What are Siglec receptors?

The sialic acid-binding immunoglobulin-type of lectins (Siglecs) are receptors that recognize sialic acid-containing glycans. In the majority of the cases, Siglecs are expressed on immune cells and play a critical role in regulating immune cell signaling.

Does surface sialic acid promote innate immunity?

Taken together, we have demonstrated that pathogens adsorb sialic acids from the host serum and use these to inhibit C3-deposition28. Additionally, these also promote association with the innate immune cells through siglec-dependent recognition to persist within the host.

How many human Siglecs are there?

In humans, there are nine CD33-related Siglecs and one Siglec-like protein, whereas in mice there are five CD33-related Siglecs.

What is sialic acid used for?

Sialic acids (Sias) are nine-carbon atoms sugars usually present as terminal residues of glycoproteins and glycolipids on the cell surface or secreted. They have important roles in cellular communication and also in infection and survival of pathogens.

Are macrophages CD11c+?

These cells are characterized by the expression of CD64 and MHCII and intermediate levels of F4/80, CD24, and CD11c (Figure 1c–e and Supplementary Figure S1a). At steady state, MHCII+ monocytes and macrophages express the mannose receptor (CD206), a marker associated with anti-inflammatory macrophage function.

What is sialic acid receptor?

Abstract. Sialic acid linked to glycoproteins and gangliosides is used by many viruses as a receptor for cell entry. These viruses include important human and animal pathogens, such as influenza, parainfluenza, mumps, corona, noro, rota, and DNA tumor viruses.

What is sialic acid How does it function in immunity?

Sialic acids can modulate the immune system in diverse ways through Siglecs, influence on antibody mediated clearance of pathogens and through complement. Sialylation of the antibody immunoglobulin A (IgA) interferes with the cell surface attachment of influenza A and mediates anti-viral activity of IgA (40).

Is sialic acid good?

Sialic Acid can effectively promote the development and functional repair of nerve cells, epithelial cells and immune cells, which can get the effect of improving immunity, promoting intellectual development , nourishing skin and anti-aging.

Which cells express sialic acid?

This is the major type of sialic acid present on human respiratory epithelial cells. Alpha(2,3) linked sialic acids are found on ciliated epithelial cells, which are a minor population within the human respiratory tract, and also on some epithelial cells in the lower tract.

Is sialic acid bad for you?

Neu5Gc, a non-human sialic acid sugar molecule common in red meat that increases the risk of tumor formation in humans, is also prevalent in pig organs, with concentrations increasing as the organs are cooked, a study by researchers from the UC Davis School of Medicine and Xiamen University School of Medicine has found …

How do Siglec cells recognize sialic acid?

As Siglecs recognize sialic acid-containing glycans that are expressed on all mammalian cells, they can help immune cells to discriminate between self and non-self. Sialylated pathogens can both subvert and promote immune responses through Siglec-dependent interactions.

Do Siglec ligands remodel in the germinal centre?

It is also notable that dramatic remodelling of the Siglec ligands expressed by B cells occurs in the germinal centre in both mice 91 and humans 93, yet the functional consequence of this remodelling remains largely unexplored.

What is the function of Siglecs?

Siglecs are a family sialic acid-binding immunoglobulin-like co-receptors that are expressed on most cells of the innate and adaptive immune systems. As Siglecs recognize sialic acid-containing glycans that are expressed on all mammalian cells, they can help immune cells to discriminate between self and non-self.

Can Siglec-7 ligands protect cancer cells from NK cell killer?

Indeed, as revealed by two recent studies 111, 112, the expression levels of Siglec-7 and Siglec-9 ligands are greatly increased on a variety of cancer cells, which decreases their susceptibility to NK cell killing.