Renoprotective effects of laxative linaclotide: Inhibition of acute kidney injury and fibrosis in a rat model of renal ischemia-reperfusion.

Ischemia-reperfusion (I/R) leads to tissue damage in transplanted kidneys, resulting in acute kidney injury (AKI) and chronic graft dysfunction, which critically compromises transplant outcomes, such as graft loss. Linaclotide, a guanylate cyclase C agonist clinically approved as a laxative, has recently been identified to exhibit renoprotective effects in a chronic kidney disease (CKD) model. This study evaluates the therapeutic effects of linaclotide on AKI triggered by I/R in a rat model with an initial comparison with other laxatives. Here, we show that linaclotide administration resulted in substantial reduction in serum creatinine levels, reflective of enhanced renal function. Histological examination revealed diminished tubular damage, and Sirius Red staining confirmed less collagen deposition, collectively indicating preserved structural integrity and mitigation of fibrosis. Further analysis demonstrated lowered expression of TGF-ß and associated fibrotic markers, α-SMA, MMP2, and TIMP1, implicating the downregulation of the fibrogenic TGF-ß pathway by linaclotide. Furthermore, one day after I/R insult, linaclotide profoundly diminished macrophage infiltration and suppressed critical pro-inflammatory cytokines such as TNF, IL-1ß, and IL-6, signifying its potential to disrupt initial inflammatory mechanisms integral to AKI pathology. These findings suggest that linaclotide, with its established safety profile, could extend its benefits beyond gastrointestinal issues and potentially serve as a therapeutic intervention for organ transplantation. Additionally, it could provide immediate and practical insights into selecting laxatives for managing patients with AKI or CKD, regardless of the cause, and for those receiving dialysis or transplant therapy.

Caveolin-1 forms a complex with P2X7 receptor and tunes P2X7-mediated ATP signaling in mouse bone marrow-derived macrophages.

The ionotropic purinergic P2X7 receptor responds to extracellular ATP and can trigger proinflammatory immune signaling in macrophages. Caveolin-1 (Cav-1) is known to modulate functions of macrophages and innate immunity. However, it is unknown how Cav-1 modulates P2X7 receptor activity in macrophages. We herein examined P2X7 receptor activity and macrophage functions using bone marrow-derived macrophages (BMDMs) from wild-type (WT) and Cav-1 knockout (KO) mice. ATP (1 mM) application caused biphasic increase in cytosolic [Ca2+] and sustained decrease in cytosolic [K+]. A specific P2X7 receptor blocker, A-740003, inhibited the maintained cytosolic [Ca2+] increase and cytosolic [K+] decrease. Total internal reflection fluorescent imaging and proximity ligation assays revealed a novel molecular complex formation between P2X7 receptors and Cav-1 in WT BMDMs that were stimulated with lipopolysaccharides. This molecular coupling was increased by ATP application. Specifically, the ATP-induced Ca2+ influx and K+ efflux through P2X7 receptors were increased in Cav-1 KO BMDMs, even though the total and surface protein levels of P2X7 receptors in WT and Cav-1 KO BMDMs were unchanged. Cell-impermeable dye (TO-PRO3) uptake analysis revealed that macropore formation of P2X7 receptors was enhanced in Cav-1 KO BMDMs. Cav-1 KO BMDMs increased ATP-induced IL-1ß secretion, reactive oxygen species production, Gasdermin D (GSDMD) cleavage, and lactate dehydrogenase release indicating pyroptosis. A-740003 completely prevented ATP-induced pyroptosis. In combination, these datasets show that Cav-1 has a negative effect on P2X7 receptor activity in BMDMs and that Cav-1 in macrophages may contribute to finely tuned immune responses by preventing excessive IL-1ß secretion and pyroptosis.NEW & NOTEWORTHY In bone marrow-derived macrophages, Cav-1 suppresses the macropore formation of P2X7 receptors through their direct or indirect interactions, resulting in reduced membrane permeability of cations (Ca2+ and K+) and large cell-impermeable dye (TO-PRO3) induced by ATP. Cav-1 also inhibits ATP-induced IL-1ß secretion, ROS production, GSDMD cleavage, and pyroptosis. Cav-1 contributes to the maintenance of proper immune responses by finely tuning IL-1ß secretion and cell death in macrophages.

