Aberrant dipeptidyl peptidase IV (DPP IV/CD26) expression in human hepatocellular carcinoma

Effect of transplanted cells with CD184 and CD26 expressions and reconstitution of CD3+ lymphocyte population on long-term survival after autologous hematopoietic stem cell transplantation for multiple myeloma

Autologous hematopoietic stem cell transplantation (auto-SCT) is the recommended treatment for responding patients with multiple myeloma (MM). However, we do not know the risk factors influencing long-term survival without progression after auto-SCT. Therefore, this prospective study aimed to investigate the influence of transplanted cells with cluster of differentiation (CD)184+ expression, CD26+ lymphocytes and monocytes, and reconstitution of CD3+ lymphocytes on overall survival (OS) and progression-free survival (PFS) after auto-SCT in MM. Forty-eight patients with MM underwent auto-SCT at our center from 2011 to 2013. The numbers of CD184+ cells, CD26+ lymphocytes, and CD26+ monocytes were measured in the harvested material. In addition, the number of lymphocyte subpopulations (CD3+ lymphocytes, helpers, suppressors, natural killer (NK), cytotoxic NK, and B lymphocytes) was measured in peripheral blood during regeneration after auto-SCT. Flow cytometry was performed in both cases. The median OS was 92 months. Our analysis revealed a statistically significant effect of the number of transplanted CD184+ cells on OS and a statistically significant correlation between PFS and the number of transplanted CD184+ cells and reconstitution of CD3+ lymphocytes. In conclusion, our study showed that the increasing numbers of transplanted CD184+ cells, CD26+ lymphocytes, and CD26+ monocytes augmented the risk of death.

Pathomechanism of Pruritus in Psoriasis and Atopic Dermatitis: Novel Approaches, Similarities and Differences

Pruritus is defined as an unpleasant sensation that elicits a desire to scratch. Nearly a third of the world's population may suffer from pruritus during their lifetime. This symptom is widely observed in numerous inflammatory skin diseases-e.g., approximately 70-90% of patients with psoriasis and almost every patient with atopic dermatitis suffer from pruritus. Although the pathogenesis of atopic dermatitis and psoriasis is different, the complex intricacies between several biochemical mediators, enzymes, and pathways seem to play a crucial role in both conditions. Despite the high prevalence of pruritus in the general population, the pathogenesis of this symptom in various conditions remains elusive. This review aims to summarize current knowledge about the pathogenesis of pruritus in psoriasis and atopic dermatitis. Each molecule involved in the pruritic pathway would merit a separate chapter or even an entire book, however, in the current review we have concentrated on some reports which we found crucial in the understanding of pruritus. However, the pathomechanism of pruritus is an extremely complex and intricate process. Moreover, many of these signaling pathways are currently undergoing detailed analysis or are still unexplained. As a result, it is currently difficult to take an objective view of how far we have come in elucidating the pathogenesis of pruritus in the described diseases. Nevertheless, considerable progress has been made in recent years.

Association Between DPP4 Inhibitor Use and the Incidence of Cirrhosis, ESRD, and Some Cancers in Patients With Diabetes

CONTEXT

There are relatively few data on noncardiovascular (non-CV) long-term clinical outcomes of dipeptidyl peptidase 4 inhibitor (DPP4i) treatment.

OBJECTIVE

We aimed to evaluate some non-CV effects of DPP4is in patients with diabetes.

METHODS

Based on data from the National Health Insurance Service database in Korea (2007-2018), we conducted 3 pairwise comparisons of metformin-combined antidiabetic therapies in adult patients with diabetes: DPP4is vs (1) all other oral antidiabetic agents, (2) sulfonylureas/glinides, and (3) thiazolidinediones (TZDs). Major outcomes were liver cirrhosis, end-stage renal disease (ESRD), and cancers in the liver, kidney, and pancreas. Adjusted hazard ratios (HRs) and 95% CIs for the outcomes were estimated using an adjusted Cox model.

RESULTS

Of the 747 124 patients included, 628 217 had received DPP4i therapy for a mean duration of 33.8 ± 25.0 months. Compared with TZD therapy, DPP4i therapy was associated with higher adjusted HRs [95% CIs] for liver cirrhosis (1.267 [1.108-1.449]), ESRD (1.596 [1.139-2.236]), liver cancer (1.117 [1.011-1.235]), and pancreatic cancer (1.158 [1.040-1.290]). Furthermore, apart from liver cirrhosis, a higher risk of each of these outcomes was associated with DPP4i use than with non-DPP4i use. The higher adjusted HRs associated with DPP4i use further increased when patients with long-term exposure to DPP4is were analyzed.

CONCLUSION

DPP4i therapy in patients with diabetes was associated with a higher risk of liver cirrhosis and cancer, ESRD, and pancreatic cancer than TZD therapy and, except for liver cirrhosis, the risk of these outcomes was greater with DPP4i treatment than with non-DPP4i treatment.

Effect of novel glucose lowering agents on non-alcoholic fatty liver disease: A systematic review and meta-analysis

BACKGROUND

The efficacy of novel glucose-lowering drugs in treating non-alcoholic fatty liver disease (NAFLD) in patients with and without type-2 diabetic patients (T2DM) remains unclear.

AIM

To conduct a meta-analysis to evaluate the efficacy of 3 novel glucose-lowering drug classes, namely glucagon-like peptide-1 receptor agonists (GLP-1RA), sodium-glucose co-transporter 2 (SGLT2) inhibitors, and dipeptidyl-peptidase-4 (DPP4) inhibitors on hepatic parameters: Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), Gamma-Glutamyl Transferase (GGT), Bilirubin, and FIB-4 (Fibrosis).

METHODS

MEDLINE was searched from inception through October 2021 for randomized placebo or active glucose-lowering drug-controlled trials. A random-effects model was used to pool the results. A p-value of less than or equal to 0.05 was considered significant. Results were presented as weighted mean differences (WMD) and corresponding 95% confidence intervals (CIs).

RESULTS

Our pooled analysis consisted of 40 studies. A significant reduction was seen in AST with SGLT2 inhibitors (WMD = -2.31 IU/L, 95%CI: -3.16 to -1.47 IU/L, P < 0.00001) and GLP-1RA (WMD = -3.29 IU/L, 95%CI: -5.98 to -0.61 IU/L, P = 0.02). Similarly, significant reduction was seen in ALT with SGLT2 inhibitors (WMD = -5.93 IU/L, 95%CI: -7.70 to -4.16 IU/L, P < 0.00001) and GLP-1RAs (WMD = -9.92 IU/L, 95%CI: -19.89 to 0.05 IU/L, P = 0.05). In contrast, DPP-4 inhibitors showed no significant reduction in AST (WMD = -3.20 IU/L, 95%CI: -11.13 to 4.73 IU/L, P = 0.43) or ALT (WMD = -4.81 IU/L, 95%CI: -15.83 to 6.21 IU/L, P = 0.39). A significant reduction in GGT was seen with SGLT2 inhibitors (WMD = -6.49 IU/L, 95%CI: -11.09 to -1.89 IU/L, P = 0.006) and GLP-1RAs (WMD = -12.38 IU/L, 95%CI: -15.69 to -9.07 IU/L, P < 0.00001). However, significant results were not observed with DPP-4 inhibitors (WMD = -0.92 IU/L, 95%CI: -5.80 to 3.96 IU/L, P = 0.71). There was a statistically significant reduction in FIB-4 index with SGLT2 inhibitors (WMD = -0.21, 95%CI: -0.40 to -0.03, P = 0.02) and GLP-1 RA (WMD = -0.15, 95%CI: -0.29 to 0.00, P = 0.05). Lastly, SGLT2 inhibitors led to a significant change in bilirubin levels (WMD = 2.03, 95%CI: 0.76 to 3.30, P = 0.002) while the change in bilirubin was not significant with GLP-1 agonists (WMD = -0.21, 95%CI: -1.09 to 0.66, P = 0.63) and DPP-4 inhibitors (WMD = 0.14, 95%CI: -1.55 to 1.83, P = 0.87).

CONCLUSION

SGLT2 inhibitors and GLP-1 agonists have a beneficial effect on hepatic parameters in patients with NAFLD. However, further research is needed to evaluate the effect of DPP-4 inhibitors on hepatic function properly.

Does DPP-IV Inhibition Offer New Avenues for Therapeutic Intervention in Malignant Disease?

Simple Summary

There is growing interest in identifying the effects of antidiabetic agents on cancer risk, progression, and anti-cancer treatment due to the long-term use of these medications and the inherently increased risk of malignancies in diabetic patients. Tumor development and progression are affected by multiple mediators in the tumor microenvironment, several of which may be proteolytically modified by the multifunctional protease dipeptidyl peptidase-IV (DPP-IV, CD26). Currently, low-molecular-weight DPP-IV inhibitors (gliptins) are used in patients with type 2 diabetes based on the observation that DPP-IV inhibition enhances insulin secretion by increasing the bioavailability of incretins. However, the DPP-IV-mediated cleavage of other biopeptides and chemokines is also prevented by gliptins. The potential utility of gliptins in other areas of medicine, including cancer, is therefore being evaluated. Here, we critically review the existing evidence on the role of DPP-IV inhibitors in cancer pathogenesis, their potential to be used in anti-cancer treatment, and the possible perils associated with this approach.

