Peniocerol normalizes ECM markers and inhibits MMP3 in IL-1β/TNF-α inflamed meniscal cells

Osteoarthritis (OA) is a debilitating joint disease characterized by cartilage degeneration, meniscal damage, and chronic inflammation. Current treatments often focus on symptom management rather than disease modification, leaving a critical gap for therapies that address both meniscal health and OA progression. Inflammatory cytokines like IL-1β and TNF-α are known drivers of this degeneration, activating pathways such as NF-κB, which upregulates catabolic enzymes like MMP13 and downregulates anabolic markers like COL2A1. Developing novel agents that can counteract these inflammatory and degenerative processes is crucial for comprehensive OA treatment.

Researchers investigated the effects of peniocerol (PEN) on human meniscal fibrochondrocyte cells. Cells were isolated, cultured, and initially treated with varying PEN concentrations to determine cell proliferation and IC₅₀ via MTT assay. Subsequently, cells were stimulated with TNF-α (10 ng/mL) or IL-1β (5 ng/mL) to induce inflammation, either alone or co-treated with PEN (300 and 500 µM). Cell morphology and the expression of key markers including ACAN, type I+III collagen, type II collagen, MMP13, and p65 (a subunit of NF-κB) were evaluated using immunofluorescence to assess the degenerative phenotype and PEN's restorative effects.

Inflammatory stimulation with TNF-α and IL-1β significantly reduced the expression of ACAN and type II collagen, while increasing MMP13 and p65, indicating a clear degenerative phenotype in the fibrochondrocytes. Co-treatment with PEN at 300 µM showed partial improvements in these markers. However, the higher concentration of PEN at 500 µM demonstrated a more pronounced effect.

PEN at 500 µM normalized the levels of ACAN, Col2A1 (type II collagen), and p65 to values similar to the control, while significantly inhibiting the markers for COL I+III and MMP3. This suggests that peniocerol effectively mitigated the inflammatory cascade and its downstream effects on extracellular matrix degradation. The normalization of p65 expression further supports PEN's role in modulating the NF-κB signaling pathway, which is central to the inflammatory response in OA.