Type VIII collagen modulates TGF-β1-induced proliferation of mesangial cells

Si-Wu-Tang improves liver fibrosis by restoring liver sinusoidal endothelial cell functionality and reducing communication with hepatic stellate cells

BACKGROUND

Liver fibrosis is a complex reparative process in response to chronic liver injuries, with limited effective therapeutic options available in clinical practice. During liver fibrosis, liver sinusoidal endothelial cells (LSECs) undergo phenotypic changes and also play a role in modulating cellular communications. Si-Wu-Tang (SWT), a traditional Chinese herbal remedy, has been extensively studied for its effectiveness in treating hematological, gynecological and hepatic diseases.

MATERIALS AND METHODS

The component of SWT were identified by ultra-high-performance liquid chromatography (UHPLC). After establishing bile duct ligation (BDL)-induced liver fibrosis mice model and VEGFA-stimulated LSEC model, we invested the mechanism of SWT through RNA sequencing combined with molecular biology techniques.

RESULTS

SWT significantly improved the sinusoidal permeability and liver fibrosis induced by BDL and effectively regulated pathological processes in LSECs, such as angiogenesis, cell adhesion, basement membrane formation and defenestration. The anti-fibrosis effects of SWT were attributed to the inhibition on LSEC adhesion via COL8A1, on LSEC angiogenesis via IL-1β and the induction of LSEC defenestration by OLR1. Additionally, SWT disrupted the intercellular crosstalk between LSECs and hepatic stellate cells (HSCs) driven by IL-1β, thus alleviating liver fibrosis.

CONCLUSION

SWT collectively ameliorated liver fibrosis by inhibiting the COL8A1/IL-1β/OLR1 pathways associated with LSEC angiogenesis, adhesion and defenestration, as well as suppressing LSEC secretion of IL-1β to reduce HSC activation.

Collagen VIII in vascular diseases

Collagens have dual functions in the extracellular matrix (ECM), acting as both structural components and signaling molecules in matricellular communication. Although collagen molecules share a common triple helix motif, the supramolecular organization helps classify them into nearly 30 different types of collagens. Collagen type VIII is a non-fibrillar, short-chain, network-forming collagen that is expressed throughout the vasculature. Collagen VIII expression is aberrant in cardiovascular, lung, and renal disease, as well as in several different types of cancer. It plays active roles in angiogenesis, vessel injury repair, maintenance of arterial compliance, atherosclerotic plaque formation and stability modulation, fibrosis, and ECM remodeling. This review presents an overview of the characteristics of collagen VIII in vascular-related disorders, from clinical significance to laboratory studies, with a major focus on highlighting the signaling properties of collagen VIII in the vascular ECM. The expression patterns of collagen VIII in human diseases and experimental animal models highlight the protein's important yet underexplored functions. A deeper understanding of its mechanisms and downstream signaling pathways may pave the way for translational and tissue engineering applications of collagen VIII.

Exploring single-cell RNA sequencing as a decision-making tool in the clinical management of Fuchs' endothelial corneal dystrophy

Single-cell RNA sequencing (scRNA-seq) has enabled the identification of novel gene signatures and cell heterogeneity in numerous tissues and diseases. Here we review the use of this technology for Fuchs' Endothelial Corneal Dystrophy (FECD). FECD is the most common indication for corneal endothelial transplantation worldwide. FECD is challenging to manage because it is genetically heterogenous, can be autosomal dominant or sporadic, and progress at different rates. Single-cell RNA sequencing has enabled the discovery of several FECD subtypes, each with associated gene signatures, and cell heterogeneity. Current FECD treatments are mainly surgical, with various Rho kinase (ROCK) inhibitors used to promote endothelial cell metabolism and proliferation following surgery. A range of emerging therapies for FECD including cell therapies, gene therapies, tissue engineered scaffolds, and pharmaceuticals are in preclinical and clinical trials. Unlike conventional disease management methods based on clinical presentations and family history, targeting FECD using scRNA-seq based precision-medicine has the potential to pinpoint the disease subtypes, mechanisms, stages, severities, and help clinicians in making the best decision for surgeries and the applications of therapeutics. In this review, we first discuss the feasibility and potential of using scRNA-seq in clinical diagnostics for FECD, highlight advances from the latest clinical treatments and emerging therapies for FECD, integrate scRNA-seq results and clinical notes from our FECD patients and discuss the potential of applying alternative therapies to manage these cases clinically.

Protopanaxadiol improves lupus nephritis by regulating the PTX3/MAPK/ERK1/2 pathway

Lupus nephritis (LN) is a kidney disease that occurs after systemic lupus erythematosus (SLE) affects the kidneys. Pentraxin 3 (PTX3) is highly expressed in the serum of patients with LN. Renal PTX3 deposition is directly related to clinical symptoms such as proteinuria and inflammation. The excessive proliferation of mesangial cells (MCs) is one of the representative pathological changes in the progression of LN, which is closely related to its pathogenesis. Protopanaxadiol (PPD) is the main component of ginsenoside metabolism and has not been reported in LN. The aim of this study was to investigate the relationship between PTX3 and mesangial cell proliferation and to evaluate the potential role and mechanism of PPD in improving LN. PTX3 is highly expressed in the kidneys of LN patients and LN mice and is positively correlated with renal pathological indicators, including proteinuria and PCNA. The excessive expression of PTX3 facilitated the proliferation of MCs, facilitated the activation of the MAPK/ERK1/2 signaling pathway, and increased the expression of HIF-1α. Further studies showed that PPD can effectively inhibit the abnormal proliferation of MCs with high expression of PTX3 and significantly improve LN symptoms such as proteinuria in MRL/lpr mice. The mechanism may be related to the inhibition of the PTX3/MAPK/ERK1/2 pathway. In this study, both in vitro, in vivo, and clinical sample results show that PTX3 is involved in the regulation of MCs proliferation and the early occurrence of LN. Natural active compound PPD can improve LN by regulating the PTX3/MAPK/ERK1/2 pathway.

Interaction of circulating TGFβ regulatory miRNAs in different severity of diabetic kidney disease

AIMS

To explore the interaction of TGFβ regulatory microRNAs (miRNAs) with different severities of diabetic kidney disease (DKD).

METHODS

According to different UACR (30 and 300 mg/g), 436 subjects were included, and high glucose induced RMCs were cultured. Real-time PCR, ELISA, and automatic biochemical analysis were used to measure miRNAs, TGFβ1, and other biochemical indicators in serum and RMCs. Target genes of miRNA were predicted and visualised by bioinformatics.

RESULTS

HbA1c, TGFβ1, miR-217, and miR-224 in T2DM patients increased with UACR, while miR-192 and miR-216a decreased. Ln UACR was positively correlated with HbA1c, TGFβ1, miR-217, and miR-224, and negatively correlated with miR-192 and miR-216a. High glucose and TGFβ1 affected miRNAs and these miRNAs affected each other. The miRNA target genes mainly revolve around PTEN, PI3K/Akt, and MAPK signalling pathways.

CONCLUSION

TGFβ regulatory miRNAs and different severity of DKD have a potential interaction regulating fibrosis through PTEN, PI3K/Akt, and MAPK pathways.