Abstract

Dipeptidyl peptidase IV (DPP-IV, CD26) is frequently dysregulated in cancer and plays an important role in regulating multiple bioactive peptides with the potential to influence cancer progression and the recruitment of immune cells. Therefore, it represents a potential contributing factor to cancer pathogenesis and an attractive therapeutic target. Specific DPP-IV inhibitors (gliptins) are currently used in patients with type 2 diabetes mellitus to promote insulin secretion by prolonging the activity of the incretins glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Nevertheless, the modulation of the bioavailability and function of other DPP-IV substrates, including chemokines, raises the possibility that the use of these orally administered drugs with favorable side-effect profiles might be extended beyond the treatment of hyperglycemia. In this review, we critically examine the possible utilization of DPP-IV inhibition in cancer prevention and various aspects of cancer treatment and discuss the potential perils associated with the inhibition of DPP-IV in cancer. The current literature is summarized regarding the possible chemopreventive and cytotoxic effects of gliptins and their potential utility in modulating the anti-tumor immune response, enhancing hematopoietic stem cell transplantation, preventing acute graft-versus-host disease, and alleviating the side-effects of conventional anti-tumor treatments.

Preliminary Study on the Sequencing of Whole Genomic Methylation and Transcriptome-Related Genes in Thyroid Carcinoma

Simple Summary

Epigenetic alterations are critical for tumor onset and development. DNA methylation is one of the most studied pathways concerning various types of cancer. A promising and exciting avenue of research is the discovery of biomarkers of early-stage malignancies for disease prevention and prognostic indicators following cancer treatment by examining the DNA methylation modification of relevant genes implicated in cancer development. We have made significant advances in the study of DNA methylation and thyroid cancer. This study is novel in that it distinguished methylation changes that occurred primarily in the gene body region of the aforementioned hypermethylated or hypomethylated thyroid cancer genes. Our findings imply that exposing whole-genome DNA methylation patterns and gene expression profiles in thyroid cancer provides new insight into the carcinogenesis of thyroid cancer, demonstrating that gene expression mediated by DNA methylation modifications may play a significant role in tumor growth.

Abstract

Thyroid carcinoma is the most prevalent endocrine cancer globally and the primary cause of cancer-related mortality. Epigenetic modifications are progressively being linked to metastasis. This study aimed to examine whole-genome DNA methylation patterns and the gene expression profiles in thyroid cancer tissue samples using a MethylationEPIC BeadChip (850K), RNA sequencing, and a targeted bisulfite sequencing assay. The results of the Illumina Infinium human methylation kit (850K) analyses identified differentially methylated CpG locations (DMPs) and differentially methylated CpG regions (DMRs) encompassing nearly the entire genome with high resolution and depth. Gene ontology and KEGG pathway analyses revealed that the genes associated with DMRs belonged to various domain-specific ontologies, including cell adhesion, molecule binding, and proliferation. The RNA-Seq study found 1627 differentially expressed genes, 1174 of which that were up-regulated and 453 of which that were down-regulated. The targeted bisulfite sequencing assay revealed that CHST2, DPP4, DUSP6, ITGA2, SLC1A5, TIAM1, TNIK, and ABTB2 methylation levels were dramatically lowered in thyroid cancer patients when compared to the controls, but GALNTL6, HTR7, SPOCD1, and GRM5 methylation levels were significantly raised. Our study revealed that the whole-genome DNA methylation patterns and gene expression profiles in thyroid cancer shed new light on the tumorigenesis of thyroid cancer.

CD26/DPP4 as a Therapeutic Target in Nonalcoholic Steatohepatitis Associated Hepatocellular Carcinoma

Simple Summary

CD26/DPP4 has been reported to attenuate anticancer immunity via chemokine cleavage and to promote insulin resistance and inflammation in the liver and/or adipose tissue via dysregulation of macrophage M1/M2 polarization. These results suggest the promotive roles of CD26/DPP4 especially in nonalcoholic steatohepatitis (NASH) associated hepatocellular carcinoma (HCC). In this review, we discuss the biological roles of CD26/DPP4 in the development and progression of NASH associated HCC and the potential of DPP4 inhibitors as therapeutic agents for HCC.

Abstract

Hepatocellular carcinoma (HCC) is generally considered an “immune-cold” cancer since T cells are not observed abundantly in HCC tumor tissue. Combination therapy with immune checkpoint inhibitors and vascular endothelial growth factor (VEGF) inhibitors is currently recognized as a first-line systemic treatment for advanced-stage HCC. Immunologically, immune checkpoint inhibitors influence the recognition of cancer cells by T cells, and VEGF inhibitors influence the infiltration of T cells into tumors. However, no drugs that facilitate the trafficking of T cells toward tumors have been developed. Chemokines are promising agents that activate T cell trafficking. On the other hand, metabolic factors such as obesity and insulin resistance are considered risk factors for HCC development. CD26/dipeptidyl peptidase 4 (DPP4) functions as a serine protease, selectively cleaving polypeptides with a proline or alanine at the penultimate N-terminal position, such as chemokines. Recently, CD26/DPP4 has been reported to attenuate anticancer immunity via chemokine cleavage and to promote insulin resistance and inflammation in the liver and/or adipose tissue via dysregulation of macrophage M1/M2 polarization. In this review, we discuss the promotive roles of CD26/DPP4 in HCC development and progression and the potential of DPP4 inhibitors as therapeutic agents for HCC.

Potential Effect of DPP-4 Inhibitors Towards Hepatic Diseases and Associated Glucose Intolerance

Dipeptidyl-peptidase-4 (DPP-4) is an enzyme having various properties and physiological roles in lipid accumulation, resistance to anticancer agents, and immune stimulation. DPP-4 includes membrane-bound peptidases and is a kind of enzyme that cleaves alanine or proline-containing peptides such as incretins, chemokines, and appetite-suppressing hormones (neuropeptide) at their N-terminal dipeptides. DPP-4 plays a role in the final breakdown of peptides produced by other endo and exo-peptidases from nutritious proteins and their absorption in these tissues. DPP-4 enzyme activity has different modes of action on glucose metabolism, hunger regulation, gastrointestinal motility, immune system function, inflammation, and pain regulation. According to the literature survey, as DPP-4 levels increase in individuals with liver conditions, up-regulation of hepatic DPP-4 expression is likely to be the cause of glucose intolerance or insulin resistance. This review majorly focuses on the cleavage of alanine or proline-containing peptides such as incretins by the DPP-4 and its resulting conditions like glucose intolerance and cause of DPP-4 level elevation due to some liver conditions. Thus, we have discussed the various effects of DPP-4 on the liver diseases like hepatitis C, non-alcoholic fatty liver, hepatic regeneration and stem cell, hepatocellular carcinoma, and the impact of elevated DPP-4 levels in association with liver diseases as a cause of glucose intolerance and their treatment drug of choices. In addition, the effect of DPP-4 inhibitors on obesity and their negative aspects are also discussed in brief.

Saxagliptin defers thioacetamide-induced hepatocarcinogenesis in rats: A novel suppressive impact on Wnt/Hedgehog/Notch1 signaling

AIM

Hepatocellular carcinoma (HCC) is a highly invasive form of hepatic cancer. It is a highly intricate disease with multiple pathophysiological mechanisms underlying its pathogenesis.

MATERIALS AND METHODS

The results of the current investigation shed light on the ability of saxagliptin (SAXA) (12.5 mg/kg) to defer HCC progression in an experimental model of thioacetamide (TAA)-induced hepatocarcinogenesis.

RESULTS

SAXA administration improved liver function biomarkers, with a concomitant histopathological recovery. Mechanistically, the observed hepatoprotective impact was associated with significant suppression of the hepatic content of Wnt3a, β-catenin, Notch1, Smo, and Gli2 and enhanced expression of GSK 3β. Nevertheless, the hepatic expression of PCNA, P53, and cyclin D1 was significantly enhanced, with a parallel increase in the tumor expression of caspase-3. Thus, it appears that SAXA significantly enhanced tumor apoptosis, with concomitant suppression of HCC proliferation.

CONCLUSION

SAXA deferred experimentally-induced HCC via suppressing Wnt/Hedgehog/Notch1 Signaling, with enhanced tumor apoptosis and suppressed proliferation.

Serum levels of soluble dipeptidyl peptidase-4 in type 2 diabetes are associated with severity of liver fibrosis evaluated by transient elastography (FibroScan) and the FAST (FibroScan-AST) score, a novel index of non-alcoholic steatohepatitis with significant fibrosis

AIM

To investigate the relationship in people with type 2 diabetes between serum soluble dipeptidyl peptidase-4 (sDDP-4) and degree of liver fibrosis assessed as the liver stiffness measurement (LSM) and FAST (FibroScan-AST) score, both of which were measured by transient elastography (FibroScan).

SUBJECTS AND METHODS

In this cross-sectional study, we examined 115 patients with type 2 diabetes. With transient elastography (FibroScan), we assessed the controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) as measures of hepatic steatosis and liver fibrosis, respectively. We calculated the FAST score, which identifies progressive non-alcoholic steatohepatitis (NASH), from CAP, LSM, and the serum aspartate aminotransferase level. Significant hepatic steatosis was defined as CAP ≥280 dB/m; and significant liver fibrosis, as LSM ≥ 8.0 kPa. LSM was divided into 3 severity levels: significant fibrosis (8.0 to <9.7 kPa); advanced fibrosis, (9.7 to <13.0 kPa); and liver cirrhosis (≥ 13.0 kPa).

