Pivotal Advance: Vasoactive intestinal peptide inhibits up-regulation of human monocyte TLR2 and TLR4 by LPS and differentiation of monocytes to macrophages

Prenatal lipopolysaccharide exposure induces anxiety-like behaviour in male mouse offspring and aberrant glial differentiation of embryonic neural stem cells

BACKGROUND

Prenatal infection has been implicated in the development of neuropsychiatric disorders in children. We hypothesised that exposure to lipopolysaccharide during prenatal development could induce anxiety-like behaviour and sensorineural hearing loss in offspring, as well as disrupt neural differentiation during embryonic neural development.

METHODS

We simulated prenatal infection in FVB mice and mouse embryonic stem cell (ESC) lines, specifically 46C and E14Tg2a, through lipopolysaccharide treatment. Gene expression profiling analyses and behavioural tests were utilized to study the effects of lipopolysaccharide on the offspring and alterations in toll-like receptor (TLR) 2-positive and TLR4-positive cells during neural differentiation in the ESCs.

RESULTS

Exposure to lipopolysaccharide (25 µg/kg) on gestation day 9 resulted in anxiety-like behaviour specifically in male offspring, while no effects were detected in female offspring. We also found significant increases in the expression of GFAP and CNPase, as well as higher numbers of GFAP + astrocytes and O4+ oligodendrocytes in the prefrontal cortex of male offspring. Furthermore, increased scores for genes related to oligodendrocyte and lipid metabolism, particularly ApoE, were observed in the prefrontal cortex regions. Upon exposure to lipopolysaccharide during the ESC-to-neural stem cell (NSC) transition, Tuj1, Map2, Gfap, O4, and Oligo2 mRNA levels increased in the differentiated neural cells on day 14. In vitro experiments demonstrated that lipopolysaccharide exposure induced inflammatory responses, as evidenced by increased expression of IL1b and ApoB mRNA.

CONCLUSIONS

Our findings suggest that prenatal infection at different stages of neural differentiation may result in distinct disturbances in neural differentiation during ESC-NSC transitions. Furthermore, early prenatal challenges with lipopolysaccharide selectively induce anxiety-like behaviour in male offspring. This behaviour may be attributed to the abnormal differentiation of astrocytes and oligodendrocytes in the brain, potentially mediated by ApoB/E signalling pathways in response to inflammatory stimuli.

Neural Regulations in Tooth Development and Tooth-Periodontium Complex Homeostasis: A Literature Review

The tooth-periodontium complex and its nerves have active reciprocal regulation during development and homeostasis. These effects are predominantly mediated by a range of molecules secreted from either the nervous system or the tooth-periodontium complex. Different strategies mimicking tooth development or physiological reparation have been applied to tooth regeneration studies, where the application of these nerve- or tooth-derived molecules has been proven effective. However, to date, basic studies in this field leave many vacancies to be filled. This literature review summarizes the recent advances in the basic studies on neural responses and regulation during tooth-periodontium development and homeostasis and points out some research gaps to instruct future studies. Deepening our understanding of the underlying mechanisms of tooth development and diseases will provide more clues for tooth regeneration.

Macrophage orchestration of epithelial and stromal cell homeostasis in the intestine

The intestinal tract is a complex ecosystem where numerous cell types of epithelial, immune, neuronal, and endothelial origin coexist in an intertwined, highly organized manner. The functional equilibrium of the intestine relies heavily on the proper crosstalk and cooperation among each cell population. Furthermore, macrophages are versatile, innate immune cells that participate widely in the modulation of inflammation and tissue remodeling. Emerging evidence suggest that macrophages are central in orchestrating tissue homeostasis. Herein, we describe how macrophages interact with epithelial cells, neurons, and other types of mesenchymal cells under the context of intestinal inflammation, followed by the therapeutic implications of cellular crosstalk pertaining to the treatment of inflammatory bowel disease.

Two transcription factors PU.1a and PU.1b have different functions in the immune system of teleost ayu

Transcription factor PU.1 is a regulator of macrophage function, however, the specific function of PU.1 in teleost monocytes/macrophages (MO/MФ) remains unknown. We determined the cDNA sequence of two PU.1 genes from ayu (Plecoglossus altivelis; PaPU.1a and PaPU.1b). Sequence comparisons showed that PaPU.1 were most closely related to the PU.1 of rainbow smelt (Osmerus mordax). The PU.1 transcripts were mainly expressed in the spleen, and their expression was altered in various tissues upon infection with Vibrio anguillarum. PaPU.1a and PaPU.1b proteins were upregulated in MO/MФ, after infection. RNA interference was employed to knockdown PaPU.1a and PaPU.1b to investigate their function in MO/MФ. The expression of inflammatory cytokines was regulated by PaPU.1a, but not PaPU.1b, in ayu MO/MФ upon V. anguillarum infection. Both PaPU.1a and PaPU.1b knockdown lowered the phagocytic activity of MO/MФ. Furthermore, PaPU.1b knockdown attenuated MO/MФ bacterial killing capability. Our results indicate that two PaPU.1 genes differentially modulate the immune response in ayu MO/MФ against bacterial infection.

Toll-like receptor 4 is a therapeutic target for prevention and treatment of liver failure

BACKGROUND & AIMS

Toll-like receptor 4 (TLR4) plays an essential role in mediating organ injury in acute liver failure (ALF) and acute-on-chronic liver failure (ACLF). Herein, we assess whether inhibiting TLR4 signaling can ameliorate liver failure and serve as a potential treatment.

METHODS

Circulating TLR4 ligands and hepatic TLR4 expression were measured in plasma samples and liver biopsies from patients with cirrhosis. TAK-242 (TLR4 inhibitor) was tested in vivo (10 mg/kg intraperitoneally) in rodent models of ACLF (bile duct ligation + lipopolysaccharide [LPS]; carbon tetrachloride + LPS) and ALF (galactosamine + LPS) and in vitro on immortalized human monocytes (THP-1) and hepatocytes (HHL5). The in vivo therapeutic effect was assessed by coma-free survival, organ injury and cytokine release and in vitro by measuring IL-6, IL-1β or cell injury (TUNEL), respectively.

