Leukocyte-endothelial Interactions Research Articles

Protective effects of Ruscus extract in combination with ascorbic acid and hesperidine methylchalcone on increased leukocyte-endothelial interaction and macromolecular permeability induced by ischemia reperfusion injury.

Despite the well-recognized effectiveness of Ruscus aculetus extract combined or not with ascorbic acid (AA) and hesperidine methyl chalcone (HMC) on ischemia reperfusion (I/R) injury protection, little is known about the contribution of each constituent for this effect. To investigate the effects of AA and HMC combined or not with Ruscus extract on increased macromolecular permeability and leukocyte-endothelium interaction induced by I/R injury. Hamsters were treated daily during two weeks with filtered water (placebo), AA (33, 100 and 300 mg/kg/day) and HMC (50, 150 and 450 mg/kg/day) combined or not with Ruscus extract (50, 150 and 450 mg/kg/day). On the day of experiment, the cheek pouch microcirculation underwent 30 min of ischemia, and the number of rolling and adherent leukocytes and leaky sites were evaluated before ischemia and during 45 min of reperfusion. Ruscus extract combined with AA and HMC (Ruscus extract mixture) significantly prevented post-ischemic increase in leukocyte rolling and adhesion and macromolecular permeability compared to placebo and these effects were more prominent than AA and HMC alone on leukocyte adhesion and macromolecular leakage. Ruscus extract mixture were more effective than its isolated constituents in protect the hamster cheek pouch microcirculation against I/R injury.

Gingival inflammation and leukocyte-endothelium cell interactions in women with polycystic ovary syndrome.

Given the link between chronic inflammation and periodontal pathologies and increased cardiovascular risk, this study aims to investigate if gingivitis exacerbates the inflammatory response and subclinical atherosclerotic markers in women with polycystic ovary syndrome (PCOS). For this case-control study, women were assigned to three groups: two PCOS groups (with and without gingivitis) and a control group. Anthropometric and biochemical variables were determined, along with periodontal parameters (probing pocket depth [PPD], clinical attachment level [CAL], bleeding on probing [BOP], plaque index, calculus index, and tooth loss), systemic and neutrophil inflammatory markers (tumor necrosis factor alpha [TNFα], C-reactive protein [CRP], and c-Jun N-terminal kinase [JNK]), systemic oxidative stress mediators (myeloperoxidase [MPO] and glutathione), soluble cellular adhesion molecules, and neutrophil-endothelium cell interactions (rolling flux, velocity, and adhesion). Of 104 women recruited, 68 had PCOS, 24 of whom presented gingivitis, and 36 were controls. PCOS patients presented altered sexual hormone, lipid, and carbohydrate profiles. Levels of systemic inflammatory markers, MPO, and soluble platelet selectin (sP-selectin) were higher, and glutathione levels were lower in PCOS patients. BOP, plaque, and calculus index values were higher in PCOS patients with gingivitis. Neutrophils from PCOS patients showed increased JNK and decreased adhesion under flow conditions, with reduced rolling velocity and increased rolling flux and cellular adhesion, all of which were more pronounced in those with gingivitis. BOP was independently associated with rolling velocity, rolling flux, and cellular adhesion. Neutrophils of PCOS patients with gingivitis exhibit hyperactivity, promoting interaction with the endothelium and potentially contributing to atherosclerotic disease. Currently, there is a high prevalence of diseases that affect tooth-supporting tissues (periodontal diseases) and negatively influence the oral health and quality of life of the adult population. These pathologies lead to movement of the teeth and impairment of chewing function, eventually resulting in the loss of teeth. In recent years, the concept of periodontal medicine has arisen and consists of studying how periodontal diseases can influence our general inflammatory system and how systemic inflammatory pathologies can affect our oral health. In the present study, we evaluate a group of women with polycystic ovary syndrome (PCOS), a condition characterized by alterations of sex hormones and lipid profile and weight gain (body mass index). Our results show a high prevalence of gum inflammation among women with PCOS, which affects the interaction of their leukocytes and endothelial cells. The leukocytes of these women are hyper-responsive, presenting greater endothelial adhesion, lower flow velocity and enhanced rolling compared to those in a PCOS group without gum inflammation or controls. This study has generated a new line of research to analyze how neutrophils from patients with gingivitis exhibit hyperactivity, which promotes their interaction with the endothelium, thus contributing to the development of atherosclerotic disease.

Endothelium Piezo1 deletion alleviates experimental varicose veins by attenuating perivenous inflammation.

