Associations of non-invasive indices of liver steatosis and fibrosis with progressive kidney impairment in adults with type 2 diabetes.

AIMS: Longitudinal data linking non-alcoholic fatty liver disease to kidney dysfunction in type 2 diabetes (T2D) are limited. This study evaluated the associations of non-invasive indices of liver steatosis and liver fibrosis with kidney impairment, and the mediatory role of the pro-angiogenic factor leucine-rich α-2 glycoprotein 1 (LRG1). METHODS: T2D adults (n = 2057) were followed for a mean period of 6.1 ± 1.6 years. Baseline liver steatosis [(hepatic steatosis index (HSI) and Zhejiang University index (ZJU)] and liver fibrosis [aspartate transaminase/alanine transaminase ratio (AAR) and BARD] indices derived from composite scoring systems were calculated. Plasma LRG1 levels were quantified using immunoassay. The study outcomes were progressive kidney function decline defined as estimated glomerular filtration rate (eGFR) decline of ≥ 40% and albuminuria progression defined as an increase in albuminuria category. RESULTS: Cross-sectionally, liver steatosis and liver fibrosis indices were associated with increased albuminuria (urinary albumin/creatinine ratio ≥ 30 µg/mg) and reduced renal function (eGFR < 60 mL/min/1.73 m2) after covariate adjustment, respectively. Approximately 32% of the participants experienced progressive kidney function decline, while 38% had albuminuria worsening over time. Longitudinal analysis revealed that baseline AAR (hazard ratio: 1.56; 95% CI 1.15-2.11) and BARD (hazard ratio: 1.16, 95% CI 1.04-1.28) predicted progressive kidney function decline, partly mediated by LRG1. In contrast, liver steatosis (HSI and ZJU) but not liver fibrosis (AAR and BARD) indices were independently associated with albuminuria progression. CONCLUSIONS: Increased liver steatosis scores were associated with albuminuria deterioration. Conversely, liver fibrosis indices may be associated with progressive kidney function decline, potentially driven by increased inflammation and angiogenesis.

Association of Baseline Triglyceride-Glucose Index with Poor Glycemic Control and Diabetes Remission After Metabolic Surgery.

PURPOSE: The utility of insulin resistance (IR) as a predictor of diabetes remission after metabolic surgery is not well-defined. We assessed the association of baseline surrogate IR indices including triglyceride-glucose (TyG) index and homeostatic model assessment for IR (HOMA-IR) with glycemic control and diabetes remission after metabolic surgery. MATERIALS AND METHODS: Patients with type 2 diabetes scheduled for metabolic surgery were recruited at a single-center (n = 149; age: 44 ± 10 years, 47.7% men, body mass index: 41.5 ± 7.5 kg/m2), and followed-up for 12 months postoperatively. The relationships between the IR indices and poor glycemic control (HbA1c ≥ 7%) at baseline or complete diabetes remission (HbA1c < 6% without glucose-lowering medications at 12 months) post-surgery were examined. RESULTS: Elevated TyG index was associated with poor glycemic control cross-sectionally. Compared with non-remitters, lower baseline TyG index levels were observed in individuals with complete diabetes remission after surgery (P = 0.012); whereas HOMA-IR was not significantly different. Consistently, the proportion of diabetes non-remitters (compared to remitters) increased with increasing TyG tertiles from 1 to 3 (P = 0.015). Both TyG index (relative risk = 0.62, 95% CI = 0.42-0.91, P = 0.014) and TyG tertile 1 (relative risk = 1.99, 95% CI = 1.25-3.24, P = 0.003) independently predicted diabetes remission. The TyG index identified diabetes remission with an area under the curve of 0.68. The optimal TyG threshold was 9.41, yielding a sensitivity of 69.6%, specificity of 60.9%, positive predictive value of 64.0%, and negative predictive value of 66.7%. CONCLUSION: TyG index, previously suggested to predominantly reflect muscle IR, outperforms HOMA-IR as an IR indicator associated with glycemic control and diabetes remission after metabolic surgery.

Long-Term Observation of a Man With Severe Obesity and Undiagnosed Monogenic Diabetes Serendipitously Treated With Metabolic Surgery.

