Magnoflorine Alleviates “M1” Polarized Macrophage-Induced Intervertebral Disc Degeneration Through Repressing the HMGB1/Myd88/NF-κB Pathway and NLRP3 Inflammasome

Abstract

Intervertebral disc degeneration (IDD) is related to the deterioration of nucleus pulposus (NP) cells due to hypertrophic differentiation and calcification. The imbalance of pro-inflammatory (M1 type) and anti-inflammatory (M2 type) macrophages contributes to maintaining tissue integrity. Here, we aimed to probe the effect of Magnoflorine (MAG) on NP cell apoptosis mediated by “M1” polarized macrophages. THP-1 cells were treated with lipopolysaccharide (LPS) to induce “M1” polarized macrophages. Under the treatment with increasing concentrations of MAG, the expression of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-18), high mobility group box protein 1 (HMGB1), as well as myeloid differentiation factor 88 (MyD88), nuclear factor kappa B (NF-κB) and NOD-like receptor 3 (NLRP3) inflammasomes in THP-1 cells were determined. What’s more, human NP cells were treated with the conditioned medium (CM) from THP-1 cells. The NP cell viability and apoptosis were evaluated. Western blot (WB) was adopted to monitor the expression of apoptosis-related proteins (Bax, Caspase3, and Caspase9), catabolic enzymes (MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5), and extracellular matrix (ECM) compositions (collagen II and aggrecan) in NP cells. As a result, LPS evidently promoted the expression of pro-inflammatory cytokines and HMGB1, the MyD88-NF-κB activation, and the NLRP3 inflammasome profile in THP-1 cells, while MAG obviously inhibited the "M1″ polarization of THP-1 cells. After treatment with “M1” polarized THP-1 cell CM, NP cell viability was decreased, while cell apoptosis, the pro-inflammatory cytokines, apoptosis-related proteins, and catabolic enzymes were distinctly up-regulated, and ECM compositions were reduced. After treatment with MAG, NP cell damages were dramatically eased. Furthermore, MAG dampened the HMGB1 expression and inactivated the MyD88/NF-κB pathway and NLRP3 inflammasome in NP cells. In conclusion, this study confirmed that MAG alleviates “M1” polarized macrophage-mediated NP cell damage by inactivating the HMGB1-MyD88-NF-κB pathway and NLRP3 inflammasome, which provides a new reference for IDD treatment.

Macrophage polarization regulates intervertebral disc degeneration by modulating cell proliferation, inflammation mediator secretion, and extracellular matrix metabolism

“…However, previous studies often tested in the inflammatory environment, which probably induce macrophage polarization and make the results ambiguous in some extend. A recent study by Li et al revealed M1 macrophage polarization induced IDD (29), and M2a macrophages promote ECM metabolic imbalances in rat IDD (30). Nonetheless, the spectrums of macrophages that mimic actual environment of IDD are lacking.…”

α‐Mangostin protects lipopolysaccharide‐stimulated nucleus pulposus cells against NLRP3 inflammasome‐mediated apoptosis via the NF‐κB pathway

“…NLRP3 inflammasome has been found to be implicated in multiple inflammatory diseases, including Alzheimer's disease, atherosclerosis, diabetes, and various infectious diseases . Hence, targeting the NLRP3 (Zhao et al, 2021). Moreover, it has been reported that α-mangostin has the ability to regulate NLRP3 inflammasome activity.…”

“…Morin was shown to attenuate pyroptosis of NPCs and ameliorate IDD via inhibiting the NLRP3/caspase‐1/IL‐1β signaling pathway (Zhou et al, 2021). Additionally, magnoflorine was reported to alleviate IDD progression through inhibiting inflammation, cell apoptosis, and matrix degradation via repressing NLRP3 inflammasome activity (Zhao et al, 2021). Moreover, it has been reported that α‐mangostin has the ability to regulate NLRP3 inflammasome activity.…”

Relationships between serum HMGB1 concentration and subpopulation composition of circulating monocytes in patients with subclinical atherosclerosis

“…На экспериментальной модели аутоиммунного миокардита также было установлено репрограммирование клеток в сторону М1-макрофагов путем активации пути TLR4-PI3Kγ-Erk1/2 под действием HMGB1 [26]. Ингибирование HMGB1 в свою очередь способно снизить количество провоспалительных макрофагов [12,38]. Все это может свидетельствовать в пользу того, что HMGB1 является одним из каузальных факторов обнаруженных нами изменений в субпопуляционном составе моноцитов.…”