The LEAP2 response to cancer-related anorexia-cachexia syndrome in male mice and patients.

The hormone ghrelin serves a protective role in cancer-related anorexia-cachexia syndrome (CACS) - a condition in which plasma levels of ghrelin rise, its administration lessens CACS severity, and experimentally-reduced signaling by its receptor (GHSR) worsens fat loss and anorexia and accelerates death. Yet, actions for the related hormone liver-expressed antimicrobial peptide-2 (LEAP2), which is an endogenous GHSR antagonist, are unexplored in CACS. Here, we found that plasma LEAP2 and LEAP2/ghrelin ratio were lower in Lewis Lung Carcinoma (LLC) and RM-9 prostate cancer CACS mouse models. Ghrelin deletion exaggerated losses of tumor-free body weight and fat mass, reduced food intake, reduced soleus muscle weight, and/or lowered grip strength in LLC or RM-9 tumor-bearing mice. LEAP2 deletion lessened reductions in tumor-free body weight and fat mass and increased food intake in LLC or RM-9 tumor-bearing mice. In a 55-subject cohort of patients with CACS or weight-stable cancer, the plasma LEAP2/total ghrelin ratio was negatively correlated with 6-month weight change preceding blood collection. These data demonstrate that ghrelin deletion exacerbates CACS in the LLC and RM-9 tumor-bearing mouse models while contrastingly, LEAP2 deletion reduces measures of CACS in these tumor-bearing mouse models. Further, they suggest that lower plasma LEAP2/ghrelin ratio protects against worsened CACS.

The Concentration of Liver-Expressed Antimicrobial Peptide 2 in Human Milk and Infant Plasma Is Positively Associated with Adiposity and Body Weight in the First Year of Life.

BACKGROUND: The liver-expressed antimicrobial peptide 2 (LEAP2) is a recently recognized anorectic and glucose-regulating hormone with an unknown role in lactation. OBJECTIVES: The objectives of this study were as follows: 1) to assess LEAP2 presence in human milk and putative associations with infant body weight and adiposity in the first year of life, 2) to evaluate the impact of maternal weight status on LEAP2 concentration, and 3) to explore the relationship between infant plasma LEAP2 concentration and body weight and adiposity. METHODS: This prospective cohort observational study assessed LEAP2 concentration in plasma and milk from lactating women with normal weight (n = 26) or overweight or obesity (OW/OB, n = 26) at 6 mo postpartum and in 6-mo-old infant plasma, examining associations with metabolic and anthropometric variables at 6 mo and 1 y. Maternal plasma and milk leptin and insulin concentrations were also measured. LEAP2 expression in milk fat globules and single-cell-RNA-sequencing datasets was evaluated. RESULTS: LEAP2 was detected in all milk samples assessed (2.08 ± 0.65 ng/mL) and was positively associated with infant triceps (P = 0.022, Cohen f2 = 1.25) and subscapular (P = 0.008, f2 = 0.68) skinfolds at 1 y old. Maternal LEAP2 was positively associated with insulin (P = 0.005, f2 = 0.30) and prepregnancy body mass index (BMI) (P = 0.040, f2 = 0.17) and negatively associated with gestational weight gain (P = 0.008, f2 = 0.25) and postpartum weight retention (P = 0.036, f2 = 0.15). Maternal LEAP2 was higher in plasma (P = 0.039), but not milk of lactating women with OW/OB. Infant plasma LEAP2 (1.98 ± 0.28 ng/mL) was positively associated with weight (P = 0.004, f2 = 0.63), BMI (P = 0.049, f2 = 0.37), and weight-for-length (P = 0.024, f2 = 0.35) z-scores at 1 y old, predominantly in males. No evidence for LEAP2 mRNA expression was found in mammary cells. CONCLUSIONS: Milk LEAP2 is a bioactive component that plays a role in infant fat accretion in the first year of life. Although maternal LEAP2 responds to weight change in pregnancy and lactation, infant plasma LEAP2 might be involved in body weight regulation in early life. This trial was registered at clinicaltrials.gov as NCT05798676.

Deficiency of leap2 promotes somatic growth in zebrafish: Involvement of the growth hormone system.

