Fernández et al. report on the safety and efficacy of implanting an intracortical microelectrode array in a blind person, suggesting the potential for this approach to restore functional vision. Image credit: Anita Ponne/Shutterstock.
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Dear Editor, We read with interest the article by Li and colleagues on the association between ACE inhibitors/angiotensin receptor blockers (ACE-I/ARB) use and in-hospital mortality among COVID-19 patients (1). The authors concluded that the use of ARB was associated with a significant reduction in in-hospital mortality among African American (AA) patients but not non-AA patients. However, we believe this conclusion is not per statistical principles and potentially misguiding readers. As noted by Altman and Bland (2), statistical analysis should be targeted to the clinical question: is the association between ARB use and in-hospital mortality different between AA and non-AA patients? To answer this question, one should directly compare the estimates (interaction test) (2), performed and reported by the authors. Here we argue that they did not accurately interpret this analysis. The authors showed an odds ratio (OR) of 0.196 (95% confidence interval [CI], 0.074 – 0.516) in the AA population and an OR of 0.687 (95% CI, 0.427 – 1.106) in the non-AA population. Accordingly, the interaction term was non-significant (95% CI, 0.185–1.292; P = 0.149). As the authors stated that “Statistical significance was defined as a 2-sided P value less than 0.05”, the correct interpretation of this result would be: the association of ACEi/ARB use and in-hospital mortality was not significantly different between these two populations (2). In contrast to this interpretation, the authors concluded that the association was only present in the AA population, which is not compatible with their analysis. The potential association between ACEi/ARB use and COVID-19 in-hospital mortality is of great interest to the medical community. Further, the ability to provide reliable subgroup analyses is vital in clinical decision-making (3). Interaction analyses are essential to answer the clinically relevant question of whether a specific subgroup of patients can benefit more from an intervention. However, we believe the correct interpretation of these results does not support the author’s conclusion.
Arthur M. Albuquerque, Carolina B. Santolia, Ashish Verma
Dear Editor, We appreciate Albuquerque, et al.’s interest in our paper [1,2], who raised the concern that we did not accurately interpret the interaction test, noting that “one should directly compare the estimates (interaction test)” and “the authors concluded that the association was only present in the AA population, which is not compatible with their analysis.” We would like to clarify that our primary clinical question is whether ACE-I/ARB use is associated with the COVID-19 outcomes in each sub-group. We used stratified analysis to answer the question because when race/ethnicity serves as a non-specific proxy for numerous (confounding) factors, these can be (partially) controlled for through stratification . Joint modeling of multiple groups is often used to gain power, but one needs to assume certain coherent distributions across different groups, which is not always true. Additionally, testing the interaction term is to assess association heterogeneity between groups, but it does not directly address whether the treatment is effective in each group. Specifically, we would like to elaborate on the following: 1) Our conclusion: “the use of ARB was associated with a significant reduction in in-hospital mortality among African American (AA) patients but not non-AA patients” was based on results from the stratified analysis. We reported that ARB in-hospital use was associated with reduced mortality in the AA stratum (OR=0.196; 95%CI:0.074-0.516; P=0.001) with statistical significance. On the other hand, the association in the non-AA stratum is not statistically significant (OR=0.687; 95%CI:0.427-1.106; P=0.122). As stated previously, our primary objective is to assess whether ACE-I/ARB use among AA patients is associated with COVID-19 mortality, rather than the difference between AA and non-AA patients. We were also aware that the estimated ORs across different stratum were not comparable as noted in [4-6]. 2) We performed the joint modeling of AA and non-AA patients as suggested by . Here, ARB in-hospital use was associated with reduced mortality in entire study population (OR=0.560; 95%CI:0.371-0.846; P=0.006). The interaction term added to the model was not significant (95%CI:0.185-1.292; P=0.149). Interpreting interaction terms in logistic regression is complex and a significant interaction term in log-odds may not be significant in difference-in-differences for probability. Furthermore, the assumption of the additive effects and imbalanced sample sizes could impact the inference. We believe these results and the interpretation are appropriate. We acknowledge that there are cases where comparing the interaction term in greater detail would be an important next step for understanding the association between COVID-19 mortality and race/ethnicity.
Shilong Li, Pei Wang, Li Li
Studies using the nonhuman primate model of M. tuberculosis /Simian Immunodeficiency Virus co-infection have revealed protective CD4+ T cell-independent immune responses that suppress LTBI reactivation. In particular, chronic immune activation rather than the mere depletion of CD4+ T cells correlates with reactivation due to SIV co-infection. Here, we administered cART at 2 weeks post-SIV co-infection to study if restoration of CD4+ T cell immunity occurred more broadly, and if this prevented reactivation of LTBI compared to cART initiated at 4 weeks post-SIV. Earlier initiation of cART enhanced survival, led to better control of viral replication and reduced immune activation in the periphery and lung vasculature thereby reducing the rate of SIV-induced reactivation. We observed robust CD8+ T effector memory responses and significantly reduced macrophage turnover in the lung tissue. However, skewed CD4+ T effector memory responses persisted and new TB lesions formed post SIV co-infection. Thus, reactivation of LTBI is governed by very early events of SIV infection. Timing of cART is critical in mitigating chronic immune activation. The novelty of these findings mainly relates to the development of a robust animal model of human Mtb/HIV co-infection that allows the testing of underlying mechanisms.
