Interleukin 10 protects mice from lethal endotoxemia

Alpha-melanocyte-stimulating hormone contributes to an anti-inflammatory response to lipopolysaccharide

OBJECTIVE

During infection, metabolism and immunity react dynamically to promote survival through mechanisms that remain unclear. Pro-opiomelanocortin (POMC) cleavage products are produced and released in the brain and in the pituitary gland. One POMC cleavage product, alpha-melanocyte-stimulating hormone (α-MSH), is known to regulate food intake and energy expenditure and has anti-inflammatory effects. However, it is not known whether α-MSH is required to regulate physiological anti-inflammatory responses. We recently developed a novel mouse model with a targeted mutation in Pomc (Pomctm1/tm1 mice) to block production of all α-MSH forms which are required to regulate metabolism. To test whether endogenous α-MSH is required to regulate immune responses, we compared acute bacterial lipopolysaccharide (LPS)-induced inflammation between Pomctm1/tm1 and wild-type Pomcwt/wt mice.

METHODS

We challenged 10- to 14-week-old male Pomctm1/tm1 and Pomcwt/wt mice with single i.p. injections of either saline or low-dose LPS (100 μg/kg) and monitored immune and metabolic responses. We used telemetry to measure core body temperature (Tb), ELISA to measure circulating cytokines, corticosterone and α-MSH, and metabolic chambers to measure body weight, food intake, activity, and respiration. We also developed a mass spectrometry method to measure three forms of α-MSH produced in the mouse hypothalamus and pituitary gland.

RESULTS

LPS induced an exaggerated immune response in Pomctm1/tm1 compared to Pomcwt/wt mice. Both groups of mice were hypoactive and hypothermic following LPS administration, but Pomctm1/tm1 mice were significantly more hypothermic compared to control mice injected with LPS. Pomctm1/tm1 mice also had reduced oxygen consumption and impaired metabolic responses to LPS compared to controls. Pomctm1/tm1 mice had increased levels of key proinflammatory cytokines at 2 h and 4 h post LPS injection compared to Pomcwt/wt mice. Lastly, Pomcwt/wt mice injected with LPS compared to saline had increased total α-MSH in circulation 2 h post injection.

CONCLUSIONS

Our data indicate endogenous α-MSH contributes to the inflammatory immune responses triggered by low-dose LPS administration and suggest that targeting the melanocortin system could be a potential therapeutic for the treatment of sepsis or inflammatory disease.

Sonic vibration ameliorates inflammatory diseases via the up-regulation of IL-10

Sonic vibration (SV), or vibroacoustic therapy, is applied to enhance local and systemic blood circulation and alleviate pain using low-frequency sine wave vibrations. However, there is limited scientific data on the mechanisms through which the benefits are achieved. In this study, we investigated the impact of SV on inflammatory responses by assessing cytokine secretion in both in vivo and in vitro models. After inducing inflammatory responses in mice and macrophages, we studied cytokine expression and the symptoms of inflammatory diseases in response to three frequencies (14, 45, or 90 Hz) of SV stimulation at 0.5 m/s2 of amplitude. The results showed that SV at 90 Hz significantly increased interelukin-10 (IL-10) secretion in mice who were administered lipopolysaccharides (LPS) and increased the expression of IL-10 transcripts in peritoneal exudate cells and macrophages. Furthermore, SV at 90 Hz improved LPS-induced lethality and alleviated symptoms in a colitis model. In conclusion, this study scientifically proves the anti-inflammatory effects of vibration therapy through its ability to increase IL-10 expression.

NAD+ prevents septic shock-induced death by non-canonical inflammasome blockade and IL-10 cytokine production in macrophages

Septic shock is characterized by an excessive inflammatory response depicted in a cytokine storm that results from invasive bacterial, fungi, protozoa, and viral infections. Non-canonical inflammasome activation is crucial in the development of septic shock promoting pyroptosis and proinflammatory cytokine production via caspase-11 and gasdermin D (GSDMD). Here, we show that NAD+ treatment protected mice toward bacterial and lipopolysaccharide (LPS)-induced endotoxic shock by blocking the non-canonical inflammasome specifically. NAD+ administration impeded systemic IL-1β and IL-18 production and GSDMD-mediated pyroptosis of macrophages via the IFN-β/STAT-1 signaling machinery. More importantly, NAD+ administration not only improved casp-11 KO (knockout) survival but rendered wild type (WT) mice completely resistant to septic shock via the IL-10 signaling pathway that was independent from the non-canonical inflammasome. Here, we delineated a two-sided effect of NAD+ blocking septic shock through a specific inhibition of the non-canonical inflammasome and promoting immune homeostasis via IL-10, underscoring its unique therapeutic potential.

Effect of IL-10 and TNF-α on the competence and cryosurvival of in vitro produced Bos indicus embryos

In vitro-produced embryos are constantly exposed to stressful conditions that can lead to the activation of the apoptotic pathway. The nuclear Kappa B factor (NF-κB) is an inflammatory mediator that induces the expression of tumor necrosis factor (TNF-α), a pro-inflammatory cytokine, while interleukin-10 (IL-10), an anti-inflammatory cytokine, inhibits NF-κB activity. This study aimed to investigate the effects of IL-10 and TNF-α on the competence and cryosurvival of in vitro-produced bovine embryos. Embryos were produced in vitro using standard protocols, and Grade I blastocysts were vitrified using the Cryotop method. Non-vitrified and vitrified blastocysts were subjected to the TUNEL assay. In Experiment I, on day 6.5 (156 h post-insemination), the embryos were treated with PBS (control), 50 ng/mL of IL-10, or a combination of 25 ng/mL of TNF-α and 50 ng/mL of IL-10. Embryonic development and apoptotic rates were monitored. In Experiment II, the same groups were set up, with the addition of a group treated with 25 ng/mL of TNF-α alone. Grade I blastocysts were vitrified 5 h after treatment, and cryosurvival was monitored at until 48 h post-warming. The apoptosis rate and total cell number were investigated in the vitrified-hatched blastocysts. IL-10 alone did not affect developmental competence or cryosurvival (P > 0.05). The IL-10-treated embryos, when exposed in combination with TNF-α, presented a detrimental effect (P < 0.05) in the embryonic development of non-vitrified embryos. However, vitrified blastocysts had no negative effect (P > 0.05). The TNF-α treatment reduced (P < 0.05) the re-expansion rate at 6 h post-warming and increased (P < 0.05) the apoptosis rate in vitrified hatched blastocysts, whereas no effect (P > 0.05) of the treatments was detected in the hatching rate and total cell number post-warming. In conclusion, TNF-α has a detrimental effect on embryonic developmental competence and cryosurvival by compromising the development of non-vitrified embryos and apoptotic-related events of vitrified blastocysts, whereas IL-10, when in combination with TNF-α, appears to attenuate the detrimental effects of TNF-α.

