Antifibrotic effects of noscapine through activation of prostaglandin E2 receptors and protein kinase A

Critical role of Gα12 and Gα13 proteins in TGF-β-induced myofibroblast differentiation

Myofibroblast differentiation, characterized by accumulation of cytoskeletal and extracellular matrix proteins by fibroblasts, is a key process in wound healing and pathogenesis of tissue fibrosis. Transforming growth factor-β (TGF-β) is the most powerful known driver of myofibroblast differentiation. TGF-β signals through transmembrane receptor serine/threonine kinases that phosphorylate Smad transcription factors (Smad2/3) leading to activation of transcription of target genes. Heterotrimeric G proteins mediate a distinct signaling from seven-transmembrane G protein coupled receptors, not commonly linked to Smad activation. We asked if G protein signaling plays any role in TGF-β-induced myofibroblast differentiation, using primary cultured human lung fibroblasts. Activation of Gαs by cholera toxin blocked TGF-β-induced myofibroblast differentiation without affecting Smad2/3 phosphorylation. Inhibition of Gαi by pertussis toxin, or siRNA-mediated combined knockdown of Gαq and Gα11 had no significant effect on TGF-β-induced myofibroblast differentiation. A combined knockdown of Gα12 and Gα13 resulted in a drastic inhibition of TGF-β-stimulated expression of myofibroblast marker proteins (collagen-1, fibronectin, smooth-muscle α-actin), with siGα12 being significantly more potent than siGα13. Mechanistically, a combined knockdown of Gα12 and Gα13 resulted in a substantially reduced phosphorylation of Smad2 and Smad3 in response to TGF-β, which was accompanied by a significant decrease in the expression of TGFβ receptors (TGFBR1, TGFBR2) and of Smad3 under siGα12/13 conditions. In conclusion, our study uncovers a novel role of Gα12/13 proteins in the control of TGF-β signaling and myofibroblast differentiation.

Evaluation of Anti-Nociceptive, Anti-Inflammatory, and Anti-Fibrotic effects of noscapine against a rat model of Achilles tendinopathy

During tendinopathy, prolonged inflammation results in fibrosis and the adherence of tendons to the adjacent tissues, causing discomfort and movement disorders. As a natural compound, noscapine has several anti-inflammatory and anti-fibrotic properties. Therefore, we aimed to investigate the effects of noscapine against a rat model of tendinopathy. We created a surgical rat model of Achilles tendon damage to emulate tendinopathy. Briefly, an incision was made on the Achilles tendon, and it was then sutured using an absorbable surgical thread. Immediately, the injured area was topically treated with the vehicle, noscapine (0.2, 0.6, and 1.8 mg/kg), or dexamethasone (0.1 mg/kg) as a positive control. During the 19-day follow-up period, animals were assessed for weight, behavior, pain, and motor coordination testing. On day 20th, the rats were sacrificed, and the tendon tissue was isolated for macroscopic scoring, microscopic (H&E, Masson's trichrome, Ki67, p53) analyses, and cytokine secretion levels. The levels of macroscopic parameters, including thermal hyperalgesia, mechanical and cold allodynia, deterioration of motor coordination, tendon adhesion score, and microscopic indices, namely histological adhesion, vascular prominence and angiogenesis, and Ki67 and p53 levels, as well as fibrotic and inflammatory biomarkers (IL-6, TNF-α, TGF-β, VEGF) were significantly increased in the vehicle group compared to the sham group (P < 0.05-0.001 for all cases). In contrast, the administration of noscapine (0.2, 0.6, and 1.8 mg/kg) attenuated the pain, fibrosis, and inflammatory indices in a dose-dependent manner compared to the vehicle group (P < 0.05-0.001). Histological research indicated that noscapine 0.6 and 1.8 mg/kg had the most remarkable healing effects. Interestingly, two higher doses of noscapine had impacts similar to those of the positive control group in both clinical and paraclinical assessments. Taken together, our findings suggested that noscapine could be a promising medicine for treating tendinopathies.

Noscapine alleviates unilateral ureteral obstruction-induced inflammation and fibrosis by regulating the TGFβ1/Smads signaling pathways

Renal fibrosis is a common pathway leading to progressive renal function loss in various forms of chronic kidney disease. Many fibrogenic factors regulate renal fibrosis; two key players are post-injury inflammation and transforming growth factor-β1 (TGF-β1)-induced myofibroblast differentiation. Myofibroblast differentiation is tightly regulated by the microtubule polymerization. Noscapine, an antitussive plant alkaloid, is a potent microtubule-interfering agent previously identified as a potential anticancer compound. Here, we examined how noscapine affects renal fibrogenesis in an in vitro renal fibroblast model and an in vivo unilateral ureteral obstruction (UUO) model. UUO mice were intraperitoneally treated with noscapine at 1 day before UUO surgery and daily thereafter. At 7 days post-surgery, kidneys were collected for further analysis. To analyze whether noscapine inhibits downstream TGF-β1-related signaling, we pre-incubated NRK-49F fibroblasts with noscapine and then performed TGF-β1 stimulation. In UUO mice, noscapine attenuated extracellular matrix protein deposition and the expression levels of type I collagen, type IV collagen, α-smooth muscle actin, and fibronectin. In addition, noscapine decreased tubulointerstitial inflammation in UUO kidneys by reducing TLR2 expression, modulating NLRP3 inflammasome activation, reducing macrophage infiltration, and antagonizing the M2 macrophage phenotype. Furthermore, noscapine pre-incubation suppressed the TGF-β1-induced fibroblast-myofibroblast transformation by downregulating the TGF-β/Smads signaling pathways in NRK-49F cells. These results suggest that noscapine reduces tubulointerstitial inflammation and fibrosis in the kidneys of UUO mice and inhibits the fibroblast-myofibroblast transformation induced by TGF-β1. Noscapine is an over-the-counter antitussive that has been used safely for several decades. Therefore, noscapine is an attractive therapeutic agent for inhibiting renal tubulointerstitial fibrosis.

