Suppression of human T cell activation by derivatives of glycerol monolaurate

Glycerides of lauric acid supplementation in the chicken diet enhances the humoral and cellular immune response to infectious bronchitis virus

Controlling pathogenic infections while reducing antibiotic usage is an important challenge during poultry production. In addition to vaccination strategies, several solutions to enhance the immune response against pathogens are evaluated. In this study, we aim to determine the effects of the glycerides of lauric acid (GLA) supplementation in chickens' diets on humoral and cellular immune response pathogenic infections, using an in vivo model of infectious bronchitis virus (IBV). One-day-old Ross 308 broilers were vaccinated with live attenuated IBV and fed diets supplemented with or without GLA at 3 kg/ton. The levels of early (day 7) specific anti-IBV in sera were significantly increased in broilers fed GLA, compared to the control groups (P<0.05), showing a stronger primary humoral response. The secretion levels of main cytokines remained similar in spleens of all the experimental groups. However, the splenocytes from broilers fed GLA showed higher activation and effector abilities when measured by IFN-γ ELISpot in presence of N-261-280 IBV peptide or Concanavalin A (Con A), a pan T lymphocytes mitogen. In response to N-261-280 peptide, GLA group showed a 2-fold increase of spot numbers (P < 0.05) and 3-fold increase of spot surfaces (P < 0.01) compared to the control groups. Similarly, Con A stimulation showed a 2-fold increases in spot surfaces and numbers in the GLA supplemented group compared to the control group (P < 0.01). In summary, GLA supplementation in chicken feed enhances the primary humoral immune response and strengthen the T lymphocytes mediated cellular immune response. These findings demonstrate how GLA can improve chicken resilience against pathogenic challenges by enhancing their immune responses.

Glycerol monolaurate improves intestinal morphology and antioxidant status by suppressing inflammatory responses and nuclear factor kappa-B signaling in lipopolysaccharide-exposed chicken embryos

Medium-chain fatty acids and their derivatives are natural ingredients that support immunological functions in animals. The effects of glycerol monolaurate (GML) on intestinal innate immunity and associated molecular mechanisms were investigated using a chicken embryo model. Sixty-four Arbor Acres broiler embryos were randomly allocated into four groups. On embryonic day 17.5, the broiler embryos were administered with 9 mg of GML, which was followed by a 12-h incubation period and a 12-h challenge with 32 μg of lipopolysaccharide (LPS). On embryonic day 18.5, the jejunum and ileum were harvested. Results indicated that GML reversed the LPS-induced decline in villus height and upregulated the expression of mucin 2 (P < 0.05). GML decreased LPS-induced malondialdehyde production and boosted antioxidant enzyme activity (P < 0.05). GML alleviated LPS-stimulated intestinal secretion of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) (P < 0.05). GML also normalized LPS-induced changes in the gene expression of Toll-like receptor 4, nuclear factor kappa-B p65 (NF-κB p65), cyclooxygenase-2, NOD-like receptor protein 3, IL-18, zonula occludens 1, and occludin (P < 0.05). GML enhanced as well the expression of AMP-activated protein kinase α1 and claudin 1 (P < 0.05). In conclusion, GML improved intestinal morphology and antioxidant status by alleviating inflammatory responses and modulating NF-κB signaling in LPS-challenged broiler embryos.

Glycerol monolaurate inhibits Francisella novicida growth and is produced intracellularly in an ISG15-dependent manner

Glycerol Monolaurate (GML) is a naturally occurring fatty acid monoester with antimicrobial properties. Francisella tularensis is an agent of bioterrorism known for its unique lipopolysaccharide structure and low immunogenicity. Here we assessed whether exogenous GML would inhibit the growth of Francisella novicida . GML potently impeded Francisella growth and survival in vitro . To appraise the metabolic response to infection, we used GC-MS to survey the metabolome, and surprisingly, observed intracellular GML production following Francisella infection. Notably, the ubiquitin-like protein ISG15 was necessary for increased GML levels induced by bacterial infection, and enhanced ISG15 conjugation correlated with GML levels following serum starvation.

Supplementation with alpha-glycerol monolaurate during late gestation and lactation enhances sow performance, ameliorates milk composition, and improves growth of suckling piglets

BACKGROUND

Physiological changes during lactation cause oxidative stress in sows, reduce immunity, and hamper the growth capacity of piglets. Alpha-glycerol monolaurate (α-GML) has potential for enhancing the antimicrobial activity of sows and the growth of suckling piglets.

METHODS

Eighty sows were allocated randomly to four groups: basal diet and basal diets supplemented with 500, 1000, or 2000 mg/kg α-GML. The experiment started on d 85 of gestation and lasted until piglets were weaned on d 21 of lactation. The number of live-born piglets was standardized to 12 ± 1 per sow on day of parturition. On d 0 and 21 of lactation, body weight of piglets was measured and milk samples were obtained from sows, and serum samples and feces from piglets were obtained on d 21.

RESULTS

Feed intake, backfat loss, and weaning estrus interval did not differ among the four groups of sows. Maternal α-GML supplementation increased (P < 0.05) the body weight of piglets at weaning and the apparent total tract digestibility of crude fat of sows. The immunoglobulin A and immunoglobulin G levels were greater (P < 0.05) in a quadratic manner in the milk of sows as dietary α-GML increased. Concerning fatty acid profile, C12:0, C15:0, C17:0, C18:2n6c, C18:3n3, C24:0, and C22:6n3 were higher (P < 0.05) in linear and quadratic manners in colostrum of sows-fed α-GML diets compared with the control sows. There was lower (P < 0.05) n-6:n-3 polyunsaturated fatty acid ratio in milk than in the control sows. Maternal α-GML increased the abundance of Firmicutes (P < 0.05) and decreased the abundance of Proteobacteria (P < 0.05) of piglet fecal microbiota.