Dantrolene, a stabilizer of the ryanodine receptor, prevents collagen-induced arthritis.

Dantrolene inhibits Ca2+ leakage from destabilized ryanodine receptors and therefore may serve as a therapeutic agent against endoplasmic reticulum stress-associated diseases. However, its effectiveness in treating autoimmune diseases remains unclear. Here, we investigated the effect of dantrolene on collagen-induced arthritis (CIA) in mice. Oral administration of dantrolene resulted in significantly lower arthritic scores in both male and female CIA mice than in the control mice. Micro-computed tomographic and histological analyses showed that dantrolene suppressed bone and chondral destruction. The serum levels of anti-type II collagen (CII) IgG were positively correlated with the arthritic scores (r = 0.704, p < 0.01). In addition, the serum levels of anti-CII IgG were significantly lower in the dantrolene group than in the control group (p < 0.05). These results demonstrate that oral administration of dantrolene to CIA mice inhibits the production of serum anti-CII IgG and consequently prevents arthritis. Therefore, dantrolene may be a potential anti-rheumatic drug.

Calcium/calmodulin-dependent regulation of Rac GTPases and Akt in histamine-induced chemotaxis of mast cells.

Histamine induces chemotaxis of mast cells through the histamine H4 receptor. This involves the activation of small GTPases, Rac1 and Rac2, downstream of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K). Activation of the H4 receptor also results in phospholipase C (PLC)-mediated calcium mobilization; however, it is unclear whether the PLC­calcium pathway interacts with the PI3K-Rac pathway. Here, we demonstrated that calcium mobilization regulates the PI3K-dependent activation of Rac GTPases through calmodulin. A PLC inhibitor (U73122) and an intracellular calcium chelator (BAPTA-AM) suppressed the histamine-induced activation of Rac, whereas the calcium ionophore ionomycin increased the active Rac GTPases, suggesting that intracellular calcium regulates the activation of Rac. The calmodulin antagonist (W-7) inhibited the histamine-induced activation of Rac and migration of mast cells, indicating that calmodulin mediates the effect of calcium. Inhibition of calcium/calmodulin signaling suppressed histamine-induced phosphorylation of Akt. The Akt inhibitor MK-2206 attenuated histamine-induced migration of mast cells. However, it did not suppress the activation of Rac GTPases. These results suggest that Rac GTPases and Akt play independent roles in the histamine-induced chemotaxis of mast cells. Our findings enable further elucidation of the molecular mechanism of histamine-induced chemotaxis of mast cells and help identify therapeutic targets for allergic and inflammatory conditions involving mast cell accumulation.

Gene expression profiles of liver cancer cell lines reveal two hepatocyte-like and fibroblast-like clusters.

Cancer cell lines are widely used in basic research to study cancer development, growth, invasion, or metastasis. They are also used for the development and screening of anticancer drugs. However, there are no clear criteria for choosing the most suitable cell lines among the wide variety of cancer cell lines commercially available for research, and the choice is often based on previously published reports. Here, we investigated the characteristics of liver cancer cell lines by analyzing the gene expression data available in the Cancer Cell Line Encyclopedia. Unsupervised clustering analysis of 28 liver cancer cell lines yielded two main clusters. One cluster showed a gene expression pattern similar to that of hepatocytes, and the other showed a pattern similar to that of fibroblasts. Analysis of hepatocellular carcinoma gene expression profiles available in The Cancer Genome Atlas showed that the gene expression patterns in most hepatoma tissues were similar to those in the hepatocyte-like cluster. With respect to liver cancer research, our findings may be useful for selecting an appropriate cell line for a specific study objective. Furthermore, our approach of utilizing a public database for comparing the properties of cell lines could be an attractive cell line selection strategy that can be applied to other fields of research.

Cell Cycle Perturbation Induces Collagen Production in Fibroblasts.

