The density of hepatic autonomic innervation differs between compensatory and direct hyperplasia rat models.

To contribute to the knowledge of the autonomic innervation in liver regeneration, here we investigate the distribution of tyrosine hydroxylase (TH)- and choline acetyltransferase (ChAT)-like immunoreactive (LI) nerve fibers, to indicate noradrenergic and cholinergic nerves, respectively, in rats under different conditions of liver damage and repair. By immunohistochemistry and assessment of nerve fiber density, three models of induced hepatic regeneration were examined: the carbon tetrachloride (CCl4 ) intoxication, with two treatment periods of 14 weeks and 18 weeks; the partial hepatectomy (PH); the thyroid hormone (T3) treatment. TH- and ChAT-LI nerve fibers were detectable mostly in the portal spaces, the TH-LI ones occurring only around blood vessels while the ChAT-LI nerve fibers were also associated with secretory ducts. The density of TH-like immunoreactivity in the portal areas decreased after the CCl4 14 weeks treatment and PH and increased after T3. By contrast, ChAT-LI nerve fibers appeared particularly abundant around the neoductal elements in the CCl4 rats and were rare to absent in the PH and T3-treated groups. The ChAT-LI nerve fiber density within the portal areas revealed an increase in the CCl4 -treated rats while showing no change in the PH and T3-treated rats. The changes in the density of perivascular TH- and ChAT-containing nerve fibers suggest a finely tuned autonomic modulation of hepatic blood flow depending on the type of subacute/chronic induced hyperplasia, while the characteristic occurrence of the periductal cholinergic innervation after the CCl4 treatment implies a selective parasympathetic role in regulating the physiopathological regenerative potential of the rat liver.

Multi-Organ Morphological Findings in a Humanized Murine Model of Sickle Cell Trait.

Sickle cell disease (SCD) is caused by the homozygous beta-globin gene mutation that can lead to ischemic multi-organ damage and consequently reduce life expectancy. On the other hand, sickle cell trait (SCT), the heterozygous beta-globin gene mutation, is still considered a benign condition. Although the mechanisms are not well understood, clinical evidence has recently shown that specific pathological symptoms can also be recognized in SCT carriers. So far, there are still scant data regarding the morphological modifications referable to possible multi-organ damage in the SCT condition. Therefore, after genotypic and hematological characterization, by conventional light microscopy and transmission electron microscopy (TEM), we investigated the presence of tissue alterations in 13 heterozygous Townes mice, one of the best-known animal models that, up to now, was used only for the study of the homozygous condition. We found that endothelial alterations, as among which the thickening of vessel basal lamina, are ubiquitous in the lung, liver, kidney, and spleen of SCT carrier mice. The lung shows the most significant alterations, with a distortion of the general tissue architecture, while the heart is the least affected. Collectively, our findings contribute novel data to the histopathological modifications at microscopic and ultrastructural levels, underlying the heterozygous beta-globin gene mutation, and indicate the translational suitability of the Townes model to characterize the features of multiple organ involvement in the SCT carriers.

TG68, a Novel Thyroid Hormone Receptor-ß Agonist for the Treatment of NAFLD.

Activation of thyroid hormone receptor ß (THRß) has shown beneficial effects on metabolic alterations, including non-alcoholic fatty liver disease (NAFLD). Here, we investigated the effect of TG68, a novel THRß agonist, on fatty liver accumulation and liver injury in mice fed a high-fat diet (HFD). C57BL/6 mice fed HFD for 17 or 18 weeks, a time when all mice developed massive steatohepatitis, were then given TG68 at a dose of 9.35 or 2.8 mg/kg for 2 or 3 weeks, respectively. As a reference compound, the same treatment was adopted using equimolar doses of MGL-3196, a selective THRß agonist currently in clinical phase III. The results showed that treatment with TG68 led to a reduction in liver weight, hepatic steatosis, serum transaminases, and circulating triglycerides. qRT-PCR analyses demonstrated activation of THRß, as confirmed by increased mRNA levels of Deiodinase-1 and Malic enzyme-1, and changes in lipid metabolism, as revealed by increased expression of Acyl-CoA Oxidase-1 and Carnitine palmitoyltransferase-1. The present results showed that this novel THRß agonist exerts an anti-steatogenic effect coupled with amelioration of liver injury in the absence of extra-hepatic side effects, suggesting that TG68 may represent a useful tool for the treatment of NAFLD.

