Genetically engineered bacteria expressing –Melanocyte–stimulating hormone (–MSH) as an inhibitor of traumatic ocular inflammatory reaction in rats

Abstract

Abstract: : Purpose: α–Melanocyte–stimulating hormone (α–MSH) is an endogenous neuroimmunomodulatory peptide that inhibits all major forms of experimental inflammation. A new technology has been developed which uses probiotic yeast and bacteria as vehicles to deliver therapeutic proteins into the human body. We studied whether genetically engineered bacteria (Lactobacillus casei) expressing α–Melanocyte–stimulating hormone (α–MSH) can reduce inflammatory reactions after induced ocular trauma in rats. Methods: Sixty rats (Wistar), equally divided into three groups each received a corneolimbal incision, followed by paracentesis and aspiration of the aqueous humor. The experimental group received a single topical application of genetically engineered bacteria expressing α–MSH, and the control groups received topical application of α–MSH, and Balanced Salt Solution as positive and negative control respectively. Twenty–four hours later, protein levels were measured and the total number of inflammatory cells was counted in the aqueous humor. Clinical inflammation was graded by observation of conjunctival hyperemia, edema, and corneal damage. Results: Topical lactic acid bacteria (LAB) expressing α–MSH reduced clinical inflammation, protein levels, and the total number of inflammatory cells in the aqueous humor (p<0.01). Conclusions: The results suggest that a single topical application of genetically engineered bacteria expressing α–MSH could be useful for the control of acute ocular inflammatory reactions, thus reducing the frequency of instillation and increasing patient compliance.

Keywords: drug toxicity/drug effects • gene/expression • inflammation