Biology subjects

McGrath, S.

Publications and source records attributed to McGrath, S..

9 recordsLinked to original sources

bioRxiv2025

A common Iba1 antibody labels vasopressin neurons in mice

There are a wide variety of commercially available antibodies for labeling microglial cells based on different protein targets, as well as antibodies for the same protein target made in different species. While this array of targets and hosts allows for flexibility in immunohistochemical experiments, it is important to validate that different antibodies provide comparable and accurate immunodetection prior to experimental data collection. We found that a commercially available anti-Iba1 antibody, made in goat, produces irregular staining patterns in specific regions of the mouse brain, prompting a further investigation into the phenomenon. This Iba1-goat antibody displayed increased numbers of labeled cells when compared to expression of a CX3CR1-GFP reporter and IHC detection of P2RY12, two common microglial markers. Furthermore, immunodetection by other common anti-Iba1 antibodies made in rabbit and chicken did not display the excessive cell labeling when compared to the CX3CR1-GFP reporter. Upon further investigation, this Iba1-goat antibody was observed to highly colocalize with vasopressin neurons in the paraventricular nucleus of the hypothalamus (PVN) and the supraoptic nucleus of the hypothalamus (SON), the two main sites of vasopressin production in the brain. Other anti-Iba1 antibodies made in other species did not show this same colocalization with vasopressin. Finally, this effect was species-specific, as Wistar rats did not display erroneous cell labeling by the Iba1-goat antibody. In sum, the present study employs both qualitative and quantitative data to highlight the importance of validating antibody efficacy and specificity in a region- and species-specific manner. Significance StatementMicroglia are the primary immune cells of the brain and are involved in many neurodevelopmental, as well as neurodegenerative, processes, thus making the study of microglia an important area of neuroscience research. There is a wide array of antibodies available to label microglia. Specific detection of microglia using immunohistochemistry is crucial for understanding differences in cell density, morphology, and interactions with other cells in various contexts. In the present study, a common anti-Iba1 antibody made in goat was found to display erroneous labeling of vasopressin neurons in specific regions of the mouse brain, inconsistent with other microglial markers, which emphasizes the importance of validating antibody efficacy and specificity in a region- and species-specific manner prior to beginning experimental data collection.

neuroscience↗

bioRxiv2024

Development of 3-in-1 nanotherapeutic strategies for ovarian cancer

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/604002v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@1c2d3e3org.highwire.dtl.DTLVardef@1e4e73eorg.highwire.dtl.DTLVardef@109aceeorg.highwire.dtl.DTLVardef@387843_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOTOCC_FLOATNO C_FIG Among gynecological cancers, ovarian cancer causes the most fatality. Platin-based chemotherapy is the primary therapeutic option, but it is limited by a variety of drug resistance mechanisms. Ovarian cancer is a complex and challenging disease to treat, and combination approaches have shown stronger efficacy than a single drug alone. However, they still need to overcome challenges, such as the non-selective distribution of drugs, and side effects caused by each drug in the combination. To overcome these issues, here we explored a 3-in-1 combination nanotherapeutic approach containing cisplatin, olaparib, and metformin for ovarian cancer. To encapsulate hydrophilic cisplatin and metformin inside the nanoparticle (NP) core, we developed cisplatin polymer prodrugs and metformin derivatives. Our results showed successful development of 3-in-1 NPs containing cisplatin, olaparib, and metformin, and they are stable in the physiological conditions. In vitro evaluation showed each agent in the 3-in-1 NPs is active and exerts therapeutic effects, contributing to ovarian cancer cell killing at lower concentrations. These results provide insight into developing novel nanotherapeutic strategies for improving ovarian cancer treatment.

bioengineering↗

bioRxiv2024

Large- and Small-Animal Studies of Safety, Pharmacokinetics (PK), and Biodistribution of Inflammasome-Targeting Nanoligomer in the Brain and Other Target Organs