RESULTS

In patients with cirrhosis, hepatic TLR4 expression was upregulated and circulating TLR4 ligands were increased (p <0.001). ACLF in rodents was associated with a switch from apoptotic cell death in ALF to non-apoptotic forms of cell death. TAK-242 reduced LPS-induced cytokine secretion and cell death (p = 0.002) in hepatocytes and monocytes in vitro. In rodent models of ACLF, TAK-242 administration improved coma-free survival, reduced the degree of hepatocyte cell death in the liver (p <0.001) and kidneys (p = 0.048) and reduced circulating cytokine levels (IL-1β, p <0.001). In a rodent model of ALF, TAK-242 prevented organ injury (p <0.001) and systemic inflammation (IL-1β, p <0.001).

CONCLUSION

This study shows that TLR4 signaling is a key factor in the development of both ACLF and ALF; its inhibition reduces the severity of organ injury and improves outcome. TAK-242 may be of therapeutic relevance in patients with liver failure.

LAY SUMMARY

Toll-like receptor 4 (or TLR4) mediates endotoxin-induced tissue injury in liver failure and cirrhosis. This receptor sensitizes cells to endotoxins, which are produced by gram-negative bacteria. Thus, inhibiting TLR4 signaling with an inhibitor (TAK-242) ameliorates organ injury and systemic inflammation in rodent models of acute and acute-on-chronic liver failure.

A Clinical Approach for the Use of VIP Axis in Inflammatory and Autoimmune Diseases

The neuroendocrine and immune systems are coordinated to maintain the homeostasis of the organism, generating bidirectional communication through shared mediators and receptors. Vasoactive intestinal peptide (VIP) is the paradigm of an endogenous neuropeptide produced by neurons and endocrine and immune cells, involved in the control of both innate and adaptive immune responses. Exogenous administration of VIP exerts therapeutic effects in models of autoimmune/inflammatory diseases mediated by G-protein-coupled receptors (VPAC1 and VPAC2). Currently, there are no curative therapies for inflammatory and autoimmune diseases, and patients present complex diagnostic, therapeutic, and prognostic problems in daily clinical practice due to their heterogeneous nature. This review focuses on the biology of VIP and VIP receptor signaling, as well as its protective effects as an immunomodulatory factor. Recent progress in improving the stability, selectivity, and effectiveness of VIP/receptors analogues and new routes of administration are highlighted, as well as important advances in their use as biomarkers, contributing to their potential application in precision medicine. On the 50th anniversary of VIP's discovery, this review presents a spectrum of potential clinical benefits applied to inflammatory and autoimmune diseases.

Protective effects of dioscin against systemic inflammatory response syndromevia adjusting TLR2/MyD88/NF‑κb signal pathway

Development of active compounds to control inflammation against systemic inflammatory response syndrome (SIRS) is critical important. Dioscin shows anti-inflammatory effects in our previous works. However, the action of the compound on SIRS still remained unknown. In the present paper, zymosan induced generalized inflammation (ZIGI) models in mice and rats, and PMA-differentiated THP‑1 cells stimulated by lipopolysaccharide (LPS) and Pam3-Cys-Ser-Lys4 (Pam3CSK4) were used. The results showed that dioscin significantly inhibited the proliferation of THP‑1 cells stimulated by LPS and Pam3CSK4, obviously reduced the soakage of inflammatory cells and necrosis in liver, kidney and intestine of rats and mice, and reduced peritoneal ascites fluid compared with ZIGI model groups. In addition, dioscin significantly declined the levels of alanine transaminase (ALT), aspartate transaminase (AST), creatinine (Cr), blood urea nitrogen (BUN), malondialdehyde (MDA) and myeloperoxidase (MPO), increased the levels of superoxide dismutase (SOD) in rats and mice. The migration of macrophages in tissues was also suppressed by dioscin. Mechanism investigation showed that dioscin significantly inhibited the expression levels of TLR2, MyD88, NF‑κb, HMGB‑1, increased the expression levels of IKBα, and decreased the mRNA levels of interleukin‑1 beta (IL‑1β), interleukin‑6 (IL‑6) and tumor necrosis factor‑alpha (TNF‑α) in liver, kidney, intestine tissues of rats and mice, and in PMA-differentiated THP‑1 cells, which were further confirmed by TLR2 siRNA silencing in vitro. In conclusion, our data confirmed that dioscin exhibited protective effects against SIRS via adjusting TLR2/MyD88 signal pathway, which should be developed as one potent candidate to treat SIRS in the future.

The Enteric Network: Interactions between the Immune and Nervous Systems of the Gut

Interactions between the nervous and immune systems enable the gut to respond to the variety of dietary products that it absorbs, the broad spectrum of pathogens that it encounters, and the diverse microbiome that it harbors. The enteric nervous system (ENS) senses and reacts to the dynamic ecosystem of the gastrointestinal (GI) tract by translating chemical cues from the environment into neuronal impulses that propagate throughout the gut and into other organs in the body, including the central nervous system (CNS). This review will describe the current understanding of the anatomy and physiology of the GI tract by focusing on the ENS and the mucosal immune system. We highlight emerging literature that the ENS is essential for important aspects of microbe-induced immune responses in the gut. Although most basic and applied research in neuroscience has focused on the brain, the proximity of the ENS to the immune system and its interface with the external environment suggest that novel paradigms for nervous system function await discovery.

VIP Inhibits P. gingivalis LPS-induced IL-18 and IL-18BPa in Monocytes

IL-18 is a pro-inflammatory cytokine that is important in the regulation of T-cells and is elevated in inflammatory disorders such as periodontal disease. Vasoactive intestinal peptide (VIP) modulates immune responses to the periodontal pathogen Porphyromonas gingivalis ( Pg). Our objective was to investigate the effect of Pg LPS on IL-18 and its natural inhibitor, IL-18 binding protein (IL-18BPa), in human monocytes, and the effect of VIP on this system. We demonstrated that Pg LPS induced both IL-18 and IL-18BPa secretion in cultures of the human monocytic cell line THP-1, as measured by specific ELISA. The addition of antibodies to IL-18BPa to the stimulated THP-1 cultures resulted in increased levels of free IL-18, indicating a specific interaction between IL18 and IL-18BPa in this system. VIP (10−8M) inhibited both IL-18 and IL-18Bpa secretion by stimulated monocytes. We conclude that IL-18 and IL-18BPa secretion by monocytes is part of the immune response to Pg, and that VIP can inhibit this process.