Molecular mechanisms and targets of right ventricular fibrosis in pulmonary hypertension

Right ventricular fibrosis is a stress response, predominantly mediated by cardiac fibroblasts. This cell population is sensitive to increased levels of pro-inflammatory cytokines, pro-fibrotic growth factors and mechanical stimulation. Activation of fibroblasts results in the induction of various molecular signaling pathways, most notably the mitogen-activated protein kinase cassettes, leading to increased synthesis and remodeling of the extracellular matrix. While fibrosis confers structural protection in response to damage induced by ischemia or (pressure and volume) overload, it simultaneously contributes to increased myocardial stiffness and right ventricular dysfunction. Here, we review state-of-the-art knowledge of the development of right ventricular fibrosis in response to pressure overload and provide an overview of all published preclinical and clinical studies in which right ventricular fibrosis was targeted to improve cardiac function.

Inhibition of Myeloperoxidase Pro-Fibrotic Effect by Noscapine in Equine Endometrium

Myeloperoxidase is an enzyme released by neutrophils when neutrophil extracellular traps (NETs) are formed. Besides myeloperoxidase activity against pathogens, it was also linked to many diseases, including inflammatory and fibrotic ones. Endometrosis is a fibrotic disease of the mare endometrium, with a large impact on their fertility, where myeloperoxidase was shown to induce fibrosis. Noscapine is an alkaloid with a low toxicity, that has been studied as an anti-cancer drug, and more recently as an anti-fibrotic molecule. This work aims to evaluate noscapine inhibition of collagen type 1 (COL1) induced by myeloperoxidase in equine endometrial explants from follicular and mid-luteal phases, at 24 and 48 h of treatment. The transcription of collagen type 1 alpha 2 chain (COL1A2), and COL1 protein relative abundance were evaluated by qPCR and Western blot, respectively. The treatment with myeloperoxidase increased COL1A2 mRNA transcription and COL1 protein, whereas noscapine was able to reduce this effect with respect to COL1A2 mRNA transcription, in a time/estrous cycle phase-dependent manner (in explants from the follicular phase, at 24 h of treatment). Our study indicates that noscapine is a promising drug to be considered as an anti-fibrotic molecule to prevent endometrosis development, making noscapine a strong candidate to be applied in future endometrosis therapies.

The role of PGE2 and EP receptors on lung's immune and structural cells; possibilities for future asthma therapy

Asthma is the most common airway chronic disease with treatments aimed mainly to control the symptoms. Adrenergic receptor agonists, corticosteroids and anti-leukotrienes have been used for decades, and the development of more targeted asthma treatments, known as biological therapies, were only recently established. However, due to the complexity of asthma and the limited efficacy as well as the side effects of available treatments, there is an urgent need for a new generation of asthma therapies. The anti-inflammatory and bronchodilatory effects of prostaglandin E2 in asthma are promising, yet complicated by undesirable side effects, such as cough and airway irritation. In this review, we summarize the most important literature on the role of all four E prostanoid (EP) receptors on the lung's immune and structural cells to further dissect the relevance of EP2/EP4 receptors as potential targets for future asthma therapy.

CYSTEINE-RICH DOMAIN OF TYPE III COLLAGEN N-PROPEPTIDE INHIBITS FIBROBLAST ACTIVATION BY ATTENUATING TGFβ SIGNALING

TGFβ is a key regulator of the dynamic reciprocity between cells and the extracellular matrix that drives physiologic and pathologic responses in both tissue repair and tumor microenvironments. Our studies define type III Collagen (Col3) as a suppressor of scar formation and desmoplasia through its effects, in part, on myofibroblasts. TGFβ stimulates activation of myofibroblasts, and here, we demonstrate that cultured Col3-deficient fibroblasts have increased TGFβ signaling compared to wild-type fibroblasts. Moreover, kinetic binding studies show that a synthetic peptide containing a Col3 cysteine-rich (CR) domain found within its N-propeptide binds in a dose-dependent manner to TGFβ1, while a CR control peptide with mutated cysteines does not, suggesting that Col3 attenuates TGFβ signaling in part through the N-propeptide CR domain. Consistent with this hypothesis, the CR peptide attenuates TGFβ signaling in fibroblasts and 4T1 breast cancer cells and suppresses fibroblast activation and contraction, as assessed by α-smooth-muscle actin staining, cell wrinkling of deformable silicone, and stressed-fibroblast populated collagen lattice contraction assays. Finally, CR peptide treatment of orthotopically injected breast cancer cells (4T1) suppresses intratumoral fibroblast activation and inhibits primary tumor growth compared to CR control. Treatment with the CR peptide decreases both intratumoral canonical and non-canonical downstream TGFβ signaling targets, consistent with its extracellular binding to TGFβ. Taken together, our results suggest that the Col3 N-propeptide CR domain binds TGFβ1 and attenuates (but importantly does not eliminate) TGFβ signaling in fibroblasts and cancer cells. Expanding on our previous work, this study demonstrates an additional mechanism by which Col3 regulates cell behaviors in post-injury and tumor microenvironments and suggests that novel Col3-targeted strategies could effectively control biologic responses in vivo and improve anti-scarring/fibrosis and oncologic therapies.

The Inhibitory Effect of Noscapine on the In Vitro Cathepsin G-Induced Collagen Expression in Equine Endometrium

Cathepsin G (CAT) is a protease released by neutrophils when forming neutrophil extracellular traps that was already associated with inducing type I collagen (COL1) in equine endometrium in vitro. Endometrosis is a fibrotic condition mainly characterized by COL1 deposition in the equine endometrium. The objective was to evaluate if noscapine (an alkaloid for cough treatment with anti-neoplastic and anti-fibrotic properties) would reduce COL1A2 transcription (evaluated by qPCR) and COL1 protein relative abundance (evaluated by western blot) induced by CAT in equine endometrial explants from follicular and mid-luteal phases treated for 24 or 48 h. The explants treated with CAT increased COL1 expression. Noscapine decreased COL1A2 transcription at both estrous cycle phases, but COL1 relative protein only at the follicular phase, both induced by CAT. Additionally, the noscapine anti-fibrotic action was found to be more effective in the follicular phase. The CAT treatment caused more fibrosis at the longest period of treatment, while noscapine acted better at the shortest time of treatment. Our results showed that noscapine could act as an anti-fibrotic drug in equine endometrosis by inhibiting CAT in vitro. Noscapine offers a new promising therapeutic tool for treating fibrosis as a single non-selective agent to be considered in the future.

