Biology subjects

Tun, H. M.

Publications and source records attributed to Tun, H. M..

4 recordsLinked to original sources

bioRxiv2026

Isoleucine and asparagine influence the growth of staphylococcal strains in atopic dermatitis

Atopic dermatitis (AD) is a multifactorial, chronic skin disease associated with microbial factors. It is known that staphylococcal skin microbes play a role in the pathophysiology of AD, notably S. aureus. However, how staphylococcal strain variation affects disease aetiology and progression remains unclear. Using a culture-dependent approach, we analyzed the genomic and phenotypic profile of staphylococcal strains isolated from a Hong Kong children cohort (n = 70). Presence of S. aureus was positively associated with AD skin, whilst S. epidermidis and S. hominis were positively associated with healthy skin, but no overall strain type was associated with AD. In vitro experimentation revealed that there is demarcation in S. aureus strain growth, biofilm biomass formation, and metabolite production by disease severity. While isoleucine and asparagine promoted S. aureus growth, these amino acids suppressed S. hominis growth. These collective findings highlight the importance of strain-level and metabolic interactions of staphylococci in AD pathophysiology.

microbiology↗

bioRxiv2026

TRIM21 is a molecular rheostat for influenza A virus replication

TRIM21 is a multifunctional E3 ubiquitin ligase and intracellular antibody receptor, yet its role during viral infection remains unclear, with reports describing both antiviral and proviral activities. Here, we show that TRIM21 regulates influenza infection in an expression-dependent manner by functioning as a molecular rheostat rather than a binary restriction factor. This graded activity of TRIM21, which leads to both suppression and promotion of influenza replication, couples linkage-specific ubiquitination of viral nucleoprotein with modulation of innate immune signaling. Additionally, loss of TRIM21 unmasks a compensatory antiviral program centered on PRKDC, which is a ubiquitination target of TRIM21. This positions PRKDC as a latent restriction factor selectively engaged when primary TRIM21 control is lost. Together, these findings reveal a hierarchical and plastic antiviral network in which TRIM21 sets an adjustable threshold for host defense while restraining secondary restriction pathways. This framework highlights the sophisticated layers of regulation of the host ubiquitin-mediated antiviral immunity.

cell biology↗

bioRxiv2022

Age-related seroprevalence trajectories of seasonal coronaviruses in children

Four seasonal coronaviruses, including HCoV-NL63 and HCoV-229E, HCoV-OC43 and HCoV-HKU1 cause approximately 15-30% of common colds in adults. However, the frequency and timing of early infection with four seasonal coronaviruses in the infant are still not well studied. Here, we evaluated the serological response to four seasonal coronaviruses in 1886 children under 18-year-old to construct the viral infection rates. The antibody levels were also determined from the plasma samples of 485 pairs postpartum women and their newborn babies. This passive immunity waned at one year after birth and the resurgence of the IgGs were found thereafter with the increase of the age. Taken together, our results show the age-related seroprevalence trajectories of seasonal coronaviruses in children and provide useful information for deciding vaccine strategy for coronaviruses in the future.

immunology↗

bioRxiv2018

Effects of exclusive breastfeeding on infant gut microbiota: a meta-analysis across studies and populations

Literature regarding the differences in gut microbiota between exclusively breastfed (EBF) and non-EBF infants is meager with large variation in methods and results. We performed a meta-analysis of seven studies (a total of 1825 stool samples from 684 infants) to investigate effects of EBF compared to non-EBF on infant gut microbiota across different populations. In the first 6 months of life, overall bacterial diversity, gut microbiota age, relative abundances of Bacteroidetes and Firmicutes and microbial-predicted pathways related to carbohydrate metabolism were consistently increased; while relative abundances of pathways related to lipid, vitamin metabolism and detoxification were decreased in non-EBF vs. EBF infants. The perturbation in microbial-predicted pathways associated with non-EBF was larger in infants delivered by C-section than delivered vaginally. Longer duration of EBF mitigated diarrhea-associated gut microbiota dysbiosis and the effects of EBF persisted after 6 months of age. These consistent findings across vastly different populations suggest that one of the mechanisms of short and long-term benefits of EBF may be alteration in gut microbes.

microbiology↗