Aging Clin Exp Res DOI 10.1007/s40520-013-0192-9

ORIGINAL ARTICLE

Interplay of vitamin D and nitric oxide in post-menopausal knee osteoarthritis Mohamed A. Abu el Maaty • Rasha S. Hanafi Samir El-Badawy • Mohamed Z. Gad



Received: 6 November 2013 / Accepted: 11 December 2013 Ó Springer International Publishing Switzerland 2013

Abstract Aim Mounting evidence has presented nitric oxide (NO) and vitamin D (vitD) as having independently complex roles in osteoarthritis (OA). However, a mechanistic or an observational connection between them has never been investigated in the disease. This study investigates the correlation between circulating 25-hydroxyvitamin D [25(OH)D] and total NO as nitrate/nitrite (NOx) in patients with knee OA. Methods The recruited subjects comprised 36 post-menopausal women with knee OA, ages 50–60 years, as well as 10 healthy males, 20–30 years of age. 25(OH)D and NOx levels were determined using high-performance liquid chromatography and spectrophotometrically using Griess reaction, respectively. Results The mean (SEM) 25(OH)D and NOx concentrations of OA patients were 25.0 (1.6) ng/mL and 32.45 (2.18) lM, respectively, and 35.4 (2.1) ng/mL and 25.49 (2.23) lM, respectively, for controls. Comparison of mean 25(OH)D and NOx concentrations of OA patients and controls yielded significant results (P = 0.001 and 0.034, respectively). NO notably decreased with decreasing 25(OH)D concentration in patients. However, significant M. A. Abu el Maaty  M. Z. Gad (&) Biochemistry Department, Faculty of Pharmacy and Biotechnology, German University in Cairo, Al Tagamoa Al Khames, New Cairo 11835, Egypt e-mail: [email protected] R. S. Hanafi Pharmaceutical Chemistry Department, Faculty of Pharmacy and Biotechnology, German University in Cairo, New Cairo, Egypt S. El-Badawy Rheumatology Department, Faculty of Medicine, Cairo University, Giza, Egypt

results in terms of mean NOx concentration were observed in the comparison of normal and deficient vitD OA groups (P = 0.048). Conclusion Results suggest that vitD increases NO production and inducible NO synthase expression in osteoarthritic chondrocytes possibly leading to a protective effect. Keywords

Knee osteoarthritis  Nitric oxide  Vitamin D

Introduction Osteoarthritis (OA), the once upon a time dull disease, is no longer viewed in this light. Besides being the most common form of arthritis [1], international concern over this disease rises from the expected increase in its prevalence in the coming years, since obesity and aging are both risk factors associated with it [1]. Interestingly, there is no accurate census on the worldwide prevalence of the disease. The complexity of OA stems from the fact that its etiology remains unknown [2] and that there is no known cure [3]. All pharmacological interventions aim at treating the pain that comes along. Two putative players add to the complexity of OA, vitamin D and nitric oxide (NO). The former, now known to have non-skeletal actions mediated via the vitamin D receptor [4], has quite a controversial role in the disease. While some observational studies have demonstrated the association of circulating levels of the vitamin with the incidence [5–8] and progression [9] of different forms of OA, others have denied an existing relationship [10]. A randomized-controlled trial is currently being undertaken to elucidate vitamin D’s protective effect against OA [11]. Meanwhile, a recent article showed that vitamin D supplementation for 2 years at a dose sufficient to elevate