9-Ethynyl noscapine induces G2/M arrest and apoptosis by disrupting tubulin polymerization in cervical cancer

Noscapine is a phthalide isoquinoline alkaloid present in the latex of Papaver somniferum and has demonstrated potent antitumor activity in various cancer models. Structural changes in the core molecule of noscapine architecture have produced a number of potent analogs. We have recently synthesized the novel noscapine analogs (3, 4, and 5) with different functional groups appended at ninth position of natural noscapine. The anticancer activity of these compounds has been investigated using various human cancer cell lines such as HeLa (cervical cancer), DU-145 (prostate cancer), MCF-7 (breast cancer), and IMR-32 (neuroblastoma). One of the compounds in this series, 9-ethynyl noscapine (5), has demonstrated good anticancer activity against HeLa cells. Biological studies demonstrated that compound 5 decreased cell viability and colony formation in HeLa cells in a concentration dependent manner. To further uncover the mechanism in detail, we evaluated compound 5 effect on cell cycle progression, microtubule dynamics, and apoptosis. Cell cycle and western blotting analysis revealed that 9-ethynyl noscapine treatment resulted in cell cycle arrest at G2/M and decreased CDK1 and cyclinB1 protein expression. We also observed that 9-ethynyl noscapine (5) treatment leads to disruption in tubulin polymerization and induction of apoptosis by decreasing expression of bcl2, pro-caspase 3, and activation of cytochrome C. Taken together, our results indicate that 9-ethynyl noscapine (5) effectively supresses the growth of cervical cancer cells (HeLa) by disrupting tubulin polymerization, cell cycle progression leading to apoptosis.

Expression of serum response factor in the lung mesenchyme is essential for development of pulmonary fibrosis

Extracellular matrix deposition characterizes idiopathic pulmonary fibrosis (IPF) and is orchestrated by myofibroblasts. The lung mesenchyme is an essential source of myofibroblasts in pulmonary fibrosis. Although the transcription factor serum response factor (SRF) has shown to be critical in the process of myofibroblast differentiation, its role in development of pulmonary fibrosis has not been determined in vivo. In this study, we observed that SRF expression localized to mesenchymal compartments, areas of dense fibrosis, and fibroblastic foci in human (IPF and normal) and bleomycin-treated mouse lungs. To determine the role of mesenchymal SRF in pulmonary fibrosis, we utilized a doxycycline-inducible, Tbx4 lung enhancer (Tbx4^LE)-driven Cre-recombinase to disrupt SRF expression in the lung mesenchyme in vivo. Doxycycline-treated Tbx4^LE-rtTA/TetO-Cre/tdTom/SRF^f,f (and controls) were treated with a single intratracheal dose of bleomycin to induce pulmonary fibrosis and examined for lung mesenchymal expansion, pulmonary fibrosis, and inflammatory response. Bleomycin-treated Tbx4^LE-rtTA/TetO-Cre/tdTom/SRF^f,f mice showed decreased numbers of Tbx4^LE-positive lung mesenchymal cells (LMCs) and collagen accumulation (via hydroxyproline assay) compared with controls. This effect was associated with SRF-null LMCs losing their proliferative and myofibroblast differentiation potential compared with SRF-positive controls. Together, these data demonstrate that SRF plays a critical role in LMC myofibroblast expansion during bleomycin-induced pulmonary fibrosis. This sets the stage for pharmacological strategies that specifically target SRF in the lung mesenchyme as a potential means of treating pulmonary fibrosis.

Noscapine Acts as a Protease Inhibitor of In Vitro Elastase-Induced Collagen Deposition in Equine Endometrium

Endometrosis is a reproductive pathology that is responsible for mare infertility. Our recent studies have focused on the involvement of neutrophil extracellular traps enzymes, such as elastase (ELA), in the development of equine endometrosis. Noscapine (NOSC) is an alkaloid derived from poppy opium with anticough, antistroke, anticancer, and antifibrotic properties. The present work investigates the putative inhibitory in vitro effect of NOSC on collagen type I alpha 2 chain (COL1A2) mRNA and COL1 protein relative abundance induced by ELA in endometrial explants of mares in the follicular or mid-luteal phases at 24 or 48 h of treatment. The COL1A2 mRNA was evaluated by qPCR and COL1 protein relative abundance by Western blot. In equine endometrial explants, ELA increased COL 1 expression, while NOSC inhibited it at both estrous cycle phases and treatment times. These findings contribute to the future development of new endometrosis treatment approaches. Noscapine could be a drug capable of preventing collagen synthesis in mare’s endometrium and facilitate the therapeutic approach.

Antibacterial activity of noscapine analogs

The antibacterial properties of close noscapine analogs have not been previously reported. We used our pDualrep2 double-reporter High Throughput Screening (HTS) platform to identify a series of noscapine derivatives with promising antibacterial activity. The platform is based on RPF (SOS-response/DNA damage) and Katushka2S (inhibition of translation) proteins and simultaneously provides information on antibacterial activity and the mechanism of action of small-molecule compounds against E. coli. The most potent compound exhibited an MIC of 13.5 µM(6.25 µg/ml) and a relatively low cytotoxicity against HEK293 cells (CC₅₀ = 71 µM, selectivity index: ~5.5). Some compounds from this series induced average Katushka2S reporter signals, indicating inhibition of translation machinery in the bacteria; however, these compounds did not attenuate translation in vitro in a luciferase-based translation assay. The most effective compounds did not significantly arrest the mitotic cycle in HEK293 cells, in contrast to the parent compound in a flow cytometry assay. Several molecules showed activity against clinically relevant gram-negative and gram-positive bacterial strains. Compounds from the discovered series can be reasonably regarded as good templates for further development and evaluation.

