Plasma Metabolite Profiling in the Search for Early-Stage Biomarkers for Lung Cancer: Some Important Breakthroughs.

Lung cancer is the leading cause of cancer-related mortality worldwide. In order to improve its overall survival, early diagnosis is required. Since current screening methods still face some pitfalls, such as high false positive rates for low-dose computed tomography, researchers are still looking for early biomarkers to complement existing screening techniques in order to provide a safe, faster, and more accurate diagnosis. Biomarkers are biological molecules found in body fluids, such as plasma, that can be used to diagnose a condition or disease. Metabolomics has already been shown to be a powerful tool in the search for cancer biomarkers since cancer cells are characterized by impaired metabolism, resulting in an adapted plasma metabolite profile. The metabolite profile can be determined using nuclear magnetic resonance, or NMR. Although metabolomics and NMR metabolite profiling of blood plasma are still under investigation, there is already evidence for its potential for early-stage lung cancer diagnosis, therapy response, and follow-up monitoring. This review highlights some key breakthroughs in this research field, where the most significant biomarkers will be discussed in relation to their metabolic pathways and in light of the altered cancer metabolism.

Randomised, controlled, open-label pragmatic trial evaluating changes in functional exercise capacity after primary care PUlmonary REhabilitation in patients with long COVID: protocol of the PuRe-COVID trial in Belgium.

INTRODUCTION: Long COVID is a prevalent condition with many multisystemic symptoms, such as fatigue, dyspnoea, muscle weakness, anxiety, depression and sleep difficulties, impacting daily life and (social and physical) functioning. Pulmonary rehabilitation (PR) may improve physical status and symptoms of patients with long COVID, yet the evidence is limited. Therefore, this trial aims to study the effect of primary care PR on exercise capacity, symptoms, physical activity and sleep in patients with long COVID. METHODS AND ANALYSIS: PuRe-COVID is a prospective, pragmatic, open-label, randomised controlled trial. A sample of 134 adult patients with long COVID will be randomised to a 12 week PR programme in primary care, supervised by a physiotherapist or to a control group, following no PR. A 3 month and 6 month follow-up period is foreseen. The primary endpoint will be the change in exercise capacity measured by 6-minute walk distance (6MWD) at 12 weeks, hypothesising a more significant improvement in the PR group. Other parameters, such as pulmonary function tests (including maximal inspiratory pressure/maximal expiratory pressure), patient-reported outcomes (COPD Assessment Test, modified Medical Research Council Dyspnoea Scale, Checklist Individual Strength, post-COVID-19 Functional Status, Nijmegen questionnaire, Hospital Anxiety and Depression Scale, Work Productivity and Activity Impairment Questionnaire and EuroQol-5D-5L), physical activity measured by an activity tracker, hand grip strength and sleep efficiency, are secondary and exploratory outcomes.The recruitment started on 19 April 2022, and 52 patients were included as of 14 December 2022. ETHICS AND DISSEMINATION: Ethical approval was obtained in Belgium from the relevant institutional review boards on 21 February 2022 (Antwerp University Hospital, approval number 2022-3067) and on 1 April 2022 (Ziekenhuis Oost-Limburg in Genk, approval number Z-2022-01). Findings from this randomised controlled trial will be disseminated in peer-reviewed publications and presentations at international scientific meetings. TRIAL REGISTRATION NUMBER: NCT05244044.

NMR-Metabolomics Reveals a Metabolic Shift after Surgical Resection of Non-Small Cell Lung Cancer.

