Tuftsin promotes an anti-inflammatory switch and attenuates symptoms in experimental autoimmune encephalomyelitis. PLoS One. 2012;7:e34933. [PMID: 22529957 PMCID: PMC3328491 DOI: 10.1371/journal.pone.0034933]

Combating bacterial infections with host defense peptides: Shifting focus from bacteria to host immunity

The increasing prevalence of multidrug-resistant bacterial infections necessitates the exploration of novel paradigms for anti-infective therapy. Antimicrobial peptides (AMPs), also known as host defense peptides (HDPs), have garnered extensive recognition as immunomodulatory molecules that leverage natural host mechanisms to enhance therapeutic benefits. The unique immune mechanism exhibited by certain HDPs that involves self-assembly into supramolecular nanonets capable of inducing bacterial agglutination and entrapping is significantly important. This process effectively prevents microbial invasion and subsequent dissemination and significantly mitigates selective pressure for the evolution of microbial resistance, highlighting the potential of HDP-based antimicrobial therapy. Recent advancements in this field have focused on developing bio-responsive materials in the form of supramolecular nanonets. A comprehensive overview of the immunomodulatory and bacteria-agglutinating activities of HDPs, along with a discussion on optimization strategies for synthetic derivatives, is presented in this article. These optimized derivatives exhibit improved biological properties and therapeutic potential, making them suitable for future clinical applications as effective anti-infective therapeutics.

The Pathological Activation of Microglia Is Modulated by Sexually Dimorphic Pathways

Microglia are the primary immunocompetent cells of the central nervous system (CNS). Their ability to survey, assess and respond to perturbations in their local environment is critical in their role of maintaining CNS homeostasis in health and disease. Microglia also have the capability of functioning in a heterogeneous manner depending on the nature of their local cues, as they can become activated on a spectrum from pro-inflammatory neurotoxic responses to anti-inflammatory protective responses. This review seeks to define the developmental and environmental cues that support microglial polarization towards these phenotypes, as well as discuss sexually dimorphic factors that can influence this process. Further, we describe a variety of CNS disorders including autoimmune disease, infection, and cancer that demonstrate disparities in disease severity or diagnosis rates between males and females, and posit that microglial sexual dimorphism underlies these differences. Understanding the mechanism behind differential CNS disease outcomes between men and women is crucial in the development of more effective targeted therapies.

Tuftsin ameliorates splenic inflammatory injury by promoting neuropilin-1 in severe acute pancreatitis

Severe acute pancreatitis (SAP)-associated spleen injury causing immune disturbances aggravates organs injuries, which contributes to higher mortality rate. However, there are no effective drugs to cure SAP-induced spleen injury. Here, we found that Tuftsin (TN) is effective for ameliorating SAP-induced pathological damage and inflammation of spleen, mainly via alleviating mitochondrial dysfunction, oxidative stress, ATP depletion and the expression of pro-inflammatory factors. We further found that TN promoted anti-inflammatory macrophage phenotype M2 via up-regulating NRP1 on macrophage in spleen during SAP. Meanwhile, EG00229 (an inhibitor of NRP1 bound to TN) weakened TN's therapeutic effect in SAP-associated spleen injury. And EG00229 also inhibited M2 macrophage, leading to increasing inflammasome formation. Additionally, EG00229 reduced the protective efficiency of TN on mitochondrial dysfunction, and inflammation injury via NRP1 in spleen caused by SAP. Similarly, siRNA-Nrp1 into macrophage also prevented TN's inhibition on apoptosis. These findings reveal that TN alleviates SAP-induced spleen injury by promoting NRP1.

2Receptor Specific Ligand conjugated Nanocarriers: an Effective Strategy for Targeted Therapy of Tuberculosis

Tuberculosis (TB) is an ancient chronic disease caused by the bacillus Mycobacterium tuberculosis, which has affected mankind for more than 4,000 years. Compliance with the standard conventional treatment can assure recovery from tuberculosis, but emergence of drug resistant strains pose a great challenge for effective management of tuberculosis. The process of discovery and development of new therapeutic entities with better specificity and efficacy is unpredictable and time consuming. Hence, delivery of pre-existing drugs with improved targetability is the need of the hour. Enhanced delivery and targetability can ascertain improved bioavailability, reduced toxicity, decreased frequency of dosing and therefore better patient compliance. Nanoformulations are being explored for effective delivery of therapeutic agents, however optimum specificity is not guaranteed. In order to achieve specificity, ligands specific to receptors or cellular components of macrophage and Mycobacteria can be conjugatedto nanocarriers. This approach can improve localization of existing drug molecules at the intramacrophageal site where the parasites reside, improve targeting to the unique cell wall structure of Mycobacterium or improve adhesion to epithelial surface of intestine or alveolar tissue (lectins). Present review focuses on the investigation of various ligands like Mannose, Mycolic acid, Lectin, Aptamers etc. installed nanocarriers that are being envisaged for targeting antitubercular drugs.

