Biology subjects

Machan, J. T.

Publications and source records attributed to Machan, J. T..

4 recordsLinked to original sources

bioRxiv2025

Neutrophil progenitor cell therapy rescues host defense against Staphylococcus aureus in murine chronic granulomatous disease

Despite advances in engineered adaptive immune cell therapies, current options for innate immune cell therapies are sparse. In this work, we demonstrate the utility of a neutrophil progenitor-based cell therapy. Murine conditionally-immortalized neutrophil progenitors (NPs) overcome the hurdles of alternative cell therapies by engrafting in the unconditioned host and substantially contributing to the host neutrophil population. Here we demonstrate the therapeutic value of NPs using a murine model of the primary immunodeficiency chronic granulomatous disease (CGD). Those with CGD are highly susceptible to infection with Staphylococcus aureus because of genetic mutations that impair neutrophil antimicrobial function. We find that the prophylactic treatment of CGD mice with transfused NPs rescue them from an otherwise lethal S. aureus pulmonary infection. In investigating the mechanisms behind the improved clearance of S. aureus and survival of CGD mice, our data suggests that the antimicrobial function of host CGD neutrophils is rescued by the presence of donor-derived wild-type neutrophils. We also observe that survival is improved to >50% in the CGD model when mice receive NPs post-infection. This work highlights the application of NPs to improving outcomes to acute bacterial infection in CGD, demonstrating the translational potential of conditionally-immortalized myeloid progenitors as a cellular therapy.

immunology↗

bioRxiv2021

Pre-mRNA processing entropy in a mouse model of trauma

PurposeNext generation sequencing has expanded our understanding of many disease processes, including trauma and critical illness. Many studies focus identifying a small set of genes or proteins that are aberrantly expressed. Our objective was to determine whether global differences in pre-mRNA processing entropy, or disorder, could offer novel insights in the setting of critical illness. MethodsWe used an established murine model of trauma that consisted of hemorrhagic shock and cecal ligation and puncture. In our first experiment mice exposed to trauma were compared to controls. In our second experiment, survival 14 days after exposure to trauma was studied. Using deep RNA sequencing we determined entropy values for every pre-mRNA processing event identified. We then used principal component analysis (PCA) to conduct unsupervised classification of the data. ResultsMice exposed to trauma separated from controls using PCA. Similarly, mice that did not survive 14 days post exposure clustered closely together on PCA. ConclusionOur results suggest that there is a substantial difference in global pre-mRNA processing entropy in mice exposed to trauma vs. controls, and that pre-mRNA processing entropy may be helpful in predicting mortality. The method introduced here is easily transferrable to other disease processes and samples.

genomics↗

bioRxiv2021

Chitinase 3-like-1 is a Therapeutic Target That Mediates the Effects of Aging in COVID-19

COVID-19 is caused by the SARS-CoV-2 (SC2) virus and is more prevalent and severe in the elderly and patients with comorbid diseases (CM). Because chitinase 3-like-1 (CHI3L1) is induced during aging and CM, the relationships between CHI3L1 and SC2 were investigated. Here we demonstrate that CHI3L1 is a potent stimulator of the SC2 receptor ACE2 and viral spike protein priming proteases (SPP), that ACE2 and SPP are induced during aging and that anti-CHI3L1, kasugamycin and inhibitors of phosphorylation, abrogate these ACE2- and SPP-inductive events. Human studies also demonstrated that the levels of circulating CHI3L1 are increased in the elderly and patients with CM where they correlate with COVID-19 severity. These studies demonstrate that CHI3L1 is a potent stimulator of ACE2 and SPP; that this induction is a major mechanism contributing to the effects of aging during SC2 infection and that CHI3L1 coopts the CHI3L1 axis to augment SC2 infection. CHI3L1 plays a critical role in the pathogenesis of and is an attractive therapeutic target in COVID-19.

immunology↗

bioRxiv2016

Quantitative Analysis of Dopamine Neuron Subtypes Generated from Mouse Embryonic Stem Cells

Dopamine (DA) neuron subtypes modulate specific physiological functions and are involved in distinct neurological disorders. Embryonic stem cell (ESC) derived DA neurons have the potential to aid in the study of disease mechanisms, drug discovery, and possibly cell replacement therapies. DA neurons can be generated from ESCs in vitro, but the subtypes of ESC-derived DA neurons have not been investigated in detail despite the diversity of DA neurons observed in vivo. Due to cell culture heterogeneity, sampling methods applied to ESC-derived cultures can be ambiguous and potentially biased. Therefore, we developed a quantification method to capture the depth of DA neuron production in vitro by estimating the error associated with systematic random sampling. Using this method, we quantified calbindin+ and calretinin+ subtypes of DA neurons generated from mouse ESCs. We found a higher production of the calbindin+ subtype (11-27%) compared to the calretinin+ subtype (2-13%) of DA neuron; in addition, DA neurons expressing neither subtype marker were also generated. We then examined whether exogenous sonic hedgehog (SHH) and fibroblast growth factor 8 (FGF8) affected subtype generation. Our results demonstrate that exogenous SHH and FGF8 did not alter DA neuron subtype generation in vitro. These findings suggest that a deeper understanding DA neuron derivation inclusive of mechanisms that govern the in vitro subtype specification of ESC-derived DA neurons is required.\n\nNoteAll research was planned and conducted while members were at Brown University\n\nResearch fundingNIH/NCRR/NIGMS RI Hospital COBRE Center for Stem Cell Biology (8P20GM103468-04) (MZ) Brown Institute for Brain Science Pilot Grant (4-63662) (MZ/DHK)

neuroscience↗