Biology subjects

Li, S.-Y.

Publications and source records attributed to Li, S.-Y..

At least 19 recordsLinked to original sources

bioRxiv2026

One-Dose Efficacy of Long-Acting Sorfequiline in a Mouse Model of Tuberculosis Preventive Therapy

Rationale: Tuberculosis preventive therapy (TPT) is essential for global tuberculosis control, yet estimated coverage remains well below global targets. Current World Health Organization (WHO)-recommended regimens require 1-9 months of treatment and are associated with suboptimal completion rates. Long-acting injectable (LAI) formulations offer the potential to improve TPT uptake and completion, with ideal products providing "one-and-done" options via a single administration. Sorfequiline, a second-generation diarylquinoline with superior potency over bedaquiline and lower QT prolongation risk, is a promising candidate for LAI TPT.

microbiology↗

bioRxiv2026

Macrophages regulate meiotic initiation and germ cell clearance in the developing ovary

Tissue-resident macrophages are increasingly recognized for their roles in promoting organogenesis, yet how macrophages are involved in fetal ovarian development remains unclear. In particular, little is known about ovarian macrophage ontogeny and how it relates to germ cell entry into meiosis and establishment of the oocyte reserve. Here we combine temporally-controlled lineage tracing of yolk-sac erythro-myeloid progenitors, fetal HSC-derived progenitors, and postnatal monocytes to map multi-wave seeding and remodeling of ovarian macrophages across fetal and early postnatal life. We identify three major resident subsets defined by MHCII and CSF1R that display distinct expansion kinetics and persistence, and we show that CCR2-dependent monocyte recruitment is required for efficient maturation of postnatal macrophage populations. Functionally, transient or sustained depletion of CSF1R fetal macrophages perturbs ovarian vascular growth and triggers precocious meiotic initiation without overt loss of germ cells, leading to persistent, premature meiotic progression. Extending macrophage depletion into late gestation disrupts perinatal physiological germ cell attrition despite rapid postnatal macrophage repopulation. Together, our findings establish ovarian macrophages as stage-specific regulators that couple immune ontogeny to ovarian morphogenesis and germ cell quality control during establishment of the oocyte reserve. One Sentence SummaryOvarian macrophages are required for the proper timing of germ cell meiotic entry and progression, vascular growth, and for the physiological clearance of germ cells during establishment of the oocyte reserve in perinatal stages.

developmental biology↗

bioRxiv2026

Prenatal corticosteroid exposure disrupts vascular-immune interactions and impairs steroidogenesis in the fetal testis

Antenatal corticosteroid (ACS) therapy, typically using dexamethasone (Dex), is a cornerstone of improving preterm infant survival by accelerating lung maturation. However, its systemic effects on other developing organs remain poorly understood. Here, we reveal a previously unrecognized impact of prenatal Dex exposure on fetal testis development, with implications for long-term male reproductive health. Analysis of fetal testes from a Dex-based ACS mouse model revealed that Dex suppressed androgen synthesis by reducing Leydig cell number and downregulating steroidogenic pathways. Dex also activated immune programs, inducing CD163 M2 macrophages and IL10 signaling, which promoted endothelial expansion. Despite these pro-angiogenic signals, vascular architecture was disrupted: capillary density and pericyte coverage declined, while blood vessel diameter increased. Transcriptomic analyses revealed downregulation of androgen response and cholesterol metabolism pathways, alongside upregulation of immune and coagulation signatures. Analyses of fetal ovaries revealed a sexually dimorphic and organ-specific effect of ACS therapy, in which ovarian gene expression remained unaffected. Our findings uncover an immune-vascular mechanism linking prenatal Dex exposure to impaired steroidogenesis, providing new insight into potentially broad effects of ACS therapy. One Sentence SummaryPrenatal corticosteroid exposure disturbs immune-vascular interactions and suppresses androgen synthesis in the fetal testis, revealing potentially widespread effects of a commonly used therapy.