Mycobacterium tuberculosis Rv2626c-derived peptide as a therapeutic agent for sepsis

The Rv2626c protein of Mycobacterium tuberculosis is a promising vaccine candidate owing to its strong serum antibody response in patients with tuberculosis. However, there is limited information regarding the intracellular response induced by Rv2626c in macrophages. In this study, we demonstrated that Rv2626c interacts with the RING domain of TRAF6 and inhibits lysine (K) 63‐linked polyubiquitination of TRAF6 (E3 ubiquitin ligase activity); this results in the suppression of TLR4 inflammatory signaling in macrophages. Furthermore, we showed that the C‐terminal 123–131‐amino acid Rv2626c motif promotes macrophage recruitment, phagocytosis, M2 macrophage polarization, and subsequent bacterial clearance. We developed rRv2626c‐CA, a conjugated peptide containing the C‐terminal 123–131‐amino acid Rv2626c that targets macrophages, penetrates the cell membrane, and has demonstrated significant therapeutic effects in a mouse model of cecal ligation and puncture‐induced sepsis. This multifunctional rRv2626c‐CA has considerably improved potency, with an IC₅₀ that is 250‐fold (in vitro) or 1,000‐fold (in vivo) lower than that of rRv2626c‐WT. We provide evidence for new peptide‐based drugs with anti‐inflammatory and antibacterial properties for the treatment of sepsis.

Guanabenz modulates microglia and macrophages during demyelination

Multiple sclerosis (MS) is an autoimmune disease characterized by infiltration of peripheral immune cells into the central nervous system, demyelination, and neuronal damage. There is no cure for MS, but available disease-modifying therapies can lessen severity and delay progression. However, current therapies are suboptimal due to adverse effects. Here, we investigate how the FDA-approved antihypertensive drug, guanabenz, which has a favorable safety profile and was recently reported to enhance oligodendrocyte survival, exerts effects on immune cells, specifically microglia and macrophages. We first employed the experimental autoimmune encephalomyelitis (EAE) model and observed pronounced immunomodulation evident by a reduction in pro-inflammatory microglia and macrophages. When guanabenz was administered in the cuprizone model, in which demyelination is less dependent upon immune cells, we did not observe improvements in remyelination, oligodendrocyte numbers, and effects on microglial activation were less dramatic. Thus, guanabenz may be a promising therapeutic to minimize inflammation without exerting severe off-target effects.

Control of Bacterial Virulence through the Peptide Signature of the Habitat

To optimize fitness, pathogens selectively activate their virulence program upon host entry. Here, we report that the facultative intracellular bacterium Listeria monocytogenes exploits exogenous oligopeptides, a ubiquitous organic N source, to sense the environment and control the activity of its virulence transcriptional activator, PrfA. Using a genetic screen in adsorbent-treated (PrfA-inducing) medium, we found that PrfA is functionally regulated by the balance between activating and inhibitory nutritional peptides scavenged via the Opp transport system. Activating peptides provide essential cysteine precursor for the PrfA-inducing cofactor glutathione (GSH). Non-cysteine-containing peptides cause promiscuous PrfA inhibition. Biophysical and co-crystallization studies reveal that peptides inhibit PrfA through steric blockade of the GSH binding site, a regulation mechanism directly linking bacterial virulence and metabolism. L. monocytogenes mutant analysis in macrophages and our functional data support a model in which changes in the balance of antagonistic Opp-imported oligopeptides promote PrfA induction intracellularly and PrfA repression outside the host.

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Listeria PrfA virulence regulation is controlled by antagonistic nutritional peptides

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Opp-imported peptides regulate PrfA upstream of the activating cofactor GSH

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PrfA is activated by peptides that provide essential cysteine for GSH biosynthesis

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Blockade of PrfA’s GSH binding site by peptides inhibits virulence gene activation

Promotion of microglial phagocytosis by tuftsin stimulates remyelination in experimental autoimmune encephalomyelitis

Microglia were once thought to serve a pathogenic role in demyelinating diseases, particularly in multiple sclerosis (MS). However, it has recently been shown that in the experimental autoimmune encephalomyelitis (EAE) model of MS, microglia could serve a protective role by promoting remyelination via the efficient removal of apoptotic cells, the phagocytosis of debris and the support of myelinating oligodendrocytes. The aim of the present study was to determine if the effect of microglia could promote the recovery of EAE and attenuate symptoms in EAE. The severity of EAE was assessed by clinical scores, pathologic changes revealed by luxol fast blue staining and immunohistochemical techniques. The results suggested that microglia reduced clinical scores in mice, suppressed ongoing severe EAE and promoted remyelination and recovery in EAE mice. In addition, following induction with tuftsin, the M1/M2 cytokine balance was shifted, downregulating the proinflammatory M1 response and upregulating the anti-inflammatory M2 response. Generally, microglia can stimulate remyelination, which serves a protective role in different phases of EAE and may represent a potential therapeutic strategy for the treatment of MS.