123

Aging Clin Exp Res

25-hydroxyvitamin D plasma levels to higher than 36 ng/ mL did not reduce knee pain or cartilage volume loss in patients with symptomatic knee OA [12]. Research to unveil NO’s role in OA has been sparked by the 1992 discovery of increased concentration of nitrite (an NO metabolite) in serum and synovial fluid samples of patients with rheumatic diseases including OA [13]. This suggested an increase in NO synthesis in such conditions and, thus, a role for the molecule in the pathogenesis of the disease. On that note, contradicting molecular studies ever since have presented NO as having a protective and detrimental role in OA [14]. Identification of vitamin D response elements in the nitric oxide synthase (NOS) gene has bridged the gap between vitamin D and NO [15]. It has been reported that 1,25-dihydroxyvitamin D [1,25(OH)2D], the hormonally active form of the vitamin [4], modulates NO production and/or inducible NOS (iNOS) expression in an array of cells including endothelial cells [16], osteoblasts [15], microglial cells [17], macrophages [17] and astrocytes [17]. To our knowledge, such activity has not been investigated by previous molecular studies on chondrocytes and observational studies linking circulating 25-hydroxyvitamin D [25(OH)D] with NO in OA are also lacking. The purpose of this study was therefore to investigate the concentration of circulating plasma NO, as total nitrate/ nitrite (NOx), in post-menopausal women with knee osteoarthritis, compare it with previously reported reference values and correlate it with 25(OH)D levels.

Materials and methods Subjects 36 post-menopausal female patients, all between 50 and 60 years of age (54.7 ± 3.2 years), with clinically diagnosed knee OA were recruited, over the month of January, from the Rheumatology Outpatient Clinic of Al-Kasr AlAini Medical University Hospital, Egypt. All OA women patients were from the same socioeconomic class and lived in similar environmental conditions. Ten healthy males, ages between 20 and 30 (25.8 ± 2.1 years), were also recruited with the purpose of using them as a control. We included the same controls in an earlier study [5] for the same purposes. In principle, it was almost impossible to include in the study Egyptian ladies aged 50–60 years with no signs and completely free of osteoarthritis. Thus, there was no ‘‘age- and sex-matched controls’’ for this study group by definition. We included healthy males in the study to give the readers an idea about the normal vales of plasma 25(OH)D and NOx in our population under the conditions

123

we live, which is different from other societies. NSAIDs were used irregularly in some patients for pain relief. Exclusion criteria included smoking, chronic severe diseases such as renal failure and hepatic insufficiency which could affect the synthesis of both 25(OH)D and 1,25(OH)2D, as well as severe chronic heart failure and diabetes mellitus. Courteously, all participants were informed of the nature of the study and thus written consent that abided by the principles of the Helsinki Declaration was obtained from all of them. Approval was also obtained from the local ethics committee responsible for overseeing such studies. A fact worth mentioning is that all patients practiced the religious and cultural customs of veiling and wearing completely body-covering clothes. Diagnosis Osteoarthritis diagnosis was based on a thorough physical examination and a comprehensive patient history, which complies with previously reported methods [2, 18, 19]. Data collection Following the examination, patients were asked to fill out a questionnaire that assessed the onset of OA symptoms, absence or presence of concomitant diseases, medication used including vitamin supplements (since vitamin D supplementation was the main exclusion criterion), occupation and, finally, nutritional status or type of food in the diet. All patients reported onset of symptoms in the past 6 months and all claimed to be housewives who regularly if not daily consumed dairy products and none was vegetarian. None was taking medication capable of manipulating vitamin D status. Body mass index (BMI) calculation The patient’s weight and height were measured and their body mass indices (BMIs) calculated. Patients with BMI C25.00 kg/m2 and C30.00 kg/m2 were considered overweight and obese, respectively. Biochemical analyses: 25(OH)D and NOx determination Blood samples obtained were collected in EDTA-Eppendorf tubes and resulting plasma, after centrifugation at 2,500 rpm for 10 min at 4 °C, was preserved in a -80 °C freezer until analysis.

