Treatment with Encapsulated Hsp60 Peptide (p277) Prolongs Skin Graft Survival in a Murine Model of Minor Antigen Disparity

Abstract

The increased expression of heat shock protein (Hsp)60 in different kinds of graft tissues has been associated with a proinflammatory role and rejection. However, there are very few reports in which treatment with Hsp60 delays skin allograft rejection. The aim of this work was to evaluate the capacity of encapsulated human Hsp60‐derived peptide p277 to delay graft rejection in two murine models of skin transplantation with minor antigen disparities. Briefly, BALB/c mice and C57BL/6 were intranasally pre‐treated with five doses of Hsp60 p277 peptide encapsulated in polylactide‐co‐glycolide acid microspheres (PLGM), and received skin grafts from DBA2 mice and 129/B6 (F1) mice respectively. The treatment with the peptide increased skin graft survival more than 20 days in both the mouse strains, mainly in C57BL/6 recipients (P < 0.05). Also, p277‐treated BALB/c and C57BL/6 mice showed IL‐10 and IFN‐γ production, induced by p277 peptide. For the first time, a mucosal schedule using the Hsp60 C‐terminal peptide p277 encapsulated in PLGM showed some survival prolongation of skin grafts bearing minor antigen disparities. Our results suggest a potential role for Hsp60‐based therapy and the mucosal route as a useful tool to control the inflammatory response to allografts.

Danger signals in regulating the immune response to solid organ transplantation

“…HSPs have been proposed as resolution-associated molecular patterns that induce the production of immunoregulatory cytokines such as IL-10 to mitigate further tissue damage (51). Consistent with this idea, studies in skin transplant models have demonstrated that elevated HSP expression increases IL-10 levels and Treg recruitment, and prolongs allograft survival (52)(53)(54). These studies emphasize that the impact of HSP expression on the subsequent alloimmune response is likely to be highly context-specific and possibly even organ-specific.…”

HSP60: Issues and Insights on Its Therapeutic Use as an Immunoregulatory Agent

“…Nonetheless, our group has been investing on the identification of potent HSP60 immunoregulatory peptides for use in allotransplantation. We have been able to prolong allograft survival across both minor (Luna et al, 2007) and major (unpublished data from V. Coelho laboratory) alloantigen disparities but so far, we have been unsuccessful in inducing transplantation tolerance. Nevertheless, other investigators have been able to induce transplantation tolerance in a mouse model of skin allograft (Birk et al, 1999), but publications in this field are scarcer.…”

“…Regulatory elements triggered by nasal versus oral administration of antigen may be distinct but both routes have been described as efficient ways to modulate inflammatory diseases by HSP60, including reducing atherosclerotic plaque formation in the Ldlr−/− mice (Maron et al, 2002) and prolonging allograft survival in mice (Luna et al, 2007). We would like to point that other forms of continuous delivery of HSP60 have been explored with success.…”

“…We would like to point that other forms of continuous delivery of HSP60 have been explored with success. Accordingly, intranasal administration of HSP60 peptide p277 encapsulated into polylactide-co-glycolide acid microspheres resulted in increased skin graft survival in two combinations of murine strains with minor H-2 disparities (Luna et al, 2007). …”

“…However, we believe this issue will only be clearly solved when HSP60 produced in endotoxin-free systems is used for functional assays. Taking this into consideration, as well as HSP60 REG/INFLAMMA properties, several groups and ours have been exploring the immunologic functions of HSP60 synthetic peptides in a variety of pathological and physiological (Prakken et al, 1997; Luna et al, 2007) contexts, and have identified immunologically active peptides, effective in, at least partially, downregulating inflammation in animal models (Elias et al, 1991; Thompson et al, 1998; Luna et al, 2007) and in humans in the context of diabetes (Raz et al, 2001, 2007). …”