Nephronectin is upregulated in acute and chronic hepatitis and aggravates liver injury by recruiting CD4 positive cells

Characterisation of a COPD-associated nephronectin (NPNT) functional splicing genetic variant in human lung tissue via long-read sequencing

BACKGROUND

Identification of COPD disease-causing genes is an important tool for understanding why COPD develops, who is at highest COPD risk and how new COPD treatments can be developed. Previous COPD genetic studies have identified a highly significant genetic association near NPNT (nephronectin), a gene involved in tissue repair, but the biological mechanisms underlying this association are unknown.

METHODS

Splicing quantitative trait locus (sQTL) analysis was performed to identify common genetic variants that alter RNA splicing in lung tissues. These lung sQTL signals were compared to COPD genetic association results near the NPNT gene using colocalisation analysis to determine whether genetic risk for COPD in this region may act through altered splicing. Long-read sequencing characterised COPD-associated splicing events at isoform-level resolution and in silico protein structural analysis identified likely functional effects of this alternative splicing.

RESULTS

An established COPD genetic risk variant, rs34712979-A, creates a cryptic splice acceptor site that causes four separate splicing changes in NPNT. The only one of these splicing changes that was associated with COPD phenotypes involved a cassette exon (exon 3). Long-read RNA sequencing demonstrated that the COPD risk allele causes a shift in isoform usage away from the dominant NPNT isoform B precursor, which excludes exon 3, to the isoform A precursor, which splices-in exon 3. AlphaFold protein structural analysis reveals that inclusion of this exon disrupts an epidermal growth factor-like functional domain in NPNT.

CONCLUSION

Genetic variants in the NPNT gene increase COPD risk by changing RNA splicing of NPNT in the lung.

Serum proteomic profiling of patients with compensated advanced chronic liver disease with and without clinically significant portal hypertension

INTRODUCTION

Portal hypertension (PH) drives the progression of liver cirrhosis to decompensation and death. Hepatic venous pressure gradient (HVPG) measurement is the standard of PH quantification, and HVPG≥10 mmHg defines clinically significant PH (CSPH). We performed proteomics-based serum profiling to search for a proteomic signature of CSPH in patients with compensated advanced chronic liver disease (cACLD).

MATERIALS AND METHODS

Consecutive patients with histologically confirmed cACLD and results of HVPG measurements were prospectively included. Serum samples were pooled according to the presence/absence of CSPH and analysed by liquid chromatography-mass spectrometry. Gene set enrichment analysis was performed, followed by comprehensive literature review for proteins identified with the most striking difference between the groups.

RESULTS

We included 48 patients (30 with, and 18 without CSPH). Protein CD44, involved in the inflammatory response, vascular endothelial growth factor C (VEGF-C) and lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), both involved in lymphangiogenesis were found solely in the CSPH group. Although identified in both groups, proteins involved in neutrophil extracellular traps (NET) formation, as well as tenascin C, autotaxin and nephronectin which mediate vascular contractility and lymphangiogenesis were more abundant in CSPH.

DISCUSSION AND CONCLUSION

We propose that altered inflammatory response, including NET formation, vascular contractility and formation of new lymph vessels are key steps in PH development. Proteins such as CD44, VEGF-C, LYVE-1, tenascin C, Plasminogen activator inhibitor 1, Nephronectin, Bactericidal permeability-increasing protein, Autotaxin, Myeloperoxidase and a disintegrin and metalloproteinase with thrombospondin motifs-like protein 4 might be considered for further validation as potential therapeutic targets and candidate biomarkers of CSPH in cACLD.

Proteome-wide Mendelian randomization implicates nephronectin as an actionable mediator of the effect of obesity on COVID-19 severity

Obesity is a major risk factor for Coronavirus disease (COVID-19) severity; however, the mechanisms underlying this relationship are not fully understood. As obesity influences the plasma proteome, we sought to identify circulating proteins mediating the effects of obesity on COVID-19 severity in humans. Here, we screened 4,907 plasma proteins to identify proteins influenced by body mass index using Mendelian randomization. This yielded 1,216 proteins, whose effect on COVID-19 severity was assessed, again using Mendelian randomization. We found that an s.d. increase in nephronectin (NPNT) was associated with increased odds of critically ill COVID-19 (OR = 1.71, P = 1.63 × 10-10). The effect was driven by an NPNT splice isoform. Mediation analyses supported NPNT as a mediator. In single-cell RNA-sequencing, NPNT was expressed in alveolar cells and fibroblasts of the lung in individuals who died of COVID-19. Finally, decreasing body fat mass and increasing fat-free mass were found to lower NPNT levels. These findings provide actionable insights into how obesity influences COVID-19 severity.

