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Dynamic biophysical strain modulates proinflammatory gene induction in meniscal fibrochondrocytes.

ABSTRACT: Fibrochondrocytes of meniscus adapt to changes in their biomechanical environment by mechanisms that are yet to be elucidated. In this study, the mechanoresponsiveness of fibrochondrocytes under normal and inflammatory conditions was investigated. Fibrochondrocytes from rat meniscus were exposed to dynamic tensile forces (DTF) at various magnitudes and frequencies. The mechanoresponsiveness was assessed by examining the expression of inducible nitric oxide synthase (iNOS), tumor necrosis factor-alpha (TNF-alpha), and matrix metalloproteinase-13 mRNA expression. The mRNA and protein analyses revealed that DTF at magnitudes of 5% to 20% did not induce proinflammatory gene expression. IL-1beta induced a rapid increase in the iNOS mRNA. DTF strongly repressed IL-1beta-dependent iNOS induction in a magnitude-dependent manner. Exposure to 15% DTF resulted in >90% suppression of IL-1beta-induced mRNA within 4 h and this suppression was sustained for the ensuing 20 h. The mechanosensitivity of fibrochondrocytes was also frequency dependent and maximal suppression of iNOS mRNA expression was observed at rapid frequencies of DTF compared with lower frequencies. Like iNOS, DTF also inhibited IL-1beta-induced expression of proinflammatory mediators involved in joint inflammation. The examination of temporal effects of DTF revealed that 4- or 8-h exposure of DTF was sufficient for its sustained anti-inflammatory effects during the next 20 or 16 h, respectively. Our findings indicate that mechanical signals act as potent anti-inflammatory signals, where their magnitude and frequency are critical determinants of their actions. Furthermore, mechanical signals continue attenuating proinflammatory gene transcription for prolonged periods of time after their removal.

SUBMITTER: Ferretti M

PROVIDER: S-EPMC4950929 | biostudies-literature | 2006 Jun

REPOSITORIES: biostudies-literature

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Dynamic biophysical strain modulates proinflammatory gene induction in meniscal fibrochondrocytes.

Ferretti Mario M Madhavan Shashi S Deschner James J Rath-Deschner Birgit B Wypasek Ewa E Agarwal Sudha S

American journal of physiology. Cell physiology 20060201 6

Fibrochondrocytes of meniscus adapt to changes in their biomechanical environment by mechanisms that are yet to be elucidated. In this study, the mechanoresponsiveness of fibrochondrocytes under normal and inflammatory conditions was investigated. Fibrochondrocytes from rat meniscus were exposed to dynamic tensile forces (DTF) at various magnitudes and frequencies. The mechanoresponsiveness was assessed by examining the expression of inducible nitric oxide synthase (iNOS), tumor necrosis factor- ...[more]

PMID: 16452158

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Project description:Menisci play a vital role in load transmission, shock absorption and joint stability. The current dogma is that the menisci simply protects the cartilage and play no role in osteoarthritis (OA) unless they are injured. However, there is increasing evidence suggesting that OA menisci may not merely be bystanders in the disease process of OA. This study sought: 1) to determine the prevalence of meniscal degeneration in OA patients, 2) to examine gene expression in OA meniscal cells compared to normal control meniscal cells, and 3) to test the hypothesis that OA meniscal cells are different from normal meniscal cells. The grades of meniscal degeneration correlated in a positive fashion with the grades of articular cartilage degeneration (r = 0.672; P < 0.0001). Many genes classified in the biological processes of immune response, inflammatory response, biomineral formation and cell proliferation, including major histocompatibility complex, class II, DP alpha 1 (HLA-DPA1), integrin, beta 2 (ITGB2), ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), ankylosis, progressive homolog (ANKH) and fibroblast growth factor 7 (FGF7), were expressed at higher levels compared to normal control meniscal cells. In addition, many genes that were previously implicated in OA were also expressed at higher levels in OA meniscal cells, including ADAM metallopeptidase with thrombospondin type 1 motif, 5 (ADAMTS5). Our findings suggest that OA is a whole joint disease. Meniscal cells may play an active role in the development of OA. Investigation of the gene expression profiles of OA meniscal cells may reveal new therapeutic targets for OA therapy and also may uncover novel disease markers for early diagnosis of OA. Studies were approved by our human subjects Institutional Review Board. Menisci and articular cartilage were collected during joint replacement surgery for OA patients (OA specimens) and lower limb amputation surgery for osteosarcoma patients (normal control specimens), and graded. Meniscal cells were prepared from the meniscal tissues and expanded in monolayer culture. Differential gene expression in OA meniscal cells and normal control meniscal cells was examined using Affymetrix microarray and real time RT-PCR.

Project description:BackgroundMenisci play a vital role in load transmission, shock absorption and joint stability. There is increasing evidence suggesting that OA menisci may not merely be bystanders in the disease process of OA. This study sought: 1) to determine the prevalence of meniscal degeneration in OA patients, and 2) to examine gene expression in OA meniscal cells compared to normal meniscal cells.MethodsStudies were approved by our human subjects Institutional Review Board. Menisci and articular cartilage were collected during joint replacement surgery for OA patients and lower limb amputation surgery for osteosarcoma patients (normal control specimens), and graded. Meniscal cells were prepared from these meniscal tissues and expanded in monolayer culture. Differential gene expression in OA meniscal cells and normal meniscal cells was examined using Affymetrix microarray and real time RT-PCR.ResultsThe grades of meniscal degeneration correlated with the grades of articular cartilage degeneration (r = 0.672; P < 0.0001). Many of the genes classified in the biological processes of immune response, inflammatory response, biomineral formation and cell proliferation, including major histocompatibility complex, class II, DP alpha 1 (HLA-DPA1), integrin, beta 2 (ITGB2), ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), ankylosis, progressive homolog (ANKH) and fibroblast growth factor 7 (FGF7), were expressed at significantly higher levels in OA meniscal cells compared to normal meniscal cells. Importantly, many of the genes that have been shown to be differentially expressed in other OA cell types/tissues, including ADAM metallopeptidase with thrombospondin type 1 motif 5 (ADAMTS5) and prostaglandin E synthase (PTGES), were found to be expressed at significantly higher levels in OA meniscal cells. This consistency suggests that many of the genes detected in our study are disease-specific.ConclusionOur findings suggest that OA is a whole joint disease. Meniscal cells may play an active role in the development of OA. Investigation of the gene expression profiles of OA meniscal cells may reveal new therapeutic targets for OA therapy and also may uncover novel disease markers for early diagnosis of OA.

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Dynamic biophysical strain modulates proinflammatory gene induction in meniscal fibrochondrocytes.

Publications

Dynamic biophysical strain modulates proinflammatory gene induction in meniscal fibrochondrocytes.

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