Purpose: Liver-expressed antimicrobial peptide-2 (LEAP2) is identified as an endogenous antagonist and inverse agonist of the growth hormone secretagogue receptor type 1a (GHSR1a), its effect on the GHSR1a is contrary to the role of GHRELIN. Growth hormone (GH) is a crucial hormone for early development. Previous studies report that LEAP2 dose-dependently attenuates ghrelin-induced GH secretion, and Leap2-knockout mice exhibit increased plasma GH levels after GHRELIN administration. Clinical data revealed a possible correlation between LEAP2 and height development. However, the role of LEAP2 in early development remains unclear. This study aimed to investigate the role of LEAP2 in early development using leap2 mutant zebrafish larvae as a model. Method: We analyzed the conservation of LEAP2 peptide across multiple species and generated leap2 mutants in zebrafish by CRISPR-Cas9, dynamically observed and measured the growth and development of zebrafish larvae from fertilization to 5 day post fertilization (dpf). In situ hybridization, transcriptome sequencing, quantitative real-time PCR and Western blot were used to detect the expression levels of GH and its signaling in early stage of embryonic development. Result: Our data demonstrate that zebrafish with a knockout of the leap2 gene display a significant increase in hatching rate, body length, and the distance between their eyes, all without visible developmental defects in the early stages of development. In addition, both RNA and protein analyses revealed a significant increase in GH expression in leap2 mutant. Conclusion: In general, this study demonstrates that LEAP2 regulates the expression of GH during early development, particularly influencing body length.

LEAP2 is associated with impulsivity and reward sensitivity depending on the nutritional status and decreases with protein intake in humans.

AIM: Liver-expressed antimicrobial peptide 2 (LEAP2) dynamics in human plasma and its association with feeding behaviour remain poorly understood. Therefore, this study aims: (a) to investigate fasting LEAP2 in participants with normal weight or with overweight or mild obesity (OW/OB); (b) to study the association between fasting LEAP2 and anthropometric and metabolic traits, feeding behaviour, LEAP2 genetic variants and blood cell DNA methylation status; and (c) to ascertain postprandial changes in LEAP2 after high protein intake and the association with feeding behaviour and food intake. METHODS: Anthropometric and behavioural measures, genotyping, methylation profiling, plasma glucose and LEAP2 concentrations were assessed in 327 females and males. A subgroup of 123 participants received an ad libitum high-protein meal, and postprandial LEAP2 concentration and behavioural measures were assessed. RESULTS: LEAP2 concentration was higher in participants with OW/OB (p < 0.001) and in females (p < 0.001), and was associated with LEAP2 single nucleotide polymorphisms rs765760 (p = 0.012) and rs803223 (p = 0.019), but not with LEAP2 methylation status. LEAP2 concentration was directly related to glycaemia (p = 0.001) and fullness (p = 0.003) in participants with normal weight, whereas it was associated with body mass index (p = 0.018), waist circumference (p = 0.014) and motor impulsivity in participants with OW/OB (p = 0.005). A negative association with reward responsiveness was observed in participants with OW/OB (p = 0.023). LEAP2 concentration was inversely associated with food intake (p = 0.034) and decreased after a high-protein meal (p < 0.001), particularly in women (p = 0.002). CONCLUSION: Increased LEAP2 in participants with OW/OB is associated with behavioural characteristics of obesity. Our results show sexual dimorphism in LEAP2 concentration before and after food intake and highlight the role of LEAP2 in feeding regulation.

GHSR signalling in perinatal phases is involved in liver metabolism at puberty.

Ghrelin has effects that range from the maturation of the central nervous system to the regulation of energy balance. The production of ghrelin increases significantly during the first weeks of life. Studies have addressed the metabolic effects of liver-expressed antimicrobial peptide 2 (LEAP2) in inhibiting the effects evoked by ghrelin, mainly in glucose homeostasis, insulin resistance, and lipid metabolism. Despite the known roles of ghrelin in the postnatal development, little is known about the long-term metabolic influences of modulation with the endogenous expressed growth hormone secretagogue receptor (GHSR) inverse agonist LEAP2. This study aimed to evaluate the contribution of GHSR signalling during perinatal phases, to neurodevelopment and energy metabolism in young animals, under inverse antagonism by LEAP2[1-14]. For this, two experimental models were used: (i) LEAP2[1-14] injections in female rats during the pregnancy. (ii) Postnatal modulation of GHSR with LEAP2[1-14] or MK677. Perinatal GHSR modulation by LEAP2[1-14] impacts glucose homeostasis in a sex and phase-dependent manner, despite no effects on body weight gain or food intake. Interestingly, liver PEPCK expression was remarkably impacted by LEAP2 injections. The observed results suggests that perinatal LEAP2 exposure can modulate liver metabolism and systemic glucose homeostasis. In addition, these results, although not expressive, may just be the beginning of the metabolic imbalance that will occur in adulthood.