RESULTS

Serum sDPP-4 correlated positively with liver enzymes, CAP, LSM, and FAST score. Multivariate analysis showed that LSM remained to be an independent factor for serum sDDP-4. Serum sDPP-4 was significantly higher in patients with LSM ≥ 8.0 kPa than in those with LSM <8.0 kPa and was significantly elevated in patients who are at risk for non-alcoholic steatohepatitis (NASH) with fibrosis (FAST score ≥ 035 or 0.67). Patients with both hepatic steatosis and liver fibrosis had the highest serum sDPP-4.

CONCLUSION

Serum sDPP-4 was strongly associated with severity of liver fibrosis evaluated by LSM and the FAST score and was markedly elevated in diabetic patients with LSM ≥ 13.0 kPa indicating probable cirrhosis.

Vildagliptin, a dipeptidyl peptidase-4 inhibitor, reduces betel-nut induced carcinogenesis in female mice

AIM

Betel-nut, a popular masticatory among Southeast Asian populations is a class I carcinogen, previously associated with dyslipidemia and aberrant lipid metabolism, and is reported to be used more frequently by females, than males. This study investigates the potential of repurposing the anti-diabetic drug, vildagliptin, a dipeptidyl peptidase-4 inhibitor, for alleviating the oncogenic condition in female Swiss Albino mice administered an aqueous extract of betel-nut (AEBN) orally (2 mg ml^-1) for 24 weeks.

MAIN METHODS

Tissues were investigated by histopathological, immunohistochemical and apoptosis assays. Biochemical analyses of oxidative stress markers and lipid profile were performed using different tissues and sera. The expressions of different proteins involved in lipid metabolism and oncogenic pathways were evaluated by Western blotting.

KEY FINDINGS

AEBN induced carcinogenesis primarily in the liver by significantly impairing AMPK signaling, inducing oxidative stress, activating Akt/mTOR signaling, increasing Ki-67 immunoreactivity and cyclin D1 expression, and significantly diminishing apoptosis. Co-administration of AEBN with vildagliptin (10 mg kg^-1 body weight) for 8 weeks reduced liver dysplasia, and significantly decreased free palmitic acid, increased free oleic acid, normalized lipid profile, decreased oxidative stress, cyclin D1 expression, Ki-67 immunoreactivity, and Bcl2 expression, and increased the ratio of apoptotic/non-apoptotic cells. Mechanistically, vildagliptin elicited these physiological and molecular alterations by restoring normal AMPK signaling and reducing the cellular expressions of FASN and HMGCR, restoring AMPK-dependent phosphorylation of p53 at Ser-15 and reducing Akt/mTOR signaling.

SIGNIFICANCE

These results indicate that vildagliptin may alleviate betel-nut induced carcinogenesis in the liver of female mice.

Clinical implications, diagnosis, and management of diabetes in patients with chronic liver diseases

Diabetes mellitus (DM) negatively affects the development and progression of chronic liver diseases (CLD) of various etiologies. Concurrent DM and CLD are also associated with worse clinical outcomes with respect to mortality, the occurrence of hepatic decompensation, and the development of hepatocellular carcinoma (HCC). Unfortunately, early diagnosis and optimal treatment of DM can be challenging, due to the lack of established clinical guidelines as well as the medical complexity of this patient population. We conducted an exploratory review of relevant literature to provide an up-to-date review for internists and hepatologists caring for this patient population. We reviewed the epidemiological and pathophysiological associations between DM and CLD, the impact of insulin resistance on the progression and manifestations of CLD, the pathogenesis of hepatogenic diabetes, as well as the practical challenges in diagnosis and monitoring of DM in this patient population. We also reviewed the latest clinical evidence on various pharmacological antihyperglycemic therapies with an emphasis on liver disease-related clinical outcomes. Finally, we proposed an algorithm for managing DM in patients with CLD and discussed the clinical and research questions that remain to be addressed.

Soluble cluster of differentiation 26/soluble dipeptidyl peptidase-4 and glypican-3 are promising serum biomarkers for the early detection of Hepatitis C virus related hepatocellular carcinoma in Egyptians

BACKGROUND AND STUDY AIMS

Many patients are diagnosed with hepatocellular carcinoma (HCC) in the late stage when it is already untreatable. Therefore, there is an increased need for sensitive biomarkers to detect HCC at an earlier stage in high risk patients with hepatitis C virus (HCV)-induced cirrhosis. This study aimed to evaluate the diagnostic performance of soluble cluster of differentiation 26/dipeptidyl peptidase 4 (sCD26/sDPP4) and glypican-3 (GPC3) as serum biomarkers for the early detection of HCV related HCC and compare it with that of the conventional tumor marker serum alpha fetoprotein (AFP).

PATIENTS AND METHODS

The study included 80 participants, 30 patients diagnosed with HCV infection without HCC (HCV group), 30 patients diagnosed with HCV- related HCC (HCV group), and 20 healthy volunteers (control group). The serum levels of GPC3 and sCD26 were measured using specific enzyme linked immunosorbant assay (ELISA) kits, whereas AFP levels were determined using chemiluminescence.

RESULTS

The serum levels of both sCD26 and GPC3 were found to be significantly higher in patients with early-stage HCC than in the HCV group, (1450 and 1.16 ng/mL, respectively). sCD26 at a cutoff value of > 1000 ng/ml, showed a high sensitivity (83.3%) and 63.3% specificity with an area under curve (AUC) of 0.811 and a 95% confidence interval (CI) of (0.682-0.94). While, the combination of GPC3 and sCD26 exhibited the best diagnostic performance for early-stage-HCC because it increased the sensitivity and specificity (85% and 93.3% respectively), with an AUC of 0.986 and a 95% CI of (0.899-1.00) compared to sCD26 alone.

CONCLUSION

We conclude that serum sCD26 could be a sensitive biomarker for the early detection of HCC among HCV patients. Moreover, the combination of sCD26 and GPC3 increases both the sensitivity and specificity for the early detection of HCV related HCC compared with AFP and could help in the monitoring of HCC in high risk patients with HCV induced cirrhosis.

Vital members in the gut microbiotas altered by two probiotic Bifidobacterium strains against liver damage in rats

Background

Probiotics are effective to rectify the imbalanced gut microbiota in the diseased cohorts. Two Bifidobacterium strains (LI09 and LI10) were found to alleviate D-galactosamine-induced liver damage (LD) in rats in our previous work. A series of bioinformatic and statistical analyses were performed to determine the vital bacteria in the gut microbiotas altered by the LI09 or LI10 in rats.

Results

Two groups of representative phylotypes could distinguish the gut microbiotas of LI09 or LI10 groups from the other groups. Among them, OTU170_Porphyromonadaceae acted as a gatekeeper in LI09 group, while OTU12_Bacteroides was determined with multiple correlations in the gut network of LI10 group. Multiple reduced OTUs associated with LC and increased OTUs associated with health were determined in LI09 or LI10 groups, among which, increased OTU51_Barnesiella and reduced OTU99_Barnesiella could be associated with the protective effects of both the two probiotics. The gut microbiotas in LI09, LI10 and positive control groups were clustered into three clusters, i.e., Cluster_1_Microbiota, Cluster_2_Microbiota and Cluster_3_Microbiota, by Partition Around Medoids clustering analysis. Cluster_2_Microbiota was determined at least dysbiotic status due to its greatest LD dysbiosis ratio, lowest levels of liver function variables and plasma cytokines compared with the two other clustered microbiotas, suggesting the treated rats in Cluster_2 were at better health status.

Conclusion

Our findings suggest that OTU170_Porphyromonadaceae and OTU12_Bacteroides are vital in the gut microbiotas altered by LI09 and LI10. Characteristics of the LD cohorts treated by LI09 or LI10 at different gut microbial colonization states could help monitor the cohorts’ health status.

Transplantation of fetal liver tissue coated by ultra-purified alginate gel over liver improves hepatic function in the cirrhosis rat model

In this study, we used a new coating agent, that is, ultra-purified alginate gel (UPAL), for fetal liver tissue transplantation. This study aims to compare the effect of UPAL with the effect of other coating agents on improving the effect of fetal liver tissue transplantation in a liver cirrhosis rat model. Prior to the transplantation of wild-type ED14 fetal liver tissues, various coating agents were separately applied on the liver surface of rats with cirrhosis. Then, we compared the engraftment area, engraftment rate and liver function level of these rats. As a result, coating the liver surface of a cirrhosis rat with UPAL obtained the best effect in terms of engraftment area and engraftment rate of the transplanted liver tissue and in the recovery of liver function compared with control group. Therefore, UPAL coating may serve as a novel strategy for liver organoid transplantation.

Effects of a DPP4 Inhibitor on Progression of NASH-related HCC and the p62/ Keap1/Nrf2-Pentose Phosphate Pathway in a Mouse Model

BACKGROUND AND AIMS

Diabetes mellitus is a risk factor for hepatocellular carcinoma (HCC) in patients with nonalcoholic steatohepatitis (NASH). Dipeptidyl peptidase-4 inhibitor (DPP4i), an antidiabetic agent, is reported to affect cell proliferation. We aimed to investigate the effects of DPP4i on the progression of NASH-related HCC and its metabolic pathway in a mouse model.

METHODS

A mouse model of NASH-related HCC was used in this study. Eight-week-old mice were administered either DPP4i (sitagliptin 30 mg/kg/day; DPP4i group; n = 8) or distilled water (control group; n = 8) for 10 weeks. Then, HCC progression was evaluated by computed tomography. Changes in metabolites of HCC tissue were analyzed by metabolomic analysis. The localization and expression of p62, Keap1, Nrf2, and MCM7 were evaluated by immunostaining and immunoblotting, respectively.