VIP impairs acquisition of the macrophage proinflammatory polarization profile

This study tested the hypothesis that vasoactive intestinal peptide (VIP) is able to modify the macrophage inflammatory profile, thus supporting its therapeutic role in autoimmune diseases. Macrophages are innate immune cells that display a variety of functions and inflammatory profiles in response to the environment that critically controls their polarization. Deregulation between the pro- and anti-inflammatory phenotypes has been involved in different pathologies. Rheumatoid arthritis (RA) is an autoimmune disease, in which macrophages are considered central effectors of synovial inflammation, displaying a proinflammatory profile. VIP is a pleiotropic neuropeptide with proven anti-inflammatory actions. As modulation of the macrophage phenotype has been implicated in the resolution of inflammatory diseases, we evaluated whether VIP is able to modulate human macrophage polarization. In vitro-polarized macrophages by GM-CSF (GM-MØ), with a proinflammatory profile, expressed higher levels of VIP receptors, vasoactive intestinal polypeptide receptors 1 and 2 (VPAC1 and VPAC2, respectively), than macrophages polarized by M-CSF (M-MØ) with anti-inflammatory activities. RA synovial macrophages, according to their GM-CSF-like polarization state, expressed both VPAC1 and VPAC2. In vitro-generated GM-MØ exposed to VIP exhibited an up-regulation of M-MØ gene marker expression, whereas their proinflammatory cytokine profile was reduced in favor of an anti-inflammatory function. Likewise, in GM-MØ, generated in the presence of VIP, VIP somehow changes the macrophages physiology profile to a less-damaging phenotype. Therefore, these results add new value to VIP as an immunomodulatory agent on inflammatory diseases.

PU.1 is involved in the immune response to Aspergillus fumigatus through upregulating Dectin-1 expression

Background

Invasive aspergillosis is a life-threatening disease, and its incidence has increased in the recent past. Dectin-1 recognizes β-glucans and mediates innate immune responses to Aspergillus fumigatus. Transcription factor PU.1 has been the focus of recent research due to its role in inflammation and infection. However, its role in Dectin-1 regulation during A. fumigatus infection remains to be elucidated.

Methods

THP-1 cells were stimulated with A. fumigatus conidia. We then used real-time RT-PCR, Western blot, and immunofluorescence assays to analyze the mRNA and protein levels and cellular distribution, respectively, of Dectin-1 and PU.1 in stimulated THP-1 cells. Additionally, we used the luciferase reporter assays, chromatin immunoprecipitation (ChIP) assays, electrophoretic mobility shift assays (EMSA), and RNA interference experiments to investigate the role of PU.1 in Dectin-1 regulation.

Results

Our results revealed that Dectin-1 mRNA and protein levels as well as the PU.1 protein level were increased in THP-1 cells stimulated with A. fumigatus conidia, while the mRNA expression level did not significantly change between the stimulated and control groups. We also observed that PU.1 translocated into the nucleus in stimulated THP-1 cells. The results of the luciferase reporter assay showed that PU.1 promoted human Dectin-1 (hDectin-1) gene activity. ChIP and EMSA indicated that PU.1 could bind with hDectin-1 gene promoter at three potential transcription factor-binding sites (TFBSs). In addition, knockdown of PU.1 significantly decreased Dectin-1 expression.

Conclusions

This study demonstrated the novel role of PU.1 in the immune response to A. fumigatus through upregulation of Dectin-1 expression and its translocation to the nucleus in A. fumigatus-stimulated THP-1 cells.

The Neuromodulation of the Intestinal Immune System and Its Relevance in Inflammatory Bowel Disease

One of the main tasks of the immune system is to discriminate and appropriately react to “danger” or “non-danger” signals. This is crucial in the gastrointestinal tract, where the immune system is confronted with a myriad of food antigens and symbiotic microflora that are in constant contact with the mucosa, in addition to any potential pathogens. This large number of antigens and commensal microflora, which are essential for providing vital nutrients, must be tolerated by the intestinal immune system to prevent aberrant inflammation. Hence, the balance between immune activation versus tolerance should be tightly regulated to maintain intestinal homeostasis and to prevent immune activation indiscriminately against all luminal antigens. Loss of this delicate equilibrium can lead to chronic activation of the intestinal immune response resulting in intestinal disorders, such as inflammatory bowel diseases (IBD). In order to maintain homeostasis, the immune system has evolved diverse regulatory strategies including additional non-immunological actors able to control the immune response. Accumulating evidence strongly indicates a bidirectional link between the two systems in which the brain modulates the immune response via the detection of circulating cytokines and via direct afferent input from sensory fibers and from enteric neurons. In the current review, we will highlight the most recent findings regarding the cross-talk between the nervous system and the mucosal immune system and will discuss the potential use of these neuronal circuits and neuromediators as novel therapeutic tools to reestablish immune tolerance and treat intestinal chronic inflammation.

Vasoactive intestinal peptide (VIP) differentially affects inflammatory immune responses in human monocytes infected with viable Salmonella or stimulated with LPS

We compared the effect of VIP on human blood monocytes infected with Salmonella typhimurium 4/74 or stimulated with LPS. VIP (10(-7)M) increased monocyte viability by 24% and 9% when cultured for 24h with 4/74 or Salmonella LPS (100ng/ml), respectively. Significantly increased (P<0.05) numbers of 4/74 were also recovered from monocytes co-cultured with VIP after 6h post-infection (pi) and this remained high after 24h pi. Both 4/74 and LPS increased (P<0.05) the concentration of TNF-α, IL-1β and IL-6 measured in monocyte supernatants. However, LPS induced this effect more rapidly while, with the exception of IL-6, 4/74 induced higher concentrations (P<0.05). VIP significantly decreased (P<0.05) TNF-α and IL-1β production by 4/74-infected monocytes after 6 pi, but only after 24h in LPS-cultured monocytes. This trend was reversed for IL-6 production. However, TNF-α and IL-1β production by 4/74-infected monocytes, cultured with VIP, still remained higher (P<0.05) than concentrations measured in supernatants cultured only with LPS. VIP also increased (P<0.05) production of anti-inflammatory IL-10 in both 4/74 and LPS cultures after 24h. We also show a differential effect of VIP on the expression of TNFα and IL-6 receptors, since VIP was only able to decreased expression in LPS-stimulated monocytes but not in 4/74-infected monocytes. In conclusion, we show a differential effect of VIP on human monocytes infected with virulent Salmonella or stimulated with LPS. Our study suggests that the use of VIP in bacteraemia and/or sepsis may be limited to an adjunctive therapy to antibiotic treatment.

