Getting leukocytes to the site of inflammation

Antioxidant Therapy in Pancreatitis

Pancreatitis is pathologic inflammation of the pancreas characterized by acinar cell destruction and oxidative stress. Repeated pancreatic insults can result in the development of chronic pancreatitis, characterized by irreversible fibrosis of the pancreas and many secondary sequelae, ultimately leading to the loss of this important organ. We review acute pancreatitis, chronic pancreatitis, and pancreatitis-related complications. We take a close look at the pathophysiology with a focus on oxidative stress and how it contributes to the complications of the disease. We also take a deep dive into the evolution and current status of advanced therapies for management including dietary modification, antioxidant supplementation, and nuclear factor erythroid-2-related factor 2-Kelch-like ECH-associated protein 1(Nrf2-keap1) pathway activation. In addition, we discuss the surgeries aimed at managing pain and preventing further endocrine dysfunction, such as total pancreatectomy with islet auto-transplantation.

Phaseolin Attenuates Lipopolysaccharide-Induced Inflammation in RAW 264.7 Cells and Zebrafish

Kushen (Radix Sophorae flavescentis) is used to treat ulcerative colitis, tumors, and pruritus. Recently, phaseolin, formononetin, matrine, luteolin, and quercetin, through a network pharmacology approach, were tentatively identified as five bioactive constituents responsible for the anti-inflammatory effects of S. flavescentis. However, the role of phaseolin (one of the primary components of S. flavescentis) in the direct regulation of inflammation and inflammatory processes is not well known. In this study, the beneficial role of phaseolin against inflammation was explored in lipopolysaccharide (LPS)-induced inflammation models of RAW 264.7 macrophages and zebrafish larvae. Phaseolin inhibited LPS-mediated production of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS), without affecting cell viability. In addition, phaseolin suppressed pro-inflammatory mediators such as cyclooxygenase 2 (COX-2), interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and interleukin-6 (IL-6) in a dose-dependent manner. Furthermore, phaseolin reduced matrix metalloproteinase (MMP) activity as well as macrophage adhesion in vitro and the recruitment of leukocytes in vivo by downregulating Ninjurin 1 (Ninj1), an adhesion molecule. Finally, phaseolin inhibited the nuclear translocation of nuclear factor-kappa B (NF-κB). In view of the above, our results suggest that phaseolin could be a potential therapeutic candidate for the management of inflammation.

The Tumour Vasculature as a Target to Modulate Leucocyte Trafficking

Simple Summary

Tumour blood vessels, characterised by abnormal morphology and function, create an immunosuppressive tumour microenvironment via restricting the appropriate leucocyte subsets trafficking. Strategies to trigger phenotypic alteration in tumour vascular system to resemble normal vascular system, named vascular normalisation, promote effective trafficking of leucocytes into tumours through enhancing the interactions between leucocytes and endothelial cells. This review specifically demonstrates how targeting tumour blood vessels modulates the critical steps of leucocyte trafficking. Furthermore, selective regulation of leucocyte subsets trafficking in tumours can be achieved by vasculature-targeting strategies, contributing to improved immunotherapy and thereby delayed tumour progression.

Abstract

The effectiveness of immunotherapy against solid tumours is dependent on the appropriate leucocyte subsets trafficking and accumulating in the tumour microenvironment (TME) with recruitment occurring at the endothelium. Such recruitment involves interactions between the leucocytes and the endothelial cells (ECs) of the vessel and occurs through a series of steps including leucocyte capture, their rolling, adhesion, and intraluminal crawling, and finally leucocyte transendothelial migration across the endothelium. The tumour vasculature can curb the trafficking of leucocytes through influencing each step of the leucocyte recruitment process, ultimately producing an immunoresistant microenvironment. Modulation of the tumour vasculature by strategies such as vascular normalisation have proven to be efficient in facilitating leucocyte trafficking into tumours and enhancing immunotherapy. In this review, we discuss the underlying mechanisms of abnormal tumour vasculature and its impact on leucocyte trafficking, and potential strategies for overcoming the tumour vascular abnormalities to boost immunotherapy via increasing leucocyte recruitment.

Stem cell-based vascularization of microphysiological systems

Microphysiological systems (MPSs) (i.e., tissue or organ chips) exploit microfluidics and 3D cell culture to mimic tissue and organ-level physiology. The advent of human induced pluripotent stem cell (hiPSC) technology has accelerated the use of MPSs to study human disease in a range of organ systems. However, in the reduction of system complexity, the intricacies of vasculature are an often-overlooked aspect of MPS design. The growing library of pluripotent stem cell-derived endothelial cell and perivascular cell protocols have great potential to improve the physiological relevance of vasculature within MPS, specifically for in vitro disease modeling. Three strategic categories of vascular MPS are outlined: self-assembled, interface focused, and 3D biofabricated. This review discusses key features and development of the native vasculature, linking that to how hiPSC-derived vascular cells have been generated, the state of the art in vascular MPSs, and opportunities arising from interdisciplinary thinking.

Macrophages in microgravity: the impact of space on immune cells

The effects of a microgravity environment on the myriad types of immune cells present within the human body have been assessed both by bench-scale simulation and suborbital methods, as well as in true spaceflight. Macrophages have garnered increased research interest in this context in recent years. Their functionality in both immune response and tissue remodeling makes them a unique cell to investigate in regards to gravisensitive effects as well as parameters of interest that could impact astronaut health. Here, we review and summarize the literature investigating the effects of microgravity on macrophages and monocytes regarding the microgravity environment simulation/generation methods, cell sources, experiment durations, and parameters of interest utilized within the field. We discuss reported findings on the impacts of microgravity on macrophage/monocyte structure, adhesion and migration, proliferation, genetic expression, cytokine secretion, and reactive oxygen species production, as well as polarization. Based on this body of data, we make recommendations to the field for careful consideration of experimental design to complement existing reports, as the multitude of disparate study methods previously published can make drawing direct comparisons difficult. However, the breadth of different testing methodologies can also lend itself to attempting to identify the most robust and consistent responses to microgravity across various testing conditions.

Label-Free Biophysical Markers from Whole Blood Microfluidic Immune Profiling Reveal Severe Immune Response Signatures

Disease manifestation and severity from acute infections are often due to hyper-aggressive host immune responses which change within minutes. Current methods for early diagnosis of infections focus on detecting low abundance pathogens, which are time-consuming, of low sensitivity, and do not reflect the severity of the pathophysiology appropriately. The approach here focuses on profiling the rapidly changing host inflammatory response, which in its over-exuberant state, leads to sepsis and death. A 15-min label-free immune profiling assay from 20 µL of unprocessed blood using unconventional L and Inverse-L shaped pillars of deterministic lateral displacement microfluidic technology is developed. The hydrodynamic interactions of deformable immune cells enable simultaneous sorting and immune response profiling in whole blood. Preliminary clinical study of 85 donors in emergency department with a spectrum of immune response states from healthy to severe inflammatory response shows correlation with biophysical markers of immune cell size, deformability, distribution, and cell counts. The speed of patient stratification demonstrated here has promising impact in deployable point-of-care systems for acute infections triage, risk management, and resource allocation at emergency departments, where clinical manifestation of infection severity may not be clinically evident as compared to inpatients in the wards or intensive care units.

Induction of scaffold angiogenesis by recipient vasculature precision micropuncture

The success of engineered tissues continues to be limited by time to vascularization and perfusion. Here, we studied the effects of precision injury to a recipient macrovasculature in promoting neovessel formation in an adjacently placed scaffold. Segmental 60 μm diameter micropunctures (MP) were created in the recipient rat femoral artery and vein followed by coverage with a simple collagen scaffold. Scaffolds were harvested at 24, 48, 72, and 96 h post-implantation for detailed analysis. Those placed on top of an MP segment showed an earlier and more robust cellular infiltration, including both endothelial cells (CD31) and macrophages (F4/80), compared to internal non-micropunctured control limbs (p < 0.05). At the 96-hour timepoint, MP scaffolds demonstrated an increase in physiologic perfusion (p < 0.003) and a 2.5-fold increase in capillary network formation (p < 0.001). These were attributed to an overall upsurge in small vessel quantity. Furthermore, MP positioned scaffolds demonstrated significant increases in many modulators of angiogenesis, including VEGFR2 and Tie-2 despite a decrease in HIF-1α at all timepoints. This study highlights a novel microsurgical approach that can be used to rapidly vascularize or inosculate contiguously placed scaffolds and grafts. Thereby, offering an easily translatable route towards the creation of thicker and more clinically relevant engineered tissues.