Myocardial infarction (MI) occurs when the heart muscle is severely damaged due to a decrease in blood flow from the coronary arteries. During recovery from an MI, cardiac fibroblasts become activated and produce extracellular matrices, contributing to the wound healing process in the damaged heart. Inappropriate activation of the fibroblasts leads to excessive fibrosis in the heart. However, the molecular pathways by which cardiac fibroblasts are activated have not yet been fully elucidated.Here we show that serum deprivation, which recapitulates the cellular microenvironment of the MI area, strikingly induces collagen production in C3H/10T1/2 cells. Based on transcriptomic and pharmacological studies, we found that cell cycle perturbation is directly linked to collagen production in fibroblasts. Importantly, collagen synthesis is increased independently of the transcriptional levels of type I collagen genes. These results reveal a novel mode of fibroblast activation in the ischemic area, which will allow us to gain insights into the molecular mechanisms underlying cardiac fibrosis and establish a basis for anti-fibrotic therapy.

Macrophage hypoxia signaling regulates cardiac fibrosis via Oncostatin M.

The fibrogenic response in tissue-resident fibroblasts is determined by the balance between activation and repression signals from the tissue microenvironment. While the molecular pathways by which transforming growth factor-1 (TGF-ß1) activates pro-fibrogenic mechanisms have been extensively studied and are recognized critical during fibrosis development, the factors regulating TGF-ß1 signaling are poorly understood. Here we show that macrophage hypoxia signaling suppresses excessive fibrosis in a heart via oncostatin-m (OSM) secretion. During cardiac remodeling, Ly6Chi monocytes/macrophages accumulate in hypoxic areas through a hypoxia-inducible factor (HIF)-1α dependent manner and suppresses cardiac fibroblast activation. As an underlying molecular mechanism, we identify OSM, part of the interleukin 6 cytokine family, as a HIF-1α target gene, which directly inhibits the TGF-ß1 mediated activation of cardiac fibroblasts through extracellular signal-regulated kinase 1/2-dependent phosphorylation of the SMAD linker region. These results demonstrate that macrophage hypoxia signaling regulates fibroblast activation through OSM secretion in vivo.

Necrostatin-7 suppresses RANK-NFATc1 signaling and attenuates macrophage to osteoclast differentiation.

Osteoclasts play a crucial role in osteolytic bone diseases, such as osteoporosis, rheumatoid arthritis, periodontitis, Paget's disease of bone and bone metastatic tumors. Therefore, controlling osteoclast differentiation and function has been considered a promising therapeutic strategy. Here, we show that necrostatin (Nec)-7, an inhibitor of programmed necrosis, strongly suppressed receptor activator of nuclear factor (NF)-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption, without compromising macrophage colony-stimulating factor (M-CSF)-supported survival and growth of osteoclast precursor cells. Accordingly, Nec-7 significantly decreased the levels of RANKL-induced osteoclastogenic marker genes, such as cathepsin K. Mechanistically, Nec-7 neither affected MAPK nor NF-κB activation; however, it strongly inhibited the RANKL receptor (RANK) to nuclear factor of activated T cells c1 (NFATc1) signaling. Lentiviral expression of RANK in bone marrow-derived macrophages significantly restored osteoclastogenesis and NFATc1 amplification in Nec-7-treated cells. In this study, we revealed that Nec-7-sensitive pathways are crucially involved in osteoclast formation and function. Investigation of the molecular mechanism(s) through which Nec-7 inhibits RANK-NFATc1 signaling axis may lead to the development of new therapeutic strategies for bone disease.

Gallbladder-derived surfactant protein D regulates gut commensal bacteria for maintaining intestinal homeostasis.

The commensal microbiota within the gastrointestinal tract is essential in maintaining homeostasis. Indeed, dysregulation in the repertoire of microbiota can result in the development of intestinal immune-inflammatory diseases. Further, this immune regulation by gut microbiota is important systemically, impacting health and disease of organ systems beyond the local environment of the gut. What has not been explored is how distant organs might in turn shape the microbiota via microbe-targeted molecules. Here, we provide evidence that surfactant protein D (SP-D) synthesized in the gallbladder and delivered into intestinal lumen binds selectively to species of gut commensal bacteria. SP-D-deficient mice manifest intestinal dysbiosis and show a susceptibility to dextran sulfate sodium-induced colitis. Further, fecal transfer from SP-D-deficient mice to wild-type, germ-free mice conveyed colitis susceptibility. Interestingly, colitis caused a notable increase in Sftpd gene expression in the gallbladder, but not in the lung, via the activity of glucocorticoids produced in the liver. These findings describe a unique mechanism of interorgan regulation of intestinal immune homeostasis by SP-D with potential clinical implications such as cholecystectomy.

