Regression of collagen-induced arthritis with taxol, a microtubule stabilizer

Low dose Taxol ameliorated renal fibrosis in mice with diabetic kidney disease by downregulation of HIPK2

Our previous studies reported that low-dose paclitaxel (Taxol) ameliorated renal fibrosis in the unilateral ureteral obstruction and remnant kidney models. However, the regulatory role of Taxol in diabetic kidney disease (DKD) is still unclear. Herein, we observed that low-dose Taxol attenuated high glucose-increased expression of fibronectin, collagen I and collagen IV in Boston University mouse proximal tubule cells. Mechanistically, Taxol suppressed the expression of homeodomain-interacting protein kinase 2 (HIPK2) via disrupting the binding of Smad3 to HIPK2 promoter region, and consequently inhibited the activation of p53. Besides, Taxol ameliorated RF in Streptozotocin mice and db/db-induced DKD via suppression of Smad3/HIPK2 axis as well as inactivation of p53. Altogether, these results suggest that Taxol can block Smad3-HIPK2/p53 axis, thereby attenuating the progression of DKD. Hence, Taxol is a promising therapeutic drug for DKD.

Protective effects of paclitaxel on thioacetamide-induced liver fibrosis in a rat model

Liver fibrosis is a public health burden that is highly associated with morbidity and mortality. Therefore, this study aims to explore the anti-fibrotic effects of low dose of paclitaxel (PTX) against thioacetamide (TAA)-induced liver fibrosis in rats and the possible mechanisms involved. TAA was administered at a dose of 200 mg/kg twice weekly for 6 weeks in rats to induce liver fibrosis similar to that in humans. Liver dysfunction was shown by increased alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and γ-glutamyl transferase, along with histopathological changes. Liver fibrosis was confirmed by Masson's Trichome staining, increased collagen content, and elevated α-smooth muscle actin (α-SMA) protein expression. In addition, TAA induced liver apoptosis as indicated by the increased terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells in liver tissues. This study demonstrated that the administration of PTX (0.3 mg/kg/i.p.) three times a week for 6 weeks significantly alleviated functional and biochemical changes induced by TAA in addition to improving the liver architecture. PTX attenuated liver fibrosis as reflected by the decreased collagen content and α-SMA protein expression. Additionally, PTX attenuated liver apoptosis as indicated by the decreased TUNEL-positive cells. Moreover, PTX prevented TAA-induced elevation of transforming growth factor-β1 (TGF-β1), platelet-derived growth factor-BB (PDGF-BB), and tissue inhibitor of metalloproteinase 1 (TIMP-1) levels in liver tissues. These findings suggest that the low dose of PTX prevented TAA-induced liver fibrosis in rats, possibly by inhibiting the expression of TGF-β1 and PDGF-BB and subsequently suppressing the apoptosis and the expression of TIMP-1.

Paclitaxel alleviates liver fibrosis induced by bile duct ligation in rats: Role of TGF-β1, IL-10 and c-Myc

Liver fibrosis is a global health issue that causes morbidity and mortality with no currently available treatment. It has been shown that low dose paclitaxel (PTX) can stabilize microtubules and inhibit the profibrotic transforming growth factor-beta 1 (TGF-β1) signaling pathway. In this study the effect of treatment with low dose PTX was examined using a model of cholestatic liver fibrosis. Bile-duct ligation (BDL) was induced in rats for 2 weeks then PTX (0.3 mg/kg/ip) was administered three times a week for 2 weeks. Administration of PTX ameliorated BDL-induced elevation in biomarkers of hepatocellular damage (alanine transaminase; ALT and aspartate transaminase; AST) and obstructive cholestatic injury (total bilirubin and gamma glutamyl transferase; γ-GT). PTX was able to correct the increase in liver weight to body weight ratio and the bile duct proliferation induced by BDL. Additionally, PTX treatment corrected the BDL-induced fibrosis of portal tracts, elevation of hydroxyproline content and increased alpha smooth muscle actin (α-SMA) mRNA and protein expression. This antifibrotic effect of PTX was further examined through its inhibitory effect on TGF-β1 mRNA and protein expression in addition to c-Myc mRNA expression. Furthermore, PTX rectified the BDL-induced decrease in interleukin-10 (IL-10) mRNA and protein expression. In conclusion, this study suggests that PTX at low dose has the potential to treat BDL-induced liver fibrosis in rats possibly through suppression of TGF-β1 and c-Myc and activation of IL-10 pathways.

Thermogel Loaded with Low-Dose Paclitaxel as a Facile Coating to Alleviate Periprosthetic Fibrous Capsule Formation

Medical-grade silicones as implants have been utilized for decades. However, the postoperative complications, such as capsular formation and contracture, have not yet been fully controlled and resolved. The aim of the present study is to elucidate whether the capsular formation can be alleviated by local and sustained delivery of low-dose paclitaxel (PTX) during the critical phase after the insertion of silicone implants. A biocompatible and thermogelling poly(lactic acid- co-glycolic acid)- b-poly(ethylene glycol)- b-poly(lactic acid- co-glycolic acid) triblock copolymer was synthesized by us. The micelles formed by the amphiphilic polymers in water could act as a reservoir for the solubilization of PTX, a very hydrophobic drug. The concentrated polymer aqueous solution containing PTX exhibited a sol-gel transition upon heating and formed a thermogel depot at body temperature. In vitro release tests demonstrated that the entrapped microgram-level PTX displayed a sustained release manner up to 57 days without a significant initial burst effect. Customized silicone implants coated with the PTX-loaded thermogels at various drug concentrations were inserted into the pockets of the subpanniculus carnosus plane of rats. The histological observations performed 1 month postoperation showed that the sustained release of PTX with an appropriate dose significantly reduced the peri-implant capsule thickness, production and deposition of collagen, and expression of contracture-mediating factors compared with bare silicone implants. More importantly, such an optimum dose had an excellent repeatability for the suppression of the capsular formation. Therefore, this study provides a strategic foothold regarding the sustained release of low-dose PTX to alleviate fibrotic capsule formation after implantation, and the microgram-level PTX-loaded thermogel holds great potential as an "all-purpose antifibrosis coating" for veiling the surfaces of various implantable medical devices.

Paclitaxel-Coated Balloons: Investigation of Drug Transfer in Healthy and Atherosclerotic Arteries - First Experimental Results in Rabbits at Low Inflation Pressure

Purpose

Beyond antiproliferative properties, paclitaxel exhibits anti-inflammatory activity, which might be beneficial in the local treatment of nonocclusive coronary artery disease. Paclitaxel release and tissue concentrations after paclitaxel-coated balloon treatment using different pressures have not been investigated so far. The aim of the study was to investigate in an atherosclerotic rabbit model whether drug transfer from paclitaxel-coated balloons into the vessel wall is affected by the presence of atherosclerotic lesions and to which extent it depends on the inflation pressure used.

Methods

Paclitaxel-coated balloons (3.5 μg/mm² paclitaxel) were inflated with pressures of 1, 2, or 6 atm (60s) in healthy (n = 39) and atherosclerotic (n = 22) arteries of New Zealand White Rabbits. Paclitaxel content in arterial walls (10 min after interventions) and paclitaxel remaining on balloons after treatment were analyzed using high-performance liquid chromatography.