Aging Clin Exp Res

25(OH)D levels were analyzed by an in-house developed and validated high-performance liquid chromatography with ultraviolet detection (HPLC–UV) method after solid phase extraction of the metabolite from plasma samples. The assay is capable of detecting both forms of the metabolite, 25(OH)D2 and 25(OH)D3, giving an individualized result for each form, with excellent resolution and a limit of detection of 2 ng/mL for each metabolite. HPLC has been previously identified as the ‘‘gold standard’’ for the assessment of in vivo 25(OH)D levels. Subjects’ vitamin D status was classified into normal, having 25(OH)D concentrations C30 ng/mL, insufficient, with concentrations between 20 and 30 ng/mL, and finally deficient, with concentrations \20 ng/mL, which complied with reported reference values [4]. Nitric oxide was indirectly determined as NOx using Griess reaction, described elsewhere [20]. Briefly, plasma samples (200 lL) were deproteinated by the addition of 20 lL 30 % zinc sulfate followed by a 15 min centrifugation period at 14,000 rpm under 4 °C. 300 lL of vanadium (III) chloride (8 mg/mL) was then added to 100 lL of the supernatant to reduce nitrate to nitrite. 300 lL Griess reagent, containing 1:1 (v/v) 2 % sulfanilamide and 0.1 % N-(1-Naphthyl) ethylenediamine dihydrochloride, was then added, followed by a 30 min incubation period at 37 °C in the dark. Absorbance was determined at 540 nm and unknown concentrations were determined using the linear calibration curve constructed from serial dilutions of sodium nitrite standards (0–100 lM).

Fig. 1 Mean NOx concentrations of osteoarthritic patients and healthy participants are 32.45 ± 2.18 and 25.49 ± 2.23 lM, respectively. Significant difference existed between the means at P = 0.034

Statistical analysis Analyses were performed using GraphPad Prism statistics software (GraphPad Software, Inc. version 6.01). Means of different groups were compared using the Student’s t test. Statistical significance was accepted at P B 0.05. Results are presented as mean ± standard error of the mean (SEM), unless stated otherwise.

Fig. 2 Mean NOx concentrations of overweight (n = 15) and obese (n = 21) osteoarthritic patients are 31.32 ± 3.96 and 33.04 ± 2.53 lM, yielding an insignificant P value of 0.703

Results Mean 25(OH)D concentrations of osteoarthritic and healthy participants were 25.0 ± 1.6 and 35.4 ± 2.1 ng/mL, respectively, the comparison of which yielded a significant result (P = 0.001). The mean NOx concentrations of patients and controls are presented in Fig. 1. The mean NOx concentrations of both patients and controls complied with previously reported reference values for individuals of the same age group. However, noteworthy is that the reference values that patients were compared to were those of healthy menopausal women [21].

Fig. 3 Linear regression analysis correlating 25(OH)D levels of osteoarthritic patients with their NOx concentrations yielding a P value of 0.337 and an r2 value of 0.030

123

Aging Clin Exp Res

Fig. 4 Osteoarthritic participants exhibiting normal (n = 10), insufficient (n = 13) and deficient (n = 13) vitamin D levels yielded mean NOx concentrations of 37.83 ± 4.32, 32.52 ± 3.91 and 27.24 ± 2.80 lM, respectively. A significant difference (*) was obtained from the comparison of normal and deficient vitamin D groups (P = 0.048). Other inter-group comparisons yielded insignificant (IS) results (P [ 0.05); however, a constantly decreasing mean NOx concentration was observed with corresponding decrease in 25(OH)D reference values

Osteoarthritic patients were further classified according to their BMI into overweight and obese with the purpose of investigating the effect of BMI on circulating NOx levels. The results of this investigation are presented in Fig. 2. Perhaps, the most interesting results arose when the patients were classified according to their vitamin D status, using the reference values described earlier. Although, insignificant results were reached when all 25(OH)D and NOx values of osteoarthritic participants were taken into account (Fig. 3), mean NOx concentrations decreased with decreasing 25(OH)D reference concentrations of groups as presented in Fig. 4.

Discussion Previous studies have demonstrated an increase in serum and synovial fluid nitrate/nitrite in rheumatic disease including OA compared to controls [13, 22–24]. Our study, which includes post-menopausal Egyptian women with knee osteoarthritis, complements previous reports in this regard by demonstrating an increase in NOx in patients compared to controls (Fig. 1), as well as demonstrating similarity in NOx values obtained from our patients with those of patients of different populations. It is worth mentioning that in one of our earlier published studies [25], we reported that plasma NOx was not significantly different between healthy Egyptian males and females and not significantly affected by age.

