Anti-IL17A monoclonal antibody, clone 8B8

Refolding of human interleukin 17A (IL-17A) has been reported; however, the key refolding protocol was not robust enough to deliver consistent results and to be easily scaled up for crystallization. Here we report an optimized refolding method for IL-17A. Although co-crystal structures of IL-17A with ligands have been obtained with a high-affinity peptide and an anti-IL-17A Fab as stabilizers, neither the production yield nor the characterization of the IL-17A/Fab complex was reported. To facilitate co-crystallization of IL-17A with small-molecule compounds derived from our DNA encoded library, we also describe the method for yield enhancement of anti-IL-17A Fab production and characterize the IL-17A/Fab complex for the first time, providing an essential prerequisite for structure-based drug discovery targeting IL-17A. METHOD SUMMARY An Escherichia coli system was used for IL-17A expression. Two-way optimizations of the refolding conditions were implemented by exploring various ratios of oxidized and reduced forms of the oxido-shuffling reagents and the refolding duration. A detailed protocol for the optimized refolding has been submitted to protocols.io (doi 10.17504/protocols.io.bda3i2gn). Yield enhancement of anti-IL-17A Fab production was achieved after generating a stable HEK293-F cell line expressing the Fab fragment by G418 selection of transfected cells. The purified IL-17A/anti-IL-17A Fab complex was characterized by SDS-PAGE and western blotting. Single crystals of the quaternary complex, IL-17A/Fab/HAP (high affinity peptide) with small-molecule compounds derived from our DNA encoded library could be obtained using a batch method.

During mycobacterial infection, macroautophagy/autophagy, a process modulated by cytokines, is essential for mounting successful host responses. Autophagy collaborates with human immune responses against Mycobacterium tuberculosis (Mt) in association with specific IFNG secreted against the pathogen. However, IFNG alone is not sufficient to the complete bacterial eradication, and other cytokines might be required. Actually, induction of Th1 and Th17 immune responses are required for protection against Mt. Accordingly, we showed that IL17A and IFNG expression in lymphocytes from tuberculosis patients correlates with disease severity. Here we investigate the role of IFNG and IL17A during autophagy in monocytes infected with Mt H37Rv or the mutant Mt Delta RD1. Patients with active disease were classified as high responder (HR) or low responder (LR) according to their T cell responses against Mt. IL17A augmented autophagy in infected monocytes from HR patients through a mechanism that activated MAPK1/ERK2-MAPK3/ERK1 but, during infection of monocytes from LR patients, IL17A had no effect on the autophagic response. In contrast, addition of IFNG to infected monocytes, increased autophagy by activating MAPK14/p38 alpha both in HR and LR patients. Interestingly, proteins codified in the RD1 region did not interfere with IFNG and IL17A autophagy induction. Therefore, in severe tuberculosis patients' monocytes, IL17A was unable to augment autophagy because of a defect in the MAPK1/3 signaling pathway. In contrast, both IFNG and IL17A increased autophagy levels in patients with strong immunity to Mt, promoting mycobacterial killing. Our findings might contribute to recognize new targets for the development of novel therapeutic tools to fight the pathogen.