The Mechanisms of Action of Hyperbaric Oxygen in Restoring Host Homeostasis during Sepsis

The perception of sepsis has shifted over time; however, it remains a leading cause of death worldwide. Sepsis is now recognized as an imbalance in host cellular functions triggered by the invading pathogens, both related to immune cells, endothelial function, glucose and oxygen metabolism, tissue repair and restoration. Many of these key mechanisms in sepsis are also targets of hyperbaric oxygen (HBO2) treatment. HBO2 treatment has been shown to improve survival in clinical studies on patients with necrotizing soft tissue infections as well as experimental sepsis models. High tissue oxygen tension during HBO2 treatment may affect oxidative phosphorylation in mitochondria. Oxygen is converted to energy, and, as a natural byproduct, reactive oxygen species are produced. Reactive oxygen species can act as mediators, and both these and the HBO2-mediated increase in oxygen supply have the potential to influence the cellular processes involved in sepsis. The pathophysiology of sepsis can be explained comprehensively through resistance and tolerance to infection. We argue that HBO2 treatment may protect the host from collateral tissue damage during resistance by reducing neutrophil extracellular traps, inhibiting neutrophil adhesion to vascular endothelium, reducing proinflammatory cytokines, and halting the Warburg effect, while also assisting the host in tolerance to infection by reducing iron-mediated injury and upregulating anti-inflammatory measures. Finally, we show how inflammation and oxygen-sensing pathways are connected on the cellular level in a self-reinforcing and detrimental manner in inflammatory conditions, and with support from a substantial body of studies from the literature, we conclude by demonstrating that HBO2 treatment can intervene to maintain homeostasis.

The Tissue Response to Hypoxia: How Therapeutic Carbon Dioxide Moves the Response toward Homeostasis and Away from Instability

Sustained tissue hypoxia is associated with many pathophysiological conditions, including chronic inflammation, chronic wounds, slow-healing fractures, microvascular complications of diabetes, and metastatic spread of tumors. This extended deficiency of oxygen (O₂) in the tissue sets creates a microenvironment that supports inflammation and initiates cell survival paradigms. Elevating tissue carbon dioxide levels (CO₂) pushes the tissue environment toward "thrive mode," bringing increased blood flow, added O₂, reduced inflammation, and enhanced angiogenesis. This review presents the science supporting the clinical benefits observed with the administration of therapeutic CO₂. It also presents the current knowledge regarding the cellular and molecular mechanisms responsible for the biological effects of CO₂ therapy. The most notable findings of the review include (a) CO₂ activates angiogenesis not mediated by hypoxia-inducible factor 1a, (b) CO₂ is strongly anti-inflammatory, (c) CO₂ inhibits tumor growth and metastasis, and (d) CO₂ can stimulate the same pathways as exercise and thereby, acts as a critical mediator in the biological response of skeletal muscle to tissue hypoxia.

Recombinant Human Thrombomodulin Reduces Mortality and Acute Lung Injury Caused by Septic Peritonitis in Rats

This study aimed to investigate the therapeutic effects of recombinant human thrombomodulin (rhTM) on acute lung injury (ALI) caused by sepsis in rats. Rats that underwent cecal ligation and puncture (CLP) were treated with or without rhTM, and then mortality was analyzed. In another set of experiments, ALI was assessed. Furthermore, microthrombosis in the lungs was investigated by immunohistochemistry. Moreover, plasma inflammatory and anti-inflammatory cytokines, such as TNF-α, high-mobility group box chromosomal protein 1 (HMGB-1), and IL-10, were evaluated by ELISA. Production of TNF-α and HMGB-1 by isolated tissue macrophages (Mφs) was assessed in vitro. Mortality after CLP was significantly improved by rhTM treatment. In addition, rhTM treatment improved the wet/dry weight ratio of the lungs, the pulmonary microvascular permeability, and the lung injury scores in animals that underwent CLP. Microthrombosis was detected in the lungs after CLP. These pathophysiological changes were blunted by rhTM treatment. Increased plasma TNF-α and HMGB-1 levels were blunted by rhTM treatment; however, the anti-inflammatory cytokine IL-10 was significantly greater in the rhTM(+) group than in the rhTM(-) group. Increased TNF-α and HMGB-1 production by the tissue Mφs stimulated with LPS were significantly blunted by rhTM treatment in vitro, but the production of IL-10 by the tissue Mφs was not changed in the cells incubated with rhTM. Overall, rhTM improved the mortality caused by septic peritonitis. The possible mechanisms are most likely anti-inflammatory and anticoagulant effects, which lead to the prevention of ALI.

Thymoquinone modulates the expression of sepsis‑related microRNAs in a CLP model

Sepsis is a clinical syndrome common in critical care settings. In the present study, the therapeutic effect of thymoquinone (TQ) on the expression of sepsis-related microRNAs (miRNAs/miRs), levels of inflammatory markers, organ dysfunction and mortality were investigated in a cecal ligation and puncture (CLP) rat model. A single dose of TQ (1 mg/kg) was administered to animals 24 h after CLP and the mortality rate was assessed up to 7 days following the induction of sepsis. In addition, blood samples were collected at different time points and the expression levels of miRNAs (i.e. miR-16, miR-21, miR-27a and miR-34a) were examined, along with the levels of inflammatory cytokines (i.e. TNF-α, IL-1α, IL-2, IL-6 and IL-10) and sepsis markers (i.e. C-reactive protein, endothelial cell-specific molecule-1, VEGF, procalcitonin and D-dimer). Liver, kidney and lung tissues were also collected for further histological examination. Treatment with TQ significantly downregulated the miRNA expression levels, as well as the levels of inflammatory cytokines and early-stage sepsis biomarkers by 30-70% at 12-36 h (P<0.05). Furthermore, CLP model rats treated with TQ exhibited an ~80% increase in survival rate compared with that in the untreated CLP group. In addition, TQ induced the preservation of organ function and structure. In conclusion, the present study demonstrated a promising therapeutic effect of TQ against the sequelae of sepsis.

Pyruvate dehydrogenase kinase is a negative regulator of interleukin-10 production in macrophages

Interleukin-10 (IL-10) is the most potent anti-inflammatory cytokine in the body and plays an essential role in determining outcomes of many inflammatory diseases. Cellular metabolism is a critical determinant of immune cell function; however, it is currently unclear whether metabolic processes are specifically involved in IL-10 production. In this study, we aimed to find the central metabolic molecule regulating IL-10 production of macrophages, which are the main producers of IL-10. Transcriptomic analysis identified that metabolic changes were predominantly enriched in Kupffer cells at the early inflammatory phase of a mouse endotoxemia model. Among them, pyruvate dehydrogenase kinase (PDK)-dependent acute glycolysis was negatively involved in IL-10 production. Inhibition or knockdown of PDK selectively increased macrophage IL-10 expression. Mechanistically, PDK inhibition increased IL-10 production via profound phosphorylation of adenosine monophosphate (AMP)-activated protein kinase alpha 1 (AMPKα1) by restricting glucose uptake in lipopolysaccharide-stimulated macrophages. AMPKα1 consequently activated p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, and cyclic AMP-responsive element-binding protein to regulate IL-10 production. Our study uncovers a previously unknown regulatory mechanism of IL-10 in activated macrophages involving an immunometabolic function of PDK.

Synthesis, characterization & evaluation of venom neutralization potential of silver nanoparticles mediated Alstonia scholaris Linn bark extract

OBJECTIVE

The venom neutralization potential of silver nanoparticle(AgNP-AS) mediated bark extract of Alstonia scholaris Linn R.Br was investigated in the study.

METHODS & MATERIALS

AgNP-AS was synthesized with respect to optimal temperature, pH of extract. UV-vis, FT-IR, XRD, TEM, SEM studies were used to characterize silver nanoparticles of Alstonia scholaris Linn(AgNP-AS). The potential of AgNP-AS in neutralization of venom lethality, rise in myotoxicity markers(LDH) and proinflammatory cytokines(IL6, TNFα) were evaluated in animal models.