Pancreatic Stellate Cells Have Distinct Characteristics From Hepatic Stellate Cells and Are Not the Unique Origin of Collagen-Producing Cells in the Pancreas.

OBJECTIVES: The origin of collagen-producing myofibroblasts in pancreatic fibrosis is still controversial. Pancreatic stellate cells (PSCs), which have been recognized as the pancreatic counterparts of hepatic stellate cells (HSCs), are thought to play an important role in the development of pancreatic fibrosis. However, sources of myofibroblasts other than PSCs may exist because extensive studies of liver fibrosis have uncovered myofibroblasts that did not originate from HSCs. This study aimed to characterize myofibroblasts in an experimental pancreatic fibrosis model in mice. METHODS: We used transgenic mice expressing green fluorescent protein via the collagen type I α1 promoter and induced pancreatic fibrosis with repetitive injections of cerulein. RESULTS: Collagen-producing cells that are negative for glial fibrillary acidic protein (ie, not derived from PSCs) exist in the pancreas. Pancreatic stellate cells had different characteristics from those of HSCs in a very small possession of vitamin A using mass spectrometry and a low expression of lecithin retinol acyltransferase. The microstructure of PSCs was entirely different from that of HSCs using flow cytometry and electron microscopy. CONCLUSIONS: Our study showed that characteristics of PSCs are different from those of HSCs, and myofibroblasts in the pancreas might be derived not only from PSCs but also from other fibrogenic cells.

Actin-binding protein coronin 1A controls osteoclastic bone resorption by regulating lysosomal secretion of cathepsin K.

Osteoclasts degrade bone matrix proteins via the secretion of lysosomal enzymes. However, the precise mechanisms by which lysosomal components are transported and fused to the bone-apposed plasma membrane, termed ruffled border membrane, remain elusive. Here, we identified coronin 1A as a negative regulator of exocytotic release of cathepsin K, one of the most important bone-degrading enzymes in osteoclasts. The modulation of coronin 1A expression did not alter osteoclast differentiation and extracellular acidification, but strongly affected the secretion of cathepsin K and osteoclast bone-resorption activity, suggesting the coronin 1A-mediated regulation of lysosomal trafficking and protease exocytosis. Further analyses suggested that coronin 1A prevented the lipidation-mediated sorting of the autophagy-related protein LC3 to the ruffled border and attenuated lysosome-plasma membrane fusion. In this process, the interactions between coronin 1A and actin were crucial. Collectively, our findings indicate that coronin 1A is a pivotal component that regulates lysosomal fusion and the secretion pathway in osteoclast-lineage cells and may provide a novel therapeutic target for bone diseases.

Hepatic vagus nerve regulates Kupffer cell activation via α7 nicotinic acetylcholine receptor in nonalcoholic steatohepatitis.

