A synthetic bioactive peptide of the C-terminal fragment of adhesion protein Fibulin7 attenuates the inflammatory functions of innate immune cells in LPS-induced systemic inflammation.

OBJECTIVE: Systemic inflammation is associated with improper localization of hyperactive neutrophils and monocytes in visceral organs. Previously, a C-terminal fragment of adhesion protein Fibulin7 (Fbln7-C) was shown to regulate innate immune functionality during inflammation. Recently, a shorter bioactive peptide of Fbln7-C, FC-10, via integrin binding was shown to reduce ocular angiogenesis. However, the role of FC-10 in regulating the neutrophils and monocyte functionality during systemic inflammatory conditions is unknown. The study sought to explore the role of FC-10 peptide on the functionality of innate immune cells during inflammation and endotoxemic mice. METHODS: Neutrophils and monocytes were isolated from healthy donors and septic patient clinical samples and Cell adhesion assay was performed using a UV spectrophotometer. Gene expression studies were performed using qPCR. Protein level expression was measured using ELISA and flow cytometry. ROS assay, and activation markers analysis in vitro, and in vivo were done using flow cytometry. TREATMENT: Cells were stimulated with LPS (100 ng/mL) and studied in the presence of peptides (10 µg, and 20 µg/mL) in vitro. In an in vivo study, mice were administered with LPS (36.8 mg/kg bw) and peptide (20 µg). RESULTS: This study demonstrates that human neutrophils and monocytes adhere to FC-10 via integrin ß1, inhibit spreading, ROS, surface activation markers (CD44, CD69), phosphorylated Src kinase, pro-inflammatory genes, and protein expression, compared to scrambled peptide in cells isolated from healthy donors and clinical sample. In line with the in vitro data, FC-10 (20 µg) administration significantly decreases innate cell infiltration at inflammatory sites, improves survival in endotoxemia animals & reduces the inflammatory properties of neutrophils and monocytes isolated from septic patients. CONCLUSION: FC-10 peptide can regulate neutrophils and monocyte functions and has potential to be used as an immunomodulatory therapeutic in inflammatory diseases.

Monocytes and macrophages: Origin, homing, differentiation, and functionality during inflammation.

Monocytes and macrophages are essential components of innate immune system and have versatile roles in homeostasis and immunity. These phenotypically distinguishable mononuclear phagocytes play distinct roles in different stages, contributing to the pathophysiology in various forms making them a potentially attractive therapeutic target in inflammatory conditions. Several pieces of evidence have supported the role of different cell surface receptors expressed on these cells and their downstream signaling molecules in initiating and perpetuating the inflammatory response. In this review, we discuss the current understanding of the monocyte and macrophage biology in inflammation, highlighting the role of chemoattractants, inflammasomes, and integrins in the function of monocytes and macrophages during events of inflammation. This review also covers the recent therapeutic interventions targeting these mononuclear phagocytes at the cellular and molecular levels.

Role of RhoG as a regulator of cellular functions: integrating insights on immune cell activation, migration, and functions.

BACKGROUND: RhoG is a multifaceted member of the Rho family of small GTPases, sharing the highest sequence identity with the Rac subfamily members. It acts as a molecular switch, when activated, plays a central role in regulating the fundamental processes in immune cells, such as actin-cytoskeleton dynamics, transendothelial migration, survival, and proliferation, including immunological functions (e.g., phagocytosis and trogocytosis) during inflammatory responses. METHOD: We have performed a literature review based on published original and review articles encompassing the significant effect of RhoG on immune cell functions from central databases, including PubMed and Google Scholar. RESULTS AND CONCLUSIONS: Recently published data shows that the dynamic expression of different transcription factors, non-coding RNAs, and the spatiotemporal coordination of different GEFs with their downstream effector molecules regulates the cascade of Rho signaling in immune cells. Additionally, alterations in RhoG-specific signaling can lead to physiological, pathological, and developmental adversities. Several mutations and RhoG-modulating factors are also known to pre-dispose the downstream signaling with abnormal gene expression linked to multiple diseases. This review focuses on the cellular functions of RhoG, interconnecting different signaling pathways, and speculates the importance of this small GTPase as a prospective target against several pathological conditions.