Previous large-scale genetic studies have prioritized the causal genes piezo type mechanosensitive ion channel component 1 (PIEZO1) and castor zinc finger 1 (CASZ1) associated with varicose veins (VVs). This study aims to evaluate their roles in both clinical and experimental VVs. In this study, we investigated abundance of PIEZO1 and CASZ1 in both varicose and normal veins from the same patients. Yoda1 (a selective PIEZO1 agonist, 2.6mg/kg/day) or vehicle was administered intraperitoneally for 3weeks to evaluate the effect of PIEZO1 activation on experimental VVs. Subsequently, endothelial Piezo1 deletion mice (Piezo1iΔEC mice) were generated to explored the role of endothelial PIEZO1 on VVs. Laser speckle imaging, flow cytometry, cell tracing with Evans blue or rhodamine-6G, and histopathological staining were utilized to evaluate the pathophysiology of VVs. Our results showed that mRNA expression of PIEZO1, but not CASZ1, was abundant and increased in clinical VVs. The Piezo1tP1-td mice revealed endothelium-specific expression of PIEZO1 in mice veins. By establishing iliac vein ligation-induced VVs in mice, Yoda1 exacerbated experimental VVs with increased inflammatory cell infiltration. Subsequently, endothelial Piezo1 deletion (Piezo1iΔEC mice) alleviated experimental VVs and vascular remodeling by directly reducing vascular permeability and leukocyte-endothelium interactions compared to the control (Piezo1fl/fl mice). PIEZO1 is highly expressed in clinical VVs, meanwhile, activation or inhibition of PIEZO1 exerts a remarkable effect on experimental VVs. Furthermore, Piezo1 may constitute a potential therapeutic approach for the medical treatment of VVs.

Molecular circadian clock disruption in the leukocytes of individuals with type 2 diabetes and overweight, and its relationship with leukocyte–endothelial interactions

Aims/hypothesisAlterations in circadian rhythms increase the likelihood of developing type 2 diabetes and CVD. Circadian rhythms are controlled by several core clock genes, which are expressed in nearly every cell, including immune cells. Immune cells are key players in the pathophysiology of type 2 diabetes, and participate in the atherosclerotic process that underlies cardiovascular risk in these patients. The role of the core clock in the leukocytes of people with type 2 diabetes and the inflammatory process associated with it are unknown. We aimed to evaluate whether the molecular clock system is impaired in the leukocytes of type 2 diabetes patients and to explore the mechanism by which this alteration leads to an increased cardiovascular risk in this population.MethodsThis is an observational cross-sectional study performed in 25 participants with type 2 diabetes and 28 healthy control participants. Clinical and biochemical parameters were obtained. Peripheral blood leukocytes were isolated using magnetic bead technology. RNA and protein lysates were obtained to assess clock-related gene transcript and protein levels using real-time PCR and western blot, respectively. Luminex XMAP technology was used to assess levels of inflammatory markers. Leukocyte–endothelial interaction assays were performed by perfusing participants’ leukocytes or THP-1 cells (with/without CLK8) over a HUVEC monolayer in a parallel flow chamber using a dynamic adhesion system.ResultsParticipants with type 2 diabetes showed increased BMAL1 and NR1D1 mRNA levels and decreased protein levels of circadian locomotor output cycles kaput (CLOCK), cryptochrome 1 (CRY1), phosphorylated basic helix-loop-helix ARNT like 1 (p-BMAL1) and period circadian protein homologue 2 (PER2). Correlation studies revealed that these alterations in clock proteins were negatively associated with glucose, HbA1c, insulin and HOMA-IR levels and leukocyte cell counts. The leukocyte rolling velocity was reduced and rolling flux and adhesion were enhanced in individuals with type 2 diabetes compared with healthy participants. Interestingly, inhibition of CLOCK/BMAL1 activity in leukocytes using the CLOCK inhibitor CLK8 mimicked the effects of type 2 diabetes on leukocyte–endothelial interactions.Conclusions/interpretationOur study demonstrates alterations in the molecular clock system in leukocytes of individuals with type 2 diabetes, manifested in increased mRNA levels and decreased protein levels of the core clock machinery. These alterations correlated with the impaired metabolic and proinflammatory profile of the participants with type 2 diabetes. Our findings support a causal role for decreased CLOCK/BMAL1 activity in the increased level of leukocyte–endothelial interactions. Overall, our data suggest that alterations in core clock proteins accelerate the inflammatory process, which may ultimately precipitate the onset of CVD in patients with type 2 diabetes.Graphical

Nonlinear association of fibrinogen levels with functional prognosis in patients with acute ischemic stroke: a prospective cohort study

ObjectiveFibrinogen, essential in primary hemostasis, platelet aggregation, and leukocyte-endothelial interactions, is also associated with a heightened risk of acute ischemic stroke (AIS). However, its influence on AIS patient outcomes is unclear. This study examines the correlation between fibrinogen levels and the risk of unfavorable outcomes three months post-AIS.MethodsThis is a secondary analysis of a prospective cohort study conducted in Korea. The sample consisted of 1851 AIS patients who received treatment at a Korean hospital between January 2010 and December 2016. Statistical models were established to understand the relationship between fibrinogen levels(mg/dL) and unfavorable outcomes(mRs ≥ 3), including logistic regression models, Generalized Additive Models (GAM), and smooth curve fitting (penalized splines). The log-likelihood ratio test has been utilized to evaluate the best fit. To ensure the robustness of the results, sensitivity analyses were conducted by reanalyzing the relationship after excluding participants with TG > 200 mg/dl and BMI > 25 kg/m2. Subgroup analyses were also performed to assess whether influencing factors modify the association between fibrinogen levels and unfavorable outcomes.ResultsAfter adjusting for multiple covariates including age, BMI, sex, LDL-c, TG, HGB, HDL-c, BUN, FPG, ALB, PLT, AF, hypertension, smoking, DM, mRs score at admission, the binary logistic regression model demonstrated revealed a significant positive association between fibrinogen levels and the risk of unfavorable outcomes in AIS patients (OR = 1.215, 95% CI: 1.032–1.429, p = 0.019). Sensitivity analyses supported these findings, with similar ORs observed in subsets of patients with TG < 200 mg/dL (OR = 1.221, 95% CI: 1.036–1.440) and BMI < 25 kg/m2 (OR = 1.259, 95% CI: 1.051–1.509). Additionally, the relationship between fibrinogen levels and outcomes was nonlinear, with a critical threshold of 2.74 g/L. Below the inflection point, the OR for unfavorable outcomes was 0.666 ((95% CI: 0.360, 1.233, p = 0.196), whereas above it, the OR increased to 1.374 (95% CI: 1.138, 1.659).ConclusionsThis study has provided evidence of a positive and nonlinear correlation between fibrinogen levels and 3-month poor functional outcomes in patients with AIS. When fibrinogen levels exceeded 2.74 g/L, a significant and positive association was observed with the risk of poor outcomes. This study provides a further reference for optimizing rehabilitation exercises and facilitating clinical counseling in patients with acute ischemic stroke.