Tuftsin-phosphorylcholine (TPC) equally effective to methylprednisolone in ameliorating lupus nephritis in a mice model

The role of helminth treatment in autoimmune diseases is growing constantly. Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease with challenging treatment options. Tuftsin-phosphorylcholine (TPC) is a novel helminth-based compound that modulates the host immune network. This study was conducted to evaluate the potential value of TPC in ameliorating lupus nephritis in a murine model and specifically to compare the efficacy of TPC to the existing first-line therapy for SLE: corticosteroids (methylprednisolone). Lupus-prone NZBxW/F₁ mice were treated with TPC (5 µg/mouse), methylprednisolone (MP; 5 mg/body weight) or phosphate-buffered saline (PBS) (control) three times per week once glomerulonephritis, defined as proteinuria of grade > 100 mg/dl, was established. Levels of anti-dsDNA autoantibodies were evaluated by enzyme-linked immunosorbent assay (ELISA), splenic cytokines were measured in vitro and the kidney microscopy was analysed following staining. TPC and MP treatments improved lupus nephritis significantly and prolonged survival in NZBxW/F₁ mice. TPC-treated mice showed a significantly decreased level of proteinuria (P < 0·001) and anti-dsDNA antibodies (P < 0·001) compared to PBS-treated mice. Moreover, TPC and MP inhibited the production of the proinflammatory cytokines interferon IFN-γ, interleukin IL-1β and IL-6 (P < 0·001) and enhanced expression of the anti-inflammatory cytokine IL-10 (P < 0·001). Finally, microscopy analysis of the kidneys demonstrated that TPC-treated mice maintained normal structure equally to MP-treated mice. These data indicate that the small molecule named TPC hinders lupus development in genetically lupus-prone mice equally to methylprednisolone in most of the cases. Hence, TCP may be employed as a therapeutic potential for lupus nephritis.

Tuftsin Combines With Remyelinating Therapy and Improves Outcomes in Models of CNS Demyelinating Disease

Though promoting remyelination in multiple sclerosis (MS) has emerged as a promising therapeutic strategy, it does not address inflammatory signals that continue to induce neuronal damage and inhibit effectiveness of repair mechanisms. Our lab has previously characterized the immunomodulatory tetrapeptide, tuftsin, which induces an anti-inflammatory shift in microglia and macrophages. This targeted anti-inflammatory agent improves physical deficits in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Here, we sought to determine whether tuftsin is also effective in combination with benztropine, an FDA-approved drug that stimulates remyelination, in both EAE and in the cuprizone model of demyelination. We show that combining these two agents to promote anti-inflammatory and remyelinating mechanisms alleviates symptoms in EAE and lessens pathological hallmarks in both MS models. Importantly, tuftsin is required to transform the inflammatory CNS environment normally present in EAE/MS into one of an anti-inflammatory nature, and benztropine is required in the cuprizone model to improve remyelination. Our data further support tuftsin's beneficial immunomodulatory activity in the context of EAE, and show that when studying remyelination in the absence of an autoimmune insult, tuftsin still activated microglia toward an anti-inflammatory fate, but benztropine was necessary for significant repair of the damaged myelin. Overall, tuftsin effectively combined with benztropine to significantly improve MS-like pathologies in both models.

Csf1R inhibition attenuates experimental autoimmune encephalomyelitis and promotes recovery

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by progressive neuronal demyelination and degeneration. Much of this damage can be attributed to microglia, the resident innate immune cells of the CNS, as well as monocyte-derived macrophages, which breach the blood-brain barrier in this inflammatory state. Upon activation, both microglia and macrophages release a variety of factors that greatly contribute to disease progression, and thus therapeutic approaches in MS focus on diminishing their activity. We use the CSF1R inhibitor PLX5622, administered in mouse chow, to ablate microglia and macrophages during the course of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Here, we show that ablation of these cells significantly improves animal mobility and weight gain in EAE. Further, we show that this treatment addresses the pathological hallmarks of MS, as it reduces demyelination and immune activation. White matter lesion areas in microglia/macrophage-depleted animals show substantial preservation of mature, myelinating oligodendrocytes in comparison to control animals. Taken together, these findings suggest that ablation of microglia/macrophages during the symptomatic phase of EAE reduces CNS inflammation and may also promote a more permissive environment for remyelination and recovery. This microglia and macrophage-targeted therapy could be a promising avenue for treatment of MS.