Results

Median paclitaxel tissue concentrations were 829.3 μg/g (IQR 636.5–1487 μg/g) in healthy and 375.7 μg/g (IQR 169.8–771.6 μg/g) in atherosclerotic arteries (p = 0.0002). The paclitaxel tissue concentration was dependent on inflation pressure (1 atm vs. 2 atm vs. 6 atm) in atherosclerotic arteries (p = 0.0106) but not in healthy arteries (p ≥ 0.05).

Conclusions

Atherosclerotic lesions impede the transfer of paclitaxel into arterial walls. Higher inflation pressures resulted in an increased paclitaxel transfer in atherosclerotic but not in healthy arteries. However, it is assumed that the tissue concentrations achieved with an inflation pressure of 2 atm are potentially effective in this model.

Taxol alleviates collagen-induced arthritis in mice by inhibiting the formation of microvessels

The objective of the present study is to evaluate the inhibitory effects of taxol (PTX) on angiogenesis in a collagen-induced arthritis (CIA) mouse model. Collagen II (C II) and complete Freund’s adjuvant (CFA) were used in C57BL/6 (H-2b) mice to generate the CIA model. Random grouping was performed in the normal control group, CIA model group, PTX 1.5 mg/kg group, PTX 1.0 mg/kg group, and PTX 0.5 mg/kg group. Arthritis index scores, tissue pathology scores, and synovium microvessel density (MVD) analysis were performed. Immunohistochemistry and enzyme-linked immunosorbent assay were used to detect the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-α (HIF-1α). The correlation between MVD and pathological scores and between MVD and the expression of VEGF as well as HIF-1α in the synovium were also evaluated. After PTX treatment, the three intervention group arthritis index scores were reduced when compared with the CIA group. The total histological scores in the three PTX treatment groups were lower than those in the CIA group. Similarly, PTX significantly alleviated the scores for synovitis, pannus formation, and bone destruction. Compared with the CIA group, the MVD of the three intervention groups decreased in a dose-dependent manner. The expression of VEGF and HIF-1α in synovial tissues and serum also significantly decreased after PTX treatment. Further analysis showed that MVD and pathological scores and MVD and expression of VEGF as well as HIF-1α in the synovium were positively correlated. PTX may alleviate CIA by suppressing angiogenesis, providing new insights into the treatment of rheumatoid arthritis (RA). VEGF and HIF-1α may be targets for PTX suppression of microvessel formation.

Citrullination in Rheumatoid Arthritis-A Process Promoted by Neutrophil Lysis?

Anti-citrullinated protein antibodies (ACPAs) are highly specific serologic markers for rheumatoid arthritis (RA) and can pre-date clinical disease onset by up to 10 years, also predicting erosive disease. The process of citrullination, the post-translational conversion of arginine to citrulline residues, is mediated by peptidylarginine deiminase (PAD) enzymes present in polymorphonuclear cells (PMNs). Calcium ions (Ca²⁺) are required for PAD activation, but the intracellular Ca²⁺ concentration in normal cells is much lower than the optimal Ca²⁺ concentration needed for PAD activation. For this reason, it has been proposed that PAD activation, and thus citrullination, occurs only during PMN cell death when PAD enzymes leak out of the cells into the extracellular matrix, or extracellular Ca²⁺ enters the cells, with the high Ca²⁺ concentration activating PAD. Recently, using artificial in vitro systems to corroborate their hypothesis, Romero et al. demonstrated that "hypercitrullination," citrullination of multiple intracellular proteins, occurs within synovial fluid (SF) cells of RA patients, and that only modes of death leading to membranolysis such as perforin-granzyme pathway or complement membrane attack complex activation cause hypercitrullination. In order for Romero's hypothesis to hold, it is reasonable to surmise that PMN-directed lysis should occur in the rheumatoid joint or the circulation of RA patients. Research conducted thus far has shown that immunoglobulin G (IgG) targeting PMNs are present in RA SF and mediate PMN activation. However, the role of anti-PMN IgG in mediating complement activation and subsequent PMN lysis and hypercitrullination has not been fully evaluated.

Paclitaxel: new uses for an old drug

Paclitaxel (Taxol), one of the most important anticancer drugs, has been used for therapy of different types of cancers. Mechanistically, paclitaxel arrests cell cycle and induces cell death by stabilizing microtubules and interfering with microtubule disassembly in cell division. Recently, it has been found that low-dose paclitaxel seems promising in treating non-cancer diseases, such as skin disorders, renal and hepatic fibrosis, inflammation, axon regeneration, limb salvage, and coronary artery restenosis. Future studies need to understand the mechanisms underlying these effects in order to design therapies with specificity.

Microtubule-stabilizing agents delay the onset of EAE through inhibition of migration

We have shown previously that microtubule-stabilizing agents (MSA), a class of anti-proliferative compounds, can delay disease onset and reduce cumulative disease in an experimental model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). To explore how MSA could alter EAE disease processes, we compared the effect of administering MSA before or after peak antigen-specific proliferation and found that treatment before proliferation completely inhibited antigen-specific responses in the spleen; whereas administration of an MSA such as paclitaxel or docetaxel after peak proliferation did not. Despite the presence of antigen-specific responses in mice treated at the later time point, both treatment periods resulted in similar protection against EAE, suggesting that the protective effect of MSA in EAE could not be solely attributed to anti-proliferative activity. Instead, using in vivo migration assays, it was shown that MSA inhibit immune cell infiltration into the central nervous system (CNS). Furthermore, we found that the efficacy of an MSA could be enhanced by administering low doses of two different MSA together, such as peloruside A and ixabepilone, indicating that these MSA synergize in vivo to suppress disease. Taken together, these data suggest that MSA can suppress EAE by at least two distinct mechanisms of action--prevention of proliferation and inhibition of migration into the CNS. Finally, we have shown that a combination treatment with synergizing MSA may provide enhanced protection at lower therapeutic doses.

Molecular pathways and functional analysis of miRNA expression associated with paclitaxel-induced apoptosis in hepatocellular carcinoma cells

BACKGROUND

We postulated that microRNAs (miRNAs) might be involved in hepatocellular carcinoma (HCC) targeted chemotherapy with paclitaxel. This study sought to generate a list of potential miRNA-based biomarkers and their potential targets to better understand the response to paclitaxel treatment in HCC.

METHODS

Cell viability proliferation assays were conducted to test the sensitivity of the HepG2 cells to paclitaxel. The morphological changes of apoptosis were assessed with 4',6-diamidino-2-phenylindole staining. Differential expression patterns of miRNA in the HepG2 cells either treated or not treated were analyzed using miRNA microarrays.

RESULTS

The array experiments have identified 54 miRNAs whose basal expression levels differed by >2-fold and p < 0.05 between the two phenotypic groups. The data were validated by a quantitative real-time PCR of 8 selected miRNAs (miR-21, miR-1274a, miR-1260, miR-1290, miR-508-5p, miR-877, miR-1246, miR-183*). The PI3K/Akt, mitogen-activated protein kinase (MAPK), TGF-β, ErbB, p53, cell cycle, mammalian target of rapamycin, and Jak-STAT signaling pathways were involved in paclitaxel-induced apoptosis.

CONCLUSIONS

The manipulation of one or more of these miRNAs could be an important approach for the improved management of paclitaxel therapy.

