by interferons (IFN) and other cytokines. Both IFNalpha and IFNgamma have been shown to exert their effects via a recently discovered signalling pathway by inducing tyrosine phosphorylation of their receptors. Receptors for interferons and other cytokines signal through the action of associated protein tyrosine kinases of the JAK family (Janus kinase) and latent cytoplasmic transcriptional activators from the STAT family (signal transducers and activators of transcription). Here we report a gastric adenocarcinoma cell line, AGS, that is defective in its response to either IFNalpha or IFNgamma. AGS cells display selective alterations only in MHC class I inducibility and not in constitutive MHC class I expression. In nuclear extracts of AGS cells, no binding activity to interferon-responsive elements (GAS/ISRE) was observed. We found that AGS cells showed an extremely low level of STAT1 expression, which may be responsible for the absence of biological response to IFN. Because STAT1-deficient cells are highly sensitive to infection by virus, the absence of these proteins may also contribute to the tumor phenotype, giving the tumor a selective advantage, by inhibiting cell growth suppression mediated by IFN and abetting escape from the T cell antitumor response.

Microsatellite instability in cervical intraepithelial neoplasia

We studied the incidence of microsatellite instability (MI) in lesions defined as cervical intraepithelial neoplasia (CIN). The human papillomavirus (HPV) status of the tissues was also determined. DNA from tissue samples and autologous lymphocytes were studied for five loci located within or adjacent to the DNA mismatch repair genes. Replicate errors were detected in 7 out of 47 (14.8%) samples of cervical tissue from 24 women. Our results indicate that the defect in DNA repair-associated genes does not appear to be necessary for the selection of clones which progress from dysplasia to carcinoma. Although HPV DNA of highly oncogenic types (16/18) was detected in most cervical lesions and may be an important factor for MI, we also detected MI in two loci in HPV-negative normal tissue, indicating that further events can also be involved in mismatch repair defects.

In vivo and in vitro generation of a new altered HLA phenotype in melanoma-tumour-cell variants expressing a single HLA-class-I allele

A new HLA-class-I altered phenotype is described in melanoma. This phenotype is the result of a combination of HLA-B-locus down-regulation and HLA-haplotype loss. The alteration was found in 2 melanoma cell lines generated from 2 patients; one was derived from an in vivo lesion (FM37) and the other was obtained after in vitro immunoselection (R22.2). The R22.2 cell line was isolated from FM55P, a cell line derived from a primary melanoma, after in vitro treatment with a heterologous HLA-A2-restricted cytotoxic-T-lymphocyte (CTL) clone. Two additional cell lines from patient 55 were obtained from 2 s.c. metastases (FM55M1 and FM55M2). Iso-electric focusing and flow-cytometric studies showed a significant reduction in the expression of both HLA-B alleles in all cell lines studied. The expression of HLA-B-locus products recovered completely after IFN-gamma treatment of FM55P, M1 and M2. In contrast, FM37 and R22.2 tumour cells showed an additional HLA defect: the absence of one HLA haplotype. Simple tandem-repeat polymorphism markers spanning chromosome 6 showed that DNA from the 2 samples (FM37 and R22.2) showed loss of heterozygosity (LOH). In both cases, homozygosity was observed on 6p, which maps the HLA region, the final consequence being a tumour cell that expressed a single HLA-class-I allele (HLA-A3 and HLA-A1 respectively). FM37 cells may thus reflect the in vivo counterpart of resistance to lysis by HLA-A2-restricted tumour-infiltrating lymphocytes.