123

To our knowledge, this is the first study to investigate this parameter in a Middle Eastern osteoarthritic population. Furthermore, the molecular or observational association of vitamin D with NO in OA has never been explored, making this the first report that attempts to do so. Another aim of the present study was to determine whether patients having different BMI values have significantly different NOx concentrations. The relationship of NOx levels with BMI has not been thoroughly studied. It has been previously reported that NOS activity and iNOS protein are abundant in human subcutaneous adipose tissue [26]. Moreover, inhibition of the NOS activity in this tissue has led to an increase in lipolysis [26]. In spite of this, the NOx–BMI relationship is subject to debate. Choi et al. [26] demonstrated a difference in NOx concentration between overweight and underweight (BMI \ 19.0 kg/m2) healthy adolescent boys and girls, yet no significant difference between underweight and healthy weight (19.0 B BMI \ 25.0 kg/m2) subjects. Contradicting results include that of Ferlito and Gallina [27] and Andersson et al. [28] where the former demonstrated that overweight diabetic patients had an insignificantly higher NO production compared to healthy controls, whereas the latter demonstrated a lack of difference in plasma nitrate concentrations between obese and non-obese post-menopausal women. This study presents an insignificant difference in NOx concentration between obese and overweight OA patients (Fig. 2), complementing previously reported studies. This result may be limited by the cohort’s size and thus studies involving larger cohorts are needed to establish the NOx– BMI relationship. Regarding the intriguing association of vitamin D with NO in OA, our study demonstrates, for the first time, an insignificant decrease in NOx concentration with decreasing 25(OH)D concentration in groups—normal, insufficient and deficient—but a significant difference in NOx concentration between the normal and deficient vitamin D groups (Fig. 4). Because of the nature of our study, a mechanistic link connecting the two investigated parameters cannot be deduced. We therefore hypothesize a number of different scenarios that may explain the observed results. Among the speculated areas of possible mechanistic overlap between vitamin D and NO in OA include modulation of NO production and iNOS expression in chondrocytes, regulation of metalloproteinase (MMP) activity and influence on proteoglycan and collagen synthesis. With respect to iNOS expression, Willems et al. [15] recently described the ability of 1,25(OH)2D3 to up-regulate the expression of iNOS and thus increase NO production in osteoblasts. Similar results were obtained by Rockett et al. [29] who described the possible positive effect of 1,25(OH)2D3 in counteracting Mycobacterium

Aging Clin Exp Res

tuberculosis by increasing NO production through stimulating iNOS expression in a macrophage-like cell line. Similarly, Molinari et al. [16] concluded that 1,25(OH)2D3 stimulated the production of NO in endothelial cells via endothelial NOS activation. On the other hand, Garcion et al. [17] illustrated the ability of 1,25(OH)2D3 to downregulate iNOS mRNA and protein expression in activated microglia, macrophages and astrocytes in rat central nervous system. The aforementioned literature illustrates the various effects vitamin D exerts on the NO system in different cell types. As previously highlighted, the effect of vitamin D on NO production and iNOS expression in chondrocytes has not been investigated. Based on the results presented in this study, we propose the effect to be a dose-dependent increase in NO production and perhaps iNOS expression complementing results of earlier studies on different cell types. Such hypothesis may seem self-contradicting on the basis that it is theorized that vitamin D’s actions in OA are strictly protective, as described elsewhere [30, 31], whereas NO is largely presented as a destructive molecule in the disease [14]. Contrary to this, recent studies have portrayed NO’s protective effects on cartilage [14]. Elucidating further, an example of contradicting studies that contribute to the controversy includes that of Pelletier et al. [32] who demonstrated that the inhibition of iNOS leads to a decrease in catabolic factors including the inflammatory mediator IL-1b and MMP, whereas recent reports have proposed that NO redox derivatives exhibit an antiinflammatory effect on chondrocytes [14]. Tetlow and Woolley [33] demonstrated the presence of VDRs in chondrocytes of osteoarthritic cartilages as opposed to that of healthy ones, as well as the simultaneous prevalence of MMPs in osteoarthritic chondrocytes suggesting a role for 1,25(OH)2D3 in MMP enzyme regulation, a notion supported by other studies. It was also shown that 1,25(OH)2D3 did not affect the production of MMP-1 and 9 by chondrocytes; however, MMP-3 production was upregulated [33]. In light of the undeniable role of NO in MMP regulation, Ridnour et al. [34] illustrated the ability of NO to modulate MMP-9 in a biphasic and flux-dependent manner where low levels of exogenous NO were shown to enhance MMP-9’s activity, activate the secreted MMP-9 at a higher stable concentration (500 nm) and finally MMP-9 inactivation at concentrations [1 mM. Our results raise the premise of vitamin D’s interaction with NO production to regulate MMP-9 activity in a manner similar to that previously described. Vitamin D has been previously shown to stimulate proteoglycan synthesis and inhibit collagenase activity [30, 31]. As expected, NO role in regulating the aforesaid activities is more complex than that of vitamin D. Hauselmann et al. [35] showed the inhibition of proteoglycan