Benzydamine hydrochloride: an overview on a well-established drug with news in mechanisms of action

Pain and inflammation are the consequences of sore throat, dental and oral procedures, infections, ulcers and head and neck chemotherapy/radiotherapy, and their management is of fundamental importance to avoid distress in patients. Benzydamine hydrochloride (HCl) is a topical indolic nonsteroidal anti-inflammatory drug, endowed with analgesic and anesthetic activity, and with antimicrobial (including both gram-positive and gram-negative bacteria) and antifungal properties (targeting Candida albicans and non-albicans strains), used in odontostomatology, otorhinolaryngology, and gynecology for its properties. This molecule has a lipophilic nature, showing high affinity with cell membranes and exhibiting membrane stabilization properties, resulting in local anesthesia, an effect related also to the interaction of the drug with cationic channels. In addition, benzydamine HCl is able to inhibit the production of pro-inflammatory cytokines, with consequent analgesia. Moreover, benzydamine HCl is able to inhibit leukocyte-endothelial interactions and platelet aggregation. Unlike other non-steroidal anti-inflammatory drugs, benzydamine HCl does not inhibit cyclooxygenase or lipoxygenase. Here we review the most updated clinical data available on benzydamine HCl local application as spray, mouthwash or gargling and evidence of its effectiveness in inflammatory and/or septic conditions in the otorhinolaryngology and odontostomatology settings, with particular reference to sore throat, oral inflammation, dental plaque, tonsillitis/tonsillectomy and chemo- or radiotherapy-induced oral mucositis. Novel formulations for oral administration of benzydamine HCl are also reviewed, including in situ gelling formulations to be sprayed onto the damaged oral mucosa. Finally, novel data on the potential role of benzydamine HCl in nociceptor excitability are introduced.

Understanding Local Reactions Induced by Bothrops jararaca Venom: The Role of Inflammatory Mediators in Leukocyte-Endothelium Interactions.

In recent years, extensive research has delved into the pathophysiology of local reactions triggered by Bothrops snake venoms. Even though antivenom works well at reducing death and systemic effects, it is still not very effective in treating local reactions because it cannot counteract damage that has already been triggered. This limitation might be attributed to certain molecules that amplify the venom-induced innate response. While evidence suggests endogenous mediators at the venom site play a role in this envenomation, in Brazil, the concurrent use of anti-inflammatory agents or other drugs alongside antivenom remains uncommon. This study evaluated the pharmacological mediation of alterations in leukocyte-endothelium interactions following the experimental envenomation of mice with Bothrops jararaca venom, the main culprit of snake-related accidents in Southeast Brazil. We treated envenomed mice with inhibitors of different pharmacological pathways and observed the cremaster muscle microcirculation with intravital microscopy. We found that eicosanoids related to cyclooxygenase pathways and nitric oxide significantly contributed to B. jararaca venom-induced alterations in leukocyte-endothelium interactions. Conversely, lipoxygenase-mediated eicosanoids, histamine, and serotonin had minimal participation. Notably, dexamethasone and antivenom treatment diminished B. jararaca venom-induced alterations in leukocyte-endothelium interactions. The limited efficacy of the antivenom in managing Bothrops venom-induced local reactions emphasizes the critical need for supplementary treatments to enhance therapeutic outcomes.

A three-dimensional vessel-on-chip model to study Puumala orthohantavirus pathogenesis.

Puumala orthohantavirus (PUUV) infection in humans can result in hemorrhagic fever with renal syndrome. Endothelial cells (ECs) are primarily infected with increased vascular permeability as a central aspect of pathogenesis. Historically, most studies included ECs cultured under static two-dimensional (2D) conditions, thereby not recapitulating the physiological environment due to their lack of flow and inherent pro-inflammatory state. Here, we present a high-throughput model for culturing primary human umbilical vein ECs in 3D vessels-on-chip in which we compared host responses of these ECs to those of static 2D-cultured ECs on a transcriptional level. The phenotype of ECs in vessels-on-chip more closely resembled the in vivo situation due to higher similarity in expression of genes encoding described markers for disease severity and coagulopathy, including IDO1, LGALS3BP, IL6 and PLAT, and more diverse endothelial-leukocyte interactions in the context of PUUV infection. In these vessels-on-chip, PUUV infection did not directly increase vascular permeability, but increased monocyte adhesion. This platform can be used for studying pathogenesis and assessment of possible therapeutics for other endotheliotropic viruses even in high biocontainment facilities.

