Title: LOXL2 Maintain and Protect TMJ-OA Cartilage in Vivo
Mustafa Tashkandi (Presenter)
Boston University Henry M. Goldman School of Dental Medicine
Thabet Alhousami, Boston University Henry M. Goldman School of Dental Medicine
Pushkar Mehra, Boston University
Larry Wolford, Baylor University Medical Center
Louis Gerstenfeld, Boston University
Mary Goldring, Weill Cornell Medical College
Manish Bais, Boston University Henry M. Goldman School of Dental Medicine
Objectives: LOXL2 is expressed in the OA lesions of the human knee joint cartilage (1) and in regenerating mouse cartilage (2), and it is critical for chondrogenic differentiation (3). The objective of this study is to evalute if LOXL2 could have role in vivo human and mice TMJ cartilage affected by OA.
Methods: All experiments were performed with approval of Institutional Review Board (IRB) and Institutional Animal Care and Use Committee (IACUC). Adenoviral-LOXL2 (Adv-LOXL2) injected weekly into TMJ-OA cartilage/matrigel implants in nude mice for 6 weeks; total RNA was isolated from HAC-OA implants and subjected to RNAseq (Illumina500, Illumina, Inc) with 24 million reads per sample. Human TMJ-OA tissues were subjected to immunofluorescence analysis.
Results: Adv-LOXL2 local delivery to TMJ-OA implants in nude mice increases expression of genes related to the chondrogenic lineage (ACAN, SOX9, DLX5, DLX6) or ECM (FMOD, BGN, COL11A1) (Figure 4), but attenuates NFKB1, WNT11, and myogenic lineage genes (MEF2C, NEB, MYH1 and TTN) compared to control. Gene set enrichment analysis showed that Adv-LOXL2 treated implants are enriched with reactome ECM organization, collagen formation, keratan sulfate, dermatan sulfate, chondroitin sulfate biosynthesis whereas myogenesis and VEGF signaling networks are downregulated. Next to evaluate if elevated level of LOXL2 in degenerative lesions has co-expression with agents expressed in human TMJ-OA, the immunofluorescence analysis showed that TGF-β1 co-expresses in same layers with LOXL2, whereas TNF-α and IL-1β expressed in different layers than LOXL2 in clinical TMJ-OA. LOXL2 is up-regulated in damaged joints similar to other anabolic factors such as BMP2 , FGF18 , IGF1, and TGFβ1, compared to non-affected cartilage. Finally, we are evaluating the effect of LOXL2 in collagen type XI chondrodysplasia (Cho+/-) mice.
Conclusions: LOXL2 treatment maintains and promotes chondrogenesis, whereas in the absence of LOXL2 treatment, chondrogenic genes are inhibited, and myogenic gene network lineage is promoted.
Acknowledgements: NIH/NIDCR (R03DE025274) to Manish V. Bais.
1. Alshenibr, W., Bais, M. V. (2017) Arthritis Res Ther 19, 179
2. Bais, M., (2009) et al. PloS one 4, e5393
3. Iftikhar, M., et al The Journal of biological chemistry 286, 909-918