Structure-activity relationships of the intramolecular disulphide bonds in LEAP2, an antimicrobial peptide from Acrossocheilus fasciatus.

BACKGROUND: The liver-expressed antimicrobial peptide 2 (LEAP2) plays a pivotal role in the host's immune response against pathogenic microorganisms. Numerous such antimicrobial peptides have recently been shown to mitigate infection risk in fish, and studying those harboured by the economically important fish Acrossocheilus fasciatus is imperative for enhancing its immune responses against pathogenic microorganisms. In this study, we cloned and sequenced LEAP2 cDNA from A. fasciatus to examine its expression in immune tissues and investigate the structure-activity relationships of its intramolecular disulphide bonds. RESULTS: The predicted amino acid sequence of A. fasciatus LEAP2 was found to include a signal peptide, pro-domain, and mature peptide. Sequence analysis indicated that A. fasciatus LEAP2 is a member of the fish LEAP2A cluster and is closely related to Cyprinus carpio LEAP2A. A. fasciatus LEAP2 transcripts were expressed in various tissues, with the head kidney exhibiting the highest mRNA levels. Upon exposure to Aeromonas hydrophila infection, LEAP2 expression was significantly upregulated in the liver, head kidney, and spleen. A mature peptide of A. fasciatus LEAP2, consisting of two disulphide bonds (Af-LEAP2-cys), and a linear form of the LEAP2 mature peptide (Af-LEAP2) were chemically synthesised. The circular dichroism spectroscopy result shows differences between the secondary structures of Af-LEAP2 and Af-LEAP2-cys, with a lower proportion of alpha helix and a higher proportion of random coil in Af-LEAP2. Af-LEAP2 exhibited potent antimicrobial activity against most tested bacteria, including Acinetobacter guillouiae, Pseudomonas aeruginosa, Staphylococcus saprophyticus, and Staphylococcus warneri. In contrast, Af-LEAP2-cys demonstrated weak or no antibacterial activity against the tested bacteria. Af-LEAP2 had a disruptive effect on bacterial cell membrane integrity, whereas Af-LEAP2-cys did not exhibit this effect. Additionally, neither Af-LEAP2 nor Af-LEAP2-cys displayed any observable ability to hydrolyse the genomic DNA of P. aeruginosa. CONCLUSIONS: Our study provides clear evidence that linear LEAP2 exhibits better antibacterial activity than oxidised LEAP2, thereby confirming, for the first time, this phenomenon in fish.

CRISPR/Cas9-induced LEAP2 and GHSR1a knockout mutant zebrafish displayed abnormal growth and impaired lipid metabolism.

Investigating the principles of fish fat deposition and conducting related research are current focal points in fish nutrition. This study explores the endocrine regulation of LEAP2 and GHSR1a in zebrafish by constructing mutantmodels andexamining the effects of the endocrine factors LEAP2 and its receptor GHSR1a on zebrafish growth, feeding, and liver fat deposition. Compared to the wild type (WT), the mutation of LEAP2 results in increased feeding and decreased swimming in zebrafish. The impact is more pronounced in adult female zebrafish, characterized by increased weight, length, width, and accumulation of lipid droplets in the liver.Incontrast, deficiency in GHSR1a significantly reduces the growth of male zebrafish and markedly decreases liver fat deposition.These research findings indicate the crucial roles of LEAP2 and GHSR1a in zebrafish feeding, growth, and intracellular fat metabolism. This study, for the first time, investigated the endocrine metabolic regulation functions of LEAP2 and GHSR1a in the model organism zebrafish, providing initial insights into their effects and potential mechanisms on zebrafish fat metabolism.

Impacts of Central Administration of the Novel Peptide, LEAP-2, in Different Food Intake Models in Conscious Rats.