Caspase-1 As a Therapeutic Target in Intravascular Hemolysis-Induced Microvascular Inflammation and Occlusive Processes

Hemolytic anemias, such as sickle cell disease (SCD), are a group of acute and acquired conditions characterized by the accelerated destruction of red blood cells (RBC). Intravascular hemolysis (IVH), or RBC lysis within the bloodstream, incurs the release of damage-associated molecular patterns (DAMPs), trigging cell activation and immune responses. Caspase-1 (Casp-1), a protease enzyme, plays a critical role during inflammatory processes by initiating programed cell death and promoting the cleavage of pro-interleukin (IL)-1β into its active form, IL-1β, through inflammasome assembly. Here, we aimed to elucidate the complex mechanisms involved in IVH-induced inflammation, leukocyte-endothelium interactions, and microvascular dynamics. Acute IVH was induced in C57BL/6 mice (HEM) by the injection of sterile water (i.v., 150 µl), and control mice received i.v. saline (CON) (n=3-8 per group). Intravital microscopy was performed at 15 min post IVH induction on the cremaster muscle of mice to quantify venular leukocyte (WBC) rolling and adhesion, and non-invasive laser Doppler flowmetry (LDF) measured blood perfusion in the murine pelvis microvasculature. Blood samples were collected at 1-hour post-IVH for ELISA and flow cytometry analyses. Immortalized human endothelial cells (HUVEC; n=7 per group) were stimulated with heme or S100A8 for 3 hours. HEM mice demonstrated significantly increased plasma heme (P&amp;lt;0.0001) and cell-free hemoglobin (P&amp;lt;0.001), in association with significantly decreased plasma haptoglobin (P&amp;lt;0.05), compared to CON mice, thereby confirming the occurrence of IVH. Furthermore, HEM mice exhibited significantly increased plasma concentrations of the S100A8 alarmin (P&amp;lt;0.001) and IL1-β (P&amp;lt;0.001), as well as augmentations (P&amp;lt;0.001) in plasma TNF-ɑ and IL-6 levels. Flow cytometry was used to measure active Casp-1 in neutrophils and monocytes of mice using the FAM-FLICA probe. FLICA staining was significantly higher in the neutrophils (P&amp;lt;0.05) and monocytes (P&amp;lt;0.05) of HEM mice, compared to CON mice, implying Casp-1 activation in these cell subsets. WBC-endothelium interactions are a hallmark of vaso-occlusion in SCD. HEM mice exhibited elevated venular WBC rolling and adhesion to the endothelium, compared to CON mice (P&amp;lt;0.001), as previously shown (Almeida et al., 2015; PMID: 26019278). In addition, IVH significantly reduced the velocity of microvascular blood flow in mice (P&amp;lt;0.001), and impaired perfusion (P&amp;lt;0.001). To address the role of IVH-induced Casp-1 activation in microvascular dynamics, mice received i.p. administrations of the Casp-1 inhibitor, YVAD, at 1 hour prior to induction of IVH, or not, and were subjected to intravital microscopy or LDF. Interestingly, the inhibition of Casp-1 significantly abrogated IVH-induced WBC rolling (P&amp;lt;0.01) and adhesion to vessel walls (P&amp;lt;0.05) in HEM mice and significantly improved microvascular blood perfusion and flow velocity (P&amp;lt;0.05), suggesting a role for Casp-1 activation in the WBC-endothelium and occlusive interactions observed (See Figure). We then evaluated how heme and S100A8 may induce endothelial cell activation, as these DAMPs were found elevated in the plasma of HEM mice. As expected, compared to unstimulated HUVEC, heme induced endothelial cell activation in vitro, as shown by higher expressions of ICAM-1 (P&amp;lt;0.05), VCAM-1 (P&amp;lt;0.01) and E-selectin (P&amp;lt;0.01), and increased Casp-1 activity (P&amp;lt;0.01). In turn, S100A8 alone significantly elevated ICAM-1 (P&amp;lt;0.05) and E-selectin (P&amp;lt;0.01) expressions on HUVEC, as well as IL-1β release (P&amp;lt;0.001), however no significant increase in Casp-1 activity was observed. HUVEC, when pre-treated with YVAD, displayed a significant reduction in S100A8-induced E-selectin expression (P&amp;lt;0.05), but neither ICAM-1 nor VCAM-1 expression were significantly decreased. In contrast, no changes in the expressions of these adhesion molecules were observed in heme-stimulated cells after YVAD treatment. Taken together, these findings suggest that targeting caspase-1 activation and its associated pathways may represent a potential therapeutic intervention to mitigate the adverse inflammatory and microvascular effects of IVH, a disease mechanism that occurs in severe hemolytic anemias such as SCD.