Low-dose paclitaxel ameliorates pulmonary fibrosis by suppressing TGF-β1/Smad3 pathway via miR-140 upregulation

Abnormal TGF-β1/Smad3 activation plays an important role in the pathogenesis of pulmonary fibrosis, which can be prevented by paclitaxel (PTX). This study aimed to investigate an antifibrotic effect of the low-dose PTX (10 to 50 nM in vitro, and 0.6 mg/kg in vivo). PTX treatment resulted in phenotype reversion of epithelial-mesenchymal transition (EMT) in alveolar epithelial cells (AECs) with increase of miR-140. PTX resulted in an amelioration of bleomycin (BLM)-induced pulmonary fibrosis in rats with reduction of the wet lung weight to body weight ratios and the collagen deposition. Our results further demonstrated that PTX inhibited the effect of TGF-β1 on regulating the expression of Smad3 and phosphorylated Smad3 (p-Smad3), and restored the levels of E-cadherin, vimentin and α-SMA. Moreover, lower miR-140 levels were found in idiopathic pulmonary fibrosis (IPF) patients, TGF-β1-treated AECs and BLM-instilled rat lungs. Through decreasing Smad3/p-Smad3 expression and upregulating miR-140, PTX treatment could significantly reverse the EMT of AECs and prevent pulmonary fibrosis of rats. The action of PTX to ameliorate TGF-β1-induced EMT was promoted by miR-140, which increased E-cadherin levels and reduced the expression of vimentin, Smad3 and p-Smad3. Collectively, our results demonstrate that low-dose PTX prevents pulmonary fibrosis by suppressing the TGF-β1/Smad3 pathway via upregulating miR-140.

Control of myofibroblast differentiation by microtubule dynamics through a regulated localization of mDia2

Myofibroblast differentiation plays a critical role in wound healing and in the pathogenesis of fibrosis. We have previously shown that myofibroblast differentiation is mediated by the activity of serum response factor (SRF), which is tightly controlled by the actin polymerization state. In this study, we investigated the role of the microtubule cytoskeleton in modulating myofibroblast phenotype. Treatment of human lung fibroblasts with the microtubule-destabilizing agent, colchicine, resulted in a formation of numerous stress fibers and expression of myofibroblast differentiation marker proteins. These effects of colchicine were independent of Smad signaling but were mediated by Rho signaling and SRF, as they were attenuated by the Rho kinase inhibitor, Y27632, or by the SRF inhibitor, CCG-1423. TGF-β-induced myofibroblast differentiation was not accompanied by gross changes in the microtubule polymerization state. However, microtubule stabilization by paclitaxel attenuated TGF-β-induced myofibroblast differentiation. Paclitaxel had no effect on TGF-β-induced Smad activation and Smad-dependent gene transcription but inhibited actin polymerization, nuclear accumulation of megakaryoblastic leukemia-1 protein, and SRF activation. The microtubule-associated formin, mDIA2, localized to actin stress fibers upon treatment with TGF-β, and paclitaxel prevented this localization. Treatment with the formin inhibitor, SMI formin homology 2 domain, inhibited stress fiber formation and myofibroblast differentiation induced by TGF-β, without affecting Smad-phosphorylation or microtubule polymerization. Together, these data suggest that (a) TGF-β promotes association of mDia2 with actin stress fibers, which further drives stress fiber formation and myofibroblast differentiation, and (b) microtubule polymerization state controls myofibroblast differentiation through the regulation of mDia2 localization.

Inhibiting citrullination in rheumatoid arthritis: taking fuel from the fire

Citrullination is a post-translational modification catalysed by peptidylarginine deiminase and is a common feature of inflammation. The presence of anti-citrullinated protein/peptide antibodies (ACPA), however, is unique to rheumatoid arthritis. Several lines of evidence suggest that ACPA are important in the pathogenesis of rheumatoid arthritis. A popular hypothesis for this pathogenesis is a two-hit model. The first hit gives rise to ACPA, and the second hit, an unrelated episode of synovial inflammation accompanied by citrullination, is perpetuated by the pre-existing antibodies. This model suggests that reducing citrullination might ameliorate disease. Recent findings indicate that citrullination closely correlates with inflammation, and that glucocorticoids decrease peptidylarginine deiminase expression independent of their other anti-inflammatory effects.

Inhibition of CYP450 1A and 3A by berberine in crucian carp Carassius auratus gibelio

Berberine has long been considered as an antibiotic candidate in aquaculture. However, studies regarding its effects on drug-metabolizing enzymes in fish are still limited. In the present study, the effects of berberine on cytochrome P4501A (CYP1A) and CYP3A in crucian carp were investigated. Injection of different concentrations of berberine (0, 5, 25, 50, and 100mg/kg) inhibited the CYP1A mRNA expression, thereby inhibiting further the catalytic activity of CYP1A-related ethoxyresorufin-O-deethylase (EROD). Furthermore, both CYP1A expression and EROD activity were further inhibited with increasing berberine concentrations. In addition, the CYP3A expressions at both the mRNA and the protein levels were downregulated by higher berberine concentrations. The catalytic activity of CYP3A-related erythromycin N-demethylase (ERND) was also inhibited by berberine at a dose of no less than 25mg/kg. Moreover, at the berberine concentration exceeding 25mg/kg, the inhibition of CYP3A expression and ERND activity increased with increasing berberine concentrations. In vitro experiments were also performed. When berberine was pre-incubated with the crucian carp liver microsomes, it competitively inhibited the corresponding EROD activity with the IC(50) of 11.7 μM. However, the ERND activity was slightly inhibited by berberine with the IC(50) of 206.4 μM. These results suggest that, in crucian carp, berberine may be a potent inhibitor to CYP1A, whereas the CYP3A inhibition needs a higher concentration of berberine.

Low-dose paclitaxel ameliorates fibrosis in the remnant kidney model by down-regulating miR-192

Transforming growth factor (TGF)-β has been shown to play a central role in the development of tubulointerstitial fibrosis, which can be corrected via treatment with paclitaxel. The biology of microRNA (miR) can be modulated by paclitaxel. We hypothesized that paclitaxel may attenuate renal fibrosis in a rat model of remnant kidney disease by inhibiting TGF-β induced-miRs. Rats in groups of 12 were subjected to 5/6 nephrectomy and received low-dose intraperitoneal injection of paclitaxel. Renal functions were assessed at 8 weeks. The TGF-β signalling cascade and ECM proteins were evaluated by real-time polymerase chain reaction (TRT–PCR) and immunofluorescence microscopy. Animals with remnant kidneys developed hypertension, which was not relieved with paclitaxel treatment. However, paclitaxel treatment resulted in dampening the proteinuric response, reduction in serum BUN, creatinine levels and urine protein : creatinine ratio and normalization of creatinine clearance. These effects were accompanied by the inhibition of Smad2/3 activation, attenuation of renal fibrosis and normalization of integrin-linked kinase (ILK), COL(I)A1, COL(IV)A2 and α-SMA expression. Also, paclitaxel down-regulated the expression of miR-192, miR-217 and miR -377, while miR-15 was up-regulated in the remnant kidney. In vitro, in tubular epithelial cells (NRK-52E), paclitaxel also inhibited TGF-β1-induced Smad2/3 activation and normalized ILK, COL(I)A1, COL(IV)A2 and α-SMA expression. Furthermore, ChIP analyses indicated that Taxol suppressed Smad3-mediated miR-192 transcriptional activity. Over-expression of miR-192 in NRK-52E mimicked the changes seen in the remnant kidney, while inclusion of miR-192 inhibitor in the culture medium blocked TGF-β1-induced COL(I)A1 and COL(IV)A2 expression, while ILK and α-SMA were unaffected. These data suggest that low-dose paclitaxel ameliorates renal fibrosis via modulating miR-192 pathobiology and TGF-β/Smad signalling. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Immunomodulation of Autoimmune Arthritis by Herbal CAM