Thyroid hormone inhibits hepatocellular carcinoma progression via induction of differentiation and metabolic reprogramming.

BACKGROUND & AIMS: Only limited therapeutic options are currently available for hepatocellular carcinoma (HCC), making the development of effective alternatives essential. Based on the recent finding that systemic or local hypothyroidism is associated with HCC development in humans and rodents, we investigated whether the thyroid hormone triiodothyronine (T3) could inhibit the progression of HCCs. METHODS: Different rat and mouse models of hepatocarcinogenesis were investigated. The effect of T3 on tumorigenesis and metabolism/differentiation was evaluated by transcriptomic analysis, quantitative reverse transcription PCR, immunohistochemistry, and enzymatic assay. RESULTS: A short treatment with T3 caused a shift in the global expression profile of the most aggressive preneoplastic nodules towards that of normal liver. This genomic reprogramming preceded the disappearance of nodules and involved reprogramming of metabolic genes, as well as pro-differentiating transcription factors, including Kruppel-like factor 9, a target of the thyroid hormone receptor ß (TRß). Treatment of HCC-bearing rats with T3 strongly reduced the number and burden of HCCs. Reactivation of a local T3/TRß axis, a switch from Warburg to oxidative metabolism and loss of markers of poorly differentiated hepatocytes accompanied the reduced burden of HCC. This effect persisted 1 month after T3 withdrawal, suggesting a long-lasting effect of the hormone. The antitumorigenic effect of T3 was further supported by its inhibitory activity on cell growth and the tumorigenic ability of human HCC cell lines. CONCLUSIONS: Collectively, these findings suggest that reactivation of the T3/TRß axis induces differentiation of neoplastic cells towards a more benign phenotype and that T3 or its analogs, particularly agonists of TRß, could be useful tools in HCC therapy. LAY SUMMARY: Hepatocellular carcinoma (HCC) represents an important challenge for global health. Recent findings showed that systemic or local hypothyroidism is associated with HCC development. In rat models, we showed that administration of the thyroid hormone T3 impaired HCC progression, even when given at late stages. This is relevant from a translational point of view as HCC is often diagnosed at an advanced stage when it is no longer amenable to curative treatments. Thyroid hormones and/or thyromimetics could be useful for the treatment of patients with HCC.

GC-1: A Thyromimetic With Multiple Therapeutic Applications in Liver Disease.

Thyroid hormones (THs), namely, 3,5,3'-triiodo-l-thyronine (T3) and 3,5,3',5'-tetraiodo-l-thyronine (thyroxine or T4), influence a variety of physiological processes that have important implications in fetal development, metabolism, cell growth, and proliferation. While THs elicit several beneficial effects on lipid metabolism and improve myocardial contractility, these therapeutically desirable effects are associated to a thyrotoxic state that severely limits the possible use of THs as therapeutic agents. Therefore, several efforts have been made to develop T3 analogs that could retain the beneficial actions (triglyceride, cholesterol, obesity, and body mass lowering) without the adverse TH-dependent side effects. This goal was achieved by the synthesis of TRß-selective agonists. In this review, we summarize the current knowledge on the effects of one of the best characterized TH analogs, the TRß1-selective thyromimetic, GC-1. In particular, we review some of the effects of GC-1 on different liver disorders, with reference to its possible clinical application. A brief comment on the possible therapeutic use of GC-1 in extrahepatic disorders is also included.

Statistical Health Monitoring Applied to a Metabolomic Study of Experimental Hepatocarcinogenesis: An Alternative Approach to Supervised Methods for the Identification of False Positives.