In silico identification and characterization of small-molecule inhibitors specific to RhoG/Rac1 signaling pathway.

Rho family GTPases serve as molecular switches in numerous cellular processes, and their overexpression is involved in disease conditions. RhoG is one of the less explored Rho GTPases with significant sequential and structural homology with Rac1. Experimental mutations in RhoG (i.e., RhoGG12V and RhoGQ61L) are shown to dysregulate cell migration. Thus, targeting upstream activators of RhoG, such as guanine nucleotide exchange factors (GEFs), maybe an important strategy for inhibiting RhoG activation. In the current study, we have modelled the 3D structure of RhoG with greater accuracy as confirmed through PROCHECK, ProSA, and Verify3D. Our results indicate that 90.4% of residues are in the Ramachandran plots favoured region, with the Z-score of -6.46, and 87.96% of residues had an averaged 3D-1D score ≥0.2. Further, we have evaluated and binding dynamics of ten Rac1 inhibitors to investigate their potential to inhibit RhoG by targeting GEFs binding grooves. To this end, the binding energy of the docked complexes of the wild-type (WT) RhoG and its mutant proteins with inhibitor molecules was calculated using the MM/PBSA method. Our results from docking studies showed that macrolide1 binds efficiently with the GEF site of WT RhoG and the mutants mentioned above. However, an extensive analysis using MD simulations (200 ns) showed that the Rac1 based inhibitor, EHop-016, and NSC23766 might bind with greater affinity to GEF sites of mutants and WT RhoG. Thus, the results from the study indicate that Rac1 inhibitors have the potential for use as therapeutics in conditions involving dysregulation of RhoG.Communicated by Ramaswamy H. Sarma.

Inflammation driven metabolic regulation and adaptation in macrophages.

Macrophages are a diverse population of phagocytic immune cells involved in the host defense mechanisms and regulation of homeostasis. Usually, macrophages maintain healthy functioning at the cellular level, but external perturbation in their balanced functions can lead to acute and chronic disease conditions. By sensing the cues from the tissue microenvironment, these phagocytes adopt a plethora of phenotypes, such as inflammatory or M1 to anti-inflammatory (immunosuppressive) or M2 subtypes, to fulfill their spectral range of functions. The existing evidence in the literature supports that in macrophages, regulation of metabolic switches and metabolic adaptations are associated with their functional behaviors under various physiological and pathological conditions. Since these macrophages play a crucial role in many disorders, therefore it is necessary to understand their heterogeneity and metabolic reprogramming. Consequently, these macrophages have also emerged as a promising target for diseases in which their role is crucial in driving the disease pathology and outcome (e.g., Cancers). In this review, we discuss the recent findings that link many metabolites with macrophage functions and highlight how this metabolic reprogramming can improve our understanding of cellular malfunction in the macrophages during inflammatory disorders. A systematic analysis of the interconnecting crosstalk between metabolic pathways with macrophages should inform the selection of immunomodulatory therapies for inflammatory diseases.

Yoga and meditation, an essential tool to alleviate stress and enhance immunity to emerging infections: A perspective on the effect of COVID-19 pandemic on students.

The COVID-19 pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has negatively impacted the global healthcare and economic systems worldwide. The COVID-19 pandemic has also created an emotional and psychological pandemic among people of all ages irrespective of economic status and physical wellbeing. As a consequence of prolonged lockdowns, one of the most severely affected age groups globally is the young adults' group, especially students. Uncertainties in the academic calendar, restricted outdoor activities, and unusual daily routines during lockdowns led to higher incidences of stress, anxiety, and depression among students worldwide. In this review, we summarise the available evidence on the effect of lockdowns on students and discuss possible positive impacts of yoga and meditation on various psychological, emotional, and immunological parameters, which can significantly influence the general wellbeing and academic performance of students. Perspectives shared in the review will also bring awareness on how yoga and meditation could boost students' performance and assist them in maintaining physical and mental wellbeing during stressful conditions such as future epidemics and pandemics with novel infections. This information could help create better educational curriculums and healthy routines for students.