A 43-year-old man, with severe obesity (43 kg/m2) and diabetes (presumed as type 2 diabetes [T2D]), underwent vertical sleeve gastrectomy in 2009 and Roux-en-Y gastric bypass in 2013. Recently, whole exome sequencing (conducted to search for monogenic obesity) serendipitously revealed that the individual harbored a heterozygous glucokinase (GCK) variant p.(Arg422Leu) that was bioinformatically strongly predicted to be likely pathogenic. Therefore, he is likely to have concomitant maturity-onset diabetes of the young (MODY) type 2 (GCK-MODY). A retrospective evaluation of the clinical data showed that the subject was diagnosed with T2D (given his severe obesity) in 2005 and was treated with oral antidiabetic monotherapy. His hyperglycemia was mostly mild (HbA1c [hemoglobin] < 8.1%), consistent with that of MODY2, despite severe obesity. After vertical sleeve gastrectomy, complete diabetes remission (HbA1c <6.0% and fasting plasma glucose <5.6 mmol/L without use of antidiabetic medication) was achieved. The percentage of maximum body weight loss attained after surgery was 23.6%. Euglycemia was maintained during the subsequent decade, up to the last follow-up in 2019, without any sign of hypoglycemia. In conclusion, we report a decade-long clinical experience of a man with severe obesity and diabetes likely due to the coexistence of GCK-MODY and T2D, serendipitously treated with metabolic surgery. Interestingly, metabolic surgery was effective and safe for him.

Metabolic Surgery Diabetes Remission (MDR) Score: a New Preoperative Scoring System for Predicting Type 2 Diabetes Remission at 1 Year After Metabolic Surgery in the Singapore Multi-ethnic Asian Setting.

PURPOSE: The utility of available scoring systems for type 2 diabetes (T2D) remission prediction after metabolic surgery has not been defined in a multi-ethnic Asian population like Singapore. We sought to assess the predictive performance of the Asia-developed ABCD scoring system for T2D remission after metabolic surgery, and develop a new algorithm to improve prediction. MATERIALS AND METHODS: We conducted a retrospective analysis of adults with T2D who underwent either Roux-en-Y gastric bypass or sleeve gastrectomy between 2007 and 2018, and followed for 1 year postoperatively (n = 114, mean age 46 ± 9 years, 48.2% men, body mass index 40.1 ± 6.6 kg/m2). The primary outcome was complete T2D remission defined as HbA1c < 6% without the use of anti-diabetic medication at 1 year after surgery. RESULTS: Complete T2D remission was observed in 47.4% of subjects at 1 year post-surgery. Stepwise logistic regression identified preoperative age, T2D duration, HbA1c, and ß-cell function (estimated by the homeostasis model) as predictors of complete T2D remission. Based on these four variables, we constructed a new 10-point scoring system named Metabolic surgery Diabetes Remission (MDR) score. Compared with ABCD, MDR produced fewer misclassifications at the mid-high scores, achieving a predictive accuracy of 71-100% at 6 points and above. In addition, MDR achieved a higher area under the receiver operating characteristic curve than ABCD for the primary outcome (0.79 versus 0.67, P = 0.007). CONCLUSION: MDR may serve as a useful clinical scoring system for predicting short-term T2D remission after metabolic surgery in Singapore's multi-ethnic Asian cohort.

Association of the anti-angiogenic factor secreted protein and rich in cysteine (SPARC) with vascular complications among Chinese type 2 diabetic patients in Singapore.

