No abstract

Background Asparaginase is a critical component of lymphoblastic leukemia therapy, with intravenous pegaspargase (PEG) as the current standard product. Acute adverse events (aAEs) during PEG infusion are difficult to interpret, representing a mix of drug‐inactivating hypersensitivity and noninactivating reactions. Asparaginase Erwinia chrysanthemi (ERW) is approved for PEG hypersensitivity, but is less convenient, more expensive, and yields lower serum asparaginase activity (SAA). We began a policy of universal premedication and SAA testing for PEG, hypothesizing this would reduce aAEs and unnecessary drug substitutions. Procedure Retrospective chart review of patients receiving asparaginase before and after universal premedication before PEG was conducted, with SAA performed 1 week later. We excluded patients who had nonallergic asparaginase AEs. Primary end point was substitution to ERW. Secondary end points included aAEs, SAA testing, and cost. Results We substituted to ERW in 21 of 122 (17.2%) patients pre‐policy, and 5 of 68 (7.4%) post‐policy (RR, 0.427; 95% CI, 0.27–0.69, P = 0.028). All completed doses of PEG yielded excellent SAA (mean, 0.90 units/mL), compared with ERW (mean, 0.15 units/mL). PEG inactivation post‐policy was seen in 2 of 68 (2.9%), one silent and one with breakthrough aAE. The rate of aAEs pre/post‐policy was 17.2% versus 5.9% (RR, 0.342; 95% CI, 0.20–0.58, P = 0.017). Grade 4 aAE rate pre/post‐policy was 15% versus 0%. Cost analysis predicts $125 779 drug savings alone per substitution prevented ($12 402/premedicated patient). Conclusions Universal premedication reduced substitutions to ERW and aAE rate. SAA testing demonstrated low rates of silent inactivation, and higher SAA for PEG. A substantial savings was achieved. We propose universal premedication for PEG be standard of care.

The lens has been considered to be an immune privileged site not susceptible to the immune processes normally associated with tissue injury and wound repair. However, as greater insight into the immune surveillance process is gained, we have reevaluated the concept of immune privilege. Our studies using an N-cadherin lens-specific conditional knockout mouse, N-cadΔlens, show that loss of this cell-cell junctional protein leads to lens degeneration, necrosis and fibrotic change, postnatally. The degeneration of this tissue induces an immune response resulting in immune cells populating the lens that contribute to the development of fibrosis. Additionally, we demonstrate that the lens is connected to the lymphatic system, with LYVE(+) labeling reaching the lens along the suspensory ligaments that connect the lens to the ciliary body, providing a potential mechanism for the immune circulation. Importantly, we observe that degeneration of the lens activates an immune response throughout the eye, including cornea, vitreous humor, and retina, suggesting a coordinated protective response in the visual system to defects of a component tissue. These studies demonstrate that lens degeneration induces an immune response that can contribute to the fibrosis that often accompanies lens dysgenesis, a consideration for understanding organ system response to injury.

The lens and central cornea are avascular. It was assumed that the adult lens had no source of immune cells and that the basement membrane capsule surrounding the lens was a barrier to immune cell migration. Yet, microfibril‐associated protein‐1 (MAGP1)‐rich ciliary zonules that originate from the vasculature‐rich ciliary body and extend along the surface of the lens capsule, form a potential conduit for immune cells to the lens. In response to cornea debridement wounding, we find increased expression of MAGP1 throughout the central corneal stroma. The immune cells that populate this typically avascular region after wounding closely associate with this MAGP1‐rich matrix. These results suggest that MAGP1‐rich microfibrils support immune cell migration post‐injury. Using this cornea wound model, we investigated whether there is an immune response to the lens following cornea injury involving the lens‐associated MAGP1‐rich ciliary zonules. Our results provide the first evidence that following corneal wounding immune cells are activated to travel along zonule fibers that extend anteriorly along the equatorial surface of the lens, from where they migrate across the anterior lens capsule. These results demonstrate that lens‐associated ciliary zonules are directly involved in the lens immune response and suggest the ciliary body as a source of immune cells to the avascular lens.