The Role of Creatine in the Development and Activation of Immune Responses

The use of dietary supplements has become increasingly common over the past 20 years. Whereas supplements were formerly used mainly by elite athletes, age and fitness status no longer dictates who uses these substances. Indeed, many nutritional supplements are recommended by health care professionals to their patients. Creatine (CR) is a widely used dietary supplement that has been well-studied for its effects on performance and health. CR also aids in recovery from strenuous bouts of exercise by reducing inflammation. Although CR is considered to be very safe in recommended doses, a caveat is that a preponderance of the studies have focused upon young athletic individuals; thus there is limited knowledge regarding the effects of CR on children or the elderly. In this review, we examine the potential of CR to impact the host outside of the musculoskeletal system, specifically, the immune system, and discuss the available data demonstrating that CR can impact both innate and adaptive immune responses, together with how the effects on the immune system might be exploited to enhance human health.

Lack of CD34 delays bacterial endotoxin-induced lung inflammation

Background

CD34, a pan-selectin binding protein when glycosylated, has been shown to be involved in leukocyte migration to the site of inflammation. However, only one report is available on the expression and role of CD34 in neutrophil recruitment during acute lung inflammation.

Methods

We proceeded to study the role of CD34 in lung neutrophil migration using mouse model of endotoxin induced acute lung inflammation and studied over multiple time points, in generic CD34 knock-out (KO) strain.

Results

While there was no difference in BAL total or differential leukocyte counts, lung MPO content was lower in LPS exposed KO compared to WT group at 3 h time-point (p = 0.0308). The MPO levels in CD34 KO mice begin to rise at 9 h (p = 0.0021), as opposed to an early 3 h rise in WT mice (p = 0.0001), indicating that KO mice display delays in lung neutrophil recruitment kinetics. KO mice do not loose endotoxin induced lung vascular barrier properties as suggested by lower BAL total protein at 3 h (p = 0.0452) and 24 h (p = 0.0113) time-points. Several pro-inflammatory cytokines and chemokines (TNF-α, IL-1β, KC, MIP-1α, IL-6, IL-10 and IL-12 p70 sub-unit; p < 0.05) had higher levels in WT compared to KO group, at 3 h. Lung immunofluorescence in healthy WT mice reveals CD34 expression in the bronchiolar epithelium, in addition to alveolar septa.

Conclusion

Thus, given CD34′s pan-selectin affinity, and expression in the bronchiolar epithelium as well as alveolar septa, our study points towards a role of CD34 in lung neutrophil recruitment but not alveolar migration, cytokine expression and lung inflammation.

Dysregulation of Leukocyte Trafficking in Type 2 Diabetes: Mechanisms and Potential Therapeutic Avenues

Type 2 Diabetes Mellitus (T2DM) is a chronic inflammatory disorder that is characterized by chronic hyperglycemia and impaired insulin signaling which in addition to be caused by common metabolic dysregulations, have also been associated to changes in various immune cell number, function and activation phenotype. Obesity plays a central role in the development of T2DM. The inflammation originating from obese adipose tissue develops systemically and contributes to insulin resistance, beta cell dysfunction and hyperglycemia. Hyperglycemia can also contribute to chronic, low-grade inflammation resulting in compromised immune function. In this review, we explore how the trafficking of innate and adaptive immune cells under inflammatory condition is dysregulated in T2DM. We particularly highlight the obesity-related accumulation of leukocytes in the adipose tissue leading to insulin resistance and beta-cell dysfunction and resulting in hyperglycemia and consequent changes of adhesion and migratory behavior of leukocytes in different vascular beds. Thus, here we discuss how potential therapeutic targeting of leukocyte trafficking could be an efficient way to control inflammation as well as diabetes and its vascular complications.

Analysis of Differentially Expressed Genes in Endothelial Cells Following Tumor Cell Adhesion, and the Role of PRKAA2 and miR-124-3p

Tumor cell adhesion to the endothelium is one pattern of tumor-endothelium interaction and a key step during tumor metastasis. Endothelium integrity is an important barrier to prevent tumor invasion and metastasis. Changes in endothelial cells (ECs) due to tumor cell adhesion provide important signaling mechanisms for the angiogenesis and metastasis of tumor cells. However, the changes happened in endothelial cells when tumor-endothelium interactions are still unclear. In this study, we used Affymetrix Gene Chip Human Transcriptome Array 2.0. and quantitative real-time PCR (qPCR) to clarify the detailed gene alteration in endothelial cells adhered by prostate tumor cells PC-3M. A total of 504 differentially expressed mRNAs and 444 lncRNAs were obtained through chip data analysis. Gene Ontology (GO) function analysis showed that differentially expressed genes (DEGs) mainly mediated gland development and DNA replication at the biological level; at the cell component level, they were mainly involved in the mitochondrial inner membrane; and at the molecular function level, DEGs were mainly enriched in ATPase activity and catalytic activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) signal pathway analysis showed that the DEGs mainly regulated pathways in cancer, cell cycle, pyrimidine metabolism, and the mTOR signaling pathway. Then, we constructed a protein-protein interaction functional network and mRNA-lncRNA interaction network using Cytoscape v3.7.2. to identify core genes, mRNAs, and lncRNAs. The miRNAs targeted by the core mRNA PRKAA2 were predicted using databases (miRDB, RNA22, and Targetscan). The qPCR results showed that miR-124-3p, the predicted target miRNA of PRKAA2, was significantly downregulated in endothelial cells adhered by PC-3M. With a dual luciferase reporter assay, the binding of miR-124-3p with PRKAA2 3'UTR was confirmed. Additionally, by using the knockdown lentiviral vectors of miR-124-3p to downregulate the miR-124-3p expression level in endothelial cells, we found that the expression level of PRKAA2 increased accordingly. Taken together, the adhesion of tumor cells had a significant effect on mRNAs and lncRNAs in the endothelial cells, in which PRKAA2 is a notable changed molecule and miR-124-3p could regulate its expression and function in endothelial cells.

Endothelial Regulation by Exogenous Annexin A1 in Inflammatory Response and BBB Integrity Following Traumatic Brain Injury

Background and Target

Following brain trauma, blood–brain barrier (BBB) disruption and inflammatory response are critical pathological steps contributing to secondary injury, leading to high mortality and morbidity. Both pathologies are closely associated with endothelial remodeling. In the present study, we concentrated on annexin A1 (ANXA1) as a novel regulator of endothelial function after traumatic brain injury.

Methods

After establishing controlled cortical impact (CCI) model in male mice, human recombinant ANXA1 (rANXA1) was administered intravenously, followed by assessments of BBB integrity, brain edema, inflammatory response, and neurological deficits.

Result

Animals treated with rANXA1 (1 μg/kg) at 1 h after CCI exhibited optimal BBB protection including alleviated BBB disruption and brain edema, as well as endothelial junction proteins loss. The infiltrated neutrophils and inflammatory cytokines were suppressed by rANXA1, consistent with decreased adhesive and transmigrating molecules from isolated microvessels. Moreover, rANXA1 attenuated the neurological deficits induced by CCI. We further found that the Ras homolog gene family member A (RhoA) inhibition has similar effect as rANXA1 in ameliorating brain injuries after CCI, whereas rANXA1 suppressed CCI-induced RhoA activation.

Conclusion

Our findings suggest that the endothelial remodeling by exogenous rANXA1 corrects BBB disruption and inflammatory response through RhoA inhibition, hence improving functional outcomes in CCI mice.