AIMS: This study evaluated the association of the anti-angiogenic SPARC with known angiogenesis-associated factors and diabetes-related micro- and macro-vascular complications in a Singapore Chinese cohort with type 2 diabetes (T2DM). METHODS: Plasma SPARC was measured by immunoassay in 438 T2DM adults (mean age:58±11years). RESULTS: Higher SPARC levels in subjects stratified by SPARC tertiles displayed decreased pro-angiogenic adiponectin, osteopontin, vascular cell adhesion molecule (VCAM)-1 and matrix metalloproteinase (MMP)-2 concentrations (all p<0.05). The anti-angiogenic pigment epithelium-derived factor (PEDF) level was not statistically different among the SPARC tertiles. Age-adjusted partial correlation revealed significant associations of SPARC with adiponectin, osteopontin, VCAM-1, MMP-2, and PEDF (all p<0.05). Lower SPARC was accompanied by less favorable estimated glomerular filtration rate (eGFR) and carotid-femoral pulse wave velocity (PWV) readings (all p<0.05). Conversely, ankle-brachial index (ABI) reduced with increasing SPARC (p=0.048). The eGFR (B=0.834, p=0.019), PWV (B=-7.925, p=0.009), and ABI (B=-142.160, p=0.010) remained as determinants of SPARC after confounder adjustment. Moreover, individuals in the lowest SPARC tertile had increased odds of aortic stiffness (OR=1.900, 95% CI=1.103-3.274) but reduced odds of peripheral arterial disease (OR=0.400, 95% CI=0.175-0.919). However, SPARC was not independently associated with chronic kidney disease. CONCLUSIONS: The anti-angiogenic SPARC may be associated with the pathophysiology of diabetes-related macrovascular complications.

HepaCAM associates with connexin 43 and enhances its localization in cellular junctions.

HepaCAM (GlialCAM) is frequently deleted in carcinomas, and reintroduction of hepaCAM into transformed cell lines reduces cellular growth and induces senescence. Mutations in HEPACAM give rise to the neurodegenerative disease megalencephalic leukoencephalopathy with subcortical cysts (MLC) since mutated hepaCAM prevents shuttling of MLC1 protein to astrocytic junctions in the plasma membrane. Here we identify that hepaCAM associates with connexin 43, a main component of gap junctions, and enhances connexin 43 localization to the plasma membrane at cellular junctions. HepaCAM also increases the levels of connexin 43, not by enhancing its transcription but by stabilizing connexin 43 protein. In the absence of hepaCAM, connexin 43 undergoes a faster degradation via the lysosomal pathway while proteasomal degradation seems not to be involved. Mutations in hepaCAM that cause MLC, or neutralization of hepaCAM by antibodies disrupt its association with connexin 43 at cellular junctions. By discovering the requirement of hepaCAM for localizing connexin 43, a well-established tumor suppressor, to cellular junctions and stabilizing it there, this study suggests a mechanism by which deletion of hepaCAM may support tumor progression.

Regulation of myelopoiesis by CD137L signaling.

CD137 ligand (CD137L) has emerged as a powerful regulator of myelopoiesis that links emergency situations, such as infections, to the generation of additional myeloid cells, and to their activation and maturation. CD137L is expressed on the cell surface of hematopoietic stem and progenitor cells (HSPC) and antigen presenting cells (APC) as a transmembrane protein. The signaling of CD137L into HSPC induces their proliferation and differentiation to monocytes and macrophages, and in monocytes CD137L signaling induces differentiation to potent dendritic cells (DC). CD137L signaling is initiated by CD137 which is expressed by T cells, once they become activated. Some of these activated, CD137-expressing T cells migrate from the site of infection to the bone marrow where they interact with HSPC to induce myelopoiesis, or they induce monocyte to DC differentiation locally at the site of infection. Therapeutically, induction of CD137L signaling can be utilized to reinitiate myeloid differentiation in acute myeloid leukemia cells, and to generate potent DC for immunotherapy.

Tumor necrosis factor receptor 1 associates with CD137 ligand and mediates its reverse signaling.

Reverse signaling through CD137 ligand (CD137L) potently activates monocytes. However, the underlying mechanism is not well elucidated. This study provides evidence that tumor necrosis factor receptor 1 (TNFR1) acts as a coreceptor for CD137L and mediates CD137L signaling. CD137L colocalizes with TNFR1 on the plasma membrane and binds directly to TNFR1 via its extracellular domain. Using the human monocytic THP-1 cell line, we demonstrate that engagement of CD137L by recombinant CD137 protein promotes cell adhesion, apoptosis, expression of CD14, and production of IL-8 and tumor necrosis factor (TNF). Concomitantly, the expression of TNFR1 protein is down-regulated in response to CD137L activation, due to enhanced extracellular release and internalization of TNFR1. Activation of TNFR1 by TNF protein additively augments CD137L-induced IL-8 expression. Conversely, inhibition of TNFR1 activity by a TNFR1-neutralizing antibody inhibits CD137L-mediated cell adhesion, cell death, CD14 expression, and IL-8 production. Taken together, these data show that TNFR1 associates with CD137L and is required for CD137L reverse signaling.