RESULTS

The number and volume of HCC were significantly lower in the DPP4i group than in the control group (1.8 ± 1.2 vs. 4.5 ± 1.7/liver, p < 0.01; 11.2 ± 20.8 vs. 37.5 ± 72.5 mm³/tumor, p < 0.05). Metabolome analysis revealed that DPP4i significantly increased 6-phosphogluconic acid and ribose 5-phosphate levels and decreased the AMP-to-adenine and GMP-to-guanine ratios (AMP-to-adenine ratio 0.7 ± 0.2 vs. 2.0 ± 1.2, p < 0.01; GMP-to-guanine ratio 0.6 ± 0.3 vs. 1.5 ± 0.7, p < 0.01). Immunostaining showed that p62 was localized in the cytoplasm of HCC in the DPP4i group, while p62 was localized in the nucleus of HCC in the control group. Keap1, Nrf2, and MCM7 expression decreased significantly in the DPP4i group compared to that in the control group.

CONCLUSIONS

We demonstrated that DDP4i prevented the progression of NASH-related HCC in a mouse model. Furthermore, metabolome analysis revealed that DDP4i downregulated the pentose phosphate pathway with suppression of the p62/Keap1/Nrf2 pathway. Thus, DDP4i may prevent tumor progression through inhibition of metabolic reprogramming in NASH-related HCC.

Evidence of Amniotic Epithelial Cell Differentiation toward Hepatic Sinusoidal Endothelial Cells

Amniotic epithelial cells (AECs) represent a useful and noncontroversial source for liver-based regenerative medicine, as they can differentiate into hepatocytes upon transplantation into the liver. However, the possibility that AECs can differentiate into other liver cell types, such as hepatic sinusoidal endothelial cells (HSECs), has never been assessed. In order to test this hypothesis, rat- and human-derived AECs (rAECs and hAECs, respectively) were subjected to endothelial cell tube formation assay in vitro. Moreover, to evaluate differentiation in vivo, the retrorsine (RS) model of liver repopulation was used. Pyrrolizidine alkaloids (including RS) are known to target both hepatocytes and endothelial cells, inducing cell enlargement and inhibition of cell cycle progression. rAECs and hAECs were able to form capillary-like structures when cultured under proangiogenic conditions. For in vivo experiments, rAECs were obtained from dipeptidyl peptidase type IV (DPP-IV, CD26) donors and were transplanted into the liver of recipient CD26 negative animals pretreated with RS. rAEC-derived cells were engrafted in between hepatocytes and resembled HSECs as assessed by morphological analysis and the pattern of expression of CD26. Donor-derived CD26⁺ cells coexpressed HSEC markers RECA-1 and SE-1, while they lacked expression of typical hepatocyte markers (i.e., cytochrome P450, hepatocyte nuclear factor 4α). As such, these results provide the first evidence that AECs can respond to proangiogenic signals in vitro and differentiate into HSECs in vivo. Furthermore, they support the conclusion that AECs possesses great plasticity and represents a promising tool in the field of regenerative medicine both in the liver and in other organs.

Lymphocytes are a major source of circulating soluble dipeptidyl peptidase 4

Dipeptidyl peptidase 4 (DPP4, CD26) is a serine protease that is expressed constitutively by many haematopoietic and non-haematopoietic tissues. It exists as a membrane-associated protein, as well as in an active, soluble form (herein called sDPP4), present at high concentrations in bodily fluids. Despite the proposed use of sDPP4 as a biomarker for multiple diseases, its cellular sources are not well defined. Here, we report that individuals with congenital lymphocyte immunodeficiency had markedly lower serum concentrations of sDPP4, which were restored upon successful treatment and restoration of lymphocyte haematopoiesis. Using irradiated lymphopenic mice and wild-type to Dpp4-/- reciprocal bone marrow chimeric animals, we found that haematopoietic cells were a major source of circulating sDPP4. Furthermore, activation of human and mouse T lymphocytes resulted in increased sDPP4, providing a mechanistic link between immune system activation and sDPP4 concentration. Finally, we observed that acute viral infection induced a transient increase in sDPP4, which correlated with the expansion of antigen-specific CD8+ T cell responses. Our study demonstrates that sDPP4 concentrations are determined by the frequency and activation state of lymphocyte populations. Insights from these studies will support the use of sDPP4 concentration as a biomarker for inflammatory and infectious diseases.

Systemic DPP4 activity is reduced during primary HIV-1 infection and is associated with intestinal RORC+ CD4+ cell levels: a surrogate marker candidate of HIV-induced intestinal damage

INTRODUCTION

Combined anti-retroviral therapy (cART) transformed HIV-1 from a deadly disease into a chronic infection, but does not cure HIV infection. It also does not fully restore HIV-induced gut damage unless administered extremely early after infection. Additional biomarkers are needed to evaluate the capacity of therapies aimed at HIV remission/cure to restore HIV-induced intestinal immune damage and limit chronic inflammation. Herein, we aimed to identify a systemic surrogate marker whose levels would reflect gut immune damage such as intestinal Th17 cell loss starting from primary HIV-1 infection.

METHODS

Biomarker discovery approaches were performed in four independent cohorts, covering HIV-1 primary and chronic infection in 496 naïve or cART-treated patients (Amsterdam cohort (ACS), ANRS PRIMO, COPANA and CODEX cohorts). The concentration and activity of soluble Dipeptidylpeptidase 4 (sDPP4) were quantified in the blood from these patients, including pre- and post-infection samples in the ACS cohort. For quantification of DPP4 in the gut, we utilized two non-human primate models, representing pathogenic (macaque) and non-pathogenic (African green monkey) SIV infection. Four gut compartments were analysed in each animal model (ileum, jejunum, colon and rectum) for quantification of DPP4, RORC and TBX21 gene expression in sorted CD4+ cells. To analyse if sDPP4 levels increase when Th17 cells were restored, we quantified sDPP4 in plasma from SIV-infected macaques treated with IL-21.

RESULTS

We showed that sDPP4 levels were strongly decreased in primary HIV-1 infection. Strikingly, sDPP4 levels in primary HIV-1 infection predicted time to AIDS. They were not increased by cART in chronic HIV-1 infection (median 36 months on cART). In the gut of SIV-infected non-human primates, DPP4 mRNA was higher in CD4+ than CD4- leucocytes. DPP4 specifically correlated with RORC expression, a Th17 marker, in CD4+ cells from the intestine. We further demonstrated that sDPP4 activity levels were increased in animals treated with IL-21 and that this increase was associated with restoration of the Th17 compartment and reduced inflammation. Furthermore, DPP4 mRNA levels in small intestine CD4+ cells positively correlated with circulating DPP4 activity.

CONCLUSION

These data provide evidence that blood sDPP4 levels could be useful as a correlate for HIV-induced intestinal damage.

Targeting the Adenosinergic Axis in Chronic Lymphocytic Leukemia: A Way to Disrupt the Tumor Niche?

Targeting adenosine triphosphate (ATP) metabolism and adenosinergic signaling in cancer is gaining momentum, as increasing evidence is showing their relevance in tumor immunology and biology. Chronic lymphocytic leukemia (CLL) results from the expansion of a population of mature B cells that progressively occupies the bone marrow (BM), the blood, and peripheral lymphoid organs. Notwithstanding significant progress in the treatment of these patients, the cure remains an unmet clinical need, suggesting that novel drugs or drug combinations are needed. A unique feature of CLL is its reliance on micro-environmental signals for proliferation and cell survival. We and others have shown that the lymphoid niche, an area of intense interactions between leukemic and bystander non-tumor cells, is a typically hypoxic environment. Here adenosine is generated by leukemic cells, as well as by cells of myeloid origin, acting through autocrine and paracrine mechanisms, ultimately affecting tumor growth, limiting drug responses, and skewing the immune cells towards a tolerant phenotype. Hence, understanding the mechanisms through which this complex network of enzymes, receptors, and metabolites functions in CLL, will pave the way to the use of pharmacological agents targeting the system, which, in combination with drugs targeting leukemic cells, may get us one step closer to curing these patients.

Chronic activation profile of circulating CD8+ T cells in Sézary syndrome

Sézary syndrome (SS) is a leukemic variant of cutaneous T cell lymphoma (CTCL), and the neoplastic CD4+ T cells of SS patients undergo intense clonal proliferation. Although Sézary cells have been studied extensively, studies on adaptive immunity regarding CD8+T cells are scarce. This study aimed to investigate activation marker expression in CD8+ T cells according to the differentiation stages and IL-7/IL7Rα axis responses of patients with SS. Moreover, this study aimed to verify the soluble forms of CD38, sCD127 and IL-7 in serum. Although the SS patients of our cohort had reduced numbers of CD8+ T cells, they exhibited higher percentages of CD8+CD38+ T cells, mainly effector/memory CD8+ T cells, than the control group. In contrast, down-regulated expression of the activation markers CD127/IL-7R and CD26 was found in the CD8+ T cells of SS patients. High serum levels of sCD38 and sCD127 and scarce serum levels of IL-7 were detected, emphasizing the immune activation status of SS patients. Moreover, CD8+ T cells from SS patients exhibited IL-7 unresponsiveness to STAT5 phosphorylation and Bcl-2 expression, and IL-7 priming partially restored IFNγ production. Our findings showed a chronic activation profile of CD8+ T cells, as an attenuated cytotoxic profile and impaired IL-7 responsiveness was observed, suggesting chronic activation status of CD8+ T cells in SS patients.

