Rho-kinase mediates lysophosphatidic acid-induced IL-8 and MCP-1 production via p38 and JNK pathways in human endothelial cells

FDCA Attenuates Neuroinflammation and Brain Injury after Cerebral Ischemic Stroke

Ischemic stroke is a deleterious cerebrovascular disease with few therapeutic options, and its functional recovery is highly associated with the integrity of the blood-brain barrier and neuroinflammation. The Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor fasudil (F) and the pyruvate dehydrogenase kinase (PDK) inhibitor dichloroacetate (DCA) have been demonstrated to exhibit neuroprotection in a series of neurological disorders. Hence, we synthesized and biologically examined the new salt fasudil dichloroacetate (FDCA) and validated that FDCA was eligible for attenuating ischemic volume and neurological deficits in the rat transient middle cerebral artery occlusion (tMCAO) model. Additionally, FDCA exerted superior effects than fasudil and dichloroacetate alone or in combination in reducing cerebral ischemic injury. Particularly, FDCA could maintain the blood-brain barrier (BBB) integrity by inhibiting matrix metalloproteinase 9 (MMP-9) protein expression and the degradation of zonula occludens (ZO-1) and Occludin protein. Meanwhile, FDCA could mitigate the neuroinflammation induced by microglia. The in vivo and in vitro experiments further demonstrated that FDCA disrupted the phosphorylations of myosin phosphatase target subunit 1 (MYPT1), mitogen-activated protein kinase (MAPK) cascade, including p38 and c-Jun N-terminal kinase (JNK), and pyruvate dehydrogenase (PDH) and limited excessive lactic acid metabolites, resulting in inhibition of BBB disruption and neuroinflammation. In addition, FDCA potently mitigated inflammatory response in human monocytes isolated from ischemic stroke patients, which provides the possibilities of a clinical translation perspective. Overall, these findings provided a therapeutic potential for FDCA as a candidate agent for ischemic stroke and other neurological diseases associated with BBB disruption and neuroinflammation.

Tight junctions: from molecules to gastrointestinal diseases

Intestinal epithelium functions as a tissue barrier to prevent interaction between the internal compartment and the external milieu. Intestinal barrier function also determines epithelial polarity for the absorption of nutrients and the secretion of waste products. These vital functions require strong integrity of tight junction proteins. In fact, intestinal tight junctions that seal the paracellular space can restrict mucosal-to-serosal transport of hostile luminal contents. Tight junctions can form both an absolute barrier and a paracellular ion channel. Although defective tight junctions potentially lead to compromised intestinal barrier and the development and progression of gastrointestinal (GI) diseases, no FDA-approved therapies that recover the epithelial tight junction barrier are currently available in clinical practice. Here, we discuss the impacts and regulatory mechanisms of tight junction disruption in the gut and related diseases. We also provide an overview of potential therapeutic targets to restore the epithelial tight junction barrier in the GI tract.

Commonalities Between ARDS, Pulmonary Fibrosis and COVID-19: The Potential of Autotaxin as a Therapeutic Target

Severe COVID-19 is characterized by acute respiratory distress syndrome (ARDS)-like hyperinflammation and endothelial dysfunction, that can lead to respiratory and multi organ failure and death. Interstitial lung diseases (ILD) and pulmonary fibrosis confer an increased risk for severe disease, while a subset of COVID-19-related ARDS surviving patients will develop a fibroproliferative response that can persist post hospitalization. Autotaxin (ATX) is a secreted lysophospholipase D, largely responsible for the extracellular production of lysophosphatidic acid (LPA), a pleiotropic signaling lysophospholipid with multiple effects in pulmonary and immune cells. In this review, we discuss the similarities of COVID-19, ARDS and ILDs, and suggest ATX as a possible pathologic link and a potential common therapeutic target.

The novel ORFV protein ORFV113 activates LPA-p38 signaling

Viruses have evolved mechanisms to subvert critical cellular signaling pathways that regulate a wide range of cellular functions, including cell differentiation, proliferation and chemotaxis, and innate immune responses. Here, we describe a novel ORFV protein, ORFV113, that interacts with the G protein-coupled receptor Lysophosphatidic acid receptor 1 (LPA1). Consistent with its interaction with LPA1, ORFV113 enhances p38 kinase phosphorylation in ORFV infected cells in vitro and in vivo, and in cells transiently expressing ORFV113 or treated with soluble ORFV113. Infection of cells with virus lacking ORFV113 (OV-IA82Δ113) significantly decreased p38 phosphorylation and viral plaque size. Infection of cells with ORFV in the presence of a p38 kinase inhibitor markedly diminished ORFV replication, highlighting importance of p38 signaling during ORFV infection. ORFV113 enhancement of p38 activation was prevented in cells in which LPA1 expression was knocked down and in cells treated with LPA1 inhibitor. Infection of sheep with OV-IA82Δ113 led to a strikingly attenuated disease phenotype, indicating that ORFV113 is a major virulence determinant in the natural host. Notably, ORFV113 represents the first viral protein that modulates p38 signaling via interaction with LPA1 receptor.

Thrombin impairs the angiogenic activity of extravillous trophoblast cells via monocyte chemotactic protein-1 (MCP-1): A possible link with preeclampsia

Cytokines' secretion from the decidua and trophoblast cells has been known to regulate trophoblast cell functions, such as Extravillous trophoblasts (EVTs) cell migration and invasion and remodeling of spiral arteries. Defective angiogenesis and spiral arteries transformation are mainly caused by proinflammatory cytokines and excessive thrombin generation during preeclampsia. Monocyte chemotactic protein-1 (MCP-1), a crucial cytokine, has a role in maintaining normal pregnancy. In this study, we explored whether thrombin regulates the secretion of MCP-1 in HTR-8/SVneo cells; if yes, what is its function? We used HTR-8/SVneo cells, developed from first trimester villous explants of early pregnancy, as the model of EVTs. MCP-1 gene silencing was performed using gene-specific siRNA. qPCR and ELISA were performed to estimate the expression and secretion of MCP-1. Here, we found that thrombin enhanced the secretion of MCP-1 in HTR-8/SVneo cells. Proteinase-activated receptor-1 (PAR-1) was found as the primary receptor, regulating MCP-1 secretion in these cells. Furthermore, MCP-1 secretion is modulated via protein kinase C (PKC) α, β, and Rho/Rho-kinase-dependent pathways. Thrombin negatively regulates HTR-8/SVneo cells' ability to mimic tube formation in an MCP-1 dependent manner. In conclusion, we propose that thrombin-controlled MCP-1 secretion may play an essential role in normal placental development and successful pregnancy maintenance. Improper thrombin production and MCP-1 secretion during pregnancy might cause inadequate vascular formation and transformation of spiral arteries, which may contribute to pregnancy disorders, such as preeclampsia.