The Role of Collagen VIII in the Aging Mouse Kidney

The gradual loss of kidney function due to increasing age is accompanied by structural changes such as fibrosis of the tissue. The underlying molecular mechanisms are complex, but not yet fully understood. Non-fibrillar collagen type VIII (COL8) could be a potential factor in the fibrosis processes of the aging kidney. A pathophysiological significance of COL8 has already been demonstrated in the context of diabetic kidney disease, with studies showing that it directly influences both the development and progression of renal fibrosis occurring. The aim of this study was to investigate whether COL8 impacts age-related micro-anatomical and functional changes in a mouse model. The kidneys of wild-type (Col8-wt) and COL8-knockout (Col8-ko) mice of different age and sex were characterized with regard to the expression of molecular fibrosis markers, the development of nephrosclerosis and renal function. The age-dependent regulation of COL8 mRNA expression in the wild-type revealed sex-dependent effects that were not observed with collagen IV (COL4). Histochemical staining and protein analysis of profibrotic cytokines TGF-β1 (transforming growth factor) and CTGF (connective tissue growth factor) in mouse kidneys showed significant age effects as well as interactions of the factors age, sex and Col8 genotype. There were also significant age and Col8 genotype effects in the renal function data analyzed by urinary cystatin C. In summary, the present study shows, for the first time, that COL8 is regulated in an age- and sex-dependent manner in the mouse kidney and that the expression of COL8 influences the severity of age-induced renal fibrosis and function.

FGF21 and autophagy coordinately counteract kidney disease progression during aging and obesity

Chronic kidney disease (CKD) has reached epidemic proportions worldwide, partly due to the increasing population of elderly and obesity. Macroautophagy/autophagy counteracts CKD progression, whereas autophagy is stagnated owing to lysosomal overburden during aging and obesity, which promotes CKD progression. Therefore, for preventing CKD progression during aging and obesity, it is important to elucidate the compensation mechanisms of autophagy stagnation. We recently showed that FGF21 (fibroblast growth factor 21), which is a prolongevity and metabolic hormone, is induced by autophagy deficiency in kidney proximal tubular epithelial cells (PTECs); however, its pathophysiological role remains uncertain. Here, we investigated the interplay between FGF21 and autophagy and the direct contribution of endogenous FGF21 in the kidney during aging and obesity using PTEC-specific fgf21- and/or atg5-deficient mice at 24 months (aged) or under high-fat diet (obese) conditions. PTEC-specific FGF21 deficiency in young mice increased autophagic flux due to increased demand of autophagy, whereas fgf21-deficient aged or obese mice exacerbated autophagy stagnation due to severer lysosomal overburden caused by aberrant autophagy. FGF21 was robustly induced by autophagy deficiency, and aged or obese PTEC-specific fgf21- and atg5-double deficient mice deteriorated renal histology compared with atg5-deficient mice. Mitochondrial function was severely disturbed concomitant with exacerbated oxidative stress and downregulated TFAM (transcription factor A, mitochondrial) in double-deficient mice. These results indicate that FGF21 is robustly induced by autophagy disturbance and protects against CKD progression during aging and obesity by alleviating autophagy stagnation and maintaining mitochondrial homeostasis, which will pave the way to a novel treatment for CKD.

In silico prediction and experimental validation to reveal the protective mechanism of Puerarin against excessive extracellular matrix accumulation through inhibiting ferroptosis in diabetic nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Puerarin (PUR) isolated from the root of Pueraria lobata (Willd.) Ohwi is considered as one of the main medicines to alleviate asthenic splenonephro-yang of diabetic nephropathy (DN). Whereas, the exact mechanism of Puerarin on diabetic nephropathy is still unclear.

AIM OF STUDY

In this study, we aimed to investigate the protective effects of PUR on type 2 diabetic nephropathy in vivo, in silico and in vitro, as well as unveil the underlying mechanism through inhibiting ferroptosis.

MATERIALS AND METHODS

In vivo, blood glucose and lipid, renal function, kidney histology and immunohistochemistry analysis were used to vindicate the protective effects of PUR on diabetic nephropathy in type 2 DN rat model. In silico, pharmacophore matching and enrichment analysis were adopted to predict the potential mechanism of PUR on DN. In vitro, we utilized high glucose stress to induce impairment in glomerular mesangial cells (GMCs) as diabetic nephropathy cell model. Cell count kit-8 (CCK-8) was used to observe cell viability. qPCR, Western blot, immunofluorescence staining and flow cytometry were used to evaluate the effect of PUR on the generation of extracellular matrix (ECM), ferroptosis and iron homeostasis in vitro and in vivo.

RESULTS

PUR markedly improved glucose and lipid metabolism, as well as alleviated renal dysfunction in diabetic nephropathy rats. Pharmacophore matching and enrichment analysis predicted the anti-DN effect of PUR may correlate with ECM. Experimental validation suggested that PUR treatment could inhibit the generation of ECM to alleviate high-glucose-induced cell impairments, suppressing ROS production and excessive collagen fiber accumulation in GMSs, and reduce mesangial matrix expansion and renal fibrosis in type 2 DN rats. Further study suggested that PUR protected GMCs against ferroptosis via reducing LDH release and GSH disruption, suppressing key regulators of two pathways for ferroptosis execution. Moreover, PUR also maintained iron metabolism hemostasis by regulating iron transportation proteins, iron exporter proteins, and iron storage proteins and reducing intracellular iron in type 2 DN rats.

CONCLUSION

PUR inhibited excessive ECM accumulation to protect against type 2 diabetic nephropathy, which meditated by regulating iron homeostasis and mitigating ferroptosis. This study provides promising therapeutics for diabetic nephropathy treatment.

Dapagliflozin can alleviate renal fibrosis in rats with streptozotocin‑induced type 2 diabetes mellitus

The aim of the present study was to explore the effects of Dapagliflozin on renal fibrosis in streptozotocin (STZ)-induced type 2 diabetes mellitus (T2DM) rats, and to determine the underlying mechanism of action. A total of 24 SPF male SD rats were randomly divided into 4 groups: A normal (Control) group, model group (STZ-induced T2DM rats), Dapagliflozin group (STZ-induced T2DM rats treated with 1 mg/kg Dapagliflozin), and a metformin group (STZ-induced T2DM rats treated with 200 mg/kg metformin), with 6 rats per a group. Peripheral blood and renal tissues were collected from these rats, and the renal indices of each group were examined. The fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), blood urea nitrogen (BUN), and serum creatinine (SCr) of rats were detected. After 24 h, the urine was collected and the urine protein levels were measured. Hematoxylin and eosin staining was used to detect histological changes in the rat kidney; Masson staining was used to observe the degree of fibrosis in rat renal tissues; and western blot was performed to determine the expression levels of α-smooth muscle actin (SMA), vimentin, E-cadherin, TGF-β1, Smad7, and p-Smad3 in rat renal tissues. Dapagliflozin effectively inhibited the increase in FBG and HbA1c levels in diabetic mice, reduced renal tissue damage, reduced the renal index values, reduced collagen deposition in the glomerulus and interstitial area, and reduced the proliferation of glomerular mesangial cells. In addition, Dapagliflozin significantly lowered the levels of BUN, SCr, and 24-h urine protein, decreased the protein expression of α-SMA, vimentin, TGF-β1, and p-Smad3, and increased the protein expression levels of E-cadherin and Smad7. Together, these results showed that Dapagliflozin alleviated renal fibrosis in STZ-induced T2DM rats, and its mechanism of action may be related to the inhibition of the TGF-β1/Smad pathway.

Understanding the relationship between circulating lipids and risk of chronic kidney disease: a prospective cohort study and large-scale genetic analyses

BACKGROUND

This study aims to comprehensively investigate the phenotypic and genetic relationships between four common lipids (high-density lipoprotein cholesterol, HDL-C; low-density lipoprotein cholesterol, LDL-C; total cholesterol, TC; and triglycerides, TG), chronic kidney disease (CKD), and estimated glomerular filtration rate (eGFR).

METHODS

We first investigated the observational association of lipids (exposures) with CKD (primary outcome) and eGFR (secondary outcome) using data from UK Biobank. We then explored the genetic relationship using summary statistics from the largest genome-wide association study of four lipids (N = 1,320,016), CKD (Ncase = 41,395, Ncontrol = 439,303), and eGFR(N = 567,460).