Liver-expressed antimicrobial peptide-2 (LEAP-2) has mutual antagonism with ghrelin, which evokes food intake under a freely fed state. Nevertheless, the impact of LEAP-2 on ghrelin under time-restricted feeding (TRF), which has benefits in the context of metabolic disease, is still unknown. This study aims to explore the impact of central administration of LEAP-2 on the ingestion behavior of rats, which was evaluated using their cumulative food intake in the TRF state. Before intracerebroventricular (ICV) administration of O-n-octanoylated ghrelin (0.1 nmol/rat), as a food-stimulatory model, the rats received various doses of LEAP-2 (0.3, 1, 3 nmol/rat, ICV). Cumulative food intake was recorded at 1, 2, 4, 8, 12, and 24 h after ICV injection under 12 h freely fed and TRF states in a light phase. In 12 h freely fed and TRF states, central administration of ghrelin alone induced feeding behavior. Pre-treatment with LEAP-2 (1 and 3 nmol/rat, ICV) suppressed ghrelin-induced food intake in a dose-dependent manner in a 12 h freely fed state instead of a TRF state, which may have disturbed the balance of ghrelin and LEAP-2. This study provides neuroendocrine-based evidence that may explain why TRF sometimes fails in fighting obesity/metabolic dysfunction-associated steatotic liver disease in clinics.

Genetic variants of LEAP2 are associated with anthropometric traits and circulating insulin-like growth factor-1 concentration: A UK Biobank study.

AIM: To test the hypothesis that liver-expressed antimicrobial peptide 2 (LEAP2) genetic variants might influence the susceptibility to human obesity. METHODS: Using data from the UK Biobank, we identified independent LEAP2 gene single nucleotide polymorphisms (SNPs) and examined their associations with obesity traits and serum insulin-like growth factor-1 (IGF-1) concentration. These associations were evaluated for both individual SNPs and after combining them into a genetic risk score (GRSLEAP2) using linear and logistic regression models. Sex-stratified analyses were also conducted. RESULTS: Five SNPs showed positive associations with obesity-related traits. rs57880964 was associated with body mass index (BMI) and waist-to-hip ratio adjusted for BMI (WHRadjBMI), in the total population and among women. Four independent SNPs were positively associated with higher serum IGF-1 concentrations in both men and women. GRSLEAP2 was associated with BMI and WHRadjBMI only in women and with serum IGF-1 concentration in both sexes. CONCLUSIONS: These findings reveal sex-specific associations between key LEAP2 gene variants and several obesity traits, while also indicating a strong independent association of LEAP2 variants with serum IGF-1 concentration.

Preliminary study on the diagnostic value of LEAP-2 and CK18 in biopsy-proven MAFLD.

Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) has become the leading cause of chronic liver disease. Liver biopsy, as the diagnostic gold standard, is invasive and has sampling bias, making it particularly important to search for sensitive and specific biomarkers for diagnosis. Cytokeratin 18 (CK18) M30 and M65 are products of liver cell apoptosis and necrosis, respectively, and liver-expressed antimicrobial peptide 2 (LEAP-2) is a related indicator of glucose and lipid metabolism. Correlation studies have found that all three indicators positively correlate with the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Through comparison of diagnostic values, it was found that CK18 M65 can better distinguish between healthy individuals and MAFLD; LEAP-2 can effectively distinguish MAFLD from other liver diseases, especially ALD.

A long-acting LEAP2 analog reduces hepatic steatosis and inflammation and causes marked weight loss in mice.