Tuftsin prevents the negative immunoregulation of neuropilin-1highCD4+CD25+Regulatory T cells and improves survival rate in septic mice

Our previous research showed that neuropilin (Nrp) -1highCD4+CD25+Regulatory T cells (Tregs) exhibited primary negative immunoregulation in sepsis induced immune dysfunction. Tuftsin is the typical ligand of Nrp-1. Herein, we investigated the potential therapeutic value and mechanisms of tuftsin in sepsis. Sepsis per se markedly decreased the serum concentration of tuftsin, administration of tuftsin improved the survival rate of septic mice with cecal ligation and puncture (CLP). In vitro study, tuftsin prevented the negative immunoregulation of Nrp-1highCD4+CD25+Tregs, including weakening the expression of forkhead/winged helix transcription factor (Foxp)- 3/cytotoxic T lymphocyte associated antigen (CTLA)-4, inhibiting the secretion of transforming growth factor (TGF)-β, and weakening the immunosuppressive function of Nrp-1highCD4+CD25+Tregs to conventional CD4+CD25-T cells. Tuftsin markedly inhibited the demethylation of Foxp3-Tregs specific demethylated region (TSDR) of Nrp-1highCD4+CD25+Tregs. Tuftsin could represent a new potential therapeutic agentia to improve the outcome of septic mice, and associate with preventing the negative immunoregulation of Tregs via Nrp-1.

Multifaceted Role of Neuropilins in the Immune System: Potential Targets for Immunotherapy

Neuropilins (NRPs) are non-tyrosine kinase cell surface glycoproteins expressed in all vertebrates and widely conserved across species. The two isoforms, such as neuropilin-1 (NRP1) and neuropilin-2 (NRP2), mainly act as coreceptors for class III Semaphorins and for members of the vascular endothelial growth factor family of molecules and are widely known for their role in a wide array of physiological processes, such as cardiovascular, neuronal development and patterning, angiogenesis, lymphangiogenesis, as well as various clinical disorders. Intriguingly, additional roles for NRPs occur with myeloid and lymphoid cells, in normal physiological as well as different pathological conditions, including cancer, immunological disorders, and bone diseases. However, little is known concerning the molecular pathways that govern these functions. In addition, NRP1 expression has been characterized in different immune cellular phenotypes including macrophages, dendritic cells, and T cell subsets, especially regulatory T cell populations. By contrast, the functions of NRP2 in immune cells are less well known. In this review, we briefly summarize the genomic organization, structure, and binding partners of the NRPs and extensively discuss the recent advances in their role and function in different immune cell subsets and their clinical implications.

The cholinergic anti-inflammatory pathway: An innovative treatment strategy for neurological diseases

Acetylcholine (ACh), as a classical neurotransmitter, regulates the neuronal network in response to internal and external stimuli. In recent decades, the biology of ACh has been endowed with unparalleled new insights, especially with respect to cholinergic anti-inflammatory properties in non-neuronal cells. In fact, a mechanism frequently referred to as the "cholinergic anti-inflammatory pathway" has been termed to describe interactions between the central nervous system (CNS) and the immune system via vagus nerve. As well documented, immune cells express choline acetyltransferase, a direct synthetase for ACh, and other corresponding cholinergic components. Alternatively, the ACh released from immune cells or cholinergic neurons modulates immune function in an autocrine/paracrine manner by acting on its receptors. Moreover, muscarinic or nicotinic ACh receptors on various immune cells and CNS glial cells administer the work of their respective agonists, causing functional and biochemical changes. In this review, we focus on the anti-inflammatory benefits of non-neuronal and neuronal ACh as a means of providing new insights into treating inflammation-related neurological diseases, as exemplified by those described herein.

The Diverse Roles of Microglia in the Neurodegenerative Aspects of Central Nervous System (CNS) Autoimmunity

Autoimmune diseases of the central nervous system (CNS) involve inflammatory components and result in neurodegenerative processes. Microglia, the resident macrophages of the CNS, are the first responders after insults to the CNS and comprise a major link between the inflammation and neurodegeneration. Here, we will focus on the roles of microglia in two autoimmune diseases: the prevalent condition of multiple sclerosis (MS) and the much rarer Rasmussen’s encephalitis (RE). Although there is an abundance of evidence that microglia actively contribute to neuronal damage in pathological states such as MS and RE, there is also evidence of important reparative functions. As current research supports a more complex and diverse array of functions and phenotypes that microglia can assume, it is an especially interesting time to examine what is known about both the damaging and restorative roles that microglia can play in the inflammatory CNS setting. We will also discuss the pharmacological approaches to modulating microglia towards a more neuroprotective state.

The diffuse reduction in spleen density: an indicator of severe acute pancreatitis?