RESULTS

There were significant phenotypic associations (HDL-C: hazard ratio (HR) = 0.76, 95%CI = 0.60-0.95; TG: HR = 1.08, 95%CI = 1.02-1.13) and global genetic correlations (HDL-C: [Formula: see text] = - 0.132, P = 1.00 × 10-4; TG: [Formula: see text] = 0.176; P = 2.66 × 10-5) between HDL-C, TG, and CKD risk. Partitioning the whole genome into 2353 LD-independent regions, twelve significant regions were observed for four lipids and CKD. The shared genetic basis was largely explained by 29 pleiotropic loci and 36 shared gene-tissue pairs. Mendelian randomization revealed an independent causal relationship of genetically predicted HDL-C (odds ratio = 0.91, 95%CI = 0.85-0.98), but not for LDL-C, TC, or TG, with the risk of CKD. Regarding eGFR, a similar pattern of correlation and pleiotropy was observed.

CONCLUSIONS

Our work demonstrates a putative causal role of HDL-C in CKD and a significant biological pleiotropy underlying lipids and CKD in populations of European ancestry. Management of low HDL-C levels could potentially benefit in reducing the long-term risk of CKD.

Kidney fibrosis: from mechanisms to therapeutic medicines

Chronic kidney disease (CKD) is estimated to affect 10-14% of global population. Kidney fibrosis, characterized by excessive extracellular matrix deposition leading to scarring, is a hallmark manifestation in different progressive CKD; However, at present no antifibrotic therapies against CKD exist. Kidney fibrosis is identified by tubule atrophy, interstitial chronic inflammation and fibrogenesis, glomerulosclerosis, and vascular rarefaction. Fibrotic niche, where organ fibrosis initiates, is a complex interplay between injured parenchyma (like tubular cells) and multiple non-parenchymal cell lineages (immune and mesenchymal cells) located spatially within scarring areas. Although the mechanisms of kidney fibrosis are complicated due to the kinds of cells involved, with the help of single-cell technology, many key questions have been explored, such as what kind of renal tubules are profibrotic, where myofibroblasts originate, which immune cells are involved, and how cells communicate with each other. In addition, genetics and epigenetics are deeper mechanisms that regulate kidney fibrosis. And the reversible nature of epigenetic changes including DNA methylation, RNA interference, and chromatin remodeling, gives an opportunity to stop or reverse kidney fibrosis by therapeutic strategies. More marketed (e.g., RAS blockage, SGLT2 inhibitors) have been developed to delay CKD progression in recent years. Furthermore, a better understanding of renal fibrosis is also favored to discover biomarkers of fibrotic injury. In the review, we update recent advances in the mechanism of renal fibrosis and summarize novel biomarkers and antifibrotic treatment for CKD.

Stages of preadipocyte differentiation: biomarkers and pathways for extracellular structural remodeling

BACKGROUND

This study utilized bioinformatics to analyze the underlying biological mechanisms involved in adipogenic differentiation, synthesis of the extracellular matrix (ECM), and angiogenesis during preadipocyte differentiation in human Simpson-Golabi-Behmel syndrome at different time points and identify targets that can potentially improve fat graft survival.

RESULTS

We analyzed two expression profiles from the Gene Expression Omnibus and identified differentially expressed genes (DEGs) at six different time points after the initiation of preadipocyte differentiation. Related pathways were identified using Gene Ontology/Kyoto Encyclopedia of Genes and Genomes analyses and Gene Set Enrichment Analysis (GSEA). We further constructed a protein-protein interaction (PPI) network and its central genes. The results showed that upregulated DEGs were involved in cell differentiation, lipid metabolism, and other cellular activities, while downregulated DEGs were associated with angiogenesis and development, ECM tissue synthesis, and intercellular and intertissue adhesion. GSEA provided a more comprehensive basis, including participation in and positive regulation of key pathways of cell metabolic differentiation, such as the "peroxisome proliferator-activated receptor signaling pathway" and the "adenylate-activated protein kinase signaling pathway," a key pathway that negatively regulates pro-angiogenic development, ECM synthesis, and adhesion.

CONCLUSIONS

We identified the top 20 hub genes in the PPI network, including genes involved in cell differentiation, ECM synthesis, and angiogenesis development, providing potential targets to improve the long-term survival rate of fat grafts. Additionally, we identified drugs that may interact with these targets to potentially improve fat graft survival.

Antifibrotic effects of Quercetin on TGF-β1-induced vocal fold fibroblasts

OBJECTIVE

To investigate the effects of Quercetin on vocal fold fibroblasts induced by TGF-β1 and vocal fold injury.

METHODS

The effects of Quercetin on collagen type I (COL-I), collagen type III (COL-III), and fibronectin (FN) expressions in transforming growth factor-β1 (TGF-β1)-induced human vocal fold fibroblasts were examined by the quantitative reverse transcription-polymerase chain reaction and the enzyme-linked immunosorbent assay. The Cell Counting Kit-8 was used to assess the influence of Quercetin on cell proliferation. A rat vocal fold injury model was developed. These rats were divided into a control group, a model group, and a Quercetin group. Pathorphological observations from Hematoxylin-eosin staining, the density of fibroblasts, and hypertrophic index were compared among the three groups.

RESULTS

Compared with cells untreated with TGF-β1, the mRNA and protein expression levels of COL-I, COL-II, and FN and proliferation ability in TGF-β1-induced human vocal fold fibroblasts were increased (all P<0.05). Compared with human vocal fold fibroblasts induced by TGF-β1, the mRNA and protein expression levels of COL-I, COL-II, and FN and proliferation ability in TGF-β1-induced human vocal fold fibroblasts following Quercetin stimulation were decreased (all P<0.05). There were no statistical differences between human vocal fold fibroblasts treated with or without Quercetin regarding cell proliferation and COL-I, COL-II, and FN expressions. Compared with the model group, Quercetin suppressed the fibrosis of the vocal fold following injury and the protein levels of COL-I, COL-II, and FN in tissue samples (all P<0.001). The density of fibroblasts and hypertrophic index in the vocal fold scar from the Quercetin group were lower than those in the model group (all P<0.05).

CONCLUSIONS

Quercetin inhibited TGF-β1-induced fibrotic changes and proliferation in human vocal fold fibroblasts and had an antifibrotic effect in vocal fold after injuries.

Molecular programs associated with glomerular hyperfiltration in early diabetic kidney disease

Hyperfiltration is a state of high glomerular filtration rate (GFR) observed in early diabetes that damages glomeruli, resulting in an iterative process of increasing filtration load on fewer and fewer remaining functional glomeruli. To delineate underlying cellular mechanisms of damage associated with hyperfiltration, transcriptional profiles of kidney biopsies from Pima Indians with type 2 diabetes with or without early-stage diabetic kidney disease were grouped into two hyperfiltration categories based on annual iothalamate GFR measurements. Twenty-six participants with a peak GFR measurement within two years of biopsy were categorized as the hyperfiltration group, and 26 in whom biopsy preceded peak GFR by over two years were considered pre-hyperfiltration. The hyperfiltration group had higher hemoglobin A1c, higher urine albumin-to-creatinine ratio, increased glomerular basement membrane width and lower podocyte density compared to the pre-hyperfiltration group. A glomerular 1240-gene transcriptional signature identified in the hyperfiltration group was enriched for endothelial stress response signaling genes, including endothelin-1, tec-kinase and transforming growth factor-β1 pathways, with the majority of the transcripts mapped to endothelial and inflammatory cell clusters in kidney single cell transcriptional data. Thus, our analysis reveals molecular pathomechanisms associated with hyperfiltration in early diabetic kidney disease involving putative ligand-receptor pairs with downstream intracellular targets linked to cellular crosstalk between endothelial and mesangial cells.

