Biology subjects

Man, S.

Publications and source records attributed to Man, S..

5 recordsLinked to original sources

bioRxiv2025

Identification of allo- or orthosteric VHH/single-domain antibodies that enhance or block pathogen binding to Siglec-1 on dendritic cells

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC="FIGDIR/small/695420v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@e85819org.highwire.dtl.DTLVardef@1eff6b4org.highwire.dtl.DTLVardef@12daa92org.highwire.dtl.DTLVardef@11959e5_HPS_FORMAT_FIGEXP M_FIG C_FIG BackgroundSiglec-1 (Sialoadhesin/CD169) is expressed on myeloid cells and plays a key role in host defences by capturing incoming sialylated-pathogens such as Campylobacter jejuni. However, binding to Siglec-1 has also been exploited by pathogens such as SARS-CoV-2 for further dissemination. ResultsHere we identified high-affinity VHHs also known as single-domain antibodies or Nanobodies that bind to Siglec-1 and allo- or orthosterically modulate ligand binding. VHH 2C2 was shown to bind directly to the ligand binding site of Siglec-1 and blocked binding of ganglioside liposomes and Campylobacter jejuni to monocyte-derived dendritic cells (moDCs) and ex vivo Siglec-1+ DCs. VHH 2C2 also blocked SARS-CoV-2 binding of moDCs. In contrast, the VHHs 1B5 and 1C1 interacted with Siglec-1 outside the ligand binding site and acted as positive allosteric modulators of Siglec-1 ligand interactions, as was illustrated by increased ganglioside liposome and Campylobacter jejuni binding by moDCs. Our data suggests that mechanistically, the VHH 1B5 and 1C1 interfere with the cis-binding sialic acids present on the Siglec-1-expressing cell and thereby enhance trans-interactions with ligands. ConclusionIn conclusion, we have isolated VHH that enhance or block Siglec-1 ligand binding to a variety of sialylated-pathogens enabling further interrogation of Siglec-1 function. Moreover, unlike conventional blocking antibodies targeting specific pathogens, Siglec-1 binding VHH could potentially serve as broad-spectrum pathogen blocking agents.

immunology↗

bioRxiv2025

Chimeric Collagen-like Proteins with Tunable Structural Heterogeneity for Precise Control and Targeted Doxorubicin Delivery

Protein-based drug delivery systems offer advantages such as genetic tunability, structural homogeneity, and high biocompatibility. However, precisely controlling the assembly of protein nanoparticles and establishing correlations between their macroscopic properties and molecular architecture remain significant challenges. Here, inspired by chimeric collagen-like proteins, we rationally designed a series of de novo chimeric proteins comprising an N-terminal globular domain fused to a linear collagen-like domain. These structurally heterogeneous proteins were conjugated with doxorubicin (DOX) and homogenized to form chimeric collagen-like protein-DOX nanocomplexes (CDCNs). By fine-tuning the protein structure and domain organization, we achieved precise control over CDCN architecture and drug release kinetics. Furthermore, to enhance tumor specificity, triple-negative breast cancer (TNBC)- and glioblastoma (GBM)-targeting peptides were genetically fused to the chimeric proteins, respectively. In both in vitro and in vivo models of TNBC and GBM, CDCNs facilitated selective tumor accumulation, enhanced cellular uptake, and promoted apoptosis while minimizing off-target toxicity. This work establishes a strategy for designing protein-based nanoplatforms with programmable structures and tunable functionalities, offering promising potential for precisely controlling of protein-based delivery system.

bioengineering↗

bioRxiv2024

Determination of Capsaicin content and pungency levels in Dalle Khursani accessions, a polyploid Capsicum species specific to Darjeeling-Sikkim Himalaya, India