Riti Sharan, Shashank R. Ganatra, Allison N. Bucsan, Journey Cole, Dhiraj K. Singh, Xavier Alvarez, Maya Gough, Cynthia Alvarez, Alyssa Blakley, Justin Ferdin, Rajesh Thippeshappa, Bindu Singh, Ruby Escobedo, Vinay Shivanna, Edward J. Dick, Jr., Shannan Hall-Ursone, Shabaana A. Khader, Smriti Mehra, Jyothi Rengarajan, Deepak Kaushal
Mutations in Dyrk1b are associated with metabolic syndrome and non-alcoholic fatty liver disease in humans. Our investigations showed that DYRK1B levels are increased in the liver of patients with non-alcoholic liver steatohepatitis (NASH) and in mice fed with a high fat/sucrose diet. Increasing Dyrk1b levels in the mouse liver enhanced de novo lipogenesis (DNL), fatty-acid uptake, and TAG secretion and caused NASH and hyperlipidemia. Conversely, knockdown of Dyrk1b was protective against high-calorie induced hepatic steatosis and fibrosis and hyperlipidemia. Mechanistically, Dyrk1b increased DNL by activating mTORC2 in a kinase independent fashion. Accordingly, the Dyrk1b-induced NASH was fully rescued when mTORC2 was genetically disrupted. The elevated DNL was associated with increased plasma membrane sn-1,2-diacylglyerol levels and increased PKCε-mediated IRKT1150 phosphorylation, which resulted in impaired activation of hepatic insulin signaling and reduced hepatic glycogen storage. These findings provide new insights into the mechanisms that underlie Dyrk1b-induced hepatic lipogenesis and hepatic insulin resistance and identify Dyrk1b as a therapeutic target for NASH and insulin resistance in the liver.
Neha Bhat, Anand Narayanan, Mohsen Fathzadeh, Mario Kahn, Dongyan Zhang, Leigh Goedeke, Arpita Neogi, Rebecca L. Cardone, Richard G. Kibbey, Carlos Fernandez-Hernando, Henry N. Ginsberg, Dhanpat Jain, Gerald Shulman, Arya Mani
The dysregulation of energy homeostasis in obesity involves multi-hormone resistance. Although leptin and insulin resistance have been well characterized, catecholamine resistance remains largely unexplored. Murine β3-adrenergic receptor expression in adipocytes is orders of magnitude higher compared to other isoforms. While resistant to classical desensitization pathways, its mRNA (Adrb3) and protein expression are dramatically downregulated after ligand exposure (homologous desensitization). β3-adrenergic receptor downregulation also occurs after high fat diet feeding, concurrent with catecholamine resistance and elevated inflammation. This downregulation is recapitulated in vitro by TNFα treatment (heterologous desensitization). Both homologous and heterologous desensitization of Adrb3 were triggered by induction of the pseudokinase TRIB1 downstream of the EPAC/RAP2A/PI-PLC pathway. TRIB1 in turn degraded the primary transcriptional activator of Adrb3, CEBPα. EPAC/RAP inhibition enhanced catecholamine-stimulated lipolysis and energy expenditure in obese mice. Moreover, adipose tissue expression of genes in this pathway correlated with body weight extremes in a cohort of genetically diverse mice, and with BMI in two independent cohorts of humans. These data implicate a new signaling axis that may explain reduced hormone-stimulated lipolysis in obesity and resistance to therapeutic interventions with β3-adrenergic receptor agonists.
Joseph M. Valentine, Maryam Ahmadian, Omer Keinan, Mohammad Abu-Odeh, Peng Zhao, Xin Zhou, Mark P. Keller, Hui Gao, Ruth T. Yu, Christopher Liddle, Michael Downes, Jin Zhang, Aldons J. Lusis, Alan D. Attie, Ronald M. Evans, Mikael Rydén, Alan R. Saltiel
JCI This Month is a digest of the research, reviews, and other features published each month.
Animals, plants, and bacteria all display behavioral patterns that coincide with Earth’s light and dark cycles. These oscillating behaviors are the manifestation of the molecular circadian clock, a highly conserved network that maintains a near 24-hour rhythm even in the absence of light. In mammals, light signals are transmitted via the superchiasmatic nucleus (SCN) in the hypothalamus to synchronize peripheral clocks and coordinate physiological functions with the organism’s active period. This collection of reviews, curated by Amita Sehgal, considers the critical role of the circadian system in human health. Technology, work, and social obligations can disrupt optimal sleep and wake schedules, leaving humans vulnerable to diseases affecting the heart, brain, metabolism, and more. Sleep disorders as well as normal variations in human chronotype may exacerbate circadian disruptions, with profound consequences. These reviews emphasize that ongoing efforts to understand the complexities of human circadian rhythm will be essential for developing chronotherapies and other circadian-based interventions.