BACKGROUND: Nonalcoholic fatty liver disease ranges from simple steatosis to nonalcoholic steatohepatitis (NASH). Kupffer cells play a central role in promoting hepatic inflammation, which leads to the development of NASH. We investigated the anti-inflammatory effect of hepatic vagus-mediated stimulation of the α7 nicotinic acetylcholine receptor (α7nAChR) on Kupffer cells in NASH pathogenesis. METHODS: Wild-type (WT) mice undergoing hepatic vagotomy (HV) were fed a methionine- and choline-deficient (MCD) diet for 1 week. α7nAChR knockout (α7KO) chimeric mice were generated by transplanting α7KO bone marrow cells into irradiated and Kupffer cell-deleted WT recipients. Kupffer cells were isolated from WT mice and treated with α7nAChR agonist under stimulation by lipopolysaccharide and/or palmitic acid. RESULTS: HV aggravated MCD diet-induced NASH in both steatosis and inflammation. The hepatic inflammatory response, including the upregulation of tumor necrosis factor alpha (TNFα), interleukin (IL)-12, and monocyte chemoattractant protein 1 (MCP-1), was accelerated in HV mice, accompanied by the downregulation of PPARα pathway genes. Kupffer cells were highly activated via the phosphorylation and nuclear translocation of nuclear factor-kappa B (NF-κB) in MCD diet-fed HV mice. The α7nAchR agonist suppressed the inflammatory response of primary Kupffer cells induced by lipopolysaccharide and palmitic acid by attenuating the NF-κB cascade. α7KO chimeric mice fed an MCD diet for 1 week developed advanced NASH with highly activated Kupffer cells. The hepatic expression of TNFα, IL-12, and MCP-1 was upregulated in α7KO chimeric mice, accompanied by abnormal lipid metabolism. CONCLUSIONS: Hepatic vagus activity regulates the inflammatory response of Kupffer cells via α7nAChR in NASH development.

Mice lacking the intracellular cation channel TRIC-B have compromised collagen production and impaired bone mineralization.

The trimeric intracellular cation (TRIC) channels TRIC-A and TRIC-B localize predominantly to the endoplasmic reticulum (ER) and likely support Ca(2+) release from intracellular stores by mediating cationic flux to maintain electrical neutrality. Deletion and point mutations in TRIC-B occur in families with autosomal recessive osteogenesis imperfecta. Tric-b knockout mice develop neonatal respiratory failure and exhibit poor bone ossification. We investigated the cellular defect causing the bone phenotype. Bone histology indicated collagen matrix deposition was reduced in Tric-b knockout mice. Osteoblasts, the bone-depositing cells, from Tric-b knockout mice exhibited reduced Ca(2+) release from ER and increased ER Ca(2+) content, which was associated with ER swelling. These cells also had impaired collagen release without a decrease in collagen-encoding transcripts, consistent with a defect in trafficking of collagen through ER. In contrast, osteoclasts, the bone-degrading cells, from Tric-b knockout mice were similar to those from wild-type mice. Thus, TRIC-B function is essential to support the production and release of large amounts of collagen by osteoblasts, which is necessary for bone mineralization.

HIF-1α-PDK1 axis-induced active glycolysis plays an essential role in macrophage migratory capacity.

In severely hypoxic condition, HIF-1α-mediated induction of Pdk1 was found to regulate glucose oxidation by preventing the entry of pyruvate into the tricarboxylic cycle. Monocyte-derived macrophages, however, encounter a gradual decrease in oxygen availability during its migration process in inflammatory areas. Here we show that HIF-1α-PDK1-mediated metabolic changes occur in mild hypoxia, where mitochondrial cytochrome c oxidase activity is unimpaired, suggesting a mode of glycolytic reprogramming. In primary macrophages, PKM2, a glycolytic enzyme responsible for glycolytic ATP synthesis localizes in filopodia and lammelipodia, where ATP is rapidly consumed during actin remodelling processes. Remarkably, inhibition of glycolytic reprogramming with dichloroacetate significantly impairs macrophage migration in vitro and in vivo. Furthermore, inhibition of the macrophage HIF-1α-PDK1 axis suppresses systemic inflammation, suggesting a potential therapeutic approach for regulating inflammatory processes. Our findings thus demonstrate that adaptive responses in glucose metabolism contribute to macrophage migratory activity.

B-cell survival and development controlled by the coordination of NF-κB family members RelB and cRel.

Targeted deletion of BAFF causes severe deficiency of splenic B cells. BAFF-R is commonly thought to signal to nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB)-inducing kinase dependent noncanonical NF-κB RelB. However, RelB-deficient mice have normal B-cell numbers. Recent studies showed that BAFF also signals to the canonical NF-κB pathway, and we found that both RelB and cRel are persistently activated, suggesting BAFF signaling coordinates both pathways to ensure robust B-cell development. Indeed, we report now that combined loss of these 2 NF-κB family members leads to impaired BAFF-mediated survival and development in vitro. Although single deletion of RelB and cRel was dispensable for normal B-cell development, double knockout mice displayed an early B-cell developmental blockade and decreased mature B cells. Despite disorganized splenic architecture in Relb(-/-)cRel(-/-) mice, generation of mixed-mouse chimeras established the developmental phenotype to be B-cell intrinsic. Together, our results indicate that BAFF signals coordinate both RelB and cRel activities to ensure survival during peripheral B-cell maturation.