In a typical metabolomics experiment, two or more conditions (e.g., treated versus untreated) are compared, in order to investigate the potential differences in the metabolic profiles. When dealing with complex biological systems, a two-class classification is often unsuitable, since it does not consider the unpredictable differences between samples (e.g., nonresponder to treatment). An approach based on statistical process control (SPC), which is able to monitor the response to a treatment or the development of a pathological condition, is proposed here. Such an approach has been applied to an experimental hepatocarcinogenesis model to discover early individual metabolic variations associated with a different response to the treatment. Liver study was performed by nuclear magnetic resonance (NMR) spectroscopy, followed by multivariate statistical analysis. By this approach, we were able to (1) identify which treated samples have a significantly different metabolic profile, compared to the control (in fact, as confirmed by immunohistochemistry, the method correctly classified 7 responders and 3 nonresponders among the 10 treated animals); (2) recognize, for each individual sample, the metabolites that are out of control (e.g., glutathione, acetate, betaine, and phosphocholine). The first point could be used for classification purposes, and the second point could be used for a better understanding of the mechanisms underlying the early phase of carcinogenesis. The statistical control approach can be used for diagnosis (e.g., healthy versus pathological, responder versus nonresponder) and for generation of an individual metabolic profile, leading to a better understanding of the individual pathological processes and to a personalized diagnosis and therapy.

Local hypothyroidism favors the progression of preneoplastic lesions to hepatocellular carcinoma in rats.

UNLABELLED: Thyroid hormone receptors (TRs) are ligand-dependent transcription factors that mediate most of the effects elicited by the thyroid hormone, 3,5,3'-L-triiodothyronine (T3). TRs have been implicated in tumorigenesis, although it is unclear whether they act as oncogenes or tumor suppressors, and at which stage of tumorigenesis their dysregulation occurs. Using the resistant-hepatocyte rat model (R-H model), we found down-regulation of TRß1 and TRα1 and their target genes in early preneoplastic lesions and hepatocellular carcinoma (HCCs), suggesting that a hypothyroid status favors the onset and progression of preneoplastic lesions to HCC. Notably, TRß1 and, to a lesser extent, TRα1 down-regulation was observed only in preneoplastic lesions positive for the progenitor cell marker, cytokeratin-19 (Krt-19) and characterized by a higher proliferative activity, compared to the Krt-19 negative ones. TRß1 down-regulation was observed also in the vast majority of the analyzed human HCCs, compared to the matched peritumorous liver or to normal liver. Hyperthyroidism induced by T3 treatment caused up-regulation of TRß1 and of its target genes in Krt-19(+) preneoplastic rat lesions and was associated with nodule regression. In HCC, TRß1 down-regulation was not the result of hypermethylation of its promoter, but was associated with an increased expression of TRß1-targeting microRNAs ([miR]-27a, -181a, and -204). An inverse correlation between TRß1 and miR-181a was also found in human cirrhotic peritumoral tissue, compared to normal liver. CONCLUSION: Down-regulation of TRs, especially TRß1, is an early and relevant event in liver cancer development and is species and etiology independent. The results also suggest that a hypothyroid status of preneoplastic lesions may contribute to their progression to HCC and that the reversion of this condition may represent a possible therapeutic goal to interfere with the development of this tumor.

Nrf2, but not ß-catenin, mutation represents an early event in rat hepatocarcinogenesis.

UNLABELLED: Hepatocellular carcinoma (HCC) develops through a multistage process, but the nature of the molecular changes associated with the different steps, the very early ones in particular, is largely unknown. Recently, dysregulation of the NRF2/KEAP1 pathway and mutations of these genes have been observed in experimental and human tumors, suggesting their possible role in cancer development. To assess whether Nrf2/Keap1 mutations are early or late events in HCC development, we investigated their frequency in the rat Resistant Hepatocyte model, consisting of the administration of diethylnitrosamine followed by a brief exposure to 2-acetylaminofluorene. This model enables the dissection of all stages of hepatocarcinogenesis. We found that Nrf2/Keap1 mutations were present in 71% of early preneoplastic lesions and in 78.6% and 59.3% of early and advanced HCCs, respectively. Mutations of Nrf2 were more frequent, missense, and located in the Nrf2-Keap1 binding region. Mutations of Keap1 occurred at a much lower frequency in both preneoplastic lesions and HCCs and were mutually exclusive with those of Nrf2. Functional in vitro and in vivo studies showed that Nrf2 silencing inhibited the ability of tumorigenic rat cells to grow in soft agar and to form tumors. Unlike Nrf2 mutations, those of Ctnnb1, which are frequent in human HCC, were a later event as they appeared only in fully advanced HCCs (18.5%). CONCLUSION: In the Resistant Hepatocyte model of hepatocarcinogenesis the onset of Nrf2 mutations is a very early event, likely essential for the clonal expansion of preneoplastic hepatocytes to HCC, while Ctnnb1 mutations occur only at very late stages. Moreover, functional experiments demonstrate that Nrf2 is an oncogene critical for HCC progression and development.