We observed that acute pancreatitis (AP) was associated with diffuse reduction in spleen density (DROSD) in some patients. Furthermore, the condition of these patients was more serious, and the potential relationship between DROSD and structural and functional injury of the spleen remained unclear. Therefore, we performed a preliminary exploration of these factors. We analysed pertinent clinical data for AP patients with normal spleen density (control group) and for those with DROSD (reduction group) at the First Affiliated Hospital of Harbin Medical University (June 2013–June 2015). We measured the immunoglobulin M (IgM) B-cells of the AP patients and examined pancreatic and splenic tissues from AP rats with optical microscopy and TEM. The reduction group had a higher acute physiology and chronic health evaluation II (APACHE II) score, a longer length of stay (LOS) and lower serum calcium than the control group. The levels of triglycerides (TG) and total cholesterol (TC) did not differ significantly between the two groups. The percentage of IgM memory B-cells was significantly lower in the DROSD group than in the control group. TEM revealed that the spleen T-lymphocytes were normal in AP rats, but pyroptotic and necrotic spleen B-cells were observed in the severe AP rats. In AP, DROSD was an independent indicator of more severe conditions. Furthermore, spleen B-lymphocytes showed obvious damage at the cellular level, and the immunological function of the spleen was down-regulated when AP was associated with DROSD.

The farnesoid-X-receptor in myeloid cells controls CNS autoimmunity in an IL-10-dependent fashion

Innate immune responses by myeloid cells decisively contribute to perpetuation of central nervous system (CNS) autoimmunity and their pharmacologic modulation represents a promising strategy to prevent disease progression in Multiple Sclerosis (MS). Based on our observation that peripheral immune cells from relapsing-remitting and primary progressive MS patients exhibited strongly decreased levels of the bile acid receptor FXR (farnesoid-X-receptor, NR1H4), we evaluated its potential relevance as therapeutic target for control of established CNS autoimmunity. Pharmacological FXR activation promoted generation of anti-inflammatory macrophages characterized by arginase-1, increased IL-10 production, and suppression of T cell responses. In mice, FXR activation ameliorated CNS autoimmunity in an IL-10-dependent fashion and even suppressed advanced clinical disease upon therapeutic administration. In analogy to rodents, pharmacological FXR activation in human monocytes from healthy controls and MS patients induced an anti-inflammatory phenotype with suppressive properties including control of effector T cell proliferation. We therefore, propose an important role of FXR in control of T cell-mediated autoimmunity by promoting anti-inflammatory macrophage responses.

Novel therapeutic compound tuftsin-phosphorylcholine attenuates collagen-induced arthritis

Treatment with helminthes and helminthes ova improved the clinical symptoms of several autoimmune diseases in patients and in animal models. Phosphorylcholine (PC) proved to be the immunomodulatory molecule. We aimed to decipher the tolerogenic potential of tuftsin-PC (TPC), a novel helminth-based compound in collagen-induced arthritis (CIA) a mouse model of rheumatoid arthritis (RA). CIA DBA/1 mice were treated with TPC subcutaneously (5 µg/0.1 ml) or orally (250 µg/0.1 ml), starting prior to disease induction. The control groups were treated with PBS. Collagen antibodies were tested by enzyme-linked immunosorbent assay (ELISA), cytokine protein levels by ELISA kits and regulatory T (Treg ) and regulatory B (Breg ) cell phenotypes by fluorescence-activated cell sorter (FACS). TPC-treated mice had a significantly lower arthritis score of 1.5 in comparison with control mice 11.8 (P < 0.0001) in both subcutaneous and orally treated groups at day 31. Moreover, histology analysis demonstrated highly inflamed joints in control mice, whereas TPC-treated mice maintained normal joint structure. Furthermore, TPC decreased the titres of circulating collagen II antibodies in mice sera (P < 0.0001), enhanced expression of IL-10 (P < 0.0001) and inhibited production of tumour necrosis factor (TNF)-α, interleukin (IL)-17 and IL-1β (P < 0.0001). TPC significantly expanded the CD4(+) CD25(+) forkhead box protein 3 (FoxP3(+) ) Treg cells and CD19(+) IL-10(+) CD5(high) CD1d(high) T cell immunoglobulin mucin-1 (TIM-1(+) ) Breg cell phenotypes (P < 0.0001) in treated mice. Our data indicate that treatment with TPC attenuates CIA in mice demonstrated by low arthritic score and normal joints histology. TPC treatment reduced proinflammatory cytokines and increased anti-inflammatory cytokine expression, as well as expansion of Treg and Breg cells. Our results may lead to a new approach for a natural therapy for early rheumatoid arthritis onset.

Tuftsin-driven experimental autoimmune encephalomyelitis recovery requires neuropilin-1

Experimental autoimmune encephalomyelitis (EAE) is an animal model of demyelinating autoimmune disease, such as multiple sclerosis (MS), which is characterized by central nervous system white matter lesions, microglial activation, and peripheral T-cell infiltration secondary to blood-brain barrier disruption. We have previously shown that treatment with tuftsin, a tetrapeptide generated from IgG proteolysis, dramatically improves disease symptoms in EAE. Here, we report that microglial expression of Neuropilin-1 (Nrp1) is required for tuftsin-driven amelioration of EAE symptoms. Nrp1 ablation in microglia blocks microglial signaling and polarization to the anti-inflammatory M2 phenotype, and ablation in either the microglia or immunosuppressive regulatory T cells (Tregs) reduces extended functional contacts between them and Treg activation, implicating a role for microglia in the activation process, and more generally, how immune surveillance is conducted in the CNS. Taken together, our findings delineate the mechanistic action of tuftsin as a candidate therapeutic against immune-mediated demyelinating lesions.