synthesis by endogenously produced NO in both deep and superficial cartilage zones. They also showed that inhibition of NOS led to the partial and complete suppression of proteoglycan synthesis inhibition in superficial and deep zones. Moreover, increased procollagen synthesis has been shown to occur by exogenous NO administration as well as by transfection of iNOS gene into tendon cells [36]. The increase in NOx concentration with increasing 25(OH)D concentration presented in this study proposes the interaction of the two parameters to modulate proteoglycan and procollagen synthesis. We acknowledge that our study may be limited by the cohort’s size and nature. In addition, NO was not determined in the synovial fluid of the knee affected by osteoarthritis, which might have shown different levels than the blood levels. However, this study presents results leading to possible theories linking vitamin D to NO in osteoarthritis. Finally, since vitamin D may modulate pain [37], it would be of interest to see in future studies if this has any association with NO changes.

Conclusion This study proposes the influence of vitamin D in the NO system in osteoarthritic chondrocytes to be an increase in NO production as well as induction of iNOS expression, possibly leading to a protective effect. Acknowledgments The authors thank all participants recruited in this study and report no conflicts of interest in this work. Conflict of interest On behalf of all authors, the corresponding author states that there is no conflict of interest.

References 1. Felson DT, Lawrence RC, Dieppe PA et al (2000) Osteoarthritis: new insights. Part 1: the disease and its risk factors. Ann Intern Med 133:635–646 (pii:10170-00016) 2. Hinton R, Moody RL, Davis AW et al (2002) Osteoarthritis: diagnosis and therapeutic considerations. Am Fam Physician 65:841–848 3. Hochberg MCAR, April KT, Benkhalti M, Guyatt G, McGowan J, Towheed T, Welch V, Wells G, Tugwell P (2012) American College of Rheumatology 2012 recommendations for the use of nonpharmacologic and pharmacologic therapies in osteoarthritis of the hand, hip, and knee. Arthritis Care Res (Hoboken) 64:465–474 4. Holick MF (2007) Vitamin D deficiency. N Engl J Med 357:266–281. doi:10.1056/NEJMra070553 5. Abu El Maaty MA, Hanafi RS, Badawy SE et al (2013) Association of suboptimal 25-hydroxyvitamin D levels with knee osteoarthritis incidence in post-menopausal Egyptian women. Rheumatol Int 33(11):2903–2907. doi:10.1007/s00296-0122551-9