MicroRNA/gene profiling unveils early molecular changes and nuclear factor erythroid related factor 2 (NRF2) activation in a rat model recapitulating human hepatocellular carcinoma (HCC).

UNLABELLED: Studies on gene and/or microRNA (miRNA) dysregulation in the early stages of hepatocarcinogenesis are hampered by the difficulty of diagnosing early lesions in humans. Experimental models recapitulating human hepatocellular carcinoma (HCC) are then used to perform this analysis. We performed miRNA and gene expression profiling to characterize the molecular events involved in the multistep process of hepatocarcinogenesis in the resistant-hepatocyte rat model. A high percentage of dysregulated miRNAs/genes in HCC were similarly altered in early preneoplastic lesions positive for the stem/progenitor cell marker cytokeratin-19, indicating that several HCC-associated alterations occur from the very beginning of the carcinogenic process. Our analysis also identified miRNA/gene-target networks aberrantly activated at the initial stage of hepatocarcinogenesis. Activation of the nuclear factor erythroid related factor 2 (NRF2) pathway and up-regulation of the miR-200 family were among the most prominent changes. The relevance of these alterations in the development of HCC was confirmed by the observation that NRF2 silencing impaired while miR-200a overexpression promoted HCC cell proliferation in vitro. Moreover, T3-induced in vivo inhibition of the NRF2 pathway accompanied the regression of cytokeratin-19-positive nodules, suggesting that activation of this transcription factor contributes to the onset and progression of preneoplastic lesions towards malignancy. The finding that 78% of genes and 57% of dysregulated miRNAs in rat HCC have been previously associated with human HCC as well underlines the translational value of our results. CONCLUSION: This study indicates that most of the molecular changes found in HCC occur in the very early stages of hepatocarcinogenesis. Among these, the NRF2 pathway plays a relevant role and may represent a new therapeutic target.

YAP activation is an early event and a potential therapeutic target in liver cancer development.

BACKGROUND & AIMS: Although the growth suppressing Hippo pathway has been implicated in hepatocellular carcinoma (HCC) pathogenesis, it is unknown at which stage of hepatocarcinogenesis its dysregulation occurs. We investigated in rat and human preneoplastic lesions whether overexpression of the transcriptional co-activator Yes-associated protein (YAP) is an early event. METHODS: The experimental model used is the resistant-hepatocyte (R-H) rat model. Gene expression was determined by qRT-PCR or immunohistochemistry. Forward genetic experiments were performed in human HCC cells and in murine oval cells. RESULTS: All foci of preneoplastic hepatocytes, generated in rats 4weeks after diethylnitrosamine (DENA) treatment, displayed YAP accumulation. This was associated with down-regulation of the ß-TRCP ligase, known to mediate YAP degradation, and of microRNA-375, targeting YAP. YAP accumulation was paralleled by the up-regulation of its target genes. Increased YAP expression was also observed in human early dysplastic nodules and adenomas. Animal treatment with verteporfin (VP), which disrupts the formation of the YAP-TEAD complex, significantly reduced preneoplastic foci and oval cell proliferation. In vitro experiments confirmed that VP-mediated YAP inhibition impaired cell growth in HCC and oval cells; notably, oval cell transduction with wild type or active YAP conferred tumorigenic properties in vitro and in vivo. CONCLUSIONS: These results suggest that (i) YAP overexpression is an early event in rat and human liver tumourigenesis; (ii) it is critical for the clonal expansion of carcinogen-initiated hepatocytes and oval cells, and (iii) VP-induced disruption of the YAP-TEAD interaction may provide an important approach for the treatment of YAP-overexpressing cancers.

Sex difference in liver diseases: How preclinical models help to dissect the sex-related mechanisms sustaining NAFLD and hepatocellular carcinoma.