OBJECTIVE: The number of individuals affected by metabolic dysfunction associated fatty liver disease [1] is on the rise, yet hormonal contributors to the condition remain incompletely described and only a single FDA-approved treatment is available. Some studies suggest that the hormones ghrelin and LEAP2, which act as agonist and antagonist/inverse agonist, respectively, for the G protein coupled receptor GHSR, may influence the development of MAFLD. For instance, ghrelin increases hepatic fat whereas synthetic GHSR antagonists do the opposite. Also, hepatic steatosis is less prominent in standard chow-fed ghrelin-KO mice but more prominent in 42% high-fat diet-fed female LEAP2-KO mice. METHODS: Here, we sought to determine the therapeutic potential of a long-acting LEAP2 analog (LA-LEAP2) to treat MAFLD in mice. LEAP2-KO and wild-type littermate mice were fed a Gubra-Amylin-NASH (GAN) diet for 10 or 40 wks, with some randomized to an additional 28 or 10 days of GAN diet, respectively, while treated with LA-LEAP2 vs Vehicle. Various metabolic parameters were followed and biochemical and histological assessments of MAFLD were made. RESULTS: Among the most notable metabolic effects, daily LA-LEAP2 administration to both LEAP2-KO and wild-type littermates during the final 4 wks of a 14 wk-long GAN diet challenge markedly reduced liver weight, hepatic triglycerides, plasma ALT, hepatic microvesicular steatosis, hepatic lobular inflammation, NASH activity scores, and prevalence of higher-grade fibrosis. These changes were accompanied by prominent reductions in body weight, without effects on food intake, and reduced plasma total cholesterol. Daily LA-LEAP2 administration during the final 10 d of a 41.5 wk-long GAN diet challenge also reduced body weight, plasma ALT, and plasma total cholesterol in LEAP2-KO and wild-type littermates and prevalence of higher grade fibrosis in LEAP2-KO mice. CONCLUSIONS: Administration of LA-LEAP2 to mice fed a MAFLD-prone diet markedly improves several facets of MAFLD, including hepatic steatosis, hepatic lobular inflammation, higher-grade hepatic fibrosis, and transaminitis. These changes are accompanied by prominent reductions in body weight and lowered plasma total cholesterol. Taken together, these data suggest that LEAP2 analogs such as LA-LEAP2 hold promise for the treatment of MAFLD and obesity.

Impact of Ghrelin on Islet Size in Nonpregnant and Pregnant Female Mice.

Reducing ghrelin by ghrelin gene knockout (GKO), ghrelin-cell ablation, or high-fat diet feeding increases islet size and ß-cell mass in male mice. Here we determined if reducing ghrelin also enlarges islets in females and if pregnancy-associated changes in islet size are related to reduced ghrelin. Islet size and ß-cell mass were larger (P = .057 for ß-cell mass) in female GKO mice. Pregnancy was associated with reduced ghrelin and increased liver-expressed antimicrobial peptide-2 (LEAP2; a ghrelin receptor antagonist) in wild-type mice. Ghrelin deletion and pregnancy each increased islet size (by ∼19.9-30.2% and ∼34.9-46.4%, respectively), percentage of large islets (>25 µm2×103, by ∼21.8-42% and ∼21.2-41.2%, respectively), and ß-cell mass (by ∼15.7-23.8% and ∼65.2-76.8%, respectively). Neither islet cross-sectional area, ß-cell cross-sectional area, nor ß-cell mass correlated with plasma ghrelin, although all positively correlated with LEAP2 (P = .081 for islet cross-sectional area). In ad lib-fed mice, there was an effect of pregnancy, but not ghrelin deletion, to change (raise) plasma insulin without impacting blood glucose. Similarly, there was an effect of pregnancy, but not ghrelin deletion, to change (lower) blood glucose area under the curve during a glucose tolerance test. Thus, genetic deletion of ghrelin increases islet size and ß-cell cross-sectional area in female mice, similar to males. Yet, despite pregnancy-associated reductions in ghrelin, other factors appear to govern islet enlargement and changes to insulin sensitivity and glucose tolerance in the setting of pregnancy. In the case of islet size and ß-cell mass, one of those factors may be the pregnancy-associated increase in LEAP2.

Decoding the influence of central LEAP2 on food intake and its effect on accumbal dopamine release.

The gut-brain peptide ghrelin and its receptor are established as a regulator of hunger and reward-processing. However, the recently recognized ghrelin receptor inverse agonist, liver-expressed antimicrobial peptide 2 (LEAP2), is less characterized. The present study aimed to elucidate LEAP2s central effect on reward-related behaviors through feeding and its mechanism. LEAP2 was administrated centrally in mice and effectively reduced feeding and intake of palatable foods. Strikingly, LEAP2s effect on feeding was correlated to the preference of the palatable food. Further, LEAP2 reduced the rewarding memory of high preference foods, and attenuated the accumbal dopamine release associated with palatable food exposure and eating. Interestingly, LEAP2 was widely expressed in the brain, and particularly in reward-related brain areas such as the laterodorsal tegmental area (LDTg). This expression was markedly altered when allowed free access to palatable foods. Accordingly, infusion of LEAP2 into LDTg was sufficient to transiently reduce acute palatable food intake. Taken together, the present results show that central LEAP2 has a profound effect on dopaminergic reward signaling associated with food and affects several aspects of feeding. The present study highlights LEAP2s effect on reward, which may have applications for obesity and other reward-related psychiatric and neurological disorders.