developmental biology↗

bioRxiv2024

Contribution of telacebec to novel drug regimens in a murine tuberculosis model

The clinical efficacy of combination drug regimens containing the first generation diarylquinoline (DARQ) bedaquiline in the treatment of multidrug-resistant tuberculosis has validated ATP synthesis as a vulnerable pathway in Mycobacterium tuberculosis. New DARQs in clinical development may be even more effective than bedaquiline, including against emerging bedaquiline-resistant strains. Telacebec (T) is a novel cytochrome bc1:aa3 oxidase inhibitor that also inhibits ATP synthesis. Based on its demonstrated efficacy as a monotherapy in mice and in a phase 2a clinical trial, we used an established BALB/c mouse model of tuberculosis (TB) to test the contribution of T to novel combination therapies against two strains of M. tuberculosis (H37Rv and HN878) in an effort to find more effective regimens. Overall, T was more effective in regimens against the HN878 strain than against the H37Rv strain, a finding that supports the greater vulnerability of the former strain to T and to genetic depletion of QcrB. Against both strains, combinations of a DARQ, clofazimine (CFZ), and T were highly bactericidal. However, only against HN878 did T contribute synergistically, whereas an antagonistic effect was observed against H37Rv. These results demonstrate the therapeutic potential of T and highlight how differences in the susceptibility of M. tuberculosis strains could lead to different conclusions about a drugs potential contribution to novel drug regimens.

microbiology↗

bioRxiv2024

Enhanced dynamic covalent chemistry for the controlled release of small molecules and biologics from a nanofibrous peptide hydrogel platform

Maintaining safe and potent pharmaceutical drug levels is often challenging. Multidomain peptides (MDPs) assemble into supramolecular hydrogels with a well-defined, highly porous nanostructure that makes them attractive for drug delivery, yet their ability to extend release is typically limited by rapid drug diffusion. To overcome this challenge, we developed self-assembling boronate ester release (SABER) MDPs capable of engaging in dynamic covalent bonding with payloads containing boronic acids (BAs). As examples, we demonstrate that SABER hydrogels can prolong the release of five BA-containing small-molecule drugs as well as BA-modified insulin and antibodies. Pharmacokinetic studies revealed that SABER hydrogels extended the therapeutic effect of ganfeborole from days to weeks, preventing Mycobacterium tuberculosis growth better than repeated oral administration in an infection model. Similarly, SABER hydrogels extended insulin activity, maintaining normoglycemia for six days in diabetic mice after a single injection. These results suggest that SABER hydrogels present broad potential for clinical translation.

bioengineering↗

bioRxiv2024

Direct inhibitors of InhA with efficacy similar or superior to isoniazid in novel drug regimens for tuberculosis

Isoniazid is an important first-line medicine to treat tuberculosis (TB). Isoniazid resistance increases the risk of poor treatment outcomes and development of multidrug resistance, and is driven primarily by mutations involving katG, encoding the pro-drug activating enzyme, rather than its validated target, InhA. The chemical tractability of InhA has fostered efforts to discover direct inhibitors of InhA (DIIs). During the past five years, successful target engagement and in vivo efficacy have been demonstrated by diverse DIIs. In this study, we bridge the gap in understanding the potential contribution of DIIs to novel combination regimens and demonstrate a clear distinction of DIIs, like GSK693 and the newly described GSK138, from isoniazid, based on activity against clinical isolates and contribution to novel drug regimens. The results presented increase the understanding of DII mechanism of action and provide further impetus to continue exploiting InhA as a promising target for TB drug development.

pharmacology and toxicology↗

bioRxiv2024

A perivascular niche supports endometrial epithelial regeneration

Endometrial regeneration is essential for reproductive cycles and pregnancies, allowing the endometrium to undergo repair and renewal after menstruation and parturition. Epithelial cells lining the uterine cavity are shed during each cycle, although remnant luminal and glandular epithelial cells can regenerate the lumen lining. It is presumed that adult stem/progenitor cells in the uterine stroma also contribute to this regeneration. However, the specific cell type(s) and the underlying mechanisms have not been determined. Herein, we use genetic lineage tracing assays in mice to identify Nestin+ perivascular cells as active contributors to epithelial regeneration. Notch signaling maintains Nestin+ perivascular cells in a quiescent state but these cells re-enter the cell cycle and differentiate into epithelial cells via estrogen-stimulated suppression of Notch signaling dependent on estrogen receptor alpha (ER/ESR1). These findings demonstrate that perivascular cells support epithelial regeneration and reveal a mechanism regulating the quiescence and activation of uterine perivascular cells.

cell biology↗

bioRxiv2024

In vitro and in vivo validation of cwlM and pbpB essentiality for viability and resistance to imipenem in Mycobacterium abscessus

