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Muscle wasting diseases, such as cancer cachexia and age-associated sarcopenia, have a profound and detrimental impact on functional independence, quality of life, and survival. Our understanding of the underlying mechanisms is currently limited, which has significantly hindered the development of targeted therapies. In this study, we explored the possibility that the streptococcal quorum sensing peptide Competence Stimulating Peptide 7 (CSP-7) might be a previously unidentified contributor to clinical muscle wasting. We found that CSP-7 selectively triggers muscle cell inflammation in vitro, specifically the release of IL-6. Furthermore, we demonstrated that CSP-7 can traverse the gastrointestinal barrier in vitro and is present in the systemic circulation in humans in vivo. Importantly, CSP-7 was associated with a muscle wasting phenotype in mice in vivo. Overall, our findings provide new mechanistic insights into the pathophysiology of muscle inflammation and wasting., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The sensitive and specific detection of peptides at low levels in biofluids is critical to increase the lab-to-human translation of peptidomic research. An interesting group of peptides with increasing evidence for involvement in human diseases are quorum sensing peptides. To obtain more reliable conclusions on peptide measurands in biofluids, a selection of often neglected parts of the analytical process using LC-MS were investigated, with novel approaches recommended for each part. Quorum sensing peptides were used as the main model-peptides. The peptidomic parts investigated and discussed here are: Our work addresses aQbD-approached solutions to these challenges, encompassing sample stabilization measures, a suitable peptide anti-adsorption tool, judicious choice of injection solvent versus gradient system and optimal duty cycle parameters. Our recommendations will improve the peptidomics bio-analytics of not only quorum sensing peptides, but can also be of value for other measurands at low concentrations., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Quorum-sensing peptides (QSPs) are bacterial peptides traditionally considered only as inter-bacterial communication molecules. Recently, their involvement in microbiome-host interactions influencing host diseases such as cancer and sarcopenia were explored. However, it is still unknown to what extent these peptides have the potential to modulate the immune system. In this proof-of-concept study, we screened 89 QSPs for their potential to induce IL-6 and TNFα in murine splenocytes and J774 macrophages. Confirmatory experiments on the positive screening-hits were conducted using murine splenocytes and human PBMCs of different ages. Finally, to investigate the biological relevance of immunomodulatory QSPs, we analysed plasma in a human cohort for the presence of the immunomodulatory QSP Q010. To do this, we used a newly developed UHPLC-MS/MS method. Our findings indicated that specific QSPs activate immune cells in vitro, with Q007, Q010, Q017 and Q212 being the top four screening hits. Q007 and Q010 were affirmed in subsequent confirmatory experiments using murine splenocytes and human PBMCs. Finally, Q010 was detected in human plasma, demonstrating for the first time the presence of an immunomodulatory QSP in human circulation. In conclusion, our data are the first evidence indicating the potential of biologically relevant quorum-sensing peptides to modulate the immune system.

Background: Colorectal cancer, one of the most common malignancies worldwide, is associated with a high mortality rate, mainly caused by metastasis. Comparative metagenome-wide association analyses of healthy individuals and cancer patients suggest a role for the human intestinal microbiota in tumor progression. However, the microbial molecules involved in host-microbe communication are largely unknown, with current studies mainly focusing on short-chain fatty acids and amino acid metabolites as potential mediators. Quorum sensing peptides are not yet considered in this context since their presence in vivo and their ability to affect host cells have not been reported so far., Results: Here, we show that EntF*, a metabolite of the quorum sensing peptide EntF produced by Enterococcus faecium, is naturally present in mice bloodstream. Moreover, by using an orthotopic mouse model, we show that EntF* promotes colorectal cancer metastasis in vivo, with metastatic lesions in liver and lung tissues. In vitro tests suggest that EntF* regulates E-cadherin expression and consequently the epithelial-mesenchymal transition, via the CXCR4 receptor. In addition, alanine-scanning analysis indicates that the first, second, sixth, and tenth amino acid of EntF* are critical for epithelial-mesenchymal transition and tumor metastasis., Conclusion: Our work identifies a new class of molecules, quorum sensing peptides, as potential regulators of host-microbe interactions. We prove, for the first time, the presence of a selected quorum sensing peptide metabolite in a mouse model, and we demonstrate its effects on colorectal cancer metastasis. We believe that our work represents a starting point for future investigations on the role of microbiome in colorectal cancer metastasis and for the development of novel bio-therapeutics in other disease areas., (© 2022. The Author(s).)