123

Aging Clin Exp Res 6. Lane NE, Gore LR, Cummings SR et al (1999) Serum vitamin D levels and incident changes of radiographic hip osteoarthritis: a longitudinal study. Study of Osteoporotic Fractures Research Group. Arthritis Rheum 42:854–860. doi:10.1002/15290131(199905)42:5\854:AID-ANR3[3.0.CO;2-I 7. Bergink AP, Uitterlinden AG, Van Leeuwen JP et al (2009) Vitamin D status, bone mineral density, and the development of radiographic osteoarthritis of the knee: the Rotterdam Study. J Clin Rheumatol 15:230–237. doi:10.1097/RHU.0b013e318 1b08f20 8. Heidari B, Heidari PHajian-Tilaki K (2011) Association between serum vitamin D deficiency and knee osteoarthritis. Int Orthop 35:1627–1631. doi:10.1007/s00264-010-1186-2 9. McAlindon TE, Felson DT, Zhang Y et al (1996) Relation of dietary intake and serum levels of vitamin D to progression of osteoarthritis of the knee among participants in the Framingham Study. Ann Intern Med 125:353–359 10. Kalichman L, Kobyliansky E (2012) Association between circulatory levels of vitamin D and radiographic hand osteoarthritis. Rheumatol Int 32:253–257. doi:10.1007/s00296-010-1741-6 11. Cao Y, Jones G, Cicuttini F et al (2012) Vitamin D supplementation in the management of knee osteoarthritis: study protocol for a randomized controlled trial. Trials 13:131. doi:10.1186/ 1745-6215-13-131 12. McAlindon TLM, Schneider E, Nuite M, Lee JY, Price LL, Lo G, Dawson-Hughes B (2013) Effect of vitamin D supplementation on progression of knee pain and cartilage volume loss in patients with symptomatic osteoarthritis: a randomized controlled trial. JAMA 309:155–162 13. Farrell AJ, Blake DR, Palmer RM et al (1992) Increased concentrations of nitrite in synovial fluid and serum samples suggest increased nitric oxide synthesis in rheumatic diseases. Ann Rheum Dis 51:1219–1222 14. Abramson SB (2008) Osteoarthritis and nitric oxide. Osteoarthr Cartil 16(Suppl 2):S15–S20. doi:10.1016/S1063-4584(08) 60008-4 15. Willems HM, van den Heuvel EG, Carmeliet G et al (2012) VDR dependent and independent effects of 1,25-dihydroxyvitamin D3 on nitric oxide production by osteoblasts. Steroids 77:126–131. doi:10.1016/j.steroids.2011.10.015 16. Molinari C, Uberti F, Grossini E et al (2011) 1 alpha, 25-dihydroxycholecalciferol induces nitric oxide production in cultured endothelial cells. Cell Physiol Biochem 27:661–668. doi:10.1159/ 000330075 17. Garcion E, Nataf S, Berod A et al (1997) 1,25-Dihydroxyvitamin D3 inhibits the expression of inducible nitric oxide synthase in rat central nervous system during experimental allergic encephalomyelitis. Brain Res Mol Brain Res 45:255–267 (pii:S01693 28X96002604) 18. Zhang W, Doherty M, Peat G et al (2010) EULAR evidencebased recommendations for the diagnosis of knee osteoarthritis. Ann Rheum Dis 69:483–489. doi:10.1136/ard.2009.113100 19. Bierma-Zeinstra SM, Oster JD, Bernsen RM et al (2002) Joint space narrowing and relationship with symptoms and signs in adults consulting for hip pain in primary care. J Rheumatol 29:1713–1718 20. Bryan NS, Grisham MB (2007) Methods to detect nitric oxide and its metabolites in biological samples. Free Radic Biol Med 43:645–657. doi:10.1016/j.freeradbiomed.2007.04.026 21. Ghasemi A, Zahediasl S, Azizi F (2010) Reference values for serum nitric oxide metabolites in an adult population. Clin Biochem 43:89–94. doi:10.1016/j.clinbiochem.2009.09.011