BACKGROUND: Lung cancer can be detected by measuring the patient's plasma metabolomic profile using nuclear magnetic resonance (NMR) spectroscopy. This NMR-based plasma metabolomic profile is patient-specific and represents a snapshot of the patient's metabolite concentrations. The onset of non-small cell lung cancer (NSCLC) causes a change in the metabolite profile. However, the level of metabolic changes after complete NSCLC removal is currently unknown. PATIENTS AND METHODS: Fasted pre- and postoperative plasma samples of 74 patients diagnosed with resectable stage I-IIIA NSCLC were analyzed using 1H-NMR spectroscopy. NMR spectra (s = 222) representing two preoperative and one postoperative plasma metabolite profile at three months after surgical resection were obtained for all patients. In total, 228 predictors, i.e., 228 variables representing plasma metabolite concentrations, were extracted from each NMR spectrum. Two types of supervised multivariate discriminant analyses were used to train classifiers presenting a strong differentiation between the pre- and postoperative plasma metabolite profiles. The validation of these trained classification models was obtained by using an independent dataset. RESULTS: A trained multivariate discriminant classification model shows a strong differentiation between the pre- and postoperative NSCLC profiles with a specificity of 96% (95% CI [86-100]) and a sensitivity of 92% (95% CI [81-98]). Validation of this model results in an excellent predictive accuracy of 90% (95% CI [77-97]) and an AUC value of 0.97 (95% CI [0.93-1]). The validation of a second trained model using an additional preoperative control sample dataset confirms the separation of the pre- and postoperative profiles with a predictive accuracy of 93% (95% CI [82-99]) and an AUC value of 0.97 (95% CI [0.93-1]). Metabolite analysis reveals significantly increased lactate, cysteine, asparagine and decreased acetate levels in the postoperative plasma metabolite profile. CONCLUSIONS: The results of this paper demonstrate that surgical removal of NSCLC generates a detectable metabolic shift in blood plasma. The observed metabolic shift indicates that the NSCLC metabolite profile is determined by the tumor's presence rather than donor-specific features. Furthermore, the ability to detect the metabolic difference before and after surgical tumor resection strongly supports the prospect that NMR-generated metabolite profiles via blood samples advance towards early detection of NSCLC recurrence.

Unraveling the Rewired Metabolism in Lung Cancer Using Quantitative NMR Metabolomics.

Lung cancer cells are well documented to rewire their metabolism and energy production networks to enable proliferation and survival in a nutrient-poor and hypoxic environment. Although metabolite profiling of blood plasma and tissue is still emerging in omics approaches, several techniques have shown potential in cancer diagnosis. In this paper, the authors describe the alterations in the metabolic phenotype of lung cancer patients. In addition, we focus on the metabolic cooperation between tumor cells and healthy tissue. Furthermore, the authors discuss how metabolomics could improve the management of lung cancer patients.

Staphylococcus aureus endocarditis: distinct mechanisms of bacterial adhesion to damaged and inflamed heart valves.

AIMS: The pathogenesis of endocarditis is not well understood resulting in unsuccessful attempts at prevention. Clinical observations suggest that Staphylococcus aureus infects either damaged or inflamed heart valves. Using a newly developed endocarditis mouse model, we therefore studied the initial adhesion of S. aureus in both risk states. METHODS AND RESULTS: Using 3D confocal microscopy, we examined the adhesion of fluorescent S. aureus to murine aortic valves. To mimic different risk states we either damaged the valves with a surgically placed catheter or simulated valve inflammation by local endothelium activation. We used von Willebrand factor (VWF) gene-deficient mice, induced platelet and fibrinogen depletion and used several S. aureus mutant strains to investigate the contribution of both host and bacterial factors in early bacterial adhesion. Both cardiac valve damage and inflammation predisposed to endocarditis, but by distinct mechanisms. Following valve damage, S. aureus adhered directly to VWF and fibrin, deposited on the damaged valve. This was mediated by Sortase A-dependent adhesins such as VWF-binding protein and Clumping factor A. Platelets did not contribute. In contrast, upon cardiac valve inflammation, widespread endothelial activation led to endothelial cell-bound VWF release. This recruited large amounts of platelets, capturing S. aureus to the valve surface. Here, neither fibrinogen, nor Sortase A were essential. CONCLUSION: Cardiac valve damage and inflammation predispose to S. aureus endocarditis via distinct mechanisms. These findings may have important implications for the development of new preventive strategies, as some interventions might be effective in one risk state, but not in the other.

Synthetic glycopolymers and natural fucoidans cause human platelet aggregation via PEAR1 and GPIbα.