Engineering of Neutrophil Membrane Camouflaging Nanoparticles Realizes Targeted Drug Delivery for Amplified Antitumor Therapy

Purpose

Although the neutrophil membrane (NM)-based nanoparticulate delivery system has exhibited rapid advances in tumor targeting stemmed from the inherited instinct, the antitumor effect requires further improvement due to inefficient cellular internalization in the absence of specific interactions between NM-coated nanoparticles and tumor cells.

Methods

Herein, we fabricated drug-paclitaxel loaded NM camouflaging nanoparticles (TNM-PN) modified with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), favorable for the cellular internalization.

Results

The results showed that TNM-PN exerted a significant cytotoxicity to tumor cells by TRAIL-mediated endocytosis and strong adhesion to inflamed endothelial cells in vitro. Due to TRAIL modification as well as the adhesive interactions between neutrophil and inflamed tumor vascular endothelial cells, tumors in TNM-PN group exhibited almost 2-fold higher fluorescence intensities than that of NM camouflaging nanoparticles and 3-fold higher than that of bare nanoparticles, respectively. Significant tumor inhibition and survival rates of mice were achieved in TNM-PN group as a consequence of prolonged blood circulations to 48 h and preferential tumor accumulations, which was ascribed to targeting adhesion originated from NM to immune evasion and subsequent excellent cellular internalization.

Conclusion

The research unveiled a novel strategy of amplifying cellular internalization based on NM coating nanotechnology to boost antitumor efficacy.

Complement Receptors and Their Role in Leukocyte Recruitment and Phagocytosis

The complement system is deeply embedded in our physiology and immunity. Complement activation generates a multitude of molecules that converge simultaneously on the opsonization of a target for phagocytosis and activation of the immune system via soluble anaphylatoxins. This response is used to control microorganisms and to remove dead cells, but also plays a major role in stimulating the adaptive immune response and the regeneration of injured tissues. Many of these effects inherently depend on complement receptors expressed on leukocytes and parenchymal cells, which, by recognizing complement-derived molecules, promote leukocyte recruitment, phagocytosis of microorganisms and clearance of immune complexes. Here, the plethora of information on the role of complement receptors will be reviewed, including an analysis of how this functionally and structurally diverse group of molecules acts jointly to exert the full extent of complement regulation of homeostasis.

ECM-regulation of autophagy: The yin and the yang of autophagy during wound healing

Wound healing is a complex sequence of tissue protection, replacement, and reorganization leading to regenerated tissue. Disruption of any of these steps results in the process being incomplete as an ulcer or over-exuberant as a hypertrophic scar. Over the past decade, it has become evident that the extracellular matrix and associated components orchestrate this process. However, the cellular events that are induced by the extracellular matrix to accomplish wound healing remain to be defined. Herein we propose that matrix-regulated cellular macro-autophagy is key to both the tissue replacement and resolution stages of healing by directing cellular function or apoptosis. Further, disruptions in matrix turnover alter autophagic function leading to chronic wounds or scarring. While the literature that directly investigates autophagy during wound healing is sparse, the emerging picture supports our proposing a model of the centrality of the matrix-autophagy modulation as central to physiologic and pathologic healing.

Computational and network pharmacology analysis of bioflavonoids as possible natural antiviral compounds in COVID-19

Bioflavonoids are the largest group of plant-derived polyphenolic compounds with diverse biological potential and have also been proven efficacious in the treatment of Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS). The present investigation validates molecular docking, simulation, and MM-PBSA studies of fifteen bioactive bioflavonoids derived from plants as a plausible potential antiviral in the treatment of COVID-19. Molecular docking studies for 15 flavonoids on the three SARS CoV-2 proteins, non-structural protein-15 Endoribonuclease (NSP15), the receptor-binding domain of spike protein (RBD of S protein), and main protease (Mpro/3CLpro) were performed and selected protein-ligand complexes were subjected to Molecular Dynamics simulations. The molecular dynamics trajectories were subjected to free energy calculation by the MM-PBSA method. All flavonoids were further assessed for their effectiveness as adjuvant therapy by network pharmacology analysis on the target proteins. The network pharmacology analysis suggests the involvement of selected bioflavonoids in the modulation of multiple signaling pathways like p53, FoxO, MAPK, Wnt, Rap1, TNF, adipocytokine, and leukocyte transendothelial migration which plays a significant role in immunomodulation, minimizing the oxidative stress and inflammation. Molecular docking and molecular dynamics simulation studies illustrated the potential of glycyrrhizic acid, amentoflavone, and mulberroside in inhibiting key SARS-CoV-2 proteins and these results could be exploited further in designing future ligands from natural sources.

Extracellular RNA as a Versatile DAMP and Alarm Signal That Influences Leukocyte Recruitment in Inflammation and Infection

Upon vascular injury, tissue damage, ischemia, or microbial infection, intracellular material such as nucleic acids and histones is liberated and comes into contact with the vessel wall and circulating blood cells. Such "Danger-associated molecular patterns" (DAMPs) may thus have an enduring influence on the inflammatory defense process that involves leukocyte recruitment and wound healing reactions. While different species of extracellular RNA (exRNA), including microRNAs and long non-coding RNAs, have been implicated to influence inflammatory processes at different levels, recent in vitro and in vivo work has demonstrated a major impact of ribosomal exRNA as a prominent DAMP on various steps of leukocyte recruitment within the innate immune response. This includes the induction of vascular hyper-permeability and vasogenic edema by exRNA via the activation of the "vascular endothelial growth factor" (VEGF) receptor-2 system, as well as the recruitment of leukocytes to the inflamed endothelium, the M1-type polarization of inflammatory macrophages, or the role of exRNA as a pro-thrombotic cofactor to promote thrombosis. Beyond sterile inflammation, exRNA also augments the docking of bacteria to host cells and the subsequent microbial invasion. Moreover, upon vessel occlusion and ischemia, the shear stress-induced release of exRNA initiates arteriogenesis (i.e., formation of natural vessel bypasses) in a multistep process that resembles leukocyte recruitment. Although exRNA can be counteracted for by natural circulating RNase1, under the conditions mentioned, only the administration of exogenous, thermostable, non-toxic RNase1 provides an effective and safe therapeutic regimen for treating the damaging activities of exRNA. It remains to be investigated whether exRNA may also influence viral infections (including COVID-19), e.g., by supporting the interaction of host cells with viral particles and their subsequent invasion. In fact, as a consequence of the viral infection cycle, massive amounts of exRNA are liberated, which can provoke further tissue damage and enhance virus dissemination. Whether the application of RNase1 in this scenario may help to limit the extent of viral infections like COVID-19 and impact on leukocyte recruitment and emigration steps in immune defense in order to limit the extent of associated cardiovascular diseases remains to be studied.

Recent efforts in drug discovery on vascular inflammation and consequent atherosclerosis

Introduction: Preservation of vascular endothelium integrity and maintenance of its full functionality are fundamental aspects in order to avoid both cardiovascular and non-cardiovascular diseases.Areas covered: Although a massive endothelial disruption is a rare condition, caused by acute and uncontrolled inflammatory responses (e.g. the cytokine storm induced by SARS-CoV-2 infection), more frequently the vascular tree is the first target of slowly progressive inflammatory processes which affect the integrity of endothelium and its 'barrier' function, supporting the onset of atherosclerotic plaque and spreading inflammation. This endothelial dysfunction leads to decrease NO biosynthesis, impaired regulation of vascular tone, and increased platelet aggregation. Such chronic subclinic inflammation leads to macrophage infiltration in atherosclerotic lesions. Therefore, many efforts should be addressed to find useful approaches to preserve vascular endothelium from inflammation. In this review, the authors have evaluated the most recent strategies to counteract this pathological condition.Expert opinion: The therapeutic and nutraceutical approaches represent useful tools to treat or prevent different phases of vascular inflammation. In particular, the pharmacological approach should be used in advanced phases characterized by clinical signs of vascular disease, whilst the nutraceutical approach may represent a promising preventive strategy to preserve the integrity of the endothelial tissue.

