DiaPep277 peptide therapy in the context of other immune intervention trials in type 1 diabetes

Novel mutant P277 peptide VP to ameliorate atherogenic side-effects and to preserve anti-diabetic effects in NOD mice

P277 is a 24 amino-acids peptide, residues 437-460 of human heat shock protein 60 (HSP60). P277 or sequence repeated 6 × P277 was previously found showing potency preventive and therapeutic anti-diabetes functions in NOD mice, but aroused atherosclerosis due to the induction of anti-HSP65 autoantibodies as reported. To determine the intrinsic B epitope sequence, we screened P277 with pepscan method and then proved by detection of sera IgG from peptide fragments vaccinated mouse and rabbits. Results indicated HSP60 443-448 (ALLRCI) is potential intrinsic B epitope sequence of P277. We modified P277 by deleting the former three amino acids of ALLRCI (VP) or replacing these six with alanine (AP). The detection of serum lipid parameter in NOD mice and aorta endothelial damage levels in high-cholesterol diets fed rabbits demonstrated that VP induced higher anti-diabetes efficacy and caused less arteriosclerosis-liked diseases separately. With less TLR2/4 activation of dendritic cells and macrophages, VP treatment reduced Th1 related P277 specific pro-inflammatory cytokines production and increased regulatory immune responses both in vivo and in vitro. These results indicated that optimized VP peptide might serve as a promising candidate for mouse type 1 diabetes therapy.

Extracellular cell stress (heat shock) proteins-immune responses and disease: an overview

Extracellular cell stress proteins are highly conserved phylogenetically and have been shown to act as powerful signalling agonists and receptors for selected ligands in several different settings. They also act as immunostimulatory 'danger signals' for the innate and adaptive immune systems. Other studies have shown that cell stress proteins and the induction of immune reactivity to self-cell stress proteins can attenuate disease processes. Some proteins (e.g. Hsp60, Hsp70, gp96) exhibit both inflammatory and anti-inflammatory properties, depending on the context in which they encounter responding immune cells. The burgeoning literature reporting the presence of stress proteins in a range of biological fluids in healthy individuals/non-diseased settings, the association of extracellular stress protein levels with a plethora of clinical and pathological conditions and the selective expression of a membrane form of Hsp70 on cancer cells now supports the concept that extracellular cell stress proteins are involved in maintaining/regulating organismal homeostasis and in disease processes and phenotype. Cell stress proteins, therefore, form a biologically complex extracellular cell stress protein network having diverse biological, homeostatic and immunomodulatory properties, the understanding of which offers exciting opportunities for delivering novel approaches to predict, identify, diagnose, manage and treat disease.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.

Promotion of atherosclerosis in high cholesterol diet-fed rabbits by immunization with the P277 peptide

Previous evidence has proved the ability of immunization with heat shock protein (HSP) 60/65 to induce atherosclerosis. P277, a 24-residue peptide of human HSP60, is a promising peptide vaccine against autoimmune diabetes. But as a fragment of HSP60, its potential ability of promoting atherosclerosis has never been investigated yet. In the present study, the rabbits fed with normal standard diet or high cholesterol diet were immunized with P277 or PBS emulsified in incomplete Freund's adjuvant 4 times at 4-week intervals. Atherosclerotic lesions of the rabbits receiving P277 treatment and fed with high cholesterol diet increased significantly compared with those of the rabbits receiving PBS treatment and the same diet. However, no obvious lesions were found in the two groups of rabbits fed with the normal standard diet. Significant expression of P277 was detected in the high cholesterol diet-induced atherosclerotic lesions and heat-stressed endothelial cells. Surface exposure of P277 was also observed in the stressed cells. In the subsequent assay of endothelial cells in vitro, the purified anti-P277 antibodies mediated a noticeable cytotoxicity to the stressed cells with the participation of complement. In conclusion, subcutaneous immunization with P277 emulsified in IFA can aggravate the atherosclerosis in high cholesterol diet-fed rabbits. Surface expression of P277 was observed on stressed endothelial cells, and were suggested to mediate the autoimmune attack and promote the disease.

The potential role of dendritic cells in the therapy of Type 1 diabetes

Type 1 diabetes (T1D) is the result of T-cell mediated autoimmune destruction of pancreatic islet β-cells. The two current treatments for T1D are based on insulin or islet-cell replacement rather than the pathogenesis of T1D and remain problematic. Islet/pancreas transplantation does not cater for the majority of sufferers due to the lack of supply of organs and the need for continuous immunosuppression regimens. The mainstay treatment is insulin replacement, but this is disruptive to lifestyle and does not protect against severe long-term complications. An early vaccination and long-term restoration of immune tolerance to self-antigens in T1D patients (reversing the immunopathogenesis of the disease) would be preferable. Dendritic cells (DCs) are potent APCs and play an important role in inducing and maintaining immune tolerance. Targeting DCs through different DC surface molecules shows effective modulation of immune responses. Their feasibility for immunotherapy to prolong transplant survival and cancer immunotherapy has been demonstrated. Therefore, DCs could potentially be used in the treatment of autoimmune diseases. This review summarizes new insights into DCs as a potential therapeutic target for the treatment of T1D.

Hsp60 chaperonopathies and chaperonotherapy: targets and agents

INTRODUCTION

Hsp60 (Cpn60) assembles into a tetradecamer that interacts with the co-chaperonin Hsp10 (Cpn10) to assist client polypeptides to fold, but it also has other roles, including participation in pathogenic mechanisms.