Mycobacterium abscessus lung infection is notoriously difficult to treat due, in part, to the intrinsic resistance of this pathogen to most marketed antibiotics. {beta}-Lactams, namely imipenem and cefoxitin, are first-line drugs in combination regimens used to treat this infection; and there is growing interest in dual-{beta}-lactam-based regimens. Better understanding of the molecular basis of {beta}-lactam activity through study of the genetic determinants of {beta}-lactam susceptibility and tolerance would enable more rational drug combinations and guide discovery of novel drug targets to complement {beta}-lactams. We recently used an inducible CRISPR interference (CRISPRi) system to silence cwlM and pbpB and confirm their essentiality for in vitro growth and resistance to sub-MIC concentrations of imipenem. Here, we extend those findings to show that silencing either gene alone is bactericidal and augments the bactericidal activity of imipenem in vitro. Furthermore, using CRISPRi in a mouse model of M. abscessus lung infection for the first time, we confirm the essentiality of each gene for in vivo survival. These results validate cwlM and pbpB as essential genes and promising drug targets in this pathogen, including for potentiation of carbapenem activity. The results further establish CRISPRi as a powerful method for validating drug targets and studying gene-gene and gene-drug interactions in vitro and in vivo.

microbiology↗

bioRxiv2024

Hyaluronidase impacts exposures of long-acting injectable paliperidone palmitate in rodent models

A significant challenge in the development of long-acting injectable drug formulations, especially for anti-infective agents, is delivering an efficacious dose within a tolerable injection volume. Co-administration of the extracellular matrix-degrading enzyme hyaluronidase can increase maximum tolerable injection volumes but is untested for this benefit with long-acting injectable formulations. One concern is that hyaluronidase could potentially alter the tissue response surrounding an injection depot, a response known to be important for drug release kinetics of long-acting injectable formulations. The objective of this pilot study was to evaluate the impact of co-administration of hyaluronidase on the drug release kinetics, pharmacokinetic profiles, and injection site histopathology of the long-acting injectable paliperidone palmitate for up to four weeks following intramuscular injection in mouse and rat models. In both species, co-administration of hyaluronidase increased paliperidone plasma exposures the first week after injection but did not negate the overall long-acting release nature of the formulation. Hyaluronidase-associated modification of the injection site depot was observed in mice but not in rats. These findings suggest that further investigation of hyaluronidase with long-acting injectable agents is warranted.

pharmacology and toxicology↗

bioRxiv2023

Testis morphogenesis and fetal Leydig cell development are mediated through ERK signaling activated by platelet derived growth factor receptor alpha

Platelet derived growth factor receptor alpha (Pdgfra) plays a crucial role in the morphogenesis and differentiation of the fetal testis, but the molecular signaling involved in these processes remains unclear. Here, we use XY Pdgfra-null knock-in (KI) gonads to investigate the molecular mechanisms underlying Pdgfra-mediated testis cord formation and development of fetal Leydig cells (FLCs). The extracellular signal-regulated kinase (ERK) pathway, a well-known mitogen-activated protein kinase signaling pathway, was significantly inhibited in XY Pdgfra KI gonads, suggesting that ERK signaling is activated downstream of PDGFRA. Using ex vivo whole-organ culture, small interfering RNA (siRNA) cell culture methods, transwell assays and a genetic mouse model to disrupt ERK signaling in gonadal cells, we found that the ERK pathway promoted testis cord formation via early growth response 1 (Egr1)-mediated cell migration and regulated the expression of steroidogenic enzymes in FLCs via activating the transcription factor cAMP responsive element binding protein 1 (CREB; official name CREB1). These findings highlight the significance of PDGFRA and its downstream signaling in fetal testis morphogenesis and cellular differentiation, thus providing insights into the etiology of and potential therapeutic targets for disorders related to gonadal development.

developmental biology↗

bioRxiv2023

Contezolid can replace linezolid in a novel combination with bedaquiline and pretomanid in a murine model of tuberculosis

Contezolid is a new oxazolidinone with in vitro and in vivo activity against Mycobacterium tuberculosis comparable to that of linezolid. Pre-clinical and clinical safety studies suggest it may be less toxic than linezolid, making contezolid a potential candidate to replace linezolid in treatment of drug-resistant tuberculosis. We evaluated the dose-ranging activity of contezolid, alone and in combination with bedaquiline and pretomanid, and compared it with linezolid at similar doses, in an established BALB/c mouse model of tuberculosis. Contezolid had an MIC of 1 {micro}g/ml, similar to linezolid, and exhibited similar bactericidal activity in mice. Contezolid-resistant mutants selected in vitro had 10-fold increases in contezolid MIC and harbored mutations in the mce3R gene. These mutants did not display cross-resistance to linezolid. Our results indicate that contezolid has potential to replace linezolid in regimens containing bedaquiline and pretomanid and likely other regimens.

microbiology↗

bioRxiv2023

Subtype-specific circadian clock dysregulation modulates breast cancer biology, invasiveness, and prognosis.

