Publications by authors named "Cheol-Heui Yun"

Respiratory syncytial virus (RSV) causes symptoms similar to a mild cold for adults, but in case of infants, it causes bronchitis and/or pneumonia, and in some cases, mortality. Mucosal immunity within the respiratory tract includes tissue-resident memory T (T) cells and tissue-resident memory B (B) cells, which provides rapid and efficient protection against RSV re-infection. Therefore, vaccine strategies should aim to generate mucosal immune responses.

View Article and Find Full Text PDF

Probiotics are known to have favorable effects on human health. Nevertheless, probiotics are not always beneficial and can cause unintended adverse effects such as bacteremia and/or inflammation in immunocompromised patients. In the present study, we investigated the effects of probiotics on the regulation of bone metabolism under different health conditions and delivery routes.

View Article and Find Full Text PDF

Lipoteichoic acid (LTA) and peptidoglycan (PGN) are considered as key virulence factors of , which is a representative sepsis-causing Gram-positive pathogen. However, cooperative effect of LTA and PGN on nitric oxide (NO) production is still unclear despite the pivotal roles of NO in initiation and progression of sepsis. We here evaluated the cooperative effects of LTA (SaLTA) and muramyl dipeptide (MDP), the minimal structure of PGN, on NO production in both a mouse macrophage-like cell line, RAW 264.

View Article and Find Full Text PDF

Unlabelled: is a prevalent opportunistic pathogenic fungus that resides in the skin and gastrointestinal (GI) tract of humans. Under specific conditions, cells transition from a commensal to a pathogenic state, leading to both superficial and invasive infections. Although systemic candidiasis poses a life-threatening risk, a limited number of antifungal drugs are employed for its treatment.

View Article and Find Full Text PDF

Introduction: Apical periodontitis, mainly caused by bacterial infection in the dental pulp, is often accompanied by abscess, periapical inflammation, and alveolar bone loss. Lancefieldella rimae has been detected in the root canals of patients with apical periodontitis. Here, we investigated whether L.

View Article and Find Full Text PDF

Enterococcus faecalis is a Gram-positive bacterium that is frequently found in the periapical lesion of patients with apical periodontitis. Its biofilm formation in root canal is closely related to the development of refractory apical periodontitis by providing increased resistance to endodontic treatments. Phage therapy has recently been considered as an efficient therapeutic strategy in controlling various periodontal pathogens.

View Article and Find Full Text PDF

Human intestinal epithelial cells (IECs) play an important role in maintaining gut homeostasis by producing antimicrobial peptides (AMPs). Bacillus subtilis, a commensal bacterium, is considered a probiotic. Although its protective effects on intestinal health are widely reported, the key component of B.

View Article and Find Full Text PDF

Scrub typhus, a mite-borne infectious disease, is caused by . Despite many attempts to develop a protective strategy, an effective preventive vaccine has not been developed. The identification of appropriate Ags that cover diverse antigenic strains and provide long-lasting immunity is a fundamental challenge in the development of a scrub typhus vaccine.

View Article and Find Full Text PDF

Dendritic cells (DCs) play an important role in immunity by sensing and responding to invasive microbes. Bacillus species are rod-shaped sporulating bacteria that include the pathogenic Bacillus cereus and commensal Bacillus subtilis. Although the interaction between DC and these two Bacillus species has been studied, their key structural component that prompts DC activation is poorly understood.

View Article and Find Full Text PDF

Introduction: Preterm birth is a leading cause of infant mortality and morbidity. Despite the improvement in the overall mortality in premature infants, the intact survival of these infants remains a significant challenge. Screening the physical growth of infants is fundamental to potentially reducing the escalation of this disorder.

View Article and Find Full Text PDF

(pneumococcus) is an opportunistic pathogen that can cause severe infectious diseases such as pneumonia, meningitis, and otitis media. Despite the availability of antibiotics and pneumococcal vaccines against some invasive serotypes, pneumococcal infection remains a tremendous clinical challenge due to the increasing frequency of infection by antimicrobial resistant, nonencapsulated, and/or non-vaccine serotype strains. Short-chain fatty acids (SCFAs), which are produced at various mucosal sites in the body, have potent antimicrobial activity, including inhibition of pathogen growth and/or bacterial biofilm formation.