CD38: An Immunomodulatory Molecule in Inflammation and Autoimmunity

CD38 is a molecule that can act as an enzyme, with NAD-depleting and intracellular signaling activity, or as a receptor with adhesive functions. CD38 can be found expressed either on the cell surface, where it may face the extracellular milieu or the cytosol, or in intracellular compartments, such as endoplasmic reticulum, nuclear membrane, and mitochondria. The main expression of CD38 is observed in hematopoietic cells, with some cell-type specific differences between mouse and human. The role of CD38 in immune cells ranges from modulating cell differentiation to effector functions during inflammation, where CD38 may regulate cell recruitment, cytokine release, and NAD availability. In line with a role in inflammation, CD38 appears to also play a critical role in inflammatory processes during autoimmunity, although whether CD38 has pathogenic or regulatory effects varies depending on the disease, immune cell, or animal model analyzed. Given the complexity of the physiology of CD38 it has been difficult to completely understand the biology of this molecule during autoimmune inflammation. In this review, we analyze current knowledge and controversies regarding the role of CD38 during inflammation and autoimmunity and novel molecular tools that may clarify current gaps in the field.

Cellular dynamics of myogenic cell migration: molecular mechanisms and implications for skeletal muscle cell therapies

Directional cell migration is a critical process underlying morphogenesis and post-natal tissue regeneration. During embryonic myogenesis, migration of skeletal myogenic progenitors is essential to generate the anlagen of limbs, diaphragm and tongue, whereas in post-natal skeletal muscles, migration of muscle satellite (stem) cells towards regions of injury is necessary for repair and regeneration of muscle fibres. Additionally, safe and efficient migration of transplanted cells is critical in cell therapies, both allogeneic and autologous. Although various myogenic cell types have been administered intramuscularly or intravascularly, functional restoration has not been achieved yet in patients with degenerative diseases affecting multiple large muscles. One of the key reasons for this negative outcome is the limited migration of donor cells, which hinders the overall cell engraftment potential. Here, we review mechanisms of myogenic stem/progenitor cell migration during skeletal muscle development and post-natal regeneration. Furthermore, strategies utilised to improve migratory capacity of myogenic cells are examined in order to identify potential treatments that may be applied to future transplantation protocols.

Manipulation of immune‒vascular crosstalk: new strategies towards cancer treatment

Tumor vasculature is characterized by aberrant structure and function, resulting in immune suppressive profiles of tumor microenvironment through limiting immune cell infiltration into tumors, endogenous immune surveillance and immune cell function. Vascular normalization as a novel therapeutic strategy tends to prune some of the immature blood vessels and fortify the structure and function of the remaining vessels, thus improving immune stimulation and the efficacy of immunotherapy. Interestingly, the presence of "immune‒vascular crosstalk" enables the formation of a positive feedback loop between vascular normalization and immune reprogramming, providing the possibility to develop new cancer therapeutic strategies. The applications of nanomedicine in vascular-targeting therapy in cancer have gained increasing attention due to its specific physical and chemical properties. Here, we reviewed the recent advances of effective routes, especially nanomedicine, for normalizing tumor vasculature. We also summarized the development of enhancing nanoparticle-based anticancer drug delivery via the employment of transcytosis and mimicking immune cell extravasation. This review explores the potential to optimize nanomedicine-based therapeutic strategies as an alternative option for cancer treatment.

A Multifunctional Role of Leucine-Rich α-2-Glycoprotein 1 in Cutaneous Wound Healing Under Normal and Diabetic Conditions

Delayed wound healing is commonly associated with diabetes. It may lead to amputation and death if not treated in a timely fashion. Limited treatments are available partially due to the poor understanding of the complex disease pathophysiology. Here, we investigated the role of leucine-rich α-2-glycoprotein 1 (LRG1) in normal and diabetic wound healing. First, our data showed that LRG1 was significantly increased at the inflammation stage of murine wound healing, and bone marrow-derived cells served as a major source of LRG1. LRG1 deletion causes impaired immune cell infiltration, reepithelialization, and angiogenesis. As a consequence, there is a significant delay in wound closure. On the other hand, LRG1 was markedly induced in diabetic wounds in both humans and mice. LRG1-deficient mice were resistant to diabetes-induced delay in wound repair. We further demonstrated that this could be explained by the mitigation of increased neutrophil extracellular traps (NETs) in diabetic wounds. Mechanistically, LRG1 mediates NETosis in an Akt-dependent manner through TGFβ type I receptor kinase ALK5. Taken together, our studies demonstrated that LRG1 derived from bone marrow cells is required for normal wound healing, revealing a physiological role for this glycoprotein, but that excess LRG1 expression in diabetes is pathogenic and contributes to chronic wound formation.

Clinical Applications of Extracellular Vesicles in the Diagnosis and Treatment of Traumatic Brain Injury

Extracellular vesicles (EVs) have emerged as key mediators of cell-cell communication during homeostasis and in pathology. Central nervous system (CNS)-derived EVs contain cell type-specific surface markers and intralumenal protein, RNA, DNA, and metabolite cargo that can be used to assess the biochemical and molecular state of neurons and glia during neurological injury and disease. The development of EV isolation strategies coupled with analysis of multi-plexed biomarker and clinical data have the potential to improve our ability to classify and treat traumatic brain injury (TBI) and resulting sequelae. Additionally, their ability to cross the blood-brain barrier (BBB) has implications for both EV-based diagnostic strategies and for potential EV-based therapeutics. In the present review, we discuss encouraging data for EV-based diagnostic, prognostic, and therapeutic strategies in the context of TBI monitoring and management.

sLeX Expression Delineates Distinct Functional Subsets of Human Blood Central and Effector Memory T Cells

Sialyl Lewis X (sLeX) regulates T cell trafficking from the vasculature into skin and sites of inflammation, thereby playing a critical role in immunity. In healthy persons, only a small proportion of human blood T cells express sLeX, and their function is not fully defined. Using a combination of biochemical and functional studies, we find that human blood sLeX+CD4+T cells comprise a subpopulation expressing high levels of Th2 and Th17 cytokines, chemokine receptors CCR4 and CCR6, and the transcription factors GATA-3 and RORγT. Additionally, sLeX+CD4+T cells exclusively contain the regulatory T cell population (CD127lowCD25high and FOXP3+) and characteristically display immune-suppressive molecules, including the coinhibitor receptors PD-1 and CTLA-4. Among CD8+T cells, sLeX expression distinguishes a subset displaying low expression of cytotoxic effector molecules, perforin and granzyme β, with reduced degranulation and CD57 expression and, consistently, marginal cytolytic capacity after TCR engagement. Furthermore, sLeX+CD8+T cells present a pattern of features consistent with Th cell-like phenotype, including release of pertinent Tc2 cytokines and elevated expression of CD40L. Together, these findings reveal that sLeX display is associated with unique functional specialization of both CD4+ and CD8+T cells and indicate that circulating T cells that are primed to migrate to lesional sites at onset of inflammation are not poised for cytotoxic function.

Equid Herpesvirus-1 Exploits the Extracellular Matrix of Mononuclear Cells to Ensure Transport to Target Cells

Mononuclear cells are the first line of defense against microbial infection. Yet, several viruses have evolved different mechanisms to overcome host defenses to ensure their spread. Here, we show unique mechanisms of how equid herpesvirus-1 manipulates peripheral blood mononuclear cells (PBMC) to travel further in the body. (1) "PBMC-hitching": at the initial contact, herpesviruses lurk in the extracellular matrix (ECM) of PBMC without entering the cells. The virus exploits the components of the ECM to bind, transport, and then egress to infect other cells. (2) "Intracellular delivery": transendothelial migration is a physiological mechanism where mononuclear cells can transmigrate through the endothelial cells. The virus was intangible and probably did not interfere with such a mechanism where the infected PBMC can probably deliver the virus inside the endothelium. (3) "Classical-fusion": this process is well mastered by herpesviruses due to a set of envelope glycoproteins that facilitate cell-cell fusion and virus spread.