Mechanical stiffness augments ligand-dependent progesterone receptor B activation via MEK 1/2 and Rho/ROCK-dependent signaling pathways in uterine fibroid cells

OBJECTIVE

To test whether mechanical substrate stiffness would influence progesterone receptor B (PRB) signaling in fibroid cells. Uterine fibroids feature an excessive extracellular matrix, increased stiffness, and altered mechanical signaling. Fibroid growth is stimulated by progestins and opposed by anti-progestins, but a functional interaction between progesterone action and mechanical signaling has not been evaluated.

DESIGN

Laboratory studies.

SETTING

Translational science laboratory.

PATIENT(S)/ANIMAL(S)

Human fibroid cell lines and patient-matched fibroid and myometrial cell lines.

INTERVENTION(S)

Progesterone receptor B-dependent reporter assays and messenger RNA quantitation in cells cultured on stiff polystyrene plates (3GPa) or soft silicone plates (930KPa). Pharmacologic inhibitors of extracellular signal-related protein kinase (ERK) kinase 1/2 (MEK 1/2; PD98059), p38 mitogen-activated protein kinase (SB202190), receptor tyrosine kinases (RTKs; nintedanib), RhoA (A13), and Rho-associated coiled-coil kinase (ROCK; Y27632).

MAIN OUTCOME MEASURE(S)

Progesterone-responsive reporter activation.

RESULT(S)

Fibroid cells exhibited higher PRB-dependent reporter activity with progesterone (P4) in cells cultured on stiff vs. soft plates. Mechanically induced PRB activation with P4 was decreased 62% by PD98059, 78% by nintedanib, 38% by A13, and 50% by Y27632. Overexpression of the Rho-guanine nucleotide exchange factor (Rho-GEF), AKAP13, significantly increased PRB-dependent reporter activity. Collagen 1 messenger RNA levels were higher in fibroid cells grown on stiff vs. soft plates with P4.

CONCLUSION(S)

Cells cultured on mechanically stiff substrates had enhanced PRB activation via a mechanism that required MEK 1/2 and AKAP13/RhoA/ROCK signaling pathways. These studies provide a framework to explore the mechanisms by which mechanical stiffness affects progesterone receptor activation.

Salidroside and isorhamnetin attenuate urotensin II-induced inflammatory response in vivo and in vitro: Involvement in regulating the RhoA/ROCK II pathway

Urotensin II (UII), a vital vasoconstrictor peptide, causes an inflammatory response in the pathogenesis of atherosclerosis. Previous studies have reported that the Ras homolog gene family, member A (RhoA)/Rho kinases (ROCK) pathway modulates the inflammatory response of the atherosclerotic process. However, to the best of our knowledge, whether the RhoA/ROCK pathway mediates the inflammatory effect of UII has not been previously elucidated. Salidroside and isorhamnetin are two early developed antioxidant Tibetan drugs, both displaying cardioprotective effects against atherosclerosis. Therefore, the aim of the present study was to investigate the protective effects of salidroside, isorhamnetin or combination of these two drugs on the UII-induced inflammatory response in vivo (rats) or in vitro [primary vascular smooth muscle cells (VSMCs)], as well as to examine the role of the RhoA/ROCK pathway in these processes. The levels of inflammatory markers were measured via ELISA. The mRNA and protein expression levels of RhoA and ROCK II were detected using reverse transcription-quantitative PCR assay and western blot analysis. It was demonstrated that salidroside, isorhamnetin and both in combination decreased the levels of the serum pro-inflammatory cytokines TNF-α and IL-1β, as well as increased the levels of the anti-inflammatory cytokine IL-10 and macrophage migration inhibitory factor in rats with subacute infusion of UII and in the culture supernatant from primary VSMCs-exposed to UII. Moreover, salidroside, isorhamnetin and both in combination attenuated the mRNA and protein expression levels of RhoA and ROCK II in vivo and in vitro, at concentrations corresponding to human therapeutic blood plasma concentrations. Thus, these drugs could inhibit the RhoA/ROCK II pathway under UII conditions. The combination of salidroside and isorhamnetin did not display a stronger inhibitory effect on the inflammatory response and the RhoA/ROCK II pathway compared with salidroside and isorhamnetin in isolation. Collectively, the results indicated that salidroside, isorhamnetin and both in combination inhibited the RhoA/ROCK II pathway, which then attenuated the inflammatory response under UII-induced conditions, resulting in cardioprotection in atherosclerosis.

Nonalcoholic Steatohepatitis Promoting Kinases

Nonalcoholic hepatitis (NASH) is the progressive inflammatory form of nonalcoholic fatty liver disease. Although the mechanisms of hepatic inflammation in NASH remain incompletely understood, emerging literature implicates the proinflammatory environment created by toxic lipid-induced hepatocyte injury, termed lipotoxicity. Interestingly, numerous NASH-promoting kinases in hepatocytes, immune cells, and adipocytes are activated by the lipotoxic insult associated with obesity. In the current review, we discuss recent advances in NASH-promoting kinases as disease mediators and therapeutic targets. The focus of the review is mainly on the mitogen-activated protein kinases including mixed lineage kinase 3, apoptosis signal-regulating kinase 1, c-Jun N-terminal kinase, and p38 MAPK; the endoplasmic reticulum (ER) stress kinases protein kinase RNA-like ER kinase and inositol-requiring protein-1α; as well as the Rho-associated protein kinase 1. We also discuss various pharmacological agents targeting these stress kinases in NASH that are under different phases of development.

Endothelial Dysfunction in Diabetes

Diabetes is a worldwide health issue closely associated with cardiovascular events. Given the pandemic of obesity, the identification of the basic underpinnings of vascular disease is strongly needed. Emerging evidence has suggested that endothelial dysfunction is a critical step in the progression of atherosclerosis. However, how diabetes affects the endothelium is poorly understood. Experimental and clinical studies have illuminated the tight link between insulin resistance and endothelial dysfunction. In addition, macrophage polarization from M2 towards M1 contributes to the process of endothelial damage. The possibility that novel classes of anti-hyperglycemic agents exert beneficial effects on the endothelial function and macrophage polarization has been raised. In this review, we discuss the current status of knowledge regarding the pathological significance of insulin signaling in endothelium. Finally, we summarize recent therapeutic strategies against endothelial dysfunction with an emphasis on macrophage polarity.