Did Climate Change Influence the Emergence, Transmission, and Expression of the COVID-19 Pandemic?

The human race has survived many epidemics and pandemics that have emerged and reemerged throughout history. The novel coronavirus Severe Acute Respiratory Syndrome SARS-CoV-2/COVID-19 is the latest pandemic and this has caused major health and socioeconomic problems in almost all communities of the world. The origin of the virus is still in dispute but most likely, the virus emerged from the bats and also may involve an intermediate host before affecting humans. Several other factors also may have affected the emergence and outcome of the infection but in this review, we make a case for a possible role of climate change. The rise in industrialization-related human activities has created a marked imbalance in the homeostasis of environmental factors such as temperature and other weather and these might even have imposed conditions for the emergence of future coronavirus cycles. An attempt is made in this review to explore the effect of ongoing climate changes and discuss if these changes had a role in facilitating the emergence, transmission, and even the expression of the COVID-19 pandemic. We surmise that pandemics will be more frequent in the future and more severely impactful unless climate changes are mitigated.

Inflammatory Monocytes and Subsets of Macrophages with Distinct Surface Phenotype Correlate with Specific Integrin Expression Profile during Murine Sepsis.

Monocytes and macrophages participate in both pro- and anti-inflammatory responses during sepsis. Integrins are the cell adhesion receptors that mediate leukocyte migration and functions. To date, it is not known whether integrin profiles correlate with their trafficking, differentiation, and polarization during sepsis. In this study, using endotoxemia and cecal ligation and puncture model of murine sepsis, we have analyzed the role of surface integrins in tissue-specific infiltration, distribution of monocytes and macrophages, and their association with inflammation-induced phenotypic and functional alterations postinduction (p.i.) of sepsis. Our data show that Ly-6Chi inflammatory monocytes infiltrated into the peritoneum from blood and bone marrow within a few hours p.i. of sepsis, with differential distribution of small (Ly-6CloCD11bloF4/80lo) and large peritoneal macrophages (Ly-6CloCD11bhiF4/80hi) in both models. The results from flow cytometry studies demonstrated a higher expression of integrin α4ß1 on the Ly-6Chi monocytes in different tissues, whereas macrophages in the peritoneum and lungs expressed higher levels of integrin α5ß1 and αvß3 in both models. Additionally, F4/80+ cells with CD206hiMHCIIlo phenotype increased in the lungs of both models by six hours p.i. and expressed higher levels of integrin αvß3 in both lungs and peritoneum. The presence of such cells correlated with higher levels of IL-10 and lower levels of IL-6 and IL-1ß transcripts within six hours p.i. in the lungs compared with the mesentery. Furthermore, bioinformatic analysis with its experimental validation revealed an association of integrin α4 and α5 with inflammatory (e.g., p-SRC) and integrin αv with regulatory molecules (e.g., TGFBR1) in macrophages during sepsis.

Functional and Therapeutic Relevance of Rho GTPases in Innate Immune Cell Migration and Function during Inflammation: An In Silico Perspective.

