Testing mechanisms and clinical outcomes of synovial fibrosis in total knee arthroplasty patients
Location
Medical Education Building, LSUHSC-NO
Presentation Date
10-10-2019 10:00 AM
End Date
10-10-2019 12:00 PM
Description
Osteoarthritis is the leading cause of physical disability among Americans over 65 years old. Among patients with osteoarthritis, black patients are more likely to report higher levels of pain, loss of function, and lower quality of life compared to white patients. This disparity has been documented both nationwide1 and in our cohort of 154 patients in New Orleans. Additionally, we have observed within this cohort, black patients are more likely to present with high levels of synovial fibrosis prior to total knee arthroplasty (TKA) when compared to white patients. Determining the clinical significance of synovial fibrosis and the molecular pathways that lead to synovial fibrosis could provide targets to improve one aspect of the disparity we observe in our patient population. Therefore, this study aims to investigate two questions: 1) what is the clinical significance of increased synovial fibrosis in our patient population? and 2) what molecular pathways lead to increased pre-operative synovial fibrosis? 1) There is evidence that synovial fibrosis, or the increased deposition of collagen 1 in the synovial membrane, contributes to joint stiffness in the hip and following ACL repair surgeries2,3. We therefore hypothesize that patients with greater collagen deposition in the knee synovium prior to surgery will exhibit reduced knee movement as a result of fibrosis compared to patients who present with lower levels of collagen 1 in the synovium. To test this hypothesis, we collected the synovium of patients undergoing TKA. Of the patients enrolled in the study, 61 had both flexion and extension range of motion measurements for the affected knee recorded prior to surgery. We measured the amount of collagen deposition in the synovium of these patients via picrosirius red staining and ran a Spearman correlation analysis with the range of motion. We found a significant negative correlation (R=-0.57, p<0.0001) of collagen density with range of motion; suggesting patients with increased synovial fibrosis as a result of collagen 1 experience higher stiffness. 2) To identify potential factors involved in the development of synovial fibrosis, we measured serum levels of 19 factors known to be involved in OA progression using a multiplex immunoassay on 40 patients undergoing TKA. We found two circulating cytokines: IL6 and IL13 are increased in patients with high fibrosis. IL13 has been implicated in the development of fibrotic diseases such as systemic sclerosis and promotes fibrosis through a pathway independent of TGFb14,5. To determine if IL13 could directly contribute to a fibrotic phenotype in OA synoviocytes, we isolated synoviocytes from 10 patients undergoing TKA and treated the cells with exogenous IL13. To quantify a fibrotic phenotype, we analyzed changes in the expression levels of Collagen1A1 (COL1A1) and the matrix degradation enzyme MMP9 via quantitative PCR. We found that patient variability in response to IL13 treatments was quite high. In 5 out of 10 of the lines tested, synoviocytes showed an increase in COL1A1 and a decrease in MMP9 expression in response to IL13 treatment compared to baseline expression. In the other lines, we observed no change or slight decreases in COL1A1 expression and no change or increases in MMP9 expression. When accounting for race and fibrotic state of the patient, we did not observe a pattern of response. These results suggest cells from different patients may be primed to respond to the same cytokine in different ways. Although we cannot conclude if IL13 is able to promote a fibrotic phenotype in synoviocytes, these studies do highlight how prevalent intrinsic cellular differences are among patients. Future studies will involve investigating a panel of factors in the synovial tissue that are involved in fibrosis to determine if these factors can predict patient outcomes following TKA. Particularly, we will follow up with the hypothesis that certain patients have a set of factors in the synovial tissue that “primes” them for fibrosis. We will focus on Il-6, Il-1α, TGF-B, which are all involved in the inflammatory process. We will also follow up with other factors from the multiplex immunoassay to investigate if there are differences in levels among patients and if those differences contribute to fibrosis. We will aim to increase our sample size in subsequent experiments, assess other clinical factors, and investigate if factors such as race, gender, and BMI are correlated to fibrosis.