AREA COVERED

Hsp60 chaperonopathies are pathological conditions, inherited or acquired, in which the chaperone plays a determinant etiologic-pathogenic role. These diseases justify selection of Hsp60 as a target for developing agents that interfere with its pathogenic effects. We provide information on how to proceed.

EXPERT OPINION

The information available encourages the development of ways to improve Hsp60 activity (positive chaperonotherapy) when deficient or to block it (negative chaperonotherapy) when pathogenic. Many questions are still unanswered and obstacles are obvious. More information is needed to establish when and why autologous Hsp60 becomes a pathogenic autoantigen, or induces cytokine formation and inflammation, or favors carcinogenesis. Clarification of these points will take considerable time. However, analysis of the Hsp60 molecule and a search for active compounds aimed at structural sites that will affect its functioning should continue without interruption. No doubt that some of these compounds will offer therapeutic hopes and will also be instrumental for dissecting structure-function relationships at the biochemical and biological (using animal models and cultured cells) levels.

Treg inducing adjuvants for therapeutic vaccination against chronic inflammatory diseases

Many existing therapies in autoimmune diseases are based on systemic suppression of inflammation and the observed side effects of these therapies illustrate the pressing need for more specific interventions. Regulatory T-cells (Treg) are pivotal controllers of (auto-aggressive) immune responses and inflammation, and decreased Treg numbers and/or functioning have been associated with autoimmune disease. Therefore, Treg became frequently studied targets for more specific immunotherapy. Especially antigen-specific targeting of Treg would enable local and tailor made interventions, while obviating the negative side effect of general immuno-suppression. Self-antigens that participate in inflammation, irrespective of the etiology of the different autoimmune diseases, are held to be candidate antigens for antigen-specific interventions. Rather than tolerance induction to disease inciting self-antigens, which are frequently unknown, general self-antigens expressed at sites of inflammation would allow targeting of disease independent, but inflammatory-site specific, regulatory mechanisms. Preferably, such self-antigens should be abundantly expressed and up-regulated at the inflammatory-site. In this perspective heat shock proteins (Hsp) have several characteristics that make them highly attractive targets for antigen-specific Treg inducing therapy. The development of an antigen-specific Treg inducing vaccine is a major novel goal in the field of immunotherapy in autoimmune diseases. However, progress is hampered not only by the lack of effective antigens, but also by the fact that other factors such as dose, route, and the presence or absence of an adjuvant, turned out to be critical unknowns, with respect to the effective induction of Treg. In addition, the use of a Treg inducing adjuvant might be required to achieve an effective regulatory response, in the case of ongoing inflammation. Future goals in clinical trials will be the optimization of natural Treg expansion (or the induction of adaptive Treg) without loss of their suppressive function or the concomitant induction of non-regulatory T-cells. Here, we will discuss the potential use of protein/peptide-based vaccines combined with Treg inducing adjuvants for the development of therapeutic vaccines against chronic inflammatory conditions.

Coevolution analyses illuminate the dependencies between amino acid sites in the chaperonin system GroES-L

BACKGROUND

GroESL is a heat-shock protein ubiquitous in bacteria and eukaryotic organelles. This evolutionarily conserved protein is involved in the folding of a wide variety of other proteins in the cytosol, being essential to the cell. The folding activity proceeds through strong conformational changes mediated by the co-chaperonin GroES and ATP. Functions alternative to folding have been previously described for GroEL in different bacterial groups, supporting enormous functional and structural plasticity for this molecule and the existence of a hidden combinatorial code in the protein sequence enabling such functions. Describing this plasticity can shed light on the functional diversity of GroEL. We hypothesize that different overlapping sets of amino acids coevolve within GroEL, GroES and between both these proteins. Shifts in these coevolutionary relationships may inevitably lead to evolution of alternative functions.

RESULTS

We conducted the first coevolution analyses in an extensive bacterial phylogeny, revealing complex networks of evolutionary dependencies between residues in GroESL. These networks differed among bacterial groups and involved amino acid sites with functional importance and others with previously unsuspected functional potential. Coevolutionary networks formed statistically independent units among bacterial groups and map to structurally continuous regions in the protein, suggesting their functional link. Sites involved in coevolution fell within narrow structural regions, supporting dynamic combinatorial functional links involving similar protein domains. Moreover, coevolving sites within a bacterial group mapped to regions previously identified as involved in folding-unrelated functions, and thus, coevolution may mediate alternative functions.

CONCLUSIONS

Our results highlight the evolutionary plasticity of GroEL across the entire bacterial phylogeny. Evidence on the functional importance of coevolving sites illuminates the as yet unappreciated functional diversity of proteins.

Peptide-based approaches to treat lupus and other autoimmune diseases

After a long period where the potential of therapeutic peptides was let into oblivion and even dismissed, there is a revival of interest in peptides as potential drug candidates. Novel strategies for limiting metabolism and improve their bioavailability, and alternative routes of administration have emerged. This resulted in a large number of peptide-based drugs that are now being marketed in different indications. Regarding autoimmunity, successful data have been reported in numerous mouse models of autoimmune inflammation, yet relatively few clinical trials based on synthetic peptides are currently underway. This review reports on peptides that show much promises in appropriate mouse models of autoimmunity and describes in more detail clinical trials based on peptides for treating autoimmune patients. A particular emphasis is given to the 21-mer peptide P140/Lupuzor that has completed successfully phase I, phase IIa and phase IIb clinical trials for systemic lupus erythematosus.