Hepatic stellate cells relay inflammation signaling from sinusoids to parenchyma in mouse models of immune-mediated hepatitis.

UNLABELLED: Hepatic stellate cells (HSCs) constitute the liver sinusoid with Kupffer cells and liver sinusoidal endothelial cells. While the sinusoid functions as the gateway to liver inflammation, whether HSCs contribute to liver inflammation and, if so, how they exert such functions remain elusive. Here, we found that mouse as well as human HSCs expressed DP1 receptor for prostaglandin D2 selectively in the liver. Pharmacological stimulation of DP1 by BW245C, a DP1-selective agonist, suppressed the activation of cultured HSCs by tumor necrosis factor-α at least in part through down-regulation of nuclear factor kappa-light-chain-enhancer of activated B cells signaling and inhibition of c-Jun N-terminal kinase phosphorylation. DP1 deficiency or BW245C administration in mice significantly enhanced or suppressed concanavalin A (ConA)-induced hepatitis, respectively. ConA injection induced tumor necrosis factor-α and interferon-γ expression in the sinusoid, which was suppressed by administration of BW245C. Coculture of spleen cells and liver nonparenchymal cells showed that ConA first activated spleen cells and that this activation led to activation of nonparenchymal cells to secondarily produce tumor necrosis factor-α and interferon-γ. Microarray analysis revealed ConA-induced expression of endothelin-1, tissue factor, and chemokines in the liver and inducible nitric oxide synthase in hepatocytes, resulting in flow stagnation, leukocyte adherence and migration to the parenchyma, and hepatocyte death. DP1 stimulation inhibits all these events in the liver. Therefore, HSCs mediate amplification of ConA-induced liver inflammation in the sinusoid, causing direct and indirect hepatocyte injury, and DP1 stimulation inhibits this HSC activation. CONCLUSIONS: HSCs integrate cytokine-mediated inflammatory responses in the sinusoids and relay them to the liver parenchyma, and these HSC actions are inhibited by DP1 stimulation.

Efficient inhibition of tumor angiogenesis and growth by a synthetic peptide blocking S100A4-methionine aminopeptidase 2 interaction.

The prometastatic calcium-binding protein, S100A4, is expressed in endothelial cells, and its downregulation markedly suppresses tumor angiogenesis in a xenograft cancer model. Given that endothelial S100A4 can be a molecular target for inhibiting tumor angiogenesis, we addressed here whether synthetic peptide capable of blocking S100A4-effector protein interaction could be a novel antiangiogenic agent. To examine this hypothesis, we focused on the S100A4-binding domain of methionine aminopeptidase 2, an effector protein, which plays a role in endothelial cell growth. Overexpression of the domain in mouse endothelial MSS31 cells reduced DNA synthesis, and the corresponding synthetic peptide (named NBD) indeed interacted with S100A4 and inhibited capillary formation in vitro and new blood vessel formation in vivo. Intriguingly, a single intra-tumor administration of the NBD peptide in human prostate cancer xenografts significantly reduced vascularity, resulting in tumor regression. Mechanistically, the NBD peptide enhanced assembly of nonmuscle myosin IIA filaments along with Ser1943 phosphorylation, stimulated formation of focal adhesions without phosphorylation of focal adhesion kinase, and provoked G1/S arrest of the cell cycle. Altogether, the NBD peptide is a potent inhibitor for tumor angiogenesis, and is the first example of an anticancer peptide drug developed on the basis of an endothelial S100A4-targeted strategy.

Inhibition of MMP-2-Mediated Mast Cell Invasion by NF-κB Inhibitor DHMEQ in Mast Cells.