Expression of CD137 on Hodgkin and Reed-Sternberg cells inhibits T-cell activation by eliminating CD137 ligand expression.

Hodgkin lymphoma is caused by a minority population of malignant Hodgkin and Reed-Sternberg (HRS) cells that recruit an abundance of inflammatory cells. The long-term survival of HRS cells among the vast majority of immune cells indicates that they have developed potent immune escape mechanisms. We report that the TNF receptor family member CD137 (TNFRSF9) is expressed on HRS cells, while normal B cells, from which HRS cells are most often derived, do not express CD137. In 48 of 53 cases of classical Hodgkin lymphoma, CD137 was detected on HRS cells. Ectopically expressed CD137 transferred by trogocytosis from HRS cells to neighboring HRS and antigen-presenting cells, which constitutively express the CD137 ligand (CD137L and TNFSF9), became associated with CD137L and the CD137-CD137L complex was internalized. Disappearance of CD137L from the surface of HRS and antigen-presenting cells led to reduced costimulation of T cells through CD137, reducing IFN-γ release and proliferation. Our results reveal a new regulatory mechanism for CD137L expression that mediates immune escape by HRS cells, and they identify CD137 as a candidate target for immunotherapy of Hodgkin lymphoma.

The roles of cell adhesion molecules in tumor suppression and cell migration: a new paradox.

In addition to mediating cell adhesion, many cell adhesion molecules act as tumor suppressors. These proteins are capable of restricting cell growth mainly through contact inhibition. Alterations of these cell adhesion molecules are a common event in cancer. The resulting loss of cell-cell and/or cell-extracellular matrix adhesion promotes cell growth as well as tumor dissemination. Therefore, it is conventionally accepted that cell adhesion molecules that function as tumor suppressors are also involved in limiting tumor cell migration. Paradoxically, in 2005, we identified an immunoglobulin superfamily cell adhesion molecule hepaCAM that is able to suppress cancer cell growth and yet induce migration. Almost concurrently, CEACAM1 was verified to co-function as a tumor suppressor and invasion promoter. To date, the reason and mechanism responsible for this exceptional phenomenon remain unclear. Nevertheless, the emergence of these intriguing cell adhesion molecules with conflicting roles may open a new chapter to the biological significance of cell adhesion molecules.

The immunoglobulin-like cell adhesion molecule hepaCAM induces differentiation of human glioblastoma U373-MG cells.

Subsequent to our identification of a novel immunoglobulin-like cell adhesion molecule hepaCAM, we showed that hepaCAM is frequently lost in diverse human cancers and is capable of modulating cell motility and growth when re-expressed. Very recently, a molecule identical to hepaCAM (designated as GlialCAM) was found highly expressed in glial cells of the brain. Here, we demonstrate that hepaCAM is capable of inducing differentiation of the human glioblastoma U373-MG cells. Expression of hepaCAM resulted in a significant increase in the astrocyte differentiation marker glial fibrillary acid protein (GFAP), indicating that hepaCAM promotes glioblastoma cells to undergo differentiation. To determine the relationship between hepaCAM expression level and cell differentiation, we established two U373-MG cell lines expressing hepaCAM at different levels. The results revealed that high-level hepaCAM triggered a clear increase in GFAP expression as well as morphological changes characteristic of glioblastoma cell differentiation. Furthermore, high expression of hepaCAM significantly accelerated cell adhesion but inhibited cell proliferation and migration. Concomitantly, deregulation of cell cycle regulatory proteins was detected. Expectedly, the differentiation was noticeably less apparent in cells expressing low-level hepaCAM. Taken together, our findings suggest that hepaCAM induces differentiation of the glioblastoma U373-MG cells. The degree of cell differentiation is dependent on the expression level of hepaCAM.

Interaction of the immunoglobulin-like cell adhesion molecule hepaCAM with caveolin-1.

