Effect of rifampicin on the risk of steroid-induced osteonecrosis of the femoral head.

OBJECTIVE: To investigate the effects and possible mechanism of rifampicin on steroid-induced osteonecrosis of the femoral head (ONFH). METHODS: Bone marrow stromal cells (BMSC) separated from male rats were cultured in vitro without any treatment (Group mA), exposed to dexamethasone (Group mB), treated with rifampicin (Group mC), and exposed to dexamethasone and rifampicin simultaneously (Group mD) respectively (n = 5 in each group). After 7 days, P-glycoprotein (P-gp) activity and adipogenesis of the BMSC were evaluated. In an in vivo experiment, 80 rats were randomly divided into 4 groups (n= 20 in each group). Group A received intragastric saline for 5 weeks. Group B received intragastric saline for one week, followed by subcutaneous methylprednisolone and saline for 4 weeks. Group C received intragastric rifampicin for 5 weeks. Group D received intragastric rifampicin for one week, followed by subcutaneous methylprednisolone and rifampicin for 4 weeks. At the end of the experiment, all rats underwent analysis of P-gp activity of BMSC, P-gp expression in the femoral heads, MRI and histomorphometry of the femoral heads. RESULTS: In vitro, the P-gp activity of BMSC increased and lipid accumulation decreased significantly in Group mD, compared to Group mB. In vivo, P-gp activity and P-gp expression in Group D increased compared to Group B. The mean area of MRI abnormal signal, adipocytic variables and apoptotic cells in Group D decreased, mean percentage of the whole epiphysis made up by the epiphyseal ossification center and trabecular structure variables improved compared to those in Group B. The incidence of ONFH was lower in Group D (50%) than in Group B (80%). CONCLUSION: Rifampicin may decrease the risk of steroid-induced ONFH by enhancing P-gp activity, thus preventing steroid-induced BMSC adipogenesis.

Inhibition of glycogen synthase kinase-3beta attenuates glucocorticoid-induced bone loss.

AIMS: Long-term glucocorticoid administration is known to induce bone deterioration. Glycogen synthase kinase-3beta (GSK-3beta) signaling reportedly participates in bone remodeling. This study investigated whether GSK-3beta inhibitor could regulate glucocorticoid-induced inhibition of osteoblast differentiation in vitro or bone mass in vivo. MAIN METHODS: MC3T3-E1 osteoblasts were treated with kinase-inactive GSK-3beta mutant and 6-bromoindirubin-3'-oxim (BIO) and then exposed to 1microM dexamethasone. Survival and osteoblast differentiation of cell cultures were assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling, quantitative RT-PCR, and von Kossa staining. Mineral density, biomechanical properties and microenvironments of BIO- and glucocorticoid-treated rat bone tissues were analyzed using dual-energy X-ray absorptiometry, material testing, and histomorphometry, respectively. KEY FINDINGS: Glucocorticoid decreased levels of phosphorylated Ser9-GSK-3beta and beta-catenin in osteoblast cultures. Kinase-inactive GSK-3beta mutant and BIO treatments attenuated dexamethasone-induced inhibition of beta-catenin, Runx2 abundance, and osteoblast differentiation but suppressed glucocorticoid-induced apoptosis of cell cultures. Exogenous BIO treatment alleviated methylprednisolone-induced impairment of mineral density, biomechanical strength, trabecular bone volume, osteoblast surface, and bone formation rate of rat bone tissue. BIO treatment also attenuated glucocorticoid-induced promotion of osteoclast surface and marrow adipocyte volume in bone tissue. Bone cells adjacent to glucocorticoid-stressed bone tissue displayed strong phosphorylated Ser9-GSK-3beta and beta-catenin immunostaining following BIO treatment. SIGNIFICANCE: Inhibition of GSK-3beta abrogated glucocorticoid-induced bone loss by increasing beta-catenin- and Runx2-mediated osteoblast differentiation. Controlling GSK-3beta signaling in bone cells may be a strategy for preventing glucocorticoid-induced osteopenia.

Effects of sodium hyaluronate and methylprednisolone acetate on proteoglycan synthesis in equine articular cartilage explants.