Deregulated Lysophosphatidic Acid Metabolism and Signaling in Liver Cancer

Liver cancer is one of the leading causes of death worldwide due to late diagnosis and scarcity of treatment options. The major risk factor for liver cancer is cirrhosis with the underlying causes of cirrhosis being viral infection (hepatitis B or C), metabolic deregulation (Non-alcoholic fatty liver disease (NAFLD) in the presence of obesity and diabetes), alcohol or cholestatic disorders. Lysophosphatidic acid (LPA) is a bioactive phospholipid with numerous effects, most of them compatible with the hallmarks of cancer (proliferation, migration, invasion, survival, evasion of apoptosis, deregulated metabolism, neoangiogenesis, etc.). Autotaxin (ATX) is the enzyme responsible for the bulk of extracellular LPA production, and together with LPA signaling is involved in chronic inflammatory diseases, fibrosis and cancer. This review discusses the most important findings and the mechanisms related to ATX/LPA/LPAR involvement on metabolic, viral and cholestatic liver disorders and their progression to liver cancer in the context of human patients and mouse models. It focuses on the role of ATX/LPA in NAFLD development and its progression to liver cancer as NAFLD has an increasing incidence which is associated with the increasing incidence of liver cancer. Bearing in mind that adipose tissue accounts for the largest amount of LPA production, many studies have implicated LPA in adipose tissue metabolism and inflammation, liver steatosis, insulin resistance, glucose intolerance and lipogenesis. At the same time, LPA and ATX play crucial roles in fibrotic diseases. Given that hepatocellular carcinoma (HCC) is usually developed on the background of liver fibrosis, therapies that both delay the progression of fibrosis and prevent its development to malignancy would be very promising. Therefore, ATX/LPA signaling appears as an attractive therapeutic target as evidenced by the fact that it is involved in both liver fibrosis progression and liver cancer development.

Resveratrol downregulates TNF-α-induced monocyte chemoattractant protein-1 in primary rat pulmonary artery endothelial cells by P38 mitogen-activated protein kinase signaling

Background: To evaluate the effects of resveratrol to monocyte chemoattractant protein-1 (MCP-1) and the role of p38 mitogen-activated protein kinase (MAPK) in this process in vitro.

Materials and methods: Animal acute pulmonary thromboembolism (PTE) model: rat model was established by infusion of an autologous blood clot into the pulmonary artery through a polyethylene catheter. One hundred and thirty-two rats were randomly and equally divided into ten groups: rats-control (untreated), rats-1% DMSO, rats-TNF-α, rats-TNF-α + resveratrol, rats-TNF-α +C1142, rats-TNF-α+SB203580, rats-TNF-α+resveratrol + SB203580, rats-resveratrol only, rats-C1142 only, and rats-SB203580 only. Rat pulmonary artery endothelial cells (RPAs) tests: RPAs were isolated from above animal and designated as: RPAs-control, RPAs-1% DMSO control, RPAs-TNF-α, RPAs-TNF-α + resveratrol, RPAs-TNF-α + C1142, RPAs-TNF-α + SB203580, RPAs-TNF-α + resveratrol + SB203580, RPAs-resveratrol only, RPAs-C1142 only, and RPAs-SB203580 only. Each group was further divided into 1, 4, and 8 hrs time point for evaluation (n=6 rats per time point) except RPAs-TNF-α + SB203580, RPAs-TNF-α + resveratrol + SB203580, RPAs-C1142 and RPAs-SB203580 only, which were evaluated at 8 hrs time point. At each time point, mRNA and protein expressions of RPAs of MCP-1 were measured. The phosphorylation of p38 MAPK (p-pMAPK) of RPAs was also detected.

Results: We found that the RPAs-TNF-α elicited significant increases in MCP-1 expression and phosphorylation of p38 mitogen-activated protein kinase (p-p38 MAPK). Furthermore, the MCP-1 expressions of RPAs-Resveratrol, RPAs-C1142, and RPAs-SB203580 were significantly down-regulated, which was associated with robustly suppressed TNF-α-induced p-p38MAPK expression.

Conclusion: Our findings suggested that MCP-1 was involved in the formation of TNF-α-induced inflammatory response, and resveratrol could down-regulate the expression of MCP-1 via TNF-α- inhibition, which might contribute to the decline of acute PTE-induced PH in vivo.

ROCK2 Regulates Monocyte Migration and Cell to Cell Adhesion in Vascular Endothelial Cells

The small GTPase Rho and its downstream effector, Rho-kinase (ROCK), regulate various cellular functions, including organization of the actin cytoskeleton, cell adhesion and migration. A pro-inflammatory lipid mediator, lysophosphatidic acid (LPA), is a potent activator of the Rho/ROCK signalling pathway and has been shown to induce the expression of chemokines and cell adhesion molecules (CAMs). In the present study, we aimed to elucidate the precise mechanism by which ROCK regulates LPA-induced expressions and functions of chemokines and CAMs. We observed that ROCK blockade reduced LPA-induced phosphorylation of IκBα and inhibited NF-κB RelA/p65 phosphorylation, leading to attenuation of RelA/p65 nuclear translocation. Furthermore, small interfering RNA-mediated ROCK isoform knockdown experiments revealed that LPA induces the expression of monocyte chemoattractant protein-1 (MCP-1) and E-selectin via ROCK2 in human aortic endothelial cells (HAECs). Importantly, we found that ROCK2 but not ROCK1 controls LPA-induced monocytic migration and monocyte adhesion toward endothelial cells. These findings demonstrate that ROCK2 is a key regulator of endothelial inflammation. We conclude that targeting endothelial ROCK2 is potentially effective in attenuation of atherosclerosis.

Rho-Associated Coiled-Coil Kinase (ROCK) in Molecular Regulation of Angiogenesis

Identified as a major downstream effector of the small GTPase RhoA, Rho-associated coiled-coil kinase (ROCK) is a versatile regulator of multiple cellular processes. Angiogenesis, the process of generating new capillaries from the pre-existing ones, is required for the development of various diseases such as cancer, diabetes and rheumatoid arthritis. Recently, ROCK has attracted attention for its crucial role in angiogenesis, making it a promising target for new therapeutic approaches. In this review, we summarize recent advances in understanding the role of ROCK signaling in regulating the permeability, migration, proliferation and tubulogenesis of endothelial cells (ECs), as well as its functions in non-ECs which constitute the pro-angiogenic microenvironment. The therapeutic potential of ROCK inhibitors in angiogenesis-related diseases is also discussed.

Lysophosphatidic acid enhances breast cancer cells-mediated osteoclastogenesis

Lysophosphatidic acid (LPA) is known to play a critical role in breast cancer metastasis to bone. In this study, we tried to investigate any role of LPA in the regulation of osteoclastogenic cytokines from breast cancer cells and the possibility of these secretory factors in affecting osteoclastogenesis. Effect of secreted cytokines on osteoclastogenesis was analyzed by treating conditioned media from LPA-stimulated breast cancer cells to differentiating osteoclasts. Result demonstrated that IL-8 and IL-11 expression were upregulated in LPA-treated MDA-MB-231 cells. IL-8 was induced in both MDA-MB-231 and MDA-MB-468, however, IL-11 was induced only in MDA-MB-231, suggesting differential LPARs participation in the expression of these cytokines. Expression of IL-8 but not IL-11 was suppressed by inhibitors of PI3K, NFkB, ROCK and PKC pathways. In the case of PKC activation, it was observed that PKCδ and PKCμ might regulate LPA-induced expression of IL-11 and IL-8, respectively, by using specific PKC subtype inhibitors. Finally, conditioned Medium from LPA-stimulated breast cancer cells induced osteoclastogenesis. In conclusion, LPA induced the expression of osteolytic cytokines (IL-8 and IL-11) in breast cancer cells by involving different LPA receptors. Enhanced expression of IL-8 by LPA may be via ROCK, PKCu, PI3K, and NFkB signaling pathways, while enhanced expression of IL-11 might involve PKCδ signaling pathway. LPA has the ability to enhance breast cancer cells-mediated osteoclastogenesis by inducing the secretion of cytokines such as IL-8 and IL-11.