Tuftsin-derived T-peptide prevents cellular immunosuppression and improves survival rate in septic mice

The primary mechanisms of sepsis induced cellular immunesuppression involve immune dysfunction of T lymphocytes and negative immunoregulation of regulatory T cells (Tregs). It has been found that tuftsin is an immune modulating peptide derived from IgG in spleen. T-peptide is one of tuftsin analogs. Herein, we examined the effect of T-peptide on cell-mediated immunity in the presence of lipopolysaccharide (LPS) and the survival rate in septic mice. T-peptide regulated the proliferative ability of CD4⁺CD25⁻ T cells in dual responses. Meanwhile, 10 and 100 μg/ml T-peptides were able to enhance the apoptotic rate of CD4⁺CD25⁻ T cells compared with 1 μg/ml T-peptide, but markedly lowered interleukin (IL)-2 levels. When CD4⁺CD25⁺ Tregs were treated with T-peptide for 24 hours, and co-cultured with normal CD4⁺CD25⁻ T cells, the suppressive ability of CD4⁺CD25⁺ Tregs on CD4⁺CD25⁻ T cells was significantly lowered, along with decreased expression in forkhead/winged helix transcription factor p-3 (Foxp-3) as well as cytotoxic T lymphocyte-associated antigen (CTLA)-4, and secretion of transforming growth factor (TGF)-β. Moreover, T-peptide has the ability to improve outcome of septic mice in a dose- and time- dependent manner, and associated with improvement in the microenvironment of cellular immunosuppression in septic mice.

Pharmacokinetics and bioavailability of tuftsin-derived T peptide, a promising antitumor agent, in beagles

Tuftsin, a natural phagocytosis-stimulating tetrapeptide, had aroused much interest in tumor immunotherapy, but the poor pharmacokinetics hampered its clinical developments, for that it was extremely susceptible to degradation by enzymolysis in vivo. T Peptide (TP) was a newly designed tuftsin derivative aimed to enhance stability and was proved to have significant antitumor activity. In this study, the pharmacokinetics and bioavailability of TP was first clarified in beagles with subcutaneous administration, by using a simple and robust competitive ELISA method. Dose-dependency and non-linear dynamics of TP after single-dose (2, 6 and 18 mg kg(-1), respectively) were found, and the half-time of TP was proved to reach 1.3-2.8 h. Multiple dosing of 6 mg kg(-1) once a day for 7 days resulted in a slight accumulation (accumulation index was 1.92 ± 0.43), indicating that the dosing interval in the following clinical trial needs to be extended. The absolute bioavailability of TP was 31.1 ± 6.2% after subcutaneous administration. These results first demonstrated the pharmacokinetics and bioavailability data of TP in vivo, which illustrated the potential druggability of TP and provided useful information for the dosage regimen design in the following clinical trials, as well as a simple and feasible analytical method for clinical sample analysis.

Nicotine modulates neurogenesis in the central canal during experimental autoimmune encephalomyelitis

Nicotine has been shown to attenuate experimental autoimmune encephalomyelitis (EAE) through inhibiting inflammation in microglial populations during the disease course. In this study, we investigated whether nicotine modified the regenerative process in EAE by examining nestin-expressing neural stem cells (NSCs) in the spinal cord, which is the primary area of demyelination and inflammation in EAE. Our results show that the endogenous neurogenic responses in the spinal cord after EAE are limited and delayed: while nestin expression is increased, the proliferation of ependymal cells is inhibited compared to healthy animals. Nicotine application significantly reduced nestin expression and partially allowed for the proliferation of ependymal cells. We found that reduction of ependymal cell proliferation correlated with inflammation in the same area, which was relieved by the administration of nicotine. Further, increased numbers of oligodendrocytes (OLs) were observed after nicotine treatment. These findings give a new insight into the mechanism of how nicotine functions to attenuate EAE.

Modified laparoscopic splenectomy and azygoportal disconnection combined with cell salvage is feasible and might reduce the need for blood transfusion

AIM: To investigate perioperative outcomes in patients undergoing modified laparoscopic splenectomy and azygoportal disconnection (MLSD) with intraoperative autologous cell salvage.

METHODS: We retrospectively evaluated outcomes in 79 patients admitted to the Clinical Medical College of Yangzhou University with cirrhosis, portal hypertensive bleeding and secondary hypersplenism who underwent MLSD without (n = 46) or with intraoperative cell salvage and autologous blood transfusion, including splenic blood and operative hemorrhage (n = 33), between February 2012 and January 2014. Their intraoperative and postoperative variables were compared. These variables mainly included: operation time; estimated intraoperative blood loss; volume of allogeneic blood transfused; visual analog scale for pain on the first postoperative day; time to first oral intake; initial passage of flatus and off-bed activity; perioperative hemoglobin (Hb) concentration; and red blood cell concentration.