Systematic regulation of leukocyte migration to the site of infection is a vital step during immunological responses. Improper migration and localization of immune cells could be associated with disease pathology as seen in systemic inflammation. Rho GTPases act as molecular switches during inflammatory cell migration by cycling between Rho-GDP (inactive) to Rho-GTP (active) forms and play an essential role in the precise regulation of actin cytoskeletal dynamics as well as other immunological functions of leukocytes. Available reports suggest that the dysregulation of Rho GTPase signaling is associated with various inflammatory diseases ranging from mild to life-threatening conditions. Therefore, it is crucial to understand the step-by-step activation and inactivation of GTPases and the functioning of different Guanine Nucleotide Exchange Factors (GEFs) and GTPase-Activating Proteins (GAPs) that regulate the conversion of GDP to GTP and GTP to GDP exchange reactions, respectively. Here, we describe the molecular organization and activation of various domains of crucial elements associated with the activation of Rho GTPases using solved PDB structures. We will also present the latest evidence available on the relevance of Rho GTPases in the migration and function of innate immune cells during inflammation. This knowledge will help scientists design promising drug candidates against the Rho-GTPase-centric regulatory molecules regulating inflammatory cell migration.

Climate change: how it impacts the emergence, transmission, resistance and consequences of viral infections in animals and plants.

The ongoing COVID-19 pandemic has made us wonder what led to its occurrence and what can be done to avoid such events in the future. As we document, one changing circumstance that is resulting in the emergence and changing the expression of viral diseases in both plants and animals is climate change. Of note, the rapidly changing environment and weather conditions such as excessive flooding, droughts, and forest fires have raised concerns about the global ecosystem's security, sustainability, and balance. In this review, we discuss the main consequences of climate change and link these to how they impact the appearance of new viral pathogens, how they may facilitate transmission between usual and novel hosts, and how they may also affect the host's ability to manage the infection. We emphasize how changes in temperature and humidity and other events associated with climate change influence the reservoirs of viral infections, their transmission by insects and other intermediates, their survival outside the host as well the success of infection in plants and animals. We conclude that climate change has mainly detrimental consequences for the emergence, transmission, and outcome of viral infections and plead the case for halting and hopefully reversing this dangerous event.

A C-terminal fragment of adhesion protein fibulin-7 inhibits growth of murine breast tumor by regulating macrophage reprogramming.

Recent reports have shown that a C-terminal fragment of adhesion protein Fibulin7 (Fbln7-C) could demonstrate both antiangiogenic and anti-inflammatory activities. The current study investigated the potential of Fbln7-C as a modulator of tumor-associated macrophages (TAMs) and its potential as an anticancer therapeutic. Our in vitro data show that Fbln7-C could inhibit the tumor cell line (MDA-MB-231) supernatant-induced reprogramming of human monocytes into immunosuppressive TAMs as indicated by higher expression of pERK1/2 and pSTAT1 molecules, and reduced expression of CD206 protein and arg1, ido, and vegf transcripts in monocytes cultured in the presence of Fbln7-C compared to controls. Interestingly, Fbln7-C-treated macrophages retained their altered phenotype even after the removal of Fbln7-C, and their secretome demonstrated anticancer activities. Finally, in a 4T1-induced murine breast tumor model, intravenous administration of Fbln7-C, following the appearance of measurable tumors, significantly reduced the growth and weight of the tumors. Detailed phenotypic analysis of the infiltrated monocyte/macrophage populations (F480+ Ly6G- CD11b+ ) at day 23 postinduction showed a higher percentage of inflammatory monocytes (F480+ Ly6Chi CD11b+ ) and a delayed differentiation into anti-inflammatory TAMs as evident by their reduced levels of CD206 expression. In conclusion, the above data suggest that Fbln7-C could regulate the tumor environment-induced macrophage reprogramming and has the potential for cancer therapeutics.

The role of adhesion protein Fibulin7 in development and diseases.

Fibulins are a family of secreted glycoproteins, which play an important role in regulating multiple cellular functions such as adhesion, growth, motility, and survival. Fibulin7 (Fbln7) is expressed in developing odontoblasts, in the giant trophoblast layer of the placenta, in the choroid of the eyes as well as in the cartilage. Since its discovery, reports from various research groups have improved our understanding about the roles and effects of Fbln7 and Fbln7 derived fragments and peptides under physiological and pathological conditions such as tooth development, angiogenesis, immunoregulation, cancer pathogenesis and very recently as a possible biomarker for glaucoma. This review will highlight the latest developments in our understanding of the functions, the proposed mechanism of actions, and Fbln7's possible implications in future research and as therapeutics for different diseases.

