Immunopathogenesis of Different Emerging Viral Infections: Evasion, Fatal Mechanism, and Prevention.

Different emerging viral infections may emerge in different regions of the world and pose a global pandemic threat with high fatality. Clarification of the immunopathogenesis of different emerging viral infections can provide a plan for the crisis management and prevention of emerging infections. This perspective article describes how an emerging viral infection evolves from microbial mutation, zoonotic and/or vector-borne transmission that progresses to a fatal infection due to overt viremia, tissue-specific cytotropic damage or/and immunopathology. We classified immunopathogenesis of common emerging viral infections into 4 categories: 1) deficient immunity with disseminated viremia (e.g., Ebola); 2) pneumocytotropism with/without later hyperinflammation (e.g., COVID-19); 3) augmented immunopathology (e.g., Hanta); and 4) antibody-dependent enhancement of infection with altered immunity (e.g., Dengue). A practical guide to early blocking of viral evasion, limiting viral load and identifying the fatal mechanism of an emerging viral infection is provided to prevent and reduce the transmission, and to do rapid diagnoses followed by the early treatment of virus neutralization for reduction of morbidity and mortality of an emerging viral infection such as COVID-19.

Variation in fracture risk estimation among East Asian women.

OBJECTIVES: Bone mineral density (BMD) testing and fracture risk calculation help clinicians assess fracture risk and counsel patients. However, predicted fracture risks and outcomes for US East Asian individuals remain understudied. STUDY DESIGN: Retrospective cohort study. METHODS: Using standardized clinical profiles for East Asian women aged 70 years, fracture probabilities were estimated using the US Fracture Risk Assessment Tool (FRAX) version 4.1 and corresponding FRAX tools for East Asian countries. Next, clinical and BMD data from 3785 US Asian women aged 65 to 74 years were used to estimate 10-year hip fracture risk (US-Asian FRAX-v3.1) in comparison with actual observed 10-year hip fracture risk (Kaplan-Meier product limit estimate). RESULTS: For the same patient profile entered in the US-Asian FRAX and country-specific FRAX, the calculated 10-year hip fracture probability varied. Compared with the US-Asian FRAX calculator, the estimate was 2-fold higher using the Taiwan FRAX and Hong Kong FRAX, somewhat higher using the South Korea FRAX and Japan FRAX, and similar using the China FRAX. Among 3785 US Asian women (mean [SD] age, 69 [3] years), 23 experienced a hip fracture during a median follow-up of 6.8 years. Their observed 10-year hip fracture risk was 1.5% (95% CI, 0.8%-2.7%), and their median (interquartile range) predicted fracture probability (US-Asian FRAX-v3.1) was 1.1% (0.6%-2.0%). CONCLUSIONS: Country-specific FRAX estimates varied between the United States and East Asian countries. For US Asian women, the US FRAX-predicted hip fracture probabilities were in the lower range of observed risk. Although these findings support the use of the US-Asian FRAX for hip fracture risk assessment in US East Asian women, further studies are needed, including the examination of Asian subgroups.

Embryonic cardiac chamber maturation: Trabeculation, conduction, and cardiomyocyte proliferation.

Congenital heart diseases are some of the most common human birth defects. Though some congenital heart defects can be surgically corrected, treatment options for other congenital heart diseases are very limited. In many congenital heart diseases, genetic defects lead to impaired embryonic heart development or growth. One of the key development processes in cardiac development is chamber maturation, and alterations in this maturation process can manifest as a variety of congenital defects including non-compaction, systolic dysfunction, diastolic dysfunction, and arrhythmia. During development, to meet the increasing metabolic demands of the developing embryo, the myocardial wall undergoes extensive remodeling characterized by the formation of muscular luminal protrusions called cardiac trabeculae, increased cardiomyocyte mass, and development of the ventricular conduction system. Though the basic morphological and cytological changes involved in early heart development are clear, much remains unknown about the complex biomolecular mechanisms governing chamber maturation. In this review, we highlight evidence suggesting that a wide variety of basic signaling pathways and biomechanical forces are involved in cardiac wall maturation.

Sialylated glycans as receptor and inhibitor of enterovirus 71 infection to DLD-1 intestinal cells.

BACKGROUND: Many viruses recognize specific sugar residues, particularly sulfated or sialylated glycans, as the infection receptors. A change of sialic acid (2-6)-linked galactose (SA-alpha2,6Gal) to SA-alpha2,3Gal determines the receptor for avian flu infection. The receptor for enterovirus 71 (EV71) infection that frequently causes fatal encephalitis in Asian children remains unclear. Currently, there is no effective vaccine or anti-virus agent for EV71 infection. Using DLD-1 intestinal cells, this study investigated whether SA-linked glycan on DLD-1 intestinal cells was a receptor for EV71, and whether natural SA-linked sugars from human milk could block EV71 infection. RESULTS: EV71 specifically infected DLD-1 intestinal cells but not K562 myeloid cells. Depletion of O-linked glycans or glycolipids, but not N-linked glycans, significantly decreased EV71 infection of DLD-1 cells. Pretreatment of DLD-1 cells with sialidase (10 mU, 2 hours) significantly reduced 20-fold EV71 replication (p < 0.01). Taken together, these results suggest that SA-linked O-glycans and glycolipids, but not N-glycans, on DLD-1 cells were responsible for EV71 infection. Purified SA-alpha2,3Gal and SA-alpha2,6Gal from human milk significantly inhibited EV71 infection of DLD-1 cells, indicating terminal SA-linked glycans could be receptors and inhibitors of EV71 infection. CONCLUSION: This is the first in the literature to demonstrate that EV71 uses SA-linked glycans as receptors for infection, and natural SA-linked glycans from human milk can protect intestinal cells from EV71 infection. Further studies will test how a SA-containing glycan can prevent EV71 in the future.