Zuogui Wan ameliorates high glucose-induced podocyte apoptosis and improves diabetic nephropathy in db/db mice

Zuogui Wan (ZGW), a well-known traditional Chinese medicine (TCM), has been used to nourish “Kidney-Yin” for a long time in China, implying a protective effect on the kidney. The aim of the present study is to investigate the effect of ZGW on high glucose-induced podocyte apoptosis and diabetic nephropathy (DN) in db/db mice. ZGW (1 g/kg⁻¹/day⁻¹) was administered intragastrically to db/db mice for 8 weeks. HPLC was used for identifying the components of ZGW, biochemical and histopathological approaches were used for evaluating its therapeutic effects, and cultured mouse podocytes were used for further exploring its underlying mechanism in vitro. ZGW improved renal function and podocyte loss and also normalized kidney reactive oxygen species production in db/db mice. The cytotoxicity of ZGW on mouse podocytes was assessed by the LDH assay. The effect of ZGW on podocyte viability and apoptosis was determined with CCK-8 and Annexin-V/PI staining by treatment with high glucose. ZGW attenuated podocyte apoptosis, and oxidative stress was detected by the peroxide-sensitive fluorescent probe 2′,7′-dichlorodihydrofluorescein diacetate (DCF-DA) staining in a dose-dependent manner. Furthermore, ZGW decreased the expression of caspase-3 and phospho-p38 in both the kidney cortex and high glucose-treated podocytes. Thus, our data from in vivo and in vitro studies demonstrated that ZGW improved renal injury in diabetes by inhibiting oxidative stress and podocyte apoptosis.

Immune Modulation by Myeloid-Derived Suppressor Cells in Diabetic Kidney Disease

Diabetic kidney disease (DKD) frequently leads to end-stage renal disease and other life-threatening illnesses. The dysregulation of glomerular cell types, including mesangial cells, endothelial cells, and podocytes, appears to play a vital role in the development of DKD. Myeloid-derived suppressor cells (MDSCs) exhibit immunoregulatory and anti-inflammatory properties through the depletion of L-arginine that is required by T cells, through generation of oxidative stress, interference with T-cell recruitment and viability, proliferation of regulatory T cells, and through the promotion of pro-tumorigenic functions. Under hyperglycemic conditions, mouse mesangial cells reportedly produce higher levels of fibronectin and pro-inflammatory cytokines. Moreover, the number of MDSCs is noticeably decreased, weakening inhibitory immune activities, and creating an inflammatory environment. In diabetic mice, immunotherapy with MDSCs that were induced by a combination of granulocyte-macrophage colony-stimulating factor, interleukin (IL)-1β, and IL-6, reduced kidney to body weight ratio, fibronectin expression, and fibronectin accumulation in renal glomeruli, thus ameliorating DKD. In conclusion, MDSCs exhibit anti-inflammatory activities that help improve renal fibrosis in diabetic mice. The therapeutic targeting of the proliferative or immunomodulatory pathways of MDSCs may represent an alternative immunotherapeutic strategy for DKD.

FGF21 and Chronic Kidney Disease

The global nephrology community recognizes the increasing burden of kidney disease and its poor health outcomes in the general population. Given this, strategies to establish early diagnosis, improve understanding of the natural course and develop novel therapeutic interventions to slow progression and reduce complications are encouraged. Fibroblast growth factor 21 (FGF21), a member of the endocrine FGF subfamily, has emerged as a master homeostasis regulator of local and systemic lipid, glucose and energy metabolism. In addition, FGF21 should be considered an autonomic and endocrine regulator of stress responses in general. Promising results has been shown in both dysmetabolic animal models and metabolic disease patients after pharmacological administration of FGF21 analogs. The association of FGF21 with renal function has been studied for more than ten years. However, the functional role of FGF21 in the kidney is still poorly understood. This review summarizes the biological effects of FGF21 and discusses what is currently known about this hormone and chronic kidney disease, highlighting important gaps that warrant further research.

COL8A2 Regulates the Fate of Corneal Endothelial Cells

Purpose

To investigate the effect of COL8A2 repression on corneal endothelial cells (CECs) in vitro and in vivo.

Methods

Cultured human CECs (hCECs) were transfected with COL8A2 siRNA (siCOL8A2), and the cell viability and proliferation rate were measured. The expression of cell proliferation–associated molecules was evaluated by Western blotting and real-time reverse transcription PCR. Cell shape, Wingless-INT (WNT) signaling, and mitochondrial oxidative stress were also measured. For in vivo experiments, siCOL8A2 was transfected into rat CECs (rCECs), and corneal opacity and corneal endothelium were evaluated.

Results

After transfection with siCOL8A2, COL8A2 expression was reduced (80%). Cell viability, cell proliferation rate, cyclin D1 expression, and the number of cells in the S-phase were reduced in siCOL8A2-treated cells. The cell attained a fibroblast-like shape, and SNAI1, pSMAD2, and β-catenin expression, along with mitochondrial mass and oxidative stress levels, were altered. Corneal opacity increased, and the CECs were changed in rats in the siCOL8A2 group.

Conclusions

COL8A2 is required to maintain normal wound healing and CEC function.

Phosphoproteomics of Acute Cell Stressors Targeting Exercise Signaling Networks Reveal Drug Interactions Regulating Protein Secretion

Exercise engages signaling networks to control the release of circulating factors beneficial to health. However, the nature of these networks remains undefined. Using high-throughput phosphoproteomics, we quantify 20,249 phosphorylation sites in skeletal muscle-like myotube cells and monitor their responses to a panel of cell stressors targeting aspects of exercise signaling in vivo. Integrating these in-depth phosphoproteomes with the phosphoproteome of acute aerobic exercise in human skeletal muscle suggests that co-administration of β-adrenergic and calcium agonists would activate complementary signaling relevant to this exercise context. The phosphoproteome of cells treated with this combination reveals a surprising divergence in signaling from the individual treatments. Remarkably, only the combination treatment promotes multisite phosphorylation of SERBP1, a regulator of Serpine1 mRNA stability, a pro-fibrotic secreted protein. Secretome analysis reveals that the combined treatments decrease secretion of SERPINE1 and other deleterious factors. This study provides a framework for dissecting phosphorylation-based signaling relevant to acute exercise.

Icariin Prevents Extracellular Matrix Accumulation and Ameliorates Experimental Diabetic Kidney Disease by Inhibiting Oxidative Stress via GPER Mediated p62-Dependent Keap1 Degradation and Nrf2 Activation

The present study aimed to determine whether icariin could attenuate type 1 diabetic nephropathy (T1DN) induced by streptozotocin (STZ) after 4 weeks or not. Therefore, its therapeutic effect on diabetic kidney disease was investigated in view of reactive oxygen (ROS) and extracellular matrix (ECM) generation in human glomerular mesangial cells under high glucose. To establish the participation and the key role of GPER and Nrf2 in ECM deposition, a combination of G15 (antagonist of GPER) or siGPER and siNrf2 were performed, respectively. The results showed that T1DN can be significantly inhibited by oral icariin, evidenced by improvement of 24 h urinary volume, 24 h proteinuria, microalbuminuria, and histopathological changes of kidney. Icariin decreased the levels of intracellular superoxide anion, impeded the generation of fibronectin and increased the expression and activity of antioxidant enzymes in the human glomerular mesangial cells treated with high glucose. It acted as a GPER activator, increased dissociation of Nrf2/Keap1 complexes, combination of Keap1/p62 complexes, Nrf2 translocation to nuclear, Nrf2/ARE DNA binding activity, and ARE luciferase reporter gene activity in glomerular mesangial cells. The Nrf2 inhibitor ML385 or siNrf2 obviously abolished extracellular matrix (ECM) generation inhibited by icariin. Furthermore, icariin-induced Nrf2 activation was mainly dependent on p62-mediated Keap1 degradation, which functions as an adaptor protein during autophagy. The GPER antagonist G15 and siGPER obviously abolished the above effects by icariin. Taken together, the present study demonstrated that the therapeutic effects of icariin on type 1 diabetic nephropathy in rats via GPER mediated p62-dependent Keap1 degradation and Nrf2 activation.