International Union of Basic and Clinical Pharmacology. CIX. Differences and Similarities between Human and Rodent Prostaglandin E2 Receptors (EP1-4) and Prostacyclin Receptor (IP): Specific Roles in Pathophysiologic Conditions

Prostaglandins are derived from arachidonic acid metabolism through cyclooxygenase activities. Among prostaglandins (PGs), prostacyclin (PGI2) and PGE2 are strongly involved in the regulation of homeostasis and main physiologic functions. In addition, the synthesis of these two prostaglandins is significantly increased during inflammation. PGI2 and PGE2 exert their biologic actions by binding to their respective receptors, namely prostacyclin receptor (IP) and prostaglandin E2 receptor (EP) 1-4, which belong to the family of G-protein-coupled receptors. IP and EP1-4 receptors are widely distributed in the body and thus play various physiologic and pathophysiologic roles. In this review, we discuss the recent advances in studies using pharmacological approaches, genetically modified animals, and genome-wide association studies regarding the roles of IP and EP1-4 receptors in the immune, cardiovascular, nervous, gastrointestinal, respiratory, genitourinary, and musculoskeletal systems. In particular, we highlight similarities and differences between human and rodents in terms of the specific roles of IP and EP1-4 receptors and their downstream signaling pathways, functions, and activities for each biologic system. We also highlight the potential novel therapeutic benefit of targeting IP and EP1-4 receptors in several diseases based on the scientific advances, animal models, and human studies. SIGNIFICANCE STATEMENT: In this review, we present an update of the pathophysiologic role of the prostacyclin receptor, prostaglandin E2 receptor (EP) 1, EP2, EP3, and EP4 receptors when activated by the two main prostaglandins, namely prostacyclin and prostaglandin E2, produced during inflammatory conditions in human and rodents. In addition, this comparison of the published results in each tissue and/or pathology should facilitate the choice of the most appropriate model for the future studies.

Neutrophils, monocytes and other immune components in the equine endometrium: Friends or foes?

The innate and adaptive immune mechanisms are key components of regulation of reproductive physiological function and uterine disorders in equine uterus. The predominant immunological response in equine endometrium, characterized by an innate immune response, occurs under estrogens influence, in the follicular phase. Although, the increase in immune-related genes in equine endometrium during estrus has been suggested to play a role in uterine clearance after mating, immune cells and their product, i.e. cytokines play also mandatory role in the luteal development and maintenance, regression of equine corpus luteum, as well as in early pregnancy. Innate immune response is nonspecific and acts as the first line of defense against pathogens, foreign stimuli that include constituents of seminal fluid and local infections (endometritis). It has been recently established that a phagocytosis-independent mechanism to restrain bacteria, by means of neutrophil extracellular traps (NETs) formation, is involved in pathogenesis of in mare endometrial fibrosis (endometrosis). Moreover, persistent macrophages and mast cell activation could also have pro-fibrotic roles by secreting great amounts of pro-fibrotic factors and lead to fibrosis. This review will highlight the involvement of immune key components of the innate and adaptive immune system and their products in equine uterus and their contribution to reproductive physiological function and uterine disorders.

Deficiency of CRTH2, a Prostaglandin D2 Receptor, Aggravates Bleomycin-induced Pulmonary Inflammation and Fibrosis

Chemoattractant receptor homologous with T-helper cell type 2 cells (CRTH2), a receptor for prostaglandin D₂, is preferentially expressed on T-helper cell type 2 lymphocytes, group 2 innate lymphoid cells, eosinophils, and basophils, and elicits the production of type 2 cytokines, including profibrotic IL-13. We hypothesized that lack of CRTH2 might protect against fibrotic lung disease, and we tested this hypothesis using a bleomycin-induced lung inflammation and fibrosis model in CRTH2-deficient (CRTH2^-/-) or wild-type BALB/c mice. Compared with wild-type mice, CRTH2^-/- mice treated with bleomycin exhibited significantly higher mortality, enhanced accumulation of inflammatory cells 14-21 days after bleomycin injection, reduced pulmonary compliance, and increased levels of collagen and total protein in the lungs. These phenotypes were associated with decreased levels of IFN-γ, IL-6, IL-10, and IL-17A in BAL fluid. Adoptive transfer of splenocytes from wild-type, but not CRTH2^-/-, mice 2 days before injection of bleomycin resolved the sustained inflammation as well as the increased collagen and protein accumulation in the lungs of CRTH2^-/- mice. We consider that the disease model is driven by γδT cells that express CRTH2; thus, the adoptive transfer of γδT cells could ameliorate bleomycin-induced alveolar inflammation and fibrosis.

The Role of Airway Myofibroblasts in Asthma

Airway remodeling is a characteristic feature of asthma and is thought to play an important role in the pathogenesis of airway hyperresponsiveness. Myofibroblasts are key structural cells involved in injury and repair, and there is evidence that dysregulation of their normal function contributes to airway remodeling. Despite the importance of myofibroblasts, a lack of specific cellular markers and inconsistent nomenclature have limited recognition of their key role in airway remodeling. Myofibroblasts are increased several-fold in the airways in asthma, in proportion to the severity of the disease. Myofibroblasts are postulated to be derived from both tissue-resident and bone marrow-derived cells, depending on the stage of injury and the tissue. A small number of studies have demonstrated attenuation of myofibroblast numbers and also reversal of established myofibroblast populations in asthma and other inflammatory processes. In this article, we review what is currently known about the biology of myofibroblasts in the airways in asthma and identify potential targets to reduce or reverse the remodeling process. However, further translational research is required to better understand the mechanistic role of the myofibroblast in asthma.