A C-terminal fragment of adhesion protein Fibulin7 regulates neutrophil migration and functions and improves survival in LPS induced systemic inflammation.

Accumulation of hyperactive neutrophils in the visceral organs was shown to be associated with sepsis-induced multi-organ failure. Recently, a C-terminal fragment of secreted glycoprotein Fibulin7 (Fbln7-C) was shown to inhibit angiogenesis and regulate monocyte functions in inflammatory conditions. However, its effects on neutrophil functions and systemic inflammation induced lethality remain unknown. In this study, we show that human peripheral blood neutrophils adhered to Fbln7-C in a dose-dependent manner via integrin ß1. Moreover, the presence of Fbln7-C inhibited spreading, and fMLP mediated random migration of neutrophils on fibronectin. Significant reduction in ROS and inflammatory cytokine production (i.e., IL-6, IL-1ß) was observed, including a reduction in ERK1/2 phosphorylation in neutrophils stimulated with LPS and fMLP in the presence of Fbln7-C compared to untreated controls. In an in vivo model of endotoxemia, the administration of Fbln7-C (10 µg/dose) significantly improved survival and reduced the infiltration of neutrophils to the site of inflammation. Additionally, neutrophils infiltrating into the inflamed peritoneum of Fbln7-C administered animals expressed lower levels CD11b marker, IL-6, and produced lower levels of ROS upon stimulation with PMA compared to untreated controls. In conclusion, our results show that Fbln7-C could bind to the integrin ß1 on the neutrophil surface and regulate their inflammatory functions.

Electrostatic Surface Potential of Macrophages Correlates with Their Functional Phenotype.

Macrophages exist in various functional phenotypes, which could be identified by specific surface molecules. Previous studies have shown that modulation of surface charges could alter the phagocytic function of macrophages. In this study, we show that activation of both human peripheral blood monocyte and THP-1-derived macrophages with lipopolysaccharide (LPS) or IL-1ß resulted in a significant decrease in the zeta potential compared to freshly isolated monocytes and unstimulated macrophages. Interestingly, interaction with bacteria significantly increased the zeta potential of such cells irrespective of activation conditions. Similarly, IFNγ-treated pro-inflammatory macrophages showed lesser negative zeta potential compared to untreated control. A moderate reduction was also seen in IL-4-treated anti-inflammatory subtype. Additionally, in an LPS-induced systemic inflammation model, bone marrow cells isolated after 2 h of LPS injection showed significant reduction in zeta potential compared to naïve cells. Furthermore, electrostatic potential measurement of surface proteins associated with pro-inflammatory and anti-inflammatory macrophages, using in silico modeling under physiological and protonation conditions, showed that the average electrostatic potential of pro-inflammatory type surface proteins was less negative than anti-inflammatory subtype. These data suggest that the expression of different protein molecules on macrophages under different environments may contribute to the zeta potential and that this quick and low-cost technique could be used in monitoring macrophage functional phenotypes.

Characterization of difference in structure and function of fresh and mastitic bovine milk fat globules.

Characterization of milk fat globule (MFG) was performed to investigate the difference in MFG membrane (MFGM) between fresh and mastitis Holstein Friesian cow milk. Lipid distribution investigated by exogenous phospholipids using microscopy showed higher phospholipid content in fresh compared to mastitic MFGM. Xanthine oxidase assay indicative of membrane impairment revealed lower activity in mastitic samples compared to fresh globules. Of note, significantly higher roughness of globule surface and zeta potential was observed in mastitis compared to fresh globules. Influence of globule membrane on the interaction with L. fermentum demonstrated preferential adhesion of bacteria to fresh compared to mastitic globules including enhanced extent of binding. Results of the present study provides an insight of the interfacial changes occurring at the globule surface as well as highlighting the importance of selective bacterial interaction with milk components for the potential development of functional food with relevance to human health.