The development of analytical methods for the detection of peptides at the nanomolar level can be challenging. Peptides can suffer from adsorption, rendering the detection of peptides at these low levels difficult. A subset of peptides are the quorum sensing peptides, which are bacterial communication molecules demonstrating possible host effects as well. However, their direct presence in human biofluids has only rarely been reported. Therefore, a UHPLC-MS/MS method capable of detecting 15 selected Streptococcal competence stimulating quorum sensing peptides at the nanomolar level in human saliva was developed. This method, using an anti-adsorption diluent, was applied on saliva samples obtained from 38 healthy donors. Six donors did have a positive hit for at least one of three competence stimulating quorum sensing peptides using a triple quadrupole assay. These observations indicate that Streptococcus species produce quorum sensing peptides in the human oral cavity., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Introduction: Hospitalization is associated with acute changes in sarcopenia status in older people, but the influencing factors are not fully understood. Pre-admission care dependency level as a risk factor has not yet been investigated., Objective: Evaluate if pre-admission care dependency level is an independent predictor of sarcopenia changes following hospitalization., Setting and Subjects: Data came from the Sarcopenia 9+ EAMA Project, a European prospective multi-centre study. For this study, 227 hospitalised older people were included from four different hospitals in Belgium, Spain and Poland, between 18 February 2019 and 5 September 2020., Methods: Sarcopenia status at admission and discharge were calculated using a combined score (desirability value) based on muscle mass (calf circumference), strength (grip) and function (walking speed). Ratio of admission to discharge status was the outcome (desirability ratio; 1.00 meaning no difference). Predictor variable was the pre-admission care dependency level, classified into three groups: independent older people living at home, dependent older people living at home and older people living in a care home. Linear regression models were applied, considering potential confounders., Results: Mean desirability ratio for dependent older people living at home ('middle dependent group') was lower (0.89) compared to independent older people (0.98; regression coefficient -0.09 [95% CI -0.16, -0.02]) and care home patients (1.05; -0.16 [95% CI -0.01, -0.31]). Adjusting for potential confounders or using another statistical approach did not affect the main results., Conclusion: Dependent older people living at home were at higher risk of deterioration in sarcopenia status following hospitalization. In-depth studies investigating causes and potential interventions of these findings are needed., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

The COVID-19 pandemic has disrupted life throughout the world. Newly developed vaccines promise relief to people who live in high-income countries, although vaccines and expensive new treatments are unlikely to arrive in time to help people who live in low-and middle-income countries. The pathogenesis of COVID-19 is characterized by endothelial dysfunction. Several widely available drugs like statins, ACE inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) have immunometabolic activities that (among other things) maintain or restore endothelial cell function. For this reason, we undertook an observational study in four Belgian hospitals to determine whether in-hospital treatment with these drugs could improve survival in 959 COVID-19 patients. We found that treatment with statins and ACEIs/ARBs reduced 28-day mortality in hospitalized COVID-19 patients. Moreover, combination treatment with these drugs resulted in a 3-fold reduction in the odds of hospital mortality (OR = 0.33; 95% CI 0.17-0.69). These findings were in general agreement with other published studies. Additional observational studies and clinical trials are needed to convincingly show that in-hospital treatment with statins, ACEIs/ARBs, and especially their combination saves lives.

Quorum sensing peptides (QSPs) are bacterial peptides produced by Gram-positive bacteria to communicate with their peers in a cell-density dependent manner. These peptides do not only act as interbacterial communication signals, but can also have effects on the host. Compelling evidence demonstrates the presence of a gut-brain axis and more specifically, the role of the gut microbiota in microglial functioning. The aim of this study is to investigate microglial activating properties of a selected QSP (PapRIV) which is produced by Bacillus cereus species. PapRIV showed in vitro activating properties of BV-2 microglia cells and was able to cross the in vitro Caco-2 cell model and reach the brain. In vivo peptide presence was also demonstrated in mouse plasma. The peptide caused induction of IL-6, TNFα and ROS expression and increased the fraction of ameboid BV-2 microglia cells in an NF-κB dependent manner. Different metabolites were identified in serum, of which the main metabolite still remained active. PapRIV is thus able to cross the gastro-intestinal tract and the blood-brain barrier and shows in vitro activating properties in BV-2 microglia cells, hereby indicating a potential role of this quorum sensing peptide in gut-brain interaction.