Immune malfunction or misrecognition of healthy cells and tissue, termed autoimmune disease, is implicated in more than 80 disease conditions and multiple other secondary pathologies. While pan-immunosuppressive therapies like steroids offer some relief for systemic inflammation for some organs, many patients never achieve remission and such drugs do not cross the blood-brain barrier making them ineffective for tackling neuroinflammation. Especially in the brain, unintended activation of microglia and astrocytes is hypothesized to be directly or indirectly responsible for Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), Parkinsons Disease (PD), and Alzheimers Disease (AD). Recent studies have also shown that targeting inflammasome and specific immune targets can be beneficial for these diseases. Further, our previous studies have shown targeting NF-{kappa}B and NLRP3 through brain penetrant Nanoligomer cocktail SB_NI_112 (abbreviated to NI112) can be therapeutic for several neurodegenerative diseases. Here we show safety-toxicity studies, followed by pharmacokinetics (PK) and biodistribution in small- (mice) and large-animal (dog) studies of this inflammasome-targeting Nanoligomer cocktail NI 112. We conducted studies using four different routes of administration: intravenous (IV), subcutaneous (SQ), intraperitoneal (IP), and intranasal (IN), and identified the drug concentration over time using inductively coupled plasma mass spectrometry (ICP-MS) in the blood serum, the brain (including different brain regions), and other target organs like liver, kidney, and colon. Our results indicate the Nanoligomer cocktail has a strong safety profile, and shows high biodistribution (F [~]0.98) and delivery across multiple routes of administration. Further analysis showed high brain bioavailability with a ratio of NI112 in brain tissue to blood serum [~]30%. Our model accurately shows dose scaling, translation between different routes of administration, and interspecies scaling. These results provide an excellent platform for human clinical translation and predicting therapeutic dosage between different routes of administration.

pharmacology and toxicology↗

bioRxiv2023

Angiotensin-II drives changes in microglia-vascular interactions in rats with heart failure

Activation of microglia, the resident immune cells of the central nervous system, leading to the subsequent release of pro-inflammatory cytokines, has been linked to cardiac remodeling, autonomic disbalance, and cognitive deficits in heart failure (HF). While previous studies emphasized the role of hippocampal Angiotensin II (AngII) signaling in HF-induced microglial activation, unanswered mechanistic questions persist. Evidence suggests significant interactions between microglia and local microvasculature, potentially affecting blood-brain barrier integrity and cerebral blood flow regulation. Still, whether the microglial-vascular interface is affected in the brain during HF remains unknow. Using a well-established ischemic HF rat model, we demonstrate increased vessel-associated microglia (VAM) in HF rat hippocampi, which showed heightened expression of AngII AT1a receptors. Acute AngII administration to sham rats induced microglia recruitment to the perivascular space, along with increased expression of TNFa. Conversely, administering an AT1aR blocker to HF rats prevented the recruitment of microglia to the perivascular space, normalizing their levels to those in healthy rats. These results highlight the critical importance of a rather understudied phenomenon (i.e., microglia-vascular interactions in the brain) in the context of the pathophysiology of a highly prevalent cardiovascular disease, and unveil novel potential therapeutic avenues aimed at mitigating neuroinflammation in cardiovascular diseases.

neuroscience↗

bioRxiv2023

Evaluating ChatGPT as an Agent for Providing Genetic Education

Genetic disorders are complex and can greatly impact an individuals health and well-being. In this study, we assess the ability of ChatGPT, a language model developed by OpenAI, to answer questions related to three specific genetic disorders: BRCA1, MLH1, and HFE. ChatGPT has shown it can supply articulate answers to a wide spectrum of questions. However, its ability to answer questions related to genetic disorders has yet to be evaluated. The aim of this study is to perform both quantitative and qualitative assessments of ChatGPTs performance in this area. The ability of ChatGPT to provide accurate and useful information to patients was assessed by genetic experts. Here we show that ChatGPT answered 64.7% of the 68 genetic questions asked and was able to respond coherently to complex questions related to the three genes/conditions. Our results reveal that ChatGPT can provide valuable information to individuals seeking information about genetic disorders, however, it still has some limitations and inaccuracies, particularly in understanding human inheritance patterns. The results of this study have implications for both genomics and medicine and can inform future developments in this area. AI platforms, like ChatGPT, have significant potential in the field of genomics. As these technologies become integrated into consumer-facing products, appropriate oversight is required to ensure accurate and safe delivery of medical information. With such oversight and training specifically for genetic information, these platforms could have the potential to augment some clinical interactions.