Microglia-Induced Maladaptive Plasticity Can Be Modulated by Neuropeptides In Vivo

Microglia-induced maladaptive plasticity is being recognized as a major cause of deleterious self-sustaining pathological processes that occur in neurodegenerative and neuroinflammatory diseases. Microglia, the primary homeostatic guardian of the central nervous system, exert critical functions both during development, in neural circuit reshaping, and during adult life, in the brain physiological and pathological surveillance. This delicate critical role can be disrupted by neural, but also peripheral, noxious stimuli that can prime microglia to become overreactive to a second noxious stimulus or worsen underlying pathological processes. Among regulators of microglia, neuropeptides can play a major role. Their receptors are widely expressed in microglial cells and neuropeptide challenge can potently influence microglial activity in vitro. More relevantly, this regulator activity has been assessed also in vivo, in experimental models of brain diseases. Neuropeptide action in the central nervous system has been associated with beneficial effects in neurodegenerative and neuroinflammatory pathological experimental models. This review describes some of the mechanisms of the microglia maladaptive plasticity in vivo and how neuropeptide activity can represent a useful therapeutical target in a variety of human brain pathologies.

Lipopolysaccharide directly stimulates Th17 differentiation in vitro modulating phosphorylation of RelB and NF-κB1

Toll-like receptors (TLRs) recognize a wide range of pathogen-associated molecular patterns (PAMP) and are preferentially expressed in innate immune cells. TLR-mediated activation of these cells activates the adaptive immune system. However, it has become clear that TLRs are not only expressed but also functionally active in CD4 T cells. The intestines are continuously exposed to TLR ligands, including lipopolysaccharide (LPS), a TLR4 ligand, and TLR4 is expressed higher in Th17 cells than Th1 and Th2 cells. In addition, development of Th17 cells in the gut mucosa is more dependent on gut microbiota than Th1, Th2, and Treg. Thus, we examined whether LPS directly regulates Th17 differentiation. LPS directly stimulated Th17 differentiation in vitro. In Th17 cells, LPS increased phosphorylation of NF-κB1, resulting in an increase of p50, the processed form of NF-κB1, whereas it decreased phosphorylation of RelB, leading to the up-regulation of RelB. Subcutaneous injection of LPS increased the frequency of IL-17 producing cells in inguinal lymph nodes, worsening experimental autoimmune encephalomyelitis (EAE). Additionally, expression of TLR1, TLR2, TLR4, and TLR5 was reduced upon T cell activation and LPS showed modest effect on TLR4 expression. These findings provide the first evidence that TLR4 activation directly regulate Th17 differentiation.

The neuropeptide vasoactive intestinal peptide: direct effects on immune cells and involvement in inflammatory and autoimmune diseases

Neuropeptides represent an important category of endogenous contributors to the establishment and maintenance of immune deviation in the immune-privileged organs such as the CNS and in the control of acute inflammation in the peripheral immune organs. Vasoactive intestinal peptide (VIP) is a major immunoregulatory neuropeptide widely distributed in the central and peripheral nervous system. In addition to neurones, VIP is synthesized by immune cells which also express VIP receptors. Here, we review the current information on VIP production and VIP-receptor-mediated effects in the immune system, the role of endogenous and exogenous VIP in inflammatory and autoimmune disorders and the present and future VIP therapeutic approaches.

Transcriptional mechanisms and protein kinase signaling mediate organic dust induction of IL-8 expression in lung epithelial and THP-1 cells

Exposure to the agricultural work environment is a risk factor for the development of respiratory symptoms and chronic lung diseases. Inflammation is an important contributor to the pathogenesis of tissue injury and disease. Cellular and molecular mechanisms mediating lung inflammatory responses to agricultural dust are not yet fully understood. We studied the effects of poultry dust extract on molecular regulation of interleukin-8 (IL-8), a proinflammatory cytokine, in A549 and Beas2B lung epithelial and THP-1 monocytic cells. Our findings indicate that poultry dust extract potently induces IL-8 levels by increasing IL-8 gene transcription without altering IL-8 mRNA stability. Increase in IL-8 promoter activity was due to enhanced binding of activator protein 1 and NF-κB. IL-8 induction was associated with protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activation and inhibited by PKC and MAPK inhibitors. IL-8 increase was not inhibited by polymyxin B or l-nitroarginine methyl ester, indicating lack of involvement of lipopolysaccharide and nitric oxide in the induction. Lung epithelial and THP-1 cells share common mechanisms for induction of IL-8 levels. Our findings identify key roles for transcriptional mechanisms and protein kinase signaling pathways for IL-8 induction and provide insights into the mechanisms regulating lung inflammatory responses to organic dust exposure.

Future prospects of systemic host modulatory agents in periodontal therapy

Periodontitis is an inflammatory disease caused by microbial infection that leads to destruction of supporting tissues of the teeth. The periodontal tissue destruction is a result of both microbial activity as well as host response. The best chance for clinical improvement may come from implementing complementary treatment strategies that target different aspects of the periodontal balance. Host response modulation, in combination with conventional treatment, offers to restore the balance between health and disease progression in the direction of a healing response. Various host modulatory therapies (HMT) have been developed or proposed to block pathways responsible for periodontal tissue break down. The newer drugs like bortezomib, infliximb, etanercept, vasoactive intestinal peptide, nitric oxide synthase inhibitors and denosumab are developed as a result of better understanding of pathogenesis of inflammatory tissue destruction and may represent the future of periodontal therapy. This review article focuses on the potential systemic host modulatory agents that target cell signalling pathways, cytokines and enzymes.

The effects of neurotrophins and the neuropeptides VIP and PACAP on HIV-1 infection: histories with opposite ends

The nerve growth factor (NGF) and other neurotrophins, and the neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) are largely present in human tissue and can exert modulatory activities on nervous, endocrine and immune system functions. NGF, VIP and PACAP receptors are expressed systemically in organisms, and thus these mediators exhibit pleiotropic natures. The human immunodeficiency virus type 1 (HIV-1), the causal agent of the acquired immunodeficiency syndrome (AIDS), infects immune cells, and its replication is modulated by a number of endogenous factors that interact with HIV-1-infected cells. NGF, VIP and PACAP can also affect HIV-1 virus particle production upon binding to their receptors on the membranes of infected cells, which triggers cell signaling pathways that modify the HIV-1 replicative cycle. These molecules exert opposite effects on HIV-1 replication, as NGF and other neurotrophins enhance and VIP and PACAP reduce viral production in HIV-1-infected human primary macrophages. The understanding of AIDS pathogenesis should consider the mechanisms by which the replication of HIV-1, a pathogen that causes chronic morbidity, is influenced by neurotrophins, VIP and PACAP, i.e. molecules that exert a broad spectrum of physiological activities on the neuroimmunoendocrine axis. In this review, we will present the main effects of these two groups of mediators on the HIV-1 replicative cycle, as well as the mechanisms that underlie their abilities to modulate HIV-1 production in infected immune cells, and discuss the possible repercussion of the cross talk between NGF and both neuropeptides on the pathogenesis of HIV-1 infection.