Intestinal expression profiles and hepatic expression of LEAP2, ghrelin and their common receptor, GHSR, in humans.

Liver-expressed antimicrobial peptide 2 (LEAP2) and ghrelin have reciprocal effects on their common receptor, the growth hormone secretagogue receptor (GHSR). Ghrelin is considered a gastric hormone and LEAP2 a liver-derived hormone and both have been proposed to be involved in the pathophysiology of obesity and type 2 diabetes (T2D). We investigated the mRNA expression of LEAP2, ghrelin and GHSR along the intestinal tract of individuals with and without TD2, and in the liver of men with and without obesity. Mucosal biopsies retrieved with 30-cm intervals throughout the small intestine and from 7 well-defined locations along the large intestine from 12 individuals with T2D and 12 healthy controls together with liver biopsies from 15 men with obesity and 15 lean men were subjected to bulk transcriptomics analysis. Both in individuals with and without T2D, mRNA expression of LEAP2 increased through the small intestine until dropping at the ileocecal valve, with little LEAP2 mRNA expression in the large intestine. Pronounced LEAP2 expression was observed in the liver of men with and without obesity. Robust ghrelin mRNA expression was observed in the duodenum of individuals with and without T2D, gradually decreasing along the small intestine with little expression in the large intestine. Ghrelin mRNA expression was not detected in the liver biopsies, and GHSR mRNA expression was not. In conclusion, we provide unique mRNA expression profiles of LEAP2, ghrelin and GHSR along the human intestinal tract showing no T2D-associated changes, and in the liver showing no differences between men with and without obesity.

Quail GHRL and LEAP2 gene cloning, polymorphism detection, phylogenetic analysis, tissue expression profiling and its association analysis with feed intake.

The GHRL, LEAP2, and GHSR system have recently been identified as important regulators of feed intake in mammals and chickens. However, the complete cloning of the quail GHRL (qGHRL) and quail LEAP2 (qLEAP2) genes, as well as their association with feed intake, remains unclear. This study cloned the entire qGHRL and qLEAP2 cDNA sequence in Chinese yellow quail (Coturnix japonica), including the 5' and 3' untranslated regions. Sanger sequencing analysis revealed no missense mutations in the coding region of qGHRL and qLEAP2. Subsequently, phylogenetic analysis and protein homology alignment were conducted on the qGHRL and qLEAP2 in major poultry species. The findings of this research indicated that the qGHRL and qLEAP2 sequences exhibit a high degree of similarity with those of chicken and turkey. Specifically, the N-terminal 6 amino acids of GHRL mature peptides and all the mature peptide sequence of LEAP2 exhibited consistent patterns across all species examined. The analysis of tissue gene expression profiles indicated that qGHRL was primarily expressed in the proventriculus and brain tissue, whereas qLEAP2 exhibited higher expression levels in the intestinal tissue, kidney, and liver tissue, differing slightly from previous studies conducted on chicken. It is necessary to investigate the significance of elevated expression of qGHRL in brain and qLEAP2 in kidney in the future. Further research has shown that the expression of qLEAP2 can quickly respond to changes in different energy states, whereas qGHRL does not exhibit the same capability. Overall, this study successfully cloned the complete cDNA sequences of qGHRL and qLEAP2, and conducted a comprehensive examination of their tissue expression profiles and gene expression levels in the main expressing organs across different energy states. Our current findings suggested that qLEAP2 is highly expressed in the liver, intestine, and kidney, and its expression level is regulated by feed intake.

Gait-modifying effects of augmented-reality cueing in people with Parkinson's disease.