View Article and Find Full Text PDF

Bone resorption can be caused by excessive differentiation and/or activation of bone-resorbing osteoclasts. While microbe-associated molecular patterns can influence the differentiation and activation of bone cells, little is known about the role of lipoteichoic acid (LTA), a major cell wall component of Gram-positive bacteria, in the regulation of bone metabolism. In this study, we investigated the effect of LTA on bone metabolism using wild-type Staphylococcus aureus and the LTA-deficient mutant strain.

View Article and Find Full Text PDF

Introduction: Depression is a prevalent disorder worldwide, with potentially severe implications. It contributes significantly to an increased risk of diseases associated with multiple risk factors. Early accurate diagnosis of depressive symptoms is a critical first step toward management, intervention, and prevention.

View Article and Find Full Text PDF

Recently, several probiotic products have been developed; however, most probiotic applications focused on prokaryotic bacteria whereas eukaryotic probiotics have received little attention. Saccharomyces cerevisiae yeast strains are eukaryotes notable for their fermentation and functional food applications. The present study investigated the novel yeast strains isolated from Korean fermented beverages and examined their potential probiotic characteristics.

View Article and Find Full Text PDF

Dental caries or trauma can expose human dental pulp cells (DPCs) to various oral microorganisms, which play an important role in the development of an innate immune response. In the present study, we examined the expression of Toll-like receptors (TLRs) for sensing microbe-associated molecular patterns in human DPCs. Interestingly, real-time PCR analysis demonstrated that TLR3 is the most highly expressed among 10 different TLRs in human DPCs.

View Article and Find Full Text PDF

, an opportunistic Gram-positive bacterium, causes an infective endocarditis that could be fatal to human health. Dendritic cells (DCs) are known to be involved in disease progression and immune responses in infection. Since lipoteichoic acid (LTA) is a representative virulence factor of , we here investigated its role in the activation of human DCs stimulated with LTA-deficient (Δ) or LTA.

View Article and Find Full Text PDF

Enterococcus faecalis, a Gram-positive opportunistic pathogen having lipoteichoic acid (LTA) as a major virulence factor, is closely associated with refractory apical periodontitis. Short-chain fatty acids (SCFAs) are found in the apical lesion and may affect inflammatory responses induced by E. faecalis.

View Article and Find Full Text PDF

Numerous studies have aimed to develop novel advanced vaccines, in part because traditional vaccines have been unsuccessful in preventing rapidly emerging and reemerging viral and bacterial infections. There is a need for an advanced vaccine delivery system to ensure the successful induction of humoral and cellular immune responses. In particular, the ability of nanovaccines to modulate intracellular antigen delivery by inducing exogenous antigens (loaded onto major histocompatibility complex class 1 molecules) in CD8 T cells, the so-called cross-presentation pathway, has attracted a great deal of attention.

View Article and Find Full Text PDF

Wnt signaling is a positive regulator of bone formation through the induction of osteoblast differentiation and down-regulation of osteoclast differentiation. We previously reported that muramyl dipeptide (MDP) increases bone volume by increasing osteoblast activity and attenuating osteoclast activity in receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoporotic model mice. In this study, we investigated whether MDP could alleviate post-menopausal osteoporosis through Wnt signaling regulation in an ovariectomy (OVX)-induced mouse osteoporosis model.

View Article and Find Full Text PDF

Tissue damage caused by various stimuli under certain conditions, such as biological and environmental cues, can actively induce systemic and/or local immune responses. Therefore, understanding the immunological perspective would be critical to not only regulating homeostasis of organs and tissues but also to restrict and remodel their damage. Lungs serve as one of the key immunological organs, and thus, in the present article, we focus on the innate and adaptive immune systems involved in remodeling and engineering lung tissue.

View Article and Find Full Text PDF

is a pathogen that causes a variety of infectious diseases such as pneumonia, endocarditis, and septic shock. Methicillin-resistant (MRSA) evades virtually all available treatments, creating the need for an alternative control strategy. Although we previously demonstrated the inhibitory effect of sodium propionate (NaP) on MRSA, the regulatory mechanism of this effect remains unclear.

View Article and Find Full Text PDF
Article Synopsis
  • Cholera is a significant global health issue, and oral cholera vaccines (OCVs) are a key prevention strategy, with research suggesting the need to enhance their effectiveness against various cholera antigens beyond just O-antigen.
  • Patients recovering from cholera develop specific antibody responses that are crucial for immunity, highlighting the importance of targeting antigens like TCP and CT in OCV development.
  • Recent studies indicate that strains expressing the -139F allele can stimulate strong antibody responses in mice, making them promising candidates for improved inactivated OCVs that could lead to better protection against cholera.
View Article and Find Full Text PDF