CAP37, a protein constitutively expressed in human neutrophils and induced in response to infection in corneal epithelial cells, plays a significant role in host defense against infection. Initially identified through its potent bactericidal activity for Gram-negative bacteria, it is now known that CAP37 regulates numerous host cell functions, including corneal epithelial cell chemotaxis. Our long-term goal is to delineate the domains of CAP37 that define these functions and synthesize bioactive peptides for therapeutic use. We report the novel finding of a multifunctional domain between aa 120 and 146. Peptide analogs 120-146 QR, 120-146 QH, 120-146 WR, and 120-146 WH were synthesized and screened for induction of corneal epithelial cell migration by use of the modified Boyden chamber assay, antibacterial activity, and LPS-binding activity. In vivo activity was demonstrated by use of mouse models of sterile and infected corneal wounds. The identity of the amino acid at position 132 (H vs. R) was important for cell migration and in vivo corneal wound healing. All analogs demonstrated antimicrobial activity. However, analogs containing a W at position 131 showed significantly greater antibacterial activity against the Gram-negative pathogen Pseudomonas aeruginosa. All analogs bound P. aeruginosa LPS. Topical administration of analog 120-146 WH, in addition to accelerating corneal wound healing, effectively cleared a corneal infection as a result of P. aeruginosa. In conclusion, we have identified a multifunctional bioactive peptide, based on CAP37, that induces cell migration, possesses antibacterial and LPS-binding activity, and is effective at healing infected and noninfected corneal wounds in vivo.

No abstract

IntroductionSevere acute kidney injury (AKI) and chronic kidney disease (CKD) are considered to be uncommon in patients with acquired thrombotic thrombocytopenic purpura. However, a recent case series from a tertiary care hospital indicated that 54 (59%) of 92 patients with thrombotic thrombocytopenic purpura presented with AKI; 14 (15%) required dialysis; and 12 (22%) of the 54 patients had CKD at follow-up.MethodsIn this prospective analysis of 78 patients diagnosed with their first episode of thrombotic thrombocytopenic purpura and enrolled in the Oklahoma Thrombotic Thrombocytopenic Purpura Registry from 1995 to 2015, we assessed AKI at diagnosis using Kidney Disease: Improving Global Outcomes criteria, and CKD at follow-up as defined by estimated glomerular filtration rate <60 ml/min per 1.73 m2 determined by the Chronic Kidney Disease-Epidemiology Collaboration equation.ResultsForty-five (58%) patients had AKI; 8 (10%) had stage 3 AKI, and 3 (4%) required dialysis. AKI was not associated with the patients’ demographic or presenting clinical features. Three of the 8 patients with stage 3 AKI died; among the 5 survivors, estimated glomerular filtration rate was 77 to 107 ml/min per 1.73 m2 (median, 92) with median follow-up of 8.1 years. Among all 62 surviving patients who have had follow-up serum creatinine measurements, 4 (6%) had CKD with median follow-up of 6.4 years. AKI was not associated with the occurrence of CKD (P = 0.74). No patients have required continuing renal replacement therapy.DiscussionIn this population-based prospective cohort of consecutive patients with thrombotic thrombocytopenic purpura, without selection or referral bias, severe AKI and CKD are uncommon.

Dexras1 is a small GTPase and plays a central role in neuronal iron trafficking. We have shown that stimulation of glutamate receptors activates neuronal nitric oxide synthase, leading to S-nitrosylation of Dexras1 and a physiological increase in iron uptake. Here we report that Dexras1 is phosphorylated by PKA on serine 253, leading to a suppression of iron influx. These effects were directly associated with the levels of S-nitrosylated Dexras1, whereby PKA activation reduced Dexras1 S-nitrosylation in a dose dependent manner. Moreover, we found that adiponectin modulates Dexras1 via PKA. Hence these findings suggest the involvement of the PKA pathway in modulating glutamate-mediated ROS in neurons, and hint to a functional crosstalk between S-nitrosylation and phosphorylation.