The genus Capsicum includes more than 30 species, of which only five are cultivated. The pungency in chillies is primarily due to the accumulation of capsaicinoids such as capsaicin and dihydrocapsaicin, which varies significantly among species and varieties. Dalle Khursani, a unique landrace of Capsicum sp specific to the Darjeeling-Sikkim Himalaya in India, is highly valued for its pungency. However, very limited research exists on the variation of capsaicin content across different accessions of Dalle Khursani. The present study was undertaken to evaluate the capsaicin content and pungency levels of seven accessions collected from diverse altitudinal locations. High-Performance Liquid Chromatography (HPLC) was used to quantify capsaicin content. The concentration of capsaicin varied between 19.05 mg/g to 28.54 mg/g with the corresponding Scoville Heat Units (SHU) ranging from 304,863 to 456,636 revealing the presence of significant variations for pungency within the accessions of Dalle Khursani that may be attributed to genetic or environmental factors. Accessions DK-02 and DK-03 exhibited the highest capsaicin levels despite differing altitudinal growing environments. The results suggest a strong genetic influence on capsaicinoid content, with environmental factors playing a lesser role. For the first time, the capsaicin content and pungency levels in Dalle Khursani accessions are reported in this study.

plant biology↗

bioRxiv2023

Genetically Encodable in situ Gelation Redox-Responsive Collagen-Like Protein Hydrogel for Accelerating Diabetic Wound Healing

Genetically encoded collagen-like protein-based hydrogels have demonstrated remarkable efficacy in promoting the healing process in diabetic patients. However, the current methods for preparing these hydrogels pose significant challenges due to harsh reaction conditions and the reliance on chemical crosslinkers. In this study, we present a genetically encoded approach that allows for the creation of protein hydrogels without the need for chemical additives. Our design involves the genetic encoding of paired-cysteine residues at the C- and N-terminals of a meticulously engineered collagen-like recombination protein. The protein-based hydrogel undergoes a gel-sol transition in response to redox stimulation, achieving a sol-gel transition. We provide evidence that the co-incubation of the protein hydrogel with 3T3 cells not only enhances cell viability but also promotes cell migration. Moreover, the application of the protein hydrogel significantly accelerates the healing of diabetic wounds by upregulating the expression of COL-1 and CK-14, while simultaneously reducing oxidant stress in the wound microenvironment. Our study highlights a straightforward and chemical-free strategy for the preparation of redox-responsive protein hydrogels. Importantly, our findings underscore the potential of this hydrogel system for effectively treating diabetic wounds, offering a promising avenue for future therapeutic applications.

bioengineering↗

bioRxiv2022

First-in-human evaluation of cutaneous innate and adaptive immunomodulation by mosquito bites

Mosquito-borne viruses are a growing global threat. Initial viral inoculation occurs in the skin via the mosquito bite, eliciting immune responses that shape the establishment of infection and pathogenesis. We aimed to cutaneous innate and adaptive immune responses to mosquito bites in individuals from endemic areas. In this single-arm, cross-sectional interventional study, we enrolled 30 healthy adult participants aged 18 to 45 years of age from Cambodia between October 2020 and January 2021. We performed 3-mm skin biopsies at baseline as well as 30 minutes, 4 hours, and 48 hours after a controlled feeding by uninfected Aedes aegypti mosquitos. The primary endpoints were measurement of changes in early and late innate responses in bitten vs unbitten skin by gene expression profiling, immunophenotyping, and cytokine profiling. Results revealed induction of neutrophil degranulation and recruitment of skin-resident dendritic cells and M2-macrophages in bitten skin. As the immune reaction progressed over time, T cell priming and regulatory pathways were upregulated along with a shift to a Th2-driven response and CD8+ T cell activation. In accordance, participants bitten skin cells produced less pro-inflammatory cytokines when stimulated by Ae. aegypti salivary gland extract. No unexpected adverse events occurred, and one patient was lost to follow-up at Day 14. These results identify key immune genes, cell types, and pathways in the human response to mosquito bites that can be leveraged to develop novel therapeutics and vector-targeted vaccine candidates to arboviral diseases. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/489145v2_ufig1.gif" ALT="Figure 1"> View larger version (77K): org.highwire.dtl.DTLVardef@1ba2eaaorg.highwire.dtl.DTLVardef@4d9dd6org.highwire.dtl.DTLVardef@1b54dc8org.highwire.dtl.DTLVardef@5a104_HPS_FORMAT_FIGEXP M_FIG Panel shows evolution of the human skin response to Aedes aegypti bites over time. C_FIG

immunology↗