RESULTS

AgNP-AS was synthesized optimally with AgNO3 (2 mM); extract concentration, 0.2 gm/l (1% w/v); extract (pH 9) and optimal temperature (40 °C). The colour change and synthesis of AgNP-AS was validated by UV-vis analysis at 432 nm. Transmission electron microscopy of AgNP-AS showed that the particle size for AgNP-AS was 14 nm-20 nm. FT-IR revealed peaks at 3445 cm-1, 1646 cm-1, 1346 cm-1 and 1108 cm-1. From the dynamic light scattering studies the hydrodynamic diameter (115.87 nm) and zeta potential(-29.8 mV) were estimated. The EDAX exhibited a peak for silver validating that the synthesized silver was pure. The biosynthesized (AgNP-AS) could significantly neutralize Viper russelli venom(VRV) induced rise in serum lactate dehydrogenase(LDH) and proinflammatory cytokines(IL6, TNFα) in animal models.

CONCLUSION

The culmination of nanotechnology with herbal medicine might endow with a really constructive tool in coming up with future drugs with fewer toxicity.

Imipenem alters systemic and liver inflammatory responses in CLP- induced sepsis mice in a dose-dependent manner

BACKGROUND

Considering the role of inflammation in the outcome of sepsis and the widespread use of imipenem in the disease, this study was designed to assess the effect of imipenem on the dynamics of inflammatory responses in the sepsis mouse model.

METHODS

Cecal Ligation and Puncture (CLP) model was used to induce sepsis in mice. C57BL/6 mice were divided into sham, CLP-induced sepsis mice, CLP-induced sepsis mice receiving 25 mg/kg, and 125 mg/kg imipenem. Blood and liver samples were obtained and bacterial load, endotoxin level, and liver enzymes were evaluated. The concentration and mRNA expression of cytokines were also determined.

RESULTS

Sepsis mice treated with a high dose (125 mg/kg) of imipenem showed a significant reduction in bacterial load, while increased liver enzymes, endotoxin level, and inflammatory cytokine production in plasma and liver. In contrast, significant reduction in the liver enzymes, bacterial load, endotoxin levels, and inflammatory cytokine levels was observed in the mice treated with a low dose (25 mg/kg) of imipenem compared with other mice groups. Liver tissue pathology of mice indicated little tissue destruction in the sepsis mice treated with 25 mg/kg of imipenem compared to other groups. Mice receiving 25 mg/kg of imipenem had better survival rate.

CONCLUSIONS

Our results demonstrated the dose-dependent effect of subcutaneous administration of imipenem on the inflammatory responses in sepsis mice. A dose of 25 mg/kg imipenem resulted in better pathology, lower inflammatory mediators, and increased survival rate in sepsis mice.

Apoptosis inhibitor of macrophage (AIM) contributes to IL-10-induced anti-inflammatory response through inhibition of inflammasome activation

Apoptosis inhibitor of macrophage (AIM) modulates the signaling in inflammatory responses, including infection, cancer, or other immune diseases. Recent studies suggest that like interleukin-10 (IL-10), AIM is involved in alternatively activated (M2) macrophage polarization. We aimed to understand whether and how AIM is involved in IL-10-induced inhibition of inflammasome activation and resolution of inflammation. First, we demonstrated that IL-10 induced increases in mRNA and protein expression of AIM in murine bone marrow-derived macrophages (BMDM). In addition, genetic and pharmacologic inhibition of STAT3 (signal transducer and activator of transcription 3) reduced IL-10-induced AIM expression. We also found that IL-10-induced STAT3 activity enhanced the AIM promoter activity by directly binding the promoter of the AIM gene. Additionally, reduction of LPS/adenosine triphosphate (ATP)-induced IL-1β production and caspase-1 activation by IL-10 was reversed in BMDM from AIM^-/- mice. Treatment of BMDM from both wild type (WT) and IL-10^-/- mice with recombinant AIM showed the inhibitory effects on IL-1β and IL-18 production and caspase-1 activation. Endogenous and exogenous AIM inhibited apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC) speck formation. In LPS-induced acute peritonitis, inhibition of IL-1β and IL-18 production in peritoneal lavage fluid (PLF) and serum, reduction of caspase-1 activation in peritoneal macrophages, and reduction of numbers of neutrophils and peritoneal macrophages in PLF by administration of IL-10 were not evident in AIM^-/- mice. Our in vitro and in vivo data reveal a novel role of AIM in the inhibition of inflammasome-mediated caspase-1 activation and IL-1β and IL-18 production.

Diet-induced obesity attenuates the hypothermic response to lipopolysaccharide independently of TNF-α production

Life-threatening infections (sepsis) are usually associated with co-morbidities, among which obesity deserves attention. Here, we evaluated whether and how obesity affects the switch from fever to hypothermia that occurs in the most severe cases of sepsis, which is thought to provide physiological support for a change in host defense strategy from resistance to tolerance. Obesity was induced by keeping rats on a high-fat diet for 32-34 weeks. The hypothermia induced by a high dose of bacterial lipopolysaccharide (LPS, 300 μg/animal, i.a.) was attenuated in the obese rats, as compared to their low-fat diet counterparts. Surprisingly, such attenuation occurred in spite of an enhancement in the circulating level of TNF-α, the most renowned mediator of LPS-induced hypothermia. Hence, it seems that factors counteracting not the production, but rather the action of TNF-α are at play in rats with diet-induced obesity. One of these factors might be IL-1β, a febrigenic mediator that also had its circulating levels augmented in the obese rats challenged with LPS. Taken together with previous reports of diet-induced obesity enhancing the fever induced by lower doses of LPS, the results of the present study indicate that obesity biases host defense toward a fever/resistance strategy, in lieu of a hypothermia/tolerance strategy.

Interleukin 35 Delays Hindlimb Ischemia-Induced Angiogenesis Through Regulating ROS-Extracellular Matrix but Spares Later Regenerative Angiogenesis

Interleukin (IL) 35 is a novel immunosuppressive heterodimeric cytokine in IL-12 family. Whether and how IL-35 regulates ischemia-induced angiogenesis in peripheral artery diseases are unrevealed. To fill this important knowledge gap, we used loss-of-function, gain-of-function, omics data analysis, RNA-Seq, in vivo and in vitro experiments, and we have made the following significant findings: i) IL-35 and its receptor subunit IL-12RB2, but not IL-6ST, are induced in the muscle after hindlimb ischemia (HLI); ii) HLI-induced angiogenesis is improved in Il12rb2-/- mice, in ApoE-/-/Il12rb2-/- mice compared to WT and ApoE-/- controls, respectively, where hyperlipidemia inhibits angiogenesis in vivo and in vitro; iii) IL-35 cytokine injection as a gain-of-function approach delays blood perfusion recovery at day 14 after HLI; iv) IL-35 spares regenerative angiogenesis at the late phase of HLI recovery after day 14 of HLI; v) Transcriptome analysis of endothelial cells (ECs) at 14 days post-HLI reveals a disturbed extracellular matrix re-organization in IL-35-injected mice; vi) IL-35 downregulates three reactive oxygen species (ROS) promoters and upregulates one ROS attenuator, which may functionally mediate IL-35 upregulation of anti-angiogenic extracellular matrix proteins in ECs; and vii) IL-35 inhibits human microvascular EC migration and tube formation in vitro mainly through upregulating anti-angiogenic extracellular matrix-remodeling proteins. These findings provide a novel insight on the future therapeutic potential of IL-35 in suppressing ischemia/inflammation-triggered inflammatory angiogenesis at early phase but sparing regenerative angiogenesis at late phase.