The Role of P-Selectin in Microvascular Hemodynamics and Cerebral Brain Volumes in Aging Sickle Cell Mice

Cerebral vasculopathy has been linked to the development of cognitive impairment in sickle cell disease (SCD). We have previously demonstrated that 13-month-old sickle cell mice recapitulate features of cerebral vasculopathy such as tortuous vessels, microthrombi, and hypoperfusion seen in adults with SCD. Histologically, we also showed these mice have increased cerebral microvascular deposition of P-selectin and more frequent and larger microinfarcts compared to matched controls. We further showed that these mice developed evidence of cognitive deficit compared to matched controls. Based on these observations, we hypothesized P-selectin may play a critical role in development of cerebral micro vasculopathy and downstream pathologic sequalae such as microinfarcts by enhancing leukocyte-endothelial interactions. Furthermore, abundant evidence from non-sickle mice shows that microinfarcts can exacerbate small vessel changes including gray matter volume loss. Building on our prior work, in this study, we examined the effect of P-selectin deficiency on cerebral microvascular hemodynamics and leukocyte-endothelial interaction and well as changes in cortical and subcortical gray matter volume in aged sickle mice. Male, P-selectin knockout (Psel KO) or intact (Psel WT) chimeric mice were generated by transplanting control (AA) or sickle (SS) bone marrow into P-selectin knockout (Psel -/-) or C57BL/6 (B6) recipients. To assess the impact of vasculopathy and brain gray matter volume changes longitudinally, male mice were assessed at 12-, 14- or 16-month post-transplant. Hemodynamics (mean velocity, red blood cell (RBC) flux, white blood cell stalls in capillaries as well as venules) were obtained from line-scan images acquired using in-vivo two-photon microscopy, using custom and validated MATLAB scripts. Gray matter volumes in 26 cortical and subcortical brain regions with relevance to cognitive function, were derived from parcellation of T2-weighted magnetic resonance imaging after non-linear registration to Allen brain atlas T1 anatomical space. Parcellation was accomplished by registering the Paxinos atlas to the mouse T2 now in Allen space. Brain volume analyses was accomplished using Analyze 12 software. After the completion of in-vivo studies, brains were extracted for immunohistochemistry analysis. Statistical analysis was performed using two-way ANOVA. The breakdown of the mice included in this study are; 14 B6 AA, 12 B6 SS, 12 Psel KO AA and 13 Psel KO SS. Given the high attrition rate in older mice, data from 12-, 14- and 16-month-old cohorts were combined. Mean age of B6 AA cohort was 13.1 months, 12.8 months for B6 SS, 13. 9 months for Psel KO AA and 13.6 months for Psel KO SS mice and were not statistically different. Psel KO sickle mice had a significantly lower mean capillary RBC velocity (1.733 mm/s vs 4.717 mm/s, p &amp;lt; 0.01) compared to Psel WT SS mice. In addition, Psel KO SS mice had relatively smaller (more normal) capillary diameter compared to Psel WT SS mice (6.248 um vs 8.613 um, p &amp;lt; 0.001). Interestingly, there was no statistically significant difference in RBC flux between Psel KO SS and Psel WT SS mice, however Psel KO SS mice show a lower red blood cell flux similar to that seen in Psel WT AA mice ( Figure 1). Of the 26 brain regions that were assessed, Psel KO SS mice had larger measured gray matter volume in the frontal association cortex (3.01 ± 0.77 vs 3.66± 0.33 mm 3, p= 0.0083), prelimbic cortex (1.72 ± 0.27 vs 1.95 ± 0.17 mm 3, p=0.0079), hippocampus (17.67 ± 1.56 vs 16.21± 1.97 mm 3, p=0.01)( Figure 1) including other regions such as lateral (2.12 ± 0.19 vs 1.88 ± 0.31 vs mm 3 p=0.0096) medial (1.84± 0.16 vs 1.64 ± 0.26 mm 3, p=0.01), and ventral orbital cortex( 1.95± 0.17 vs1.72 ± 0.27 mm 3, p=0.01) and dorsolateral olfactory tract (1.46 6± 0.13 vs 1.31 ± 0.20 mm 3, p=0.023 compared to the Psel WT SS mice (data not shown). In conclusion, non-hematopoetic P-selectin deficiency improves cerebral vasculopathy as demonstrated by normalization of hemodynamics in sickle mice. We also show that Psel KO SS mice had larger brain gray matter volume in regions involved in cognitive function. Additional studies are needed to identify the underlying mechanism of improvement in brain gray matter volume as well as whether P-selectin could be potential target for reducing SCD associated neurological complications.

Miniaturized microscope for non-invasive imaging of leukocyte-endothelial interaction in human microcirculation

We present a miniature oblique back-illumination microscope (mOBM) for imaging the microcirculation of human oral mucosa, enabling real-time, label-free phase contrast imaging of individual leukocytes circulating in the bloodstream, as well as their rolling and adhesion on vascular walls—the initial steps in leukocyte recruitment that is a hallmark of inflammation. Using the mOBM system, we studied the leukocyte-endothelial interactions in healthy and locally inflamed tissue and observed drastic changes in leukocyte movement (velocity and displacement profile). Our findings suggest that real-time imaging of leukocyte dynamics can provide new diagnostic insights (assessment of inflammation, temporal progression of disease, evaluation of therapeutic response, etc.) that are not available using conventional static parameters such as cell number and morphology.

Alpha-1 antitrypsin inhibits fractalkine-mediated monocyte-lung endothelial cell interactions.

