Short summary

Novel study regarding the immunosuppressive effects of a peptide derived from an endogenous retroviral protein in immune cells isolated in blood samples from Crohn's disease patients. Will the peptide be able to lower ex-vivo IL-6 expression?

Rationale

The following proposal concerns the study of a putative advantageous role of a peptide derived from an endogenous retroviral envelope protein in inflammatory bowel disease (IBD). The Envelope 59 is a HERV-H derived envelope protein and is one of only three to constitute a complete open reading frame among over 100 HERV-H derived sequences in the human genome. Genetics, functional expression, and immunological lines of evidence suggest a role for this protein in controlling the adverse effects associated with Systemic Lupus Erythematous (SLE).

Based on that finding an anti-inflammatory peptide was synthesized and shown to have a protective effect in a murine rheumatoid arthritis (RA) model. Furthermore, the peptide can modulate the inflammatory state of cells isolated from blood samples from SLE and RA patients.

We now want to investigate if a similar effect can be exerted on cells isolated from blood samples obtained from IBD patients.

Retroviruses have been repeatedly discussed as etiological factors of autoimmune rheumatic diseases including SLE and RA and antibodies to gag and env regions of retroviruses, including Human Endogenous Retroviruses (HERVs), have been reported in patients with autoimmune disease, but the role of retroviruses in these diseases remains unclear.

Patients with rheumatoid arthritis (RA) are positive for HTLV-1 p19 and p24 antigens but, intriguingly, no antibodies to HTLV-1 are detected in the sera.

Other studies revealed that SLE patients make antibodies to p24 gag of HIV-1 and anti-SM (anti-smith) antibody can cross-react with p24 gag.

Moreover, HRES-1 (Human T-cell lymphotropic virus-related endogenous sequence) is a HERV sequence expressed in higher quantities in patients with varying autoimmune disease than healthy controls (8,9).

Given the autoimmune nature of the diseases and of IBD, we hypothesize that HERVs could also be involved in IBD pathogenesis - thus the interest in this study to evaluate findings in patients with Crohn's disease.

In our studies with SLE patients we have found that there is a significant upregulation of an endogenous HERV derived envelope gene in patients with SLE compared to healthy controls. This gene encodes a protein that is transported to the cell surface and thus is available for interaction with the cells of the immune system. Those results corroborate the possibility that HERVs could be potentially assembled into infectious virions through pseudotyping with virion proteins encoded by different HERVs or exogenous counterparts.

In our studies, we found a negative correlation between the expression levels of Env59 and IL-6 and TLR7 molecules. IL-6 is believed to be a critical modulator in various inflammatory diseases with a broad range of activities on diverse target cells.

In the early phase of infectious inflammation, IL-6 is produced by monocytes and macrophages immediately after stimulation of Toll-like receptors e.g. TLR-7 with distinct pathogen-associated molecular patterns (PAMPs). Elevated levels of IL6 have been found in patients with various inflammatory and autoimmune diseases and blocking the IL-6 receptor has been shown to have beneficial effect in all models of lupus tested to date.

Furthermore, anti-IL6-receptormAb treatment has been reported to be effective in clinical trials including RA and juvenile idiopathic arthritis and is now used as a standard treatment regimen. IL-6 signaling has also been suggested to be of importance in the immunopathogenesis of IBD, however, no effect of anti-IL6-receptor treatment has been documented in these patients.

We have further shown that a peptide derived from the Env59 protein exhibited an anti-inflammatory effect. We have shown in vitro that a peptide derived from the immune suppressive domain of an endogenous retrovirus diminishes production of IL-6 in stimulated human PBMCs obtained from patients with SLE and RA.

Furthermore, the peptide had a beneficial effect on the development of disease in a murine animal model of RA and multiple sclerosis.

Aim:

The immunosuppressive peptide derived from HERV-H env59 is capable of lowering ex-vivo IL-6 expression in immune cells isolated in blood samples from Crohn's disease patients ex vivo.

Description of the cohort

A: Up to 20 patients with active Crohn's disease.

B: Up to 20 patients with Crohn's disease in remission.

C: Up to 20 healthy controls

Data and biological material

Blood samples - 24 ml pr patient.

Collaborating researchers and departments

Department of Molecular Medicine, University of Southern Denmark

• Associate Professor, Head of Inflammation Research PhD Jonas Heilskov Graversen