Impairment of the antifibrotic prostaglandin E2 pathway may influence neutrophil extracellular traps-induced fibrosis in the mare endometrium

Prostaglandin E₂ (PGE₂) has contradictory effects in many organs. It may have proinflammatory, anti-inflammatory, or anti-fibrotic roles, depending on the type of receptors to which it binds. By signaling through its receptors EP2 and EP4, PGE₂ mediates anti-inflammatory and anti-fibrotic actions. In spite of chronic endometrial fibrosis (endometrosis) being a major cause of mare infertility, its pathogenesis is not fully understood. We have shown that contact of mare endometrium in vitro with neutrophil extracellular traps (NETs) proteases favors endometrial collagen type I production. Therefore, we investigated the involvement of the PGE₂ pathway in collagen deposition in mare endometrium, challenged in vitro with proteases present in NETs. Mare endometria (Kenney and Doig categories I/IIA and IIB/III), obtained in the follicular phase (FLP) and mid-luteal phase (MLP), were incubated for 24 h with components found in NETs (elastase, cathepsin-G, and myeloperoxidase). Secretion of PGE₂ and transcripts for specific PGE synthase (PGES) and PGE₂ receptors (EP2 and EP4) were evaluated. Impaired PGE₂ production and low EP2 transcript abundance depended on the endometrial category and estrous cycle phase. Impairment of PGE₂ and/or EP2 might play a role in FLP (category IIB/III) and MLP (I/IIA) endometrial fibrogenesis because of the reduction in its antifibrotic capacity. In conclusion, priming of the endometrium with endogenous ovarian steroids might inhibit the antifibrotic PGE₂ pathway either in healthy or pathologic tissues with collagen formation after NETs proteases action.

Prostaglandin E2 inhibits profibrotic function of human pulmonary fibroblasts by disrupting Ca2+ signaling

We have shown that calcium (Ca²⁺) oscillations in human pulmonary fibroblasts (HPFs) contribute to profibrotic effects of transforming growth factor-β (TGF-β) and that disruption of these oscillations blunts features of pulmonary fibrosis. Prostaglandin E₂ (PGE₂) exerts antifibrotic effects in the lung, but the mechanisms for this action are not well defined. We thus sought to explore interactions between PGE₂ and the profibrotic agent TGF-β in pulmonary fibroblasts (PFs) isolated from patients with or without idiopathic pulmonary fibrosis (IPF). PGE₂ inhibited TGF-β-promoted [Ca²⁺] oscillations and prevented the activation of Akt and Ca²⁺/calmodulin-dependent protein kinase-II (CaMK-II) but did not prevent activation of Smad-2 or ERK. PGE₂ also eliminated TGF-β-stimulated expression of collagen A1, fibronectin, and α-smooth muscle actin and reduced stress fiber formation in the HPFs. RNA sequencing revealed that HPFs preferentially express EP₂ receptors relative to other prostanoid receptor subtypes: EP₂ expression is ~10-fold higher than that of EP₄ receptors; EP₁ and EP₃ receptors are barely detectable; and EP₂-receptor expression is ~3.5-fold lower in PFs from IPF patients than in normal HPFs. The inhibitory effects of PGE₂ on synthetic function and stress fiber formation were blocked by selective EP₂ or EP₄ antagonists and mimicked by selective EP₂ or EP₄ agonists, the phosphodiesterase inhibitor isobutylmethylxanthine and forskolin, all of which elevate cellular cAMP concentrations. We conclude that PGE₂, likely predominantly via EP₂ receptors, interferes with Ca²⁺ signaling, CaMK-II activation, and Akt activation in IPF-HPFs and HPFs treated with TGF-β. Moreover, a decreased expression of EP₂ receptors in pulmonary fibroblasts from IPF patients may contribute to the pathophysiology of this disease.

Inhibition of Phosphoglycerate Dehydrogenase Attenuates Bleomycin-induced Pulmonary Fibrosis

Organ fibrosis, including idiopathic pulmonary fibrosis, is associated with significant morbidity and mortality. Because currently available therapies have limited effect, there is a need to better understand the mechanisms by which organ fibrosis occurs. We have recently reported that transforming growth factor (TGF)-β, a key cytokine that promotes fibrogenesis, induces the expression of the enzymes of the de novo serine and glycine synthesis pathway in human lung fibroblasts, and that phosphoglycerate dehydrogenase (PHGDH; the first and rate-limiting enzyme of the pathway) is required to promote collagen protein synthesis downstream of TGF-β. In this study, we investigated whether inhibition of de novo serine and glycine synthesis attenuates lung fibrosis in vivo. We found that TGF-β induces mRNA and protein expression of PHGDH in murine fibroblasts. Similarly, intratracheal administration of bleomycin resulted in increased expression of PHGDH in mouse lungs, localized to fibrotic regions. Using a newly developed small molecule inhibitor of PHGDH (NCT-503), we tested whether pharmacologic inhibition of PHGDH could inhibit fibrogenesis both in vitro and in vivo. Treatment of murine and human lung fibroblasts with NCT-503 decreased TGF-β-induced collagen protein synthesis. Mice treated with the PHGDH inhibitor beginning 7 days after intratracheal instillation of bleomycin had attenuation of lung fibrosis. These results indicate that the de novo serine and glycine synthesis pathway is necessary for TGF-β-induced collagen synthesis and bleomycin-induced pulmonary fibrosis. PHGDH and other enzymes in the de novo serine and glycine synthesis pathway may be a therapeutic target for treatment of fibrotic diseases, including idiopathic pulmonary fibrosis.

Reversal of drug-resistance by noscapine chemo-sensitization in docetaxel resistant triple negative breast cancer

Multidrug resistance (MDR) is a major impediment to cancer treatment. Here, for the first time, we investigated the chemo-sensitizing effect of Noscapine (Nos) at low concentrations in conjunction with docetaxel (DTX) to overcome drug resistance of triple negative breast cancer (TNBC). In vitro experiments showed that Nos significantly inhibited proliferation of TNBC wild type (p < 0.01) and drug resistant (p < 0.05) TNBC cells. Nos followed by DTX treatment notably increased the cell viability (~1.3 fold) markedly (p < 0.05) in 3D models compared to conventional 2D systems. In vivo oral administration of Nos (100 mg/kg) followed by intravenous DTX (5 mg/kg) liposome treatment revealed regression of xenograft tumors in both wild type (p < 0.001) and drug-resistant (p < 0.05) xenografts. In wild type xenografts, combination of Nos plus DTX group showed 5.49 and 3.25 fold reduction in tumor volume compared to Nos and DTX alone groups, respectively. In drug-resistant xenografts, tumor volume was decreased 2.33 and 1.41 fold in xenografts treated with Nos plus DTX significantly (p < 0.05) compared to Nos and DTX alone respectively and downregulated the expression of anti-apoptotic factors and multidrug resistance proteins. Collectively, chemo-sensitizing effect of Nos followed by DTX regime provide a promising chemotherapeutic strategy and its significant role for the treatment of drug-resistant TNBC.