Myeloperoxidase instigates proinflammatory responses in a cecal ligation and puncture rat model of sepsis

Myeloperoxidase (MPO)-derived hypochlorous (HOCl) reacts with membrane plasmalogens to yield α-chlorofatty aldehydes such as 2-chlorofatty aldehyde (2-ClFALD) and its metabolite 2-chlorofatty acid (2-ClFA). Recent studies showed that 2-ClFALD and 2-ClFA serve as mediators of the inflammatory responses to sepsis by as yet unknown mechanisms. Since no scavenger for chlorinated lipids is available and on the basis of the well-established role of the MPO/HOCl/chlorinated lipid axis in inflammatory responses, we hypothesized that treatment with MPO inhibitors (N-acetyl lysyltyrosylcysteine amide or 4-aminobenzoic acid hydrazide) would inhibit inflammation and proinflammatory mediator expression induced by cecal ligation and puncture (CLP). We used intravital microscopy to quantify in vivo inflammatory responses in Sham and CLP rats with or without MPO inhibition. Small intestines, mesenteries, and lungs were collected to assess changes in MPO-positive staining and lung injury, respectively, as well as free 2-ClFA and proinflammatory mediators levels. CLP caused neutrophil infiltration, 2-ClFA generation, acute lung injury, leukocyte-/platelet-endothelium interactions, mast cell activation (MCA), plasminogen activator inhibitor-1 (PAI-1) production, and the expression of several cytokines, chemokines, and vascular endothelial growth factor, changes that were reduced by MPO inhibition. Pretreatment with a PAI-1 inhibitor or MC stabilizer prevented CLP-induced leukocyte-endothelium interactions and MCA, and abrogated exogenous 2-ClFALD-induced inflammatory responses. Thus, we provide evidence that MPO instigates these inflammatory changes in CLP and that chlorinated lipids may serve as a mechanistic link between the enzymatic activity of MPO and PAI-1- and mast cell-dependent adhesive interactions, providing a rationale for new therapeutic interventions in sepsis.NEW & NOTEWORTHY Using two distinct myeloperoxidase (MPO) inhibitors, we show for the first time that MPO plays an important role in producing increases in free 2-chlorofatty aldehyde (2-ClFALD)-a powerful proinflammatory chlorinated lipid in plasma and intestine-a number of cytokines and other inflammatory mediators, leukocyte and platelet rolling and adhesion in postcapillary venules, and lung injury in a cecal ligation and puncture model of sepsis. In addition, the use of a plasminogen activator inhibitor-1 (PAI-1) inhibitor or a mast cell stabilizer prevented inflammatory responses in CLP-induced sepsis. PAI-1 inhibition also prevented the proinflammatory responses to exogenous 2-ClFALD superfusion. Thus, our study provides some of the first evidence that MPO-derived free 2-ClFA plays an important role in CLP-induced sepsis by a PAI-1- and mast cell-dependent mechanism.

Gravidity-dependent associations between interferon response and birth weight in placental malaria

BACKGROUND

Maternal malarial infection leads to poor perinatal outcomes, including low birth weight from preterm delivery and/or fetal growth restriction, particularly in primigravidas. In placental malaria, Plasmodium falciparum-infected red blood cells cause an inflammatory response that can interfere with maternal-fetal exchange, leading to poor growth. The type I interferon (IFN-I) pathway plays an immunomodulatory role in viral and bacterial infections, usually by suppressing inflammatory responses. However, its role in placental malaria is unknown. This study examines the cytokine responses in placental tissue from subsets of malaria-infected and uninfected women, and attempts to correlate them with particular birth outcomes.

METHODS

40 whole placental biopsy samples were obtained from pregnant women at least 16 years of age recruited to a larger prospective chemoprevention trial against malaria. These were patients at Tororo District Hospital in Uganda, an area of high malaria endemicity where approximately 40% of women have evidence of malaria infection at delivery. They were regularly followed at a local clinic and monitored for fever, with blood smears performed then and at time of delivery to diagnose malaria infection. Placenta biopsies were taken for histological diagnosis of placental malaria, as well as quantitative PCR analysis of genes in the IFN-I pathway (IFN-β, IL-10 and MX-1). Parameters such as infant birth weight and gestational age were also recorded.

RESULTS

Histological analysis revealed placental malaria in 18 samples, while 22 were found to be uninfected. RT-PCR analysis showed a four-fold increase in IFN-β and IL-10 expression in multigravidas with placental malaria when compared to gravidity-matched, uninfected controls. This effect was not observed in primigravidas. Interestingly, linear regression analysis showed a positive association between IFN-β levels and higher birth weights (β = 101.2 g per log2-fold increase in IFN-β expression, p = 0.042). This association was strongest in primigravidas with placental malaria (β = 339.0, p = 0.006).

CONCLUSIONS

These results demonstrate differential regulation of the IFN-I pathway in placental malaria according to gravidity, with the greatest anti-inflammatory response seen in multigravidas. The association between IFN-β levels and higher birth weight also suggests a protective role for IFN-I against fetal growth restriction in placental malaria.

Nemonoxacin Has Immunoprotective Effects on Reducing Mortality in Lipopolysaccharide-Induced Mouse Sepsis Model

Nemonoxacin is a novel non-fluorinated quinolone. The effect of nemonoxacin on modulation of host immune response is not known. We sought to determine whether nemonoxacin has immunoprotective effects on lipopolysaccharide (LPS)-induced mouse sepsis model. Therefore, mice were challenged with lethal dose LPS (12.5 mg/kg) only or LPS with multi-dose nemonoxacin (40 mg/kg q12h) by intraperitoneal injection, and the results showed nemonoxacin could significantly reduce mortality from 80 to 30% in this model. The effect of nemonoxacin on immune cells in vivo and in vitro was also investigated. Mice were treated with sublethal LPS (5 mg/kg) or LPS + nemonoxacin, the myeloid cell subsets in mouse spleen were analyzed by flow cytometry, and cytokines in mouse serum were measured by ELISA. Additionally, mouse macrophage RAW264.7 cells were treated with LPS or LPS + nemonoxacin to investigate the immune modulatory effect of nemonoxacin in vitro, and the level of cytokines in cell culture supernatant was determined by ELISA. Analysis of myeloid cell subsets in the spleen showed nemonoxacin pretreatment could significantly inhibit LPS-induced proliferation of macrophages and dendritic cells but have no effect on neutrophils. Nemonoxacin could significantly reduce the expression of pro-inflammatory cytokines IL-6 and TNF-α while increase anti-inflammatory cytokine IL-10 expression, which were induced by LPS in vivo and in vitro. Finally, the immunomodulation of nemonoxacin in macrophage phagocytosis was also examined. The results displayed nemonoxacin pretreatment could significantly enhance the phagocytic function of macrophage. In conclusion, nemonoxacin has immune modulatory and protective effect on LPS-induced inflammation in vivo and in vitro.

Tissue-resident macrophages actively suppress IL-1beta release via a reactive prostanoid/IL-10 pathway

The alarm cytokine interleukin‐1β (IL‐1β) is a potent activator of the inflammatory cascade following pathogen recognition. IL‐1β production typically requires two signals: first, priming by recognition of pathogen‐associated molecular patterns leads to the production of immature pro‐IL‐1β; subsequently, inflammasome activation by a secondary signal allows cleavage and maturation of IL‐1β from its pro‐form. However, despite the important role of IL‐1β in controlling local and systemic inflammation, its overall regulation is still not fully understood. Here we demonstrate that peritoneal tissue‐resident macrophages use an active inhibitory pathway, to suppress IL‐1β processing, which can otherwise occur in the absence of a second signal. Programming by the transcription factor Gata6 controls the expression of prostacyclin synthase, which is required for prostacyclin production after lipopolysaccharide stimulation and optimal induction of IL‐10. In the absence of secondary signal, IL‐10 potently inhibits IL‐1β processing, providing a previously unrecognized control of IL‐1β in tissue‐resident macrophages.