Combination of Vildagliptin and Pioglitazone in Experimental Type 2 Diabetes in Male Rats

Preclinical Research The majority of studies on vildagliptin and pioglitazone have focused on their combination in glycemic control. The aim of the present study was to investigate their effects in combination on (i) hyperglycemia-induced oxidative stress and inflammation and (ii) on organs involved in the pathophysiology of diabetes, pancreas, kidney and liver. Type 2 diabetes was induced using low-dose streptozotocin in male Wistar rats. Diabetic rats were treated for 4 weeks, with vildagliptin (10 mg/kg/day), pioglitazone (10 mg/kg/day) and their combination. Diabetic rats showed elevated fasting serum glucose, fasting serum insulin, serum transaminases together with a deleterious lipid profile and elevated serum creatinine and urea concentrations. Serum levels of the inflammatory markers tumor necrosis factor-α (TNF-α) and nitrite/nitrate were also elevated compared to normal rats. Oxidative stress was manifested by lowered hepatic reduced glutathione (GSH) and increased malondialdehyde (MDA) levels. Pancreatic sections from diabetic rats showed degenerated islets with poorly maintained architecture that was prevented by drug treatment. Pioglitazone was generally more effective than vildagliptin in the studied parameters except for the lipid profile where the effect of both drugs was comparable and for the liver enzymes and renal parameters where vildagliptin was more effective. The combination of vildagliptin and pioglitazone produced superior effects than either drug alone. Drug Dev Res 77 : 251-257, 2016. © 2016 Wiley Periodicals, Inc.

DPP-4 inhibitors in diabetic complications: role of DPP-4 beyond glucose control

Dipeptidyl peptidase-4 (DPP-4) inhibitors (gliptins) are an emerging class of antidiabetic drugs that constitutes approximately fifty percent of the market share of the oral hypoglycemic drugs. Its mechanism of action for lowering blood glucose is essentially via inhibition of the rapid degradation of incretin hormones, such as glucagon-like peptide (GLP)-1 and gastric inhibitory polypeptide (GIP), thus the plasma concentration of GLP-1 increases, which promotes insulin secretion from the pancreatic β cells and suppresses glucagon secretion from the α cells. In addition to the direct actions on the pancreas, GLP-1 exhibits diverse actions on different tissues through its action on GLP-1 receptor, which is expressed ubiquitously. Moreover, DPP-4 has multiple substrates besides GLP-1 and GIP, including cytokines, chemokines, neuropeptides, and growth factors, which are involved in many pathophysiological conditions. Recently, it was suggested that DPP-4 is a new adipokine secreted from the adipose tissue, which plays an important role in the regulation of the endocrine function in obesity-associated type 2 diabetes. Consequently, DPP-4 inhibitors have been reported to exhibit cytoprotective functions against various diabetic complications affecting the liver, heart, kidneys, retina, and neurons. This review outlines the current understanding of the effect of DPP-4 inhibitors on the complications associated with type 2 diabetes, such as liver steatosis and inflammation, dysfunction of the adipose tissue and pancreas, cardiovascular diseases, nephropathy, and neuropathy in preclinical and clinical studies.

Hepatocellular carcinoma: Mouse models and the potential roles of proteases

Primary liver cancer is the second most common cause of mortality from cancer. The most common models of hepatocellular carcinoma, which use a chemical and/or metabolic insult, xenograft, or genetic manipulation, are discussed in this review. In the tumour microenvironment lymphocytes, fibroblasts, endothelial cells and antigen presenting cells are important determinants of cell fate. These cells make a range of proteases that modify the biological activity of other proteins, particularly extracellular matrix proteins that alter cell migration of tumour cells, fibroblasts and leucocytes, and chemokines that alter leucocyte migration. The DPP4 family of post-proline peptidase enzymes modifies cell movement and the activities of many bioactive molecules including growth factors and chemokines.

Dipeptidyl peptidase 4 promotes epithelial cell transformation and breast tumourigenesis via induction of PIN1 gene expression

BACKGROUND AND PURPOSE

Dipeptidyl peptidase 4 (DPP4) is an aminopeptidase that is widely expressed in different cell types. Recent studies suggested that DPP4 plays an important role in tumour progression in several human malignancies. Here we have examined the mechanisms by which up-regulation of DPP4 expression causes epithelial transformation and mammary tumourigenesis.

EXPERIMENTAL APPROACH

Expression of DPP4 and the peptidylprolyl cis/trans isomerase, NIMA-interacting 1 (PIN1), and the cytotoxic effects of combined treatment with sitagliptin and juglone were investigated by immunohistochemistry, immunoblotting, real-time PCR, TUNEL and soft agar assays, using MCF7 cells. The effects of sitagliptin on tumour development in vivo were studied in the syngeneic 4T1 metastatic breast cancer model.

KEY RESULTS

Activity of the transcription factor E2F1 induced by EGF was enhanced by DPP4, thus increasing PIN1 expression. Furthermore, DPP4 enhanced MEK/ERK and JNK/c-Jun signalling induced by EGF, inducing AP-1 activity and epithelial cell transformation. In contrast, DPP4 silencing or DPP4 inhibition in MCF7 cells inhibited PIN1 expression via E2F1 activity induced by EGF, decreasing colony formation and inducing DNA fragmentation. In the syngeneic 4T1 metastatic breast cancer model, DPP4 overexpression increased tumour development, whereas treatment with sitagliptin and/or juglone suppressed it. Consistent with these observations, DPP4 levels were positively correlated with PIN1 expression in human breast cancer.

CONCLUSIONS AND IMPLICATIONS

DPP4 promoted EGF-induced epithelial cell transformation and mammary tumourigenesis via induction of PIN1 expression, suggesting that sitagliptin targeting of DPP4 could be a treatment strategy in patients with breast cancer.

Synthetic lethal interaction of combined CD26 and Bcl-xL inhibition is a powerful anticancer therapy against hepatocellular carcinoma

AIM

CD26 is a membrane glycoprotein that has multiple functions, including dipeptidyl peptidase IV activity. CD26 expression varies in different tumor types, and its role in tumor growth in hepatocellular carcinoma (HCC) remains unclear.

METHODS

CD26 expression levels were examined in resected HCC and surrounding non-cancerous lesions. The effect of CD26 knockdown on the cellular proliferation of HepG2 or Huh7 cells, both of which highly express CD26, was studied in vitro.

RESULTS

CD26 mRNA expression levels were significantly increased in HCC compared with their surrounding non-cancerous lesions. We confirmed that various HCC cell lines, especially HepG2 and Huh7 cells, showed high expression levels of CD26. siRNA-mediated knockdown of CD26 suppressed hepatoma cell growth in vitro. CD26 knockdown induced cell cycle arrest through the upregulation of Cip/Kip family proteins, p21 in HepG2 cells and p27 in Huh7 cells. CD26 knockdown did not affect apoptosis, but it increased expressions of the pro-apoptotic proteins Bim and Bak and the anti-apoptotic protein Bcl-xL, suggesting an addiction of CD26 knockdown cells to Bcl-xL for survival. We thus treated CD26 knockdown cells with ABT-737, a Bcl-xL/-2/-w inhibitor, and observed that the synthetic lethal interaction of combined Bcl-xL and CD26 inhibition induced significant apoptosis and impaired cellular viability.

CONCLUSION

CD26 mRNA was overexpressed in HCC, and its inhibition suppressed cellular proliferation through cell cycle arrest. The combined use of CD26 knockdown with a Bcl-xL inhibitor further elicited substantial apoptosis and therefore may serve as a powerful anticancer combination therapy against HCC.

Dipeptidyl peptidase 4 promotes epithelial cell transformation and breast tumourigenesis via induction of PIN1 gene expression

BACKGROUND AND PURPOSE

Dipeptidyl peptidase 4 (DPP4) is an aminopeptidase that is widely expressed in different cell types. Recent studies suggested that DPP4 plays an important role in tumour progression in several human malignancies. Here we have examined the mechanisms by which up-regulation of DPP4 expression causes epithelial transformation and mammary tumourigenesis.

EXPERIMENTAL APPROACH

Expression of DPP4 and the peptidylprolyl cis/trans isomerase, NIMA-interacting 1 (PIN1), and the cytotoxic effects of combined treatment with sitagliptin and juglone were investigated by immunohistochemistry, immunoblotting, real-time PCR, TUNEL and soft agar assays, using MCF7 cells. The effects of sitagliptin on tumour development in vivo were studied in the syngeneic 4T1 metastatic breast cancer model.

KEY RESULTS

Activity of the transcription factor E2F1 induced by EGF was enhanced by DPP4, thus increasing PIN1 expression. Furthermore, DPP4 enhanced MEK/ERK and JNK/c-Jun signalling induced by EGF, inducing AP-1 activity and epithelial cell transformation. In contrast, DPP4 silencing or DPP4 inhibition in MCF7 cells inhibited PIN1 expression via E2F1 activity induced by EGF, decreasing colony formation and inducing DNA fragmentation. In the syngeneic 4T1 metastatic breast cancer model, DPP4 overexpression increased tumour development, whereas treatment with sitagliptin and/or juglone suppressed it. Consistent with these observations, DPP4 levels were positively correlated with PIN1 expression in human breast cancer.

CONCLUSIONS AND IMPLICATIONS

DPP4 promoted EGF-induced epithelial cell transformation and mammary tumourigenesis via induction of PIN1 expression, suggesting that sitagliptin targeting of DPP4 could be a treatment strategy in patients with breast cancer.