Dibutyryl-cAMP attenuates pulmonary fibrosis by blocking myofibroblast differentiation via PKA/CREB/CBP signaling in rats with silicosis

BACKGROUND

Myofibroblasts play a major role in the synthesis of extracellular matrix (ECM) and the stimulation of these cells is thought to play an important role in the development of silicosis. The present study was undertaken to investigate the anti-fibrotic effects of dibutyryl-cAMP (db-cAMP) on rats induced by silica.

METHODS

A HOPE MED 8050 exposure control apparatus was used to create the silicosis model. Rats were randomly divided into 4 groups: 1)controls for 16 w; 2)silicosis for 16 w; 3)db-cAMP pre-treatment; 4) db-cAMP post-treatment. Rat pulmonary fibroblasts were cultured in vitro and divided into 4 groups as follows: 1) controls; 2) 10^-7mol/L angiotensin II (Ang II); 3) Ang II +10^-4 mol/L db-cAMP; and 4) Ang II + db-cAMP+ 10^-6 mol/L H89. Hematoxylin-eosin (HE), Van Gieson staining and immunohistochemistry (IHC) were performed to observe the histomorphology of lung tissue. The levels of cAMP were detected by enzyme immunoassay. Double-labeling for α-SMA with Gαi3, protein kinase A (PKA), phosphorylated cAMP-response element-binding protein (p-CREB), and p-Smad2/3 was identified by immunofluorescence staining. Protein levels were detected by Western blot analysis. The interaction between CREB-binding protein (CBP) and Smad2/3 and p-CREB were measured by co-immunoprecipitation (Co-IP).

RESULTS

Db-cAMP treatment reduced the number and size of silicosis nodules, inhibited myofibroblast differentiation, and extracellular matrix deposition in vitro and in vivo. In addition, db-cAMP regulated Gαs protein and inhibited expression of Gαi protein, which increased endogenous cAMP. Db-cAMP increased phosphorylated cAMP-response element-binding protein (p-CREB) via protein kinase A (PKA) signaling, and decreased nuclear p-Smad2/3 binding with CREB binding protein (CBP), which reduced activation of p-Smads in fibroblasts induced by Ang II.

CONCLUSIONS

This study showed an anti-silicotic effect of db-cAMP that was mediated via PKA/p-CREB/CBP signaling. Furthermore, the findings offer novel insight into the potential use of cAMP signaling for therapeutic strategies to treat silicosis.

Myofibroblast repair mechanisms post-inflammatory response: a fibrotic perspective

INTRODUCTION

Fibrosis is a complex chronic disease characterized by a persistent repair response. Its pathogenesis is poorly understood but it is typically the result of chronic inflammation and maintained with the required activity of transforming growth factor-β (TGFβ) and extracellular matrix (ECM) tension, both of which drive fibroblasts to transition into a myofibroblast phenotype.

FINDINGS

As the effector cells of repair, myofibroblasts migrate to the site of injury to deposit excessive amounts of matrix proteins and stimulate high levels of contraction. Myofibroblast activity is a decisive factor in whether a tissue is properly repaired by controlled wound healing or rendered fibrotic by deregulated repair. Extensive studies have documented the various contributing factors to an abrogated repair response. Though these fibrotic factors are known, very little is understood about the opposing antifibrotic molecules that assist in a successful repair, such as prostaglandin E2 (PGE₂) and ECM retraction. The following review will discuss the general development of fibrosis through the transformation of myofibroblasts, focusing primarily on the prominent profibrotic pathways of TGFβ and ECM tension and antifibrotic pathways of PGE₂ and ECM retraction.

CONCLUSIONS

The idea is to understand the ways in which the cell, after an injury and inflammatory response, normally controls its repair mechanisms through its homeostatic regulators so as to mimic them therapeutically to control abnormal pathways.

Downregulation of TGF-β Receptor-2 Expression and Signaling through Inhibition of Na/K-ATPase

Transforming growth factor-beta (TGF-β) is a multi-functional cytokine implicated in the control of cell growth and differentiation. TGF-β signals through a complex of TGF-β receptors 1 and 2 (TGFβR1 and TGFβR2) that phosphorylate and activate Smad2/3 transcription factors driving transcription of the Smad-target genes. The Na+/K+-ATPase is an integral plasma membrane protein critical for maintaining the electro-chemical gradient of Na+ and K+ in the cell. We found that inhibition of the Na+/K+ ATPase by ouabain results in a dramatic decrease in the expression of TGFβR2 in human lung fibrobalsts (HLF) at the mRNA and protein levels. This was accompanied by inhibition of TGF-β-induced Smad phosphorylation and the expression of TGF-β target genes, such as fibronectin and smooth muscle alpha-actin. Inhibition of Na+/K+ ATPase by an alternative approach (removal of extracellular potassium) had a similar effect in HLF. Finally, treatment of lung alveolar epithelial cells (A549) with ouabain also resulted in the downregulation of TGFβR2, the inhibition of TGF-β-induced Smad phosphorylation and of the expression of mesenchymal markers, vimentin and fibronectin. Together, these data demonstrate a critical role of Na+/K+-ATPase in the control of TGFβR2 expression, TGF-β signaling and cell responses to TGF-β.