genomics↗

bioRxiv2022

Activated gliosis, accumulation of amyloid beta and hyperphosphorylation of tau in aging canines with and without cognitive decline

Canine cognitive dysfunction (CCD) syndrome is a well-recognized naturally occurring disease in aged dogs, with a remarkably similar disease course, both in its clinical presentation and neuropathological changes, as humans with Alzheimers disease (AD). Similar to human AD patients this naturally occurring disease is found in the aging canine population however, there is little understanding of how the canine brain ages pathologically. It is well known that in neurodegenerative diseases, there is an increase in inflamed glial cells as well as an accumulation of hyperphosphorylation of tau (P-tau) and amyloid beta (A{beta}1-42). These pathologies increase neurotoxic signaling and eventual neuronal loss. We assessed these brain pathologies in aged canines and found an increase in the number of glial cells, both astrocytes and microglia, and the activation of astrocytes indicative of neuroinflammation. A rise in the aggregated protein A{beta}1-42 and hyperphosphorylated tau, at Threonine 181 and 217, in the cortical brain regions of aging canines is seen. We then asked if any of these aged canines had CCD utilizing the only current diagnostic, owner questionnaires, verifying positive or severe CCD had pathologies of gliosis and accumulation of A{beta}1-42 like their aged matched controls. However uniquely the CCD dogs had P-tau at T217. Therefore, this phosphorylation site of tau at threonine 217 may be a predictor for CCD.

neuroscience↗

bioRxiv2022

Targeting neuroinflammatory pathways using Nanoligomer is neuroprotective in prion disease

Neuroinflammation plays a crucial role in the development of neurodegenerative protein misfolding disorders. This category of progressive diseases includes, but is not limited to, Alzheimers disease, Parkinsons disease, and prion diseases. Shared pathogenesis involves the accumulation of misfolded proteins, chronic neuroinflammation, and synaptic dysfunction, ultimately leading to irreversible neuronal loss, measurable cognitive deficits, and death. Presently, there are little to no effective treatments to halt the advancement of neurodegenerative diseases. We hypothesized directly targeting neuroinflammation by downregulating the transcription factor, NF-{kappa}B and the inflammasome protein, NLRP3, with the brain-penetrant, non-toxic, SB_NI_112, would be neuroprotective. To achieve this, we used a cocktail of RNA targeting therapeutics (SB_NI_112) shown to be brain-penetrant, non-toxic, and targeting both NF-|B and NLRP3. We utilized a mouse-adapted prion strain as a model for neurodegenerative diseases to assess aggregation of misfolded proteins, glial inflammation, neuronal loss, cognitive deficits, and lifespan. Prion-diseased mice were treated either intraperitoneally or intranasally with SB_NI_112. Behavioral and cognitive deficits were significantly protected by this combination of NF-{kappa}B and NLRP3 down-regulators. Treatment reduced glial inflammation, protected against neuronal loss, prevented spongiotic change, rescued cognitive deficits, and significantly lengthened lifespan of prion-diseased mice. We have identified a non-toxic, systemic pharmacologic that down-regulates NF-|B and NLRP3, prevents neuronal death and slows the progression of neurodegenerative disease. Though mouse models do not always predict human patient success, and the study was limited due to sample size and number of dosing methods utilized, these findings serve as a proof of principle for continued translation of the therapeutic SB_NI_112 for prion disease and other neurodegenerative diseases. Based on success in a murine prion model, we will be continual testing SB_NI_112 in a variety of neurodegenerative disease models, including Alzheimers Disease and Parkinsons Disease.