Subsequent to our identification of the novel immunoglobulin-like cell adhesion molecule hepaCAM, we demonstrated that hepaCAM is capable of modulating cell growth and cell-extracellular matrix interactions. In this study, we examined the localization of hepaCAM in lipid rafts/caveolae as well as the interaction of hepaCAM with the caveolar structural protein caveolin-1 (Cav-1). Our results revealed that a portion of hepaCAM resided in detergent-resistant membranes and co-partitioned with Cav-1 to low buoyant density fractions characteristic of lipid rafts/caveolae. In addition, co-localization and coimmunoprecipitation assays confirmed the association of hepaCAM with Cav-1. Deletion analysis of hepaCAM showed that the extracellular first immunoglobulin domain of hepaCAM was required for binding Cav-1. Furthermore, when co-expressed, Cav-1 induced the expression of hepaCAM as well as distributed hepaCAM to intracellular Cav-1-positive caveolar structures. Taken together, our findings indicate that hepaCAM is partially localized in the lipid rafts/caveolae and interacts with Cav-1 through its first immunoglobulin domain.

Expression of hepaCAM is downregulated in cancers and induces senescence-like growth arrest via a p53/p21-dependent pathway in human breast cancer cells.

Previously, we reported the identification of a novel immunoglobulin-like cell adhesion molecule hepaCAM that is frequently downregulated and inhibits cell growth in hepatocellular carcinoma. In this study, we show that the expression of hepaCAM is suppressed in diverse human cancers. Aiming to evaluate the biological role of hepaCAM in breast cancer, we stably transfected the MCF7 cell line with either wild-type hepaCAM or its mutant hCAM-tailless that lacked the cytoplasmic domain. We found that hepaCAM inhibited colony formation and cell proliferation and arrested cells in the G(2)/M phase. Intriguingly, hepaCAM was capable of inducing cellular senescence as defined by the enlarged cell morphology and increased beta-galactosidase activity. Furthermore, hepaCAM elevated the expression levels of senescence-associated proteins including p53, p21 and p27. In contrast, cell growth inhibition and senescence were less apparent in cells overexpressing hCAM-tailless mutant. To determine if the p53-mediated pathway was involved in hepaCAM-induced senescence, we used the small-interfering RNA system to knock down endogenous p53 expression. In the presence of hepaCAM, downregulation of p53 resulted in a clear reduction of p21, insignificant change in p27 and alleviated senescence. Together, the results suggest that the expression of hepaCAM in MCF7 cells not only inhibits cell growth but also induces cellular senescence through the p53/21 pathway.

Identification of a novel gene HEPT3 that is overexpressed in human hepatocellular carcinoma and may function through its noncoding RNA.

Genetic alterations have been defined as the hallmark of cancers as they are responsible for the differences between normal and malignant phenotypes. A widely accepted approach to study genetic instability is to identify cancer-related genes, in particular, the two major groups of growth regulatory genes - oncogenes and tumour suppressor genes. Using the technique of suppression subtractive hybridisation, we identified a novel gene transcript, designated as HEPT3. RT-PCR demonstrated that HEPT3 was overexpressed in 87% (20/23) of HCC patients and in 4/5 HCC cell lines tested. Sequence analyses performed on the full-length cDNA revealed that HEPT3 is an intronless gene mapped to human chromosome 6q13-14. The gene transcript lacks an extensive open reading frame and contains an Alu sequence near the 5' terminus, indicating that HEPT3 encodes a noncoding RNA. Antisense studies on the HCC cell line HepG2 showed that, when HEPT3 expression level was reduced, cell proliferation rate was inhibited by approximately 5-fold and cell colony formation was reduced by at least 50%. Our data suggest that the novel gene HEPT3 may function through its noncoding RNA and its overexpression may play a role in hepatocarcinogenesis.

Structural and functional analyses of a novel ig-like cell adhesion molecule, hepaCAM, in the human breast carcinoma MCF7 cells.

