Faculty Bibliography

INTRODUCTIONS:Excessive mechanical stress is closely associated with cell death in various conditions. Exposure of chondrocytes to excessive mechanical loading leads to a catabolic response as well as exaggerated cell death. Ferroptosis is a recently identified form of cell death during cell aging and degeneration. However, it's potential association with mechanical stress remains to be illustrated. OBJECTIVES:To identify whether excessive mechanical stress can cause ferroptosis. To explore the role of mechanical overloading in chondrocyte ferroptosis. METHODS:) mice OA model and chondrocytes cultured with high strain mechanical stress. Furthermore, the role of Piezo1 ion channel in chondrocyte ferroptosis and OA development was explored by using its inhibitor (GsMTx4) and agonist (Yoda1). Additionally, chondrocyte was cultured in calcium-free medium with mechanical stress, and ferroptosis phenotype was tested. RESULTS:Human cartilage and mouse chondrocyte experiments revealed that mechanical overloading can induce GPX4-associated ferroptosis. Conditional knockout of GPX4 in cartilage aggravated experimental OA process, while additional treatment with ferroptosis suppressor protein (FSP-1) and coenzyme Q10 (CoQ10) abated OA development in GPX4-CKO mice. In mouse OA model and chondrocyte experiments, inhibition of Piezo1 channel activity increased GPX4 expression, attenuated ferroptosis phenotype and reduced the severity of osteoarthritis. Additionally, high strain mechanical stress induced ferroptosis damage in chondrocyte was largely abolished by blocking calcium influx through calcium-free medium. CONCLUSIONS:Our findings show that mechanical overloading induces ferroptosis through Piezo1 activation and subsequent calcium influx in chondrocytes, which might provide a potential target for OA treatment.

OBJECTIVE:We explored the relationship between markers of infection and inflammation and mortality in patients with acute ischemic stroke who underwent thrombectomy. METHODS:We performed retrospective chart review of stroke patients who underwent thrombectomy at two tertiary academic centers between December 2018 and November 2020. Associations between discharge mortality, WBC count, neutrophil percentage, fever, culture data, and antibiotic treatment were analyzed using the Wilcoxon rank sum test, Student's t-test, and Fisher's exact test. Independent predictors of mortality were identified with multivariable analysis. Analyses were repeated excluding COVID-positive patients. RESULTS:Of 248 patients who underwent thrombectomy, 41 (17 %) died prior to discharge. Mortality was associated with admission WBC count (11 [8-14] vs. 9 [7-12], p = 0.0093), admission neutrophil percentage (78 % ± 11 vs. 71 % ± 14, p = 0.0003), peak WBC count (17 [13-22] vs. 12 [9-15], p < 0.0001), fever (71 % vs. 27 %, p < 0.0001), positive culture (44 % vs. 15 %, p < 0.0001), and days treated with antibiotics (3 [1-7] vs. 1 [0-4], p < 0.0001). After controlling for age, admission NIHSS and post-thrombectomy ASPECTS score, mortality was associated with admission WBC count (OR 13, CI 1.32-142, p = 0.027), neutrophil percentage (OR 1.03, CI 1.0-1.07, p = 0.045), peak WBC count (OR 301, CI 24-5008, p < 0.0001), fever (OR 24.2, CI 1.77-332, p < 0.0001), and positive cultures (OR 4.24, CI 1.87-9.62, p = 0.0006). After excluding COVID-positive patients (n = 14), peak WBC count, fever and positive culture remained independent predictors of mortality. CONCLUSION/CONCLUSIONS:Markers of infection and inflammation are associated with discharge mortality after thrombectomy. Further study is warranted to investigate the causal relationship of these markers with clinical outcome.

Epilepsy affects more than three million people in the United States. In approximately one-third of this population, anti-seizure medications do not control seizures. Many patients pursue surgical treatment that can include a procedure involving the implantation of electrodes for intracranial monitoring of seizure activity. For these cases, accurate mapping of the implanted electrodes on a patient's brain is crucial in planning the ultimate surgical treatment. Traditionally, electrode mapping results are presented in static figures that do not allow for dynamic interactions and visualizations. In collaboration with a clinical research team at a Level 4 Epilepsy Center, we developed N-Tools-Browser, a web-based software using WebGL and the X-Toolkit (XTK), to help clinicians interactively visualize the location and functional properties of implanted intracranial electrodes in 3D. Our software allows the user to visualize the seizure focus location accurately and simultaneously display functional characteristics (e.g., results from electrical stimulation mapping). Different visualization modes enable the analysis of multiple electrode groups or individual anatomical locations. We deployed a prototype of N-Tools-Browser for our collaborators at the New York University Grossman School of Medicine Comprehensive Epilepsy Center. Then, we evaluated its usefulness with domain experts on clinical cases.

