Inflammatory cytokines like TNF play a central role in autoimmune disorders such as rheumatoid arthritis. We identified the tyrosine kinase bone marrow kinase on chromosome X (BMX) as an essential component of a shared inflammatory signaling pathway. Transient depletion of BMX strongly reduced secretion of IL-8 in cell lines and primary human cells stimulated by TNF, IL-1β, or TLR agonists. BMX was required for phosphorylation of p38 MAPK and JNK, as well as activation of NF-κB. The following epistasis analysis indicated that BMX acts downstream of or at the same level as the complex TGF-β activated kinase 1 (TAK1)–TAK1 binding protein. At the cellular level, regulation of the IL-8 promoter required the pleckstrin homology domain of BMX, which could be replaced by an ectopic myristylation signal, indicating a requirement for BMX membrane association. In addition, activation of the IL-8 promoter by in vitro BMX overexpression required its catalytic activity. Genetic ablation of BMX conferred protection in the mouse arthritis model of passive K/BxN serum transfer, confirming that BMX is an essential mediator of inflammation in vivo. However, genetic replacement with a catalytically inactive BMX allele was not protective in the same arthritis animal model. We conclude that BMX is an essential component of inflammatory cytokine signaling and that catalytic, as well as noncatalytic functions of BMX are involved.
Objective
PF-06438179/GP1111 (PF-SZ-IFX) is an infliximab biosimilar. We evaluated the extended in-use physicochemical and biological stability of PF-SZ-IFX upon preparation for intravenous infusion.
Methods
Two batches of PF-SZ-IFX were reconstituted to a concentration of 10 mg/mL and subsequently diluted to 0.4 and 4.0 mg/mL, representing the clinically relevant range for intravenous infusion. Dilution was performed in polyethylene saline infusion bags, which are commonly used in clinical practice. To simulate product handling under worst-case conditions, reconstituted solutions were stored for up to 30 days at 5 ± 3 °C and up to 14 days at 25 ± 2 °C (60 ± 5% relative humidity); diluted solutions were stored for up to 30 days under the same sets of conditions. Physicochemical and biological stability were evaluated according to pH, osmolality, appearance, particulate content, protein concentration, proportions of molecular weight variants and charge variants and potency. Standard and state-of-the-art analytical techniques were employed, including imaged isoelectric focusing, size exclusion chromatography, reducing sodium dodecyl sulphate capillary electrophoresis and functional cell-based bioassay.
Results
Across batches and concentrations of PF-SZ-IFX, all parameters resided within the predefined acceptance criteria, including pH, osmolality, particulate content, clarity, protein concentration, molecular weight variants, charge variants and potency, for up to 30 days under both storage conditions tested (up to 14 days for reconstituted samples stored at 25 ± 2 °C).
Conclusions
Physicochemical and biological analyses demonstrated that the infliximab biosimilar PF-SZ-IFX was not affected by extended storage of the diluted preparations used for intravenous infusion.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.