Endotoxin-induced acute lung injury in mice with postnatal deletion of nephronectin

Acute injury of the lung involves damage to the epithelium and its underlying extracellular matrix (ECM), the basement membrane (BM). How BMs contribute to injury resolution is poorly understood. Nephronectin (NPNT) is a high-affinity ligand for integrin α8β1 and, although first identified in the mouse kidney, is prominently expressed in the lung, where it localizes to BMs in the alveoli. To determine if NPNT plays a role in acute injury and inflammation of the lung, we developed a model for postnatal deletion of NPNT using mice with a floxed allele of Npnt in combination with a tamoxifen-inducible Cre recombinase expressed at the ROSA locus. Expression of NPNT was substantially reduced in lungs from tamoxifen-treated Cre+ animals. Cre+ mice and Cre- controls were given E. coli LPS by oropharyngeal aspiration to induce injury and inflammation. In Cre- lungs, although both Npnt and Itga8 (integrin α8) transcripts were downregulated at the peak of inflammation, NPNT protein was still detectable. While the onset of inflammation was similar for Cre+ and Cre-, NPNT-deficient lungs still had thickened alveolar septa and there were increased macrophages in the bronchoalveolar lavage fluid (BALF) in the resolution phase. BALF from Cre+ lungs was more chemotactic for bone marrow-derived macrophages than Cre- in in vitro experiments, but there were no differences in the elaboration of chemokines in vivo. We speculate that absence of NPNT in BMs of the alveoli impairs or delays inflammatory and injury resolution in this model, but further studies are needed to establish the precise role of NPNT in tissue repair.

Nephronectin-Integrin α8 signaling is required for proper migration of periocular neural crest cells during chick corneal development

During development, cells aggregate at tissue boundaries to form normal tissue architecture of organs. However, how cells are segregated into tissue precursors remains largely unknown. Cornea development is a perfect example of this process whereby neural crest cells aggregate in the periocular region prior to their migration and differentiation into corneal cells. Our recent RNA-seq analysis identified upregulation of nephronectin (Npnt) transcripts during early stages of corneal development where its function has not been investigated. We found that Npnt mRNA and protein are expressed by various ocular tissues, including the migratory periocular neural crest (pNC), which also express the integrin alpha 8 (Itgα8) receptor. Knockdown of either Npnt or Itgα8 attenuated cornea development, whereas overexpression of Npnt resulted in cornea thickening. Moreover, overexpression of Npnt variants lacking RGD-binding sites did not affect corneal thickness. Neither the knockdown nor augmentation of Npnt caused significant changes in cell proliferation, suggesting that Npnt directs pNC migration into the cornea. In vitro analyses showed that Npnt promotes pNC migration from explanted periocular mesenchyme, which requires Itgα8, focal adhesion kinase, and Rho kinase. Combined, these data suggest that Npnt augments cell migration into the presumptive cornea extracellular matrix by functioning as a substrate for Itgα8-positive pNC cells.

Cadmium-Associated Molecular Signatures in Cancer Cell Models

The exposure of cancer cells to cadmium and its compounds is often associated with the development of more malignant phenotypes, thereby contributing to the acceleration of tumor progression. It is known that cadmium is a transcriptional regulator that induces molecular reprogramming, and therefore the study of differentially expressed genes has enabled the identification and classification of molecular signatures inherent in human neoplastic cells upon cadmium exposure as useful biomarkers that are potentially transferable to clinical research. This review recapitulates selected studies that report the detection of cadmium-associated signatures in breast, gastric, colon, liver, lung, and nasopharyngeal tumor cell models, as specifically demonstrated by individual gene or whole genome expression profiling. Where available, the molecular, biochemical, and/or physiological aspects associated with the targeted gene activation or silencing in the discussed cell models are also outlined.