Rheumatoid arthritis (RA) is a debilitating autoimmune disease of global prevalence. The disease is characterized by synovial inflammation leading to cartilage and bone damage. Most of the conventional drugs used for the treatment of RA have severe adverse reactions and are quite expensive. Over the years, increasing proportion of patients with RA and other immune disorders are resorting to complementary and alternative medicine (CAM) for their health needs. Natural plant products comprise one of the most popular CAM for inflammatory and immune disorders. These herbal CAM belong to diverse traditional systems of medicine, including traditional Chinese medicine, Kampo, and Ayurvedic medicine. In this paper, we have outlined the major immunological pathways involved in the induction and regulation of autoimmune arthritis and described various herbal CAM that can effectively modulate these immune pathways. Most of the information about the mechanisms of action of herbal products in the experimental models of RA is relevant to arthritis patients as well. The study of immunological pathways coupled with the emerging application of genomics and proteomics in CAM research is likely to provide novel insights into the mechanisms of action of different CAM modalities.

Paclitaxel ameliorates fibrosis in hepatic stellate cells via inhibition of TGF-beta/Smad activity

AIM

To investigated if paclitaxel can attenuate hepatic fibrosis in rat hepatic stellate cells (RHSCs).

METHODS

RHSCs were cultured in vitro and randomly assigned to four groups: normal control group (treated only with Dulbecco's Modified Eagle's Medium), Taxol group (200 nmol/L paclitaxel was added to the cell culture), transforming growth factor (TGF)-beta group (5 ng/mL recombinant human TGF-beta1 was added to the cell culture), and TGF-beta + Taxol group. TGF-beta signaling cascade and status of various extracellular matrix proteins were evaluated by real time reverse transcriptase polymerase chain reaction and Western blotting.

RESULTS

The paclitaxel treatment markedly suppressed Smad2/3 phosphorylation. This was associated with attenuated expression of collagen I and III and fibronectin in RHSCs.

CONCLUSION

These data indicate that 200 nmol/L paclitaxel ameliorates hepatic fibrosis via modulating TGF-beta signaling, and that paclitaxel may have some therapeutic value in humans with hepatic fibrosis.

Paclitaxel ameliorates fibrosis in hepatic stellate cells via inhibition of TGF-β/Smad activity

AIM: To investigated if paclitaxel can attenuate hepatic fibrosis in rat hepatic stellate cells (RHSCs).

METHODS: RHSCs were cultured in vitro and randomly assigned to four groups: normal control group (treated only with Dulbecco’s Modified Eagle’s Medium), Taxol group (200 nmol/L paclitaxel was added to the cell culture), transforming growth factor (TGF)-β group (5 ng/mL recombinant human TGF-β1 was added to the cell culture), and TGF-β + Taxol group. TGF-β signaling cascade and status of various extracellular matrix proteins were evaluated by real time reverse transcriptase polymerase chain reaction and Western blotting.

RESULTS: The paclitaxel treatment markedly suppressed Smad2/3 phosphorylation. This was associated with attenuated expression of collagen I and III and fibronectin in RHSCs.

CONCLUSION: These data indicate that 200 nmol/L paclitaxel ameliorates hepatic fibrosis via modulating TGF-β signaling, and that paclitaxel may have some therapeutic value in humans with hepatic fibrosis.

Bacterial and human peptidylarginine deiminases: targets for inhibiting the autoimmune response in rheumatoid arthritis?

Peptidylarginine deiminases (PADs) convert arginine within a peptide (peptidylarginine) into peptidylcitrulline. Citrullination by human PADs is important in normal physiology and inflammation. Porphyromonas gingivalis, a major pathogen in periodontitis, is the only prokaryote described to possess PAD. P. gingivalis infection may generate citrullinated peptides, which trigger anti-citrullinated peptide antibodies. In susceptible individuals, host protein citrullination by human PADs in the joint probably perpetuates antibody formation, paving the way for the development of chronic arthritis. Blockades of bacterial and human PADs may act as powerful novel therapies by inhibiting the generation of the antigens that trigger and sustain autoimmunity in rheumatoid arthritis.

Low-dose paclitaxel ameliorates renal fibrosis in rat UUO model by inhibition of TGF-beta/Smad activity

Transforming growth factor-beta (TGF-beta) has a pivotal function in the progression of renal fibrosis in a wide variety of renal diseases. Smad proteins have been identified to have an important function in regulating the expression of extracellular matrix (ECM) proteins through TGF-beta signaling pathway. Aberrant TGF-beta/Smad signaling can be modulated by stabilization of microtubules with paclitaxel. In this study, we investigated if paclitaxel can attenuate tubulointerstitial fibrosis in a rat model of unilateral ureteral obstruction (UUO). Rats in groups of six were subjected to UUO and received low-dose intraperitoneal injection of paclitaxel (0.3 mg/kg) twice a week. They were killed at day 7 and 14 after UUO or Sham operation. TGF-beta signaling cascade and status of various ECM proteins were evaluated by RT-PCR, western blotting and immunohistochemical or immunofluorescence staining. The paclitaxel treatment markedly suppressed Smad2 and Smad3 phosphorylation. This was associated with attenuated expression of integrin-linked kinase, collagens I and III, fibronectin (FN) and alpha-smooth muscle actin, and a substantial decrease in renal fibrosis in animals that underwent UUO and received paclitaxel. These data indicate that the low-dose paclitaxel ameliorates renal tubulointerstitial fibrosis by modulating TGF-beta signaling, and thus, the paclitaxel may have some therapeutic value in humans.

Delaying the onset of experimental autoimmune encephalomyelitis with the microtubule-stabilizing compounds, paclitaxel and Peloruside A

The hallmark of autoimmunity is the activation and proliferation of autoreactive lymphocytes. Therefore, one potential strategy to treat autoimmunity is to target the proliferating autoreactive lymphocytes with antimitotic drugs. Paclitaxel and peloruside are two microtubule-stabilizing drugs that halt cell proliferation by stabilizing microtubules in the G(2)/M phase of the cell cycle. C57BL/6 mice treated for 5 consecutive days with paclitaxel or peloruside had a reduced incidence and significantly delayed development of EAE, a mouse model of MS. Although paclitaxel and peloruside were effective at inhibiting T cell proliferation in vitro, paclitaxel was shown to be ineffective at preventing the proliferation of autoreactive T cells in vivo during the 5-day treatment period. However, after the 5-day treatment, the ability of splenocytes or LN cells to proliferate in vitro was reduced significantly, suggesting that drug treatment targeted late but not early proliferative events in the animal. Moreover, in paclitaxel-treated, MOG-immunized mice, there was a complete inhibition of the recruitment of myeloid cells (especially macrophages) to the peripheral lymphoid organs. These results indicate that microtubule-stabilizing drugs are effective at reducing disease but require a prolonged exposure to paclitaxel in vivo to alter proliferation in the myeloid and lymphoid cell compartments.

