34. A High Throughput Mass Spectrometric Immunoassay for RANTES in Diabetic Populations: An Abundance of RANTES Microheterogeneity Identified
Poster: Mon 6:30-7:30PM
Paul E. Oran
Arizona State University
Paul E. Oran, Biodesign Institute, Arizona State University, Tempe, AZ 85287
Nisha D. Sherma, Biodesign Institute, Arizona State University, Tempe, AZ 85287
Jason W. Jarvis, Biodesign Institute, Arizona State University, Tempe, AZ 85287
Chad R. Borges, Biodesign Institute, Arizona State University, Tempe, AZ 85287
Randall W. Nelson, Biodesign Institute, Arizona State University, Tempe, AZ 85287
RANTES/CCL5 (aka Regulated on Activation, Normal T cell Expressed and Secreted) is CC chemokine that binds to CCR1, CCR3, CCR5, and DARC receptors and correspondingly has an integral role in inflammation, cell recruitment, and T cell activation. Notably, RANTES is also an antiviral agent that effectively restricts the entry of CCR5-tropic HIV-1 strains by means of the CCR5 receptor [1]. The clinical significance of RANTES is considerable as it has been associated with many diseases including kidney related complications (e.g. renal failure and renal cancer) and autoimmune diseases (e.g. arthritis, diabetes, and glomerulonephritis) [2]. As a result, much work has already been done regarding the characterization of RANTES microheterogeneity. The RANTES variants [3-68] and [4-68], products of two separate regulatory enzymes (Dipeptidyl Peptidase IV and Cathepsin G, respectively), have modified chemotactic and antiviral functionality compared to that of intact RANTES[1].

Here we present a high throughput mass spectrometric immunoassay (MSIA) for RANTES and related variants using MALDITOF-MS. The assay was applied to a population of 44 type 2 diabetics and 44 healthy controls. Along with the detection of [1-68], [3-68], and [4-68], an abundance of microheterogeneity was observed throughout both populations. These included: seven n- and/or c-terminally truncated variants, oxidized [1-68] and [3-68], glycated [1-68] and [3-68], and an unconfirmed o-linked glycosylated [1-68] variant. Relative percent abundance (RPA) values for these variants produced substantial differences between the diabetic population and healthy population (e.g. C-terminally truncated variants had average RPA values of 3 ± 1% and 8 ± 4% respectively, and [1-86] had average RPA values of 8 ± 3% and 35 ± 13%, respectively). Predictably, the glycated variant form (+162 Da) had significantly higher RPA values in the diabetic cohort. Further value from this assay may come in the form of it being an effective means in monitoring the in vivo enzymatic activity of DPP-IV and/or Cathepsin G. Future large scale population studies devoted towards more comprehensive screenings of RANTES variants may have important clinical utility in the understanding and diagnosis of many diseases.

1. Lim, J.K., et al., N-terminal proteolytic processing by cathepsin G converts RANTES/CCL5 and related analogs into a truncated 4-68 variant. J Leukoc Biol, 2006. 80(6): p. 1395-404.
2. Krensky, A.M. and Y.T. Ahn, Mechanisms of disease: regulation of RANTES (CCL5) in renal disease. Nat Clin Pract Nephrol, 2007. 3(3): p. 164-70.