RESULTS: There were no significant differences between the groups in terms of duration of surgery, estimated intraoperative blood loss and overall perioperative complication rate. In those receiving salvaged autologous blood, Hb concentration increased by an average of 11.2 ± 4.8 g/L (P < 0.05) from preoperative levels by the first postoperative day, but it had fallen by 9.8 ± 6.45 g/L (P < 0.05) in the group in which cell salvage was not used. Preoperative Hb was similar in the two groups (P > 0.05), but Hb on the first postoperative day was significantly higher in the autologous blood transfusion group (118.5 ± 15.8 g/L vs 102.7 ± 15.6 g/L, P < 0.05). The autologous blood transfusion group experienced significantly fewer postoperative days of temperature > 38.0 °C (P < 0.05).

CONCLUSION: Intraoperative cell salvage during MLSD is feasible and safe and may become the gold standard for liver cirrhosis with portal hypertensive bleeding and hypersplenism.

Tuftsin-based, EGFR-targeting fusion protein and its enediyne-energized analog show high antitumor efficacy associated with CD47 down-regulation

Tuftsin (TF) is an immunomodulator tetrapeptide (Thr-Lys-Pro-Arg) that binds to the receptor neuropilin-1 (Nrp1) on the surface of cells. Many reports have described anti-tumor activity of tuftsin to relate with nonspecific activation of the host immune system. Lidamycin (LDM) that displays extremely potent cytotoxicity to cancer cells is composed of an apoprotein (LDP) and an enediyne chromophore (AE). In addition, Ec is an EGFR-targeting oligopeptide. In the present study, LDP was used as protein scaffold and the specific carrier for the highly potent AE. Genetically engineered fusion proteins LDP-TF and Ec-LDP-TF were prepared; then, the enediyne-energized fusion protein Ec-LDM-TF was generated by integration of AE into Ec-LDP-TF. The tuftsin-based fusion proteins LDP-TF and Ec-LDP-TF significantly enhanced the phagocytotic activity of macrophages as compared with LDP (P < 0.05). Ec-LDP-TF effectively bound to tumor cells and macrophages; furthermore, it markedly suppressed the growth of human epidermoid carcinoma A431 xenograft in athymic mice by 84.2 % (P < 0.05) with up-regulated expression of TNF-α and IFN-γ. Ec-LDM-TF further augmented the therapeutic efficacy, inhibiting the growth of A431 xenograft by 90.9 % (P < 0.05); notably, the Ec-LDM-TF caused marked down-regulation of CD47 in A431 cells. Moreover, the best therapeutic effect was recorded in the group of animals treated with the combination of Ec-LDP-TF with Ec-LDM-TF. The results suggest that tuftsin-based, enediyne-energized, and EGFR-targeting fusion proteins exert highly antitumor efficacy with CD47 modulation. Tuftsin-based fusion proteins are potentially useful for treatment of EGFR- and CD47-overexpressing cancers.

The experimental autoimmune encephalomyelitis disease course is modulated by nicotine and other cigarette smoke components

Epidemiological studies have reported that cigarette smoking increases the risk of developing multiple sclerosis (MS) and accelerates its progression. However, the molecular mechanisms underlying these effects remain unsettled. We have investigated here the effects of the nicotine and the non-nicotine components in cigarette smoke on MS using the experimental autoimmune encephalomyelitis (EAE) model, and have explored their underlying mechanism of action. Our results show that nicotine ameliorates the severity of EAE, as shown by reduced demyelination, increased body weight, and attenuated microglial activation. Nicotine administration after the development of EAE symptoms prevented further disease exacerbation, suggesting that it might be useful as an EAE/MS therapeutic. In contrast, the remaining components of cigarette smoke, delivered as cigarette smoke condensate (CSC), accelerated and increased adverse clinical symptoms during the early stages of EAE, and we identify a particular cigarette smoke compound, acrolein, as one of the potential mediators. We also show that the mechanisms underlying the opposing effects of nicotine and CSC on EAE are likely due to distinct effects on microglial viability, activation, and function.

