A Distinct Region in Erythropoietin that Induces Immuno/Inflammatory Modulation and Tissue Protection

Abstract

Beneficial effects of short-term whole-molecule erythropoietin (EPO) therapy have been demonstrated on several animal models of diverse central nervous system pathology. However, the increased hematocrit induced by EPOdriven marrow stimulation greatly limits its potential for side effect-free therapy. We created a library of EPO-derived fragments based on the hypothesis that 2 distinct functions, erythropoiesis and tissue protection, reside in different regions of the molecule. Several small EPO-derived peptides within the Aβ loop of whole EPO molecule were screened for tissue protection in EAE mice. The 19-mer JM-4 peptide that contains 2 cysteine molecules consistently demonstrated the most potent clinical beneficial effects without producing hematocrit alterations in animal models of EAE. The JM-4-induced tissue protection was associated with modulation of the immunoregulatory process that drives inflammation and provokes subsequent autoimmune damage. Like the whole EPO molecule, JM-4 effectively modulated immune/inflammatory reaction within both the peripheral lymphatic tissue and central nervous system. The major effects induced by JM-4 include blocked expansion of monocyte/dendritic antigen presenting cell and T helper 17 cell populations, decreased proinflammatory cytokine production, and sharply enhanced expansion of the regulatory T-cell population. JM-4 shows promise for treatment of a broad spectrum of neural and non-neural conditions associated with inflammation.

Parsing Physiological Functions of Erythropoietin One Domain at a Time

“…Apparently, length mattered considerably in this case: incorporation of the second cysteine was critical for these protective effects. Further understanding of the structure/function relationships stemming from this observation is likely to be interesting and will illuminate how EPO interacts with its receptor to attenuate inflammation.Yuan et al [7] were able to demonstrate the reversal of paralytic disease at the onset of symptoms without effects on RBC mass. Proinflammatory cytokine production was reduced.…”

“…Shorter linear peptides, and peptides without the cysteines, were far less effective. For example, a 17-mer peptide from the same region was far less effective [7].The diligence and persistence of Yuan et al [7] were worthwhile: they learned that while the 19-mer JM-4 was effective in 2 models of EAE, they also discovered that a shorter 17-mer containing only 1 cysteine residue was far less effective in these models. Apparently, length mattered considerably in this case: incorporation of the second cysteine was critical for these protective effects.…”

“…Fortunately, proteins are often divided into discrete domains with different functional activities residing in different regions of the molecule. In this issue of Neurotherapeutics, Yuan et al [7] discuss how they were able to dissociate a domain of EPO with antiinflammatory and neuroprotective effects from the regions of the molecule responsible for erythropoiesis. The ability to isolate the neuroprotective and anti-inflammatory effects of the molecule from its effects on red blood cell (RBC) development might enable the design of potent guardian molecules for unmet neurologic needs, without the potential side effect of EPO causing polycythemia, hypertension, and stroke.…”

“…Shorter linear peptides, and peptides without the cysteines, were far less effective. For example, a 17-mer peptide from the same region was far less effective [7].…”

“…Yuan et al [7] devised a successful strategy to parse the domains of EPO that might be free of its effect on RBC mass, while still retaining its neuroprotective effects. They made a library of peptides of lengths ranging from 7 to 25 amino acids, containing 1-2 cysteines.…”