Only a few preclinical findings are confirmed in the clinic, posing a critical issue for clinical development. Therefore, identifying the best preclinical models can help to dissect molecular and mechanistic insights into liver disease pathogenesis while being clinically relevant. In this context, the sex relevance of most preclinical models has been only partially considered. This is particularly significant in NAFLD and HCC, which have a higher prevalence in men when compared to pre-menopause women but not to those in post-menopausal status, suggesting a role for sex hormones in the pathogenesis of the diseases. This review gathers the sex-relevant findings and the available preclinical models focusing on both in vitro and in vivo studies and discusses the potential implications and perspectives of introducing the sex effect in the selection of the best preclinical model. This is a critical aspect that would help to tailor personalized therapies based on sex.

Potential use of TG68 - A novel thyromimetic - for the treatment of non-alcoholic fatty liver (NAFLD)-associated hepatocarcinogenesis.

Introduction: Several lines of evidence suggest that the thyroid hormone signaling pathway is altered in patients with NAFLD and that pharmacological strategies to target the thyroid hormone/thyroid hormone nuclear receptor axis (TH/THR) in the liver may exert beneficial effects. In this study, we investigated the effect of TG68, a novel THRß agonist, on rat hepatic fat accumulation and NAFLD-associated hepatocarcinogenesis. Methods: Male rats given a single dose of diethylnitrosamine (DEN) and fed a high fat diet (HFD) were co-treated with different doses of TG68. Systemic and hepatic metabolic parameters, immunohistochemistry and hepatic gene expression were determined to assess the effect of TG68 on THRß activation. Results: Irrespectively of the dose, treatment with TG68 led to a significant reduction in liver weight, hepatic steatosis, circulating triglycerides, cholesterol and blood glucose. Importantly, a short exposure to TG68 caused regression of DEN-induced preneoplastic lesions associated with a differentiation program, as evidenced by a loss of neoplastic markers and reacquisition of markers of differentiated hepatocytes. Finally, while an equimolar dose of the THRß agonist Resmetirom reduced hepatic fat accumulation, it did not exert any antitumorigenic effect. Discussion: The use of this novel thyromimetic represents a promising therapeutic strategy for the treatment of NAFLD-associated hepatocarcinogenesis.

Diverse MicroRNAs-mRNA networks regulate the priming phase of mouse liver regeneration and of direct hyperplasia.

OBJECTIVES: Adult hepatocytes are quiescent cells that can be induced to proliferate in response to a reduction in liver mass (liver regeneration) or by agents endowed with mitogenic potency (primary hyperplasia). The latter condition is characterized by a more rapid entry of hepatocytes into the cell cycle, but the mechanisms responsible for the accelerated entry into the S phase are unknown. MATERIALS AND METHODS: Next generation sequencing and Illumina microarray were used to profile microRNA and mRNA expression in CD-1 mice livers 1, 3 and 6 h after 2/3 partial hepatectomy (PH) or a single dose of TCPOBOP, a ligand of the constitutive androstane receptor (CAR). Ingenuity pathway and DAVID analyses were performed to identify deregulated pathways. MultiMiR analysis was used to construct microRNA-mRNA networks. RESULTS: Following PH or TCPOBOP we identified 810 and 527 genes, and 102 and 10 miRNAs, respectively, differentially expressed. Only 20 genes and 8 microRNAs were shared by the two conditions. Many miRNAs targeting negative regulators of cell cycle were downregulated early after PH, concomitantly with increased expression of their target genes. On the contrary, negative regulators were not modified after TCPOBOP, but Ccnd1 targeting miRNAs, such as miR-106b-5p, were downregulated. CONCLUSIONS: While miRNAs targeting negative regulators of the cell cycle are downregulated after PH, TCPOBOP caused downregulation of miRNAs targeting genes required for cell cycle entry. The enhanced Ccnd1 expression may explain the more rapid entry into the S phase of mouse hepatocytes following TCPOBOP.

mRNA-miRNA networks identify metabolic pathways associated to the anti-tumorigenic effect of thyroid hormone on preneoplastic nodules and hepatocellular carcinoma.