BACKGROUND: Stimulation with antigen and IgE is known to activate NF-κB in mast cells. In the present research, we studied the role of NF-κB on cellular migration in mast cell-like RBL-2H3 cells and bone marrow-derived mast cells (BMMCs) using the NF-κB inhibitor (-)-DHMEQ. METHODS: A Matrigel invasion chamber was used to evaluate cell migration. A PCR array was used to screen the expression of 84 key genes involved in cell migration. RESULTS: (-)-DHMEQ inhibited antigen/IgE-induced NF-κB activation and expressions of its target genes such as IL-6 and TNF-α. (-)-DHMEQ was found to inhibit in vitro invasion toward the antigen without any toxicity. We then looked for NF-κB-dependent genes that would be important for mast cell invasion using the PCR array. (-)-DHMEQ was found to lower the expression of matrix metalloproteinase (MMP)-2. The MMP inhibitor GM6001 also inhibited cellular invasion toward the antigen. These effects of (-)-DHMEQ were obtained in both RBL-2H3 cells and BMMCs. CONCLUSIONS: These findings indicate that (-)-DHMEQ suppressed mast cell migration via the inhibition of NF-κB-regulated MMP-2 expression.

Migration of splenic lymphocytes promotes liver fibrosis through modification of T helper cytokine balance in mice.

BACKGROUND: Sustained liver injury causes liver fibrosis and eventually cirrhosis. Understanding the pathophysiological mechanisms of liver fibrosis and interventions in the fibrotic process is crucial for improving the prognosis of patients with chronic liver diseases. Although studies have shown that splenectomy suppresses liver fibrosis, the mechanism by which this occurs is poorly understood. The present study focuses on the immunological functions of the spleen to investigate its role in liver fibrosis. METHODS: BALB/c and severe combined immunodeficiency (SCID) mice underwent splenectomies or sham operations prior to induction of liver fibrosis with carbon tetrachloride or thioacetamide. RESULTS: Sirius red staining and hydroxyproline assays showed that splenectomy suppressed liver fibrogenesis in BALB/c mice. Reverse transcription PCR analysis of T helper type 1 (Th1) and T helper type 2 (Th2) cytokines demonstrated that splenectomy shifted the Th1/Th2 balance in the liver towards Th1 dominance. In SCID mice, the inhibitory effect on liver fibrosis was abrogated. The number of CD4(+) T helper lymphocytes in the spleen decreased after liver injury. Green fluorescent protein positive (GFP(+)) splenocytes were transplanted into the spleens of syngeneic wild-type mice to trace their destination after fibrosis induction. GFP(+)CD4(+) lymphocytes appeared in the liver after induction of fibrosis, and flow cytometry revealed the vast majority of them were Th2 lymphocytes. Transfer of splenocytes via the portal vein into syngeneic splenectomized mice cancelled the suppressive effect of splenectomy on liver fibrosis. CONCLUSIONS: The present study demonstrated that Th2-dominant splenic lymphocytes migrate into the liver and promote liver fibrosis by shifting the cytokine balance towards Th2 dominance. Splenectomy suppresses the progression of fibrosis at least partly by restoring the Th1/Th2 balance.

Strategies to Detect Hepatic Myofibroblasts in Liver Cirrhosis of Different Etiologies.

Liver cirrhosis, a late stage of hepatic fibrosis, is an increasing cause of morbidity and mortality worldwide. Hepatic fibrosis is mainly caused by alcoholic or non-alcoholic steatohepatitis, chronic viral hepatitis, or autoimmune and biliary diseases. Myofibroblasts, which are absent from the normal liver, are differentiated from heterogeneous cell populations in response to a liver injury of any etiology and produce the extracellular matrix. Hepatic stellate cells are considered the main source of myofibroblasts. However, the origin of hepatic myofibroblasts remains unresolved, and despite considerable research, only a limited success has been achieved by existing anti-fibrotic therapies. The question remains whether these limitations are caused by lack of attention to the critical targets, the myofibroblasts derived from cells of other mesenchymal origins. Therefore, identifying the origin of myofibroblasts may provide insight into the mechanisms underlying liver fibrosis, and may lead to the development of more effective therapies. This review will examine our current strategies for detecting hepatic myofibroblasts of different origins.