Browsing by Author "Sinclair, Steven Michael"

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Open Access
Attenuation of inflammatory events in human intervertebral disc cells with a tumor necrosis factor antagonist.
(2010) Sinclair, Steven Michael
STUDY DESIGN: The inflammatory responses of primary human intervertebral disc (IVD) cells to tumor necrosis factor α (TNF-α) and an antagonist were evaluated in vitro. OBJECTIVE: To investigate an ability for soluble TNF receptor type II (sTNFRII) to antagonize TNF-α-induced inflammatory events in primary human IVD cells in vitro. SUMMARY OF BACKGROUND DATA: TNF-α is a known mediator of inflammation and pain associated with radiculopathy and IVD degeneration. sTNFRs and their analogues are of interest for the clinical treatment of these IVD pathologies, although information on the effects of sTNFR on human IVD cells remains unknown. METHODS: IVD cells were isolated from surgical tissues procured from 15 patients and cultured with or without 1.4 nmol/L TNF-α (25 ng/mL). Treatment groups were coincubated with varying doses of sTNFRII (12.5-100 nmol/L). Nitric oxide (NO), prostaglandin E₂ (PGE₂), and interleukin-6 (IL6) levels in media were quantified to characterize the inflammatory phenotype of the IVD cells. RESULTS: Across all patients, TNF-α induced large, statistically significant increases in NO, PGE₂, and IL6 secretion from IVD cells compared with controls (60-, 112-, and 4-fold increases, respectively; P < 0.0001). Coincubation of TNF-α with nanomolar doses of sTNFRII significantly attenuated the secretion of NO and PGE₂ in a dose-dependent manner, whereas IL6 levels were unchanged. Mean IC₅₀ values for NO and PGE₂ were found to be 35.1 and 20.5 nmol/L, respectively. CONCLUSION: Nanomolar concentrations of sTNFRII were able to significantly attenuate the effects of TNF-α on primary human IVD cells in vitro. These results suggest this sTNFR to be a potent TNF antagonist with potential to attenuate inflammation in IVD pathology.
Open Access
Development of Depot Forming Elastin-Like Polypeptide-Curcumin Drug Conjugates for Sustained Drug Delivery to Treat Neuroinflammatory Pathologies
(2013) Sinclair, Steven Michael
Neuroinflammation associated with lumbar radiculopathy and peripheral nerve injury is characterized by locally increased levels of the pro-inflammatory cytokine tumor necrosis factor alpha (TNFα). Systemic administration of TNF antagonists for radiculopathy in the clinic has shown mixed results, and there is growing interest in local delivery of anti-inflammatory drugs to treat this pathology, as well as similar inflammatory events of peripheral nerve injury. Curcumin, a known antagonist of TNFα in multiple cell types and tissues, was chemically modified and conjugated to a thermally responsive elastin-like polypeptide (ELP) to create an injectable depot for sustained, local delivery of curcumin to treat neuroinflammation.
ELPs are biopolymers capable of thermally-triggered in situ depot formation and have been successfully employed as drug carriers and biomaterials in several applications. A library of ELP-curcumin conjugates were synthesized and characterized. One lead conjugate was shown to display high drug loading, rapidly release curcumin in vitro via degradable carbamate bonds, and retain in vitro bioactivity against TNFα and NF-κB with near-equivalent potency compared to free curcumin. When injected into the perineural space via intramuscular (i.m.) injection proximal to the sciatic nerve in mice, ELP-curcumin conjugates underwent a thermally triggered soluble-insoluble phase transition, leading to in situ formation of a depot that released curcumin over 4 days post-injection and decreased systemic exposure of curcumin 3-fold.
The results of this dissertation support the use of ELP as a drug carrier for local perineural drug delivery, and the strategy presented here for drug conjugate development and use of depot-forming ELP-curcumin conjugates represents a novel means of providing sustained treatment of neuroinflammation and pain associated with radiculopathy and peripheral nerve injury.