Galectin-3 and Its Genetic Variation rs4644 Modulate Enterovirus 71 Infection

The Pivotal Role of Galectin-3 in Viral Infection: A Multifaceted Player in Host-Pathogen Interactions

Galectin-3 (Gal-3), a beta-galactoside-binding lectin, plays a pivotal role in various cellular processes, including immune responses, inflammation, and cancer progression. This comprehensive review aims to elucidate the multifaceted functions of Gal-3, starting with its crucial involvement in viral entry through facilitating viral attachment and catalyzing internalization. Furthermore, Gal-3 assumes significant roles in modulating immune responses, encompassing the activation and recruitment of immune cells, regulation of immune signaling pathways, and orchestration of cellular processes such as apoptosis and autophagy. The impact of Gal-3 extends to the viral life cycle, encompassing critical phases such as replication, assembly, and release. Notably, Gal-3 also contributes to viral pathogenesis, demonstrating involvement in tissue damage, inflammation, and viral persistence and latency elements. A detailed examination of specific viral diseases, including SARS-CoV-2, HIV, and influenza A, underscores the intricate role of Gal-3 in modulating immune responses and facilitating viral adherence and entry. Moreover, the potential of Gal-3 as a biomarker for disease severity, particularly in COVID-19, is considered. Gaining further insight into the mechanisms and roles of Gal-3 in these infections could pave the way for the development of innovative treatment and prevention options for a wide range of viral diseases.

Diagnostic Significance of Serum Galectin-3 in Hospitalized Patients with COVID-19-A Preliminary Study

Severe coronavirus disease 2019 (COVID-19) is associated with hyperinflammation leading to organ injury, including respiratory failure. Galectin-3 was implicated in innate immunological response to infections and in chronic fibrosis. The aim of our preliminary study was the assessment of the diagnostic utility of serum galectin-3 in patients with COVID-19. The prospective observational study included adult patients admitted with active COVID-19 and treated in tertiary hospital between June and July 2020. The diagnosis was confirmed by the quantitative detection of nucleic acid of severe acute respiratory syndrome coronavirus 2 in nasopharyngeal swabs. Galectin-3 was measured by enzyme immunoassay in serum samples obtained during the first five days of hospital stay. We included 70 patients aged 25 to 73 years; 90% had at least one comorbidity. During the hospital stay, 32.9% were diagnosed with COVID-19 pneumonia and 12.9% required treatment in the intensive care unit (ICU). Serum galectin-3 was significantly increased in patients who developed pneumonia, particularly those who required ICU admission. Positive correlations were found between galectin-3 and inflammatory markers (interleukin-6, C-reactive protein, ferritin, pentraxin-3), a marker of endothelial injury (soluble fms-like tyrosine kinase-1), and a range of tissue injury markers. Serum galectin-3 enabled the diagnosis of pneumonia with moderate diagnostic accuracy and the need for ICU treatment with high diagnostic accuracy. Our findings strengthen the hypothesis that galectin-3 may be involved in severe COVID-19. Further studies are planned to confirm the preliminary results and to verify possible associations of galectin-3 with long-term consequences of COVID-19, including pulmonary fibrosis.

The role of galectins in virus infection - A systemic literature review

BACKGROUND

Galectins are β-Galactose binding lectins expressed in numerous cells and play multiple roles in various physiological and cellular functions. However, few information is available regarding the role of galectins in virus infections. Here, we conducted a systemic literature review to analyze the role of galectins in human virus infection.

METHODS

This study uses a systematic method to identify and select eligible articles according to the PRISMA guidelines. References were selected from PubMed, Web of Science and Google Scholar database covering publication dated from August 1995 to December 2018.

RESULTS

Results indicate that galectins play multiple roles in regulation of virus infections. Galectin-1 (Gal-1), galectin-3 (Gal-3), galectin-8 (Gal-8), and galectin-9 (Gal-9) were found as the most predominant galectins reported to participate in virus infection. The regulatory function of galectins occurs by extracellularly binding to viral glycosylated envelope proteins, interacting with ligands or receptors on immune cells, or acting intracellularly with viral or cellular components in the cytoplasm. Several galectins express either positive or negative regulatory role, while some had dual regulatory capabilities on virus propagation based on the conditions and their localization. However, limited information about the endogenous function of galectins were found. Therefore, the endogenous effects of galectins in host-virus regulation remains valuable to investigate.

CONCLUSIONS

This study offers information regarding the various roles galectins shown in viral infection and suggest that galectins can potentially be used as viral therapeutic targets or antagonists.

Utilization of Galectins by Pathogens for Infection

Galectins are glycan-binding proteins which are expressed by many different cell types and secreted extracellularly. These molecules are well-known regulators of immune responses and involved in a broad range of cellular and pathophysiological functions. During infections, host galectins can either avoid or facilitate infections by interacting with host cells- and/or pathogen-derived glycoconjugates and less commonly, with proteins. Some pathogens also express self-produced galectins to interfere with host immune responses. This review summarizes pathogens which take advantage of host- or pathogen-produced galectins to establish the infection.

Galectins in Host-Pathogen Interactions: Structural, Functional and Evolutionary Aspects

Galectins are a family of ß-galactoside-binding lectins characterized by a unique sequence motif in the carbohydrate recognition domain, and evolutionary and structural conservation from fungi to invertebrates and vertebrates, including mammals. Their biological roles, initially understood as limited to recognition of endogenous ("self") carbohydrate ligands in embryogenesis and early development, dramatically expanded in later years by the discovery of their roles in tissue repair, cancer, adipogenesis, and regulation of immune homeostasis. In recent years, however, evidence has also accumulated to support the notion that galectins can bind ("non-self") glycans on the surface of potentially pathogenic microbes, and function as recognition and effector factors in innate immunity. Thus, this evidence has established a new paradigm by which galectins can function not only as pattern recognition receptors but also as effector factors, by binding to the microbial surface and inhibiting adhesion and/or entry into the host cell, directly killing the potential pathogen by disrupting its surface structures, or by promoting phagocytosis, encapsulation, autophagy, and pathogen clearance from circulation. Strikingly, some viruses, bacteria, and protistan parasites take advantage of the aforementioned recognition roles of the vector/host galectins, for successful attachment and invasion. These recent findings suggest that galectin-mediated innate immune recognition and effector mechanisms, which throughout evolution have remained effective for preventing or fighting viral, bacterial, and parasitic infection, have been "subverted" by certain pathogens by unique evolutionary adaptations of their surface glycome to gain host entry, and the acquisition of effective mechanisms to evade the host's immune responses.

Gal power: the diverse roles of galectins in regulating viral infections

Viruses, as a class of pathogenic microbe, remain a significant health burden globally. Viral infections result in significant morbidity and mortality annually and many remain in need of novel vaccine and anti-viral strategies. The development of effective novel anti-viral therapeutics, in particular, requires detailed understanding of the mechanism of viral infection, and the host response, including the innate and adaptive arms of the immune system. In recent years, the role of glycans and lectins in pathogen-host interactions has become an increasingly relevant issue. This review focuses on the interactions between a specific lectin family, galectins, and the broad range of viral infections in which they play a role. Discussed are the diverse activities that galectins play in interacting directly with virions or the cells they infect, to promote or inhibit viral infection. In addition we describe how galectin expression is regulated both transcriptionally and post-transcriptionally by viral infections. We also compare the contribution of known galectin-mediated immune modulation, across a range of innate and adaptive immune anti-viral responses, to the outcome of viral infections.