Lactosylceramide-enriched microdomains mediate human neutrophil immunological functions via carbohydrate-carbohydrate interaction

Mosevoll

et al. 2023

Cells

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Common causes include gram-negative and gram-positive bacteria as well as fungi. Neutrophils are among the first cells to arrive at an infection site where they function as important effector cells of the innate immune system and as regulators of the host immune response. The regulation of neutrophil migration is therefore important both for the infection-directed host response and for the development of organ dysfunctions in sepsis. Downregulation of CXCR4/CXCL12 stimulates neutrophil migration from the bone marrow. This is followed by transmigration/extravasation across the endothelial cell barrier at the infection site; this process is directed by adhesion molecules and various chemotactic gradients created by chemotactic cytokines, lipid mediators, bacterial peptides, and peptides from damaged cells. These mechanisms of neutrophil migration are modulated by sepsis, leading to reduced neutrophil migration and even reversed migration that contributes to distant organ failure. The sepsis-induced modulation seems to differ between neutrophil subsets. Furthermore, sepsis patients should be regarded as heterogeneous because neutrophil migration will possibly be further modulated by the infecting microorganisms, antimicrobial treatment, patient age/frailty/sex, other diseases (e.g., hematological malignancies and stem cell transplantation), and the metabolic status. The present review describes molecular mechanisms involved in the regulation of neutrophil migration; how these mechanisms are altered during sepsis; and how bacteria/fungi, antimicrobial treatment, and aging/frailty/comorbidity influence the regulation of neutrophil migration.

Section: Important Bacterial Products That Interfere With Neutrophil ...mentioning

confidence: 99%

Section: Important Bacterial Products That Interfere With Neutrophil ...mentioning

confidence: 99%

The Regulation of Neutrophil Migration in Patients with Sepsis: The Complexity of the Molecular Mechanisms and Their Modulation in Sepsis and the Heterogeneity of Sepsis Patients

Mosevoll

et al. 2023

Cells

“…Subsequent studies highlighted that GM1–TrkA interaction modulates TrkA autophosphorylation, and the presence of NGF is also required for proper complex formation: if NGF is missing, GM1 has no effect on TrkA signalling (Fig. 2A) [16]. Vice versa, NGF requires membrane GM1 associated with TrkA in order to properly activate the receptor [52].…”

Section: Lipid‐raft Dynamicsmentioning

confidence: 99%

“…Examples of this are the interaction between tubulin and GM1 in neuronal cells [14] and the association between GM1 and caveolin in A431 or Madin‐Darby canine kidney (MDCK) cells [15], both of which depend on direct binding within the same membrane domain. A similar example is provided by the interaction between lactosylceramide and tyrosine‐protein kinase Lyn in the plasma membrane of neutrophils [16], although it involves a neutral glycosphingolipid. In the next section, we give insights into ganglioside–receptor interactions in lipid rafts and their impact on signal transduction in physiopathological states.…”

mentioning

confidence: 99%

Regulation of signal transduction by gangliosides in lipid rafts: focus on GM3–IR and GM1–TrkA interactions

et al. 2022

The interactions between gangliosides and proteins belonging to the same or different lipid domains and their influence on physiological and pathological states have been analysed in detail. A well-known factor impacting on lipidprotein interactions and their biological outcomes is the dynamic composition of plasma membrane. This review focuses on GM1 and GM3 gangliosides because they are an integral part of protein-receptor complexes and dysregulation of their concentration shows a direct correlation with the onset of pathological conditions. We first discuss the interaction between GM3 and insulin receptor in relation to insulin responses, with an increase in GM3 correlating with the onset of metabolic dysfunction. Next, we describe the case of the GM1-TrkA interaction, relevant to nerve-cell differentiation and homeostasis as deficiency in plasma-membrane GM1 is known to promote neurodegeneration. These two examples highlight the fact that interactions between gangliosides and receptor proteins within the plasma membrane are crucial in controlling cell signalling and pathophysiological cellular states.

“…B4GALT5 was found to be modulated in several cancers, including colorectal [ 10 ], breast [ 11 ], and hepatocellular carcinoma [ 12 ], as well as in acute myeloid leukemia [ 13 ]. LacCer was also reported to be involved in diabetes [ 14 ], inflammatory bowel disease [ 15 ], adipocyte differentiation [ 6 , 16 ], and immunological functions of neutrophils [ 17 ]. Despite LacCer synthase’s pleiotropic relevance in both physiological and pathological conditions, a convenient enzymatic assay in vitro is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Convenient and Sensitive Measurement of Lactosylceramide Synthase Activity Using Deuterated Glucosylceramide and Mass Spectrometry

Dei

Montavoci

Casati

et al. 2023

IJMS

Lactosylceramide is necessary for the biosynthesis of almost all classes of glycosphingolipids and plays a relevant role in pathways involved in neuroinflammation. It is synthesized by the action of galactosyltransferases B4GALT5 and B4GALT6, which transfer galactose from UDP-galactose to glucosylceramide. Lactosylceramide synthase activity was classically determined in vitro by a method based on the incorporation of radiolabeled galactose followed by the chromatographic separation and quantitation of the product by liquid scintillation counting. Here, we used deuterated glucosylceramide as the acceptor substrate and quantitated the deuterated lactosylceramide product by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). We compared this method with the classical radiochemical method and found that the reactions have similar requirements and provide comparable results in the presence of high synthase activity. Conversely, when the biological source lacked lactosylceramide synthase activity, as in the case of a crude homogenate of human dermal fibroblasts, the radiochemical method failed, while the other provided a reliable measurement. In addition to being very accurate and sensitive, the proposed use of deuterated glucosylceramide and LC-MS/MS for the detection of lactosylceramide synthase in vitro has the relevant advantage of avoiding the costs and discomforts of managing radiochemicals.