Changes in the biochemical, hematological and histopathological parameters in STZ-Induced diabetic rats and the ameliorative effect of Kigelia africana fruit extract

Background

Biochemical, hematological and histological changes are major observable clinical and pathological factors associated with Diabetes mellitus. Derangement in the levels of these parameters increases the risk of the development of complications. In another hand, gastrointestinal intolerance due to the development of lactic acidosis on the gastrointestinal tract and the intestinal microbiome is the toxic side effect of various synthetic antidiabetic agents. The use of Kigelia africana fruit extract for the treatment of diabetes has been scientifically validated. This study therefore aimed at investigating changes in the biochemical, hematological and histological parameters as well as the determination of the functional groups present in the hexane fraction of the fruit.

Methods

The fruits were extracted with ethanol and partitioned with n-hexane to obtain the hexane fraction. Diabetic rats induced with streptozotocin (STZ) were divided into 5 groups of 5 animals each and treated with 100, 200 and 400 mg/kg body weight (BW) hexane fraction alongside reference standard; glibenclamide. Fasting blood glucose levels and their body weights were monitored weekly. Animals were sacrificed at the end of 28-day treatment. Blood, liver, and kidney were collected for biochemical, hematological and histopathological analyses. Fourier transform infrared resonance (FTIR) spectroscopic analysis was carried out on the hexane fraction for functional group determination.

Results

The hexane fraction of K. africana fruit extract decreased fasting blood glucose (FBG) levels significantly with ameliorative effects on the hematological parameters such as packed cell volume (PCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and red blood cells (RBC) etc. There were significant regenerative differences in the biochemical activities as well as the renal cortex and midzone sections of the rat's kidney and liver when compared with untreated diabetic rats. The presence of polyphenolic functional groups via FTIR analysis suggested high antioxidant activities of the fruit extract.

Conclusion

The use of Kigelia africana fruit extracts protects against biochemical, hematological and histological changes that are injurious to diabetic patients. Therefore, Kigelia africana fruit is a good hepatic- and nephroprotective agent and has a hemato-protective ability.

Fibroblast growth factor 21; review on its participation in vascular calcification pathology

Vascular calcification (VC) is an independent cardiovascular event and also a complication commonly found in chronic kidney disease (CKD) and diabetic patients. The mechanisms underpinning pathophysiology of VC is yet to be fully understood. Nevertheless, certain processes are generally believed to participate in its onset and progression. VC pathology is characterized by disequilibrium in the amount of natural inhibitors and active inducers of VC process. The imbalance may favor ectopic deposition of calcium-phosphate in form of hydroxyapatite in media or intima tunica compartments of blood vessels. This eventually could trigger phenotypic switch of smooth muscle cells to osteoblasts related cells. Thus, VSMC phenotypic trans-differentiation is currently considered as one of the hallmarks of VC. At the moment, there is no approved treatment. Fibroblast growth factors (FGFs) are a protein family that participates in varieties of biological processes. More recently, FGF21 seems to be gaining more attention with recent findings showing its anti-calcifying efficacy. In this review, the aim is to point out specific processes involved in VC and also to highlight the participation of FGF21 in the pathology of vascular calcification.

Glomerular mesangial cell and podocyte injuries in diabetic nephropathy

Diabetic nephropathy is one of the leading causes of end-stage renal disease and creates heavy healthcare burdens globally. Dysfunction of mesangial cells and podocytes contributes to diabetic nephropathy. Dysregulation of signaling involved in renal development and regeneration may cause diabetic kidney damages. Growing evidences suggest the importance of dysregulated dickkopf-1 (DKK1)/Wnt/ β-catenin signaling pathways in the pathogenesis of diabetic glomerular injuries. The inhibition of Wnt signaling in injured mesangial cells is likely attributed to the high glucose-induced Ras/Rac1 dependent superoxide formation. When DKK1, the cellular inhibitor of Wnt signaling, binds to the Kremen-2 receptor, depositions of extracellular matrix increase in the mesangium of diabetic kidneys. Additionally, reactivation of Notch-1 signaling has been implicated in podocytopathy during diabetic proteinuria development. Knocking down Notch-1 alleviates vascular endothelial growth factor (VEGF) expression, nephrin repression and proteinuria in diabetic kidneys. It is also found that epigenetic modulations by histone deacetylase 4 (HDAC4) and miR-29a could lead to diabetic nephropathy. High glucose increases the expression of HDAC4, which causes deacetylation with subsequent ubiquitination of nephrin. Overexpression of miR-29a in diabetic transgenic mice would decrease the expression of HDAC4 and stabilize nephrin. Surprisingly, reprogramming or reactivation of signaling involved in renal development or regeneration often brings about diabetic glomerular sclerosis in mesangial cells and podocytes. Better knowledge about modifications of embryonic stem cell signaling will have a chance to implement strategically focused pharmacological research programs aiming to the development of new drugs for diabetic kidney injuries.

FGF21 is induced in cisplatin nephrotoxicity to protect against kidney tubular cell injury

Cisplatin, a widely used cancer therapy drug, induces nephrotoxicity or acute kidney injury (AKI), but the underlying mechanism remains unclear, and renal protective approaches are not available. Fibroblast growth factor (FGF)21 is an endocrine factor that regulates glucose uptake, metabolism, and energy expenditure. However, recent work has also implicated FGF21 in cellular stress response under pathogenic conditions. The role and regulation of FGF21 in AKI are unclear. Here, we show that FGF21 was dramatically induced during cisplatin treatment of renal tubular cells in vitro and mouse kidneys in vivo. The inductive response was suppressed by pifithrin (a pharmacological inhibitor of P53), suggesting a role of P53 in FGF21 induction. In cultured renal tubular cells, knockdown of FGF21 aggravated cisplatin-induced apoptosis, whereas supplementation of recombinant FGF21 was protective. Consistently, recombinant FGF21 alleviated cisplatin-induced kidney dysfunction, tissue damage, and tubular apoptosis in mice. Mechanistically, FGF21 suppressed P53 induction and activation during cisplatin treatment. Together, these results indicate that FGF21 is induced during cisplatin nephrotoxicity to protect renal tubules, and recombinant FGF21 may have therapeutic potential.-Li, F., Liu, Z., Tang, C., Cai, J., Dong, Z. FGF21 is induced in cisplatin nephrotoxicity to protect against kidney tubular cell injury.

Upregulation of distinct collagen transcripts in post-surgery scar tissue: a study of conjunctival fibrosis

Excessive accumulation of collagen is often used to assess the development of fibrosis. This study aims to identify collagen genes that define fibrosis in the conjunctiva following glaucoma filtration surgery (GFS). Using the mouse model of GFS, we have identified collagen transcripts that were upregulated in the fibrotic phase of wound healing via RNA-seq. The collagen transcripts that were increased the most were encoded by Col8a1, Col11a1 and Col8a2. Further analysis of the Col8a1, Col11a1 and Col8a2 transcripts revealed their increase by 67-, 54- and 18-fold, respectively, in the fibrotic phase, compared with 12-fold for Col1a1, the most commonly evaluated collagen gene for fibrosis. However, only type I collagen was significantly upregulated at the protein level in the fibrotic phase. Type VIII and type I collagens colocalized in fibrous structures and in ACTA2-positive pericytes, and appeared to compensate for each other in expression levels. Type XI collagen showed low colocalization with both type VIII and type I collagens but can be found in association with macrophages. Furthermore, we show that both mouse and human conjunctival fibroblasts expressed elevated levels of the most highly expressed collagen genes in response to TGFβ2 treatment. Importantly, conjunctival tissues from individuals whose GF surgeries have failed due to scarring showed 3.60- and 2.78-fold increases in type VIII and I collagen transcripts, respectively, compared with those from individuals with no prior surgeries. These data demonstrate that distinct collagen transcripts are expressed at high levels in the conjunctiva after surgery and their unique expression profiles may imply differential influences on the fibrotic outcome.

