Affiliations: Department of Dermatology, Kinki University School of Medicine, 377‐2 Ohno‐Higashi, Osaka‐Sayama, Osaka 589‐8511, Japan | Research and Development, Du Pont Merck, P.O.Box 80336, Wilmington, DE 19880‐0336, USA | Institute for Health Sciences, Tokushima Bunri University, Yamashiro, Tokushima, Tokushima 770‐8514, Japan
Abstract: The inhibitory properties of phosphorylated cystatin \alpha (P‐cystatin \alpha) and a conjugated protein of the P‐cystatin \alpha with filaggrin linker segment peptide (FLSP) against the growth of Staphylococcus bacteria and poliovirus were investigated. Both the P‐cystatin \alpha and the conjugated protein (P‐cystatin \alpha‐FLSP conjugate) as a model for the cornified envelope of skin inhibited the cysteine protease activity of Staphylococcus aureus V8. The protease activity was inhibited by normal cornified envelope of newborn rat skin, which contains P‐cystatin \alpha, and P‐cystatin \alpha in cornified envelope of newborn rat skin also suppressed the growth of S. aureus V8. When P‐cystatin \alpha or P‐cystatin \alpha‐FLSP conjugate was added to cultured HeLa cells infected with poliovirus, 50–70% of the cell‐death due to poliovirus infection was prevented. The poliovirus 3C protease activity in the infected HeLa cells was inhibited by P‐cystatin \alpha or P‐cystatin \alpha‐FLSP conjugate. As a result, the processing of viral capsid peptides was suppressed. These findings suggest that P‐cystatin \alpha and P‐cystatin \alpha‐FLSP conjugate could play the role of the barrier against microorganism infections due to inhibition of their cysteine protease activities.