Nephronectin as a Matrix Effector in Cancer

Simple Summary

The extracellular matrix provides an important scaffold for cells and tissues of multicellular organisms. The scaffold not only provides a secure anchorage point, but also functions as a reservoir for signalling molecules, sequestered and released when necessary. A dysregulated extracellular matrix may therefore modulate cellular behaviour, as seen during cancer progression. The extracellular matrix protein nephronectin was discovered two decades ago and found to regulate important embryonic developmental processes. Loss of either nephronectin or its receptor, integrin α8β1, leads to underdeveloped kidneys. Recent findings show that nephronectin is also dysregulated in breast cancer and plays a role in promoting metastasis. To enable therapeutic intervention, it is important to fully understand the role of nephronectin and its receptors in cancer progression. In this review, we summarise the literature on nephronectin, analyse the structure and domain-related functions of nephronectin and link these functions to potential roles in cancer progression.

Abstract

The extracellular matrix protein nephronectin plays an important regulatory role during embryonic development, controlling renal organogenesis through integrin α8β1 association. Nephronectin has three main domains: five N-terminal epidermal growth factor-like domains, a linker region harbouring two integrin-binding motifs (RGD and LFEIFEIER), and a C-terminal MAM domain. In this review, we look into the domain-related functions of nephronectin, and tissue distribution and expression. During the last two decades it has become evident that nephronectin also plays a role during cancer progression and in particular metastasis. Nephronectin is overexpressed in both human and mouse breast cancer compared to normal breast tissue where the protein is absent. Cancer cells expressing elevated levels of nephronectin acquire increased ability to colonise distant organs. In particular, the enhancer-motif (LFEIFEIER) which is specific to the integrin α8β1 association induces viability via p38 MAPK and plays a role in colonization. Integrins have long been desired as therapeutic targets, where low efficiency and receptor redundancy have been major issues. Based on the summarised publications, the enhancer-motif of nephronectin could present a novel therapeutic target.

BRG1 Mediates Nephronectin Activation in Hepatocytes to Promote T Lymphocyte Infiltration in ConA-Induced Hepatitis

Fulminant hepatitis (FH) is a major cause of acute liver failure. Concanavalin A (ConA) belongs to the lectin family and is frequently used as an inducer of FH in animal models. ConA induced FH is characterized by massive accumulation of T lymphocytes in the liver. A host of chemoattractive substances are known to promote T cell homing to the liver during acute hepatitis. Here we investigated the involvement of Brahma-related gene 1 (BRG1), a chromatin remodeling protein, in FH. BRG1-flox mice were crossed to Alb-Cre mice to generate hepatocyte conditional BRG1 knockout (LKO) mice. The mice were peritoneally injected with a single dose of ConA to induce FH. BRG1 deficiency mitigated ConA-induced FH in mice. Consistently, there were fewer T lymphocyte infiltrates in the LKO livers compared to the wild type (WT) livers paralleling downregulation of T cell specific cytokines. Further analysis revealed that BRG1 deficiency repressed the expression of several chemokines critical for T cell homing including nephronectin (Npnt). BRG1 knockdown blocked the induction of Npnt in hepatocytes and attenuated T lymphocyte migration in vitro, which was reversed by the addition of recombinant nephronectin. Mechanistically, BRG1 interacted with β-catenin to directly bind to the Npnt promoter and activate Npnt transcription. Importantly, a positive correlation between infiltration of CD3⁺ T lymphocyes and nephronectin expression was detected in human acute hepatitis biopsy specimens. In conclusion, our data identify a novel role for BRG1 as a promoter of T lymphocyte trafficking by activating Npnt transcription in hepatocytes. Targeting the BRG1-Npnt axis may yield novel therapeutic solutions for FH.

Antibodies against nephronectin ameliorate anti-type II collagen-induced arthritis in mice

The extracellular matrix protein nephronectin (Npnt) is known to be critical for kidney development, but its function in inflammatory diseases is unknown. Here, we developed a new enzyme‐linked immunosorbent assay system to detect Npnt in various autoimmune diseases, which revealed that plasma Npnt levels are increased in various mouse autoimmune models. We also report that antibodies against the α8β1 integrin‐binding region of Npnt protect mice from anti‐type II collagen‐induced arthritis, suggesting that Npnt may be a potential therapeutic target molecule for the prevention of autoimmune arthritis.