OroxylinA reverses lipopolysaccharide-induced adhesion molecule expression and endothelial barrier disruption in the rat aorta

Vascular dysfunction plays a critical role in the pathogenesis of sepsis. We elucidated the mechanisms underlying the amelioration of lipopolysaccharide (LPS)-induced vascular inflammation by oroxylin A (OroA) post-treatment in rats. The animals were intraperitoneally injected with LPS (10 mg/kg) to induce systemic inflammation and intravenously (iv) administered OroA (15 mg/kg) 6 h after the LPS treatment. The assessments included biochemical changes in peripheral blood, vascular reactivity which was evaluated by blood-vessel myography, morphological/histological assessment of inflammation, toll-like receptor (TLR)-4-mediated interleukin-1-receptor-associated-kinase (IRAK)-4 activation, changes in adhesion molecule expression, and endothelial junctional stability in the aorta. LPS significantly enhanced the proinflammatory cytokine release, increased vascular cell adhesion molecule (VCAM)-1 expression, disrupted endothelial tight junction, reduced vascular endothelial barrier stability, and increased macrophage infiltration and accumulation in the aorta. All observed pathological changes and vascular inflammation were significantly reversed by the OroA post-treatment. Importantly, OroA suppressed the increased adhesion molecule expression and the endothelial barrier disruption by inhibiting LPS-activated IRAK-4-targeted inhibitory nuclear factor kappa B kinase (IKK) α/β complex phosphorylation, without directly affecting the interaction between LPS and TLR-4. Moreover, the iNOS activity induced by the LPS challenge was inhibited by the OroA pretreatment of the isolated aortic rings. These results suggest that OroA regulates the vascular tone by inhibiting vascular hyporeactivity caused by NO overproduction and reverses the endothelial barrier dysfunction and inflammation by inhibiting the IRAK-4-mediated IKKα/β phosphorylation. Overall, these findings suggest OroA administration as a potentially useful therapeutic approach for clinical interventions in septic shock.

Inhibitory Effects of Carrageenans on Endotoxin-Induced Inflammation

The inhibitory effects of carrageenans (CRGs) on lipopolysaccharide (LPS) induced inflammation in a mouse model of endotoxemia and in complex therapy of patients with enteric infections of Salmonella etiology were studied. The atomic force microscopy (AFM) examination of LPS and its mixture with CRGs showed that the LPS morphology is significantly changed under the action of κ- and κ/β-CRGs. CRGs were able to increase the synthesis of anti-inflammatory interleukin 10 (IL-10) in vitro, and, at low concentrations, their activity in the mixture with LPS was higher. The protective effect of CRGs against Escherichia coli LPS was studied in vivo by monitoring the biochemical and pathomorphological parameters. The κ- and κ/β-CRGs and food supplement "Carrageenan-FE" increased the nonspecific resistance of mice to E. coli LPS at the expense of the inhibition of processes of thymus involution, adrenals hypertrophy, thyroid atrophy, hypercorticoidism, glycogenolysis, and lactate acidosis. The estimation of the therapeutic action of food supplement Carrageenan-FE in complex therapy of patients with enteric infections of Salmonella etiology is given. Carrageenan-FE restores the system of hemostasis and corrects some biochemical indicators and parameters in the immune systems of patients. These results allow us to hope for the practical application of CRGs for lowering the endotoxemia level in patients under the development of the infectious process caused by Gram-negative bacteria.

Biomarkers of Immunosuppression

It is now recognized that sepsis is not a uniformly proinflammatory state. There is a well-recognized counter anti-inflammatory response that occurs in many patients. The timing and magnitude of this response varies considerably and thus makes its identification and manipulation more difficult. Studies in animals and humans have now identified a small number of biologic responses that characterize this immunosuppressed state, such as lymphocyte death, HLA receptor downregulation, and monocyte exhaustion. Researchers are now trying to use these as markers of individual immunosuppression to predict outcomes and identify patients who would and would not benefit from new immune stimulatory therapies.

Modulation of transcriptomic profile in aquatic animals: Probiotics, prebiotics and synbiotics scenarios

Aquaculture and fisheries have provided protein sources for human consumption for a long time, but diseases have induced declines in product benefits and raised concerns, resulting in great losses to these industries in many countries. The overuse of antibiotics for the treatment of diseases has increased the chemical concentrations in culture systems and weakened the natural immunity of aquatic organisms. Concerns regarding the detrimental effects of antibiotics on the environment and human health due to residual antibiotic-related issues encourage the development of reliable, environmental and health safety methods, such as vaccines, probiotics, prebiotics, synbiotics and phytobiotics, for protection against disease and for reducing and possibly eliminating disease occurrence. Immunity has been effectively enhanced by pro-, pre-, and synbiotics, which confer strong protection and reduce the risks associated with stressors and disease outbreaks in culture systems. These agents confer several benefits, including enhancing both host growth and immune responses against pathogens, while sustaining health and environmental stability, and their use is thus widely accepted. Alterations in gene expression in individual cells could serve as an indicator of the immunity and growth rate of aquatic animals after pro-, pre- and synbiotic feeding. This review addresses the potential use of pro, pre- and synbiotics as immunostimulants for improved aquaculture management and environmental health and chronicles the recent insights regarding the application of pro-, pre- and synbiotics with special emphasis on their immunomodulatory and antioxidative responses based on gene expression changes. Furthermore, the current review describes the research gaps and other issues that merit further investigation.

IL-10 Has Differential Effects on the Innate and Adaptive Immune Systems of Septic Patients

Sepsis, a disease of divergent pro- and anti-inflammatory-mediated pathways, has a high prevalence of morbidity and mortality, yet an understanding of potential unifying mediators between these pathways that may improve clinical outcomes is largely unclear. IL-10 has classically been designated an immunosuppressive cytokine, although recent data suggest that under certain conditions IL-10 can be immune stimulatory. We sought to further investigate the effect of IL-10 on innate and adaptive immunity in an in vitro human observational cohort study in patients with sepsis via modulation of IL-10 on IFN-γ production by T cells and TNF-α production and HLA-DR expression by monocytes. These results were compared with critically ill nonseptic patients and healthy volunteers. ELISpot analysis was performed using PBMC fraction from patient whole-blood samples. Finally, to provide additional potential clinical relevance, we examined the effect of IL-10 on T cell IFN-γ production in an in vivo cecal ligation and puncture model of sepsis using C57 black/J6 female mice. We found that inhibition of IL-10 significantly increased both production of T cell IFN-γ and monocyte TNF-α, whereas addition of IL-10 increased T cell IFN-γ production but decreased monocyte production of TNF-α and HLA-DR expression. There was no significant effect of IL-10 on control cohorts. IL-10-treated septic mice demonstrated increased IFN-γ production in splenocytes. Thus, IL-10 demonstrates both pro- and anti-inflammatory effects in the septic microenvironment, which is likely cell and context dependent. Further elucidation of relevant signaling pathways may direct future therapeutic targets.