Inhibition of lysophosphatidic acid receptor ameliorates Sjögren's syndrome in NOD mice

Lysophosphatidic acid (LPA), a bioactive lysophospholipid, is involved in the pathogenesis of chronic inflammatory and autoimmune diseases. In this study, we investigated the role of LPA/LPA receptor (LPAR) signaling in the pathogenesis of Sjögren's syndrome (SS). We found that autotaxin, an LPA producing enzyme, and LPAR1 and LPAR3 mRNA, and IL-17 mRNA were highly expressed in the exocrine glands of 20-week-old nonobese diabetic (NOD) mice, which show SS symptoms at this age, as compared with non-symptomatic 8-week-old NOD mice. In an adoptive transfer model using NOD lymphocytes, treatment with Ki16425, an LPAR1/3 antagonist, restored tear and saliva secretion and decreased symptoms of SS compared with the vehicle-treated group. IL-17 levels in serum and lacrimal glands were also significantly reduced by Ki16425 in recipient mice. In addition, Ki16425 treatment of 20-week-old NOD mice, which spontaneously developed SS, restored saliva volume. Treatment of NOD splenocytes with LPA induced the expression of IL-17 in a dose-dependent manner, and Ki16425 inhibited this increase. LPA stimulated the activation of ROCK2 and p38 MAPK; and inhibition of ROCK2 or p38 MAPK suppressed LPA-induced IL-17 expression. Our data suggest that LPAR signaling stimulates SS development by induction of IL-17 production via ROCK and p38 MAPK pathways. Thus, LPAR inhibition could be a possible therapeutic strategy for SS.

LYSOPHOSPHATIDIC ACIDS AND AUTOTAXIN IN RETINAL VEIN OCCLUSION

PURPOSE

To analyze the levels of lysophosphatidic acids (LPAs) and autotaxin (ATX) in undiluted vitreous of untreated patients with retinal vein occlusion (RVO).

METHODS

Sixty-four vitreous samples (40 RVO, 24 controls with idiopathic floaters) were analyzed in this retrospective case series using LC/MS for LPAs 16:0, 18:0, 18:1, 20:4, and ELISA kits or Luminex technology for ATX, angiopoetin-1 (ANG-1), interleukin-6 (IL-6), interleukin-7 (IL-7), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), pigment epithelium-derived factor (PEDF), and vascular endothelial growth factor (VEGF). LPA and ATX levels were correlated with the visual acuity, central macular thickness (CMT), average retinal thickness (AvT), vitreal cytokine levels and with each other.

RESULTS

Levels of every LPA species tested and ATX were significantly increased in the vitreous fluid from all patients with RVO (total LPAs: 968.0 ± 842.3 nM; ATX: 2.5 ± 1.02 nM) compared with controls (total LPAs: 225.2 ± 292.8 nM, P < 0.0001; ATX: 1.9 ± 1.00 nM, P = 0.005). There were strong positive correlations between the vitreal levels of IL-6, IL-8, MCP-1, VEGF and LPAs.

CONCLUSION

Levels of LPAs and ATX were positively correlated with proinflammatory cytokines and VEGF and might thus play an important role in the development of macular edema secondary to RVO.

Reversal of Bone Marrow Mobilopathy and Enhanced Vascular Repair by Angiotensin-(1-7) in Diabetes

The angiotensin (ANG)-(1-7)/Mas receptor (MasR) pathway activates vascular repair-relevant functions of bone marrow progenitor cells. We tested the effects of ANG-(1-7) on mobilization and vasoreparative functions of progenitor cells that are impaired in diabetes. The study was performed in streptozotocin-induced diabetic (db/db) mice. Diabetes resulted in a decreased number of Lineage^-Sca-1⁺c-Kit⁺ (LSK) cells in the circulation, which was normalized by ANG-(1-7). Diabetes-induced depletion of LSK cells in the bone marrow was reversed by ANG-(1-7). ρ-Kinase (ROCK) activity was increased specifically in bone marrow LSK cells by ANG-(1-7) in diabetes, and the beneficial effects of ANG-(1-7) were prevented by fasudil. ANG-(1-7) increased Slit3 levels in the bone marrow supernatants, which activated ROCK in LSK cells and sensitized them for stromal-derived factor-1α (SDF)-induced migration. Diabetes prevented the mobilization of LSK cells in response to ischemia and impaired the recovery of blood flow, both of which were reversed by ANG-(1-7) in both models of diabetes. Genetic ablation of MasR prevented ischemia-induced mobilization of LSK cells and impaired blood flow recovery, which was associated with decreased proliferation and migration of LSK cells in response to SDF or vascular endothelial growth factor. These results suggest that MasR is a promising target for the treatment of diabetic bone marrow mobilopathy and vascular disease.

Simultaneous Rho kinase inhibition in circulating leukocytes and in cardiovascular tissue in rats with high angiotensin converting enzyme levels

BACKGROUND

The small guanosine triphosphatase RhoA and its direct target Rho kinase (ROCK) play important roles in cardiovascular pathophysiology. Activated ROCK phosphorylates intracellular proteins with detrimental effects on cardiovascular remodeling. Increased ROCK activity in circulating leukocytes is observed in hypertension and in heart failure, but its relationship with ROCK activation in the myocardium and vessels is unknown. We hypothesized that ROCK activation and phosphorylation/activation of some of its key downstream molecules in the heart and arterial wall are reflected in circulating leukocytes.

METHODS

Phosphorylation of MYPT1, ERM and p38-MAPK and levels of p65-NF-κB were determined in the left ventricle (LV), aortic wall and circulating leukocytes in rats with high (Brown Norway, BN) and low (Lewis) angiotensin converting enzyme. A group of BN rats received the ROCK inhibitor fasudil (7days).

RESULTS

Compared to Lewis rats, in the BN group phosphorylated levels of MYPT1, ERM and p38-MAPK and levels of p65-NF-κB were increased (P<0.05) in the LV (67%, 92%, 52% and 98%, respectively); in the aortic wall (57%, 51%, 68% and 66%, respectively) and in circulating leukocytes (61%, 72%, 49% and 105%, respectively). Fasudil reduced all these levels to those observed in Lewis rats. Phosphorylated MYPT1, ERM, and p38-MAPK and levels of p65-NF-κB in circulating leukocytes were significantly correlated with their respective LV and aortic wall levels (excepting p65-NF-κB in aorta).