An EP4 Receptor Agonist Inhibits Cardiac Fibrosis Through Activation of PKA Signaling in Hypertrophied Heart

Cardiac fibrosis is a pathological feature of myocardium of failing heart and plays causative roles in arrhythmia and cardiac dysfunction, but its regulatory mechanisms remain largely elusive. In this study, we investigated the effects of the novel EP4 receptor agonist ONO-0260164 on cardiac fibrosis in hypertrophied heart and explored the regulatory mechanisms in cardiac fibroblasts.In a mouse model of cardiac hypertrophy generated by transverse aortic constriction (TAC), ONO-0260164 treatment significantly prevented systolic dysfunction and progression of myocardial fibrosis at 5 weeks after TAC. In cultured neonatal rat cardiac fibroblasts, transforming growth factor-β1 (TGF-β1) induced upregulation of collagen type 1, alpha 1 (Col1a1) and type 3, alpha 1 (Col3a1), which was inhibited by ONO-0260164 treatment. ONO-0260164 activated protein kinase A (PKA) in the presence of TGF-β1 in the cardiac fibroblasts. PKA activation suppressed an increase in collagen expression induced by TGF-β1, indicating the important inhibitory roles of PKA activation in TGF-β1mediated collagen induction.We have demonstrated for the first time the antifibrotic effects of the novel EP4 agonist ONO-0260164 in vivo and in vitro, and the important role of PKA activation in the effects.

SIRT3 blocks myofibroblast differentiation and pulmonary fibrosis by preventing mitochondrial DNA damage

Myofibroblast differentiation is a key process in the pathogenesis of fibrotic diseases. Transforming growth factor-β₁ (TGF-β₁) is a powerful inducer of myofibroblast differentiation and is implicated in pathogenesis of tissue fibrosis. This study was undertaken to determine the role of mitochondrial deacetylase SIRT3 in TGF-β₁-induced myofibroblast differentiation in vitro and lung fibrosis in vivo. Treatment of human lung fibroblasts with TGF-β₁ resulted in increased expression of fibrosis markers, smooth muscle α-actin (α-SMA), collagen-1, and fibronectin. TGF-β₁ treatment also caused depletion of endogenous SIRT3, which paralleled with increased production of reactive oxygen species (ROS), DNA damage, and subsequent reduction in levels of 8-oxoguanine DNA glycosylase (OGG1), an enzyme that hydrolyzes oxidized guanine (8-oxo-dG) and thus protects DNA from oxidative damage. Overexpression of SIRT3 by adenovirus-mediated transduction reversed the effects of TGF-β₁ on ROS production and mitochondrial DNA damage and inhibited TGF-β₁-induced myofibroblast differentiation. To determine the antifibrotic role of SIRT3 in vivo, we used the bleomycin-induced mouse model of pulmonary fibrosis. Compared with wild-type controls, Sirt3-knockout mice showed exacerbated fibrosis after intratracheal instillation of bleomycin. Increased lung fibrosis was associated with decreased levels of OGG1 and concomitant accumulation of 8-oxo-dG and increased mitochondrial DNA damage. In contrast, the transgenic mice with whole body Sirt3 overexpression were protected from bleomycin-induced mtDNA damage and development of lung fibrosis. These data demonstrate a critical role of SIRT3 in the control of myofibroblast differentiation and lung fibrosis.

Noscapine chemosensitization enhances docetaxel anticancer activity and nanocarrier uptake in triple negative breast cancer

Chemosensitization and enhanced delivery to solid tumor are widely explored strategies to augment the anticancer efficacy of existing chemotherapeutics agents. The aim of current research was to investigate the role of low dose Noscapine (Nos) in potentiating docetaxel cytotoxicity and enhancing tumor penetration of nanocarriers. The objectives are; (1) To evaluate the chemo-sensitizing effect of Nos in combination with docetaxel (DTX), and to elucidate the possible mechanism (2) To investigate the effect of low dose Nos on tumor stroma and enhancing nanocarrier uptake in triple negative breast cancer (TNBC) bearing nude mice. Cytotoxicity and flow cytometry analysis of DTX in Nos (4µM) pre-treated MDA-MB-231 cells showed 3.0-fold increase in cell killing and 30% increase in number of late apoptotic cells, respectively. Stress transducer p38 phosphorylation was significantly upregulated with Nos exposure. DTX showed remarkable downregulation in expression of bcl-2, survivin and pAKT in Nos pre-treated MDA-MB-231 cells. Nos pre-sensitization significantly (p<0.02) enhanced the anti-migration effect of DTX. In vivo studies in orthotopic TNBC tumor bearing mice showed marked reduction in tumor collagen-I levels and significantly (p<0.03) higher intra-tumoral uptake of coumarin-6 loaded PEGylated liposomes (7-fold) in Nos treated group. Chemo-sensitization and anti-fibrotic effect of Nos could be a promising approach to increase anticancer efficacy of DTX which can be used for other nanomedicinal products.

Regulation of myofibroblast differentiation by cardiac glycosides

Myofibroblast differentiation is a key process in pathogenesis of fibrotic diseases. Cardiac glycosides (ouabain, digoxin) inhibit Na(+)-K(+)-ATPase, resulting in increased intracellular [Na(+)]-to-[K(+)] ratio in cells. Microarray analysis suggested that increased intracellular [Na(+)]/[K(+)] ratio may promote the expression of cyclooxygenase-2 (COX-2), a critical enzyme in the synthesis of prostaglandins. Given antifibrotic effects of prostaglandins through activation of protein kinase A (PKA), we examined if cardiac glycosides stimulate COX-2 expression in human lung fibroblasts and how they affect myofibroblast differentiation. Ouabain stimulated a profound COX-2 expression and a sustained PKA activation, which was blocked by COX-2 inhibitor or by COX-2 knockdown. Ouabain-induced COX-2 expression and PKA activation were abolished by the inhibitor of the Na(+)/Ca(2+) exchanger, KB-R4943. Ouabain inhibited transforming growth factor-β (TGF-β)-induced Rho activation, stress fiber formation, serum response factor activation, and the expression of smooth muscle α-actin, collagen-1, and fibronectin. These effects were recapitulated by an increase in intracellular [Na(+)]/[K(+)] ratio through the treatment of cells with K(+)-free medium or with digoxin. Although inhibition of COX-2 or of the Na(+)/Ca(2+) exchanger blocked ouabain-induced PKA activation, this failed to reverse the inhibition of TGF-β-induced Rho activation or myofibroblast differentiation by ouabain. Together, these data demonstrate that ouabain, through the increase in intracellular [Na(+)]/[K(+)] ratio, drives the induction of COX-2 expression and PKA activation, which is accompanied by a decreased Rho activation and myofibroblast differentiation in response to TGF-β. However, COX-2 expression and PKA activation are not sufficient for inhibition of the fibrotic effects of TGF-β by ouabain, suggesting that additional mechanisms must exist.