Nitidine chloride exerts anti-inflammatory action by targeting Topoisomerase I and enhancing IL-10 production

In the effort to identify natural products that regulate immunity and inflammation, we found that nitidine chloride (NC), an alkaloid from herb Zanthoxylum nitidum, enhanced IL-10 production in lipopolysaccharide (LPS)-stimulated myeloid cells. While NC was shown to be capable of inhibiting topoisomerase I (TOP1), NC analogs that could not inhibit TOP1 failed to increase IL-10 production. Moreover, medicinal TOP1 inhibitors TPT and SN-38 also augmented IL-10 production significantly, whereas knockdown of TOP1 prevented NC, TPT, and SN-38 from enhancing IL-10 expression. Thus, NC promoted IL-10 production by inhibiting TOP1. In LPS-induced endotoxemic mice, NC and TOP1 inhibitors increased IL-10 production, suppressed inflammatory responses, and reduced mortality remarkably. The anti-inflammatory activities of TOP1 inhibition were markedly reduced by IL-10-neutralizing antibody and largely absent in IL-10-deficient mice. In LPS-stimulated RAW264.7 cells and in peritoneal macrophages from endotoxemic mice, NC and TOP1 inhibitors significantly enhanced the activation of Akt, a critical signal transducer for IL-10 production, and inhibition of Akt prevented these compounds from enhancing IL-10 production and ameliorating endotoxemia. These data indicated that NC and TOP1 inhibitors are able to exert anti-inflammatory action through enhancing Akt-mediated IL-10 production and may assist with the treatment of inflammatory diseases.

Alnus Sibirica Extracts Suppress the Expression of Inflammatory Cytokines Induced by Lipopolysaccharides, Tumor Necrosis Factor-α, and Interferon-γ in Human Dermal Fibroblasts

The effects of Alnus sibirica (AS) extracts on cytokine expression induced by inflammatory stimulants were examined in human dermal fibroblasts (HDFs) and RAW264.7 cells. The anti-oxidative effect and effect on cell viability of AS extracts were evaluated, and four extracts with the highest anti-oxidative effects were selected. HDFs and RAW264.7 cells were treated with inflammatory stimulants, and the expression of cytokines involved in acute (IL-6 and IL-10) and chronic (IL-18) inflammation, the initiation of the immune response (IL-33), and non-specific immune responses (IL-1β, IL-8, and TNF-α) were determined using a reverse-transcription polymerase chain reaction. LPS increased the expression of all the cytokines, except for IL-18; however, AS extracts, particularly AS2 and AS4, reduced this increase, and TNF-α treatment markedly increased the expression of cytokines related to non-specific immune responses. IFN-γ treatment induced no significant changes, except for increased IL-33 expression in HDFs. AS extracts inhibited the increase in the expression of IL-33 and other cytokines in HDFs. Thus, the exposure of HDFs and RAW264.7 cells to inflammatory stimulants increased the expression of cytokines related to all the inflammatory processes. HDFs are involved not only in simple tissue regeneration but also in inflammatory reactions in the skin. AS2 and AS4 may offer effective therapy for related conditions.

Immune regulation and cytotoxic T cell activation of IL-10 agonists - Preclinical and clinical experience

The expansion and activation of tumor antigen reactive CD8⁺ T cells are primary goals of immunotherapies for cancer. IL-10 is an anti-inflammatory cytokine with an essential role in the development and proliferation of regulatory T cells, restricting myeloid and chronic inflammatory T cell responses. However, IL-10 is also essential for the expansion of antigen activated, tumor specific CD8⁺ T cells, leading to spontaneous tumor development in IL-10 deficient patients and mice. IL-10 induces IFNγ and cytotoxic mediators in antigen activated T cells. In clinical trials, monotherapy with recombinant, pegylated IL-10 (Pegilodecakin) induced objective responses in cancer patients. Patients receiving pegilodecakin had a systemic increase of IFNγ and granzymes, proliferation and expansion of immune checkpoint positive CD8⁺ T cells. Combination of pegilodecakin with anti-PD-1 appeared to improve on the efficacy of the single agents.

Mesenchymal stromal cell-derived nanovesicles ameliorate bacterial outer membrane vesicle-induced sepsis via IL-10

Background

Sepsis remains a source of high mortality in hospitalized patients despite proper antibiotic approaches. Encouragingly, mesenchymal stromal cells (MSCs) and their produced extracellular vesicles (EVs) have been shown to elicit anti-inflammatory effects in multiple inflammatory conditions including sepsis. However, EVs are generally released from mammalian cells in relatively low amounts, and high-yield isolation of EVs is still challenging due to a complicated procedure. To get over these limitations, vesicles very similar to EVs can be produced by serial extrusions of cells, after which they are called nanovesicles (NVs). We hypothesized that MSC-derived NVs can attenuate the cytokine storm induced by bacterial outer membrane vesicles (OMVs) in mice, and we aimed to elucidate the mechanism involved.

Methods

NVs were produced from MSCs by the breakdown of cells through serial extrusions and were subsequently floated in a density gradient. Morphology and the number of NVs were analyzed by transmission electron microscopy and nanoparticle tracking analysis. Mice were intraperitoneally injected with Escherichia coli-derived OMVs to establish sepsis, and then injected with 2 × 10⁹ NVs. Innate inflammation was assessed in peritoneal fluid and blood through investigation of infiltration of cells and cytokine production. The biodistribution of NVs labeled with Cy7 dye was analyzed using near-infrared imaging.

Results

Electron microscopy showed that NVs have a nanometer-size spherical shape and harbor classical EV marker proteins. In mice, NVs inhibited eye exudates and hypothermia, signs of a systemic cytokine storm, induced by intraperitoneal injection of OMVs. Moreover, NVs significantly suppressed cytokine release into the systemic circulation, as well as neutrophil and monocyte infiltration in the peritoneum. The protective effect of NVs was significantly reduced by prior treatment with anti-interleukin (IL)-10 monoclonal antibody. In biodistribution study, NVs spread to the whole mouse body and localized in the lung, liver, and kidney at 6 h.

Conclusions

Taken together, these data indicate that MSC-derived NVs have beneficial effects in a mouse model of sepsis by upregulating the IL-10 production, suggesting that artificial NVs may be novel EV-mimetics clinically applicable to septic patients.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1352-4) contains supplementary material, which is available to authorized users.

Peripheral anti-inflammatory cytokine Interleukin-10 treatment mitigates interleukin-1β - induced anxiety and sickness behaviors in adult male rats

Pro-inflammatory cytokines produce manifestations of sickness during inflammation, such as malaise and lethargy. They also contribute to effects of inflammation on mood. Anti-inflammatory cytokines counteract damage caused by inflammatory processes and can limit the severity of inflammation. However, very little is known about the role of anti-inflammatory cytokines in sickness and mood changes during immune activation. The purpose of this study was to determine if a prototypical anti-inflammatory cytokine, interleukin 10 (IL-10), can offset sickness behavior and anxiety caused by a pro-inflammatory cytokine, and whether IL-10 itself modifies anxiety. Rodent models of sickness display suppression of behavioral activity that may reflect lethargy or malaise, while models of anxiety display reduced exploration in several tasks. The effects of peripheral single dose of cytokines on open field exploration, social interaction and elevated plus maze (EPM) tests in adult male Sprague-Dawley rats were measured at 30-50 min post-treatment. The prototypical pro-inflammatory cytokine IL-1β (1 μg, i.p.) caused a decrease in locomotor activity indicative of sickness behavior, but disproportionately reduced central area exploration in the open field, open arm exploration in the EPM and lowered social interaction. IL-10 (1 μg, i.p.) had no effect on locomotor activity, but itself produced anxiety-like behavior in the open field and EPM. However, rats co-treated with both IL-10 and IL-1β showed locomotor activity, open field, social interaction and EPM behaviors very similar to control groups. This data demonstrate that IL-10 is capable of mitigating the sickness and anxiogenic effects caused by IL-1β, but that immune imbalance toward either a pro-inflammatory or an anti-inflammatory state can produce anxiety. This has importance for understanding the scope of immune changes that produce psychiatric symptoms, and provides preliminary indication that anti-inflammatory cytokines may be potentially useful in treatment of anxiety induced by inflammatory conditions.