Objectives: Angiotensin-converting enzyme inhibitors (ACEi), angiotensin II receptor blockers (ARBs), and HMG-CoA reductase inhibitors ("statins") have been hypothesized to affect COVID-19 severity. However, up to now, no studies investigating this association have been conducted in the most vulnerable and affected population groups (ie, older adults residing in nursing homes). The objective of this study was to explore the association of ACEi/ARB and/or statins with clinical manifestations in COVID-19-infected older adults residing in nursing homes., Design: We undertook a retrospective multicenter cohort study to analyze the association between ACEi/ARB and/or statin use with clinical outcome of COVID-19. The outcomes were (1) serious COVID-19 defined as long-stay hospital admission or death within 14 days of disease onset, and (2) asymptomatic (ie, no disease symptoms in the whole study period while still being diagnosed by polymerase chain reaction)., Setting and Participants: A total of 154 COVID-19-positive subjects were identified, residing in 1 of 2 Belgian nursing homes that experienced similar COVID-19 outbreaks., Measures: Logistic regression models were applied with age, sex, functional status, diabetes, and hypertension as covariates., Results: We found a statistically significant association between statin intake and the absence of symptoms during COVID-19 (odds ratio [OR] 2.91; confidence interval [CI] 1.27-6.71), which remained statistically significant after adjusting for covariates (OR 2.65; CI 1.13-6.68). Although the effects of statin intake on serious clinical outcome were in the same beneficial direction, these were not statistically significant (OR 0.75; CI 0.24-1.87). There was also no statistically significant association between ACEi/ARB and asymptomatic status (OR 2.72; CI 0.59-25.1) or serious clinical outcome (OR 0.48; CI 0.10-1.97)., Conclusions and Implications: Our data indicate that statin intake in older, frail adults could be associated with a considerable beneficial effect on COVID-19 clinical symptoms. The role of statins and renin-angiotensin system drugs needs to be further explored in larger observational studies as well as randomized clinical trials., (Copyright © 2020 AMDA – The Society for Post-Acute and Long-Term Care Medicine. All rights reserved.)

Finding adequate biomarkers for rapid and accurate disease detection, prognosis, and therapy is increasingly important. Quorum-sensing peptides are herein a new emerging group, produced by bacteria, fungi, protozoa, and viruses, with blood being the most straightforward sample type to detect/quantitate them. However, detailed information about suitable blood sample collection methods and storage conditions for measuring these quorum-sensing peptides hampers further clinical research and development. Here, we first tested the time-dependent stability of a set of chemically diverse quorum-sensing peptides, spiked in blood at different temperatures (4, 21, and 37 °C) in four different ethylenediamine tetraacetic acid (EDTA)-containing plasma tubes (with different protein-stabilizing additives) over a period of up to 7.5 h. Next, we determined the storage stability of these quorum-sensing peptides in plasma at different temperatures (4, -35, and -80 °C). UPLC/MS-MS was used to selectively detect and quantify the spiked quorum-sensing peptides. The results of this study indicate that a cost-effective tube, designed for traditional proteomics and stored at 4 °C, is the preferred collection condition when quorum-sensing peptides need to be detected/quantified in human plasma. When the tubes are handled at room temperature (21 °C), a more specialized tube is required. Long-term storage of plasma samples, even under low-temperature conditions (-80 °C), indicates rapid degradation of certain quorum-sensing peptides., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Skeletal muscle makes up the largest part of human body mass and a good maintenance of this organ is essential for general health. In accordance, muscle wasting, a frequent phenomenon in many diseases, is associated with functional decline and a decrease in quality of life. Unfortunately, due to a lack of knowledge of the underlying pathophysiology, no targeted therapies exist today to encounter muscle wasting. Recent studies suggest a role for the gut microbiome in muscle wasting, without the mediators of this gut-muscle axis being identified. Here we evaluated the possible effects of 75 quorum sensing molecules (QSM), traditionally only seen as intra-bacterial communication molecules, on C2C12 muscle cells, studying viability, differentiation, inflammation, mitochondrial changes and protein degradation as biological outcomes. The responses were evaluated using different approaches: median absolute deviation, quartiles, strictly standardized mean difference and robust strictly standardized mean difference. This study resulted in 30 QSM, with effects observed on C2C12 cells. Known producers of the 27 peptide QSM belong to species of the genus Staphylococcus, Streptococcus, Enterococcus, Bacillus, Lactobacillus and Escherichia, while the 3 non-peptide QSM are produced by a broad range of Gram-positive and Gram-negative bacteria. Altogether, these proof-of-concept findings provide the first evidence that QSM produced by microbiota play a role in the gut-muscle axis, opening new perspectives for diagnostic and therapeutic targets in muscle wasting diseases., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Sarcopenia, defined as the pathological decline in muscle mass, muscle strength and physical performance with aging, has become one of the geriatric giants because of its increasing prevalence and devastating health effects. The Belgian Society of Gerontology and Geriatrics (BSGG) is currently developing evidence-based guidelines for the prevention and therapy of sarcopenia for use in broad clinical practice. This systematic review summarizes the results of the Working Group on Pharmacology., Objective: Our objective was to provide an evidence-based overview of the possible pharmacological interventions for sarcopenia with a focus on interventions that have already been studied in systematic reviews or meta-analyses., Methods: We conducted a systematic umbrella review. Using the electronic databases PubMed and Web of Science, we identified systematic reviews and meta-analyses that assessed the effect of pharmacological interventions on criteria for sarcopenia in subjects aged ≥ 65 years. Study selection, quality assessment and data extraction were performed by two independent reviewers., Results: We identified seven systematic reviews or meta-analyses, encompassing ten pharmacological interventions: vitamin D, combined estrogen-progesterone, dehydroepiandrosterone, growth hormone, growth hormone-releasing hormone, combined testosterone-growth hormone, insulin-like growth factor-1, pioglitazone, testosterone and angiotensin-converting enzyme inhibitors. Importantly, very few systematic reviews or meta-analyses clearly mentioned baseline sarcopenia status. Therefore, our recommendations are generalised to older people, without specifying whether the muscle effect is more effective in healthy, pre-sarcopenic or sarcopenic older people. Vitamin D had a significant effect on muscle strength and physical performance, especially in women with low baseline values (< 25 nmol/l). Adverse events were rare. Testosterone had a strong effect on muscle mass and a modest to minimal effect on muscle strength and physical performance, respectively, when supplementing men with low serum levels (< 200-300 ng/dl). The adverse events were rare and mild. Insufficient evidence was available to recommend other pharmacological interventions., Conclusion: Only vitamin D, especially in older women, and testosterone in older men with clinical muscle weakness and low testosterone serum levels can be justified in daily clinical practice to improve muscle mass, muscle strength and/or physical performance.

