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Biology subjects

Harris, I.

Publications and source records attributed to Harris, I..

5 recordsLinked to original sources

Programmable Lipid Nanoparticle Targeting via Corona Engineering

Lipid nanoparticles (LNPs) are a versatile platform for in vivo delivery of biomolecules, yet systemically administered LNPs predominantly accumulate in the liver, limiting extrahepatic applications. This tropism arises from LNP adsorption of serum proteins, particularly apolipoprotein E (ApoE), which binds to LDL receptors (LDLR) on hepatocytes. Here, we overcome this tropism with two compatible strategies. First, we engineer dead ApoE mutants (dApoE) with five receptor-binding domain substitutions that selectively disrupt the ApoE-LDLR interaction but retain lipid binding. In cultured cells, pre-coating with these dApoE markedly inhibited LDLR-mediated uptake. Second, we pretreat cells with hyperactive PCSK9 (haPCSK9) to internalize surface LDLR, similarly reducing the LDLR-mediate uptake of LNPs. In vivo, both strategies substantially reduced liver LNP transduction without inducing redistribution to other major organs. To retarget LNP to new cell types we combined antibody conjugation with dApoE or haPCSK9, effectively engineering tropism to T cells, brain and lung tissues in vivo with substantially reduced hepatic background. In pilot studies, this strategy enabled specific delivery of reporter mRNAs to additional tissues, including megakaryocytes, hematopoietic progenitor cells, and cardiac tissue, and in aged T cells, to deliver miRNA cargos that produced a sustained reduction in DNA damage markers following a single systemic dose. dApoE coated CD5-targeted LNPs generated CAR+ T cells that retained cytotoxicity against CD19+ targets, while simultaneously reducing hepatocyte transduction by 90%. These findings establish a modular framework that integrates dApoE and haPCSK9-mediated detargeting with antibody-based retargeting, allowing for improvements in LNP specificity and broadening the therapeutic scope of LNPs.

bioengineering↗

Evolutionary trade-offs between intergenerational and transgenerational fitness effects

Intergenerational and transgenerational fitness effects can shape evolutionary processes. Theoretically, however, intergenerational and transgenerational effects can trade-off with each other with profound consequences for evolutionary processes. Here we show that beneficial intergenerational effects that increase offspring fitness can result in detrimental transgenerational effects that decrease great-grand offspring fitness. We combined theoretical modelling and experimental approaches to investigate multigenerational fitness trade-offs induced by larval starvation in Caenorhabditis elegans. We demonstrate that larval starvation triggers a cascading effect: starved individuals suffered marked fitness losses, their direct offspring enjoyed fitness gains in both starvation and ad libitum environments, but great-grand-offspring paid fitness costs. Demographic simulation models revealed that genotypes exploiting this short-term intergenerational advantage outcompete rival genotypes despite the deferred transgenerational debt. Our findings demonstrate that adaptive intergenerational gains can be intrinsically linked to maladaptive transgenerational outcomes, challenging the assumption that transgenerational effects are inherently beneficial and highlighting the role of multigenerational trade-offs in evolution.

evolutionary biology↗

Embodied processing in whisker somatosensory cortex during exploratory behaviour in freely moving mice

Sensory systems have evolved to solve computational challenges that animals face during behaviour in their natural environments. To illuminate how sensory cortex operates under such conditions, we investigated the function of neurons in whisker-related Somatosensory Cortex (wS1) of freely moving mice, engaged in tactile exploratory behaviour. By recording neural activity from wS1 whilst tracking the mouse body in 3D, we found that wS1 neurons are substantially modulated by body state (configuration of individual body-parts and their derivatives), even in the absence of whisker afferent input. Most neurons were modulated by multiple dimensions of body state, with the most prominently encoded being the angle of the head to the body and locomotion speed. Overall, our data suggest that sensory cortex functions as an embodied representation, which integrates signals from its associated sense organ within a body schema.

neuroscience↗

Impact of Fkbp5 x Early Life Adversity x Sex in Humanized Mice on Multidimensional Stress Responses and Circadian Rhythmicity

The cumulative load of genetic predisposition, early life adversity (ELA) and lifestyle shapes the prevalence of psychiatric disorders. Single nucleotide polymorphisms (SNPs) in the human FKBP5 gene were shown to modulate disease risk. To enable investigation of disease-related SNPs in behaviorally relevant context, we generated humanized mouse lines carrying either the risk (AT) or the resiliency (CG) allele of the rs1360780 locus and exposed litters of these mice to maternal separation. Behavioral and physiological aspects of their adult stress responsiveness displayed interactions of genotype, early life condition and sex. In humanized females carrying the CG-but not the AT-allele, ELA led to altered HPA-axis functioning, exploratory behavior and sociability. These changes correlated with differential expression of genes in the hypothalamus, where synaptic transmission, metabolism, and circadian entrainment pathways were deregulated. Our data suggest an integrative role of FKBP5 in shaping the sex-specific outcome of ELA in adulthood.

neuroscience↗

Peripartum cardiomyopathy and hypertensive disorders of pregnancy and cardiovascular events among 1.6 million California pregnancies

BackgroundCardiovascular complications during and soon after pregnancy present an opportunity to assess risk for subsequent cardiovascular disease. We sought to determine whether peripartum cardiomyopathy and hypertensive disorder of pregnancy subtypes predict future myocardial infarction, heart failure, or stroke independent of one another and independent of other risks like gestational diabetes, preterm birth, and intrauterine growth restriction.\n\nMethods and ResultsThe California Healthcare Cost and Utilization Project database was used to identify all hospitalized pregnancies from 2005-2009, with follow-up through 2011, for a retrospective cohort study. Pregnancies, exposures, covariates and outcomes were defined by ICD-9 codes. Among 1.6 million pregnancies (mean age 28y; median follow-up time to event 2.7y), 558 cases of peripartum cardiomyopathy, 123,603 cases of hypertensive disorders of pregnancy, 107,636 cases of gestational diabetes, 116,768 preterm births, and 23,504 cases of intrauterine growth restriction were observed. Using multivariable Cox proportional hazards models, peripartum cardiomyopathy was independently associated with a 13.0-fold increase in myocardial infarction [95%CI, 4.1-40.9], a 39.2-fold increase in heart failure [95%CI, 30.0-51.9], and a 7.7-fold increase in stroke [95%CI, 2.4-24.0]. Hypertensive disorders of pregnancy were associated with a 1.4 [95%CI, 1.0-2.0] to 7.6 [95%CI, 5.4-10.7] fold higher risk of myocardial infarction, heart failure, and stroke. Gestational diabetes, preterm birth, and intrauterine growth restriction had more modest associations with CVD.\n\nConclusionsThese findings support close monitoring of women with cardiovascular pregnancy complications for prevention of early subsequent cardiovascular events and further study of mechanisms underlying their development.

epidemiology↗