Investigation of Extracellular Matrix Protein Expression Dynamics Using Murine Models of Systemic Inflammation.

Extracellular matrix (ECM) proteins form the structural support for migration of leukocytes and provide multiple signals to assist in their functions during inflammatory conditions. Presence of pro-inflammatory mediators in the tissues results in the remodelling of matrices which could modify the functions of extravasated leukocytes. Previous reports have shown changes in the expression of ECM proteins during local inflammatory responses. In this study, we have investigated the time- and tissue-specific expression profile of key ECM proteins in systemic inflammation using lipopolysaccharide (LPS)-induced endotoxemia and cecal ligation and puncture (CLP) mouse models. The results show that compared to naïve tissues, within 12 h following CLP surgery, a 20-30-fold increase was observed in the expression of collagen-IV (Col-IV) transcripts in the mesentery tissues with a 2.4-fold increase in the protein by 24 h. However, Western blot band intensities indicated that vimentin and fibrinogen were remarkably expressed in more quantity compared to Col-IV. Secondly, in CLP group of mice, fibrinogen showed 6-40-fold increase in mRNA level in various tissues with about 2-fold increase in the protein level compared to respective naïve tissues. Similar studies in the LPS-injected mice showed up to 2-3 fold increase in the expression of Col-IV, fibrinogen and vimentin at protein level in the lungs. In such animals, although similar pattern was observed for fibrinogen in kidney and liver tissues, the mesentery showed prominent changes in Col-IV and vimentin mRNA compared to CLP. Further, bioinformatics analysis showed multiple pathways which could be associated with vimentin, Col-IV and fibrinogen under inflammatory conditions both in human and mouse. The current study will help in better understanding of possible signalling from ECM proteins in inflammatory microenvironment and may contribute in development of cell adhesion-based therapeutics.

Cell adhesion protein fibulin-7 and its C-terminal fragment negatively regulate monocyte and macrophage migration and functions in vitro and in vivo.

Fibulin-7 (Fbln7) has been identified as the latest member of the fibulin family of secreted glycoproteins in developing teeth, functioning as a cell adhesion molecule and interacting with other matrix proteins, receptors, and growth factors. More recently, we have shown that the C-terminal Fbln7 fragment (Fbln7-C) has antiangiogenic activity in vitro. Fbln7 is also expressed in immune-privileged tissues, such as eye and placenta, but its functional significance is unknown. In the current study, we show that human monocytes adhere to both full-length Fbln7 (Fbln7-FL) and Fbln7-C, in part, via integrins α5ß1 and α2ß1. Morphologic studies and surface expression analyses of CD14, mannose receptor (CD206), major histocompatibility complex II, and CD11b receptors revealed that both Fbln7-FL and Fbln7-C inhibit M-CSF-induced monocyte differentiation. Fbln7-C had significantly greater negative effects on cell spreading and stress fiber formation, including the production of IL-6 and metalloproteinase-1/-9 compared with Fbln7-FL. Furthermore, in an LPS-induced systemic inflammation model, Fbln7-C and Fbln7-FL reduced the infiltration of immune cells, such as neutrophils and macrophages, to the inflamed peritoneum. Thus, these results suggest that Fbln7 and Fbln7-C could modulate the activity of immune cells and have therapeutic potential for inflammatory diseases.-Sarangi, P. P., Chakraborty, P., Dash, S. P., Ikeuchi, T., de Vega, S., Ambatipudi, K., Wahl, L., Yamada, Y. Cell adhesion protein fibulin-7 and its C-terminal fragment negatively regulate monocyte and macrophage migration and functions in vitro and in vivo.