Background: Thyroid hormones (THs) inhibit hepatocellular carcinoma (HCC) through different mechanisms. However, whether microRNAs play a role in the antitumorigenic effect of THs remains unknown. Methods: By next generation sequencing (NGS) we performed a comprehensive comparative miRNomic and transcriptomic analysis of rat hepatic preneoplastic lesions exposed or not to a short-term treatment with triiodothyronine (T3). The expression of the most deregulated miRs was also investigated in rat HCCs, and in human hepatoma cell lines, treated or not with T3. Results: Among miRs down-regulated in preneoplastic nodules following T3, co-expression networks revealed those targeting thyroid hormone receptor-ß (Thrß) and deiodinase1, and Oxidative Phosphorylation. On the other hand, miRs targeting members of the Nrf2 Oxidative Pathway, Glycolysis, Pentose Phosphate Pathway and Proline biosynthesis - all involved in the metabolic reprogramming displayed by preneoplastic lesions- were up-regulated. Notably, while the expression of most miRs deregulated in preneoplastic lesions was not altered in HCC or in hepatoma cells, miR-182, a miR known to target Dio1 and mitochondrial complexes, was down-deregulated by T3 treatment at all stages of hepatocarcinogenesis and in hepatocarcinoma cell lines. In support to the possible critical role of miR-182 in hepatocarcinogenesis, exogenous expression of this miR significantly impaired the inhibitory effect of T3 on the clonogenic growth capacity of human HCC cells. Conclusions: This work identified several miRNAs, so far never associated to T3. In addition, the precise definition of the miRNA-mRNA networks elicited by T3 treatment gained in this study may provide a better understanding of the key regulatory events underlying the inhibitory effect of T3 on HCC development. In this context, T3-induced down-regulation of miR-182 appears as a promising tool.

Nrf2 Mutation/Activation Is Dispensable for the Development of Chemically Induced Mouse HCC.

BACKGROUND & AIMS: Activation of the kelch-like ECH-associated protein 1 (Keap1)-nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway has been associated with metabolic reprogramming in many tumors, including hepatocellular carcinoma (HCC). However, the contribution of Nrf2 mutations in this process remains elusive. Here, we investigated the occurrence of Nrf2 mutations in distinct models of mouse hepatocarcinogenesis. METHODS: HCCs were generated by experimental protocols consisting of the following: (1) a single dose of diethylnitrosamine (DEN), followed by repeated treatments with the nuclear-receptor agonist 1,4-bis-[2-(3,5-dichloropyridyloxy)]benzene; (2) repeated treatments with 1,4-bis-[2-(3,5-dichloropyridyloxy)]benzene alone; (3) a single dose of DEN followed by exposure to a choline-deficient L-amino acid-defined diet; and (4) a single dose of DEN with no further treatment. All of these protocols led to HCC development within 28-42 weeks. Activation of the Keap1-Nrf2 pathway was investigated by analyzing the presence of Nrf2 gene mutations, and the expression of Nrf2 target genes. Metabolic reprogramming was assessed by evaluating the expression of genes involved in glycolysis, the pentose phosphate pathway, and glutaminolysis. RESULTS: No Nrf2 mutations were found in any of the models of hepatocarcinogenesis analyzed. Intriguingly, despite the described cooperation between ß-catenin and the Nrf2 pathway, we found no evidence of Nrf2 activation in both early dysplastic nodules and HCCs, characterized by the presence of up to 80%-90% ß-catenin mutations. No HCC metabolic reprogramming was observed either. CONCLUSIONS: These results show that, unlike rat hepatocarcinogenesis, Nrf2 mutations do not occur in 4 distinct models of chemically induced mouse HCC. Interestingly, in the same models, metabolic reprogramming also was minimal or absent, supporting the concept that Nrf2 activation is critical for the switch from oxidative to glycolytic metabolism.

The double-sided of human leukocyte antigen-G molecules in type 1 autoimmune hepatitis.