CONCLUSION

ROCK activity in circulating leukocytes reflects activation of this signaling pathway in the myocardium and aortic wall in this model, and supports its value as a potential cardiovascular remodeling marker.

Citron Rho-interacting kinase mediates arsenite-induced decrease in endothelial nitric oxide synthase activity by increasing phosphorylation at threonine 497: Mechanism underlying arsenite-induced vascular dysfunction

We reported that arsenite causes an acute decrease in nitric oxide (NO) production by increasing phosphorylation of endothelial NO synthase at threonine 497 (eNOS-Thr(497)); however, the detailed mechanism has not yet been clarified. Here, we investigated the kinase involving in arsenite-stimulated eNOS-Thr(497) phosphorylation. Although treatment with H-89, a known protein kinase A (PKA) inhibitor, inhibited arsenite-stimulated eNOS-Thr(497) phosphorylation, no inhibition was found in cells treated with other PKA inhibitors, including Rp-8-Br-cAMPS or PKI. Based on previous reports, we also tested whether RhoA mediates arsenite-stimulated eNOS-Thr(497) phosphorylation and found that arsenite causes an acute increase in RhoA activity. Ectopic expression of dominant negative (DN)-RhoA significantly reversed arsenite-stimulated eNOS-Thr(497) phosphorylation. An in vitro phosphorylation assay also revealed that the well-known Rho effectors, Rho-associated protein kinase 1/2 (ROCK1/2), directly phosphorylate eNOS-Thr(497). Y27632, a selective ROCK inhibitor, reversed arsenite-stimulated eNOS-Thr(497) phosphorylation. However, overexpression of a small interfering RNA (siRNA) against ROCK1/2 or DN-ROCK did not reverse arsenite-stimulated eNOS-Thr(497) phosphorylation, thereby providing no conclusive evidence of a role for ROCK1/2. Knockdown of PKC-related protein kinase 1/2, another Rho effector, also did not reverse arsenite-stimulated eNOS-Thr(497) phosphorylation. In contrast, we found that transfection with an siRNA against citron Rho-interacting kinase (CRIK), the other downstream effector of Rho, significantly reversed the arsenite-induced eNOS-Thr(497) phosphorylation that was accompanied by restoration of eNOS enzymatic activity repressed by arsenite. Moreover, CRIK directly phosphorylated eNOS-Thr(497)in vitro. Finally, we also found that arsenite increased eNOS-Thr(497) phosphorylation and decreased acetylcholine-induced vessel relaxation in rat aortas. In conclusion, we demonstrate that arsenite acutely inhibits eNOS enzymatic activity and vessel relaxation in part by increasing the RhoA/CRIK/eNOS-Thr(497) phosphorylation signaling axis, which provides a molecular mechanism underlying arsenite-induced impaired vascular diseases.

ROCK insufficiency attenuates ozone-induced airway hyperresponsiveness in mice

Ozone causes airway hyperresponsiveness (AHR) and pulmonary inflammation. Rho kinase (ROCK) is a key regulator of smooth muscle cell contraction and inflammatory cell migration. To determine the contribution of the two ROCK isoforms ROCK1 and ROCK2 to ozone-induced AHR, we exposed wild-type, ROCK1(+/-), and ROCK2(+/-) mice to air or ozone (2 ppm for 3 h) and evaluated mice 24 h later. ROCK1 or ROCK2 haploinsufficiency did not affect airway responsiveness in air-exposed mice but significantly reduced ozone-induced AHR, with a greater reduction in ROCK2(+/-) mice despite increased bronchoalveolar lavage (BAL) inflammatory cells in ROCK2(+/-) mice. Compared with wild-type mice, ozone-induced increases in BAL hyaluronan, a matrix protein implicated in ozone-induced AHR, were lower in ROCK1(+/-) but not ROCK2(+/-) mice. Ozone-induced increases in other inflammatory moieties reported to contribute to ozone-induced AHR (IL-17A, osteopontin, TNFα) were not different in wild-type vs. ROCK1(+/-) or ROCK2(+/-) mice. We also observed a dose-dependent reduction in ozone-induced AHR after treatment with the ROCK1/ROCK2 inhibitor fasudil, even though fasudil was administered after induction of inflammation. Ozone increased pulmonary expression of ROCK2 but not ROCK1 or RhoA. A ROCK2 inhibitor, SR3677, reduced contractile forces in primary human airway smooth muscle cells, confirming a role for ROCK2 in airway smooth muscle contraction. Our results demonstrate that ozone-induced AHR requires ROCK. Whereas ROCK1-dependent changes in hyaluronan may contribute to ROCK1's role in O3-induced AHR, the role of ROCK2 is downstream of inflammation, likely at the level of airway smooth muscle contraction.

The effect of ROCK on TNF-α-induced CXCL8 secretion by intestinal epithelial cell lines is mediated through MKK4 and JNK signaling

Intestinal epithelial cells (IEC) play a role in mucosal inflammatory responses by producing important chemokines like CXCL8 when stimulated by TNF-α. Previously, we found that IEC cell lines required the Rho-associated kinase, ROCK, for CXCL8 responses after IL-1 stimulation. This study extends these findings by showing that inhibiting ROCK suppressed TNF-α-induced CXCL8 secretion by Caco-2 and DLD1 colonic epithelial cell lines and CXCL8 mRNA levels in Caco-2 cells. RNAi knockdown experiments indicated that the inhibitory effect was mediated by ROCK2, and not ROCK1. Inhibiting ROCK had no effect on TNF-stimulated IκBα phosphorylation and degradation or p38 MAPK phosphorylation indicating that ROCK plays no role in these signaling pathways. However, inhibiting ROCK suppressed TNF-induced phosphorylation of the p54 JNK isoform and phosphorylation of the upstream MKK4 kinase. These results suggest that ROCK is required for CXCL8 responses by TNF-stimulated IEC by affecting intracellular signaling through MKK4 and JNK.

Expression of bioactive lysophospholipids and processing enzymes in the vitreous from patients with proliferative diabetic retinopathy

Background

The bioactive lysophospholipids phosphatidic acid (PA), lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) have been implicated in mediating cell migration, proliferation and apoptosis, inflammation, angiogenesis and fibrosis. This study was conducted to measure the levels of PA, LPA, LPA-producing enzymes phospholipase A1/A2 (PLA1A/PLA2, respectively) and acylgylycerol kinase (AGK), the S1P receptor S1PR1, the S1P catabolising enzyme S1P lyase (SPL) and 5-lipoxygenase in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR). In addition, we investigated the correlations between the levels of PA and LPA and the levels of the inflammatory and endothelial dysfunction biomarker soluble vascular cell adhesion molecule-1 (sVCAM-1).

Methods

Vitreous samples from 34 PDR and 29 nondiabetic patients were studied by biochemical and enzyme-linked immunosorbent assays and Western blot analysis.