The impact of neuroimmune changes on development of amyloid pathology; relevance to Alzheimer's disease

Neuroinflammatory changes are a characteristic of several, if not all, neurodegenerative diseases including Alzheimer's disease and are typified by increased microglial activation. Microglia express several receptors making them highly reactive and plastic cells, and, at least in vitro, they adopt different phenotypes in a manner analogous to their peripheral counterparts, macrophages. Microglia also express numerous cell surface proteins enabling them to interact with cells and the evidence indicates that maintenance of microglia in a quiescent state relies, at least to some extent, on an interaction with neurons by means of specific ligand-receptor pairs, for example CD200-CD200R. It is clear that microglia also interact with T cells and recent evidence indicates that co-incubation of microglia with T helper type 1 cells markedly increases their activation. Under normal conditions, small numbers of activated T cells gain entry to the brain and are involved in immune surveillance but infiltration of significant numbers of T cells occurs in disease and following injury. The consequences of T cell infiltration appear to depend on the conditions, with descriptions of both neurodestructive and neuroprotective effects in animal models of different diseases. This review will discuss the modulatory effect of T cells on microglia and the impact of infiltration of T cells into the brain with a focus on Alzheimer's disease, and will propose that infiltration of interferon-γ-producing cells may be an important factor in triggering inflammation that is pathogenic and destructive.

Macrophages: a double-edged sword in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a debilitating neurological disorder of the central nervous system (CNS), characterized by activation and infiltration of leukocytes and dendritic cells into the CNS. In the initial phase of MS and its animal model, experimental autoimmune encephalomyelitis (EAE), peripheral macrophages infiltrate into the CNS, where, together with residential microglia, they participate in the induction and development of disease. During the early phase, microglia/macrophages are immediately activated to become classically activated macrophages (M1 cells), release pro-inflammatory cytokines and damage CNS tissue. During the later phase, microglia/macrophages in the inflamed CNS are less activated, present as alternatively activated macrophage phenotype (M2 cells), releasing anti-inflammatory cytokines, accompanied by inflammation resolution and tissue repair. The balance between activation and polarization of M1 cells and M2 cells in the CNS is important for disease progression. Pro-inflammatory IFN-γ and IL-12 drive M1 cell polarization, while IL-4 and IL-13 drive M2 cell polarization. Given that polarized macrophages are reversible in a well-defined cytokine environment, macrophage phenotypes in the CNS can be modulated by molecular intervention. This review summarizes the detrimental and beneficial roles of microglia and macrophages in the CNS, with an emphasis on the role of M2 cells in EAE and MS patients.

Microglia: an active player in the regulation of synaptic activity

Synaptic plasticity is critical for elaboration and adaptation in the developing and developed brain. It is well established that astrocytes play an important role in the maintenance of what has been dubbed “the tripartite synapse”. Increasing evidence shows that a fourth cell type, microglia, is critical to this maintenance as well. Microglia are the resident macrophages of the central nervous system (CNS). Because of their well-characterized inflammatory functions, research has primarily focused on their innate immune properties. The role of microglia in the maintenance of synapses in development and in homeostasis is not as well defined. A number of significant findings have shed light on the critical role of microglia at the synapse. It is becoming increasingly clear that microglia play a seminal role in proper synaptic development and elimination.

Tuftsin signals through its receptor neuropilin-1 via the transforming growth factor beta pathway

Tuftsin (Thr-Lys-Pro-Arg) is a natural immunomodulating peptide found to stimulate phagocytosis in macrophages/microglia. Tuftsin binds to the receptor neuropilin-1 (Nrp1) on the surface of cells. Nrp1 is a single-pass transmembrane protein, but its intracellular C-terminal domain is too small to signal independently. Instead, it associates with a variety of coreceptors. Despite its long history, the pathway through which tuftsin signals has not been described. To investigate this question, we employed various inhibitors to Nrp1's coreceptors to determine which route is responsible for tuftsin signaling. We use the inhibitor EG00229, which prevents tuftsin binding to Nrp1 on the surface of microglia and reverses the anti-inflammatory M2 shift induced by tuftsin. Furthermore, we demonstrate that blockade of transforming growth factor beta (TGFβ) signaling via TβR1 disrupts the M2 shift similar to EG00229. We report that tuftsin promotes Smad3 phosphorylation and reduces Akt phosphorylation. Taken together, our data show that tuftsin signals through Nrp1 and the canonical TGFβ signaling pathway. Despite the 40-year history of the tetrapeptide tuftsin (TKPR), a macrophage and microglial activator, its mechanism of action has not been defined. Here, we report that the tuftsin-mediated anti-inflammatory M2 shift in microglia is caused specifically by tuftsin binding to the receptor neuropilin-1 (Nrp1) and signaling through TGFβ receptor-1, a coreceptor of Nrp1. We further show that tuftsin signals via the canonical TGFβ pathway and promotes TGFβ release from target cells.

Role of microglia in CNS autoimmunity

Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system (CNS) in the Western world. The disease is characterized histologically by the infiltration of encephalitogenic T_H1/T_H17-polarized CD4⁺ T cells, B cells, and a plethora of myeloid cells, resulting in severe demyelination ultimately leading to a degeneration of neuronal structures. These pathological processes are substantially modulated by microglia, the resident immune competent cells of the CNS. In this overview, we summarize the current knowledge regarding the highly diverse and complex function of microglia during CNS autoimmunity in either promoting tissue injury or tissue repair. Hence, understanding microglia involvement in MS offers new exciting paths for therapeutic intervention.