OK-432-stimulated chemokine secretion from human monocytes depends on MEK1/2, and involves p38 MAPK and NF-κB phosphorylation, in vitro

Interaction between the immune system and cancer cells allows for the use of biological response modifiers, like OK-432, in cancer therapy. We have studied the involvement of monocytes (MOs) in the immune response to OK-432 by examining MCP-1, MIP-1α and MIP-1β secretion, in vitro. OK-432-induced IL-6/TNF-α secretion has previously been shown to depend on mitogen-activated protein kinases (MAPKs) ERK1/2 and p38, and we therefore investigated the role of these MAPKs in OK-432-induced chemokine secretion. Here we demonstrate that pharmacological MEK1/2 kinase inhibition generally impaired chemokine secretion from MOs, whereas p38 MAPK inhibition in particular reduced MIP-1α production. Furthermore, simultaneous inhibition of MEK1/2 and Syk kinase was seen to have an additive impact on reduced MCP-1, MIP-1α and MIP-1β secretion. Based on single cell flow cytometry analyses, OK-432, lipoteichoic acid (LTA) and lipopolysaccharide (LPS) were seen to induce p38 MAPK and NF-κB phosphorylation in MOs with different time kinetics. LTA and LPS have been shown to induce ERK1/2 phosphorylation, whereas the levels of phosphorylated ERK1/2 remained constant following OK-432 treatment at the time points tested. Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns, and we demonstrate increased TLR2 cell surface levels on the MO population, most profoundly following stimulation with LTA and OK-432. Together these results indicate that modulation of MEK1/2 and p38 MAPK signalling could affect the response to OK-432 treatment, having the potential to improve its therapeutic potential within cancer and lymphangioma treatment.

Vasoactive intestinal peptide downregulates proinflammatory TLRs while upregulating anti-inflammatory TLRs in the infected cornea

TLRs recognize microbial pathogens and trigger an immune response, but their regulation by neuropeptides, such as vasoactive intestinal peptide (VIP), during Pseudomonas aeruginosa corneal infection remains unexplored. Therefore, C57BL/6 (B6) mice were injected i.p. with VIP, and mRNA, protein, and immunostaining assays were performed. After VIP treatment, PCR array and real-time RT-PCR demonstrated that proinflammatory TLRs (conserved helix-loop-helix ubiquitous kinase, IRAK1, TLR1, TLR4, TLR6, TLR8, TLR9, and TNFR-associated factor 6) were downregulated, whereas anti-inflammatory TLRs (single Ig IL-1-related receptor [SIGIRR] and ST2) were upregulated. ELISA showed that VIP modestly downregulated phosphorylated inhibitor of NF-κB kinase subunit α but upregulated ST2 ~2-fold. SIGIRR was also upregulated, whereas TLR4 immunostaining was reduced in cornea; all confirmed the mRNA data. To determine whether VIP effects were cAMP dependent, mice were injected with small interfering RNA for type 7 adenylate cyclase (AC7), with or without VIP treatment. After silencing AC7, changes in mRNA levels of TLR1, TNFR-associated factor 6, and ST2 were seen and unchanged with addition of VIP, indicating that their regulation was cAMP dependent. In contrast, changes were seen in mRNA levels of conserved helix-loop-helix ubiquitous kinase, IRAK1, 2, TLR4, 9 and SIGIRR following AC7 silencing alone; these were modified by VIP addition, indicating their cAMP independence. In vitro studies assessed the effects of VIP on TLR regulation in macrophages and Langerhans cells. VIP downregulated mRNA expression of proinflammatory TLRs while upregulating anti-inflammatory TLRs in both cell types. Collectively, the data provide evidence that VIP downregulates proinflammatory TLRs and upregulates anti-inflammatory TLRs and that this regulation is both cAMP dependent and independent and involves immune cell types found in the infected cornea.

Effects of 1,25-(OH)(2)D (3) on the expressions of vitamin D receptor, STAT5 and cytoskeletal rearrangement in human monocytes incubated with sera from type 2 diabetes patients and diabetic nephropathy patients with uremia

OBJECTIVE

To explore the effects of 1,25-(OH)(2)D(3) and lipopolysaccharide (LPS) plus human recombinant interleukin-15 (IL-15) on expression of vitamin D receptor (VDR) and STAT5, and cytoskeletal rearrangement in human monocytes incubated with sera from type 2 diabetes (T2DM) patients and diabetic nephropathy (DN) patients with uremia.

MATERIALS AND METHODS

Peripheral sera were isolated from healthy volunteers (control group, T2DM patients and DN uremic non-dialysis patients). After incubation with or without 1,25(OH)(2)D(3), THP-1 monocytes were treated with LPS plus IL-15 prior to the collection of cells and supernatants. VDR mRNA transcription was examined by RT-PCR, whilst THP-1 monocytic VDR, STAT5 and p-STAT5 expressions were investigated by Western blotting. Concentrations of IL-6 and monocyte chemoattractant protein-1 (MCP-1) in supernatants were assessed by ELISA. Immunofluorescence and a laser confocal microscopy was used to examine the expression of VDR and cytoskeletal proteins.

RESULTS

Compared to the normal control, LPS and IL-15 down-regulate monocytic VDR expression in T2DM patients and DN uremic patients, whilst with cytoskeletal rearrangement, they up-regulate p-STAT5 expression as well as IL-6 and MCP-1 activity. Such effects could be in part blocked by 1,25-(OH)(2)D(3).

CONCLUSION

The above results suggest that the anti-inflammatory mechanism of 1,25-(OH)(2)D(3) may be related to cytoskeletal proteins, VDR and STAT5 signaling pathway.