Chronic obstructive pulmonary disease (COPD) is characterized by nonresolving inflammation fueled by breach in the endothelial barrier and leukocyte recruitment into the airspaces. Among the ligand-receptor axes that control leukocyte recruitment, the full-length fractalkine ligand (CX3CL1)-receptor (CX3CR1) ensures homeostatic endothelial-leukocyte interactions. Cigarette smoke (CS) exposure and respiratory pathogens increase expression of endothelial sheddases, such as a-disintegrin-and-metalloproteinase-domain 17 (ADAM17, TACE), inhibited by the anti-protease α-1 antitrypsin (AAT). In the systemic endothelium, TACE cleaves CX3CL1 to release soluble CX3CL1 (sCX3CL1). During CS exposure, it is not known whether AAT inhibits sCX3CL1 shedding and CX3CR1+ leukocyte transendothelial migration across lung microvasculature. We investigated the mechanism of sCX3CL1 shedding, its role in endothelial-monocyte interactions, and AAT effect on these interactions during acute inflammation. We used two, CS and lipopolysaccharide (LPS) models of acute inflammation in transgenic Cx3cr1gfp/gfp mice and primary human endothelial cells and monocytes to study sCX3CL1-mediated CX3CR1+ monocyte adhesion and migration. We measured sCX3CL1 levels in plasma and bronchoalveolar lavage (BALF) of individuals with COPD. Both sCX3CL1 shedding and CX3CR1+ monocytes transendothelial migration were triggered by LPS and CS exposure in mice, and were significantly attenuated by AAT. The inhibition of monocyte-endothelial adhesion and migration by AAT was TACE-dependent. Compared with healthy controls, sCX3CL1 levels were increased in plasma and BALF of individuals with COPD, and were associated with clinical parameters of emphysema. Our results indicate that inhibition of sCX3CL1 as well as AAT augmentation may be effective approaches to decrease excessive monocyte lung recruitment during acute and chronic inflammatory states.NEW & NOTEWORTHY Our novel findings that AAT and other inhibitors of TACE, the sheddase that controls full-length fractalkine (CX3CL1) endothelial expression, may provide fine-tuning of the CX3CL1-CX3CR1 axis specifically involved in endothelial-monocyte cross talk and leukocyte recruitment to the alveolar space, suggests that AAT and inhibitors of sCX3CL1 signaling may be harnessed to reduce lung inflammation.

Intravital Imaging of Leukocyte-Endothelial Interaction in Hindlimb Ischemia/Reperfusion Injury by Intravital Multiphoton Microscopy.

Ischemia/reperfusion injury in skeletal muscle leads to sterile inflammation and affects structure and function permanently. However, the main understanding of the molecular and cellular mechanisms mainly relies on in vitro and ex vivo investigations. Recent advances in intravital microscopy allow for insights into dynamic processes at the cellular and subcellular level under both physiological and pathophysiological conditions. Real-time intravital imaging by two-photon microscopy (2P-IVM) has emerged as a powerful tool in the evaluation of the cell-cell interaction and molecular biology of leukocytes in live animals. Acute ischemic injury in limbs may occur due to crush syndrome, compartment syndrome, and vascular diseases and injury as in acute peripheral arterial occlusion, caused by a diverse array of pathological conditions. Iatrogenic revascularization and restoration of perfusion results paradoxically in aggravated tissue injury. Furthermore, the effects of IR-injured skeletal muscle in clinical conditions such as compartment syndrome or crush syndrome may induce rhabdomyolysis and are associated with so-called remote injuries as acute kidney dysfunction. Here, we discuss the considerations for and describe a 2P-IVM method designed for visualization of leukocyte-endothelial interaction. This chapter will provide a detailed experimental setup and a step-by-step protocol for the dynamic imaging of leukocyte-endothelial-interaction in an ischemia/reperfusion injury model.

Metformin and its redox-related mechanisms of action in type 2 diabetes

Type 2 diabetes (T2D) is a long-term metabolic disease characterized by progressive β-cell functional decline and insulin resistance, which increases the risk of cardiovascular complications as well as associated-morbidity and mortality. Evidence suggests a strong relationship between hyperglycaemia, oxidative stress and the development and progression of T2D. Indeed, a hyperglycaemic state can reduce the activity of antioxidant enzymes and increase lipid peroxidation and protein oxidation products, as well as DNA damage. At present, metformin is the recommended first-line glucose-lowering agent in patients with T2D. Despite the vast clinical experience gained over several decades of use, several mechanisms of action of metformin have yet to be fully elucidated. This review provides an overview of the existing literature concerning the complicated interplay between oxidative stress and T2D and the molecular mechanisms underlying the redox-related mechanisms of action of metformin, which include (but are not limited to) interaction with AMP-activated protein kinase (AMPK)-dependent and AMPK-independent mechanisms, inhibition of gluconeogenesis and action on leukocyte–endothelium interactions.

