Biology subjects

Tran, Y.

Publications and source records attributed to Tran, Y..

3 recordsLinked to original sources

bioRxiv2026

Fluid shear stress has a biphasic effect on clathrin-mediated endocytosis in vascular endothelial cells

Vascular endothelial cells (ECs) form a monolayer lining blood vessels and serve as a barrier between blood and tissues. Clathrin-mediated endocytosis (CME) is a major internalization pathway that involves a physical conformational change of the plasma membrane to form a vesicle and is therefore sensitive to the local environment. ECs are subjected to a myriad of fluid shear stress (FSS) rates from circulating blood, which we hypothesize affects CME. To test this, we used simultaneous two-wavelength axial ratiometry (STAR) microscopy, which provides nanoscale axial resolution, to determine the frequency and morphology of clathrin-coated vesicles as they form. Human umbilical vein endothelial cells (HUVECs) were transfected with dual-tagged clathrin light chain a (CLCa-iRFP-EGFP) and cultured under 10 dyn/cm2 FSS. CME activity was elevated in cells cultured under flow and assayed in static or flow conditions compared to statically cultured and imaged controls, indicating that FSS-induced changes to CME were maintained shortly after flow cessation. Single vesicle analysis showed cells cultured in FSS had a slight preference for vesicle formation with a flat-to-curved clathrin transition compared to control. Next, to assess the impact of different FSS rates, we cultured HUVECs at 20 and 40 dyn/cm2 FSS. We found total CME frequency was elevated compared to control at 20 dyn/cm2, but not 40 dyn/cm2. HUVECs cultured at both 20 and 40 dyn/cm2 had vesicles with increased lifetime and enhanced stability, as well as a higher proportion of vesicles formed through a flat-to-curved transition of clathrin.

Cell Biology↗

bioRxiv2026

Pre-clinical efficacy of a C4BP hexameric IgG Fc fusion protein against Neisseria gonorrhoeae

Gonorrhea is the second most common bacterial sexually transmitted infection and affects about 80 million people worldwide annually. The causative agent, Neisseria gonorrhoeae, has become resistant to almost every antibiotic used for its treatment. There is no licensed vaccine against gonorrhea. Therefore, there is an urgent need to develop novel prevention and treatment strategies to curb the spread of gonorrhea. The gonococcus has evolved several mechanisms to evade complement, a key arm of immune defenses against this pathogen, including binding of the human complement inhibitors Factor H (FH) and C4b-binding protein (C4BP). We previously showed that chimeric molecules fusing the gonococcal binding domains of FH and C4BP to IgG Fc and IgM Fc, respectively, mediate complement-dependent killing of gonococci in vitro and attenuate gonococcal colonization of mouse vaginas when administered topically. Here, we fused C4BP domains 1 and 2, which contain the gonococcal binding region, to IgG Fc bearing the IgM tail-piece to facilitate Fc hexamerization. This molecule, called C4BP-Hexa IgG Fc, showed [~]650-fold greater complement-dependent bactericidal activity on a molar basis than monomeric C4BP-IgG1 Fc. C4BP-Hexa IgG Fc enhanced association with and uptake by human neutrophils in a complement-independent manner. Despite off-target complement activation in solution, C4BP-Hexa IgG Fc reduced both the duration and the bacterial burden of gonococcal vaginal colonization in human FH and C4BP transgenic mice when administered intravaginally daily. In conclusion, we show proof-of-concept of the efficacy of a hexameric C4BP IgG Fc fusion molecule against N. gonorrhoeae, which could aid in the fight against this multidrug-resistant pathogen.

immunology↗

bioRxiv2024

Complement therapeutic Factor H-IgG proteins as pre-exposure prophylaxes against Lyme borreliae infections

Lyme disease (LD) is the most common vector-borne disease in the northern hemisphere and is caused by the bacteria Borrelia burgdorferi sensu lato (also known as Lyme borreliae) with no effective prevention available. Lyme borreliae evade complement killing, a critical arm of host immune defense, by producing outer surface proteins that bind to a host complement inhibitor, factor H (FH). These outer surface proteins include CspA and CspZ, which bind to the 6th and 7th short consensus repeats of FH (SCR(6-7)), and the OspE family of proteins (OspE), which bind to the 19th and 20th SCR (SCR19-20). In this study, we produced two chimeric proteins, FH-Fc, containing the Fc region of immunoglobulin G (Fc) with SCR(6-7) or SCR(19-20). We found that both FH-Fc constructs killed B. burgdorferi in the presence of complement and reduced bacterial colonization and LD-associated joint inflammation in vivo. While SCR(6-7)-Fc displayed Lyme borreliae species-specific bacterial killing, SCR(19-20)-Fc versatilely eradicated all tested bacterial species/strains. This correlated with SCR(6-7)-Fc binding to select variants of CspA and CspZ, but SCR(19-20)-Fc binding to all tested OspE variants. Overall, we demonstrated the concept of using FH-Fc constructs to kill Lyme borreliae and defined underlying mechanisms, highlighting the potential of FH-Fc as a pre-exposure prophylaxis against LD infection. AUTHOR SUMMARYTransmitted by ticks, Lyme disease (LD) is the most common vector-borne disease in North America and has experienced an expanded geographical range and increasing number of cases in recent years. No effective prevention is currently available. The causative agent of LD, Borrelia burgdorferi sensu lato (Bbsl), is a complex containing a variety of species. To escape from killing by complement, one of the mammalian host defense mechanisms, Bbsl produces outer surface proteins that bind to a complement inhibitor, factor H (FH). These FH-binding proteins (i.e., CspA, CspZ, and OspE) evade complement by recruiting FH to the bacterial surface. Here we produced two FH-Fc fusion proteins, which combine human immunoglobulin Fc with the human FH domains that bind to Bbsl FH-binding proteins. We found that FH-Fc constructs kill Bbsl in vitro and prevent colonization and LD manifestations in murine models, correlating with these FH-Fc constructs ability to bind to CspA, CspZ, and OspE from respective Bbsl species. These results suggest the possibility of using FH-Fc as a prevention against LD.

microbiology↗