The Noscapine Chronicle: A Pharmaco-Historic Biography of the Opiate Alkaloid Family and its Clinical Applications

Given its manifold potential therapeutic applications and amenability to modification, noscapine is a veritable "Renaissance drug" worthy of commemoration. Perhaps the only facet of noscapine's profile more astounding than its versatility is its virtual lack of side effects and addictive properties, which distinguishes it from other denizens of Papaver somniferum. This review intimately chronicles the rich intellectual and pharmacological history behind the noscapine family of compounds, the length of whose arms was revealed over decades of patient scholarship and experimentation. We discuss the intriguing story of this family of nontoxic alkaloids, from noscapine's purification from opium at the turn of the 19th century in Paris to the recent torrent of rationally designed analogs with tremendous anticancer potential. In between, noscapine's unique pharmacology; impact on cellular signaling pathways, the mitotic spindle, and centrosome clustering; use as an antimalarial drug and cough suppressant; and exceptional potential as a treatment for polycystic ovarian syndrome, strokes, and diverse malignancies are catalogued. Seminal experiments involving some of its more promising analogs, such as amino-noscapine, 9-nitronoscapine, 9-bromonoscapine, and reduced bromonoscapine, are also detailed. Finally, the bright future of these oftentimes even more exceptional derivatives is described, rounding out a portrait of a truly remarkable family of compounds.

Megakaryoblastic leukemia-1 is required for the development of bleomycin-induced pulmonary fibrosis

BACKGROUND

Fibrosing disorders of the lung, such as idiopathic pulmonary fibrosis, are characterized by progressive extracellular matrix accumulation that is driven by myofibroblasts. The transcription factor megakaryoblastic leukemia-1 (MKL1) mediates myofibroblast differentiation in response to several profibrotic stimuli, but the role it plays in mediating pulmonary fibrosis has not been fully elucidated. In this study, we utilized mice that had a germline deletion of MKL1 (MKL1 (-,-)) to determine the role that MKL1 plays in the development of bleomycin-induced pulmonary fibrosis.

METHODS

Bleomycin or normal saline were intratracheally delivered to 9 to 12 week old female MKL1 (+,+) and MKL1 (-,-) mice. Mice were assessed for weight loss and survival to 28 days. Inflammatory responses were assessed through bronchoalveolar lavage at days 3 and 7 post-treatment. The development of pulmonary fibrosis was characterized using hydroxyproline assay and histological staining. MKL1 (+,+) and MKL1 (-,-) mouse lung fibroblasts were isolated to compare morphologic, gene expression and functional differences.

RESULTS

MKL1 (-,-) mice demonstrated increased survival, attenuated weight loss, and decreased collagen accumulation compared to wild-type animals 28-days after intratracheal instillation of bleomycin. Histological analysis demonstrated decreased trichrome, smooth muscle α-actin, and fibronectin staining in MKL1(-,-) mice compared to MKL1 (+,+) controls. Differential cell counts from bronchoalveolar lavage demonstrated that there was attenuated neutrophilia 3 days after bleomycin administration, but no difference at day 7. Isolated mouse lung fibroblasts from MKL1 (-,-) mice had decreased contractility and deposited less fibronectin matrix compared to wild-type controls, suggesting a defect in key remodeling functions.

CONCLUSIONS

Altogether, these data demonstrate that MKL1 plays a significant role in mediating the fibrotic response to bleomycin injury. Loss of MKL1 attenuated early neutrophil influx, as well as myofibroblast-mediated remodeling. Targeting MKL1 activity may therefore be a useful strategy in treating pulmonary fibrosis.

Inhibition of myocardin-related transcription factor/serum response factor signaling decreases lung fibrosis and promotes mesenchymal cell apoptosis

Myofibroblasts are crucial to the pathogenesis of tissue fibrosis. Their formation of stress fibers results in the release of myocardin-related transcription factor (MRTF), a transcriptional coactivator of serum response factor (SRF). MRTF-A (Mkl1)-deficient mice are protected from lung fibrosis. We hypothesized that the SRF/MRTF pathway inhibitor CCG-203971 would modulate myofibroblast function in vitro and limit lung fibrosis in vivo. Normal and idiopathic pulmonary fibrosis lung fibroblasts were treated with/without CCG-203971 (N-[4-chlorophenyl]-1-[3-(2-furanyl)benzoyl]-3-piperidine carboxamide) and/or Fas-activating antibody in the presence/absence of transforming growth factor (TGF)-β1, and apoptosis was assessed. In vivo studies examined the effect of therapeutically administered CCG-203971 on lung fibrosis in two distinct murine models of fibrosis induced by bleomycin or targeted type II alveolar epithelial injury. In vitro, CCG-203971 prevented nuclear localization of MRTF-A; increased the apoptotic susceptibility of normal and idiopathic pulmonary fibrosis fibroblasts; blocked TGF-β1-induced myofibroblast differentiation; and inhibited TGF-β1-induced expression of fibronectin, X-linked inhibitor of apoptosis, and plasminogen activator inhibitor-1. TGF-β1 did not protect fibroblasts or myofibroblasts from apoptosis in the presence of CCG-203971. In vivo, CCG-203971 significantly reduced lung collagen content in both murine models while decreasing alveolar plasminogen activator inhibitor-1 and promoting myofibroblast apoptosis. These data support a central role of the SRF/MRTF pathway in the pathobiology of lung fibrosis and suggest that its inhibition can help resolve lung fibrosis by promoting fibroblast apoptosis.