There is an urgent need for an in-depth and systematic assessment of a wide range of predictive factors related to populations most at risk for delaying and refusing COVID-19 vaccination as cases of the disease surge across the United States. Many studies have assessed a limited number of general sociodemographic and health-related factors related to low vaccination rates. Machine learning methods were used to assess the association of 151 social and health-related risk factors derived from the American Community Survey 2019 and the Centers for Disease Control and Prevention (CDC) BRFSS with the response variables of vaccination rates and unvaccinated counts in 1,555 ZIP Codes in California. The performance of various analytical models was evaluated according to their ability to regress between predictive variables and vaccination levels. Machine learning modeling identified the Gradient Boosting Regressor (GBR) as the predictive model with a higher percentage of the explained variance than the variance identified through linear and generalized regression models. A set of 20 variables explained 72.90% of the variability of unvaccinated counts among ZIP Codes in California. ZIP Codes were shown to be a more meaningful geo-local unit of analysis than county-level assessments. Modeling vaccination rates was not as effective as modeling unvaccinated counts. The public health utility of this model provides for the analysis of state and local conditions related to COVID-19 vaccination use and future public health problems and pandemics.

A large portion of stroke disparities remains unexplained, even after adjusting for demographic, comorbidity, and health care access variables. There is a critical need to close this knowledge gap by investigating novel factors that may contribute to stroke disparities. Allostatic load (AL) is the lifetime adverse physiologic impact of needing to adjust to socially structured stressors such as racism. AL has been shown to increase health vulnerability and worsen outcomes in marginalized populations. We sought to assess the differential impact of AL on cognitive outcomes post intracerebral hemorrhage (ICH) across race-ethnicity. The Intracerebral Hemorrhage Outcomes Project (ICHOP) prospectively collected data from patients presenting to Columbia Medical Center with ICH from 3/2009 to 5/2016. Data included demographics, stroke scores, labs, complications, neuroimaging, medical history, and discharge data. Five markers of AL (HbA1c, WBC, SBP, HR, ALB) were obtained. An AL score was generated by summing the elements in each patient that fell outside normal ranges, with AL score ranging 0-5. A linear regression model, adjusted for stroke severity and ICH volumes, was used to evaluate the relationship between AL and Modified Telephone Interview for Cognitive Status (TICS-m) at discharge, stratified by race-ethnicity. Among 248 white, 195 black, and 261 Hispanic ICH patients, neither mean AL nor mean TICS differed by race/ethnicity (p = 0.51, p = 0.79 respectively). In the overall cohort AL did not predict TICS at discharge (Beta -1.0, SE 1.1, p = 0.353). In Whites (beta 1.18, SE 2.5, p = 0.646) and Hispanics (beta -0.95, SE 1.6, p = 0.552) AL was not associated with TICS at discharge. In Black patients, higher AL was associated with a decrease in TICS at discharge (beta -3.2, SE 1.5, p = 0.049). AL is an important determinant of post ICH outcomes for certain minority populations. AL may explain some of the unexplained health disparities in stroke populations.

OBJECTIVE/UNASSIGNED:Cognitive involvement in pediatric multiple sclerosis (MS) relative to adult MS is less defined. This study advances our understanding by measuring cognitive performances in pediatric MS, adult MS, and pediatric healthy controls. METHODS/UNASSIGNED:Consecutive relapsing pediatric MS participants from the United States Network of Pediatric MS Centers were compared with pediatric healthy controls and adults with relapsing MS. Participants were compared on two screening batteries: the Brief International Cognitive Assessment for MS and the Cogstate Brief Battery. Results were transformed to age-normative z scores. RESULTS/UNASSIGNED: < 0.001). CONCLUSION/UNASSIGNED:Pediatric MS patients do not differ from healthy pediatric controls on cognitive screens but perform better than adults with MS.

Loss of Paneth cells and their antimicrobial granules compromises the intestinal epithelial barrier and is associated with Crohn's disease, a major type of inflammatory bowel disease^1-7. Non-classical lymphoid cells, broadly referred to as intraepithelial lymphocytes (IELs), intercalate the intestinal epithelium^8,9. This anatomical position has implicated them as first-line defenders in resistance to infections, but their role in inflammatory disease pathogenesis requires clarification. The identification of mediators that coordinate crosstalk between specific IEL and epithelial subsets could provide insight into intestinal barrier mechanisms in health and disease. Here we show that the subset of IELs that express γ and δ T cell receptor subunits (γδ IELs) promotes the viability of Paneth cells deficient in the Crohn's disease susceptibility gene ATG16L1. Using an ex vivo lymphocyte-epithelium co-culture system, we identified apoptosis inhibitor 5 (API5) as a Paneth cell-protective factor secreted by γδ IELs. In the Atg16l1-mutant mouse model, viral infection induced a loss of Paneth cells and enhanced susceptibility to intestinal injury by inhibiting the secretion of API5 from γδ IELs. Therapeutic administration of recombinant API5 protected Paneth cells in vivo in mice and ex vivo in human organoids with the ATG16L1 risk allele. Thus, we identify API5 as a protective γδ IEL effector that masks genetic susceptibility to Paneth cell death.