Activated Protein C Attenuates Severe Inflammation by Targeting VLA-3high Neutrophil Subpopulation in Mice.

The host injury involved in multiorgan system failure during severe inflammation is mediated, in part, by massive infiltration and sequestration of hyperactive neutrophils in the visceral organ. A recombinant form of human activated protein C (rhAPC) has shown cytoprotective and anti-inflammatory functions in some clinical and animal studies, but the direct mechanism is not fully understood. Recently, we reported that, during endotoxemia and severe polymicrobial peritonitis, integrin VLA-3 (CD49c/CD29) is specifically upregulated on hyperinflammatory neutrophils and that targeting the VLA-3high neutrophil subpopulation improved survival in mice. In this article, we report that rhAPC binds to human neutrophils via integrin VLA-3 (CD49c/CD29) with a higher affinity compared with other Arg-Gly-Asp binding integrins. Similarly, there is preferential binding of activated protein C (PC) to Gr1highCD11bhighVLA-3high cells isolated from the bone marrow of septic mice. Furthermore, specific binding of rhAPC to human neutrophils via VLA-3 was inhibited by an antagonistic peptide (LXY2). In addition, genetically modified mutant activated PC, with a high affinity for VLA-3, shows significantly improved binding to neutrophils compared with wild-type activated PC and significantly reduced neutrophil infiltration into the lungs of septic mice. These data indicate that variants of activated PC have a stronger affinity for integrin VLA-3, which reveals novel therapeutic possibilities.

Role of cellular events in the pathophysiology of sepsis.

INTRODUCTION: Sepsis is a dysregulated host immune response due to an uncontrolled infection. It is a leading cause of mortality in adult intensive care units globally. When the host immune response induced against a local infection fails to contain it locally, it progresses to sepsis, severe sepsis, septic shock and death. METHOD: Literature survey was performed on the roles of different innate and adaptive immune cells in the development and progression of sepsis. Additionally, the effects of septic changes on reprogramming of different immune cells were also summarized to prepare the manuscript. FINDINGS: Scientific evidences to date suggest that the loss of balance between inflammatory and anti-inflammatory responses results in reprogramming of immune cell activities that lead to irreversible tissue damaging events and multi-organ failure during sepsis. Many surface receptors expressed on immune cells at various stages of sepsis have been suggested as biomarkers for sepsis diagnosis. Various immunomodulatory therapeutics, which could improve the functions of immune cells during sepsis, were shown to restore immunological homeostasis and improve survival in animal models of sepsis. CONCLUSION: In-depth and comprehensive knowledge on the immune cell activities and their correlation with severity of sepsis will help clinicians and scientists to design effective immunomodulatory therapeutics for treating sepsis.

Sepsis lethality via exacerbated tissue infiltration and TLR-induced cytokine production by neutrophils is integrin α3ß1-dependent.

Integrin-mediated migration of neutrophils to infected tissue sites is vital for pathogen clearance and therefore host survival. Although ß2 integrins have been shown to mediate neutrophil transendothelial migration during systemic and local inflammation, relatively little information is available regarding neutrophil migration in sepsis beyond the endothelial cell layer. In this study, we report that integrin α3ß1 (VLA-3; CD49c/CD29) is dramatically upregulated on neutrophils isolated from both human septic patients and in mouse models of sepsis. Compared with the α3ß1 (low) granulocytes, α3ß1 (high) cells from septic animals displayed hyperinflammatory phenotypes. Administration of a α3ß1 blocking peptide and conditional deletion of α3 in granulocytes significantly reduced the number of extravasating neutrophils and improved survival in septic mice. In addition, expression of α3ß1 on neutrophils was associated with Toll-like receptor-induced inflammatory responses and cytokine productions. Thus, our results show that α3ß1 is a novel marker of tissue homing and hyperresponsive neutrophil subtypes in sepsis, and blocking of α3ß1 may represent a new therapeutic approach in sepsis treatment.