Dipeptidylpeptidase 4 inhibition enhances lymphocyte trafficking, improving both naturally occurring tumor immunity and immunotherapy

The success of antitumor immune responses depends on the infiltration of solid tumors by effector T cells, a process guided by chemokines. Here we show that in vivo post-translational processing of chemokines by dipeptidylpeptidase 4 (DPP4, also known as CD26) limits lymphocyte migration to sites of inflammation and tumors. Inhibition of DPP4 enzymatic activity enhanced tumor rejection by preserving biologically active CXCL10 and increasing trafficking into the tumor by lymphocytes expressing the counter-receptor CXCR3. Furthermore, DPP4 inhibition improved adjuvant-based immunotherapy, adoptive T cell transfer and checkpoint blockade. These findings provide direct in vivo evidence for control of lymphocyte trafficking via CXCL10 cleavage and support the use of DPP4 inhibitors for stabilizing biologically active forms of chemokines as a strategy to enhance tumor immunotherapy.

Rat-derived amniotic epithelial cells differentiate into mature hepatocytes in vivo with no evidence of cell fusion

Amniotic epithelial cells (AEC) derived from human placenta represent a useful and noncontroversial source for liver-based regenerative medicine. Previous studies suggested that human- and rat-derived AEC differentiate into hepatocyte-like cells upon transplantation. In the retrorsine (RS) model of liver repopulation, clusters of donor-derived cells engrafted in the recipient liver and, importantly, showed characteristics of mature hepatocytes. The aim of the current study was to investigate the possible involvement of cell fusion in the emergence of hepatocyte clusters displaying a donor-specific phenotype. To this end, 4-week-old GFP(+)/DPP-IV(-) rats were treated with RS and then transplanted with undifferentiated AEC isolated from the placenta of DPP-IV(+) pregnant rats at 16-19 days of gestational age. Results indicated that clusters of donor-derived cells were dipeptidyl peptidase type IV (DPP-IV) positive, but did not express the green fluorescent protein (GFP), suggesting that rat amniotic epithelial cells (rAEC) did not fuse within the host parenchyma, as no colocalization of the two tags was observed. Moreover, rAEC-derived clusters expressed markers of mature hepatocytes (eg, albumin, cytochrome P450), but were negative for the expression of biliary/progenitor markers (eg, epithelial cell adhesion molecule [EpCAM]) and did not express the marker of preneoplastic hepatic nodules glutathione S-transferase P (GST-P). These results extend our previous findings on the potential of AEC to differentiate into mature hepatocytes and suggest that this process can occur in the absence of cell fusion with host-derived cells. These studies support the hypothesis that amnion-derived epithelial cells can be an effective cell source for the correction of liver disease.

Dysregulated serum response factor triggers formation of hepatocellular carcinoma

The ubiquitously expressed transcriptional regulator serum response factor (SRF) is controlled by both Ras/MAPK (mitogen-activated protein kinase) and Rho/actin signaling pathways, which are frequently activated in hepatocellular carcinoma (HCC). We generated SRF-VP16iHep mice, which conditionally express constitutively active SRF-VP16 in hepatocytes, thereby controlling subsets of both Ras/MAPK- and Rho/actin-stimulated target genes. All SRF-VP16iHep mice develop hyperproliferative liver nodules that progresses to lethal HCC. Some murine (m)HCCs acquire Ctnnb1 mutations equivalent to those in human (h)HCC. The resulting transcript signatures mirror those of a distinct subgroup of hHCCs, with shared activation of oncofetal genes including Igf2, correlating with CpG hypomethylation at the imprinted Igf2/H19 locus.

CONCLUSION

SRF-VP16iHep mHCC reveal convergent Ras/MAPK and Rho/actin signaling as a highly oncogenic driver mechanism for hepatocarcinogenesis. This suggests simultaneous inhibition of Ras/MAPK and Rho/actin signaling as a treatment strategy in hHCC therapy.

Dipeptidyl peptidase-4 inhibitor attenuates hepatic fibrosis via suppression of activated hepatic stellate cell in rats

BACKGROUND

Dipeptidyl peptidase-4 inhibitor (DPP4-I) is clinically used as a new oral antidiabetic agent. Although DPP4 is reportedly associated with the progression of chronic liver diseases, the effect of DPP4-I on liver fibrosis development is still obscure. This study was designed to elucidate the effect of DPP4-I on liver fibrosis development in conjunction with the activated hepatic stellate cells (Ac-HSCs).

METHODS

The antifibrotic effect of DPP4-I was assessed in vivo and in vitro using porcine serum-induced experimental liver fibrosis model. DPP4-I, sitagliptin, at a clinically comparable low dose was administered by gavage daily.

RESULTS

DPP4-I significantly attenuated liver fibrosis development along with the suppression of hepatic transforming growth factor (TGF)-β1, total collagen, and tissue inhibitor of metalloproteinases-1 in a dose-dependent manner. These suppressive effects occurred almost concurrently with the attenuation of HSCs activation. Our in vitro studies showed that DPP4-I inhibited platelet-derived growth factor-BB-mediated proliferation of the Ac-HSCs as well as upregulation of TGF-β1 and α1(I)-procollagen at magnitudes similar to those of the in vivo studies. The inhibitory effects of DPP4-I against HSCs proliferation and fibrogenic gene expression are mediated through the inhibition of the phosphorylation of ERK1/2, p38 and Smad2/3, respectively.

CONCLUSIONS

DPP4-I markedly inhibits liver fibrosis development in rats via suppression of HSCs proliferation and collagen synthesis. These suppressive effects are associated with dephosphorylation of ERK1/2, p38 and Smad2/3 in the HSCs. Since DPP4-I is widely used in clinical practice, this drug may represent a potential new therapeutic strategy against liver fibrosis in the near future.

Dipeptidyl peptidase-4 inhibitors: multitarget drugs, not only antidiabetes drugs

Dipeptidyl peptidase (DPP)-4 inhibitors are a new class of antidiabetic agents that reduce blood glucose by preventing the degradation of the endogenous incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide. Protection by DPP-4 inhibitors of β-cell function has been demonstrated in patients with type 2 diabetes. Because DPP-4 is an enzyme widely expressed in humans, DPP-4 inhibitors are speculated to be multitarget agents. However, other potential therapeutic benefits of DPP-4 inhibitors remain unknown. Recently, some therapeutic effects of DPP-4 inhibitors, such as immune regulation, cardiovascular protection, and anti-inflammatory effects, have been observed. This article provides a systematic and comprehensive review of current research into the newly found effects and mechanism of action of DPP-4 inhibitors in a therapeutic context.

Regulation of dipeptidyl peptidase 8 and 9 expression in activated lymphocytes and injured liver

AIM

To investigate the expression of dipeptidyl peptidase (DPP) 8 and DPP9 in lymphocytes and various models of liver fibrosis.

METHODS

DPP8 and DPP9 expression were measured in mouse splenic CD4⁺ T-cells, CD8⁺ T-cells and B-cells (B220⁺), human lymphoma cell lines and mouse splenocytes stimulated with pokeweed mitogen (PWM) or lipopolysaccharide (LPS), and in dithiothreitol (DTT) and mitomycin-C treated Raji cells. DPP8 and DPP9 expression were measured in epidermal growth factor (EGF) treated Huh7 hepatoma cells, in fibrotic liver samples from mice treated with carbon tetrachloride (CCl₄) and from multidrug resistance gene 2 (Mdr2/Abcb4) gene knockout (gko) mice with biliary fibrosis, and in human end stage primary biliary cirrhosis (PBC).

RESULTS

All three lymphocyte subsets expressed DPP8 and DPP9 mRNA. DPP8 and DPP9 expression were upregulated in both PWM and LPS stimulated mouse splenocytes and in both Jurkat T- and Raji B-cell lines. DPP8 and DPP9 were downregulated in DTT treated and upregulated in mitomycin-C treated Raji cells. DPP9-transfected Raji cells exhibited more annexin V⁺ cells and associated apoptosis. DPP8 and DPP9 mRNA were upregulated in CCl₄ induced fibrotic livers but not in the lymphocytes isolated from such livers, while DPP9 was upregulated in EGF stimulated Huh7 cells. In contrast, intrahepatic DPP8 and DPP9 mRNA expression levels were low in the Mdr2 gko mouse and in human PBC compared to non-diseased livers.

CONCLUSION

These expression patterns point to biological roles for DPP8 and DPP9 in lymphocyte activation and apoptosis and in hepatocytes during liver disease pathogenesis.

Dipeptidyl peptidase-4: A key player in chronic liver disease

Dipeptidyl peptidase-4 (DPP-4) is a membrane-associated peptidase, also known as CD26. DPP-4 has widespread organ distribution throughout the body and exerts pleiotropic effects via its peptidase activity. A representative target peptide is glucagon-like peptide-1, and inactivation of glucagon-like peptide-1 results in the development of glucose intolerance/diabetes mellitus and hepatic steatosis. In addition to its peptidase activity, DPP-4 is known to be associated with immune stimulation, binding to and degradation of extracellular matrix, resistance to anti-cancer agents, and lipid accumulation. The liver expresses DPP-4 to a high degree, and recent accumulating data suggest that DPP-4 is involved in the development of various chronic liver diseases such as hepatitis C virus infection, non-alcoholic fatty liver disease, and hepatocellular carcinoma. Furthermore, DPP-4 occurs in hepatic stem cells and plays a crucial role in hepatic regeneration. In this review, we described the tissue distribution and various biological effects of DPP-4. Then, we discussed the impact of DPP-4 in chronic liver disease and the possible therapeutic effects of a DPP-4 inhibitor.