Multiomics analysis profile acute liver injury module clusters to compare the therapeutic efficacy of bifendate and muaddil sapra

The pathogenesis of acute liver injury has been plagued by biologists and physicians. We know little about its therapeutic mechanism. Therefore, this study explored the mechanism of bifendate and muaddil sapra in the treatment of acute liver injury. Firstly, co-expression and cluster analysis of disease-related genes were carried out, and the Go function and KEGG pathway of modules and related genes were identified. Secondly, pivot analysis of modules can identify key regulators. On the other hand, based on the acute liver injury induced by CCl4, we use the combined analysis of proteomics and transcriptome to find therapeutic targets and related mechanisms of drugs. A total of 21 dysfunction modules were obtained, which were significantly involved in immune system, hepatitis and other related functions and pathways. Transcriptome analysis showed 117 targets for bifendate treatment, while 119 for muaddil sapra. Through exploring the mechanism, we found that the two drugs could modulate the module genes. Moreover, bifendate regulate the dysfunction module through ncRNA (SNORD43 and RNU11). Muaddil sapra can mediate dysfunction modules not only by regulating ncRNA (PRIM2 and PIP5K1B), but also by regulating TF (STAT1 and IRF8), thus having a wider therapeutic potential. On the other hand, proteome analysis showed that bifendate mainly regulated Rac2, Fermt3 and Plg, while muaddil sapra mainly regulated Sqle and Stat1. In addition, muaddil sapra regulates less metabolic related proteins to make them more effective. Overall, this study not only provides basic theory for further study of the complex pathogenesis of acute liver injury, but also provides valuable reference for clinical use of bifendate and muaddil sapra in the treatment of acute liver injury.

Isolation of a unique hepatic stellate cell population expressing integrin α8 from embryonic mouse livers

BACKGROUND

Hepatic stellate cells (HSCs) play an important role in liver fibrogenesis. However, little is known about their phenotype and role in liver development. The aim of this study is to identify specific markers for embryonic HSCs.

RESULTS

Using antibodies against ALCAM and PDPN, we separated mesothelial cells (MCs) and HSCs from developing livers and identified integrin α8 (ITGA8) as a marker for embryonic desmin+ HSCs that are preferentially localized near the developing liver surface and α-smooth muscle actin+ perivascular mesenchymal cells around the vein. A cell lineage-tracing study revealed that upon differentiation, MC-derived HSCs or perivascular mesenchymal cells express ITGA8 during liver development. Using anti-ITGA8 antibodies, we succeeded in isolating MC-derived HSCs and perivascular mesenchymal cells from embryonic livers. In direct co-culture, ITGA8+ mesenchymal cells promoted the expression of hepatocyte and cholangiocyte markers in hepatoblasts. In the normal adult liver, expression of ITGA8 was restricted to portal fibroblasts in the portal triad. Upon liver injury, myofibroblasts increased the expression of ITGA8.

CONCLUSIONS

ITGA8 is a specific cell surface marker of MC-derived HSCs and perivascular mesenchymal cells in the developing liver. Our data suggest that ITGA8+ mesenchymal cells maintain the phenotype of hepatoblast in liver development. Developmental Dynamics 247:867-881, 2018. © 2018 Wiley Periodicals, Inc.

Physiological and Pathological Roles in Human Adrenal of the Glomeruli-Defining Matrix Protein NPNT (Nephronectin)

Primary aldosteronism is a common cause of hypertension, which becomes refractory if undiagnosed, but potentially curable when caused by an aldosterone-producing adenoma (APA). The discovery of somatic mutations and differences in clinical presentations led to recognition of small but common zona glomerulosa (ZG)-like adenomas, distinct from classical large zona fasciculata-like adenomas. The inverse correlation between APA size and aldosterone synthase expression prompted us to undertake a systematic study of genotype-phenotype relationships. After a microarray comparing tumor subtypes, in which NPNT (nephronectin) was the most highly (>12-fold) upregulated gene in ZG-like APAs, we aimed to determine its role in physiological and pathological aldosterone production. NPNT was identified by immunohistochemistry as a secreted matrix protein expressed exclusively around aldosterone-producing glomeruli in normal adrenal ZG and in aldosterone-dense ZG-like APAs; the highest expression was in ZG-like APAs with gain-of-function CTNNB1 mutations, whose removal cured hypertension in our patients. NPNT was absent from normal zona fasciculata, zona fasciculata-like APAs, and ZG adjacent to an APA. NPNT production was regulated by canonical Wnt pathway, and NPNT overexpression or silencing increased or reduced aldosterone, respectively. NPNT was proadhesive in primary adrenal and APA cells but antiadhesive and antiapoptotic in immortalized adrenocortical cells. The discovery of NPNT in the adrenal helped recognition of a common subtype of APAs and a pathway by which Wnt regulates aldosterone production. We propose that this arises through NPNT's binding to cell-surface integrins, stimulating cell-cell contact within glomeruli, which define ZG. Therefore, NPNT or its cognate integrin could present a novel therapeutic target.