Results

PA, LPA and sVCAM-1 levels in vitreous samples from PDR patients were significantly higher than those in nondiabetic patients. Significant correlations were observed between levels of LPA and levels of PA and sVCAM-1. Western blot analysis revealed a significant increase in the expression of PLA1A, AGK, S1PR1 and SPL in vitreous samples from PDR patients compared to nondiabetic controls, whereas PLA2 and 5-lipoxygenase were not detected.

Conclusions

Our findings suggest that the enzymatic activities of PLA1A and AGK might be responsible for increased synthesis of LPA in PDR and that PLA1A, but not PLA2 is responsible for deacylation of PA to generate LPA. S1PR1 and SPL might regulate inflammatory, angiogenic and fibrogenic responses in PDR.

Lysophosphatidic acid-induced IL-8 secretion involves MSK1 and MSK2 mediated activation of CREB1 in human fibroblast-like synoviocytes

Lysophosphatidic acid (LPA) is a pleiotropic lipid mediator that promotes motility, survival, and the synthesis of chemokines/cytokines such as interleukin-8 (IL-8) and interleukin-6 by human fibroblast-like synoviocytes from patients with rheumatoid arthritis (RAFLS). In those cells LPA was reported to induce IL-8 secretion through activation of various signaling pathways including p38 mitogen-activated protein kinase (p38 MAPK), p42/44 MAPK, and Rho kinase. In addition to those pathways we report that mitogen- and stress-activated protein kinases (MSKs) known to be activated downstream of the ERK1/2 and p38 MAPK cascades and CREB are phosphorylated in response to LPA. The silencing of MSKs with small-interfering RNAs and the pharmacological inhibitor of MSKs SB747651A shows a role for both MSK1 and MSK2 in LPA-mediated phosphorylation of CREB at Ser-133 and secretion of IL-8 and MCP-1. Whereas CREB inhibitors have off target effects and increased LPA-mediated IL-8 secretion, the silencing of CREB1 with short hairpin RNA significantly reduced LPA-induced chemokine production in RAFLS. Taken together the data clearly suggest that MSK1 and MSK2 are the major CREB kinases in RAFLS stimulated with LPA and that phosphorylation of CREB1 at Ser-133 downstream of MSKs plays a significant role in chemokine production.

Autotaxin and lysophosphatidic acid signalling in lung pathophysiology

Autotaxin (ATX or ENPP2) is a secreted glycoprotein widely present in biological fluids. ATX primarily functions as a plasma lysophospholipase D and is largely responsible for the bulk of lysophosphatidic acid (LPA) production in the plasma and at inflamed and/or malignant sites. LPA is a phospholipid mediator produced in various conditions both in cells and in biological fluids, and it evokes growth-factor-like responses, including cell growth, survival, differentiation and motility, in almost all cell types. The large variety of LPA effector functions is attributed to at least six G-protein coupled LPA receptors (LPARs) with overlapping specificities and widespread distribution. Increased ATX/LPA/LPAR levels have been detected in a large variety of cancers and transformed cell lines, as well as in non-malignant inflamed tissues, suggesting a possible involvement of ATX in chronic inflammatory disorders and cancer. In this review, we focus exclusively on the role of the ATX/LPA axis in pulmonary pathophysiology, analysing the effects of ATX/LPA on pulmonary cells and leukocytes in vitro and in the context of pulmonary pathophysiological situations in vivo and in human diseases.

Expression of lysophosphatidic acid, autotaxin and acylglycerol kinase as biomarkers in diabetic retinopathy

The proinflammatory lysophosphatidic acid (LPA) is a potent activator of several transcriptional factors and signaling pathways and a potent modulator of genes involved in inflammation, angiogenesis and fibrosis. This study was conducted to measure the levels of LPA and LPA-producing enzymes, autotaxin (ATX) and acylglycerol kinase (AGK) in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR) and to correlate their levels with clinical disease activity and the level of vascular endothelial growth factor (VEGF). In addition, we examined the expression of ATX, AGK and VEGF receptor-2 (VEGFR-2) in the retinas of diabetic rats. Vitreous samples from 42 PDR and 35 nondiabetic patients were studied by enzyme-linked immunosorbent assay. Vitreous samples and retinas of rats were examined by Western blot analysis. VEGF, LPA and AGK levels in vitreous samples from PDR patients were significantly higher than those in control patients without diabetes (p < 0.001 for all comparisons). ATX levels in PDR with active neovascularization and inactive PDR were significantly lower than those in nondiabetic patients (p = 0.045). Mean VEGF and AGK levels in PDR with active neovascularization were significantly higher than those in inactive PDR and nondiabetic patients (p < 0.001 for both comparisons). A significant correlation was observed between levels of VEGF and levels of AGK in PDR patients (r = 0.954; p < 0.001). Western blot analysis revealed a significant increase in the expression of AGK and VEGFR-2 in vitreous samples and the retinas of diabetic rats compared to nondiabetic controls, whereas ATX was significantly downregulated. Our findings suggest that ATX-AGK-LPA signaling axis might be an important player in the development and progression of diabetic retinopathy.

Metabolic inflammation: connecting obesity and insulin resistance

Insulin resistance is a pathological condition that arises when insulin signaling is impaired, forcing β-cells to produce more insulin in order to cope with body demands and to maintain glucose homeostasis. When the pancreas is no more able to support an appropriate insulin secretion, insulin resistance becomes decompensated and hyperglycemia is detected. One of the mechanisms leading to insulin resistance is low-grade inflammation that involves a number of protagonists such as inflammatory cytokines, lipids and their metabolites, reactive oxygen species (ROS), hypoxia and endoplasmic reticulum stress, and changes in gut microbiota profiles. We review here the molecular aspects of metabolic inflammation converging to insulin resistance and secondarily to type 2 diabetes. We also discuss the place of high-sensitivity C-reactive protein (hsCRP) in the assessment of metabolic inflammation and potential therapeutic interventions aimed to impede inflammation and therefore prevent insulin resistance.

Platelet-derived growth factor (PDGF)-BB-mediated induction of monocyte chemoattractant protein 1 in human astrocytes: implications for HIV-associated neuroinflammation