Summary: As well as providing an objective quantitative measure, distinct collagen genes may further aid in the characterization and definition of the development of fibrosis.

Insights into Diabetic Kidney Disease Using Urinary Proteomics and Bioinformatics

A number of proteomic and peptidomic analyses of urine from diabetic subjects have been published in the quest for a biomarker that predicts progression of nephropathy. Less attention has been paid to the relationships between urinary proteins and the underlying biological processes revealed by the analyses. In this review, we focus on the biological processes identified by studying urinary proteins and protein-protein interactions at each stage of diabetic nephropathy to provide an overview of the events underlying progression of kidney disease reflected in the urine. In uncomplicated diabetes, proteomic/peptidomic analyses indicate that early activation of fibrotic pathways in the kidney occurs before the onset of microalbuminuria. In incipient nephropathy, when albumin excretion rates are abnormal, proteomic/peptidomic analyses suggest that changes in glomerular permselectivity and tubular reabsorption account, at least in part, for the proteins and peptides that appear in the urine. Finally, overt nephropathy is characterized by proteins involved in wound healing, ongoing fibrosis, and inflammation. These findings suggest that there is a spectrum of biological processes in the diabetic kidney and that assessing protein networks may be more informative than individual markers with respect to the stage of disease and the risk of progression.

New Altered Non-Fibrillar Collagens in Human Dilated Cardiomyopathy: Role in the Remodeling Process

Background

In dilated cardiomyopathy (DCM), cardiac failure is accompanied by profound alterations of extracellular matrix associated with the progression of cardiac dilation and left ventricular (LV) dysfunction. Recently, we reported alterations of non-fibrillar collagen expression in ischemic cardiomyopathy linked to fibrosis and cardiac remodeling. We suspect that expression changes in genes coding for non-fibrillar collagens may have a potential role in DCM development.

Objectives

This study sought to analyze changes in the expression profile of non-fibrillar collagen genes in patients with DCM and to examine relationships between cardiac remodeling parameters and the expression levels of these genes.

Methods and Results

Twenty-three human left ventricle tissue samples were obtained from DCM patients (n = 13) undergoing heart transplantation and control donors (n = 10) for RNA sequencing analysis. We found increased mRNA levels of six non-fibrillar collagen genes, such as COL4A5, COL9A1, COL21A1, and COL23A1 (P < 0.05 for all), not previously described in DCM. Protein levels of COL8A1 and COL16A1 (P < 0.05 for both), were correspondingly increased. We also identified TGF-β1 significantly upregulated and related to both COL8A1 and COL16A1. Interestingly, we found a significant relationship between LV mass index and the gene expression level of COL8A1 (r = 0.653, P < 0.05).

Conclusions

In our research, we identified new non-fibrillar collagens with altered expression in DCM, being COL8A1 overexpression directly related to LV mass index, suggesting that they may be involved in the progression of cardiac dilation and remodeling.

Protective effects of miR-29a on diabetic glomerular dysfunction by modulation of DKK1/Wnt/β-catenin signaling

Dysregulation of specific microRNAs or Wnt/β-catenin signaling pathway is critically implicated in the pathogenesis of various renal diseases. However, the relationship between microRNAs and Wnt/β-catenin signaling in diabetes-induced glomerular sclerosis remains unknown. Here, we found that decreased miR-29a expression and attenuated Wnt/β-catenin signaling were concomitantly detected in glomeruli of streptozotocin-induced diabetic mice. Gain of miR-29a function in diabetic mice substantially increased the expression of β-catenin and blocked the expressions of profibrotic gene markers, including DKK1 (a Wnt antagonist), TGF-β1 and fibronectin, in glomerular mesangium. Moreover, in the normal mice treated with miR-29a inhibitor, renal fibrosis was induced with an attenuated Wnt/β-catenin signaling activity. Consistently, the constructed miR-29a transgenic mice that supported sustained Wnt/β-catenin signaling had the ability to block the expressions of profibrotic genes after induction of diabetes. We also demonstrated that miR-29a acts as a positive regulator of Wnt/β-catenin signaling in cultured mesangial cells and functions to protect cell apoptosis and fibrosis. Importantly, we showed that activation of Wnt/β-catenin signaling in cultured mesangial cells by transfecting the β-catenin (Δ45) mutant or by a GSK-3β inhibitor reversely upregulated miR29a. Our findings suggest that the reciprocal relationship between miR-29a and DKK1/Wnt/β-catenin signaling may play an important part in protecting renal fibrogenesis.

The Orphan Nuclear Receptor ERRγ Regulates Hepatic CB1 Receptor-Mediated Fibroblast Growth Factor 21 Gene Expression

Background

Fibroblast growth factor 21 (FGF21), a stress inducible hepatokine, is synthesized in the liver and plays important roles in glucose and lipid metabolism. However, the mechanism of hepatic cannabinoid type 1 (CB1) receptor-mediated induction of FGF21 gene expression is largely unknown.

Results

Activation of the hepatic CB1 receptor by arachidonyl-2’-chloroethylamide (ACEA), a CB1 receptor selective agonist, significantly increased FGF21 gene expression. Overexpression of estrogen-related receptor (ERR) γ increased FGF21 gene expression and secretion both in hepatocytes and mice, whereas knockdown of ERRγ decreased ACEA-mediated FGF21 gene expression and secretion. Moreover, ERRγ, but not ERRα and ERRβ, induced FGF21 gene promoter activity. In addition, deletion and mutation analysis of the FGF21 promoter identified a putative ERRγ-binding motif (AGGTGC, a near-consensus response element). A chromatin immunoprecipitation assay revealed direct binding of ERRγ to the FGF21 gene promoter. Finally, GSK5182, an ERRγ inverse agonist, significantly inhibited hepatic CB1 receptor-mediated FGF21 gene expression and secretion.

Conclusion

Based on our data, we conclude that ERRγ plays a key role in hepatic CB1 receptor-mediated induction of FGF21 gene expression and secretion.

Up-regulation of Nrf2 is involved in FGF21-mediated fenofibrate protection against type 1 diabetic nephropathy

The lipid lowering medication, fenofibrate (FF), is a peroxisome proliferator-activated receptor-alpha (PPARα) agonist, possessing beneficial effects for type 2 diabetic nephropathy (DN). We investigated whether FF can prevent the development of type 1 DN, and the underlying mechanisms. Diabetes was induced by a single intraperitoneal injection of streptozotocin in C57BL/6J mice. Mice were treated with oral gavage of FF at 100mg/kg every other day for 3 and 6 months. Diabetes-induced renal oxidative stress, inflammation, apoptosis, lipid and collagen accumulation, and renal dysfunction were accompanied by significant decrease in PI3K, Akt, and GSK-3β phosphorylation as well as an increase in the nuclear accumulation of Fyn [a negative regulator of nuclear factor (erythroid-derived 2)-like 2 (Nrf2)]. All these adverse effects were significantly attenuated by FF treatment. FF also significantly increased fibroblast growth factor 21 (FGF21) expression and enhanced Nrf2 function in diabetic and non-diabetic kidneys. Moreover, FF-induced amelioration of diabetic renal damage, including the stimulation of PI3K/Akt/GSK-3β/Fyn pathway and the enhancement of Nrf2 function were abolished in FGF21-null mice, confirming the critical role of FGF21 in FF-induced renal protection. These results suggest for the first time that FF prevents the development of DN via up-regulating FGF21 and stimulating PI3K/Akt/GSK-3β/Fyn-mediated activation of the Nrf2 pathway.