Studies in shift workers and model organisms link circadian disruption to breast cancer. However, molecular rhythms in non-cancerous and cancerous human breast tissues are largely unknown. We reconstructed rhythms informatically, integrating locally collected, time-stamped biopsies with public datasets. For non-cancerous tissue, the inferred order of core-circadian genes matches established physiology. Inflammatory, epithelial-mesenchymal transition (EMT), and estrogen responsiveness pathways show circadian modulation. Among tumors, clock correlation analysis demonstrates subtype-specific changes in circadian organization. Luminal A organoids and informatic ordering of Luminal A samples exhibit continued, albeit disrupted rhythms. However, CYCLOPS magnitude, a measure of global rhythm strength, varied widely among Luminal A samples. Cycling of EMT pathway genes was markedly increased in high-magnitude Luminal A tumors. Patients with high-magnitude tumors had reduced 5-year survival. Correspondingly, 3D Luminal A cultures show reduced invasion following molecular clock disruption. This study links subtype-specific circadian disruption in breast cancer to EMT, metastatic potential, and prognosis.

cancer biology↗

bioRxiv2023

Using dynamic oral dosing of rifapentine and rifabutin to simulate exposure profiles of long-acting formulations in a mouse model of tuberculosis preventive therapy

Administration of tuberculosis preventive therapy (TPT) to individuals with latent tuberculosis infection is an important facet of global tuberculosis control. The use of long-acting injectable (LAI) drug formulations may simplify and shorten regimens for this indication. Rifapentine and rifabutin have anti-tuberculosis activity and physiochemical properties suitable for LAI formulation, but there are limited data available for determining the target exposure profiles required for efficacy in TPT regimens. The objective of this study was to determine exposure-activity profiles of rifapentine and rifabutin to inform development of LAI formulations for TPT. We utilized a validated paucibacillary mouse model of TPT in combination with dynamic oral dosing of both drugs to simulate and understand exposure-activity relationships to inform posology for future LAI formulations. This work identified several LAI-like exposure profiles of rifapentine and rifabutin that, if achieved by LAI formulations, could be efficacious as TPT regimens and thus can serve as experimentally-determined targets for novel LAI formulations of these drugs. We present novel methodology to understand the exposure-response relationship and inform the value proposition for investment in development of LAI formulations that has utility beyond latent tuberculosis infection.

microbiology↗

bioRxiv2023

Next-generation diarylquinolines improve sterilizing activity of regimens with pretomanid and the novel oxazolidinone TBI-223 in a mouse tuberculosis model

A regimen comprised of bedaquiline, pretomanid and linezolid (BPaL) is the first oral 6-month regimen approved by the US Food and Drug Administration and recommended by the World Health Organization for treatment of extensively drug-resistant tuberculosis. We used a well-established BALB/c mouse model of tuberculosis to evaluate the treatment-shortening potential of replacing bedaquiline with either of two new, more potent diarylquinolines in early clinical trials, TBAJ-587 and TBAJ-876. We also evaluated the effect of replacing linezolid with a new oxazolidinone, TBI-223, exhibiting a larger safety margin with respect to mitochondrial toxicity in preclinical studies. Replacing bedaquiline with TBAJ-587 at the same 25 mg/kg dose significantly reduced the proportion of mice relapsing after 2 months of treatment, while replacing linezolid with TBI-223 at the same 100 mg/kg dose did not significantly change the proportion of mice relapsing. Replacing linezolid or TBI-223 with sutezolid in combination with TBAJ-587 and pretomanid significantly reduced the proportion of mice relapsing. In combination with pretomanid and TBI-223, TBAJ-876 at 6.25 mg/kg was equipotent to TBAJ-587 at 25 mg/kg. We conclude that replacement of bedaquiline with these more efficacious and potentially safer diarylquinolines and replacement of linezolid with potentially safer and at least as efficacious oxazolidinones in the clinically successful BPaL regimen may lead to superior regimens capable of treating both drug-susceptible and drug-resistant TB more effectively and safely.

microbiology↗

bioRxiv2022

Mangroves deviate from other angiosperms in their genome size, leaf cell size, and cell packing density relationships