The VE-Cadherin/β-catenin signalling axis regulates immune cell infiltration into tumours

Vascular normalisation, the process that reverses the structural and functional abnormalities seen in tumour-associated vessels, is also accompanied by changes in leucocyte trafficking. Our previous studies have shown the normalisation effects of the agent CD5-2 which acts to stabilise VE-Cadherin leading to increased penetration of CD8⁺ T cells but decreased infiltration of neutrophils (CD11b⁺Gr1^hi) into tumour parenchyma. In the present study, we demonstrate that VE-Cadherin stabilisation through CD5-2 treatment of purified endothelial cells (ECs) results in a similar leucocyte-selective regulation of transmigration, suggesting the existence of an endothelial specific intrinsic mechanism. Further, we show by RNA sequencing (RNA-seq)-based transcriptomic analysis, that treatment of ECs with CD5-2 regulates chemokines known to be involved in leucocyte transmigration, including upregulation of CCL2 and CXCL10 that facilitate CD8⁺ T cell transmigration. Both in vitro and in vivo mechanistic studies revealed that the increased CCL2 expression was dependent on expression of VE-Cadherin and downstream activation of the AKT/GSK3β/β-catenin/TCF4 signalling pathway. CD5-2 treatment also contributed to the reorganisation of the cytoskeleton, inducing reorganisation of stress fibres to circumferential actin, which previously has been described as associated with the stabilisation of the endothelial barrier, and amplification of the transcellular migration of CD8⁺ T cells. Thus, we propose that promotion of endothelial junctional integrity during vascular normalisation not only inhibits vascular leak but also resets the endothelial dependent regulation of immune cell infiltration.

Leukocyte populations and their cell adhesion molecules expression in newborn dromedary camel calves

Background and Aim

Different properties of the newborn immune system have been characterized in many species. For the newborn camel calf, however, the phenotype and composition of blood leukocytes have so far not been evaluated. The current study aimed to analyze the distribution of leukocyte subpopulations and their expression pattern of cell adhesion molecules in newborn and adult dromedary camels.

Materials and Methods

Blood samples were collected from 17 newborn camel calves and 32 adult camels. For each sample, total leukocytes were separated and analyzed for their composition and cell adhesion molecules expression by flow cytometry.

Results

In comparison to adult camels, newborn camel calves had higher leukocyte numbers and higher numbers of neutrophils, monocytes, and lymphocytes but lower numbers of eosinophils in their blood. Among the lymphocyte populations in calves, the fractions of B cells and γ^δ T cells were elevated when compared to adults, whereas CD4-positive T cells were reduced. The comparison between camel calves and adult camels revealed significantly lower expression of the cell adhesion molecules CD11a, CD11b, and CD18 on granulocytes, monocytes, and lymphocytes in calves.

Conclusion

Newborn camel calves show a distinct composition and phenotype pattern of blood leukocytes when compared to adult camels. The observed rise in many leukocyte populations in calf blood may be due to reduced migratory activity in calf leukocyte populations.

Tackling Resistance to Cancer Immunotherapy: What Do We Know?

Cancer treatment has evolved tremendously in the last few decades. Immunotherapy has been considered to be the forth pillar in cancer treatment in addition to conventional surgery, radiotherapy, and chemotherapy. Though immunotherapy has resulted in impressive response, it is generally limited to a small subset of patients. Understanding the mechanisms of resistance toward cancer immunotherapy may shed new light to counter that resistance. In this review, we highlighted and summarized two major hurdles (recognition and attack) of cancer elimination by the immune system. The mechanisms of failure of some available immunotherapy strategies were also described. Moreover, the significance role of immune compartment for various established cancer treatments were also elucidated in this review. Then, the mechanisms of combinatorial treatment of various conventional cancer treatment with immunotherapy were discussed. Finally, a strategy to improve immune cancer killing by characterizing cancer immune landscape, then devising treatment based on that cancer immune landscape was put forward.

Tolerogenic vaccines: Targeting the antigenic and cytokine niches of FOXP3+ regulatory T cells

FOXP3+ regulatory T cells (Tregs) constitute a critical barrier that enforces tolerance to both the self-peptidome and the extended-self peptidome to ensure tissue-specific resistance to autoimmune, allergic, and other inflammatory disorders. Here, we review intuitive models regarding how T cell antigen receptor (TCR) specificity and antigen recognition efficiency shape the Treg and conventional T cell (Tcon) repertoires to adaptively regulate T cell maintenance, tissue-residency, phenotypic stability, and immune function in peripheral tissues. Three zones of TCR recognition efficiency are considered, including Tcon recognition of specific low-efficiency self MHC-ligands, Treg recognition of intermediate-efficiency agonistic self MHC-ligands, and Tcon recognition of cross-reactive high-efficiency agonistic foreign MHC-ligands. These respective zones of TCR recognition efficiency are key to understanding how tissue-resident immune networks integrate the antigenic complexity of local environments to provide adaptive decisions setting the balance of suppressive and immunogenic responses. Importantly, deficiencies in the Treg repertoire appear to be an important cause of chronic inflammatory disease. Deficiencies may include global deficiencies in Treg numbers or function, subtle 'holes in the Treg repertoire' in tissue-resident Treg populations, or simply Treg insufficiencies that are unable to counter an overwhelming molecular mimicry stimulus. Tolerogenic vaccination and Treg-based immunotherapy are two therapeutic modalities meant to restore dominance of Treg networks to reverse chronic inflammatory disease. Studies of these therapeutic modalities in a preclinical setting have provided insight into the Treg niche, including the concept that intermediate-efficiency TCR signaling, high IFN-β concentrations, and low IL-2 concentrations favor Treg responses and active dominant mechanisms of immune tolerance. Overall, the purpose here is to assimilate new and established concepts regarding how cognate TCR specificity of the Treg repertoire and the contingent cytokine networks provide a foundation for understanding Treg suppressive strategy.

L-Arginine Modulates Neonatal Leukocyte Recruitment in a Gestational Age-Dependent Manner

(1) Background: L-arginine is a complex modulator of immune functions, and its levels are known to decrease under septic conditions. L-arginine may suppress leukocyte recruitment in vivo; however, little is known about the gestational age-specific effects of L-arginine on leukocyte recruitment in preterm infants. We now asked whether L-arginine alters leukocyte recruitment in preterm and term neonates. (2) Methods: Leukocytes were isolated from preterm (28 + 0 to 32 + 6 weeks of gestation) and term (>37 weeks of gestation) newborns as well as from healthy adults. After incubation with 10 µg/mL L-arginine, we assessed leukocyte rolling and adhesion in dynamic microflow chamber experiments and leukocyte transmigration in fluorescence assays. In addition, we measured the expression of inducible nitric oxide synthase (iNOS) and Arginase 1 (Arg-1) in neutrophils by flow cytometry. (3) Results: Leukocyte rolling, adhesion, and transmigration increased with gestational age. Leukocyte rolling, adhesion, and transmigration were decreased by L-arginine in term-born infants and adults. Preterm leukocytes showed no change in recruitment upon L-arginine exposure. Leukocyte adhesion after L-arginine exposure reached similar levels among all groups. In line, the expression of iNOS and Arg-1 was similar in all three age groups. (4) Conclusion: L-arginine dampens the ex vivo recruitment capacity of leukocytes from term-born infants, whereas no effect was seen in premature infants. As levels of iNOS and Arg-1 in neutrophils remain ontogenetically unchanged, the anti-inflammatory effect of L-arginine on the leukocyte recruitment cascade needs further investigation. These results add to the controversial debate of L-arginine supplementation in premature infants in sepsis.

