NF-kappa B as a target for anti-inflammatory gene therapy: suppression of inflammatory responses in monocytic and stromal cells by stable gene transfer of I kappa B alpha cDNA.

One of the most challenging issues of anti-inflammatory gene therapy is the complexity of inflammatory pathways. Transcription factor NF-kappa B plays a pivotal role in activation of multiple inflammatory molecules, and therefore represents the logical target for intervention. We evaluated the feasibility of suppressing the inflammatory responses in different cell lines through specific inhibition of NF-kappa B by gene transfer of I kappa B alpha, the naturally occurring intracellular inhibitor of NF-kappa B. The I kappa B alpha overexpressing cells were established using retroviral gene transfer or stable transfection with the wild-type (wt) I kappa B alpha cDNA. In all cell types, overexpression of wt I kappa B alpha resulted in a profound (> 100-fold) increase of the I kappa B alpha message and a moderate (two- to three-fold) increase of the I kappa B alpha protein. The effects of the I kappa B alpha overexpression on the NF-kappa B activation and the inflammatory responses varied significantly in different cell lines. In conditionally immortalized human endometrial stromal cells, overexpression of I kappa B alpha prevented both interleukin-1 (IL-1)-inducible degradation of endogenous I kappa B alpha protein and activation of NF-kappa B. Accordingly, induction of cytokines interleukin-8 (IL-8) and Gro gamma was markedly suppressed. In monocytic THP-1 cells, both lipopolysaccharide (LPS)-inducible degradation of I kappa B alpha and NF-kappa B activation were only partially inhibited by overexpression of exogenous I kappa B alpha cDNA. None the less, the LPS-induced transcription of IL-1 beta and secretion of cytokines interleukin-6 (IL-6) and IL-8 were virtually abolished. In epithelial HT-29 cells, no inflammatory responses were inhibited. These results demonstrate the range of responses in various cell lines to gene transfer of I kappa B alpha and indicate the feasibility of suppression of inflammatory responses in appropriate target cells and their progeny by suppression of NF-kappa B.