Expression and localization of sterile alpha motif domain containing 5 is associated with cell type and malignancy of biliary tree

Cholangiocarcinoma (CC) is a type of relatively rare neoplasm in adenocarcinoma. The characteristics of CCs as well as biliary epithelial cells are heterogeneous at the different portion of the biliary tree. There are two candidate stem/progenitor cells of the biliary tree, i.e., biliary tree stem/progenitor cell (BTSC) at the peribiliary gland (PBG) of large bile ducts and liver stem/progenitor cell (LPC) at the canals of Hering of peripheral small bile duct. Although previous reports suggest that intrahepatic CC (ICC) can arise from such stem/progenitor cells, the characteristic difference between BTSC and LPC in pathological process needs further investigation, and the etiology of CC remains poorly understood. Here we show that Sterile alpha motif domain containing 5 (SAMD5) is exclusively expressed in PBGs of large bile ducts in normal mice. Using a mouse model of cholestatic liver disease, we demonstrated that SAMD5 expression was upregulated in the large bile duct at the hepatic hilum, the extrahepatic bile duct and PBGs, but not in proliferating intrahepatic ductules, suggesting that SAMD5 is expressed in BTSC but not LPC. Intriguingly, human ICCs and extrahepatic CCs exhibited striking nuclear localization of SAMD5 while the normal hilar large bile duct displayed slight-to-moderate expression in cytoplasm. In vitro experiments using siRNA for SAMD5 revealed that SAMD5 expression was associated with the cell cycle regulation of CC cell lines. Conclusion: SAMD5 is a novel marker for PBG but not LPC in mice. In humans, the expression and location of SAMD5 could become a promising diagnostic marker for the cell type as well as malignancy of bile ducts and CCs.

Long noncoding RNA repertoire in chicken liver and adipose tissue

BACKGROUND

Improving functional annotation of the chicken genome is a key challenge in bridging the gap between genotype and phenotype. Among all transcribed regions, long noncoding RNAs (lncRNAs) are a major component of the transcriptome and its regulation, and whole-transcriptome sequencing (RNA-Seq) has greatly improved their identification and characterization. We performed an extensive profiling of the lncRNA transcriptome in the chicken liver and adipose tissue by RNA-Seq. We focused on these two tissues because of their importance in various economical traits for which energy storage and mobilization play key roles and also because of their high cell homogeneity. To predict lncRNAs, we used a recently developed tool called FEELnc, which also classifies them with respect to their distance and strand orientation to the closest protein-coding genes. Moreover, to confidently identify the genes/transcripts expressed in each tissue (a complex task for weakly expressed molecules such as lncRNAs), we probed a particularly large number of biological replicates (16 per tissue) compared to common multi-tissue studies with a larger set of tissues but less sampling.

RESULTS

We predicted 2193 lncRNA genes, among which 1670 were robustly expressed across replicates in the liver and/or adipose tissue and which were classified into 1493 intergenic and 177 intragenic lncRNAs located between and within protein-coding genes, respectively. We observed similar structural features between chickens and mammals, with strong synteny conservation but without sequence conservation. As previously reported, we confirm that lncRNAs have a lower and more tissue-specific expression than mRNAs. Finally, we showed that adjacent lncRNA-mRNA genes in divergent orientation have a higher co-expression level when separated by less than 1 kb compared to more distant divergent pairs. Among these, we highlighted for the first time a novel lncRNA candidate involved in lipid metabolism, lnc_DHCR24, which is highly correlated with the DHCR24 gene that encodes a key enzyme of cholesterol biosynthesis.

CONCLUSIONS

We provide a comprehensive lncRNA repertoire in the chicken liver and adipose tissue, which shows interesting patterns of co-expression between mRNAs and lncRNAs. It contributes to improving the structural and functional annotation of the chicken genome and provides a basis for further studies on energy storage and mobilization traits in the chicken.