Fucoidans are sulfated fucose-based polysaccharides that activate platelets and have pro- and anticoagulant effects; thus, they may have therapeutic value. In the present study, we show that 2 synthetic sulfated α-l-fucoside-pendant glycopolymers (with average monomeric units of 13 and 329) and natural fucoidans activate human platelets through a Src- and phosphatidylinositol 3-kinase (PI3K)-dependent and Syk-independent signaling cascade downstream of the platelet endothelial aggregation receptor 1 (PEAR1). Synthetic glycopolymers and natural fucoidan stimulate marked phosphorylation of PEAR1 and Akt, but not Syk. Platelet aggregation and Akt phosphorylation induced by natural fucoidan and synthetic glycopolymers are blocked by a monoclonal antibody to PEAR1. Direct binding of sulfated glycopolymers to epidermal like growth factor (EGF)-like repeat 13 of PEAR1 was shown by avidity-based extracellular protein interaction screen technology. In contrast, synthetic glycopolymers and natural fucoidans activate mouse platelets through a Src- and Syk-dependent pathway regulated by C-type lectin-like receptor 2 (CLEC-2) with only a minor role for PEAR1. Mouse platelets lacking the extracellular domain of GPIbα and human platelets treated with GPIbα-blocking antibodies display a reduced aggregation response to synthetic glycopolymers. We found that synthetic sulfated glycopolymers bind directly to GPIbα, substantiating that GPIbα facilitates the interaction of synthetic glycopolymers with CLEC-2 or PEAR1. Our results establish PEAR1 as the major signaling receptor for natural fucose-based polysaccharides and synthetic glycopolymers in human, but not in mouse, platelets. Sulfated α-l-fucoside-pendant glycopolymers are unique tools for further investigation of the physiological role of PEAR1 in platelets and beyond.

Absence of Pear1 does not affect murine platelet function in vivo.

BACKGROUND: Platelet Endothelial Aggregation Receptor-1 (PEAR1) is a transmembrane platelet receptor that amplifies the activation of the platelet fibrinogen receptor (αIIbß3) during platelet aggregation. In man, Pear1 polymorphisms are associated with changes in platelet aggregability. In this report, we characterized Pear1 expression and function in murine platelets. METHODS: Pear1 phosphorylation and signaling, platelet aggregation, α-degranulation and clot retraction were studied in WT and Pear1-/- platelets. The function of Pear1 in haemostasis and thrombosis was studied in a mouse tail vein bleeding and ferric chloride-induced mesenteric thrombosis model. RESULTS: Mature murine platelets express Pear1 on their membrane and clustering of Pear1 by anti-Pear1 antibodies triggered platelet aggregation. Pear1 was weakly phosphorylated during collagen-induced murine platelet aggregation and was translocated to the cytoskeleton. Absence of murine Pear1 impaired dextran sulfate-induced platelet aggregation, but did not impact collagen-, AYPGK and ADP-induced platelet aggregation, coupled to a lower Pear1 expression in murine than in human platelets and to weaker Pear1-mediated downstream signaling. Neither clot retraction nor α-degranulation was affected in Pear1-/- mice. Likewise, in vivo tests like the tail vein bleeding time and thrombus formation in mesenteric veins were similar in WT and Pear1-/- mice. CONCLUSION: Murine platelet Pear1 shares a number of characteristics with human platelet PEAR1. Nevertheless, murine Pear1 contributes less to platelet function as does human PEAR1 and does not overtly impact haemostasis and thrombosis in mice.

Shear-Resistant Binding to von Willebrand Factor Allows Staphylococcus lugdunensis to Adhere to the Cardiac Valves and Initiate Endocarditis.

BACKGROUND: Staphylococcus lugdunensis is an emerging cause of endocarditis. To cause endovascular infections, S. lugdunensis requires mechanisms to overcome shear stress. We investigated whether platelets and von Willebrand factor (VWF) mediate bacterial adhesion to the vessel wall and the cardiac valves under flow. METHODS: S. lugdunensis binding to VWF, collagen, and endothelial cells was studied in a parallel flow chamber in the absence and presence of platelets. In vivo adhesion of S. lugdunensis was evaluated in a mouse microvasculature perfusion model and a new mouse model of endocarditis. RESULTS: Contrary to other coagulase-negative staphylococci, S. lugdunensis bound to VWF under flow, thus enabling its adhesion to endothelial cells and to the subendothelial matrix. In inflamed vessels of the mesenteric circulation, VWF recruited S. lugdunensis to the vessel wall. In a novel endocarditis mouse model, local inflammation and the resulting release of VWF enabled S. lugdunensis to bind and colonize the heart valves. CONCLUSIONS: S. lugdunensis binds directly to VWF, which proved to be vital for withstanding shear forces and for its adhesion to the vessel wall and cardiac valves. This mechanism explains why S. lugdunensis causes more-aggressive infections, including endocarditis, compared with other coagulase-negative staphylococci.

