*Article* **Identification of Novel Targets of Knee Osteoarthritis Shared by Cartilage and Synovial Tissue**

**Chenshuang Li <sup>1</sup> and Zhong Zheng 2,\***


**\*** Correspondence: zzheng@dentistry.ucla.edu; Tel.: +1-(310)-206-5646

Received: 5 August 2020; Accepted: 19 August 2020; Published: 22 August 2020

**Abstract:** Arthritis is the leading cause of disability among adults, while osteoarthritis (OA) is the most common form of arthritis that results in cartilage loss. However, accumulating evidence suggests that the protective hyaline cartilage should not be the sole focus of OA treatment. Particularly, synovium also plays essential roles in OA's initiation and progression and warrants serious consideration when battling against OA. Thus, biomarkers with similar OA-responsive expressions in cartilage and synovium should be the potential targets for OA treatment. On the other hand, molecules with a distinguished response during OA in cartilage and synovium should be ruled out as OA therapeutic(s) to avoid controversial effects in different tissues. Here, to pave the path for developing a new generation of OA therapeutics, two published transcriptome datasets of knee articular cartilage and synovium were analyzed in-depth. Genes with statistically significantly different expression in OA and healthy cartilage were compared with those in the synovium. Thirty-five genes with similar OA-responsive expression in both tissues were identified while recognizing three genes with opposite OA-responsive alteration trends in cartilage and synovium. These genes were clustered based on the currently available knowledge, and the potential impacts of these clusters in OA were explored.

**Keywords:** osteoarthritis; cartilage; synovium; whole transcriptome sequencing; biomarker