NK cells activated by Interleukin-4 in cooperation with Interleukin-15 exhibit distinctive characteristics

Natural killer (NK) cells are known to be activated by Th1-type cytokines, such as IL-2, -12, or -18, and they secrete a large amount of IFN-γ that accelerates Th1-type responses. However, the roles of NK cells in Th2-type responses have remained unclear. Because IL-4 acts as an initiator of Th2-type responses, we examined the characteristics of NK cells in mice overexpressing IL-4. In this study, we report that IL-4 overexpression induces distinctive characteristics of NK cells (B220(high)/CD11b(low)/IL-18Rα(low)), which are different from mature conventional NK (cNK) cells (B220(low)/CD11b(high)/IL-18Rα(high)). IL-4 overexpression induces proliferation of tissue-resident macrophages, which contributes to NK cell proliferation via production of IL-15. These IL-4-induced NK cells (IL4-NK cells) produce higher levels of IFN-γ, IL-10, and GM-CSF, and exhibit high cytotoxicity compared with cNK cells. Furthermore, incubation of cNK cells with IL-15 and IL-4 alters their phenotype to that similar to IL4-NK cells. Finally, parasitic infection, which typically causes strong Th2-type responses, induces the development of NK cells with characteristics similar to IL4-NK cells. These IL4-NK-like cells do not develop in IL-4Rα KO mice by parasitic infection. Collectively, these results suggest a novel role of IL-4 in immune responses through the induction of the unique NK cells.

Gene expression and pathway analysis of human hepatocellular carcinoma cells treated with cadmium

Cadmium (Cd) is a toxic and carcinogenic metal naturally occurring in the Earth's crust. A common route of human exposure is via diet and cadmium accumulates in the liver. The effects of Cd exposure on gene expression in human hepatocellular carcinoma (HepG2) cells were examined in this study. HepG2 cells were acutely-treated with 0.1, 0.5, or 1.0 μM Cd for 24h; or chronically-treated with 0.01, 0.05, or 0.1 μM Cd for three weeks and gene expression analysis was performed using Affymetrix GeneChip® Human Gene 1.0 ST Arrays. Acute and chronic exposures significantly altered the expression of 333 and 181 genes, respectively. The genes most upregulated by acute exposure included several metallothioneins. Downregulated genes included the monooxygenase CYP3A7, involved in drug and lipid metabolism. In contrast, CYP3A7 was upregulated by chronic Cd exposure, as was DNAJB9, an anti-apoptotic J protein. Genes downregulated following chronic exposure included the transcriptional regulator early growth response protein 1. Ingenuity Pathway Analysis revealed that the top networks altered by acute exposure were lipid metabolism, small molecule biosynthesis, cell morphology, organization, and development; while top networks altered by chronic exposure were organ morphology, cell cycle, cell signaling, and renal and urological diseases/cancer. Many of the dysregulated genes play important roles in cellular growth, proliferation, and apoptosis, and may be involved in carcinogenesis. In addition to gene expression changes, HepG2 cells treated with cadmium for 24h indicated a reduction in global levels of histone methylation and acetylation that persisted 72 h post-treatment.

Expression of nephronectin is inhibited by oncostatin M via both JAK/STAT and MAPK pathways

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Oncostatin M regulates nephronectin (Npnt) gene expression in a dose- and time dependent manner.

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Nephronectin gene expression is regulated by JAK/STAT and MAPK pathways.

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Down-regulation of Npnt influences inhibition of osteoblast differentiation by oncostatin M.

Nephronectin (Npnt), also called POEM, is an extracellular matrix protein considered to play critical roles as an adhesion molecule in the development and functions of various tissues, such as the kidneys, liver, and bones. In the present study, we examined the molecular mechanism of Npnt gene expression and found that oncostatin M (OSM) strongly inhibited Npnt mRNA expression in MC3T3-E1 cells from a mouse osteoblastic cell line. OSM also induced a decrease in Npnt expression in both time- and dose-dependent manners via both the JAK/STAT and MAPK pathways. In addition, OSM-induced inhibition of osteoblast differentiation was recovered by over-expression of Npnt. These results suggest that OSM inhibits Npnt expression via the JAK/STAT and MAPK pathways, while down-regulation of Npnt by OSM influences inhibition of osteoblast differentiation.