Melanoma Peptide MHC Specific TCR Expressing T-Cell Membrane Camouflaged PLGA Nanoparticles for Treatment of Melanoma Skin Cancer

Melanoma is one of the most aggressive skin cancers, and the American Cancer Society reports that every hour, one person dies from melanoma. While there are a number of treatments currently available for melanoma (e.g., surgery, chemotherapy, immunotherapy, and radiation therapy), they face several problems including inadequate response rates, high toxicity, severe side effects due to non-specific targeting of anti-cancer drugs, and the development of multidrug resistance during prolonged treatment. To improve chemo-drug therapeutic efficiency and overcome these mentioned limitations, a multifunctional nanoparticle has been developed to effectively target and treat melanoma. Specifically, poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) were coated with a cellular membrane derived from the T cell hybridoma, 19LF6 endowed with a melanoma-specific anti-gp100/HLA-A2 T-cell receptor (TCR) and loaded with an FDA-approved melanoma chemotherapeutic drug Trametinib. T-cell membrane camouflaged Trametinib loaded PLGA NPs displayed high stability, hemo- and cyto-compatibility. They also demonstrated membrane coating dependent drug release profiles with the most sustained release from the NPs proportional with the highest amount of membrane used. 19LF6 membrane-coated NPs produced a threefold increase in cellular uptake toward the melanoma cell line in vitro compared to that of the bare nanoparticle. Moreover, the binding kinetics and cellular uptake of these particles were shown to be membrane/TCR concentration-dependent. The in vitro cancer killing efficiencies of these NPs were significantly higher compared to other NP groups and aligned with binding and uptake characteristics. Particles with the higher membrane content (greater anti-gp100 TCR content) were shown to be more effective when compared to the free drug and negative controls. In vivo biodistribution studies displayed the theragnostic capabilities of these NPs with more than a twofold increase in the tumor retention compared to the uncoated and non-specific membrane coated groups. Based on these studies, these T-cell membrane coated NPs emerge as a potential theragnostic carrier for imaging and therapy applications associated with melanoma.

Lipopolysaccharide-Induced Vascular Inflammation Model on Microfluidic Chip

Inflammation is the initiation of defense of our body against harmful stimuli. Lipopolysaccharide (LPS), originating from outer membrane of Gram-negative bacteria, causes inflammation in the animal’s body and can develop several diseases. In order to study the inflammatory response to LPS of blood vessels in vitro, 2D models have been mainly used previously. In this study, a microfluidic device was used to investigate independent inflammatory response of endothelial cells by LPS and interaction of inflamed blood vessel with monocytic THP-1 cells. Firstly, the diffusion of LPS across the collagen gel into blood vessel was simulated using COMSOL. Then, inflammatory response to LPS in engineered blood vessel was confirmed by the expression of Intercellular Adhesion Molecule 1 (ICAM-1) and VE-cadherin of blood vessel, and THP-1 cell adhesion and migration assay. Upregulation of ICAM-1 and downregulation of VE-cadherin in an LPS-treated condition was observed compared to normal condition. In the THP-1 cell adhesion and migration assay, the number of adhered and trans-endothelial migrated THP-1 cells were not different between conditions. However, migration distance of THP-1 was longer in the LPS treatment condition. In conclusion, we recapitulated the inflammatory response of blood vessels and the interaction of THP-1 cells with blood vessels due to the diffusion of LPS.

What's in a prick? Vaccines and the cardiovascular system

Evidence suggests a crucial role for vaccines in cardiovascular disease, mediated not only by disease prevention but also by immunomodulatory effects. This review attempts to briefly present the effects of pathogens and vaccines on the cardiovascular system and potential mechanisms for the development of vaccines against cardiovascular diseases per se. Current epidemiological evidence regarding vaccine effectiveness in different categories of heart disease is discussed, as well as current international guidelines' recommendations. In summary, cardiologists should strive to promote vaccination against specific pathogens with proven beneficial effects on cardiovascular diseases.

Shuxuening injection facilitates neurofunctional recovery via down-regulation of G-CSF-mediated granulocyte adhesion and diapedesis pathway in a subacute stroke mouse model

Post-stroke neural damage is a serious health concern which does not yet have an effective treatment. We have shown previously that Shuxuening injection (SXNI), a Ginkgo biloba extract-based natural medicine, protects brain after an acute ischemic stroke, but its efficacy for post-stroke recovery is not known. This study was to investigate whether SXNI can improve the prognosis of stroke at a subacute phase. Mice with cerebral ischemia-reperfusion injury (CIRI) were established by middle cerebral artery occlusion (MCAO), and drugs or saline were injected by the tail vein every 12 h after reperfusion. The therapeutic effect of SXNI was evaluated by survival rate, modified neurologic severity scores (mNSS), open-field test, locomotive gait patterns, cerebral infarction volume, brain edema and histopathological changes. Subsequently, a combined method of RNA-seq and Ingenuity® Pathway Analysis (IPA) was performed to identify key targets and pathways of SXNI facilitating the prognosis of stroke in mouse brain. The results of the transcriptome analysis were verified by real time reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), western blot (WB) and immunohistochemistry (IHC). The experimental results showed that in the new subacute stroke model, SXNI markedly improves the survival rate, neurological and motor functions and histopathological changes, and significantly reduces cerebral infarction and edema volume. RNA-seq analysis of subacute stroke mice with or without SXNI (3 mL/kg) indicated 963 differentially expressed genes (DEGs) with a fold change ≥ 1.5 and a P-value ≤ 0.01. IPA analysis of DEGs showed that granulocyte adhesion and diapedesis ranked first in the pathway ranking, and the most critical gene regulated by SXNI was G-csf. Simultaneously, RT-PCR, ELISA, WB and IHC results demonstrated that SXNI not only obviously reduced the mRNA expression levels of key genes G-csf, Sele and Mac-1 in this pathway, but also significantly decreased the protein expression levels of G-CSF in serum and E-selectin and MAC-1 in brain tissues. In summary, our research suggested that SXNI can exert a remarkable neurofunctional therapeutic effect on stroke mice via down-regulating G-CSF to inhibit granulocyte adhesion and diapedesis. This study provides experimental evidence that SXNI may fulfill the need for stroke medicine targeting specifically at the recovery stage.

Vitamin D status influences transcriptional levels of RANKL and inflammatory biomarkers which are associated with activation of PBMC

Vitamin D status is involved in the risk of many chronic diseases including cancer, inflammatory and autoimmune disease. The RANK/RANKL/OPG system is also implicated in the orchestration of immune functions. We aimed to investigate the expression of RANKL, OPG and markers of inflammation and immune activation in peripheral blood mononuclear cells (PBMC) from healthy subjects with different 25(OH)D3 plasma levels. The 25(OH)D3 plasma concentrations were assessed by HPLC. The gene expression was evaluated by qRT-PCR. The expression of CYP27B1 was lower in subjects with 25(OH)D3 levels below 50 nmol/L (deficiency) than subjects with both insufficient and sufficient levels of 25(OH)D3. In subjects with deficiency, we observed the up-regulation of RANKL, TNF-α, IFN-γ, ICAM and LFA-1, and a reduction of the anti-inflammatory cytokines IL-13 and IL-4 in comparison to other subjects. Finally, we found a negative correlation between RANKL mRNA levels and 25(OH)D3 and between 25(OH)D3 and ICAM mRNA levels. A positive correlation between ICAM and RANKL was observed. Our results give evidence of the modulatory effects of circulating 25(OH)D3 levels on gene expression of biomarkers of immune activation in PBMC, suggesting the possible use of PBMC as ex-vivo model to characterize molecular mechanisms of immune/inflammatory response in hypovitaminosis conditions.

The Immunological Basis of Dry Eye Disease and Current Topical Treatment Options

Homeostasis of the lacrimal functional unit is needed to ensure a well-regulated ocular immune response comprising innate and adaptive phases. When the ocular immune system is excessively stimulated and/or immunoregulatory mechanisms are disrupted, the balance between innate and adaptive phases is dysregulated and chronic ocular surface inflammation can result, leading to chronic dry eye disease (DED). According to the Tear Film and Ocular Surface Society Dry Eye Workshop II definition, DED is a multifactorial disorder of the ocular surface characterized by impairment and loss of tear homeostasis (hyperosmolarity), ocular discomfort or pain, and neurosensory abnormalities. Dysregulated ocular immune responses result in ocular surface damage, which is a further contributing factor to DED pathology. Several therapeutics are available to break the vicious circle of DED and prevent chronic disease and progression, including immunosuppressive agents (steroids) and immunomodulators (cyclosporine and lifitegrast). Given the chronic inflammatory nature of DED, each of these agents is commonly used in clinical practice. In this study, we review the immunopathology of DED and the molecular and cellular actions of current topical DED therapeutics to inform clinical decision making.