Background and AimsWhile genome size limits the minimum sizes and maximum numbers of cells that can be packed into a given leaf volume, mature cell sizes can be substantially larger than their meristematic precursors and vary in response to abiotic conditions. Mangroves are iconic examples of how abiotic conditions can influence the evolution of plant phenotypes. MethodsHere, we examined the coordination between genome size, leaf cell sizes, and cell packing densities, and leaf size in 13 mangrove species across four sites. Four of these species occurred at more than one site, allowing us to test the effect of climate on leaf anatomy. ResultsWe found that genome sizes of mangroves were very small compared to other angiosperms, and, like other angiosperms, mangrove cells were always larger than the minimum size defined by genome size. Increasing mean annual temperature of a growth site led to higher packing densities of veins (Dv) and stomata (Ds) and smaller epidermal cells but had no effect on stomatal size. Contrary to other angiosperms, mangroves exhibited (1) a negative relationship between guard cell size and genome size; (2) epidermal cells that were smaller than stomata, and (3) coordination between Dv and Ds that was not mediated by epidermal cell size. Furthermore, mangrove epidermal cell sizes and packing densities covaried with leaf size. ConclusionsWhile mangroves exhibited coordination between veins and stomata and attained a maximum theoretical stomatal conductance similar to other angiosperms, the tissue-level tradeoffs underlying these similar relationships across species and environments was markedly different, perhaps indicative of the unique structural and physiological adaptations of mangroves to their stressful environments.

ecology↗

bioRxiv2022

GSK2556286 is a novel antitubercular drug candidate effective in vivo with the potential to shorten tuberculosis treatment

As a result of a high-throughput compound screening campaign of Mycobacterium tuberculosis infected macrophages, a new preclinical drug candidate for the treatment of tuberculosis has been identified. GSK2556286 inhibits growth within human macrophages (IC50 = 0.07 {micro}M), is active against extracellular bacteria in cholesterol-containing culture media and exhibits no cross-resistance with known antitubercular drugs. In addition, it has shown efficacy in different mouse models of tuberculosis (TB) and has an adequate safety profile in two preclinical species. These features indicate a compound with a novel mode of action, although still not fully defined, that is effective against both multidrug or extensively-resistant (M/XDR) and drug-sensitive (DS) M. tuberculosis with the potential to shorten the duration of treatment in novel combination drug regimens. One Sentence SummaryGSK2556286 is a novel preclinical drug candidate for the treatment of tuberculosis with a new mode of action potentially able to contribute to the shortening of TB chemotherapy.

pharmacology and toxicology↗

bioRxiv2021

Perivascular cells support folliculogenesis in the developing ovary

Granulosa cells, supporting cells of the ovary, are essential for ovarian differentiation by providing a nurturing environment for oogenesis. Sufficient numbers of granulosa cells are vital for establishment of follicles and the oocyte reserve; therefore, identifying the cellular source from which granulosa cells are derived is critical for understanding basic ovarian biology. One cell type that has received little attention in this field is the perivascular cell. Here we use lineage tracing and organ culture techniques in mice to identify ovarian Nestin+ perivascular cells as multipotent progenitors that contribute to granulosa, thecal, and pericyte lineages. Maintenance of these progenitors was dependent on vascular-mesenchymal Notch signaling. Ablation of postnatal Nestin+ cells resulted in a disruption of granulosa cell specification and an increased incidence of polyovular ovarian follicles, thus uncovering key roles for vasculature in ovarian differentiation. These findings may provide new insights into the origins of female gonad dysgenesis and infertility.

developmental biology↗

bioRxiv2021

Loss of Mafb and Maf distorts myeloid cell ratios and disrupts fetal mouse testis vascularization and organogenesis

Testis differentiation is initiated when Sry in pre-Sertoli cells directs the gonad toward a male-specific fate. Sertoli cells are essential for testis development, but cell types within the interstitial compartment, such as immune and endothelial cells, are also critical for organ formation. Our previous work implicated macrophages in fetal testis morphogenesis, but little is known about genes underlying immune cell development during organogenesis. Here we examine the role of the immune-associated genes Mafb and Maf in mouse fetal gonad development, and we demonstrate that deletion of these genes leads to aberrant hematopoiesis manifested by supernumerary gonadal monocytes. Mafb;Maf double knockout embryos underwent initial gonadal sex determination normally, but exhibited testicular hypervascularization, testis cord formation defects, Leydig cell deficit, and a reduced number of germ cells. In general, Mafb and Maf alone were dispensable for gonad development; however, when both genes were deleted, we observed significant defects in testicular morphogenesis, indicating that Mafb and Maf work redundantly during testis differentiation. These results demonstrate previously unappreciated roles for Mafb and Maf in immune and vascular development and highlight the importance of interstitial cells in gonadal differentiation. Summary statementDeletion of Mafb and Maf genes leads to supernumerary monocytes in fetal mouse gonads, resulting in vascular, morphogenetic, and differentiation defects during testicular organogenesis.

developmental biology↗