Toll-like receptor stimulation differentially regulates vasoactive intestinal peptide type 2 receptor in macrophages

Vasoactive intestinal peptide (VIP) was originally isolated as a vasodilator intestinal peptide, then as a neuropeptide. In the immune system, VIP is described as an endogenous macrophage-deactivating factor. VIP exerts its immunological actions in a paracrine and/or autocrine manner, through specific receptors. However, very little is known about the molecular regulation of VIP type 2 receptor (VPAC(2)) in the immune system. We now report that different toll-like receptor (TLR) ligands selectively regulate the VPAC(2) receptor gene and show a gene repression system controlled by key protein kinase signalling cascades in macrophages. VPAC(2) gene expression is regulated by gram-positive (TLR2 ligands) and gram-negative bacteria wall constituents (TLR4 ligands). Moreover, VPAC(2) is tightly regulated: TLR2- or TLR2/6- but not TLR2/1-mediated mechanisms are responsible for the induction of VPAC(2). TLR stimulation by viral or bacterial nucleic acids did not modify the VPAC(2) mRNA levels. Remarkably, imiquimod--a synthetic TLR7 ligand--led to a potent up-regulation of VPAC(2) gene expression. TLR5 stimulation by flagellin present in gram-positive and gram-negative bacteria did not affect VPAC(2) mRNA. The p38 mitogen-activated protein kinase (MAPK) activity accounted for the TLR4-mediated induction of VPAC(2) gene expression. Surprisingly, our data strongly suggest for the first time a tightly repressed control of VPAC(2) mRNA induction by elements downstream of MAPK kinase 1/2, PI3K/Akt, and particularly Jun-NH(2)-terminal kinase signalling pathways.

Vasoactive intestinal peptide: a neuropeptide with pleiotropic immune functions

Vasoactive intestinal peptide (VIP), a 28-amino acid neuropeptide/neurotransmitter, is widely distributed in both the central and peripheral nervous system. VIP is released by both neurons and immune cells. Various cell types, including immune cells, express VIP receptors. VIP has pleiotropic effects as a neurotransmitter, immune regulator, vasodilator and secretagogue. This review is focused on VIP production and effects on immune cells, VIP receptor signaling as related to immune functions, and the involvement of VIP in inflammatory and autoimmune disorders. The review addresses present clinical use of VIP and future therapeutic directions.

Inflammation-induced up-regulation of TLR2 expression in human endothelial cells is independent of differential methylation in the TLR2 promoter CpG island

Toll-like receptors play an important role in endothelial inflammation; however, little is known on the mechanisms regulating their expression. Differential promoter DNA methylation is an increasingly recognized mechanism that determines a switch between gene silencing and gene transcription. We hypothesized that epigenetic mechanisms are involved in the regulation of endothelial TLR2 expression because of the localization of the TLR2 promoter on a CpG-island. Resting human umbilical vein endothelial cells (HUVECs) displayed rather low TLR2 mRNA expression, while a strong expression increase occurred under inflammatory conditions. We examined the TLR2 promoter methylation pattern in resting HUVECs and compared it to cells treated either with the inflammatory cytokine TNF-α or the DNA-demethylating agent 5-azacytidine. DNA bisulfite conversion was followed by either genomic sequencing or single nucleotide primer extension (SNuPE) HPLC. Results of both techniques showed a low- or non-methylated TLR2 promoter in resting HUVECs and no alteration of the methylation pattern under inflammatory conditions. Whereas 5-azacytidine significantly increased the mRNA expression of the epigenetically regulated gene H19, TLR2 expression was not affected. Taken together, employing different methodological approaches, our data show no implication of methylation pattern changes in inflammatory induction of TLR2 expression in human endothelial cells.

Transcriptional modulation by VIP: a rational target against inflammatory disease

Vasoactive intestinal peptide (VIP) is a pleiotropic, highly conserved, peptide found in many different biological systems throughout invertebrate phyla. VIP is produced by cells of the immune system but also inhibits many different inflammatory products produced by these immune cells, including cytokines and chemokines. VIP inhibits these immune mediators by affecting transcriptional regulators such as NFκB and activator protein 1 which transcribes genes responsible for the production of inflammatory mediators in response to pathogens or cytokines. In this review, the therapeutic potential of VIP will be discussed in the context of transcriptional regulation of immune cells in in vitro and in vivo animal models.

Azithromycin may inhibit interleukin-8 through suppression of Rac1 and a nuclear factor-kappa B pathway in KB cells stimulated with lipopolysaccharide

BACKGROUND

Recent studies have shown that the 15-member macrolide antibiotic azithromycin (AZM) not only has antibacterial activity, but also results in the role of immunomodulator. Interleukin (IL)-8 is an important inflammatory mediator in periodontal disease. However, there have been no reports on the effects of AZM on IL-8 production from human oral epithelium. Therefore, we investigated the effects of AZM on IL-8 production in an oral epithelial cell line.

METHODS

KB cells were stimulated by Escherichia coli or Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) lipopolysaccharide (LPS) with or without AZM. IL-8 mRNA and protein expression and production in response to LPS were analyzed by quantitative polymerase chain reaction, flow cytometry, and enzyme-linked immunosorbent assay. The activation of nuclear factor-kappa B (NF-κB) and Rac1, which is important for IL-8 expression, was analyzed by enzyme-linked immunosorbent assay and Western blotting, respectively.

RESULTS

IL-8 mRNA expression, IL-8 production, and NF-κB activation in LPS-stimulated KB cells were inhibited by the addition of AZM. LPS-induced Rac1 activation was also suppressed by AZM.

CONCLUSIONS

This study suggests that AZM inhibits LPS-induced IL-8 production in an oral epithelial cell line, in part caused by the suppression of Rac1 and NF-κB activation. The use of AZM might provide possible benefits in periodontal therapy, with respect to both its antibacterial action and apparent anti-inflammatory effect.

Differential expression of toll-like receptors in patients with irritable bowel syndrome

OBJECTIVES

The pathogenesis of irritable bowel syndrome (IBS) is poorly understood. One contributory factor may be low-grade mucosal inflammation, perhaps initiated by the microbiota. Toll-like receptors (TLRs) are a family of pathogen-recognition receptors of the innate immune system. The aim of this study was to evaluate the potential involvement of TLRs in IBS to further understand the involvement of the innate immune system in this complex disorder.

