Assessment of neuropeptide binding sites and the impact of biostable kinin and CAP2b analogue treatment on aphid (Myzus persicae and Macrosiphum rosae) stress tolerance.

BACKGROUND: Neuropeptides are regulators of critical life processes in insects and, due to their high specificity, represent potential targets in the development of greener insecticidal agents. Fundamental to this drive is understanding neuroendocrine pathways that control key physiological processes in pest insects and the screening of potential analogues. The current study investigated neuropeptide binding sites of kinin and CAPA (CAPA-1) in the aphids Myzus persicae and Macrosiphum rosae and the effect of biostable analogues on aphid fitness under conditions of desiccation, starvation and thermal (cold) stress. RESULTS: M. persicae and M. rosae displayed identical patterns of neuropeptide receptor mapping along the gut, with the gut musculature representing the main target for kinin and CAPA-1 action. While kinin receptor binding was observed in the brain and VNC of M. persicae, this was not observed in M. rosae. Furthermore, no CAPA-1 receptor binding was observed in the brain and VNC of either species. CAP2b/PK analogues (with CAPA receptor cross-activity) were most effective in reducing aphid fitness under conditions of desiccation and starvation stress, particularly analogues 1895 (2Abf-Suc-FGPRLa) and 2129 (2Abf-Suc-ATPRIa), which expedited aphid mortality. All analogues, with the exception of 2139-Ac, were efficient at reducing aphid survival under cold stress, although were equivalent in the strength of their effect. CONCLUSION: In demonstrating the effects of analogues belonging to the CAP2b neuropeptide family and key analogue structures that reduce aphid fitness under stress conditions, this research will feed into the development of second generation analogues and ultimately the development of neuropeptidomimetic-based insecticidal agents. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Plasma Kallikrein-Kinin System as a VEGF-Independent Mediator of Diabetic Macular Edema.

This study characterizes the kallikrein-kinin system in vitreous from individuals with diabetic macular edema (DME) and examines mechanisms contributing to retinal thickening and retinal vascular permeability (RVP). Plasma prekallikrein (PPK) and plasma kallikrein (PKal) were increased twofold and 11.0-fold (both P < 0.0001), respectively, in vitreous from subjects with DME compared with those with a macular hole (MH). While the vascular endothelial growth factor (VEGF) level was also increased in DME vitreous, PKal and VEGF concentrations do not correlate (r = 0.266, P = 0.112). Using mass spectrometry-based proteomics, we identified 167 vitreous proteins, including 30 that were increased in DME (fourfold or more, P < 0.001 vs. MH). The majority of proteins associated with DME displayed a higher correlation with PPK than with VEGF concentrations. DME vitreous containing relatively high levels of PKal and low VEGF induced RVP when injected into the vitreous of diabetic rats, a response blocked by bradykinin receptor antagonism but not by bevacizumab. Bradykinin-induced retinal thickening in mice was not affected by blockade of VEGF receptor 2. Diabetes-induced RVP was decreased by up to 78% (P < 0.001) in Klkb1 (PPK)-deficient mice compared with wild-type controls. B2- and B1 receptor-induced RVP in diabetic mice was blocked by endothelial nitric oxide synthase (NOS) and inducible NOS deficiency, respectively. These findings implicate the PKal pathway as a VEGF-independent mediator of DME.

Increased activity of coagulation factor XII (Hageman factor) causes hereditary angioedema type III.

Hereditary angioedema (HAE) is characterized clinically by recurrent acute skin swelling, abdominal pain, and potentially life-threatening laryngeal edema. Three forms of HAE have been described. The classic forms, HAE types I and II, occur as a consequence of mutations in the C1-inhibitor gene. In contrast to HAE types I and II, HAE type III has been observed exclusively in women, where it appears to be correlated with conditions of high estrogen levels--for example, pregnancy or the use of oral contraceptives. A recent report proposed two missense mutations (c.1032C-->A and c.1032C-->G) in F12, the gene encoding human coagulation factor XII (FXII, or Hageman factor) as a possible cause of HAE type III. Here, we report the occurrence of the c.1032C-->A (p.Thr328Lys) mutation in an HAE type III-affected family of French origin. Investigation of the F12 gene in a large German family did not reveal a coding mutation. Haplotype analysis with use of microsatellite markers is compatible with locus heterogeneity in HAE type III. To shed more light on the pathogenic relevance of the HAE type III-associated p.Thr328Lys mutation, we compared FXII activity and plasma levels in patients carrying the mutation with that of healthy control individuals. Our data strongly suggest that p.Thr328Lys is a gain-of-function mutation that markedly increases FXII amidolytic activity but that does not alter FXII plasma levels. We conclude that enhanced FXII enzymatic plasma activity in female mutation carriers leads to enhanced kinin production, which results in angioedema. Transcription of F12 is positively regulated by estrogens, which may explain why only women are affected with HAE type III. The results of our study represent an important step toward an understanding of the molecular processes involved in HAE type III and provide diagnostic and possibly new therapeutic opportunities.

Assessment of kininases in rheumatic diseases and the effect of therapeutic agents.

Bradykinin is degraded in human plasma by a carboxypeptidase to yield desArg9-bradykinin (DBK) which is then digested by angiotensin-converting enzyme (ACE) to the pentapeptide Arg-Pro-Pro-Gly-Phe and the tripeptide Ser-Pro-Phe. We have studied the rate of kinin degradation by each of these enzymes in patients with rheumatoid arthritis (RA) and with systemic lupus erythematosus (SLE), compared with the degradation rate in degenerative joint disease and normal subjects. Carboxypeptidase activity was the same in all individuals, but ACE activity was increased in the RA and SLE patients. We examined the effects of aspirin, sodium salicylate, auranofin, penicillamine, and corticosteroids on kinin metabolism, and all of these were marked inhibitors of ACE; however, only penicillamine had any demonstrable inhibition of carboxypeptidase. These observations suggest rapid degradation of DBK in patients with untreated RA and SLE, whereas drugs utilized in therapy have the opposite effects. Studies to examine the role of DBK in disease manifestations are in progress.