Nanoparticle-based inhibition of vascular endothelial growth factor receptors alleviates osteoarthritis pain and cartilage damage.

Osteoarthritis (OA) is characterized by cartilage damage, inflammation, and pain. Vascular endothelial growth factor receptors (VEGFRs) have been associated with OA severity, suggesting that inhibitors targeting these receptors alleviate pain (via VEGFR1) or cartilage degeneration (via VEGFR2). We have developed a nanoparticle-based formulation of pazopanib (Votrient), an FDA-approved anticancer drug that targets both VEGFR1 and VEGFR2 (Nano-PAZII). We demonstrate that a single intraarticular injection of Nano-PAZII can effectively reduce joint pain for a prolonged time without substantial side effects in two different preclinical OA rodent models involving either surgical (upon partial medial meniscectomy) or nonsurgical induction (with monoiodoacetate). The injection of Nano-PAZII blocks VEGFR1 and relieves OA pain by suppressing sensory neuronal ingrowth into the knee synovium and neuronal plasticity in the dorsal root ganglia and spinal cord. Simultaneously, the inhibition of VEGFR2 reduces cartilage degeneration. These findings provide a mechanism-based disease-modifying drug strategy that addresses both pain symptoms and cartilage loss in OA.

Repurposing Mitomycin C in Combination with Pentamidine or Gentamicin to Treat Infections with Multi-Drug-Resistant (MDR) Pseudomonas aeruginosa.

The aims of this study were (i) to determine if the combination of mitomycin C with pentamidine or existing antibiotics resulted in enhanced efficacy versus infections with MDR P. aeruginosa in vivo; and (ii) to determine if the doses of mitomycin C and pentamidine in combination can be reduced to levels that are non-toxic in humans but still retain antibacterial activity. Resistant clinical isolates of P. aeruginosa, a mutant strain over-expressing the MexAB-OprM resistance nodulation division (RND) efflux pump and a strain with three RND pumps deleted, were used. MIC assays indicated that all strains were sensitive to mitomycin C, but deletion of three RND pumps resulted in hypersensitivity and over-expression of MexAB-OprM caused some resistance. These results imply that mitomycin C is a substrate of the RND efflux pumps. Mitomycin C monotherapy successfully treated infected Galleria mellonella larvae, albeit at doses too high for human administration. Checkerboard and time-kill assays showed that the combination of mitomycin C with pentamidine, or the antibiotic gentamicin, resulted in synergistic inhibition of most P. aeruginosa strains in vitro. In vivo, administration of a combination therapy of mitomycin C with pentamidine, or gentamicin, to G. mellonella larvae infected with P. aeruginosa resulted in enhanced efficacy compared with monotherapies for the majority of MDR clinical isolates. Notably, the therapeutic benefit conferred by the combination therapy occurred with doses of mitomycin C close to those used in human medicine. Thus, repurposing mitomycin C in combination therapies to target MDR P. aeruginosa infections merits further investigation.

Loss of PKCδ/Prkcd prevents cartilage degeneration in joints but exacerbates hyperalgesia in an experimental osteoarthritis mouse model.

Pain is the prime symptom of osteoarthritis (OA) that directly affects the quality of life. Protein kinase Cδ (PKCδ/Prkcd) plays a critical role in OA pathogenesis; however, its significance in OA-related pain is not entirely understood. The present study investigated the functional role of PKCδ in OA pain sensation. OA was surgically induced in control (Prkcdfl/fl), global- (Prkcdfl/fl; ROSACreERT2), and sensory neuron-specific conditional knockout (cKO) mice (Prkcdfl/fl; NaV1.8/Scn10aCreERT2) followed by comprehensive analysis of longitudinal behavioral pain, histopathology and immunofluorescence studies. GlobalPrkcd cKO mice prevented cartilage deterioration by inhibiting matrix metalloproteinase-13 (MMP13) in joint tissues but significantly increased OA pain. Sensory neuron-specificdeletion of Prkcd in mice did not protect cartilage from degeneration but worsened OA-associated pain. Exacerbated pain sensitivity observed in global- and sensory neuron-specific cKO of Prkcd was corroborated with markedly increased specific pain mediators in knee synovium and dorsal root ganglia (DRG). These specific pain markers include nerve growth factor (NGF) and vascular endothelial growth factor (VEGF), and their cognate receptors, including tropomyosin receptor kinase A (TrkA) and vascular endothelial growth factor receptor-1 (VEGFR1). The increased levels of NGF/TrkA and VEGF/VEGFR1 were comparable in both global- and sensory neuron-specific cKO groups. These data suggest that the absence of Prkcd gene expression in the sensory neurons is strongly associated with OA hyperalgesia independent of cartilage protection. Thus, inhibition of PKCδ may be beneficial for cartilage homeostasis but could aggravate OA-related pain symptoms.