Dipeptidylpeptidase--IV, a key enzyme for the degradation of incretins and neuropeptides: activity and expression in the liver of lean and obese rats

Given the scarcity of donors, moderately fatty livers (FLs) are currently being considered as possible grafts for orthotopic liver transplantation (OLT), notwithstanding their poor tolerance to conventional cold preservation. The behaviour of parenchymal and sinusoidal liver cells during transplantation is being studied worldwide. Much less attention has been paid to the biliary tree, although this is considered the Achille's heel even of normal liver transplantation. To evaluate the response of the biliary compartment of FLs to the various phases of OLT reliable markers are necessary. Previously we demonstrated that Alkaline Phosphatase was scarcely active in bile canaliculi of FLs and thus ruled it out as a marker. As an alternative, dipeptidylpeptidase-IV (DPP-IV), was investigated. This ecto-peptidase plays an important role in glucose metabolism, rapidly inactivating insulin secreting hormones (incretins) that are important regulators of glucose metabolism. DPP-IV inhibitors are indeed used to treat Type II diabetes. Neuropeptides regulating bile transport and composition are further important substrates of DPP-IV in the enterohepatic axis. DPP-IV activity was investigated with an azo-coupling method in the liver of fatty Zucker rats (fa/fa), using as controls lean Zucker (fa/+) and normal Wistar rats. Protein expression was studied by immunofluorescence with the monoclonal antibody (clone 5E8). In Wistar rat liver, DPP-IV activity and expression were high in the whole biliary tree, and moderate in sinusoid endothelial cells, in agreement with the literature. Main substrates of DPP-IV in hepatocytes and cholangiocytes could be incretins GLP-1 and GIP, and neuropeptides such as vasoactive intestinal peptide (VIP) and substance P, suggesting that these substances are inactivated or modified through the biliary route. In lean Zucker rat liver the enzyme reaction and protein expression patterns were similar to those of Wistar rat. In obese rat liver the patterns of DPP-IV activity and expression in hepatocytes reflected the morphological alterations induced by steatosis as lipid-rich hepatocytes had scarce activity, located either in deformed bile canaliculi or in the sinusoidal and lateral domains of the plasma membrane. These findings suggest that bile canaliculi in steatotic cells have an impaired capacity to inactivate incretins and neuropeptides. Incretin and/or neuropeptide deregulation is indeed thought to play important roles in obesity and insulin-resistance. No alteration in enzyme activity and expression was found in the upper segments of the biliary tree of obese respect to lean Zucker and Wistar rats. In conclusion, this research demonstrates that DPP-IV is a promising in situ marker of biliary functionality not only of normal but also of fatty rats. The approach, initially devised to investigate the behaviour of the liver during the various phases of transplantation, appears to have a much higher potentiality as it could be further exploited to investigate any pathological or stressful conditions involving the biliary tract (i.e., metabolic syndrome and cholestasis) and the response of the biliary tract to therapy and/or to surgery.

The growth pattern of transplanted normal and nodular hepatocytes

Overt neoplasia is often the end result of a long biological process beginning with the appearance of focal lesions of altered tissue morphology. While the putative clonal nature of focal lesions has often been emphasized, increasing attention is being devoted to the possible role of an altered growth pattern in the evolution of carcinogenesis. Here we compare the growth patterns of normal and nodular hepatocytes in a transplantation system that allows their selective clonal proliferation in vivo. Rats were pre-treated with retrorsine, which blocks the growth of resident hepatocytes, and were then transplanted with hepatocytes isolated from either normal liver or hepatocyte nodules. Both cell types were able to proliferate extensively in the recipient liver, as expected. However, their growth pattern was remarkably different. Clusters of normal hepatocytes integrated in the host liver, displaying a normal histology; however, transplanted nodular hepatocytes formed new hepatocyte nodules, with altered morphology and sharp demarcation from surrounding host liver. Both the expression and distribution of proteins involved in cell polarity, cell communication, and cell adhesion, including connexin 32, E-cadherin, and matrix metalloproteinase-2, were altered in clusters of nodular hepatocytes. Furthermore, we were able to show that down-regulation of connexin 32 and E-cadherin in nodular hepatocyte clusters was independent of growth rate. These results support the concept that a dominant pathway towards neoplastic disease in several organs involves defect(s) in tissue pattern formation.

CD26 expression in mature B-cell neoplasia: its possible role as a new prognostic marker in B-CLL

CD26 (dipeptidyl peptidase IV, DPP IV) is widely expressed by T and natural killer (NK) cells, epithelial and endothelial cells of different tissues, and it is strongly upregulated in activated B-cells; moreover it plays a regulatory role in the neoplastic transformation and progression of various types of tumours. CD26 expression was evaluated by means of flow cytometry in various peripheral B-cell lymphoid tumours: 12 follicular and 12 mantle cell lymphomas, 20 multiple myelomas (MMs), 12 hairy cell leukaemias (HCLs), 112 chronic lymphocytic leukaemias (CLLs), 20 CD5(negative) B-cell chronic lymphoproliferative diseases (CD5(neg) B-CLPDs) and 12 diffuse large cell lymphomas (DLCLs). CD26 expression was absent or barely detectable in follicular and mantle cell lymphomas, high in MMs and HCLs, and variable in CLLs, in CD5(neg) B-CLPDs and in DLCLs. CD26 significantly correlated with CD49d and CD38 expressions (p < 0.0001) in B-CLLs, and there was a significant correlation between CD26 and ZAP-70 expressions or IgVH mutational status (p < 0.0001). After a median follow-up of 36 months, 65 B-CLL patients were treated; taking 10% as the best CD26 cut-off value, Kaplan-Meier curves revealed a significantly shorter time to treatment in the CD26-positive cases (p < 0.0001). Overall, our data indicate that CD26 expression may identify subsets of B-CLL patients with an unfavourable clinical outcome in terms of therapeutic need, thus suggesting its potential role as a marker (together with CD38 and CD49d) in a future routine cytofluorimetric panel to be validated for the prognostic stratification of B-CLLs.

Serum level of CD26 predicts time to first treatment in early B-chronic lymphocytic leukemia

We analyzed the correlation between well-established biological parameters of prognostic relevance in B-cell chronic lymphocytic leukemia (CLL) [i.e. mutational status of the immunoglobulin heavy chain variable region (IgV(H)), ZAP-70- and CD38-expression] and serum levels of CD26 (dipeptidyl peptidase IV, DPP IV) by evaluating the impact of these variables on the time to first treatment (TFT) in a series of 69 previously untreated Binet stage A B-cell CLL patients. By using a commercial ELISA we found that with exception of a borderline significance for ZAP-70 (P = 0.07) and CD38 (P = 0.08), circulating levels of CD26 did not correlate with either Rai substages (P = 0.520) or other biomarker [beta2-microglobulin (P = 0.933), LDH (P = 0.101), mutational status of IgV(H) (P = 0.320)]. Maximally selected log-rank statistic plots identified a CD26 serum concentration of 371 ng/mL as the best cut-off. This threshold allowed the identification of two subsets of patients with CD26 serum levels higher and lower that 371 ng/mL respectively, whose clinical outcome was different with respect to TFT (i.e. 46% and 71% at 5 yr respectively; P = 0.005). Along with higher serum levels of CD26, the univariate Cox proportional hazard model identified absence of mutation in IgV(H) (P < 0.0001) as predictor of shorter TFT. As in multivariate analysis all these parameters maintained their discriminating power (mutational status of IgV(H,)P < 0.0001; soluble CD26, P = 0.02) their combined effect on clinical outcome was assessed. When three groups were considered: (1) Low-risk group (n = 31), patients with concordant IgVH(mut) and low level of soluble CD26; (2) intermediate risk group (n = 26), patients with discordant pattern; (3) high-risk group (n = 12), patients with concordant IgVH(unmut) and high level of soluble CD26, differences in the TFT were statistically significant, with a TFT at 5 yr of respectively 88%, 51% and 43% (P < 0.0001). Our results indicate that in early B-cell CLL biological profile including among other parameters soluble CD26 may provide a useful insight into the complex interrelationship of prognostic variables. Furthermore, CD26 along with mutational status of IgV(H) can be adequately used to predict clinical behavior of patients with low risk disease.

The protease complex consisting of dipeptidyl peptidase IV and seprase plays a role in the migration and invasion of human endothelial cells in collagenous matrices

Dipeptidyl peptidase IV (DPP4/CD26) and seprase/fibroblast activation protein alpha are homologous type II transmembrane, homodimeric glycoproteins that exhibit unique prolyl peptidase activities. Human DPP4 is ubiquitously expressed in epithelial and endothelial cells and serves multiple functions in cleaving the penultimate positioned prolyl bonds at the NH(2) terminus of a variety of physiologically important peptides in the circulation. Recent studies showed a linkage between DPP4 and down-regulation of certain chemokines and mitogenic growth factors, and degradation of denatured collagens (gelatin), suggesting a role of DPP4 in the cell invasive phenotype. Here, we found the existence of a novel protease complex consisting of DPP4 and seprase in human endothelial cells that were activated to migrate and invade in the extracellular matrix in vitro. DPP4 and seprase were coexpressed with the three major protease systems (matrix metalloproteinase, plasminogen activator, and type II transmembrane serine protease) at the cell surface and organize as a complex at invadopodia-like protrusions. Both proteases were colocalized at the endothelial cells of capillaries, but not large blood vessels, in invasive breast ductal carcinoma in vivo. Importantly, monoclonal antibodies against the gelatin-binding domain of DPP4 blocked the local gelatin degradation by endothelial cells in the presence of the major metallo- and serine protease systems that modified pericellular collagenous matrices and subsequent cell migration and invasion. Thus, we have identified a novel mechanism involving the DPP4 gelatin-binding domain of the DPP4-seprase complex that facilitates the local degradation of the extracellular matrix and the invasion of the endothelial cells into collagenous matrices.