Tissue development and regeneration involve high-ordered morphogenetic processes that are governed by elements of the cytoskeleton in conjunction with cell adhesion molecules. Such processes are particularly important in the lens whose structure dictates its function. Studies of our lens-specific N-cadherin conditional knockout mouse (N-cadcKO) revealed an essential role for N-cadherin in the migration of the apical tips of differentiating lens fiber cells along the apical surfaces of the epithelium, a region termed the Epithelial Fiber Interface (EFI), that is necessary for normal fiber cell elongation and the morphogenesis. Studies of the N-cadcKO lens suggest that N-cadherin function in fiber cell morphogenesis is linked to the activation of Rac1 and myosin II, both signaling pathways central to the regulation of cell motility including determining the directionality of cellular movement. The absence of N-cadherin did not disrupt lateral contacts between fiber cells during development, and the maintenance of Aquaporin-0 and increased expression of EphA2 at cell-cell interfaces suggests that these molecules may function in this role. E-cadherin was maintained in newly differentiating fiber cells without interfering with expression of lens-specific differentiation proteins but was not able to replace N-cadherin function in these cells. The dependence of migration of the fiber cell apical domains along the EFI for lens morphogenesis on N-cadherin provides new insight into the process of tissue development.

Proper remodeling of the endocardial cushions into thin fibrous valves is essential for gestational progression and long-term function. This process involves dynamic interactions between resident cells and their local environment, much of which is not understood. In this study, we show that deficiency of the cell-cell adhesion protein cadherin-11 (cad-11) results in significant embryonic and perinatal lethality primarily due to valve related cardiac dysfunction. While endocardial to mesenchymal transformation is not abrogated, mesenchymal cells do not homogeneously cellularize the cushions. These cushions remain thickened with disorganized ECM, resulting in pronounced aortic valve insufficiency. Mice that survive to adulthood maintain thickened and stenotic semilunar valves, but interestingly do not develop calcification. Cad-11 −/− aortic valve leaflets contained reduced sox9 activity, β1 integrin expression, and RhoA-GTP activity, suggesting that remodeling defects are due to improper migration and/or cellular contraction. Cad-11 deletion or siRNA knockdown reduced migration, eliminated collective migration, and impaired 3D matrix compaction by aortic valve interstitial cells (VIC). Cad-11 depleted cells in culture contained few filopodia, stress fibers, or contact inhibited locomotion. Transfection of Cad-11 depleted cells with constitutively active RhoA restored cell phenotypes. Together, these results identify cadherin-11 mediated adhesive signaling for proper remodeling of the embryonic semilunar valves.

Objective Calcific aortic valve disease is a significant clinical problem for which the regulatory mechanisms are poorly understood. Enhanced cell-cell adhesion is a common mechanism of cellular aggregation, but its role in calcific lesion formation is not known. Cadherin-11 (Cad-11) has been associated with lesion formation in vitro, but its function during adult valve homeostasis and pathogenesis is not known. This study aims to elucidate the specific functions of Cad-11 and its downstream targets RhoA and Sox9 in extracellular matrix remodeling and aortic valve calcification. Approach and Results We conditionally overexpressed Cad-11 in murine heart valves using a novel double transgenic Nfatc1Cre;R26-Cad11Tg/Tg mouse model. These mice developed hemodynamically significant aortic stenosis with prominent calcific lesions in the aortic valve leaflets. Cad-11 overexpression upregulated downstream targets RhoA and Sox9 in the valve interstitial cells, causing calcification and extensive pathogenic extracellular matrix remodeling. Aortic valve interstitial cells overexpressing Cad-11 in an osteogenic environment in vitro rapidly form calcific nodules analogous to in vivo lesions. Molecular analyses revealed upregulation of osteoblastic and myofibroblastic markers. Treatment with a ROCK inhibitor attenuated nodule formation, further supporting that Cad-11 driven calcification acts through the small GTPase RhoA/ROCK signaling pathway. Conclusions This study identifies one of the underlying molecular mechanisms of heart valve calcification and demonstrates that overexpression of Cad-11 upregulates RhoA and Sox9 to induce calcification and extracellular matrix remodeling in adult aortic valve pathogenesis. The findings provide a potential molecular target for clinical treatment.

Women with Marfan syndrome (MFS) are at high risk for pregnancy-associated aortic dissection. Pathogenic models that singularly invoke hemodynamic stress are difficult to reconcile with predominant postnatal occurrence of aortic tear, often occurring weeks to months after delivery. In consideration of events that peak at term, are sustained after delivery, and might synergize with previously defined signaling pathways implicated in aneurysm progression, we examined the hormone oxytocin, which initiates uterine contraction and milk letdown for the duration of lactation through phosphorylation of extracellular signal–regulated kinase (ERK). In a mouse model of MFS that shows highly penetrant postnatal aortic dissection, risk was strongly attenuated by preventing lactation or use of an oxytocin receptor antagonist. Survival correlated inversely with the extent of ERK activation in the aortic wall, and strong protection was observed upon attenuation of ERK phosphorylation using an inhibitor of ERK kinase (MEK) or the U.S. Food and Drug Administration–approved medication hydralazine, offering potential therapeutic strategies for pregnancy-associated vascular catastrophe in the setting of MFS.