OBJECTIVE: To determine effects of sodium hyaluronate (HA) on corticosteroid-induced cartilage matrix catabolism in equine articular cartilage explants. SAMPLE POPULATION: 30 articular cartilage explants from fetlock joints of 5 adult horses without joint disease. PROCEDURE: Articular cartilage explants were treated with control medium or medium containing methylprednisolone acetate (MPA; 0.05, 0.5, or 5.0 mg/mL), HA (0.1, 1.0, or 1.5 mg/mL), or both. Proteoglycan (PG) synthesis was measured by incorporation of sulfur 35-labeled sodium sulphate into PGs, and PG degradation was measured by release of radiolabeled PGs into the medium. Total glycosaminoglycan (GAG) content in media and explants and total explant DNA were determined. RESULTS: Methylprednisolone acetate caused a decrease in PG synthesis, whereas HA had no effect. Only the combination of MPA at a concentration of 0.05 mg/mL and HA at a concentration of 1.0 mg/mL increased PG synthesis, compared with control explants. Methylprednisolone acetate increased degradation of newly synthesized PGs into the medium, compared with control explants, and HA alone had no effect. Hyaluronate had no effect on MPA-induced PG degradation and release into media. Neither MPA alone nor HA alone had an effect on total cartilage GAG content. Methylprednisolone acetate caused an increase in release of GAG into the medium at 48 and 72 hours after treatment. In combination, HA had no protective effect on MPA-induced GAG release into the medium. Total cartilage DNA content was not affected by treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicate that HA addition has little effect on corticosteroid-induced cartilage matrix PG catabolism in articular cartilage explants.

Effects of anabolic steroids on diaphragm impairment induced by methylprednisolone in emphysematous hamsters.

This study was designed to investigate whether the administration of the anabolic steroid nandrolone decanoate is able to antagonize the loss in diaphragm function induced by long-term administration of a low-dose of methylprednisolone in emphysematous hamsters. Normal and emphysematous male hamsters were randomized to receive either saline or methylprednisolone 0.2 mg x kg(-1) x day(-1) for 9 months, with or without nandrolone decanoate 1 mg x kg(-1) x week(-1) i.m. during the final 3 months. Diaphragm contractile properties and myosin heavy chain composition were determined. Compared to control hamsters, the force generating capacity of isolated diaphragm strips decreased by approximately 12% in the emphysema group and by approximately 22% in the emphysema plus methylprednisolone group. Addition of nandrolone decanoate to the emphysema plus methylprednisolone hamsters significantly improved force generation. The atrophy of type IIa and IIx diaphragm fibres in the emphysema plus methylprednisolone group was completely reversed to the level of control hamsters by the addition of nandrolone decanoate. In conclusion, nandrolone decanoate in part reversed the loss in diaphragm force-generating capacity in emphysematous hamsters treated with methylprednisolone, and reversed type IIa and IIx fibre atrophy completely.

Two potentially angiostatic factors, a steroid and L-azetidine-2-carboxylic acid, antagonize one another.

The proline analogue L-azetidine-2-carboxylic acid (LACA) systemically suppressed mast-cell-mediated angiogenesis, as measured by the rat mesenteric-window method. Dexamethasone and methylprednisolone at very low and non-toxic s.c. doses also somewhat inhibited the angiogenesis. Most interestingly, the co-administration of either of these steroids with LACA paradoxically stimulated angiogenesis. These findings suggest that in the future search for candidates for clinically-useful systemic angiostatic remedies, one may have to focus not only on the effect of individual drugs or agents, but also on the effect of such putative anti-angiogenic agents when co-administered. The fact that two potentially angiostatic agents can antagonize one another has not previously been reported.

Effect of intramuscularly administered polysulfated glycosaminoglycan on articular cartilage from equine joints injected with methylprednisolone acetate.

Intra-articularly administered, long-acting corticosteroids are a beneficial treatment for many equine joint disorders because they alleviate inflammation and signs of pain, but they also exert detrimental effects on the biochemical composition and morphologic features of articular cartilage. Chondroprotective drugs have been shown to mitigate some of the deleterious effects of intra-articularly administered corticosteroids on articular cartilage of laboratory animals. Twenty-one ponies were assigned at random to receive 1 of 3 treatments in the right middle carpal joint. Group-1 ponies (n = 8) had methylprednisolone acetate (MPA; 0.2 mg/kg of body weight) and saline solution administered intra-articularly and IM, respectively. Group-2 ponies (n = 9) received MPA (0.2 mg/kg) and polysulfated glycosaminoglycan (GAG; 2 mg/kg). Group-3 ponies (control; n = 4) had saline solution administered intra-articularly and IM. The corticosteroid or saline solution was injected into the right middle carpal joint on day 1. The IM administered polysulfated GAG or saline solution was administered at the same time, then was repeated every 3 days for 20 days. Ponies were euthanatized 21 days after initial injection by overdose of pentobarbital sodium. The cartilage of younger ponies was significantly (P < 0.05) more responsive to the proteoglycan-depleting effects of MPA. Ponies < 10 years old of groups 1 and 2 had significantly (P < 0.05) lower GAG content in the articular cartilage than did control ponies. Systemic treatment with polysulfated GAG did not result in a protective effect against proteoglycan loss from the articular cartilage.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth hormone prevents steroid-induced growth depression in health and uremia.