We have recently identified a novel gene, hepaCAM, in liver that encodes a cell adhesion molecule of the immunoglobulin superfamily. In this study, we examined the characteristics of hepaCAM protein and the relationship between its structure and function, in particular its adhesive properties. The wild-type and the cytoplasmic domain-truncated mutants of hepaCAM were transfected into the human breast carcinoma MCF7 cells, and the physiological and biological properties were assessed. Biochemical analyses revealed that hepaCAM is an N-linked glycoprotein phosphorylated in the cytoplasmic domain and that it forms homodimers through cis-interaction on the cell surface. The subcellular localization of hepaCAM appears density-dependent; in well spread cells, hepaCAM is distributed to cell protrusions, whereas in confluent cells, hepaCAM is predominantly accumulated at the sites of cell-cell contacts on the cell membrane. In polarized cells, hepaCAM is recruited to the lateral and basal membranes, and lacking physical interaction, hepaCAM is shown to co-localize with E-cadherin at the lateral membrane. Cell adhesion and motility assays demonstrated that hepaCAM increased cell spreading on the matrices fibronectin and matrigel, delayed cell detachment, and enhanced wound healing. Furthermore, when the cytoplasmic domain was deleted, hepaCAM mutants did not affect cell surface localization and dimer formation. Cell-matrix adhesion, however, was less significantly increased, and cell motility was almost unchanged when compared with the effect of the wild-type hepaCAM. Taken together, the cytoplasmic domain of hepaCAM is essential to its function on cell-matrix interaction and cell motility.

HEPN1, a novel gene that is frequently down-regulated in hepatocellular carcinoma, suppresses cell growth and induces apoptosis in HepG2 cells.

BACKGROUND/AIMS: Examining genes associated with human hepatocellular carcinoma (HCC) by subtractive hybridisation, we identified a novel transcript, designated as HEPN1, in non-tumorous liver. In this study, we aimed to evaluate HEPN1 gene expression in HCC patients, to characterise and to explore the functional significance of HEPN1 in vitro. METHODS: One-step reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR were employed to determine HEPN1 expression in 23 paired (HCC and the adjacent non-HCC) liver specimens. Sequence analyses were performed by bioinformatics. Transfection studies were carried out by expressing HEPN1, V5-fused HEPN1, and green fluorescent protein-fused HEPN1, individually, in HepG2 cells. RESULTS: Significant downregulation of HEPN1 (P<0.0001) was detected in 22/23 of HCC patients tested. Gene HEPN1 maps to chromosome 11q24.2; and the predicted gene product, a 10-kDa peptide with 88 amino acids, has no homology to known proteins. When transfected into HepG2 cells, HEPN1 reduced cell viability to 37.5+/-2.5% (P=0.001), and induced apoptosis with typical morphological changes as demonstrated by microscopy and Annexin V assay. CONCLUSIONS: Our data show that HEPN1 is frequently silenced in HCC, and that exogenous HEPN1 exhibits antiproliferative effect on HepG2 cells, suggesting that silencing of HEPN1 may be associated with carcinogenesis of hepatocytes.

Molecular characterization of hepatitis B virus surface antigen mutants in Singapore patients with hepatocellular carcinoma and hepatitis B virus carriers negative for HBsAg but positive for anti-HBs and anti-HBc.

BACKGROUND AND AIMS: Mutations on the a-determinant of hepatitis B virus surface antigen (HBsAg), capable of escaping detection and vaccination, are identified in HBsAg-positive/anti-HBs-positive vaccinated infants. We studied the prevalence of these mutants in HBsAg-negative/anti-HBc-positive chronic HBV carriers and patients with hepatocellular carcinoma (HCC). METHODS: DNA sequence coding for the antigenic a-determinant of HBsAg was amplified from either HCC genomic DNA or serum samples of the selected patients and sequenced. The replicative mutant genomes were reconstituted in vitro and their reactivity to commercial kits measured. RESULTS: Mutations within and/or outside the a-determinant were identified in patients seronegative for HBsAg. They were then reconstituted in vitro and transiently transfected into HepG2 cells. Culture medium containing secreted HBV viral particles was collected and assayed for their binding to commercial kits. Drastic decrease of reactivity to these kits was seen with most of the identified mutations, including those located outside the a-determinant. CONCLUSION: The existence of a more complex antigenic structure of HBsAg is indicated by the decreased reactivity to detection of mutations, some of which are outside the a-determinant, escape vaccination and may persist in seronegative patients. The high proportion of HBsAg mutants that are integrated in HCC genomes suggests a role of these mutants in hepatocarcinogenesis, possibly leading to mutant HBV-related HCC.