CONCLUSIONS

Dietary supplementation with α-GML improved milk immunoglobulins and altered fatty acids of sows, thereby improving the health of piglets.

In vitro and in vivo antiviral activity of monolaurin against Seneca Valley virus

Introduction

Surveillance of the Seneca Valley virus (SVV) shows a disproportionately higher incidence on Chinese pig farms. Currently, there are no vaccines or drugs to treat SVV infection effectively and effective treatment options are urgently needed.

Methods

In this study, we evaluated the antiviral activity of the following medium-chain fatty acids (MCFAs) or triglycerides (MCTs) against SVV: caprylic acid, caprylic monoglyceride, capric monoglyceride, and monolaurin.

Results

In vitro experiments showed that monolaurin inhibited viral replication by up to 80%, while in vivo studies showed that monolaurin reduced clinical manifestations, viral load, and organ damage in SVV-infected piglets. Monolaurin significantly reduced the release of inflammatory cytokines and promoted the release of interferon-γ, which enhanced the viral clearance activity of this type of MCFA.

Discussion

Therefore, monolaurin is a potentially effective candidate for the treatment of SVV infection in pigs.

Glycerol monolaurate ameliorates DSS-induced acute colitis by inhibiting infiltration of Th17, neutrophils, macrophages and altering the gut microbiota

Background and aims

Inflammatory bowel disease (IBD) places a heavy medical burden on countries and families due to repeated and prolonged attacks, and the incidence and prevalence of IBD are increasing worldwide. Therefore, finding an effective treatment is a matter of great urgency. Glycerol monolaurate (GML), which has a twelve-carbon chain, is a compound naturally found in human breast milk. Some studies have shown that GML has antibacterial and anti-inflammatory effects. However, the specific mechanism of action remains unclear.

Methods

Acute colitis was established in mice using 3% DSS, and glycerol monolaurate (500 mg·kg-¹) was administered for two weeks. QPCR and western blotting were performed to examine the inflammatory status. Mice described were subjected to flow cytometry analysis for immune cell activation.

Results

GML treated alleviated macroscopic symptoms such as shortened colons, increased spleen weight, and caused weight loss in mice with DSS-induced colitis. In addition, GML decreased the expression of pro-inflammatory factors (NF-α, IL-1β and IL-1α) and increased the expression of anti-inflammatory factors (IL-10 and TGF-β). GML inhibited the activation of the MAPK and NF-κB signalling pathways, improved tissue damage, and increased the expression of intestinal tight junction proteins. In addition, LPMCs extracted from intestinal tissue via flow cytometry showed that GML treatment led to a decrease of Th17 cells, Neutrophils and Macrophages. 16S rDNA sequencing showed that GML increased the abundance of commensal bacterium such as Akkermansia and Lactobacillus murinus.

Conclusions

We showed that oral administration of GML ameliorated DSS-induced colitis by inhibiting infiltration of Th17 cells, Neutrophils, and Macrophages, protecting the intestinal mucosal barrier and altered the abundance of commensal bacterium. This study provides new insights into the biological function and therapeutic potential of GML in the treatment of IBD.

Glycerol monolaurate inhibition of human B cell activation

Glycerol monolaurate (GML) is a naturally occurring antimicrobial agent used commercially in numerous products and food items. GML is also used as a homeopathic agent and is being clinically tested to treat several human diseases. In addition to its anti-microbial function, GML suppresses immune cell proliferation and inhibits primary human T cell activation. GML suppresses T cell activation by altering membrane dynamics and disrupting the formation of protein clusters necessary for intracellular signaling. The ability of GML to disrupt cellular membranes suggests it may alter other cell types. To explore this possibility, we tested how GML affects human B cells. We found that GML inhibits BCR-induced cytokine production, phosphorylation of signaling proteins, and protein clustering, while also changing cellular membrane dynamics and dysregulating cytoskeleton rearrangement. Although similar, there are also differences between how B cells and T cells respond to GML. These differences suggest that unique intrinsic features of a cell may result in differential responses to GML treatment. Overall, this study expands our understanding of how GML impacts the adaptive immune response and contributes to a broader knowledge of immune modulating monoglycerides.

Mechanistic Evaluation of Antimicrobial Lipid Interactions with Tethered Lipid Bilayers by Electrochemical Impedance Spectroscopy

There is extensive interest in developing real-time biosensing strategies to characterize the membrane-disruptive properties of antimicrobial lipids and surfactants. Currently used biosensing strategies mainly focus on tracking membrane morphological changes such as budding and tubule formation, while there is an outstanding need to develop a label-free biosensing strategy to directly evaluate the molecular-level mechanistic details by which antimicrobial lipids and surfactants disrupt lipid membranes. Herein, using electrochemical impedance spectroscopy (EIS), we conducted label-free biosensing measurements to track the real-time interactions between three representative compounds—glycerol monolaurate (GML), lauric acid (LA), and sodium dodecyl sulfate (SDS)—and a tethered bilayer lipid membrane (tBLM) platform. The EIS measurements verified that all three compounds are mainly active above their respective critical micelle concentration (CMC) values, while also revealing that GML induces irreversible membrane damage whereas the membrane-disruptive effects of LA are largely reversible. In addition, SDS micelles caused membrane solubilization, while SDS monomers still caused membrane defect formation, shedding light on how antimicrobial lipids and surfactants can be active in, not only micellar form, but also as monomers in some cases. These findings expand our mechanistic knowledge of how antimicrobial lipids and surfactants disrupt lipid membranes and demonstrate the analytical merits of utilizing the EIS sensing approach to comparatively evaluate membrane-disruptive antimicrobial compounds.