neuroscience↗

bioRxiv2020

ES-62 suppression of arthritis reflects epigenetic rewiring of synovial fibroblasts to a joint-protective phenotype

The parasitic worm product, ES-62 protects against collagen-induced arthritis, a mouse model of rheumatoid arthritis (RA) by suppressing the synovial fibroblast (SF) responses perpetuating inflammation and driving joint destruction. Such SF responses are shaped during disease progression by the inflammatory microenvironment of the joint that promotes remodelling of their epigenetic landscape, inducing an "aggressive" pathogenic SF phenotype. Critically, exposure to ES-62 in vivo induces a stably imprinted "safe" phenotype that exhibits responses more typical of healthy SFs. Surprisingly however, DNA methylome analysis reveals that rather than simply preventing the pathogenic rewiring of SFs, ES-62 induces further epigenetic remodelling, including targeting genes associated with ciliogenesis and differentiation, to program a distinct "protective" phenotype. Such unique behaviour signposts potential DNA methylation signatures predictive of pathogenesis and its resolution and hence, candidate mechanisms by which novel therapeutic interventions could prevent SFs from perpetuating joint inflammation and destruction in RA.

pathology↗

bioRxiv2020

A novel sialic acid-binding adhesin present in multiple species contributes to the pathogenesis of infective endocarditis

Bacterial binding to platelets is a key step in the development of infective endocarditis (IE). Sialic acid, a common terminal carbohydrate on host glycans, is the major receptor for streptococci on platelets. So far, all defined interactions between streptococci and sialic acid on platelets are mediated by serine rich repeat proteins (SRRPs). However, we identified Streptococcus oralis subsp. oralis IE-isolates that bind sialic acid but lack SRRPs. In addition to binding sialic acid, some SRRP-negative isolates also bind the cryptic receptor {beta}-1,4-linked galactose through a yet unknown mechanism. Using comparative genomics, we identified a novel sialic acid-binding adhesin, here named AsaA (associated with sialic acid adhesion A), present in IE-isolates lacking SRRPs. We demonstrated that S. oralis subsp. oralis AsaA is required for binding to platelets in a sialic acid-dependent manner. AsaA comprises a non-repeat region (NRR), consisting of a FIVAR/CBM and two Siglec-like and Unique domains, followed by 31 DUF1542 domains. When recombinantly expressed, Siglec-like and Unique domains competitively inhibited binding of S. oralis subsp. oralis and directly interacted with sialic acid on platelets. We further demonstrated that AsaA impacts the pathogenesis of S. oralis subsp. oralis in a rabbit model of IE. Additionally, we found AsaA orthologues in other IE-causing species and demonstrated that the NRR of AsaA from Gemella haemolysans blocked binding of S. oralis subsp. oralis, suggesting that AsaA contributes to the pathogenesis of multiple IE-causing species. Finally, our findings provide evidence that sialic acid is a key factor for bacterial-platelets interactions in a broader range of species than previously appreciated, highlighting its potential as a therapeutic target. Authors summaryInfective endocarditis (IE) is typically a bacterial infection of the heart valves that causes high mortality. Infective endocarditis can affect people with preexisting lesions on their heart valves (Subacute-IE). These lesions contain platelets and other host factors to which bacteria can bind. Growth of bacteria and accumulation of host factors results in heart failure. Therefore, the ability of bacteria to bind platelets is key to the development of IE. Here, we identified a novel bacterial protein, AsaA, which helps bacteria bind to platelets and contributes to the development of disease. Although this virulence factor was characterized in Streptococcus oralis, a leading cause of IE, we demonstrated that AsaA is also present in several other IE-causing bacterial species and is likely relevant to their ability to cause disease. We showed that AsaA binds to sialic acid, a terminal sugar present on platelets, thereby demonstrating that sialic acid serves as a receptor for a wider range of IE-causing bacteria than previously appreciated, highlighting its potential as a therapeutic target.

microbiology↗