Disease modifying and antiangiogenic activity of 2-methoxyestradiol in a murine model of rheumatoid arthritis

Background

A critical component of disease progression in rheumatoid arthritis (RA) involves neovascularization associated with pannus formation. 2-methoxyestradiol (2ME2) is a naturally occurring molecule with no known physiologic function, although at pharmacologic concentrations it has antiproliferative and antiangiogenic activities. We investigated the impact of orally administered 2ME2 on the initiation and development of proliferative synovitis using the anti-collagen monoclonal antibodies (CAIA) model.

Methods

Severe polyarticular arthritis was induced in Balb/c female mice by administration of 2 mg of a monoclonal antibody cocktail intravenously into the tail vein of mice. Twenty-four hours following monoclonal antibody administration, mice were injected with 25 μg of LPS (E. coli strain 0111:B4) via the intraperitoneal route. Treatment with 2ME2 (100, 75, 50, 25, 10, 1 mg/kg, p.o., daily), or vehicle control began 24 hrs following LPS challenge and continued to day 21. Hind limbs were harvested, sectioned and evaluated for DMARD activity and general histopathology by histomorphometric analysis and immunohistochemistry (vWF staining). In a separate study, different dosing regimens of 2ME2 (100 mg/kg; q.d. vs q.w. vs q.w. × 2) were evaluated. The effect of treatment with 2ME2 on gene expression of inflammatory cytokines and angiogenic growth factors in the joint space was evaluated 5 and 14 days after the induction of arthritis.

Results

Mice treated with 2ME2 beginning 24 hours post anti-collagen monoclonal antibody injection, showed a dose-dependent inhibition in mean arthritic scores. At study termination (day 21), blinded histomorphometric assessments of sectioned hind limbs demonstrated decreases in synovial inflammation, articular cartilage degradation, pannus formation, osteoclast activity and bone resorption. At the maximal efficacious dosing regimen (100 mg/kg/day), administration of 2ME2 resulted in total inhibition of the study parameters and prevented neovascularization into the joint. Examination of gene expression on dissected hind limbs from mice treated for 5 or 14 days with 2ME2 showed inhibition of inflammatory cytokine message for IL-1β, TNF-α, IL-6 and IL-17, as well as the angiogenic cytokines, VEGF and FGF-2.

Conclusion

These data demonstrate that in the CAIA mouse model of RA, 2ME2 has disease modifying activity that is at least partially attributable to the inhibition of neovascular development. Further, the data suggests new mechanistic points of intervention for 2ME2 in RA, specifically inhibition of inflammatory mediators and osteoclast activity.

Involution of collagen-induced arthritis with an angiogenesis inhibitor, PPI-2458

Pannus formation, in both rheumatoid arthritis (RA) and collagen-induced arthritis (CIA), is angiogenesis-dependent. PPI-2458 [(1R)-1-carbamoyl-2-methyl]-carbamic acid-(3R,3S,5S, 6R)-5-methoxy-4-[(2R,3R)-2-methyl-3-(3-methyl-but-2-enyl)oxiranyl]-1-oxaspiro(2*5)oct-6-yl ester], a new fumagillin derivative known to inhibit methionine aminopeptidase 2 (MetAP-2) and endothelial proliferation at the late G(1) phase, was evaluated in CIA rats to study its potential to involute synovitis. Arthritic syngeneic LOU rats received either a vehicle control or various dosages of oral, intravenous, or subcutaneous PPI-2458. Plasma samples were analyzed to determine a pharmacokinetic profile of PPI-2458, and whole blood was evaluated by flow cytometry to assess the effect on lymphocyte subsets. At 15 mg/kg i.v., 30 mg/kg s.c., or 100 mg/kg p.o., there was a significant reduction in clinical severity scores (p < 0.001) and blinded radiographic scores (p < 0.001) compared with vehicle control groups. Structural damage was virtually eliminated with PPI-2458. Continuous inhibition of MetAP-2 was needed to maintain benefits, although pannus involution could be achieved with the inhibitor when escape flares occurred. Pharmacokinetic analysis after a single p.o. dose showed a rapid T(max) value of 15 min followed by biphasic elimination (t(1/2), approximately 20 min and t(1/2), approximately 5 h) and an estimated oral bioavailability of approximately 15%. Flow cytometry revealed a dose-dependent decrease in white blood cells and lymphocytes manifested as decreases in circulating CD3+ T cells and natural killer cells. PPI-2458, however, did not seem to be immunosuppressive, as determined by delayed-type hypersensitivity or IgG antibody assays. These studies indicate that the MetAP-2 inhibitor PPI-2458 can regress established CIA and that angiogenic mechanisms might be important targets in the treatment of other pannus-mediated diseases such as RA.

Angiogenesis inhibition as a therapeutic approach for inflammatory synovitis

Angiogenesis inhibition, long studied in the treatment of malignancies, has begun to emerge as a potential therapeutic approach in managing inflammatory arthritis, particularly rheumatoid arthritis. The growth of new vessels is required for the development of the rheumatoid pannus, which then leads to extensive synovial inflammation and joint destruction. Vascular endothelial growth factor is the best studied mediator of angiogenesis, and several therapies have been developed that specifically target this molecule. Several other angiogenesis mediators, such as the angiopoietin-TIE system, hypoxia inducible factor and integrin alpha(V)beta(3), as well as naturally occurring inhibitors of angiogenesis, are also being investigated as potential therapeutic targets. Additionally, there are a number of drugs, including paclitaxel, 2-methoxyestradiol and fumagillin analogs, that might have a role in inhibiting angiogenesis and, thus, in treating proliferative synovitis.

Drugs to suppress cough

Cough is an important defensive reflex of the airway and also a common symptom of respiratory disease. Cough after common respiratory virus infection is transient but is more persistent when associated with conditions such as asthma, rhinosinusitis, gastro-oesophageal reflux, chronic obstructive pulmonary disease and lung cancer. Persistent cough may be due to peripheral and/or central sensitisation of cough reflexes initiated by cough receptors, rapidly adapting receptors or nociceptors. Treatment directed at associated conditions such as asthma (with anti-inflammatories) and gastro-oesophageal reflux (with proton-pump inhibitors) improve cough. There remains a need to use drugs that suppress the neural activity of cough (termed nonspecific), as treatments directed at the clinical cause(s) of the underlying cough (termed specific) may not be effective. The most effective indirect antitussives are opioids such as morphine, codeine or pholcodeine, but they produce side effects such as drowsiness, nausea, constipation and physical dependence. Opioids such as kappa- and delta-receptor agonists, non-opioids such as nociceptin, neurokinin and bradykinin receptor antagonists, cannabinoids, vanilloid receptor-1 antagonists, blockers of Na+-dependent channels, and large conductance Ca2+-dependent K+-channel activators of afferent nerves may represent novel antitussives.

Paclitaxel modulates TGFbeta signaling in scleroderma skin grafts in immunodeficient mice

BACKGROUND

Systemic sclerosis (SSc) is characterized by excessive fibrosis and obliterative vascular lesions. Abnormal TGFbeta activation is implicated in the pathogenesis of SSc. Aberrant TGFbeta/Smad signaling can be controlled by stabilization of microtubules with paclitaxel.