The immunomodulatory effects of HLA-G expression and its role in cancers, human liver infections and liver transplantation are well documented, but so far, there are only a few reports addressing autoimmune liver diseases, particularly autoimmune hepatitis (AIH). Method and materials: We analyzed the genetic and phenotypic characteristics of HLA-G in 205 type 1 AIH patients (AIH-1) and a population of 210 healthy controls from Sardinia (Italy). Results: Analysis of the HLA-G locus showed no substantial differences in allele frequencies between patients and the healthy control population. The HLA-G UTR-1 haplotype was the most prevalent in both AIH-1 patients and controls (40.24% and 34.29%). Strong linkage was found between the HLA-G UTR-1 haplotype and HLA-DRB1*03:01 in AIH-1 patients but not controls (D' = 0.92 vs D' = 0.50 respectively; P = 1.3x10-8). Soluble HLA-G (sHLA-G) levels were significantly lower in AIH-1 patients compared to controls [13.9 (11.6 - 17.4) U/mL vs 21.3 (16.5 - 27.8) U/mL; P = 0.011]. Twenty-four patients with mild or moderate inflammatory involvement, as assessed from liver biopsy, showed much higher sHLA-G levels compared to the 28 patients with severe liver inflammation [33.5 (23.6 - 44.8) U/mL vs 8.8 (6.1 - 14.5) U/mL; P = 0.003]. Finally, immunohistochemistry analysis of 52 liver biopsies from AIH-1 patients did not show expression of HLA-G molecules in the liver parenchyma. However, a percentage of 69.2% (36/52) revealed widespread expression of HLA-G both in the cytoplasm and the membrane of plasma cells labeled with anti-HLA-G monoclonal antibodies. Conclusion: This study highlights the positive immunomodulatory effect of HLA-G molecules on the clinical course of AIH-1 and how this improvement closely correlates with plasma levels of sHLA-G. However, our results open the debate on the ambiguous role of HLA-G molecules expressed by plasma cells, which are pathognomonic features of AIH-1.

Natural killer-cell immunoglobulin-like receptors trigger differences in immune response to SARS-CoV-2 infection.

BACKGROUND: The diversity in the clinical course of COVID-19 has been related to differences in innate and adaptative immune response mechanisms. Natural killer (NK) lymphocytes are critical protagonists of human host defense against viral infections. It would seem that reduced circulating levels of these cells have an impact on COVID-19 progression and severity. Their activity is strongly regulated by killer-cell immuno-globulin-like receptors (KIRs) expressed on the NK cell surface. The present study's focus was to investigate the impact of KIRs and their HLA Class I ligands on SARS-CoV-2 infection. METHODS: KIR gene frequencies, KIR haplotypes, KIR ligands and combinations of KIRs and their HLA Class I ligands were investigated in 396 Sardinian patients with SARS-CoV-2 infection. Comparisons were made between 2 groups of patients divided according to disease severity: 240 patients were symptomatic or paucisymptomatic (Group A), 156 hospitalized patients had severe disease (Group S). The immunogenetic characteristics of patients were also compared to a population group of 400 individuals from the same geographical areas. RESULTS: Substantial differences were obtained for KIR genes, KIR haplotypes and KIR-HLA ligand combinations when comparing patients of Group S to those of Group A. Patients in Group S had a statistically significant higher frequency of the KIR A/A haplotype compared to patients in Group A [34.6% vs 23.8%, OR = 1.7 (95% CI 1.1-2.6); P = 0.02, Pc = 0.04]. Moreover, the KIR2DS2/HLA C1 combination was poorly represented in the group of patients with severe symptoms compared to those of the asymptomatic-paucisymptomatic group [33.3% vs 50.0%, OR = 0.5 (95% CI 0.3-0.8), P = 0.001, Pc = 0.002]. Multivariate analysis confirmed that, regardless of the sex and age of the patients, the latter genetic variable correlated with a less severe disease course [ORM = 0.4 (95% CI 0.3-0.7), PM = 0.0005, PMC = 0.005]. CONCLUSIONS: The KIR2DS2/HLA C1 functional unit resulted to have a strong protective effect against the adverse outcomes of COVID-19. Combined to other well known factors such as advanced age, male sex and concomitant autoimmune diseases, this marker could prove to be highly informative of the disease course and thus enable the timely intervention needed to reduce the mortality associated with the severe forms of SARS-CoV-2 infection. However, larger studies in other populations as well as experimental functional studies will be needed to confirm our findings and further pursue the effect of KIR receptors on NK cell immune-mediated response to SARS-Cov-2 infection.

Thyroid hormone receptor ligands induce regression of rat preneoplastic liver lesions causing their reversion to a differentiated phenotype.