Recommended Citation
Saunee, Lauren A.; Valentino, John; McCarthy, Christina; and Plakotaris, Elena, "Testing mechanisms and clinical outcomes of synovial fibrosis in total knee arthroplasty patients" (2019). Medical Student Research Poster Symposium. 37.
https://digitalscholar.lsuhsc.edu/sommrd/2019/posters/37
Testing mechanisms and clinical outcomes of synovial fibrosis in total knee arthroplasty patients
Medical Education Building, LSUHSC-NO
Osteoarthritis is the leading cause of physical disability among Americans over 65 years old. Among patients with osteoarthritis, black patients are more likely to report higher levels of pain, loss of function, and lower quality of life compared to white patients. This disparity has been documented both nationwide1 and in our cohort of 154 patients in New Orleans. Additionally, we have observed within this cohort, black patients are more likely to present with high levels of synovial fibrosis prior to total knee arthroplasty (TKA) when compared to white patients. Determining the clinical significance of synovial fibrosis and the molecular pathways that lead to synovial fibrosis could provide targets to improve one aspect of the disparity we observe in our patient population. Therefore, this study aims to investigate two questions: 1) what is the clinical significance of increased synovial fibrosis in our patient population? and 2) what molecular pathways lead to increased pre-operative synovial fibrosis? 1) There is evidence that synovial fibrosis, or the increased deposition of collagen 1 in the synovial membrane, contributes to joint stiffness in the hip and following ACL repair surgeries2,3. We therefore hypothesize that patients with greater collagen deposition in the knee synovium prior to surgery will exhibit reduced knee movement as a result of fibrosis compared to patients who present with lower levels of collagen 1 in the synovium. To test this hypothesis, we collected the synovium of patients undergoing TKA. Of the patients enrolled in the study, 61 had both flexion and extension range of motion measurements for the affected knee recorded prior to surgery. We measured the amount of collagen deposition in the synovium of these patients via picrosirius red staining and ran a Spearman correlation analysis with the range of motion. We found a significant negative correlation (R=-0.57, p<0.0001) of collagen density with range of motion; suggesting patients with increased synovial fibrosis as a result of collagen 1 experience higher stiffness. 2) To identify potential factors involved in the development of synovial fibrosis, we measured serum levels of 19 factors known to be involved in OA progression using a multiplex immunoassay on 40 patients undergoing TKA. We found two circulating cytokines: IL6 and IL13 are increased in patients with high fibrosis. IL13 has been implicated in the development of fibrotic diseases such as systemic sclerosis and promotes fibrosis through a pathway independent of TGFb14,5. To determine if IL13 could directly contribute to a fibrotic phenotype in OA synoviocytes, we isolated synoviocytes from 10 patients undergoing TKA and treated the cells with exogenous IL13. To quantify a fibrotic phenotype, we analyzed changes in the expression levels of Collagen1A1 (COL1A1) and the matrix degradation enzyme MMP9 via quantitative PCR. We found that patient variability in response to IL13 treatments was quite high. In 5 out of 10 of the lines tested, synoviocytes showed an increase in COL1A1 and a decrease in MMP9 expression in response to IL13 treatment compared to baseline expression. In the other lines, we observed no change or slight decreases in COL1A1 expression and no change or increases in MMP9 expression. When accounting for race and fibrotic state of the patient, we did not observe a pattern of response. These results suggest cells from different patients may be primed to respond to the same cytokine in different ways. Although we cannot conclude if IL13 is able to promote a fibrotic phenotype in synoviocytes, these studies do highlight how prevalent intrinsic cellular differences are among patients. Future studies will involve investigating a panel of factors in the synovial tissue that are involved in fibrosis to determine if these factors can predict patient outcomes following TKA. Particularly, we will follow up with the hypothesis that certain patients have a set of factors in the synovial tissue that “primes” them for fibrosis. We will focus on Il-6, Il-1α, TGF-B, which are all involved in the inflammatory process. We will also follow up with other factors from the multiplex immunoassay to investigate if there are differences in levels among patients and if those differences contribute to fibrosis. We will aim to increase our sample size in subsequent experiments, assess other clinical factors, and investigate if factors such as race, gender, and BMI are correlated to fibrosis.
Comments
Mentor: Jennifer Simkin, PhD