Treatment with supraphysiological doses of corticosteroids results in protein wasting and impairment of growth, whereas exogenous growth hormone (GH) causes anabolism and improvement of growth. We wanted to know whether the growth depressing effects of methylprednisolone (MP) are more expressed in an organism which is chronically diseased and whether these effects can be counterbalanced by concomitant treatment with recombinant human growth hormone (rhGH). MP in doses from 1 to 9 mg/kg/day caused a dose dependent reduction of length gain, weight gain and weight gain/food intake ratio in 140 g healthy female Sprague-Dawley rats. Food intake was not affected by MP. This points to a change in food metabolism as a mechanism for growth impairment. In addition, treatment with MP inhibited endogenous GH secretion, documented by serum GH concentration profiles over seven hours, decreased IGF-1 serum concentration and disturbed growth cartilage plate architecture. Concomitant treatment with 2.5 to 20 IU/rhGH/kg/day prevented the negative effects of MP on growth in a dose dependent manner and normalized growth plate architecture. In uremic rats in which food efficiency and growth was already reduced, 6 mg MP/kg/day further decreased length gain and prevented weight gain completely by bringing the weight gain/food conversion ratio to the nadir. All effects of MP including reduction of muscle mass could be prevented by concomitant treatment with 10 IU rhGH/kg/day. The effects of MP and rhGH on food efficiency and growth in uremic animals were numerically nearly identical to those in pair fed ad libitum fed controls, but this may be more relevant in the diseased organism in which basal growth is already suppressed.

Recombinant human growth hormone overcomes the growth-suppressive effect of methylprednisolone in uraemic rats.

Paediatric renal allograft recipients frequently manifest growth retardation because of suboptimal graft function and/or concomitant corticosteroid treatment. To determine if the growth-suppressive effects of methylprednisolone (MP) could be counterbalanced by concomitant treatment with recombinant human growth hormone (rhGH) under conditions of normal and reduced renal function, the following animal model was set up. Female uraemic Sprague-Dawley rats (140 g) together with pair-fed and ad libitum-fed control animals were treated with 6 mg/kg per day MP with or without 10 IU/kg per day rhGH. MP suppressed linear growth and weight gain by 43% and 63%, respectively in ad libitum-fed normal control animals; the suppression was more pronounced in uraemic animals (57% and 107%, respectively). The suppressive effects were independent of food intake. The food conversion ratio (weight gain/food intake) was diminished to one-third in control and to more than one-tenth in uraemic animals. Concomitant treatment with rhGH completely reversed the suppression of length gain and weight gain (total body and muscle) and normalized the food conversion ratio. We concluded that rhGH can completely reverse the catabolic effects of corticosteroids under conditions of normal or reduced renal function. The data provide a reasonable rationale for prospective controlled studies on the use of rhGH treatment in paediatric kidney transplant recipients with growth failure.

TGF-beta 1 accelerates wound healing: reversal of steroid-impaired healing in rats and rabbits.

TGF-beta modulates events of normal wound healing through multiple pathways that influence cell infiltration, proliferation, angiogenesis, extracellular matrix synthesis and remodeling. The effects of topically applied TGF-beta 1 on wound healing in two models of healing were evaluated when the healing response was impaired by the administration of methylprednisolone to rats or rabbits. TGF-beta 1 increased the healing of linear incision wounds on rats, as measured by breaking strength, to that of normal rats. Full thickness open wounds were also created on the inner ears of rabbits to simulate a non-contracting wound with limited blood supply. Healing was further impaired by the administration of methylprednisolone. The single application of TGF-beta 1 improved the healing of open wounds. TGF-beta 1 stimulated increased granulation tissue formation, as well as reepithelialization. The amount of granulation tissue and epithelialization were similar to wounds from normal-healing control rabbits. The delayed healing caused by methylprednisolone permitted the evaluation of multiple applications of TGF-beta 1 to wounds. Two applications of TGF-beta 1 spaced 7 days apart further improved the healing response when compared to a single application. Thus, single or multiple topical applications of TGF-beta 1 reversed impaired healing conditions secondary to methylprednisolone when used on incisional or open wounds. These observations support the hypothesis that growth factors, such as TGF-beta 1, may be useful as accelerators of wound repair in patients with impaired healing conditions.

Vitamin A and corticosteroid interaction in wound healing in rats.

The possible antagonistic interaction of vitamin A and corticosteroids in wound healing was studied in several groups of rats. Follow-up showed that hydrocortisone did not delay wound healing, whereas a long-acting preparation of 6 alpha-methylprednisolone (DEPO-MEDROL) suppressed spontaneous healing of open wounds. Topical application of vitamin A caused a further delay in healing, whereas systemic use of vitamin A had no consistent effect. Since no beneficial effect of vitamin A could be demonstrated, and in view of its possible toxicity, we recommend that the clinical use of vitamin A in wound treatment be reconsidered.