Introduction: External cueing can improve gait in people with Parkinson's disease (PD), but there is a need for wearable, personalized and flexible cueing techniques that can exploit the power of action-relevant visual cues. Augmented Reality (AR) involving headsets or glasses represents a promising technology in those regards. This study examines the gait-modifying effects of real-world and AR cueing in people with PD. Methods: 21 people with PD performed walking tasks augmented with either real-world or AR cues, imposing changes in gait speed, step length, crossing step length, and step height. Two different AR headsets, differing in AR field of view (AR-FOV) size, were used to evaluate potential AR-FOV-size effects on the gait-modifying effects of AR cues as well as on the head orientation required for interacting with them. Results: Participants modified their gait speed, step length, and crossing step length significantly to changes in both real-world and AR cues, with step lengths also being statistically equivalent to those imposed. Due to technical issues, step-height modulation could not be analyzed. AR-FOV size had no significant effect on gait modifications, although small differences in head orientation were observed when interacting with nearby objects between AR headsets. Conclusion: People with PD can modify their gait to AR cues as effectively as to real-world cues with state-of-the-art AR headsets, for which AR-FOV size is no longer a limiting factor. Future studies are warranted to explore the merit of a library of cue modalities and individually-tailored AR cueing for facilitating gait in real-world environments.

Identification of antibacterial activity of liver-expressed antimicrobial peptide 2 (LEAP2) from primitive vertebrate lamprey.

Liver-expressed antimicrobial peptide 2 (LEAP2) is a member of the antimicrobial peptides family and plays a key role in the innate immune system of organisms. LEAP2 orthologs have been identified from a variety of fish species, however, its function in primitive vertebrates has not been clarified. In this study, we cloned and identified Lc-LEAP2 from the primitive jawless vertebrate lamprey (Lethenteron camtschaticum) which includes a 25 amino acids signal peptide and a mature peptide of 47 amino acids. Although sequence similarity was low compared to other species, the mature Lc-LEAP2 possesses four conserved cysteine residues, forming a core structure with two disulfide bonds between the cysteine residues in the relative 1-3 (Cys 58 and Cys 69) and 2-4 (Cys 64 and Cys 74) positions. Lc-LEAP2 was most abundantly expressed in the muscle, supraneural body and buccal gland of lamprey, and was significantly upregulated during LPS and Poly I:C stimulations. The mature peptide was synthesized and characterized for its antibacterial activity against different bacteria. Lc-LEAP2 possessed inhibition of a wide range of bacteria with a dose-dependence, disrupting the integrity of bacterial cell membranes and binding to bacterial genomic DNA, although its inhibitory function is weak compared to that of higher vertebrates. These data suggest that Lc-LEAP2 plays an important role in the innate immunity of lamprey and is of great value in improving resistance to pathogens. In addition, the antimicrobial mechanism of LEAP2 has been highly conserved since its emergence in primitive vertebrates.

The effects of ghrelin and LEAP-2 in energy homeostasis are modulated by thermoneutrality, high-fat diet and aging.

PURPOSE: Liver-expressed antimicrobial peptide 2 (LEAP-2) has been recently identified as the endogenous non-competitive allosteric antagonist of the growth hormone secretagogue receptor 1a (GHSR1a). In rodents, LEAP-2 blunts ghrelin-induced feeding and its plasma levels are modulated in response to nutritional status, being decreased upon fasting and increased in high-fat diet (HFD) fed mice. Clinical data support the regulation of circulating LEAP-2 by nutrient availability in humans. In this work, our primary objective was to examine the chronic effects of ghrelin and LEAP-2 administration on food intake, adiposity, and energy expenditure in young mice subjected to standard and HFD at both room temperature and at thermoneutrality. Furthermore, we aimed to assess the impact of these two hormones on aging mice. RESULTS: Our results indicate that LEAP-2 produces a significant decrease of body weight and adiposity, an increase in energy expenditure, and activation of the thermogenic program in white and brown adipose tissue depots. However, this effect is not maintained under HFD or under thermoneutral conditions and is only partially observed in aging mice. CONCLUSION: In summary our studies describe the central effects of LEAP-2 within distinct experimental contexts, and contribute to the comprehension of LEAP-2's role in energy metabolism.

Molecular characterization, antibacterial and immunoregulatory activities of liver-expressed antimicrobial peptide 2 in black rockfish, Sebastes schlegelii.