123

22. Pham TN, Rahman P, Tobin YM et al (2003) Elevated serum nitric oxide levels in patients with inflammatory arthritis associated with co-expression of inducible nitric oxide synthase and protein kinase C-eta in peripheral blood monocyte-derived macrophages. J Rheumatol 30:2529–2534 (pii:0315162X-30-2529) 23. Ersoy Y, Ozerol E, Baysal O et al (2002) Serum nitrate and nitrite levels in patients with rheumatoid arthritis, ankylosing spondylitis, and osteoarthritis. Ann Rheum Dis 61:76–78 24. Karan A, Karan MA, Vural P et al (2003) Synovial fluid nitric oxide levels in patients with knee osteoarthritis. Clin Rheumatol 22:397–399. doi:10.1007/s10067-003-0761-y 25. Gad MZ, Abdel Rahman MF, Hashad IM et al (2012) Endothelial nitric oxide synthase (G894T) gene polymorphism in a random sample of the Egyptian population: comparison with myocardial infarction patients. Genet Test Mol Biomarkers 16:695–700. doi:10.1089/gtmb.2011.0342 26. Choi JW, Pai SH, Kim SK et al (2001) Increases in nitric oxide concentrations correlate strongly with body fat in obese humans. Clin Chem 47:1106–1109 27. Ferlito S, Gallina M (1999) Nitrite plasma levels in type 1 and 2 diabetics with and without complications. Minerva Endocrinol 24:117–121 28. Andersson B, Wikstrand J, Ljung T et al (1998) Urinary albumin excretion and heart rate variability in obese women. Int J Obes Relat Metab Disord 22:399–405 29. Rockett KA, Brookes R, Udalova I et al (1998) 1,25-Dihydroxyvitamin D3 induces nitric oxide synthase and suppresses growth of Mycobacterium tuberculosis in a human macrophagelike cell line. Infect Immun 66:5314–5321 30. Corvol MT, Dumontier MF, Tsagris L et al (1981) Cartilage and vitamin D in vitro (author’s transl). Ann Endocrinol (Paris) 42:482–487 31. Dean DD, Boyan BD, Schwart Z et al (2001) Effect of 1 alpha, 25-dihydroxyvitamin D3 and 24R,25-dihydroxyvitamin D3 on metalloproteinase activity and cell maturation in growth plate cartilage in vivo. Endocrine 14:311–323 ENDO:14:3:311 [pii] 32. Pelletier JP, Lascau-Coman V, Jovanovic D et al (1999) Selective inhibition of inducible nitric oxide synthase in experimental osteoarthritis is associated with reduction in tissue levels of catabolic factors. J Rheumatol 26:2002–2014 33. Tetlow LC, Woolley DE (2001) Expression of vitamin D receptors and matrix metalloproteinases in osteoarthritic cartilage and human articular chondrocytes in vitro. Osteoarthr Cartil 9:423–431. doi:10.1053/joca.2000.0408 34. Ridnour LA, Windhausen AN, Isenberg JS et al (2007) Nitric oxide regulates matrix metalloproteinase-9 activity by guanylylcyclase-dependent and -independent pathways. Proc Natl Acad Sci USA 104:16898–16903. doi:10.1073/pnas.0702761104 35. Hauselmann HJ, Stefanovic-Racic M, Michel BA et al (1998) Differences in nitric oxide production by superficial and deep human articular chondrocytes: implications for proteoglycan turnover in inflammatory joint diseases. J Immunol 160:1444–1448 36. Xia W, Szomor Z, Wang Y et al (2006) Nitric oxide enhances collagen synthesis in cultured human tendon cells. J Orthop Res 24:159–172. doi:10.1002/jor.20060 37. Laslett LL Quinn S, Burgess JR, Parameswaran V, Winzenberg TM, Jones G, Ding C (2013) Moderate vitamin D deficiency is associated with changes in knee and hip pain in older adults: a 5-year longitudinal study. Ann Rheum Dis. doi:10.1136/ annrheumdis-2012-202831

Interplay of vitamin D and nitric oxide in post-menopausal knee osteoarthritis.

Mounting evidence has presented nitric oxide (NO) and vitamin D (vitD) as having independently complex roles in osteoarthritis (OA). However, a mechan...
256KB Sizes 0 Downloads 0 Views