UNLABELLED: Triiodothyronine (T3), through interaction with its intracellular thyroid hormone receptors (TRs), influences various physiological functions, including metabolism, development, and growth. We investigated the effect of T3 and the selective TR-beta agonist GC-1 in two models of hepatocarcinogenesis. Preneoplastic lesions were induced in F-344 rats via a single dose of diethylnitrosamine, followed by a choline-deficient (CD) diet for 10 weeks. Rat subgroups were then fed the CD diet or a CD diet containing either 4 mg/kg T3 or 5 mg/kg GC-1 for another week. Rats fed a CD diet alone showed a large number (65/cm(2)) of preneoplastic lesions positive for the placental form of glutathione S-transferase (GSTP). Coadministration of T3 for the last week caused an almost complete disappearance of the foci (3/cm(2)). A reduction of GSTP-positive foci was also observed in rats fed a CD + GC-1 diet (28/cm(2) versus 75/cm(2) of rats fed a CD diet alone) in the absence of significant differences in labeling or apoptotic index of preneoplastic hepatocytes between the two groups. An antitumoral effect of GC-1 was also observed with the resistant hepatocyte model of hepatocarcinogenesis. Nodule regression was associated with a return to a fully differentiated phenotype, indicated by the loss of the fetal markers GSTP and gamma glutamyl transpeptidase, and reacquisition of the activity of glucose 6-phosphatase and adenosine triphosphatase, two enzymes expressed in normal hepatocytes. CONCLUSION: Our results indicate that activated TRs negatively influence the carcinogenic process through induction of a differentiation program of preneoplastic hepatocytes. The results also suggest that TRs could be a meaningful target in liver cancer therapy.

Animal Models: A Useful Tool to Unveil Metabolic Changes in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is one the most frequent and lethal human cancers. At present, no effective treatment for advanced HCC exist; therefore, the overall prognosis for HCC patients remains dismal. In recent years, a better knowledge of the signaling pathways involved in the regulation of HCC development and progression, has led to the identification of novel potential targets for therapeutic strategies. However, the obtained benefits from current therapeutic options are disappointing. Altered cancer metabolism has become a topic of renewed interest in the last decades, and it has been included among the core hallmarks of cancer. In the light of growing evidence for metabolic reprogramming in cancer, a wide number of experimental animal models have been exploited to study metabolic changes characterizing HCC development and progression and to further expand our knowledge of this tumor. In the present review, we discuss several rodent models of hepatocarcinogenesis, that contributed to elucidate the metabolic profile of HCC and the implications of these changes in modulating the aggressiveness of neoplastic cells. We also highlight the apparently contrasting results stemming from different animal models. Finally, we analyze whether these observations could be exploited to improve current therapeutic strategies for HCC.

Distinct Mechanisms Are Responsible for Nrf2-Keap1 Pathway Activation at Different Stages of Rat Hepatocarcinogenesis.

Activation of the Nrf2-Keap1 pathway, the main intracellular defense against environmental stress, has been observed in several human cancers, including hepatocellular carcinoma (HCC). Here, we assessed whether distinct mechanisms of activation may be involved at different stages of hepatocarcinogenesis. We adopted an experimental model consisting of treatment with diethylnitrosamine (DENA) followed by a choline-devoid methionine-deficient (CMD) diet for 4 months. The CMD diet was then replaced with a basal diet, and the animals were killed at 6, 10 or 13 months after DENA injection. Nrf2 activation occurred at early steps of hepatocarcinogenesis and persisted throughout the tumorigenic process. While Nrf2 mutations were extremely frequent at early steps (90%), their incidence diminished with the progression to malignancy (25%). Conversely, while p62 was almost undetectable in early nodules, its accumulation occurred in HCCs, suggesting that Nrf2 pathway activation at late stages is mainly due to Keap1 sequestration by p62. We demonstrate that, in a model of hepatocarcinogenesis resembling human non-alcoholic fatty liver disease, Nrf2 mutations are the earliest molecular changes responsible for the activation of the Nrf2-Keap1 pathway. The progressive loss of mutations associated with a concomitant p62 accumulation implies that distinct mechanisms are responsible for Nrf2-Keap1 pathway activation at different stages of hepatocarcinogenesis.