Accepted

Lornoxicam (LRX) is a potent nonsteroidal anti-inflammatory drug (NSAID) used extensively to manage pain and inflammatory conditions. However, the drug possesses poor aqueous solubility (i.e., BCS class II) and a short half-life (3-4h). Mucoadhesive buccal tablets containing LRX -loaded solid lipid nanoparticles (SLNs) were developed to enhance the drug solubility and bioavailability and achieve a controlled release pattern for a better anti-inflammatory effect. Different LRX-loaded SLNs were prepared using the hot homogenization /ultra-sonication technique and evaluated using size analysis and entrapment efficiency (EE%). Optimized LRX -loaded SLNs formulation showed particle size of 216± 7.4 nm, zeta potential of -27.3±4.6 mV, and entrapment efficiency of 92.56± 2.3 %. Dried LRX-loaded SLNs alongside mucoadhesive polymers blend (PVP K30 /HPMC K15) were compressed to prepare the mucoadhesive buccal tablets. The tablets showed proper physicochemical properties, good mucoadhesive strength, long mucoadhesive time, suitable pH surface, good swelling capacity, and controlled drug release profile. Furthermore, Fourier transform-infrared (FTIR) spectroscopy, Powder X-Ray diffraction (PXRD), and Scanning electron microscopy (SEM) studies were carried out. The in vivo anti-inflammatory effect of pure LRX, market LRX and optimized mucoadhesive buccal tablet of LRX -loaded SLNs (T3) against carrageenan-induced models were evaluated. T3 showed a significant and early anti-inflammatory response after 1 and 2 h (63.62 – 77.84 % inhibition) as well as an extended effect after 4 h as compared to pure and market LRX. In parallel, T3 showed the best amelioration of PGE2, COX2, and TNF-α serum levels after 4 h of carrageenan injection.

Maresin-2 (MaR2) is a specialized pro-resolution lipid mediator (SPM) that reduces neutrophil recruitment in zymosan peritonitis. Here, we investigated the analgesic effect of MaR2 and its mechanisms in different mouse models of pain. For that, we used the lipopolysaccharide (LPS)-induced mechanical hyperalgesia (electronic version of the von Frey filaments), thermal hyperalgesia (hot plate test) and weight distribution (static weight bearing), as well as the spontaneous pain models induced by capsaicin (TRPV1 agonist) or AITC (TRPA1 agonist). Immune cell recruitment was determined by immunofluorescence and flow cytometry while changes in the pro-inflammatory mediator landscape were determined using a proteome profiler kit and ELISA after LPS injection. MaR2 treatment was also performed in cultured DRG neurons stimulated with capsaicin or AITC in the presence or absence of LPS. The effect of MaR2 on TRVP1- and TRPA1-dependent CGRP release by cultured DRG neurons was determined by EIA. MaR2 inhibited LPS-induced inflammatory pain and changes in the cytokine landscape as per cytokine array assay. MaR2 also inhibited TRPV1 and TRPA1 activation as observed by a reduction in calcium influx in cultured DRG neurons, and the number of flinches and time spent licking the paw induced by capsaicin or AITC. In corroboration, MaR2 reduced capsaicin- and AITC-induced CGRP release by cultured DRG neurons and immune cell recruitment to the paw skin close the CGRP fibers. In conclusion, we show that MaR2 is an analgesic SPM that acts by targeting leukocyte recruitment, nociceptor TRPV1 and TRPA1 activation, and CGRP release in mice.

The astrocytes-secreted active molecule, Hevin considerably contributes in the transsynaptic bridge of neurexin1β/neuligin1 in excitatory synapse. Previous studies have demonstrated that activity-dependent synaptic recruitment of spinal neuroligin1 and GluA1-containing AMPA receptors (AMPARs) is involved in incisional, inflammatory and neuropathic pain. Here, we hypothesized that Hevin induced postoperative pain hypersensitivity by enhancing the neurexin1β/neuroligin1-mediated synaptic targeting of GluA1-containing AMPARs in spinal dorsal horns (DH). Our results showed that plantar incision induced significant postoperative pain behavior, which was described by the cumulative pain scores. At 1 d and 3 d post-incision, Hevin expression was considerably elevated in ipsilateral DHs, although it recovered to baseline value at 5 d following the incision. At 1 d post plantar incision, the neurexin1β/neuroligin1 interactions significantly increased in ipsilateral DHs in rats subjected to incision when compared with those in control rats. Intrathecal pretreatments of small interference RNA targeting Hevin substantially suppressed postoperative pain hypersensitivity and reduced the neurexin1β/neurolgin1 interaction as well as the synaptic targeting of GluA1 in ipsilateral spinal DHs. These data suggest that Hevin induced postoperative pain hypersensitivity by enhancing the neurexin1β/neuroligin1 interaction and subsequent synaptic targeting of GluA1-containing AMPARs in ipsilateral spinal DHs. It provides new insights into the role of Hevin-mediated trans-synaptic regulation in postoperative pain hypersensitivity, which would help develop a novel therapeutic strategy.