Breast cancer resistance protein (BCRP/ABCG2) is expressed by progenitor cells/reactive ductules and hepatocytes and its expression pattern is influenced by disease etiology and species type: possible functional consequences

Breast cancer resistance protein (BCRP/ABCG2) is an ATP-binding cassette transport protein that is expressed in several organs including the liver. Previous studies have shown that ABC transport proteins play an important pathophysiological role in several liver diseases. However, to date, expression pattern and possible role of BCRP in human liver diseases and animal models have not been studied in detail. Here we investigated the expression pattern of BCRP in normal liver, chronic parenchymal and biliary human liver diseases, and parallel in different rat models of liver diseases. Expression was studied by immunohistochemistry and additionally by RT-PCR analysis in Thy-1-positive rat oval cells. Bile ducts, hepatic progenitor cells, reactive bile ductules, and blood vessel endothelium were immunoreactive for BCRP in normal liver and all types of human liver diseases and in rat models. BCRP was expressed by the canalicular membrane of hepatocytes in normal and diseased human liver, but never in rat liver. Remarkably, there was also expression of BCRP at the basolateral pole of human hepatocytes, and this was most pronounced in chronic biliary diseases. In conclusion, BCRP positivity in the progenitor cells/reactive ductules could contribute to the resistance of these cells to cytotoxic agents and xenotoxins. Basolateral hepatocytic expression in chronic biliary diseases may be an adaptive mechanism to pump bile constituents back into the sinusoidal blood. Strong differences between human and rat liver must be taken into account in future studies with animal models.

Adenosine downregulates DPPIV on HT-29 colon cancer cells by stimulating protein tyrosine phosphatase(s) and reducing ERK1/2 activity via a novel pathway

The multifunctional cell-surface protein dipeptidyl peptidase IV (DPPIV/CD26) is aberrantly expressed in many cancers and plays a key role in tumorigenesis and metastasis. Its diverse cellular roles include modulation of chemokine activity by cleaving dipeptides from the chemokine NH(2)-terminus, perturbation of extracellular nucleoside metabolism by binding the ecto-enzyme adenosine deaminase, and interaction with the extracellular matrix by binding proteins such as collagen and fibronectin. We have recently shown that DPPIV can be downregulated from the cell surface of HT-29 colorectal carcinoma cells by adenosine, which is a metabolite that becomes concentrated in the extracellular fluid of hypoxic solid tumors. Most of the known responses to adenosine are mediated through four different subtypes of G protein-coupled adenosine receptors: A(1), A(2A), A(2B), and A(3). We report here that adenosine downregulation of DPPIV from the surface of HT-29 cells occurs independently of these classic receptor subtypes, and is mediated by a novel cell-surface mechanism that induces an increase in protein tyrosine phosphatase activity. The increase in protein tyrosine phosphatase activity leads to a decrease in the tyrosine phosphorylation of ERK1/2 MAP kinase that in turn links to the decline in DPPIV mRNA and protein. The downregulation of DPPIV occurs independently of changes in the activities of protein kinases A or C, phosphatidylinositol 3-kinase, other serine/threonine phosphatases, or the p38 or JNK MAP kinases. This novel action of adenosine has implications for our ability to manipulate adenosine-dependent events within the solid tumor microenvironment.

Adenosine down-regulates the surface expression of dipeptidyl peptidase IV on HT-29 human colorectal carcinoma cells: implications for cancer cell behavior

Dipeptidyl peptidase IV (DPPIV) is a multifunctional cell-surface protein that, as well as having dipeptidase activity, is the major binding protein for adenosine deaminase (ADA) and also binds extracellular matrix proteins such as fibronectin and collagen. It typically reduces the activity of chemokines and other peptide mediators as a result of its enzymatic activity. DPPIV is aberrantly expressed in many cancers, and decreased expression has been linked to increases in invasion and metastasis. We asked whether adenosine, a purine nucleoside that is present at increased levels in the hypoxic tumor microenvironment, might affect the expression of DPPIV at the cell surface. Treatment with a single dose of adenosine produced an initial transient (1 to 4 hours) modest (approximately 10%) increase in DPPIV, followed by a more profound (approximately 40%) depression of DPPIV protein expression at the surface of HT-29 human colon carcinoma cells, with a maximal decline being reached after 48 hours, and persisting for at least a week with daily exposure to adenosine. This down-regulation ofDPPIV occurred at adenosine concentrations comparable to those present within the extracellular fluid of colorectal tumors growing in vivo, and was not elicited by inosine or guanosine. Neither cellular uptake of adenosine nor its phosphorylation was necessary for the down-regulation of DPPIV. The decrease in DPPIV protein at the cell surface was paralleled by decreases in DPPIV enzyme activity, binding of ADA, and the ability of the cells to bind to and migrate on cellular fibronectin. Adenosine, at concentrations that exist within solid tumors, therefore acts at the surface of colorectal carcinoma cells to decrease levels and activities of DPPIV. This down-regulation of DPPIV may increase the sensitivity of cancer cells to the tumor-promoting effects of adenosine and their response to chemokines and the extracellular matrix, facilitating their expansion and metastasis.

CD26/dipeptidyl peptidase IV enhances expression of topoisomerase II alpha and sensitivity to apoptosis induced by topoisomerase II inhibitors

CD26/dipeptidyl peptidase IV (DPPIV) is a cell surface-bound ectopeptidase with important roles in T-cell activation and tumour biology. We now report that CD26/DPPIV enhances sensitivity to apoptosis induced by the antineoplastic agents doxorubicin and etoposide. In particular, CD26/DPPIV presence is associated with increased susceptibility to the mitochondrial pathway of apoptosis, documented by enhanced cleavage of poly (ADP ribose) polymerase (PARP), caspase-3 and caspase-9, Bcl-xl, and Apaf-1, as well as increased expression of death receptor 5 (DR5). We also show that the caspase-9-specific inhibitor z-LEHD-fmk inhibits drug-mediated apoptosis, leading to decreased PARP and caspase-3 cleavage, and reduced DR5 expression. Importantly, through detailed studies that demonstrate the association between topoisomerase II alpha expression and DPPIV activity, our data provide further evidence of the key role played by CD26 in biological processes.

T-large granular lymphocyte lymphoproliferative disorder: expression of CD26 as a marker of clinically aggressive disease and characterization of marrow inhibition

T-large granular lymphocyte lymphoproliferative disorder (T-LGL LPD) is an indolent disease characterized by prolonged cytopenia and the presence of circulating large granular lymphocytes in the patient's peripheral blood. Although the disease is commonly thought of as indolent, most patients eventually require therapy because of recurrent infections secondary to neutropenia as well as a need for frequent blood product transfusions. CD26 is a 110-kDa surface glycoprotein with an essential role in T-cell function, including being a marker of T-cell activation and a mediator of T-cell activating signals. In this study, we evaluated CD26 expression in T-LGL patients and correlate CD26 expression with clinical behaviour. In addition, we examined the potential mechanism of cytopenia that is associated with this disorder. Our findings suggest that CD26 is a marker of aggressive T-LGL LPD and that CD26-related signalling may be aberrant in T-LGL LPD. Furthermore, inhibition of granulocyte-macrophage colony-forming units may be mediated by CD8+ cells of T-LGL LPD patients and is major histocompatibility complex class I-restricted.

Similar increased serum dipeptidyl peptidase IV activity in chronic hepatitis C and other viral infections

BACKGROUND

Dipeptidyl peptidase IV is a transmembrane enzyme widely expressed in many cell types, but also present as a soluble form in biological fluids. Its abnormal activity is sometimes associated with liver disease related pathologies.

OBJECTIVES

The aim of this study was to evaluate the clinical relevance of changes in serum DPPIV activity in hepatitis C and other viral infections.

STUDY DESIGN

DPPIV activity was assessed by using a microplate-based colorimetric assay on serum from 88 subjects: 12 healthy uninfected controls, 10 patients with primary biliary cirrhosis (PBC) as a reference group, 36 HCV-infected patients, and patients suffering from viral infections of different etiologies. Levels of DPPIV activity were compared with: (1) those of other serum biochemical parameters such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyl transpeptidase (GGT), and bilirubin concentrations; and (2) criteria representative of liver histological status.

RESULTS

Compared with healthy subjects, DPPIV activity was significantly increased during viral infections and in PBC (P<0.01). In HCV-infected patients, the median activity (interquartile range, IQR), 29.78 IU/l (24.66-35.95), differed significantly (P<0.05) from that of controls: 21.42 (19.76-24.93). No correlation was observed between DPPIV activity and either ALT, AST, bilirubin, or the stage of liver fibrosis and necroinflammatory activity, although GGT was moderately correlated (r=0.58, P<0.05).

CONCLUSIONS

Although we confirmed an elevation of serum DPPIV activity in PBC, it seems to be a non-specific phenomenon common to viral infections. The absence of correlation between serum DPPIV and markers of liver disease in HCV-infected patients, suggests that this activity originates not only from the liver, but also from other sources such as peripheral blood cells involved in the control of viral infections.