The emerging role of fibroblast growth factor 21 in diabetic nephropathy

Diabetic nephropathy (DN), an important cause of end-stage renal diseases, brings about great social and economic burden. Due to the variable pathological changes and clinical course, the prognosis of DN is very difficult to predict. DN is also usually associated with enhanced genomic damage and cellular injury. Fibroblast growth factor 21 (FGF21), a nutritionally regulated hormone secreted mainly by the liver, plays a critical role in metabolism. Administration of FGF21 decreases blood glucose, triglyceride, and cholesterol levels, and improves insulin sensitivity, which is closely associated with the development and progression of glomerular diseases. In addition, FGF21 level was associated with renal function. However, the precise role of FGF21 in DN remains unclear. This review will give a comprehensive understanding of the underlying role of FGF21 and its possible interaction with other molecules in DN.

The role of fibroblast growth factor 21 in diabetes and its complications: A review from clinical perspective

Fibroblast growth factor 21 (FGF21) has been well-recognized as a metabolic hormone and a promising target for treatment of metabolic diseases. The level of endogenous FGF21 is elevated in patients with impaired glucose tolerance and progressively increased from patients with overt type 2 diabetes to those with micro- and macro-vascular complications, presumably as a compensation or response to the deterioration of metabolic imbalance. A few exploratory in vivo studies, including a recent clinical trial, showed that exogenous FGF21 mimetics targeting FGF21 signaling can attain beneficial metabolic effects not with-standing the already elevated ambient FGF21 levels. In addition, some clinically available pharmacologic agents such as fenofibrates and metformin may modulate energy and macronutrients metabolism by acting through FGF21. This review mainly focuses on the role of FGF21 in development, progression and treatment of type 2 diabetes from a clinical perspective.

Mind the gap: connexins and cell-cell communication in the diabetic kidney

Connexins, assembled as a hexameric connexon, form a transmembrane hemichannel that provides a conduit for paracrine signalling of small molecules and ions to regulate the activity and function of adjacent cells. When hemichannels align and associate with similar channels on opposing cells, they form a continuous aqueous pore or gap junction, allowing the direct transmission of metabolic and electrical signals between coupled cells. Regulation of gap junction synthesis and channel activity is critical for cell function, and a number of diseases can be attributed to changes in the expression/function of these important proteins. Diabetic nephropathy is associated with several complex metabolic and inflammatory responses characterised by defects at the molecular, cellular and tissue level. In both type 1 and type 2 diabetes, glycaemic injury of the kidney is the leading cause of end-stage renal failure, a consequence of multiple aetiologies, including increased deposition of extracellular matrix, glomerular hyperfiltration, albuminuria and tubulointerstitial fibrosis. In diabetic nephropathy, loss of connexin mediated cell-cell communication within the nephron may represent an early sign of disease; however, our current knowledge of the role of connexins in the diabetic kidney is sparse. This review highlights recent evidence demonstrating that maintenance of connexin-mediated cell-cell communication could benefit region-specific renal function in diabetic nephropathy and suggests that these proteins should be viewed as a tantalising novel target for therapeutic intervention.

Data mining reveals a network of early-response genes as a consensus signature of drug-induced in vitro and in vivo toxicity

Gene signatures of drug-induced toxicity are of broad interest, but they are often identified from small-scale, single-time point experiments, and are therefore of limited applicability. To address this issue, we performed multivariate analysis of gene expression, cell-based assays, and histopathological data in the TG-GATEs (Toxicogenomics Project-Genomics Assisted Toxicity Evaluation system) database. Data mining highlights four genes-EGR1, ATF3, GDF15 and FGF21-that are induced 2 h after drug administration in human and rat primary hepatocytes poised to eventually undergo cytotoxicity-induced cell death. Modelling and simulation reveals that these early stress-response genes form a functional network with evolutionarily conserved structure and intrinsic dynamics. This is underlined by the fact that early induction of this network in vivo predicts drug-induced liver and kidney pathology with high accuracy. Our findings demonstrate the value of early gene-expression signatures in predicting and understanding compound-induced toxicity. The identified network can empower first-line tests that reduce animal use and costs of safety evaluation.

Fibroblast growth factor 21 improves insulin resistance and ameliorates renal injury in db/db mice

Despite the emerging importance of fibroblast growth factor 21 (FGF21) as a metabolic hormone regulating energy balance, its direct effects on renal function remain unexplored. FGF21 was injected ip daily for 12 weeks into db/db mice. Compared with control vehicle injection, FGF21 treatment significantly improved lipid profiles and insulin resistance and resulted in significantly higher serum adiponectin levels. In contrast, serum insulin and 8-isoprostane levels were significantly decreased. Interestingly, FGF21 and its receptor components in the kidneys were found to be significantly up-regulated in db/db mice, which suggests an FGF21-resistant state. FGF21 treatment significantly down-regulated FGF21 receptor components and activated ERK phosphorylation. FGF21 administration also markedly decreased urinary albumin excretion and mesangial expansion and suppressed profibrotic molecule synthesis. Furthermore, FGF21 improved renal lipid metabolism and oxidative stress injury. In cultured renal cells, FGF21 was mainly expressed in mesangial cells, and knockdown of FGF21 expression by stealth small interfering RNA further aggravated high-glucose-induced profibrotic cytokine synthesis in mesangial cells. Our results suggest that FGF21 improves insulin resistance and protects against renal injury through both improvement of systemic metabolic alterations and antifibrotic effects in type 2 diabetic nephropathy. Targeting FGF21 could therefore provide a potential candidate approach for a therapeutic strategy in type 2 diabetic nephropathy.

High prevalence of eosinophilic esophagitis in patients with inherited connective tissue disorders

BACKGROUND

Eosinophilic esophagitis (EoE) is an emerging chronic inflammatory disease mediated by immune hypersensitization to multiple foods and strongly associated with atopy and esophageal remodeling.

OBJECTIVE

We provide clinical and molecular evidence indicating a high prevalence of EoE in patients with inherited connective tissue disorders (CTDs).

METHODS

We examined the rate of EoE among patients with CTDs and subsequently analyzed esophageal mRNA transcript profiles in patients with EoE with or without CTD features.

RESULTS

We report a cohort of 42 patients with EoE with a CTD-like syndrome, representing 0.8% of patients with CTDs and 1.3% of patients with EoE within our hospital-wide electronic medical record database and our EoE research registry, respectively. An 8-fold risk of EoE in patients with CTDs (relative risk, 8.1; 95% confidence limit, 5.1-12.9; χ(2)1 = 112.0; P < 10(-3)) was present compared with the general population. Esophageal transcript profiling identified a distinct subset of genes, including COL8A2, in patients with EoE and CTDs.

CONCLUSION

There is a remarkable association of EoE with CTDs and evidence for a differential expression of genes involved in connective tissue repair in this cohort. Thus, we propose stratification of patients with EoE and CTDs into a subset referred to as EoE-CTD.