Chemokine (C-C motif) ligand 2, also known as monocyte chemoattractant protein 1 (MCP-1) is an important factor for the pathogenesis of HIV-associated neurocognitive disorders (HAND). The mechanisms of MCP-1-mediated neuropathogenesis, in part, revolve around its neuroinflammatory role and the recruitment of monocytes into the central nervous system (CNS) via the disrupted blood-brain barrier (BBB). We have previously demonstrated that HIV-1/HIV-1 Tat upregulate platelet-derived growth factor (PDGF)-BB, a known cerebrovascular permeant; subsequently, the present study was aimed at exploring the regulation of MCP-1 by PDGF-BB in astrocytes with implications in HAND. Specifically, the data herein demonstrate that exposure of human astrocytes to HIV-1 LAI elevated PDGF-B and MCP-1 levels. Furthermore, treating astrocytes with the human recombinant PDGF-BB protein significantly increased the production and release of MCP-1 at both the RNA and protein levels. MCP-1 induction was regulated by activation of extracellular-signal-regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinases and phosphatidylinositol 3-kinase (PI3K)/Akt pathways and the downstream transcription factor, nuclear factor κB (NFκB). Chromatin immunoprecipitation (ChIP) assays demonstrated increased binding of NFκB to the human MCP-1 promoter following PDGF-BB exposure. Conditioned media from PDGF-BB-treated astrocytes increased monocyte transmigration through human brain microvascular endothelial cells (HBMECs), an effect that was blocked by STI-571, a tyrosine kinase inhibitor (PDGF receptor (PDGF-R) blocker). PDGF-BB-mediated release of MCP-1 was critical for increased permeability in an in vitro BBB model as evidenced by blocking antibody assays. Since MCP-1 is linked to disease severity, understanding its modulation by PDGF-BB could aid in understanding the proinflammatory responses in HAND. These results suggest that astrocyte activation by PDGF-BB exaggerates monocyte recruitment into the brain via MCP-1 and underscores the critical role astrocytes play in HAND.

Rho-kinase-dependent pathway mediates the hepatoprotective effects of sorafenib against ischemia/reperfusion liver injury in rats with nonalcoholic steatohepatitis

During liver transplantation, nonalcoholic steatohepatitis (NASH) aggravates ischemia/reperfusion (IR) injury by activating various kinases and subsequently releasing cytokines and chemokines. Nonetheless, the effect of the multikinase inhibitor sorafenib on IR liver injury in rats with NASH has never been explored. Our study was designed to determine this effect and associated mechanisms in NASH rats. Sorafenib was acutely administered to NASH rats with IR liver injury that were or were not chronically pretreated with the Rho-kinase-specific inhibitor fasudil. Then, the following were evaluated: mean arterial pressure; hepatic blood flow and microcirculatory dysfunction; hepatic inflammation (serum alanine aminotransferase); necrosis; apoptosis; leukocyte infiltration; CD45 staining; caspase levels and DNA fragmentation; various serum and hepatic cytokines; and proteins and genes of the Raf/mitogen-activated protein-extracellular signal-regulated kinase kinase (MEK)/extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase, and apoptosis pathways. In NASH rats with IR liver injury, hepatic inflammation, necrosis, apoptosis, leukocyte infiltration, and microcirculatory dysfunction were significantly attenuated by the acute administration of sorafenib through the inhibition of the hepatic release of macrophage inflammatory protein 2, keratinocyte chemoattractant, granulocyte-monocyte colony-stimulating factor, and hepatic caspase-3 and caspase-9 as well as DNA fragmentation. Furthermore, there was decreased expression of p-Raf1 (where p indicates the phosphorylated form), p-MEK1/2, p-ERK1/2, p-Rho-kinase, B cell lymphoma 2-associated death promoter, and B cell lymphoma 2-associated X protein at the protein and messenger RNA levels. Notably, the aforementioned beneficial effects of sorafenib were significantly abolished by chronic pretreatment with the Rho-kinase-specific inhibitor fasudil. This study demonstrated that the multikinase inhibitor sorafenib protects NASH rats from IR injury by interfering with the inflammation, necrotic, and apoptotic responses causing leukocyte-dependent hepatic microcirculatory dysfunction. The hepatoprotective effects of sorafenib seem to work through the inhibition of the Rho-kinase-dependent Raf/MEK/ERK pathway, which is up-regulated during IR injury in the livers of NASH rats.

ROCKs as immunomodulators of stroke

INTRODUCTION

Stroke is the third leading cause of death and a major cause of long-term disability in the adult population. Growing evidence suggests that inflammation may play an important role in the evolution of stroke. Because Rho-associated coiled-coil containing kinases (ROCKs) are important mediators of inflammation, they may contribute to stroke and stroke recovery.

AREAS COVERED

The pathophysiological role of ROCKs in mediating inflammation at different phases of stroke, and the therapeutic opportunities for stroke prevention and stroke treatment with ROCK inhibitors will be discussed.

EXPERT OPINION

Inflammation is a double-edged sword during the evolution of stroke. Immunomodulation might provide a novel therapeutic approach for stroke prevention and stroke treatment. ROCK plays an important role in mediating the inflammatory response following vascular injury as well as platelet activation and thrombus formation. ROCK inhibitors have been shown to be beneficial in stroke prevention, acute neuroprotection and chronic stroke recovery by affecting inflammatory-mediated platelet and endothelial function, smooth muscle contraction and neuronal regeneration. Thus, ROCK-mediated inflammation could be a potential therapeutic target for stroke prevention and stroke treatment. However, the mechanism by which ROCKs regulate the inflammatory response is unclear, and the role of the two ROCK isoforms in stroke and stroke recovery remains to be determined.

Serum proteomic, peptidomic and metabolomic profiles in myasthenia gravis patients during treatment with Qiangji Jianli Fang

Background

Qiangji Jianli Fang (QJF) has been used for treatment of myasthenia gravis (MG) in China. However, our understanding of the effects of QJF against MG at the molecular level is limited. This study aims to investigate the effects of QJF treatment of MG patients on the protein, peptide and metabolite levels in serum.

Methods

High-throughput proteomic, peptidomic and metabolomic techniques were applied to investigate serum samples from 21 healthy individuals and 47 MG patients before and after QJF treatment via two-dimensional gel electrophoresis, matrix-assisted laser desorption/ionization time of flight mass spectrometry and liquid chromatography Fourier transform mass spectrometry, respectively.

Results

After QJF treatment, the expression levels of peptides m/z 1865.019, 2021.128 and 1211.668 of complement C3f increased (P = 0.004, P = 0.001 and P = 0.043, respectively), while that of peptide m/z 1739.931 of component C4b decreased (P = 0.043), in the serum of MG patients. The levels of γ-aminobutyric acid (P = 0.000) and coenzyme Q4 (P = 0.000) resumed their normal states.

Conclusion

QJF could inhibit the activity of the complement system and restore the normal levels of metabolites.

Resveratrol downregulates acute pulmonary thromboembolism-induced pulmonary artery hypertension via p38 mitogen-activated protein kinase and monocyte chemoattractant protein-1 signaling in rats

AIMS

In the present study, we explored the hypothesis that initiation of PH involves the upregulation of monocyte chemoattractant protein-1 (MCP-1) in acute PTE. We evaluated the effects of resveratrol and the role of p38 mitogen-activated protein kinase (MAPK) in this process.

MAIN METHODS

A rat model of acute PTE was established by infusion of an autologous blood clot into the pulmonary artery through a polyethylene catheter. Rats were randomly divided into 1, 4, and 8 hour time groups. Resveratrol, C1142 (a rodent chimeric mAb that neutralizes rat MCP-1) or SB203580 (a p38MAPK specific inhibitor) was administered to the animals beginning 1 h prior to the start of the acute PTE protocol. At each time point, the mean pulmonary artery pressure (mPAP), mRNA and protein expressions of MCP-1 were measured. The phosphorylation of p38 MAPK (p-pMAPK) was also detected.