Mature resting Ly6C(high) natural killer cells can be reactivated by IL-15

Mature NK cells are heterogeneous as to their expression levels of cell surface molecules. However, the functional differences and physiological roles of each NK-cell subset are not fully understood. In this study, we report that based on the Ly6C expression levels, mature C57BL/6 murine NK cells can be subdivided into Ly6C(low) and Ly6C(high) subsets. Ly6C(high) NK cells are in an inert state as evidenced by the production of lower levels of IFN-γ and granzyme B, and they exhibit poorer proliferative potential than Ly6C(low) NK cells. In addition, adoptive transfer experiments revealed that Ly6C(high) NK cells are derived from Ly6C(low) NK cells in the steady state. These results strongly suggest that Ly6C(high) NK cells are resting cells in the steady state. However, in vitro, Ly6C(high) NK cells become Ly6C(low) NK cells with strong effector functions upon stimulation with IL-15. Moreover, Ly6C(high) NK cells also revert to Ly6C(low) NK cells in vivo upon injection of the IL-15 inducers polyI:C and CpG. Taken together, these results demonstrate the plasticity of mature NK cells and suggest that Ly6C(high) NK cells are a reservoir of potential NK cells that allow effective and strong response to infections.

Semaphorin 3E secreted by damaged hepatocytes regulates the sinusoidal regeneration and liver fibrosis during liver regeneration

The liver has a remarkable capacity to regenerate after injury. Although the regulatory mechanisms of hepatocytic regeneration have been a subject of intense study, the dynamism of the sinusoids, specialized blood vessels in the liver, remains largely unknown. Transient activation of hepatic stellate cells and hepatic sinusoidal endothelial cells, which constitute the sinusoids, contributes to liver regeneration during acute injury, whereas their sustained activation causes liver fibrosis during chronic injury. We focused on understanding the association between damaged hepatocytes and sinusoidal regeneration or liver fibrogenesis using a carbon tetrachloride-induced liver injury mouse model. Damaged hepatocytes rapidly expressed semaphorin 3E (Sema3e), which induced contraction of sinusoidal endothelial cells and thereby contributed to activating hepatic stellate cells for wound healing. In addition, ectopic and consecutive expression of Sema3e in hepatocytes by the hydrodynamic tail-vein injection method resulted in disorganized regeneration of sinusoids and sustained activation of hepatic stellate cells. In contrast, liver fibrosis ameliorated in Sema3e-knockout mice compared with wild-type mice in a chronic liver injury model. Our results indicate that Sema3e, secreted by damaged hepatocytes, affects sinusoidal regeneration in a paracrine manner during liver regeneration, suggesting that Sema3e is a novel therapeutic target in liver fibrogenesis.

Nephronectin expression in glomeruli of renal biopsy specimens from various kidney diseases: nephronectin is expressed in the mesangial matrix expansion of diabetic nephropathy

BACKGROUND

In a previous proteomic study, we detected increased expression of nephronectin in the glomeruli from patients with diabetic nephropathy (DN). The aim of the present study was to clarify the usefulness of determining glomerular expression of nephronectin in kidney disease.

METHODS

We performed immunohistochemical staining for nephronectin in renal biopsy specimens from patients with a variety of kidney diseases (n = 190). The percentage of nephronectin-positive areas in the glomeruli was analyzed using an image analyzer.

RESULTS

Nephronectin immunoreactivity was clearly, strongly positive in the mesangial expansion and nodular lesions of DN (n = 18), whereas nephronectin immunoreactivity was negative in IgA glomerulonephritis, membranoproliferative glomerulonephritis, lupus nephritis, membranous glomerulonephritis, minor glomerular abnormalities, crescentic glomerulonephritis, and other kidney diseases, such as amyloidosis and light chain deposition disease. Nephronectin was stained weakly in sclerotic lesions, such as focal segmental glomerulosclerosis and hypertensive nephropathy. The percentage of nephronectin-positive areas in the glomeruli from DN patients [15.1 ± 4.7% (n = 18)] was significantly higher than that for other kidney diseases [5.5 ± 3.6% (n = 172)] (p < 0.001). In multiple regression analyses, fasting plasma glucose and hemoglobin A1c were significantly associated with the increase in the percentage of nephronectin-positive areas in the glomeruli (β = 0.23, p < 0.001 and β = 0.16, p = 0.045, respectively).

CONCLUSIONS

The expression of nephronectin was sufficient to discriminate DN from other kidney diseases with mesangial matrix expansion and nodular lesions. We consider that nephronectin staining could be helpful in the diagnosis of DN.