Type VIII collagen signals via β1 integrin and RhoA to regulate MMP-2 expression and smooth muscle cell migration

The extracellular matrix signals and regulates the behavior of vascular cells during the pathogenesis of atherosclerosis. Type VIII collagen, a short chain collagen, is scarcely present in normal arteries, but is dramatically upregulated in atherosclerosis and after other types of vascular injury. Cell culture studies have revealed that this protein supports smooth muscle cell (SMC) adhesion and stimulates migration, however little is known about the signaling or the mechanisms by which this occurs. SMCs isolated from wild-type C57BL/6 and type VIII collagen deficient mice were studied using assays to measure chemotactic and haptotactic migration, and remodeling and contraction of 3-dimensional type I collagen gels. Col8(-/-) SMCs exhibited impairments in migration, and a strongly adhesive phenotype with prominent stress fibers, stable microtubules and pronounced central basal focal adhesions. The addition of exogenous type VIII collagen to the Col8(-/-) SMCs rescued the impairments in migration, and restored cytoskeletal architecture so that it was similar to Col8(+/+) cells. We measured elevated levels of active GTP-RhoA in the Col8(-/-) cells, and this too was reversed by treatment with exogenous type VIII collagen. We showed that type VIII collagen normally suppresses RhoA activation through a beta-1 integrin dependent mechanism. MMP-2 levels were reduced in the Col8(-/-) SMCs, and knockdown of MMP-2 in Col8(+/+) SMCs partially recapitulated the decreases in migration and 3D gel contraction seen in Col8(-/-) cells, showing that type VIII collagen-stimulated migration was dependent on MMP-2. Inhibition of Rho restored MMP-2 activity in the Col8(-/-) cells, and partially rescued migration, demonstrating that the elevations in RhoA activity were responsible for the suppression of migration of these cells. In conclusion, we have shown that type VIII collagen signals through beta-1 integrin receptors to suppress RhoA, allowing optimal configuration of the cytoskeleton, and the stimulation of MMP-2-dependent cell migration.

Interactions between FGF21 and BMP-2 in osteogenesis

Lifestyle-related diseases are increasing and the challenge to create innovative drugs to treat such diseases is a main focus in medical science research. Fibroblast growth factor 21 (FGF21) is a powerful modulator of glucose and lipid metabolism, and is an innovative candidate drug already in clinical trials for type 2 diabetes mellitus and obesity. Bone fragility and impaired fracture healing induced by such lifestyle-related conditions are also a growing problem. Bone morphogenic proteins (BMPs) are well known osteogenic growth factors, and BMP-2 is used to augment bone formation in difficult clinical situations. There are many documented interactions between the FGF and BMP family proteins, although the interaction between FGF21 and BMP-2 remains unknown. The aim of this study was to reveal the effect of FGF21 toward BMP-2-dependent osteogenic activity, using C2C12 cells as a model system. We found that FGF21 enhanced BMP-2-dependent transcription and osteogenesis in the C2C12 cell line, which was confirmed by alkaline phosphatase activity, matrix mineralization, and gene expression. Mechanistically, FGF21 enhanced BMP-2-induced intracellular signaling through Smad proteins, but not through p44/42MAPK proteins. Furthermore, we identified a negative feedback loop in which BMP-2 decreased endogenous FGF21 mRNA expression. In summary, this study demonstrates interactions between BMP-2 and FGF21 pathways exist in vitro, and that FGF21 enhances the osteogenic activity of BMP-2 by up-regulating the BMP-2-dependent Smad signaling pathway.

All-trans retinoic acid protects hepatocellular carcinoma cells against serum-starvation-induced cell death by upregulating collagen 8A2

As a therapeutic or chemopreventative agent for various cancers, all-trans retinoic acid (atRA) has been reported to inhibit growth, induce apoptosis or cause differentiation. It was found that atRA could protect hepatocellular carcinoma (HCC) cells against cell death induced by serum starvation. Furthermore, it was found that atRA could enhance cell adhesion, but had no effect on the cell cycle and apoptosis. Using an Illumina Human HT-12 v4 expression microarray, 207 upregulated and 173 downregulated genes were identified in HepG2 cells treated with atRA. The most upregulated genes are cytochrome P450 family 26 subfamily A polypeptide 1 (CYP26A1), histidine triad nucleotide binding protein 3 (HINT3), miR-1282 and cytochrome P450 family 26 subfamily B polypeptide 1 (CYP26B1), which showed more than fivefold greater expression. Using Gene Ontology analysis, the greatest significance was found in extracellular-matrix-related molecular functions and the cellular component in upregulated genes. The upregulation of collagen 8A2 (COL8A2) was further confirmed using quantitative RT-PCR and western blotting. Knockdown of COL8A2 blocked enhancement in the early stage of cell adhesion by atRA treatment. Re-expression of COL8A2 in COL8A2-knocked-down HCC cells reversed the effect of small interfering RNA-COL8A2. In addition, COL8A2 could increase HCC cell migration and invasion. Thus, COL8A2 was identified as the key protein involved in the enhancement of cell adhesion of atRA under serum-free conditions. In conclusion, atRA protects HCC cells against serum-starvation-induced cell death by enhancing cell adhesion, and COL8A2 plays an important role in HCC cell migration and invasion.

Collagen VIII influences epithelial phenotypic changes in experimental diabetic nephropathy

Epithelial-to-mesenchymal transition (EMT) is an important mechanism of renal tubulo-interstitial fibrosis in diabetic nephropathy (DN). Inducers of EMT, among others, are transforming growth factor-β(1) (TGF-β(1)) as well as extracellular collagens. In renal cells of diabetic mice and in kidneys of patients with DN, the expression of collagen VIII (gene: Col8α1/α2) is enhanced and characteristic features of DN in streptozotocin (STZ)-induced diabetic Col8α1/α2 knockout-(KO) mice are attenuated compared with diabetic wild-type mice. This study aimed to investigate whether collagen type VIII may influence the induction of EMT. DN was induced in wild-type and Col8α1/α2-KO mice using the established and widely accepted low-dose STZ model [treatment for 5 consecutive days (50 mg/kg)]. Healthy and diabetic mice were analyzed for changes in renal function and the expression of EMT-related genes and proteins. Renal morphology, fibrosis, and various EMT markers were studied in kidneys using immunohistological and molecular biological methods. Knockout of Col8α1/α2 attenuated albuminuria, extracellular matrix production, as well as fibrosis. Furthermore, the kidneys of diabetic Col8α1/α2-KO mice showed a marked reduction in interstitial myofibroblasts, and in tubular cells the inhibition of the expression of epithelial markers as well as the expression of typical mesenchymal markers was reduced. The present study demonstrates that in contrast to diabetic wild-type mice EMT-like changes were attenuated in diabetic Col8α1/α2-KO mice, which indicates that either collagen VIII may be one of the major inducers of EMT-like changes in kidneys of diabetic wild-type mice or/possibly the lack of Col8α1/α2 disrupts TGF-β(1)-induced EMT-like changes.

Differential response of arterial and venous endothelial cells to extracellular matrix is modulated by oxygen

Binding of endothelial cell (EC) integrins to extracellular-matrix (ECM) components is one of the key events to trigger intracellular signaling that will ultimately result in proper vascular development. Even within one tissue, the endothelial phenotype differs between arteries and veins. Here, we tested the hypothesis that anchorage dependent processes, such as proliferation, viability, survival and actin organization of venous (VEC) and arterial EC (AEC) differently depend on ECM proteins. Moreover,because of different oxygen tension in AEC and VEC, we tested oxygen as a co-modulator of ECM effects. Primary human placental VEC and AEC were grown in collagens I and IV, fibronectin, laminin, gelatin and uncoated plates and exposed to 12 and 21% oxygen. Our main findings revealed that VEC are more sensitive than AEC to changes in the ECM composition. Proliferation and survival of VEC, in contrast to AEC, were profoundly increased by the presence of collagen I and fibronectin when compared with gelatin or uncoated plates. These effects were reversed by inhibition of focal adhesion kinase (Fak) and modulated by oxygen. VEC were more susceptible to the oxygen dependent ECM effects than AEC. However, no differential ECM effect on actin organization was observed between the two cell types. These data provide first evidence that AEC and VEC from the same vascular loop respond differently to ECM and oxygen in a Fak-dependent manner.