Biology subjects

Obeidat, A. M.

Publications and source records attributed to Obeidat, A. M..

4 recordsLinked to original sources

bioRxiv2023

Recommendations For a Standardized Approach to Histopathologic Evaluation of Synovial Membrane in Murine Models of Experimental Osteoarthritis

BackgroundSynovial pathology has been linked to osteoarthritis (OA) pain in patients. Microscopic grading systems for synovial changes in human OA have been described, but a standardized approach for murine models of OA is needed. We sought to develop a reproducible approach and set of minimum recommendations for synovial histopathology in mouse models of OA. MethodsCoronal and sagittal sections from male mouse knee joints subjected to destabilization of medial meniscus (DMM) or partial meniscectomy (PMX) were collected as part of other studies. Stains included Hematoxylin and Eosin (H&E), Toluidine Blue (T- Blue) and Safranin O/Fast Green (Saf-O). Four blinded readers graded pathological features (hyperplasia, cellularity, and fibrosis) at specific anatomic locations in the medial and lateral compartments. Inter-reader reliability of each feature was determined. ResultsThere was acceptable to very good agreement between raters. After DMM, increased hyperplasia and cellularity and a trend towards increased fibrosis were observed 6 weeks after DMM in the medial locations, and persisted up to 16 weeks. In the PMX model, cellularity and hyperplasia were evident in both medial and lateral compartments while fibrotic changes were largely seen on the medial side. Synovial changes were consistent from section to section in the mid-joint area mice. H&E, T-blue, and Saf-O stains resulted in comparable reliability. ConclusionsTo allow for a standard evaluation that can be implemented and compared across labs and studies, we recommend using 3 readers to evaluate a minimum set of 3 pathological features at standardized anatomic areas. Pre-defining areas to be scored, and reliability for each pathologic feature should be considered.

pathology↗

bioRxiv2023

Intra-Articular Sprouting Of Nociceptors Accompanies Progressive Osteoarthritis: Comparative Evidence In Four Murine Models

ObjectiveKnee joints are densely innervated by nociceptors. Sprouting of nociceptors has been reported in late-stage osteoarthritis (OA), both in human knees and in rodent models. Here, we sought to describe progressive nociceptor remodeling in four mouse models of knee OA, capturing early and late-stage disease. MethodsSham surgery, destabilization of the medial meniscus (DMM), partial meniscectomy (PMX), or non-invasive anterior cruciate ligament rupture (ACLR) was performed in the right knee of 10-12-week old male C57BL/6 NaV1.8-tdTomato mice. Mice were euthanized (1) 4, 8 or 16 weeks after DMM or sham surgery; (2) 4 or 12 weeks after PMX or sham; (3) 1 or 4 weeks after ACLR injury or sham. Additionally, a cohort of naive male wildtype mice was evaluated at 6 and 24 months. Twenty-m thick mid-joint cryosections were assessed qualitatively and quantitatively for NaV1.8+ and PGP9.5+ innervation. Cartilage damage (using a modified OARSI score), synovitis, and osteophytes were assessed blindly. ResultsProgressive OA developed in the medial compartment after DMM, PMX, and ACLR. Synovitis and associated neo-innervation by nociceptors peaked in early-stage OA. In the subchondral bone, channels containing sprouting nociceptors appeared early, and progressed with worsening joint damage. Two-year old mice developed primary OA in both the medial and the lateral compartment, accompanied with neuroplasticity in the synovium and the subchondral bone. All 4 models had an increased nerve signal in osteophytes. ConclusionAnatomical neuroplasticity of nociceptors was observed in association with joint damage in 4 distinct mouse models, suggesting that it is intrinsic to OA pathology.

neuroscience↗

bioRxiv2022

Sexual dimorphism of the synovial transcriptome underpins greater PTOA disease severity in male mice following joint injury

ObjectiveTo elucidate sex differences in synovitis, mechanical sensitization, structural damage, bone remodeling, and the synovial transcriptome in the anterior cruciate ligament rupture (ACLR) mouse model of post-traumatic osteoarthritis (PTOA). MethodsMale and female 12-week-old C57Bl/6 mice were randomized to noninvasive ACLR or sham (n=9/sex/group/timepoint). Knee hyperalgesia, mechanical allodynia, and intra-articular MMP activity (via intravital imaging) were measured longitudinally. Trabecular and subchondral bone remodeling and osteophyte formation were assessed by CT. Histological scoring of PTOA and synovitis and anti-MMP13 immunostaining was performed. NaV1.8-Cre;tdTomato mice were used to document localization and sprouting of nociceptors. Bulk RNAseq of synovium in sham, 7d, and 28d post-ACLR, and contralateral joints (n=6) assessed injury-induced and sex-dependent synovial gene expression. ResultsMale mice exhibited worse joint damage at 7d and 28d and worse synovitis at 28d, accompanied by greater MMP activity, knee hyperalgesia, and mechanical allodynia. Females had catabolic responses in trabecular and subchondral bone after injury, whereas males exhibited greater osteophyte formation and sclerotic remodeling of trabecular and subchondral bone. NaV1.8+ nociceptor sprouting in subchondral bone and medial synovium was induced by injury and comparable between sexes. RNAseq of synovium demonstrated that both sexes had similar injury-induced gene expression at 7d, but only female mice exhibited synovial inflammatory resolution by 28d, whereas males had persistent pro-inflammatory, pro-fibrotic, pro-neurogenic, and pro-angiogenic gene expression. ConclusionWorse overall joint pathology and pain behavior in male mice was associated with persistent activation of synovial inflammatory, fibrotic, and neuroangiogenic processes, implicating persistent synovitis in driving sex differences in murine PTOA.

physiology↗

bioRxiv2022

Piezo2 expressing nociceptors mediate mechanical sensitization in experimental osteoarthritis

Osteoarthritis is a very common painful joint disease, for which few treatment options exist. New non-opioid targets are needed for addressing osteoarthritis pain, which is mechanical in nature and associated with daily activities such as walking and climbing stairs. Piezo2 has been implicated in development of mechanical pain, but the mechanisms by which this occurs remain poorly understood. We observed that in two different murine models of osteoarthritis (destabilization of the medial meniscus and natural aging), nociceptor-specific Piezo2 conditional knock-out mice developed osteoarthritic joint damage, but were protected from associated mechanical sensitization. Since nerve growth factor (NGF) is known to mediate nociceptor sensitization, and antibodies that neutralize NGF are effective as a treatment for osteoarthritis pain, we explored the effects of intra-articularly injected NGF on the development of mechanical joint pain. Wild-type mice developed knee swelling and mechanical pain in response to intra-articular NGF, while nociceptor-specific Piezo2 conditional knock-out mice were protected from these effects. Single cell RNA sequencing and in situ hybridization of mouse and human lumbar dorsal root ganglia (DRG) revealed that a subset of nociceptors co-express Piezo2 and Ntrk1 (the gene that encodes the NGF receptor TrkA). These results indicate that Piezo2 plays a key role in nociceptor sensitization processes in the osteoarthritic joint, and targeting Piezo2 may represent a novel therapy for osteoarthritis pain control. One Sentence SummaryNociceptor sensitization to mechanical stimuli is dependent on Piezo2 in mouse models of osteoarthritis.

physiology↗