METHODS

The expression of TLRs was investigated in colonic biopsy samples obtained from 26 IBS patients and compared with 19 healthy controls. Protein expression of TLR4, TLR7, and TLR8 was confirmed by immunofluorescence and alterations in the TLR4 protein were confirmed by western blot.

RESULTS

Quantitative reverse transcriptase-PCR showed increased levels of TLR4 (P≤0.001) and TLR5 (P=0.0013) and decreased levels of TLR7 (P≤0.001) and TLR8 (P=0.0019) in IBS patients.

CONCLUSIONS

Our results support the presence of an immune engagement between the microbiota and the host in IBS; an interaction that involves innate immunity and could generate a low-grade inflammatory response. These findings could also offer an additional biomarker of the disease or a disease subset.

Immunomodulation of innate immune responses by vasoactive intestinal peptide (VIP): its therapeutic potential in inflammatory disease

Since the late 1970s a number of laboratories have studied the role of vasoactive intestinal peptide (VIP) in inflammation and immunity. These studies have highlighted the dramatic effect of VIP on immune cell activation and function, and studies using animal models of disease have indicated that VIP has significant therapeutic and prophylactic potential. This review will focus on the effects of VIP on innate immune cell function and discuss the therapeutic potential for VIP in inflammatory diseases of humans.

Differential expression of immunoregulatory genes in monocytes in response to Porphyromonas gingivalis and Escherichia coli lipopolysaccharide

Porphyromonas gingivalis lipopolysaccharide (LPS) (strain W50) interacts with Toll-like receptor 2 (TLR-2) leading to cytokine expression and inflammation, and thereby plays a key role in the pathogenesis of periodontal disease. The aims of this study were to investigate gene expression of key regulatory mediators of innate immune responses in a human monocytic cell line (THP-1) to P. gingivalis LPS and to compare these results with those obtained using the TLR-4 ligand, Escherichia coli LPS. Custom-made Taqman low-density arrays were used for expression profiling of 45 different cytokine-related genes. Both types of LPS highly up-regulated interleukin (IL)-1alpha and IL-1beta, IL-18 receptor (IL-18R), IL-18R accessory protein and IL-1 family (IL-1F)9. Expression levels of IL-1F6, IL-1F7 and caspase-1 were unaltered by either LPS. Genes for tumour necrosis factor-alpha, IL-6, leukaemia inhibitory factor and IL-32 were also highly induced by both LPS. For a subset of genes, including CXC chemokine ligand 5 (CXCL5), expression was induced only by E. coli LPS or was up-regulated more highly by E. coli compared with P. gingivalis LPS in THP-1 monocytes. A similar expression pattern was also observed in dendritic cells. Analysis of signalling pathways which lead to CXCL5 expression indicated that the mechanisms underpinning the differential responses did not involve the recruitment of different adaptor proteins by TLR-2 and TLR-4, and therefore occur downstream of the receptor-adaptor complex. We conclude that differences in signalling pathways activated by TLR-2 and TLR-4 ligands lead to differential innate immune responses which may be important in polymicrobial diseases such as periodontal disease.

The transcriptional network that controls growth arrest and differentiation in a human myeloid leukemia cell line

Using deep sequencing (deepCAGE), the FANTOM4 study measured the genome-wide dynamics of transcription-start-site usage in the human monocytic cell line THP-1 throughout a time course of growth arrest and differentiation. Modeling the expression dynamics in terms of predicted cis-regulatory sites, we identified the key transcription regulators, their time-dependent activities and target genes. Systematic siRNA knockdown of 52 transcription factors confirmed the roles of individual factors in the regulatory network. Our results indicate that cellular states are constrained by complex networks involving both positive and negative regulatory interactions among substantial numbers of transcription factors and that no single transcription factor is both necessary and sufficient to drive the differentiation process.

Cytokine profiling using monocytes/macrophages cultured on common biomaterials with a range of surface chemistries

Cytokines, chemokines, and growth factors were assayed from the supernatants of monocytes and macrophages cultured on common biomaterials with a range of surface chemistries. TNF-alpha, MCP-1, MIP-1alpha, IL-8, IL-6, IL-1beta, VEGF, IL-1ra, and IL-10 were measured from monocyte/macrophage cultures at different stages of activation and differentiation seeded onto polyethylene, polyurethane, expanded polytetrafluoroethylene, polymethyl methacrylate, and a hydrogel copolymer of 2-hydroxyethyl methacrylate, 1-vinyl-2-pyrrolidinone, and polyethylene glycol acrylate in tissue culture polystyrene (TCPS) plates. Empty TCPS wells and organo-tin polyvinyl chloride served as "blanks" and positive controls, respectively. Results showed an overall increase in cytokine, chemokine, and growth factor production as monocytes are activated or differentiated into macrophages and that proinflammatory and anti-wound healing cytokines and chemokines dominate this profile. However, cytokine production was only modestly affected by the surface chemistry of these four stable and noncytotoxic biomaterials.

The contribution of the synovium, synovial derived inflammatory cytokines and neuropeptides to the pathogenesis of osteoarthritis

Osteoarthritis (OA) is one of the most common and disabling chronic joint disorders affecting horses, dogs and humans. Synovial inflammation or synovitis is a frequently observed phenomenon in osteoarthritic joints and contributes to the pathogenesis of OA through formation of various catabolic and pro-inflammatory mediators altering the balance of cartilage matrix degradation and repair. Catabolic mediators produced by the inflamed synovium include pro-inflammatory cytokines, nitric oxide, prostaglandin E(2) and several neuropeptides, which further contribute to the pathogenesis of OA by increasing cartilage degradation. Recent studies suggest that substance P, corticotropin-releasing factor, urocortin and vasoactive intestinal peptide may also be involved in OA development, but the precise role of these neuropeptides in the pathogenesis of OA is not known. Since increased production of matrix metalloproteinases by the synovium is stimulated by pro-inflammatory cytokines, future anti-inflammatory therapies should focus on the synovium as a means of controlling subsequent inflammatory damage.

