Road Less Traveled: Drug Hypersensitivity to Fluoroquinolones, Vancomycin, Tetracyclines, and Macrolides.

While fluoroquinolones, vancomycin, macrolides, and tetracyclines are generally safe antibiotics, they can induce both immediate and delayed hypersensitivity reactions (HSRs). Historically, less has been published on allergies to these antibiotics compared to beta lactams, but the prevalence of non-beta lactam HSRs is increasing. To fluoroquinolones, immediate HSRs are more common than delayed reactions. Both IgE and non-IgE mechanisms, such as the mast cell receptor Mas-related G protein-coupled receptor X2 (MRGPRX2), have been implicated in fluoroquinolone-induced anaphylaxis. Skin testing for fluoroquinolones is controversial, and the gold standard for diagnosis is a graded dose challenge. To vancomycin, the most common reaction is vancomycin infusion reaction (previously called "red man syndrome"), which is caused by infusion rate-dependent direct mast cell degranulation. Severity can range from flushing and pruritis to angioedema, bronchospasm, and hypotension that mimic type I HSRs. MRGPRX2 has been implicated in vancomycin infusion reactions. IgE-mediated HSRs to vancomycin are rare. Vancomycin skin testing yields high false positive rates. Thus, direct provocation challenge with slower infusion rate and/or antihistamine pre-treatment is preferred if symptoms are mild to moderate, and desensitization can be considered if symptoms are severe. To tetracyclines, non-IgE-mediated and delayed HSRs predominate with cutaneous reactions being the most common. There is no standardized skin testing for tetracyclines, and avoidance is generally recommended after a severe reaction because of the paucity of data for testing. Graded dose challenges and desensitizations can be considered for alternative or index tetracyclines if there are no alternatives. With macrolides, urticaria/angioedema is the most common immediate HSR, and rash is the most common delayed HSR. The predictive value for skin testing to macrolides is similarly poorly defined. In general, HSRs to fluroquinolones, vancomycin, macrolides, and tetracyclines are challenging to diagnose given the lack of validated skin testing and in vitro testing. Direct provocation challenge remains the gold standard for diagnosis, but the benefits of confirming an allergy may not outweigh the risk of a severe reaction. Skin testing, direct provocation challenge, and/or desensitization to the index non-beta lactam antibiotic or alternatives in its class may be reasonable approaches depending on the clinical context and patient preferences.

Endothelial CaMKII as a regulator of eNOS activity and NO-mediated vasoreactivity.

The multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a serine/threonine kinase important in transducing intracellular Ca2+ signals. While in vitro data regarding the role of CaMKII in the regulation of endothelial nitric oxide synthase (eNOS) are contradictory, its role in endothelial function in vivo remains unknown. Using two novel transgenic models to express CaMKII inhibitor peptides selectively in endothelium, we examined the effect of CaMKII on eNOS activation, NO production, vasomotor tone and blood pressure. Under baseline conditions, CaMKII activation was low in the aortic wall. Consistently, systolic and diastolic blood pressure, heart rate and plasma NO levels were unaltered by endothelial CaMKII inhibition. Moreover, endothelial CaMKII inhibition had no significant effect on NO-dependent vasodilation. These results were confirmed in studies of aortic rings transduced with adenovirus expressing a CaMKII inhibitor peptide. In cultured endothelial cells, bradykinin treatment produced the anticipated rapid influx of Ca2+ and transient CaMKII and eNOS activation, whereas CaMKII inhibition blocked eNOS phosphorylation on Ser-1179 and dephosphorylation at Thr-497. Ca2+/CaM binding to eNOS and resultant NO production in vitro were decreased under CaMKII inhibition. Our results demonstrate that CaMKII plays an important role in transient bradykinin-driven eNOS activation in vitro, but does not regulate NO production, vasorelaxation or blood pressure in vivo under baseline conditions.

Deletion of Methionine Sulfoxide Reductase A Does Not Affect Atherothrombosis but Promotes Neointimal Hyperplasia and Extracellular Signal-Regulated Kinase 1/2 Signaling.

OBJECTIVE: Emerging evidence suggests that methionine oxidation can directly affect protein function and may be linked to cardiovascular disease. The objective of this study was to define the role of the methionine sulfoxide reductase A (MsrA) in models of vascular disease and identify its signaling pathways. APPROACH AND RESULTS: MsrA was readily identified in all layers of the vascular wall in human and murine arteries. Deletion of the MsrA gene did not affect atherosclerotic lesion area in apolipoprotein E-deficient mice and had no significant effect on susceptibility to experimental thrombosis after photochemical injury. In contrast, the neointimal area after vascular injury caused by complete ligation of the common carotid artery was significantly greater in MsrA-deficient than in control mice. In aortic vascular smooth muscle cells lacking MsrA, cell proliferation was significantly increased because of accelerated G1/S transition. In parallel, cyclin D1 protein and cdk4/cyclin D1 complex formation and activity were increased in MsrA-deficient vascular smooth muscle cell, leading to enhanced retinoblastoma protein phosphorylation and transcription of E2F. Finally, MsrA-deficient vascular smooth muscle cell exhibited greater activation of extracellular signal-regulated kinase 1/2 that was caused by increased activity of the Ras/Raf/mitogen-activated protein kinase signaling pathway. CONCLUSIONS: Our findings implicate MsrA as a negative regulator of vascular smooth muscle cell proliferation and neointimal hyperplasia after vascular injury through control of the Ras/Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase 1/2 signaling pathway.

Oxidative activation of the Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) regulates vascular smooth muscle migration and apoptosis.

Activation of the Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and reactive oxygen species (ROS) promote neointimal hyperplasia after vascular injury. CaMKII can be directly activated by ROS through oxidation. In this study, we determined whether abolishing the oxidative activation site of CaMKII alters vascular smooth muscle cell (VCMC) proliferation, migration and apoptosis in vitro and neointimal formation in vivo. VSMC isolated from a knock-in mouse with oxidation-resistant CaMKIIδ (CaMKII M2V) displayed similar proliferation but decreased migration and apoptosis. Surprisingly, ROS production and expression of the NADPH oxidase subunits p47 and p22 were decreased in M2V VSMC, whereas superoxide dismutase 2 protein expression was upregulated. In vivo, after carotid artery ligation, no differences in neointimal size or remodeling were observed. In contrast to VSMC, CaMKII expression and autonomous activity were significantly higher in M2V compared to WT carotid arteries, suggesting that an autoregulatory mechanism determines CaMKII activity in vivo. Our findings demonstrate that preventing oxidative activation of CaMKII decreases migration and apoptosis in vitro and suggest that CaMKII regulates ROS production. Our study presents novel evidence that CaMKII expression in vivo is regulated by a negative feedback loop following oxidative activation.