KEY FINDINGS

Acute PTE elicited significant increases in mean pulmonary artery pressure (mPAP), and up-regulated the expression of monocyte chemoattractant protein-1 (MCP-1) and phosphorylation of p38 mitogen-activated protein kinase (p-p38 MAPK). Administration of C1142 markedly reduced mPAP. Furthermore, pre-treatment of rats with resveratrol significantly reduced mPAP and down-regulated the expression of MCP-1, which was associated with robustly suppressed acute PTE-induced p-p38MAPK expression.

SIGNIFICANCE

These findings suggested that MCP-1 was involved in the formation of acute PTE-induced PH, and resveratrol down-regulated the expression of MCP-1 by inhibiting acute PTE-induced p-p38MAPK activation, which contributed to the decrease in PH.

Lysophosphatidic acid induces lymphangiogenesis and IL-8 production in vitro in human lymphatic endothelial cells

The bioactive phospholipid lysophosphatidic acid (LPA) and its receptors LPA(1-3) are aberrantly expressed in many types of human cancer. LPA has been reported to induce tumor cell proliferation, migration, and cytokine production. However, whether LPA exerts an effect on lymphatic endothelial cells (LECs) or on lymphangiogenesis, a process of new lymphatic vessel formation that is associated with increased metastasis and poor prognosis in cancer patients, has been unknown. Here, we show that LPA induces cell proliferation, survival, migration, and tube formation, and promotes lymphangiogenesis in vitro in human dermal LECs. In addition, LPA induces IL-8 expression by enhancing IL-8 promoter activity via activation of the NF-κB pathway in LECs. Using IL-8 siRNA and IL-8 neutralizing antibody, we revealed that IL-8 plays an important role in LPA-induced lymphangiogenesis in vitro. Moreover, using siRNA inhibition, we discovered that LPA-induced lymphangiogenesis in vitro and IL-8 production are mediated via the LPA(2) receptor in LECs. Finally, using human sentinel afferent lymphatic vessel explants, we demonstrated that LPA up-regulates IL-8 production in the LECs of lymphatic endothelia. These studies provide the first evidence that LPA promotes lymphangiogenesis and induces IL-8 production in LECs; we also reveal a possible new role of LPA in the promotion of tumor progression, as well as metastasis, in different cancer types.

FGF-2- and TGF-β1-induced downregulation of lumican and keratocan in activated corneal keratocytes by JNK signaling pathway

PURPOSE

Downregulation of lumican and keratocan expression is an undesirable phenotypic change that occurs during corneal wound healing. The present study was intended to determine whether the activation of Jun N-terminal kinase (JNK)-signaling pathway is involved in their downregulation in TGF-β1- and FGF-2-activated keratocytes.

METHODS

Keratocytes, isolated from rabbit corneal stroma, and cultured in a serum-free medium, pretreated or not treated with JNK inhibitor (SP600125), were activated with FGF-2/heparin sulfate (HS) or TGF-β1 in the presence or absence of SP600125. In another set of experiments, keratocytes were transfected with JNK1/2 Dicer-substrate RNA (DsiRNA) and then activated with TGF-β1 or FGF-2/HS. Specific phenotypic changes were analyzed immunocytochemically and correlated with Western blot analyses. The relative levels of specific mRNAs were estimated by quantitative RT-PCR using specific reagents.

RESULTS

The FGF-2/HS- or TGF-β-induced activation of corneal stromal keratocytes to fibroblast- or myofibroblast-phenotype, respectively, resulted in marked decreases in cell surface-associated and secreted keratan sulfate proteoglycans (KSPGs). Both keratocan and lumican proteins and their mRNAs were downregulated in the activated keratocytes. However, JNK inhibition during the activation of keratocytes, pretreated with the JNK inhibitor, suppressed the reduction in the cell-surface associated and secreted KSPGs (lumican and keratocan), and their mRNA transcripts. Downregulation of total KSPGs and their mRNAs was also inhibited by decreasing JNK1 and JNK2 levels via JNK1/2 DsiRNA transfection of keratocytes before their activation.

CONCLUSIONS

Extrapolating from the present study, FGF-2- and TGF-β1-activation of JNK signaling pathway may be partly responsible for the downregulation of keratocan and lumican expression in activated corneal keratocytes observed during corneal stromal wound healing.

The role of RhoA/Rho kinase pathway in endothelial dysfunction

Endothelial dysfunction is a key event in the development of vascular disease, and it precedes clinically obvious vascular pathology. Abnormal activation of the RhoA/Rho kinase (ROCK) pathway has been found to elevate vascular tone through unbalancing the production of vasodilating and vasoconstricting substances. Inhibition of the RhoA/ROCK pathway can prevent endothelial dysfunction in a variety of pathological conditions. This review, based on recent molecular, cellular, and animal studies, focuses on the current understanding of the ROCK pathway and its roles in endothelial dysfunction.

MCP-1/CCR2B-dependent loop upregulates MUC5AC and MUC5B in human airway epithelium

Cigarette smoke represents a major risk factor for the development of chronic obstructive pulmonary disease (COPD), a respiratory condition associated with airflow obstruction, mucus hypersecretion, chronic inflammation, and upregulation of inflammatory mediators such as the monocyte chemotactic protein-1 (MCP-1). MCP-1 through its receptor CCR2 induces chemotaxis and activates (44/42)MAPK, a kinase known to play a key role in mucin regulation in bronchial epithelium. In the present study we used differentiated primary cultures of normal human bronchial epithelial (NHBE) cells to test whether MCP-1 through its receptor CCR2 induces mucin upregulation. We have provided evidence that NHBE cells release MCP-1 to the epithelial surface and express the CCR2B isoform of the receptor mainly at the apical pole. In addition, we found that MCP-1 has a novel function in airway epithelium, increasing the two major airway mucins MUC5AC and MUC5B, an effect mediated, at least in part, by a cascade of events initiated by interaction of its receptor CCR2B with G(q) subunits in caveolae, followed by PLCβ, PKC, and (44/42)MAPK activation. We also have shown that MCP-1 is able to induce its own expression using the same receptor but through a different pathway that involves RhoA GTPase. Furthermore, we found that a single exposure to MCP-1 is enough to induce MCP-1 secretion and sustained mucin upregulation up to 7 days after initial exposure, an effect mediated by CCR2B as confirmed using short hairpin RNA. These results agree with our data in smoker's airway epithelium, where CCR2B is present in MUC5AC- and MUC5B-expressing cells and augmented MCP-1 expression is associated with increased MUC5AC and MUC5B immunolabeling, suggesting that the mechanisms described in primary cell cultures in the present study are operative in vivo. Therefore, therapeutic approaches targeting MCP-1/CCR2B may be useful in preventing not only influx of inflammatory cells to the airways but also mucus hypersecretion and goblet cell hyperplasia.