A functional polymorphism of the vasoactive intestinal peptide receptor 1 gene correlates with the presence of HLA-B*2705 in Sardinia

The association of HLA-B27 with ankylosing spondylitis (AS) is the strongest among all inflammatory diseases. However, the exact role of these molecules in disease pathogenesis is still unknown. The existence of HLA-B27 variants rarely found in patients introduces a further level of complexity. It is now accepted that other genes of minor impact contribute to modify disease susceptibility and these genes might be diverse in different populations depending on the genetic background. We report here a study performed in Sardinia, an outlier population in which two major HLA-B27 subtypes are present, B (*)2705 strongly associated with AS and B (*)2709 which is not, and show the co-occurrence of the B (*)2705 allele with a single nucleotide polymorphism (SNP) mapping at 3'-UTR of the receptor 1 (VIPR1) for the vasoactive intestinal peptide (VIP), a neuropeptide with anti-inflammatory properties. This same SNP is associated with a different kinetics of down-modulation of the VIPR1 mRNA in monocytes after exposure to lipopolysaccharide (P=0.004). This particular setting, HLA-B (*)2705 and a functional polymorphism in VIPR1 gene, might be due to a founder effect or might be the result of a selective pressure. Irrespectively, the consequent downregulation of this receptor in the presence of a 'danger' signal might influence susceptibility to AS.

VIP balances innate and adaptive immune responses induced by specific stimulation of TLR2 and TLR4

Crohn's disease (CD) is a chronic intestinal inflammatory pathology, which develops as a result of innate immune signals, such as the activation of Toll-like receptors (TLRs), and adaptive immune signals, including Th1 cytokine release. We have recently demonstrated in TNBS-induced colitis, a murine model of CD, that VIP plays a homeostatic role, by reducing TNBS-induced TLR2 and TLR4 expression to control levels. The purpose of this paper is to elucidate for the first time, the physiological relevance of VIP specific control of innate and adaptive immune responses through TLR2 and TLR4 ligands. In addition, we investigated the effect of VIP on regulatory activity of T regulatory (Treg) cells in the TNBS-colitis model. First, we found that VIP downregulated the inflammatory response elicited in mesenteric lymph node cell cultures by treatment with the TLR2 ligand Pam3Cys, or the TLR4 ligand lipopolysaccharide (LPS), reducing the production of the chemokine CXCL1. Also, treatment with VIP impaired the induction of Th1 responses by decreasing p70 interleukin (IL)-12 and interferon gamma (IFN-gamma) levels after TLR2/TLR4 stimulation in culture. Besides, VIP treatment restored in vivo the numbers of TLR2 and TLR4 positive CD4+CD25+ T lymphocytes, augmented by TNBS administration, and increased the expression of molecules involved in regulatory T cell function, such as Foxp3 and TGF-beta. In conclusion, the ability of VIP to down-regulate uncontrolled inflammation by targeting TLR-mediated responses and regulatory T cell activity could be used as a new alternative therapy for intestinal inflammatory/autoimmune disorders.

VIP reverses the expression profiling of TLR4-stimulated signaling pathway in rheumatoid arthritis synovial fibroblasts

Since recent evidences point out the potential involvement of Toll-like receptors (TLRs) in the therapeutic effect of vasoactive intestinal peptide (VIP), the purpose of this study is to elucidate the role of VIP as a negative regulator of TLR-signaling. To this aim, we analyzed in fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) or osteoarthritis (OA), the expression profile of TLR-pathway related molecules, as well as the alterations induced by LPS stimulation in RA-FLS and the effect of VIP treatment. Cultured FLS were obtained from patients with RA or OA. RA-FLS were next stimulated with lipopolysaccharide (LPS) in presence or absence of VIP. The gene expression profiling of molecules involved in LPS-mediated TLR4-signaling was studied by cRNA microarray analysis. Twenty three molecules involved in TLR signaling resulted over-expressed at mRNA level in basal RA-FLS compared to OA-FLS. Moreover, in RA-FLS, 23 of the analyzed genes were found to be up-regulated by LPS stimulation whereas 30 were not affected. VIP down-regulated the LPS-induced RNA expression of molecules involved in TLR signaling pathway. Up-regulation of RNA expression of CD14, MD2, TRAM, TRIF, IRAK4, TAB2, TRAF6 and TBK1 was corroborated by RT-PCR as well as the VIP regulatory effect. Increased protein levels of TRAF6, TBK1 and pIRAK1 after exposure to LPS, and the inhibitory effect of VIP, were described by Western blotting. As functional consequences, it was observed the VIP-induced impaired production of IL-6 and RANTES/CCL5 after LPS stimulation. In conclusion, VIP acts as a negative modulator of the TLR4-signaling by overturning the production of several checkpoints molecules of the cascade and thus, widening its potential therapeutic effects.

Toll-like receptor 4 and cytokine expression involved in functional immune response in an originally established porcine intestinal epitheliocyte cell line

To study the immune responses of porcine intestinal epithelial cells to gram-negative bacteria via toll-like receptors (TLRs), originally established porcine intestinal epitheliocyte (PIE) cells were treated with lipopolysaccharide (LPS) or swine-specific enterotoxigenic Escherichia coli (ETEC). Real-time quantitative PCR revealed that PIE cells expressed TLR1-9 and MD-2 mRNAs, preferentially expressed TLR4/MD-2. Immunostaining of PIE cells revealed that TLR4 was precisely expressed in PIE cells at the protein level. PIE cells treated with LPS had up-regulated expression of several TLRs (TLR2, 3, 4, 5 and 8), type 1 helper T (Th1) cytokines (interleukin (IL)-1alpha, IL-1beta, IL-6, IL-15, 18, leukemia inhibitory factor (LIF), and interferon (IFN)-beta), and chemokines (monocyte chemoattractant protein (MCP)-1 and IL-8). ETEC enhanced the expression of TLR2, Th1 type cytokines (IL-1alpha, IL-12p35 and IL-6) and chemokines (MCP-1 and IL-8). These results indicate that PIE induces inflammatory responses by up-regulating Th1 cytokines and chemokines in response to LPS or ETEC, suggesting that PIE is a useful cell line for studying inflammatory responses via TLR4/MD-2 in intestinal epithelial cells.

Regulation of TLR expression, a new perspective for the role of VIP in immunity

The contribution of VIP immune functions to the regulation of homeostasis and health is well known. Modulation of immune responses through new therapeutics is one of the main goals of physicians and scientists seeking to control inflammatory/autoimmune diseases in humans. Initial therapeutic strategies targeted adaptive immune responses; discovery of Toll-like receptors (TLR) has widened the horizon to include targeting the innate immune system. In this review we have summarized recent information about VIP modulation of TLR function, and we suggest that VIP represents a new therapeutic option in the management of several pathologies.