LEAP2 (liver expression antimicrobial peptide 2), is an antimicrobial peptide widely found in vertebrates and mainly expressed in liver. LEAP2 plays a vital role in host innate immunity. In teleosts, a number of LEAP2 homologs have been reported, but their in vivo effects on host defense are still limited. In this study, a LEAP2 homolog (SsLEAP2) was identified from black rockfish, Sebastes schlegelii, and its structure, expression as well as biological functions were analyzed. The results showed that the open reading frame of SsLEAP2 is 300 bp, with a 5'- untranslated region (UTR) of 375 bp and a 3' - UTR of 238 bp. The deduced amino acid sequence of SsLEAP2 shares the highest overall identity (96.97%) with LEAP2 of Sebastes umbrosus. SsLEAP2 possesses conserved LEAP2 features, including a signal peptide sequence, a prodomain and a mature peptide, in which four well-conserved cysteines formed two intrachain disulphide domain. The expression of SsLEAP2 was highest in liver and could be induced by experimental infection with Listonella anguillarum, Edwardsiealla piscicida and Rock bream iridovirus C1 (RBIV-C1). Recombinant SsLEAP2 (rSsLEAP2) purified from Escherichia coli was able to bind with various Gram-positive and Gram-negative bacteria. Further analysis showed that rSsLEAP2 could enhance the respiratory burst activity, and induce the expression of immune genes including interleukin 1-ß (IL-1ß) and serum amyloid A (SAA) in macrophages; additionally, rSsLEAP2 could also promote the proliferation and chemotactic of peripheral blood lymphocytes (PBLs). In vivo experiments indicated that overexpression of SsLEAP2 could inhibit bacterial infection, and increase the expression level of immune genes including IL-1ß, tumor necrosis factor ligand superfamily member 13B (TNF13B) and haptoglobin (HP); conversely, knock down of SsLEAP2 promoted bacterial infection and decreased the expression level of above genes. Taken together, these results suggest that SsLEAP2 is a novel LEAP2 homolog that possesses apparent antibacterial activity and immunoregulatory property, thus plays a critical role in host defense against pathogens invasion.

Pre-prandial plasma liver-expressed antimicrobial peptide 2 (LEAP2) concentration in humans is inversely associated with hunger sensation in a ghrelin independent manner.

PURPOSE: The liver-expressed antimicrobial peptide 2 (LEAP2) is a newly recognized peptide hormone that acts via the growth hormone secretagogue receptor (GHSR) blunting the effects of ghrelin and displaying ghrelin-independent actions. Since the implications of LEAP2 are beginning to be elucidated, we investigated if plasma LEAP2 concentration varies with feeding status or sex and whether it is associated with glucose metabolism and appetite sensations. METHODS: We performed a single test meal study, in which plasma concentrations of LEAP2, ghrelin, insulin and glucose as well as visual analogue scales for hunger, desire to eat, prospective food consumption, fullness were assessed before and 60 min after breakfast in 44 participants (n = 21 females) with normal weight (NW) or overweight/obesity (OW/OB). RESULTS: Pre-prandial plasma LEAP2 concentration was ~ 1.6-fold higher whereas ghrelin was ~ 2.0-fold lower in individuals with OW/OB (p < 0.001) independently of sex. After adjusting for body mass index (BMI) and sex, pre-prandial plasma LEAP2 concentration displayed a direct relationship with BMI (ß: 0.09; 95%CI: 0.05, 0.13; p < 0.001), fat mass (ß: 0.05; 95%CI: 0.01, 0.09; p = 0.010) and glycemia (ß: 0.24; 95%CI: 0.05, 0.43; p = 0.021), whereas plasma ghrelin concentration displayed an inverse relationship with BMI and fat mass but not with glycemia. Postprandial plasma LEAP2 concentration increased ~ 58% in females with OW/OB (p = 0.045) but not in females with NW or in males. Pre-prandial plasma LEAP2 concentration displayed an inverse relationship with hunger score (ß: - 11.16; 95% CI: - 18.52, - 3.79; p = 0.004), in a BMI-, sex- and ghrelin-independent manner. CONCLUSIONS: LEAP2 emerges as a key hormone implicated in the regulation of metabolism and appetite in humans. TRIAL REGISTRATION: The study was retrospectively registered in clinicaltrials.gov (April 2023). CLINICALTRIALS: gov Identifier: NCT05815641.