Effects of GLP-1 receptor agonists on mitochondrial function, inflammatory markers and leukocyte-endothelium interactions in type 2 diabetes

ObjectiveType 2 diabetes (T2D) is linked to metabolic, mitochondrial and inflammatory alterations, atherosclerosis development and cardiovascular diseases (CVDs). The aim was to investigate the potential therapeutic benefits of GLP-1 receptor agonists (GLP-1 RA) on oxidative stress, mitochondrial respiration, leukocyte-endothelial interactions, inflammation and carotid intima–media thickness (CIMT) in T2D patients. Research design and methodsType 2 diabetic patients (255) and control subjects (175) were recruited, paired by age and sex, and separated into two groups: without GLP-1 RA treatment (196) and treated with GLP-1 RA (59). Peripheral blood polymorphonuclear leukocytes (PMNs) were isolated to measure reactive oxygen species (ROS) production by flow cytometry and oxygen consumption with a Clark electrode. PMNs were also used to assess leukocyte-endothelial interactions. Circulating levels of adhesion molecules and inflammatory markers were quantified by Luminex's technology, and CIMT was measured as surrogate marker of atherosclerosis. ResultsTreatment with GLP-1 RA reduced ROS production and recovered mitochondrial membrane potential, oxygen consumption and MPO levels. The velocity of leukocytes rolling over endothelial cells increased in PMNs from GLP-1 RA-treated patients, whereas rolling and adhesion were diminished. ICAM-1, VCAM-1, IL-6, TNFα and IL-12 protein levels also decreased in the GLP-1 RA-treated group, while IL-10 increased. CIMT was lower in GLP-1 RA-treated T2D patients than in T2D patients without GLP-1 RA treatment. ConclusionsGLP-1 RA treatment improves the redox state and mitochondrial respiration, and reduces leukocyte-endothelial interactions, inflammation and CIMT in T2D patients, thereby potentially diminishing the risk of atherosclerosis and CVDs.

Beneficial effects of empagliflozin and liraglutide on the cerebral microcirculation of diabetic rats.

This study aimed to evaluate the effects of the antidiabetics liraglutide, a GLP-1 analog, and empagliflozin, an SGLT-2 inhibitor, on the brain microcirculation of diabetic rats. Type 2 diabetes mellitus (DM) was experimentally induced in male Wistar rats by combining a high-fat diet and a low dose of streptozotocin (35 mg/kg). Liraglutide (100 μg/kg s.c.) and empagliflozin (10 mg/kg, oral) were administered for 5 weeks. Body weight was monitored periodically. Oral glucose tolerance, fasting glycemia, and blood triglycerides were evaluated after the treatments. Endothelial-leukocyte interactions in the brain microcirculation and structural capillary density were assessed. DM rats presented metabolic and cerebrovascular alterations. Liraglutide treatment decreased body weight and blood triglycerides of DM rats. Empagliflozin treatment improved glucose tolerance but only the combination therapy significantly reduced fasting blood glucose. Both treatments and their combination reduced leukocyte adhesion into the endothelium of brain venules. However, empagliflozin was more effective in preventing DM-induced microvascular rarefaction. These findings suggest that chronic treatment with SGLT2 inhibitors and GLP-1 receptor agonists may serve as potential therapeutic approaches to prevent microvascular complications associated with diabetes.

Improvement of hemodynamics in mesenteric microcirculation in septic shock rats by anisodamine and anisodine

Anisodamine and anisodine have been used in treatment of septic shock, but the underlying mechanism are still unclear. In the present study, the effects of anisodamine hydrobromide (Ani HBr) and anisodine hydrobromide (AT3) on the mesenteric hemodynamics in septic shock rats were performed. The rat model of septic shock was established by intravenous tail vein injection of 5 ​mg/kg lipopolysaccharide (LPS), and then treated with Ani HBr, AT3, racemic anisodine (Race Ani) or atropine (ATP). The mesenteric microcirculation was observed using the intravital microscopy. Then, the flow pattern of the microcirculation, leukocytes dynamics and the plasma levels of cytokines tumor necrosis factor (TNF)-α and interleukin-6 (IL-6) were analyzed. Compared with the control rats, reduced mean arterial pressure, increased heart rate, and slow microcirculatory blood flow was found in septic shock rats. The main abnormal flow patterns were intermittent and reciprocating motions. Ani HBr, AT3, Race Ani and ATP elevated the mean arterial pressure and reduced heart rate in septic shock rats. Ani HBr and AT3 not only restored the velocity of microcirculatory blood flow and improved the microcirculatory flow patterns, but also suppressed the LPS-induced leukocyte-endothelium interaction and releases of TNF-α and IL-6. Therefore, Ani HBr and AT3 improves hemodynamics in both macro- and microcirculation, which provide a novel experimental basis for exploring the mechanobiological mechanisms in septic shock.

Leukocyte-endothelial interaction in CKD.

Chronic kidney disease (CKD) represents an independent risk factor for cardiovascular diseases (CVD). Accordingly, CKD patients show a substantial increased risk of cardiovascular mortality. Inflammation represents an important link between CKD and CVD. The interaction between endothelial cells and effector cells of the innate immune system plays a central role in the development and progression of inflammation. Vascular injury causes endothelial dysfunction, leading to augmented oxidative stress, increased expression of leukocyte adhesion molecules and chronic inflammation. CKD induces numerous metabolic changes, creating a uremic milieu resulting in the accumulation of various uremic toxins. These toxins lead to vascular injury, endothelial dysfunction and activation of the innate immune system. Recent studies describe CKD-dependent changes in monocytes that promote endothelial dysfunction and thus CKD progression and CKD-associated CVD. The NLR family pyrin domain containing 3-interleukin-1β-interleukin-6 (NLRP3-IL-1β-IL-6) signaling pathway plays a pivotal role in the development and progression of CVD and CKD alike. Several clinical trials are investigating targeted inhibition of this pathway indicating that anti-inflammatory therapeutic strategies may emerge as novel approaches in patients at high cardiovascular risk and nonresolving inflammation. CKD patients in particular would benefit from targeted anti-inflammatory therapy, since conventional therapeutic regimens have limited efficacy in this population.