Dextran sulfate triggers platelet aggregation via direct activation of PEAR1.

UNLABELLED: Dextran sulfate (DxS; Mr 500 kD) induces fibrinogen receptor (αIIbß3) activation via CLEC-2/Syk signaling and via a Syk-independent SFK/PI3K/Akt-dependent tyrosine kinase pathway in human and murine platelets. The platelet surface receptor, responsible for the DxS-induced Syk-independent Akt-activation, has hitherto not been identified. We found that DxS elicited a concentration-dependent aggregation of human platelets resulting from direct PEAR1 activation by DxS. Blocking the PEAR1 receptor, in combination with a selective Syk-inhibitor, completely abrogated the DxS-driven platelet aggregation. The DxS-induced Syk-phosphorylation was not affected in Pear1(-/-) platelets, but Akt-phosphorylation was largely abolished. As a result, the aggregation of Pear1(-/-) platelets was reduced and reversible, i.e. aggregates were less stable compared to wild-type platelet aggregates. Moreover, DxS-induced Pear1(-/-) platelet aggregation was fully abrogated by Syk inhibition, indicating that the remaining platelet aggregation of Pear1(-/-) platelets was Syk dependent. Hence, the Pear1/c-Src/PI3K/Akt- and CLEC-2/Syk-signaling pathways are independently and additively activated during platelet aggregation by DxS. CONCLUSION: The DxS-induced aggregation of human and murine platelets is the result of activation of PI3K/Akt through direct PEAR1 phosphorylation and parallel Syk-signaling through CLEC-2.

Platelet endothelial aggregation receptor-1: a novel modifier of neoangiogenesis.

AIMS: Platelet endothelial aggregation receptor-1 (PEAR1) is a cell membrane protein, expressed on platelets and endothelial cells (ECs). PEAR1 sustains αIIbß3 activation in aggregating platelets and attenuates megakaryopoiesis via controlling the degree of Akt phosphorylation. Its role in EC biology is unknown. The aim of this study was to determine the expression of PEAR1 in the human endothelium of various tissues and to investigate its role in ECs in vitro and in angiogenesis, using Pear1(-/-) mice. METHODS AND RESULTS: PEAR1 is present on the membrane and on filo- and lamellipodia of human cultured ECs, and its expression coincides with CD31 in various tissues. PEAR1 expression is variable in ECs of different origin. Lentiviral knockdown of PEAR1 in cultured ECs doubled EC proliferation and significantly stimulated EC migration, in turn enhancing in vitro tube formation on matrigel through the Akt/PTEN-dependent p21/CDC2 pathway. Even when physiological blood vessel formation was unaffected in Pear1(-/-) mice, neoangiogenesis in these mice was significantly increased both in a hind limb ischaemia ligation model [4.7-fold increase in capillary density in the ligated limb of Pear1(-/-) mice compared with ligated limbs in wild-type (WT) mice] and in a skin wound-healing model, resulting in a two-fold faster wound closure in Pear1(-/-) mice compared with WT littermates. CONCLUSION: We established an inverse correlation between endothelial PEAR1 expression and vascular assembly both in vitro and in vivo. These findings identify PEAR1 as a novel modifier of neoangiogenesis.

Reversal of jaundice in two patients with inoperable cholangiocarcinoma treated with Cisplatin and gemcitabine combination.

Two patients are presented with severe jaundice, due to inoperable cholangiocarcinoma. The chemotherapeutic approach in patients with severe jaundice is discussed. Many schedules of chemotherapy were developed in this tumor type with normal serum bilirubin. We report here the first successful use of cisplatin and gemcitabine combination chemotherapy in these patients. Tolerability was good and liver function tests gradually improved.