Whole-Genome Uterine Artery Transcriptome Profiling and Alternative Splicing Analysis in Rat Pregnancy

During pregnancy, the uterine artery (UA) undergoes extensive remodeling to permit a 20–40 fold increase in blood flow with associated changes in the expression of a multitude of genes. This study used next-gen RNA sequencing technology to identify pathways and genes potentially involved in arterial adaptations in pregnant rat UA (gestation day 20) compared with non-pregnant rat UA (diestrus). A total of 2245 genes were differentially expressed, with 1257 up-regulated and 970 down-regulated in pregnant UA. Gene clustering analysis revealed a unique cluster of suppressed genes implicated in calcium signaling pathway and vascular smooth muscle contraction in pregnant UA. Transcription factor binding site motif scanning identified C2H2 ZF, AP-2 and CxxC as likely factors functional on the promoters of down-regulated genes involved in calcium signaling and vascular smooth muscle contraction. In addition, 1686 genes exhibited alternative splicing that were mainly implicated in microtubule organization and smooth muscle contraction. Cross-comparison analysis identified novel genes that were both differentially expressed and alternatively spliced; these were involved in leukocyte and B cell biology and lipid metabolism. In conclusion, this first comprehensive study provides a valuable resource for understanding the molecular mechanism underlying gestational uterine arterial adaptations during pregnancy.

Nanosponges of circulating tumor-derived exosomes for breast cancer metastasis inhibition

Breast cancer contributes to high mortality rates as a result of metastasis. Tumor-derived exosomes facilitate the development of the premetastatic environment, interacting and inhibiting the normal function of immune cells, thereby forming an immunosuppressive microenvironment for tumor metastasis. Herein, the platelet and neutrophil hybrid cell membrane (PNM) was embellished on a gold nanocage (AuNC) surface called nanosponges and nanokillers (NSKs). NSKs can simultaneously capture and clear the circulating tumor cells (CTCs) and tumor-derived exosomes via high-affinity membrane adhesion receptors, effectively cutting off the connection between exosomes and immune cells. Bionic NSK is loaded with doxorubicin (DOX) and indocyanine green (ICG) for synergic chemo-photothermal therapy. NSKs show greater cellular uptake, deeper tumor penetration, and higher cytotoxicity to tumor cells in comparison to non-coated AuNCs or single-coated AuNCs in vitro. In vivo, the multipurpose NSKs could not only completely ablate the primary tumor but also inhibit breast cancer metastasis with high efficiency in xenograft and orthotopic breast tumor-bearing models. Thus, NSKs could be a promising nanomedicine for the future clinical intervention of breast cancer metastasis.

β2 Integrins-Multi-Functional Leukocyte Receptors in Health and Disease

β2 integrins are heterodimeric surface receptors composed of a variable α (CD11a-CD11d) and a constant β (CD18) subunit and are specifically expressed by leukocytes. The α subunit defines the individual functional properties of the corresponding β2 integrin, but all β2 integrins show functional overlap. They mediate adhesion to other cells and to components of the extracellular matrix (ECM), orchestrate uptake of extracellular material like complement-opsonized pathogens, control cytoskeletal organization, and modulate cell signaling. This review aims to delineate the tremendous role of β2 integrins for immune functions as exemplified by the phenotype of LAD-I (leukocyte adhesion deficiency 1) patients that suffer from strong recurrent infections. These immune defects have been largely attributed to impaired migratory and phagocytic properties of polymorphonuclear granulocytes. The molecular base for this inherited disease is a functional impairment of β2 integrins due to mutations within the CD18 gene. LAD-I patients are also predisposed for autoimmune diseases. In agreement, polymorphisms within the CD11b gene have been associated with autoimmunity. Consequently, β2 integrins have received growing interest as targets in the treatment of autoimmune diseases. Moreover, β2 integrin activity on leukocytes has been implicated in tumor development.

Upon microbial challenge, human neutrophils undergo rapid changes in nuclear architecture and chromatin folding to orchestrate an immediate inflammatory gene program

Differentiating neutrophils undergo large-scale changes in nuclear morphology. How such alterations in structure are established and modulated upon exposure to microbial agents is largely unknown. Here, we found that prior to encounter with bacteria, an armamentarium of inflammatory genes was positioned in a transcriptionally passive environment suppressing premature transcriptional activation. Upon microbial exposure, however, human neutrophils rapidly (<3 h) repositioned the ensemble of proinflammatory genes toward the transcriptionally permissive compartment. We show that the repositioning of genes was closely associated with the swift recruitment of cohesin across the inflammatory enhancer landscape, permitting an immediate transcriptional response upon bacterial exposure. We found that activated enhancers, marked by increased deposition of H3K27Ac, were highly enriched for cistromic elements associated with PU.1, CEBPB, TFE3, JUN, and FOSL2 occupancy. These data reveal how upon microbial challenge the cohesin machinery is recruited to an activated enhancer repertoire to instruct changes in chromatin folding, nuclear architecture, and to activate an inflammatory gene program.

Expression and Function of Host Defense Peptides at Inflammation Sites

There is a growing interest in the complex role of host defense peptides (HDPs) in the pathophysiology of several immune-mediated inflammatory diseases. The physicochemical properties and selective interaction of HDPs with various receptors define their immunomodulatory effects. However, it is quite challenging to understand their function because some HDPs play opposing pro-inflammatory and anti-inflammatory roles, depending on their expression level within the site of inflammation. While it is known that HDPs maintain constitutive host protection against invading microorganisms, the inducible nature of HDPs in various cells and tissues is an important aspect of the molecular events of inflammation. This review outlines the biological functions and emerging roles of HDPs in different inflammatory conditions. We further discuss the current data on the clinical relevance of impaired HDPs expression in inflammation and selected diseases.

Megakaryocyte emperipolesis: a new frontier in cell-in-cell interaction

Histology of bone marrow routinely identifies megakaryocytes that enclose neutrophils and other hematopoietic cells, a phenomenon termed emperipolesis. Preserved across mammalian species and enhanced with systemic inflammation and platelet demand, the nature and significance of emperipolesis remain largely unexplored. Recent advances demonstrate that emperipolesis is in fact a distinct form of cell-in-cell interaction. Following integrin-mediated attachment, megakaryocytes and neutrophils both actively drive entry via cytoskeletal rearrangement. Neutrophils enter a vacuole termed the emperisome which then releases them directly into the megakaryocyte cytoplasm. From this surprising location, neutrophils fuse with the demarcation membrane system to pass membrane to circulating platelets, enhancing the efficiency of thrombocytogenesis. Neutrophils then egress intact, carrying megakaryocyte membrane and potentially other cell components along with them. In this review, we summarize what is known about this intriguing cell-in-cell interaction and discuss potential roles for emperipolesis in megakaryocyte, platelet and neutrophil biology.

Impact of polyphenols in phagocyte functions

Polyphenols are a broad group of substances with potential health benefits found in plant species. Several of these compounds are capable of influencing the activation of intracellular signaling pathways, such as NF-kB, MAPK and JAK-STAT, responsible for the production of various inflammatory mediators such as tumor necrosis factor α (TNF-α) and interleukin 1 beta (IL-1β) and 12 (IL-12), enzymes involved in the production of reactive species such as inducible nitric oxide synthase (iNOS) and superoxide dehydrogenase (SOD), as well as enzymes involved in the production of eicosanoids, such as cyclooxygenase (COX) and lipoxygenase (LO). There is increased interest in the use of polyphenol-rich foods because of their immunomodulatory effect; however, the mechanisms used during macrophage responses are extremely complex and little is known about the effects of polyphenols on these cells. As such, this review summarizes the current view of polyphenol influences on macrophages.