METHODS AND FINDINGS

SSc and healthy human skin biopsies were incubated in the presence or absence of paclitaxel followed by transplantation into severe combined immunodeficient mice. TGFbeta signaling, fibrosis, and neovessel formation were evaluated by quantitative RT-PCR and immunohistochemical staining. Paclitaxel markedly suppressed Smad2 and Smad3 phosphorylation and collagen deposition in SSc grafts. As a result, the autonomous maintenance/reconstitution of the SSc phenotype was prevented. Remarkably, SSc grafts showed a 2-fold increase in neovessel formation relative to normal grafts, regardless of paclitaxel treatment. Angiogenesis in SSc grafts was associated with a substantial increase in mouse PECAM-1 expression, indicating the mouse origin of the neovascular cells.

CONCLUSION

Low-dose paclitaxel can significantly suppress TGFbeta/Smad activity and lessen fibrosis in SCID mice. Transplantation of SSc skin into SCID mice elicits a strong angiogenesis-an effect not affected by paclitaxel. Although prolonged chemotherapy with paclitaxel at higher doses is associated with pro-fibrotic and anti-angiogenic changes, the findings described here indicate that low-dose paclitaxel may have therapeutic benefits for SSc via modulating TGFbeta signaling.

New antiangiogenic strategies for the treatment of proliferative synovitis

Angiogenesis inhibition, which has been extensively studied for the treatment of various malignancies, is beginning to emerge as a new potential therapy for proliferative synovitis, particularly rheumatoid arthritis (RA). The rheumatoid pannus, the site of inflammation and joint destruction in the rheumatoid synovium, relies on the development of new vasculature to sustain its growth. A host of mediators have been shown to induce angiogenesis at the site of the inflamed synovium; these include vascular endothelial growth factor, fibroblast growth factor, integrin alpha(V)beta3, angiopoietin, prosta-glandin E1 and prostaglandin E2, and matrix metalloproteinases. In addition, hypoxia at the site of synovial inflammation contributes to angiogenesis stimulation. Several naturally-occurring inhibitors exist, such angiostatin and endostatin. There are a number of drugs undergoing study in the treatment of proliferative synovitis, which capitalise on the correlation between angiogenesis inhibition and the reduction of signs and symptoms of RA. Paclitaxel and an anti-integrin alpha(V)beta3 antibody, LM-609, are currently in clinical trials. Other drugs that may inhibit angiogenesis in RA include TNP-470 (formerly called AGM-1470), PPI-2458, PTK-787, bevacizumab and thalidomide. Many of these drugs have shown promise for the treatment of oncologic disorders, and are now being evaluated for the treatment of proliferative synovitis.

Micellar paclitaxel improves severe psoriasis in a prospective phase II pilot study

BACKGROUND

Taxanes (eg, paclitaxel) are chemotherapeutic agents that have antiproliferative, antiangiogenic, and antiinflammatory properties.

OBJECTIVE

We sought to explore the safety and efficacy of paclitaxel in individuals with severe psoriasis.

METHODS

An open-label, prospective, phase II pilot study was conducted at the National Institutes of Health Clinical Center, a federal government medical research facility, in Bethesda, Maryland. Twelve patients with severe psoriasis, as defined by a baseline Psoriasis Area and Severity Index (PASI) score of >or= 20), were studied. Initially, patients received 6 intravenous infusions of micellar paclitaxel, 75 mg/m(2), at 4-week intervals (stage I). Later patients received 9 intravenous infusions of micellar paclitaxel at 2-week intervals (37.5 mg/m(2) for 3 doses followed by 50 mg/m(2) for six additional doses) (stage II). The primary end point was the percent change in the PASI from week 0 to week 24 in stage I and from week 0 to week 20 in stage II.

RESULTS

In stage I, all 5 patients improved (mean = 59.7% decrease in PASI, median = 59.6%, range: 40.3%-79.2%). Four of the 7 patients completed stage II and all of these patients improved (mean = 45.9% decrease in PASI, median = 45.0%, range: 14.6%-79.1%). Micellar paclitaxel was well tolerated by most patients.

CONCLUSIONS

Micellar paclitaxel demonstrates therapeutic activity in patients with severe psoriasis.

5-Aza-2′-deoxycytidine and paclitaxel inhibit inducible nitric oxide synthase activation in fibrosarcoma cells

Given the important role of gaseous free radical nitric oxide (NO) in tumor cell biology, we investigated the ability of the anti-cancer drugs 5-Aza-2'-deoxycytidine (ADC) and paclitaxel to modulate NO production in mouse L929 fibrosarcoma cells. Both drugs reduced IFN-gamma-stimulated NO release in cultures of L929 and primary fibroblasts, but not in mouse peritoneal macrophages. The inhibitory effect was due to the reduced expression of inducible NO synthase (iNOS), the enzyme responsible for cytokine-induced intracellular NO synthesis, as both agents markedly suppressed the interferon-gamma (IFN-gamma)-triggered increase in iNOS concentration in L929 cells. In addition, ADC and paclitaxel prevented the IFN-gamma-triggered activation of p44/p42 mitogen-activated protein (MAP) kinase in L929 fibroblasts, suggesting a possible mechanism for the observed inhibition of iNOS expression. These results might have important implications for the therapeutic effect of ADC and paclitaxel, since their inhibitory action on NO release partly neutralized the NO-dependent toxicity of IFN-gamma on L929 fibrosarcoma cells.

The immunopharmacology of paclitaxel (Taxol®), docetaxel (Taxotere®), and related agents

Paclitaxel (Taxol) and docetaxel (Taxotere) are among the most unique, and successful, chemotherapeutic agents used for the treatment of breast and ovarian cancer. Both agents have anti-mitotic properties derived from binding to tubulin and excessive stabilization of microtubules. Their anti-neoplastic effects derive from this mechanism. Distinct from their effects on microtubule stabilization, paclitaxel, docetaxel, and related taxanes display immunopharmacological traits. In this review, we discuss their induction of pro-inflammatory genes and proteins; the current hypotheses on the molecular mechanism for this induction, especially its relationship to the lipopolysaccharide (LPS) signaling pathway. We also discuss the structure-activity relationships (SAR) that govern gene induction, especially the striking differences between the SAR for murine and human cells in vitro. Lastly, we discuss the immunopharmacological traits of paclitaxel and docetaxel in terms of their relevance to human clinical pharmacology and toxicology and their activity in animal models of autoimmune disorders.

Polyether-polyester diblock copolymers for the preparation of paclitaxel loaded polymeric micelle formulations

A number of hypersensitivity reactions have been attributed to the presence of Cremophor((R)) EL in the current formulation for paclitaxel. This has led to the development of formulations for paclitaxel employing polyether-polyester diblock copolymers as micelle forming carriers. Diblock copolymers of methoxypolyethylene glycol-block-poly(D,L-lactide) (MePEG:PDLLA) were synthesized from monomers of D,L-lactide and MePEG by a ring opening bulk polymerization in the presence of stannous octoate. Up to 25% paclitaxel could be loaded into matrices of MePEG:PDLLA (60:40, MePEG molecular weight of 2000) using the solution casting method. Dissolution of paclitaxel/copolymer matrices in aqueous media resulted in complete solubilization of paclitaxel within the hydrophobic PDLLA core of the micelles. This review article describes the synthetic reaction conditions influencing the degree of conversion of monomer to copolymer, thermal properties, critical micelle concentrations of copolymers, methods of incorporation of paclitaxel into copolymer matrices and subsequent constitution in aqueous media and biological evaluations of micellar paclitaxel.