Sarcopenia - or the loss of muscle mass, strength and function with ageing - represents an important health issue of the twenty-first century because of its devastating effects in addition to an increased prevalence of aged people. The devastating health effects of sarcopenia are multiple: an increased falls risk, a decreased physical ability and quality of life and an independent increase of all-cause mortality. Although the ultimate remedy for sarcopenia yet has to be found, some interventions have proven their merit and might be of practical use in clinical practice, especially for geriatricians, who deal most with sarcopenia. This review intends to summarize the current therapeutic interventions, their proposed mechanism of action as well as their clinical value. The results of our review highlight the importance of exercise (50% resistance training, 50% endurance training), nutrition (25-30 g proteins with essential amino acids every meal and long-chain ω-3 fatty acids) and limitation of alcohol and smoking. In addition, studies also suggest a place for vitamin D (aim serum levels >30 ng/L), testosterone (aim serum levels >300 ng/dL) and creatine (15-20 g/d for five days, thereafter 3-5 g/d). In conclusion, although more studies are needed to elucidate the exact effectiveness and safety of many sarcopenia interventions, the current evidence already provides clinically useful information, which might benefit the patient with (pre-)sarcopenia.

Many analogues of the glycolipid alpha-galactosylceramide (α-GalCer) are known to activate iNKT cells through their interaction with CD1d-expressing antigen-presenting cells, inducing the release of Th1 and Th2 cytokines. Because of iNKT cell involvement and associated Th1/Th2 cytokine changes in a broad spectrum of human diseases, the design of iNKT cell ligands with selective Th1 and Th2 properties has been the subject of extensive research. This search for novel iNKT cell ligands requires refined structural insights. Here we will visualize the chemical space of 333 currently known iNKT cell activators, including several newly tested analogues, by more than 3000 chemical descriptors which were calculated for each individual analogue. To evaluate the immunological responses we analyzed five different cytokines in five different test-systems. We linked the chemical space to the immunological space using a system biology computational approach resulting in highly sensitive and specific predictive models. Moreover, these models correspond with the current insights of iNKT cell activation by α-GalCer analogues, explaining the Th1 and Th2 biased responses, downstream of iNKT cell activation. We anticipate that such models will be of great value for the future design of iNKT cell agonists.