Human Neutrophils Will Crawl Upstream on ICAM-1 If Mac-1 Is Blocked

The recruitment of neutrophils to sites of inflammatory insult is a hallmark of the innate immune response. Neutrophil recruitment is regulated by a multistep process that includes cell rolling, activation, adhesion, and transmigration through the endothelium commonly referred to as the leukocyte adhesion cascade. After selectin-mediated braking, neutrophils migrate along the activated vascular endothelium on which ligands, including intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), are expressed. Previous studies have shown that two cells that commonly home from blood vessel to tissue-T cells and hematopoietic stem and progenitor cells-use the integrin lymphocyte functional antigen-1 (LFA-1) to migrate against the direction of shear flow once adherent on ICAM-1 surfaces. Like T cells and hematopoietic stem and progenitor cells, neutrophils express LFA-1, but they also express macrophage-1 antigen (Mac-1), which binds to ICAM-1. Previous reports have shown that neutrophils will not migrate against the direction of flow on ICAM-1, but we hypothesized this was due to the influence of Mac-1. Here, we report that both the HL-60 neutrophil-like cell line and primary human neutrophils can migrate against the direction of fluid flow on ICAM-1 surfaces via LFA-1 if Mac-1 is blocked; otherwise, they migrate downstream. We demonstrate this both on ICAM-1 surfaces and on activated endothelium. In sum, both LFA-1 and Mac-1 binding ICAM-1 play a critical role in determining the direction of neutrophil migration along the endothelium, and their interaction may play an important role in controlling neutrophil trafficking during inflammation.

Complement activation on neutrophils initiates endothelial adhesion and extravasation

Neutrophils are essential to the pathogenesis of many inflammatory diseases. In the autoantibody-mediated K/BxN model of inflammatory arthritis, the alternative pathway (AP) of complement and Fc gamma receptors (FcγRs) are required for disease development while the classical pathway is dispensable. The reason for this differential requirement is unknown. We show that within minutes of K/BxN serum injection complement activation (CA) is detected on circulating neutrophils, as evidenced by cell surface C3 fragment deposition. CA requires the AP factor B and FcγRs but not C4, implying that engagement of FcγRs by autoantibody or immune complexes directly triggers AP C3 convertase assembly. The absence of C5 does not prevent CA on neutrophils but diminishes the upregulation of adhesion molecules. In vivo two-photon microscopy reveals that CA on neutrophils is critical for neutrophil extravasation and generation of C5a at the site of inflammation. C5a stimulates the release of neutrophil proteases, which contribute to the degradation of VE-cadherin, an adherens junction protein that regulates endothelial barrier integrity. C5a receptor antagonism blocks the extracellular release of neutrophil proteases, suppressing VE-cadherin degradation and neutrophil transendothelial migration in vivo. These results elucidate the AP-dependent intravascular neutrophil-endothelial interactions that initiate the inflammatory cascade in this disease model but may be generalizable to neutrophil extravasation in other inflammatory processes.

Therapeutic Targeting of Neutrophil Granulocytes in Inflammatory Liver Disease

Neutrophil granulocytes are the most numerous type of leukocyte in humans bearing an enormous, yet largely unexplored therapeutic potential. Scientists have very recently increased their efforts to study and understand these cells which contribute to various types of inflammatory diseases and cancer. The mechanisms that regulate neutrophil recruitment to inflamed tissues and neutrophil cytotoxic activities against host tissues and pathogens require more attention. The reactive oxygen species (ROS) are a popular source of cellular stress and organ injury, and are critically expressed by neutrophils. By combating pathogens using molecular combat factors such as neutrophil extracellular traps (NETs), these are immobilized and killed i.e., by ROS. NETs and ROS are essential for the immune defense, but upon excessive activation, may also harm healthy tissue. Thus, exploring new routes for modulating their migration and activation is highly desired for creating novel anti-inflammatory treatment options. Leukocyte transmigration represents a key process for inflammatory cell infiltration to injury sites. In this review, we briefly summarize the differentiation and roles of neutrophils, with a spotlight on intravital imaging. We further discuss the potential of nanomedicines, i.e., selectin mimetics to target cell migration and influence liver disease outcome in animal models. Novel perspectives further arise from formulations of the wide array of options of small non-coding RNA such as small interfering RNA (siRNA) and micro-RNA (miR) which exhibit enzymatic functions: while siRNA binds and degrades a single mRNA based on full complementarity of binding, miR can up and down-regulate multiple targets in gene transcription and translation, mediated by partial complementarity of binding. Notably, miR is known to regulate at least 60% of the protein-coding genes and thus includes a potent strategy for a large number of targets in neutrophils. Nanomedicines can combine properties of different drugs in a single formulation, i.e., combining surface functionalization with ligands and drug delivery. Inevitably, nanomedicines accumulate in other phagocytes, a fact that should be controlled for every novel formulation to restrain activation of macrophages or modifications of the immunological synapse. Controlled drug release enabled by nanotechnological delivery systems may advance the options of modulating neutrophil activation and migration.

Characterization of Aspergillus fumigatus Extracellular Vesicles and Their Effects on Macrophages and Neutrophils Functions

Extracellular vesicles (EVs) has been considered an alternative process for intercellular communication. EVs release by filamentous fungi and the role of vesicular secretion during fungus-host cells interaction remain unknown. Here, we identified the secretion of EVs from the pathogenic filamentous fungus, Aspergillus fumigatus. Analysis of the structure of EVs demonstrated that A. fumigatus produces round shaped bilayer structures ranging from 100 to 200 nm size, containing ergosterol and a myriad of proteins involved in REDOX, cell wall remodeling and metabolic functions of the fungus. We demonstrated that macrophages can phagocytose A. fumigatus EVs. Phagocytic cells, stimulated with EVs, increased fungal clearance after A. fumigatus conidia challenge. EVs were also able to induce the production of TNF-α and CCL2 by macrophages and a synergistic effect was observed in the production of these mediators when the cells were challenged with the conidia. In bone marrow-derived neutrophils (BMDN) treated with EVs, there was enhancement of the production of TNF-α and IL-1β in response to conidia. Together, our results demonstrate, for the first time, that A. fumigatus produces EVs containing a diverse set of proteins involved in fungal physiology and virulence. Moreover, EVs are biologically active and stimulate production of inflammatory mediators and fungal clearance.

Using Yoda-1 to mimic laminar flow in vitro: A tool to simplify drug testing

The endothelium is an attractive drug target and an important site of adverse drug reactions. Endothelial dysfunction is strongly associated with inflammation and contributes to drug-induced cardiovascular toxicity. Endothelial cells in the circulation are exposed to haemodynamic forces including shear stress. Including shear stress may improve future endothelial cell drug discovery or toxicity screening. Piezo-1 is required for endothelial cells to respond to shear stress. In this study, we investigated whether a small molecule activator of Piezo-1, Yoda-1, can mimic the effect of laminar flow-induced shear stress on endothelial cell inflammation, and endothelial cytotoxicity in response to the chemotherapy agent, doxorubicin.

First, we tested whether Yoda-1 could mimic the effects of shear stress of expression of the endothelial adhesion molecules, ICAM-1 and VCAM-1. Human umbilical vein endothelial cells (HUVEC) were cultured in static conditions (with or without Yoda-1) or under laminar flow-induced shear stress (5 dyn/cm²). Yoda-1 and laminar flow had similar anti-inflammatory effects, reducing the ability of TNF-α to induce ICAM-1 and VCAM-1 expression. We then tested whether Yoda-1 could mimic the effect of shear stress on doxorubicin-induced cytotoxicity. Both laminar flow and Yoda-1 treatment of static cultures increased the cytotoxicity of doxorubicin. These findings show that Piezo-1 activation with Yoda-1 in static culture leads to an endothelial cell phenotype that mimics endothelial cells under laminar flow. Pharmacological activation of Piezo-1 may be a useful approach to mimic constant shear stress in static cultures, which may improve endothelial drug discovery and toxicity testing.