Effects of paclitaxel on cultured synovial cells from patients with rheumatoid arthritis

BACKGROUND

Proliferation of synovial cells is considered to play a key role in rheumatoid arthritis (RA). Using paclitaxel, a unique antineoplastic agent known to suppress collagen-induced arthritis, we conducted an in vitro study of cell kinetics on cultured synovial cells from patients with RA.

METHODS

Alterations of the cell cycle of cultured fibroblast-like synovial cells (FLSs) from patients with RA were studied using flow cytometry and laser scanning cytometry. Apoptosis and accumulation of cyclin concerning effects of paclitaxel were detected.

RESULTS

Paclitaxel induced arrest of the cell cycle at G2/M phase and apoptosis in FLSs. The late stage of apoptosis was determined by the positivity of terminal deoxynucleotidyl transferase assay. Morphological observation by combined usage of both annexin V and propidium iodide on FLSs on a slide glass showed early apoptotic changes in detail. FLSs arrested at G2/M phase showed marked accumulation of cyclin B1. The effects of paclitaxel decreased on FLSs, which diminished proliferative activity.

CONCLUSIONS

These data indicate that paclitaxel induces cell arrest at G2/M phase followed by apoptosis in human FLSs, which have high proliferative activity, and possible therapeutic effects of paclitaxel on RA.

Inhibition of experimental allergic encephalomyelitis in the Lewis rat by paclitaxel

Experimental allergic encephalomyelitis (EAE), an animal model for multiple sclerosis (MS), is useful for preclinical testing for agents to be considered for treatment for this human demyelinating disease. Microtubules in lymphocytes play an important role in the cascade of human T cell activation, and paclitaxel (PTX), a microtubule stabilizer, can inhibit T cell function. A new formulation of micellar PTX, free of Cremophor and ethanol, was tested for its effect on the induction of EAE in Lewis rats. Adoptive EAE was induced with an encephalitogenic T cell line activated with guinea pig myelin basic protein (GP MBP) peptide 68-88. PTX (10 mg/kg) was administered 24 and 72 h after cell transfer. The clinical signs, fulminating in controls, were completely blocked by PTX, but mild CNS inflammation remained unaltered. A similar dose of PTX, given on days 6 and 8 to animals developing active EAE after immunization with GP MBP peptide 68-88 in complete Freund's adjuvant, greatly reduced the severity of paralysis and delayed the onset of disease by 8-9 days. Marked weight loss and severe toxicity were noted with higher and more prolonged administration. In vitro micellar PTX inhibited activation of encephalitogenic T cells by both specific antigen and mitogen. Lower doses and longer treatment programs may provide effective treatment with acceptable adverse effects with this agent in the treatment of inflammatory demyelinating disease.

Effect of Taxol and Taxotere on Gene Expression in Macrophages: Induction of the Prostaglandin H Synthase-2 Isoenzyme

Induction of genes encoding cytokines or other, unidentified proteins may contribute to the pharmacological effects of taxol. We hypothesized that prostaglandin H synthase-2 (PGHS-2) was one of the unidentified genes induced by taxol. Taxol alone or taxol plus IFN-γ increased PGE2 formation, PGHS-2 protein expression, and PGHS-2 mRNA expression in RAW 264.7 murine macrophages. The kinetics for mRNA induction, protein expression, and catalysis were self-consistent. A selective inhibitor of PGHS-2 blocked PGE2 formation by cells incubated with taxol; a selective inhibitor of PGHS-1 had no effect. A glucocorticoid blocked the induction of mRNA, the expression of PGHS-2 protein, and the formation of PGE2. Neither taxol alone nor taxol plus IFN-γ altered the expression of the PGHS-1 isoenzyme in RAW 264.7 cells. Taxotere, an analogue that stabilizes microtubules as potently as taxol, did not alter the expression of PGHS-2, implying that its induction in RAW 264.7 murine macrophages did not originate from microtubule stabilization. Taxol and taxotere each induced PGHS-2 expression in human monocytes suspended in 10% human serum. However, human monocytes suspended in 10% bovine serum responded only to LPS, not to taxol or taxotere, implying that they act independently of the LPS-mimetic process that is prominent in mice. Taxol induced PGHS-2 in human and murine monocytes via a p38 mitogen-associated protein kinase pathway. The inclusion of PGHS-2 among the early response genes induced in leukocytes may be relevant to the beneficial and adverse effects encountered during taxol administration.

Paclitaxel reduces anti-dsDNA antibody titer and BUN, prolonging survival in murine lupus

We evaluated the effect of paclitaxel on the severity of autoimmunity in the murine model of systemic lupus erythematosus (SLE), NZB x NZW F1 mice. Fifteen 20 week old (NZB x NZW) F1 female mice were given a dose of 10 mg/kg paclitaxel by the intraperitoneal route on three alternate days followed by 7.5 mg/kg on three additional alternate days. This pattern of treatment was repeated every 4 weeks for a period of 28 weeks. 20 control mice were injected intraperitoneally with an equal volume of the vehicle used. Serum anti-double stranded DNA (dsDNA) antibody titers and the blood urea nitrogen (BUN) were significantly diminished in the paclitaxel treated group compared to the vehicle treated group. While the onset of proteinuria appeared to be delayed in the experimental group, the difference was not significant. Survival rate improved significantly in paclitaxel treated group (p = 0.04 by log-rank test). These results suggest that paclitaxel is beneficial in the suppression of autoimmunity in this strain of mice by reducing the anti-dsDNA antibody titer and the BUN, prolonging survival.

Inhibition of activator protein 1 activity by paclitaxel suppresses interleukin-1-induced collagenase and stromelysin expression by bovine chondrocytes

OBJECTIVE

Cytokine-induced collagenase 1 (matrix metalloproteinase 1 [MMP-1]) and stromelysin 1 (MMP-3) expression is dependent on activator protein 1 (AP-1) activation and have a fundamental role in the pathophysiology of arthritic diseases by degrading connective tissues. This study evaluates the effect of paclitaxel on AP-1 activation and examines its effect on the expression of 2 major matrix metalloproteinases, MMP-1 and MMP-3, and its effect on AP-1 activation.

METHODS

MMP-1, MMP-3, c-fos, and c-jun messenger RNA (mRNA) levels were measured in interleukin-1 (IL-1)-induced primary chondrocytes in the presence and absence of paclitaxel. The effect of paclitaxel on AP-1 promoter activity was studied by chloramphenicol acetyltransferase assays in IL-1-stimulated chondrocytes. The same conditions were applied to studies of the effect of paclitaxel on binding at the AP-1 site by gel-shift mobility assays. The cytotoxicity effect of paclitaxel on chondrocytes was studied by examining cell viability and expression of the matrix molecules aggrecan and type II collagen.

RESULTS

IL-1-induced MMP-1 and MMP-3 mRNA levels were markedly reduced in paclitaxel-treated chondrocytes. Further, IL-1-induced AP-1 activation and AP-1 binding were inhibited by paclitaxel. However, there was no effect on the expression of c-fos or c-jun mRNA levels. Chondrocyte viability was not affected by paclitaxel, and there was no effect on the expression of housekeeping genes or the major cartilage matrix molecules aggrecan and type II collagen.

