Lipoteichoic acid (LTA) is a major constituent of the cell wall of

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

bacteria. These organisms have an inner (or cytoplasmic) membrane and, external to it, a thick (up to 80 nanometer) peptidoglycan layer. The structure of LTA varies between the different species of Gram-positive bacteria and may contain long chains of

ribitol Ribitol, or adonitol, is a crystalline pentose alcohol (C5H12O5) formed by the reduction of ribose. It occurs naturally in the plant '' Adonis vernalis'' as well as in the cell walls of some Gram-positive bacteria, in the form of ribitol phosp ...

glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...

phosphate. LTA is anchored to the cell membrane via a

diacylglycerol A diglyceride, or diacylglycerol (DAG), is a glyceride consisting of two fatty acid chains covalently bonded to a glycerol molecule through ester linkages. Two possible forms exist, 1,2-diacylglycerols and 1,3-diacylglycerols. DAGs can act as s ...

. It acts as regulator of autolytic wall enzymes ( muramidases). It has antigenic properties being able to stimulate specific immune response.Lipoteichoic acid's chemical signals is C28H74O37P3=OH.

LTA may bind to target cells non-specifically through membrane

phospholipids Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids t ...

, or specifically to

CD14 CD14 (cluster of differentiation 14) is a human protein made mostly by macrophages as part of the innate immune system. It helps to detect bacteria in the body by binding lipopolysaccharide (LPS), a pathogen-associated molecular pattern (PAMP). ...

and to Toll-like receptors. Binding to TLR-2 has shown to induce

NF-κB Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a protein complex that controls transcription of DNA, cytokine production and cell survival. NF-κB is found in almost all animal cell types and is involved in cellular ...

expression(a central

transcription factor In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The f ...

), elevating expression of both pro- and anti-

apoptotic Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes ( morphology) and death. These changes incl ...

genes. Its activation also induces mitogen-activated protein kinases (MAPK) activation along with phosphoinositide 3-kinase activation.

Studies

LTA's molecular structure has been found to have the strongest hydrophobic bonds of an entire bacteria. Said et al. showed that LTA causes an IL-10-dependent inhibition of CD4 T-cell expansion and function by up-regulating PD-1 levels on monocytes which leads to IL-10 production by monocytes after binding of PD-1 by PD-L.Elias A. Said et al. 2009, PD-1 Induced IL10 Production by Monocytes Impairs T-cell Activation in a Reversible Fashion. Nature Medicine. 2010; 452-9. Lipoteichoic acid (LTA) from Gram-positive bacteria exerts different immune effects depending on the bacterial source from which it is isolated. For example, LTA from ''Enterococcus faecalis'' is a virulence factor positively correlating to inflammatory damage to teeth during acute infection. On the other hand, a study reported '' Lacticaseibacillus rhamnosus'' GG LTA (LGG-LTA) oral administration reduce
immunosuppression and skin tumor development in mice
In animal studies, specific bacterial LTA has been correlated with induction of arthritis, nephritis, uveitis, encephalomyelitis, meningeal inflammation, and periodontal lesions, and also triggered cascades resulting in septic shock and multiorgan failure.

References

*Department of Oral Biology, Hebrew University-Hadassah Faculty of Dental Medicine, Ein-Kerem Campus, Jerusalem, Israel.

External links

* {{Bacteria Organic acids Cell biology