The pituitary gland prevents shock-associated death by controlling multiple inflammatory mediators

Bacterial infections cause a major burden of disease worldwide. Sepsis and septic shock are life-threatening complications of infections. The hypothalamic-pituitary-adrenal (HPA) axis initiates the release of endogenous glucocorticoids that modulate the host stress response and acute inflammation during septic shock. It is an ongoing controversial debate, if therapeutic manipulations of the HPA axis could benefit the clinical situation in the context of shock. Here, we have studied Long Evans rats with hypophysectomy followed by endotoxic shock. The shock-associated lethality was substantially higher in hypophysectomized rats as compared to control mice after cranial sham surgery (7-day survival rates: 27% vs. 89%). Fluorimetric bead-based assays were used to quantify the release of >20 cytokines and chemokines. The surgical removal of the pituitary gland resulted in greatly increased plasma concentrations of mediators such as IL-1α/IL-1β (10-12-fold), TNFα (19-fold), IL-6 (111-fold), IL-10 (10-fold) as well as the Th1 cytokines, Interferon-γ (8-fold), IL-12 (4-fold) and IL-18 (9-fold) after intra-peritoneal lipopolysaccharide (LPS) injections. In contrast, MIP-1α and Leptin were negatively associated with hypophysectomy. The Th2 cytokines, IL-4 and IL-13, as well as G-CSF, VEGF, IP-10 and RANTES were not significantly affected. The gene expression of the IL-6/IL-12 family cytokine, IL-27p28 was profoundly increased after pituitary gland removal followed by endotoxic shock. A dose-dependent reduction of LPS/TLR4-induced IL-27p28 release by glucococorticoids was observed in cultured rodent macrophages (C57BL/6J) as well as in vivo. This study reveals that the neuroendocrine influences of the HPA axis on the shock-associated inflammatory response are more selective and complex than previously known. These findings will be helpful to predict some of the consequences of therapeutic manipulations of the HPA in the context of sepsis and septic shock.

Meteorin-like/Meteorin-β Is a Novel Immunoregulatory Cytokine Associated with Inflammation

We have described a novel cytokine encoded by a gene called Meteorin-like (Metrnl). Metrnl is a small (∼28 kDa) secreted protein expressed by activated macrophages and barrier tissues (mucosa and skin). Metrnl production by bone marrow macrophages is induced by several cytokines including TNF-α, IL-17α, IL-12, and IL-4 and inhibited by IFN-γ and TGF-β. Metrnl expression in macrophages is also induced by LPS, and its levels in circulation are associated with inflammatory responses in vivo. Furthermore, Metrnl regulates the production of several cytokines and chemokines in macrophages. We have produced a Metrnl^-/- mouse, which is viable and shows normal development. However, it exhibits dysregulated cytokine production, alterations in IgG production, and is highly susceptible to LPS in a sepsis model. Furthermore, older Metrnl^-/- mice develop inflammatory lesions, suggesting that Metrnl participates in the control of inflammatory responses. Taken together, these observations indicate that Metrnl encodes a novel immunoregulatory cytokine associated with inflammatory responses that we have designated Meteorin-β.

Short-Term Hypoxia Dampens Inflammation in vivo via Enhanced Adenosine Release and Adenosine 2B Receptor Stimulation

Hypoxia and inflammation are closely intertwined phenomena. Critically ill patients often suffer from systemic inflammatory conditions and concurrently experience short-lived hypoxia. We evaluated the effects of short-term hypoxia on systemic inflammation, and show that it potently attenuates pro-inflammatory cytokine responses during murine endotoxemia. These effects are independent of hypoxia-inducible factors (HIFs), but involve augmented adenosine levels, in turn resulting in an adenosine 2B receptor-mediated post-transcriptional increase of interleukin (IL)-10 production. We translated our findings to humans using the experimental endotoxemia model, where short-term hypoxia resulted in enhanced plasma concentrations of adenosine, augmentation of endotoxin-induced circulating IL-10 levels, and concurrent attenuation of the pro-inflammatory cytokine response. Again, HIFs were shown not to be involved. Taken together, we demonstrate that short-term hypoxia dampens the systemic pro-inflammatory cytokine response through enhanced purinergic signaling in mice and men. These effects may contribute to outcome and provide leads for immunomodulatory treatment strategies for critically ill patients.

Temporal changes in macrophage phenotype after peripheral nerve injury

BACKGROUND

Macrophages play a key role in peripheral nerve repair and demonstrate complex phenotypes that are highly dependent on microenvironmental cues.

METHODS

We determined temporal changes in macrophage gene expression over time using RNA sequencing after fluorescence-activated cell sorting (FACS) macrophage populations from injured peripheral nerve. We identified key upstream regulators and dominant pathways using ingenuity pathway analysis and confirmed these changes with NanoString technology. We then investigate the effects of extreme polarizers of macrophage phenotype (IL4 and IFNγ) on nerve regeneration. We determined macrophage gene expression in vivo at the site of peripheral nerve injury with NanoString technology, and assessed recovery from sciatic nerve injury by cranial tibial muscle weights and retrograde labeling motor neurons in mice with deletion of IL4 or IFNγ receptors.

RESULTS

We demonstrate that IL4R and IFNγR deletions provide complementary responses to polarization, and alter expression of genes associated with angiogenesis and axonal extension, but do not influence recovery from peripheral nerve transection at 8 weeks after repair.

CONCLUSIONS

Overall, this study provides a framework to evaluate the phenotype of macrophages over time, and provides a broader and more precise assessment of gene expression changes than has previously been commonly used. This data suggests ways in which polarization may be modulated to improve repair.

Development and Characterization of an Endotoxemia Model in Zebra Fish

Endotoxemia is a condition in which endotoxins enter the blood stream and cause systemic and sometimes lethal inflammation. Zebra fish provides a genetically tractable model organism for studying innate immunity, with additional advantages in live imaging and drug discovery. However, a bona fide endotoxemia model has not been established in zebra fish. Here, we have developed an acute endotoxemia model in zebra fish by injecting a single dose of LPS directly into the circulation. Hallmarks of human acute endotoxemia, including systemic inflammation, extensive tissue damage, circulation blockade, immune cell mobilization, and emergency hematopoiesis, were recapitulated in this model. Knocking out the adaptor protein Myd88 inhibited systemic inflammation and improved zebra fish survival. In addition, similar alternations of pathways with human acute endotoxemia were detected using global proteomic profiling and MetaCore™ pathway enrichment analysis. Furthermore, treating zebra fish with a protein tyrosine phosphatase nonreceptor type 11 (Shp2) inhibitor decreased systemic inflammation, immune mobilization, tissue damage, and improved survival in the endotoxemia model. Together, we have established and characterized the phenotypic and gene expression changes of a zebra fish endotoxemia model, which is amenable to genetic and pharmacological discoveries that can ultimately lead to a better mechanistic understanding of the dynamics and interplay of the innate immune system.

Thymoquinone reduces mortality and suppresses early acute inflammatory markers of sepsis in a mouse model

BACKGROUND

Sepsis is a severe systemic condition caused by an excessive inflammatory response to microbial infections, which often results in high mortality.

AIMS

In the present study, the therapeutic effects of thymoquinone were investigated for Gram-negative bacteria-induced sepsis in mice.

METHODS

Thymoquinone was administered as 1or 2?mg/kg intraperitoneally 2?h after Escherichia coli (E. coli) challenge. Animal morality was assessed up to 96?h post infection and inflammatory proteins levels were measured 6?h after thymoquinone treatment in various groups using enzyme-linked immunosorbent assay (ELISA) techniques.