CONCLUSION

These studies demonstrate that paclitaxel is a potent inhibitor of MMP-1 and MMP-3 synthesis through the AP-1 site. However, inhibition of AP-1 activity by paclitaxel does not affect the viability of chondrocytes or the expression of matrix molecules.

Taxol involution of collagen-induced arthritis: ultrastructural correlation with the inhibition of synovitis and neovascularization

Collagen-induced arthritis (CIA) is an animal model of rheumatoid arthritis (RA) that can be regressed with Taxol (paclitaxel), a chemotherapeutic agent. To identify structural changes that occur with involution, the synovium from naive, untreated CIA, and Taxol-treated CIA rats were evaluated by light microscopy plus transmission and scanning electron microscopy. Analysis included detailed images of vascular networks using polymeric corrosion casts. The CIA synovium was morphologically similar to human RA synovium. In CIA, the integrity of the intimal lining is lost by Type-B synoviocytes becoming highly elongated and polarized toward the joint space, resulting in non-overlapping cellular processes and the elimination of the basal lamina. In addition, the lining expanded from a width of 6-10 microns in naives to 200-250 microns in CIA due primarily to increased numbers of both Type-A and -B synoviocytes and more interstitial matrix. Vascular corrosion casts of CIA synovium illustrated a marked increase in blood vessel volume and an extensive interconnecting vascular architecture; neovascular arrays were observed to project toward the synovial surface. In Taxol-treated CIA, the synoviocyte and neovascular components reverted to the naive synovium morphology, suggesting that this agent might be useful in the therapy of RA.

The role of plant-derived drugs and herbal medicines in healthcare

Many of our present medicines are derived directly or indirectly from higher plants. While several classic plant drugs have lost much ground to synthetic competitors, others have gained a new investigational or therapeutical status in recent years. In addition, a number of novel plant-derived substances have entered into Western drug markets. Clinical plant-based research has made particularly rewarding progress in the important fields of anticancer (e.g. taxoids and camptothecins) and antimalarial (e.g. artemisinin compounds) therapies. In addition to purified plant-derived drugs, there is an enormous market for crude herbal medicines. Natural product research can often be guided by ethnopharmacological knowledge, and it can make substantial contributions to drug innovation by providing novel chemical structures and/or mechanisms of action. In the end, however, both plant-derived drugs and crude herbal medicines have to take the same pharmacoeconomic hurdle that has become important for new synthetic pharmaceuticals.

Collagen-induced arthritis, an animal model of autoimmunity

Collagen induced arthritis (CIA) is an autoimmune model that in many ways resembles rheumatoid arthritis (RA). Immunization of genetically susceptible strains of rodents and primates with type II collagen (CII) leads to the development of a severe polyarticular arthritis that is mediated by an autoimmune response. Like RA, synovitis and erosions of cartilage and bone are hallmarks of CIA, and susceptibility to both RA and CIA is linked to the expression of specific MHC class II molecules. Although not identical to RA, CIA clearly establishes the biological plausibility that an autoimmune reaction to a cartilage component can lead to a chronic, destructive, polyarthritis. Although it is induced in susceptible animals by immunization with heterologous CII, it is the autoreactive component of the immune response that leads to disease. A wealth of evidence indicates that synovitis is initiated by the production of pathogenic autoreactive antibodies capable of fixing and activating complement. The elucidation of the specific amino acid sequences of collagen that are recognized by the MHC molecules has enabled at least two approaches to specific immunotherapy to be considered. Firstly, small synthetic peptides representing dominant epitopes have been used as effectively as the original antigen as a tolerogen. The rather fastidious physicochemical properties of collagen that make it difficult for its routine use in therapy are thereby circumvented by the use of oligopeptides. Secondly, analysis of the specific amino acid side chains that are involved in MHC contact and TCR recognition enables analog peptides to be devised which can specifically and exquisitely inhibit the response to CII, preventing the onset of arthritis. Further investigations involving this model may contribute to the development of specific immunotherapies in the human disorder.

Paclitaxel selectively induces mitotic arrest and apoptosis in proliferating bovine synoviocytes

OBJECTIVE

Rheumatoid arthritis (RA) is characterized by chronic progressive destruction of joints involving several disease processes, such as villous hypertrophy, proliferation of synovial lining cells, and infiltration of inflammatory cells. Synovial cell activation and proliferation is thought to be a key step in the destruction of cartilaginous and bony tissues in RA joints. In view of the invasive properties of synoviocytes in RA, we conducted in vitro studies to determine the mechanism of action of paclitaxel (Taxol) on synoviocytes, which may account for the inhibition of joint destruction found when this agent is administered.

METHODS

Cultured synovial cells were treated with various concentrations of paclitaxel and were evaluated by cell viability, fluorescence microscopy, flow cytometry of DAPI-stained cells, and electron microscopy.

RESULTS

The data indicated that paclitaxel inhibited synoviocyte proliferation by a G2/M phase block and was toxic to synoviocytes by inducing apoptosis. Confluent cells such as chondroyctes and synoviocytes were not affected by paclitaxel. Synchronization of synovioyctes at the G1/S boundary effectively abolished paclitaxel-induced apoptosis.

CONCLUSION

The data indicate that induction of apoptosis in synoviocytes might be dependent on transit through the cell cycle, specifically through G2 and mitosis. Further, paclitaxel was selectively toxic to proliferating synoviocytes but spared nonproliferating synoviocytes and chondrocytes. These results demonstrate that paclitaxel can inhibit synovial cell proliferation and pannus formation in RA joints in vivo. We suggest that paclitaxel be considered as a prototypical compound for a new class of potential chondroprotective agents.

Calcium pyrophosphate dihydrate crystals activate MAP kinase in human neutrophils: inhibition of MAP kinase, oxidase activation and degranulation responses of neutrophils by taxol

The activation of MAP kinase in human neutrophils stimulated by both uncoated and plasma-opsonized crystals of triclinic calcium pyrophosphate dihydrate (CPPD) was investigated. The effect of taxol on MAP kinase activation and on the responses of neutrophils stimulated by plasma-opsonized crystals was determined. MAP kinase activation was identified and quantified in Mono Q chromatography separated fractions of neutrophils that had been incubated with CPPD crystals by measuring [gamma-32P]adenosine triphosphate (ATP) phosphorylation of myelin basic protein and using immunoblotting techniques. Human neutrophils were incubated with taxol (0-50 microM), added to plasma-opsonized CPPD (50 mg/ml) and MAP kinase activation, chemiluminescence, superoxide anion generation, lysozyme and myeloperoxidase release were monitored. Both uncoated and plasma coated CPPD crystals induced a large increase in MAP kinase activity in neutrophils over control levels within 1 min of incubation. Pretreatment of neutrophils with taxol was able to suppress this activation of MAP kinase. Taxol produced a concentration-dependent inhibition of opsonized CPPD-induced neutrophil chemiluminescence, superoxide anion production and myeloperoxide release. Taxol at 28 microM also significantly inhibited chemiluminescence, superoxide anion production and myeloperoxidase release from neutrophils stimulated by opsonized zymosan. This is the first report of crystal-induced activation of MAP kinase in neutrophils. Microtubule-associated processes, such as signal transduction, secretion and phagocytosis are involved in particulate-induced neutrophil responses. We have suggested that the inhibitory effect of taxol observed in this work is due to its stabilizing effect on microtubules and disruption of MAP kinase activation associated with microtubules.