Abstract 5864: An angiogenic target of immune exclusion with checkpoint blockade in melanoma

Abstract With the development of immune checkpoint blockade to treat a variety of malignancies, better predictive biomarkers as well as new targets to further improve anti-tumor immunity remains a need. Our understanding of the role of angiogenesis in immune regulation continues to improve, and combinations of anti-angiogenesis and immune checkpoint blockade demonstrate improved clinical efficacy, as well as mechanisms for improved immune cell trafficking. Tumor biopsies from a phase I study with 46 advanced melanoma patients treated with Ipilimumab and Bevacizumab combination (Ipi-Bev) therapy, revealed activated endothelium accompanied by lymphocyte infiltration. To discover possible targets involved in the observed clinical benefit, a serological screen was performed using human protein arrays with post-treatment plasma samples of long-term patients with clinical benefit to Ipi-Bev therapy (Wu et. al., 2017; Hodi et. al., 2014). EDIL3 (EGF Like Repeats and Discoidin Domains 3), a pro-angiogenic extracellular matrix protein, was identified. Humoral responses against EDIL3 were associated with favorable clinical outcomes including improved response rates (p=0.003) and overall survival (p=0.03) to Ipi-Bev therapy. The anti-EDIL3 response was also observed to be significantly (p=0.03) related to Ipi-Bev treatment when compared with patients treated with Ipilimumab alone, anti-PD1 therapy alone, or the combination of Ipilimumab and Nivolumab in a combined analysis. Transcriptome analyses of TCGA SKCM (n=469) and BMS Checkmate 064 trial (n=90) related upregulated EDIL3 expression with enrichment of EMT, TGFβ signaling in fibroblasts, and angiogenesis signatures. Interestingly, TIDE analysis demonstrated a role for EDIL3 in T cell exclusion and immunosuppressive cancer-associated fibroblasts (CAFs) as its source in the tumor microenvironment. EDIL3 was also predicted as a biomarker of non-response to immune checkpoint blockade treatment. In vitro studies confirmed the upregulation of EDIL3 expression and secretion by patient-derived CAFs along with its role in modulating TGFβ1 mediated EMT. Mechanistically, EDIL3 was found to interfere with leukocyte-endothelial interactions by disturbing LFA-1/ICAM1 mediated adhesion and inhibited T cell transmigration in 2-D and microfluidic 3-D coculture studies with patient-derived tumor endothelial cells. Our findings suggest that the humoral response against EDIL3 may serve as one of the underlying mechanisms involved in effectuating an excluded to an inflamed phenotype observed in responders of checkpoint blockade treatment. This study develops EDIL3 as a potential target to enhance cytotoxic immune responses and improve the outcomes of combination immune therapy. Studies are ongoing for targeted inhibition of EDIL3 with implications for therapeutic application to promote anti-tumor immunity. Citation Format: Saba Tabasum, Dinesh Thapa, Anita Giobbie-Hurder, Jason L. Weirather, Xinqi Wu, Marco Campisi, Xiaoyun Li, Jingjing Li, Michael P. Manos, David A. Barbie, F. Stephen Hodi. An angiogenic target of immune exclusion with checkpoint blockade in melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5864.

Serine proteases mediate leukocyte recruitment and hepatic microvascular injury in the acute phase following extended hepatectomy.

Post-hepatectomy liver failure (PHLF) is the main limitation of extended liver resection. The molecular mechanism and the role of leukocytes in the development of PHLF remain to be unveiled. We aimed to address the impact of serine proteases (SPs) on the acute phase after liver resection by intravitally analyzing leukocyte recruitment and changes in hemodynamics and microcirculation of the liver. C57BL/6 mice undergoing 60% partial hepatectomy were treated with aprotinin (broad-spectrum SP inhibitor), tranexamic acid (plasmin inhibitor), or vehicle. Sham-operated animals served as controls. In vivo fluorescence microscopy was used to quantify leukocyte-endothelial interactions immediately after, as well as 120 min after partial hepatectomy in postsinusoidal venules, along with measurement of sinusoidal perfusion rate and postsinusoidal shear rate. Recruitment of leukocytes, neutrophils, T cells, and parameters of liver injury were assessed in tissue/blood samples. Leukocyte recruitment, sinusoidal perfusion failure rate, and shear rate were significantly increased in mice after 60% partial hepatectomy compared to sham-operated animals. The inhibition of SPs or plasmin significantly attenuated leukocyte recruitment and improved the perfusion rate in the remnant liver. ICAM-1 expression and neutrophil recruitment significantly increased after 60% partial hepatectomy and were strongly reduced by plasmin inhibition. Endothelial activation and leukocyte recruitment in the liver in response to the increment of sinusoidal shear rate were hallmarks in the acute phase after liver resection. SPs mediated leukocyte recruitment and contributed to the impairment of sinusoidal perfusion in an ICAM-1-dependent manner in the acute phase after liver resection.