Expression and purification of non-N-glycosylated porcine interleukin 3 in yeast Pichia pastoris

Immunoglobulin light chains generate proinflammatory and profibrotic kidney injury

Because of the less-than-robust response to therapy and impact on choice of optimal chemotherapy and prognosis, chronic kidney disease has drawn attention in the treatment of multiple myeloma, a malignant hematologic disorder that can produce significant amounts of monoclonal immunoglobulin free light chains (FLCs). These low-molecular-weight proteins are relatively freely filtered through the glomerulus and are reabsorbed by the proximal tubule. The present study demonstrated that during the process of metabolism of immunoglobulin FLCs, ROS activated the STAT1 pathway in proximal tubule epithelium. STAT1 activation served as the seminal signaling molecule that produced the proinflammatory molecule IL-1β, as well as the profibrotic agent TGF-β by this portion of the nephron. These effects occurred in vivo and were produced specifically by the generation of hydrogen peroxide by the VL domain of the light chain. To the extent that the experiments reflect the human condition, these studies offer insights into the pathogenesis of progressive kidney failure in the setting of lymphoproliferative disorders, such as multiple myeloma, that feature increased circulating levels of monoclonal immunoglobulin fragments that require metabolism by the kidney.

Purification of Recombinant Glycoproteins from Pichia pastoris Culture Supernatants

Pichia pastoris is a common host organism for the production of recombinant proteins. While unglycosylated recombinant proteins derived from this yeast can be purified efficiently by only a few conventional chromatography steps, the purification of glycosylated recombinant proteins is a very challenging process due to the intrinsic feature of the yeast of hypermannosylation. The resulting vast glycosylation pattern on the recombinant target protein masks its physicochemical properties hampering a conventional downstream process. Here, we describe a fast and efficient two-step chromatography strategy, where both steps are operated in flow-through mode, to purify recombinant glycoproteins from P. pastoris culture supernatants.

Bioprocess development for extracellular production of recombinant human interleukin-3 (hIL-3) in Pichia pastoris

Human interleukin-3 (hIL-3) is a therapeutically important cytokine involved in the maturation and differentiation of various cells of the immune system. The codon-optimized hIL-3 gene was cloned in fusion with the N-terminus α-mating factor signal peptide of Saccharomyces cerevisiae under an inducible alcohol oxidase 1 (AOX1) and constitutive glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter. A Zeocin concentration up to 2000 mg/L was used to select hyper-producers. The shake flask cultivation studies in the Pichia pastoris GS115 host resulted a maximum recombinant hIL-3 expression level of 145 mg/L in the extracellular medium under the control of AOX1 promoter. The batch fermentation strategy allowed us to attain a fairly pure glycosylated hIL-3 protein in the culture supernatant at a final concentration of 475 mg/L with a high volumetric productivity of 4.39 mg/L/h. The volumetric product concentration achieved at bioreactor level was 3.28 folds greater than the shake flask results. The 6x His-tagged protein was purified using Ni–NTA affinity chromatography and confirmed further by western blot analysis using anti-6x His tag antibody. The glycosylation of recombinant hIL-3 protein was confirmed in a PNGase F deglycosylation reaction where it showed a molecular weight band pattern similar to E. coli produced non-glycosylated hIL-3 protein. The structural properties of recombinant hIL-3 protein were confirmed by CD and fluorescence spectroscopy where protein showed 40 % α-helix, 12 % β-sheets with an emission maxima at 343 nm. MALDI-TOF-TOF analysis was used to establish the protein identity. The biological activity of purified protein was confirmed by the human erythroleukemia TF-1 cell proliferation assay.