KEY FINDINGS

The E. coli inoculation markedly increased the level of plasma cytokines, including tumor necrosis factor (TNF)-?, interleukin (IL)-1, IL-2, IL-6 and IL-10. In addition, the levels of selected early sepsis biomarkers such as CRP, VEGF and ESM-1 were amplified in the septic group. Treatment with thymoquinone significantly downregulated the circulating concentrations of the inflammatory proteins (p?<?0.05). In addition, ?75% of mice in the thymoquinone (1?mg/kg) group survived at 96h of observation compared with ?8% of the untreated group (p?=?0.0016).

SIGNIFICANCE

The present results indicate that thymoquinone suppresses acute inflammatory responses induced by sepsis including early stage biomarkers and reduces sepsis-related mortality. These findings suggest that thymoquinone could be of a potential therapeutic value in the management of sepsis.

A high-fat, high-protein diet attenuates the negative impact of casein-induced chronic inflammation on testicular steroidogenesis and sperm parameters in adult mice

The interaction between obesity and chronic inflammation has been studied. Diet-induced obesity or chronic inflammation could reduce the testicular functions of males. However, the mechanism underlying the reproductive effects of fattening foods in males with or without chronic inflammation still needs further discussion. This study was aimed to investigate the effects of high-fat, high-protein diet on testicular steroidogenesis and sperm parameters in adult mice under physiological and chronic inflammatory conditions. Because casein can trigger a non-infectious systemic inflammatory response, we used casein injection to induce chronic inflammation in male adult Kunming mice. Twenty-four mice were randomly and equally divided into four groups: (i) normal diet+saline (Control); (ii) normal diet+casein (ND+CS); (iii) high-fat, high-protein diet+saline (HFPD+SI); (iv) high-fat, high-protein diet+casein (HFPD+CS). After 8weeks, there was a significant increase in body weight for groups HFPD+SI and HFPD+CS and a decrease in group ND+CS compared with the control. The serum levels of tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10) and lipid profiles were increased markedly in groups ND+CS, HFPD+SI and HFPD+CS compared with the control. A remarkable reduction of serum adiponectin level occurred in group HFPD+CS compared with group ND+CS. Sperm parameters (sperm count, viability and abnormality) were also adversely affected in groups ND+CS and HFPD+SI. Groups ND+CS and HFPD+SI showed severe pathological changes in testicular tissues. Semiquantitative RT-PCR, Western blot and immunohistochemical staining also showed significant reductions in both testicular mRNA and protein levels of steroidogenic acute regulatory (StAR) and cytochrome P450scc (CYP11A1) in groups HFPD+SI and HFPD+CS compared with the control, whereas testicular mRNA and protein levels of 3β-hydroxysteroid dehydrogenase (3β-HSD) in groups HFPD+SI and HFPD+CS significantly increased. The mRNA and protein levels of the StAR and 3β-HSD in group HFPD+CS were both higher than those of in group ND+CS. These results indicated that Kunming male mice with high-fat, high-protein diet and casein injection for 8weeks can be used to establish a diet-induced obesity and chronic systemic inflammation. The sperm parameters in groups ND+CS and HFPD+SI decreased accompanied by pathological changes of testicular tissue. This resultant effect of reduced serum testosterone levels was associated with the overproduction of TNF-α and IL-10 and down-regulation of StAR and CYP11A1. Under the same casein-induced chronic inflammation condition, the mice with high-fat, high-protein diet had better testicular steroidogenesis activity and sperm parameters compared with the mice in normal diet, indicating that the mice with casein-induced inflammatory injury consuming a high-fat, high-protein diet gained weight normally, reduced serum adiponectin level and increased testosterone production by an upregulation of 3β-HSD expression. High-fat, high-protein diet attenuated the negative impact of casein-induced chronic inflammation on testicular steroidogenesis and sperm parameters.

Pentoxifylline modulates LPS-induced hyperinflammation in monocytes of preterm infants in vitro

BackgroundPentoxifylline (PTX), a methylxanthine derivate with immunomodulating properties, has been used as adjunctive treatment in severe neonatal sepsis. The aim of the study was to investigate the anti-inflammatory effects of PTX on Lipopolysaccharides (LPS)-stimulated monocytes of preterm neonates in vitro compared with monocytes of term infants and adult controls.MethodsWhole cord blood samples and control adult blood samples were incubated with LPS and PTX. The expression of surface markers, phagocytosis, cytokine secretion, and Toll-like receptor (TLR)4 signaling of monocytes were assessed by flow cytometry. Changes of TLR4-messenger RNA (mRNA) levels were confirmed by reverse-transcriptase PCR.ResultsThe expression of CD14, CD11b, CD64, CD71, and CD80 was downregulated by PTX in a dose-dependent manner; the greatest effect was observed on CD14 and CD11b in preterm infants. PTX markedly downregulated LPS-induced tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 levels in all age groups. Early IL-10 production was significantly downregulated by PTX in term and preterm neonates, while remaining unchanged in adults. Moreover, PTX downregulated TLR4 expression of monocytes on cellular and mRNA level, decreased signaling, and suppressed phagocytosis.ConclusionPTX downregulated TLR4 expression and signaling, thereby leading to strong anti-inflammatory properties in monocytes. Age-dependent differences were identified for CD14 and CD11b expression and IL-10 production.

Systemic blockade of P2X7 receptor protects against sepsis-induced intestinal barrier disruption

Sepsis, during which the intestinal epithelial barrier is frequently disrupted, remains a challenging and life-threatening problem in clinical practice. The P2X7 receptor (P2X7R) is a non-selective adenosine triphosphate-gated cation channel present in macrophages that is involved in inflammatory responses. However, little is known about the role of P2X7R in macrophages during sepsis-induced intestinal barrier disruption. In this study, mice were treated with the P2X7R antagonist A740003 or the agonist BzATP by intra-peritoneal injection after the induction of gut-origin sepsis. The survival rates, inflammatory responses, intestinal barrier integrity, macrophage marker expression, and ERK and NF-κB activities were evaluated. Intestinal macrophages were also isolated and studied after exposure to Brilliant Blue G or BzATP. We found that a systemic P2X7R blockade downregulated sepsis-induced inflammatory responses and attenuated intestinal barrier dysfunction based on the evidence that mice in the A740003-treated group exhibited alleviated pro-inflammatory cytokine synthesis, intestinal hyperpermeability, epithelial apoptosis rates and tight junction damage compared with the septic mice. These changes were partly mediated by the inhibition of M1 macrophages activation via ERK/NF-κB pathways. Our data presented herein show that a P2X7R blockade could be a potential therapeutic target for the treatment of sepsis-induced intestinal barrier dysfunction.

Influence of carrageenan on cytokine production and cellular activity of mouse peritoneal macrophages and its effect on experimental endotoxemia

The in vivo effect of κ/β-carrageenan isolated from the red alga Tichocarpus crinitus on cytokine synthesis and cellular activity of murine peritoneal macrophages and also the protective effect of polysaccharides in LPS-induced endotoxemia in mice was studied. It was established that κ/β-carrageenan given orally at a dose of 100 mg/kg stimulates the induction of anti-inflammatory cytokines (IL-10) in mouse blood cells by more than 2.5-fold compared with control, with no effect on pro-inflammatory cytokine (TNF-α) production. Pretreating mice with carrageenan once a day before injecting LPS increased the levels of IL-10 by 2.5-fold and reduced TNF-α production by 2-fold compared with control. So, κ/β-carrageenan alone and in combination with LPS enhanced the cellular activity and mobility of peritoneal macrophages by increasing cell adhesion and migration compared with control. LPS activated cells intensively, sometimes resulting in their destruction by necrosis; carrageenan pretreatment reduced the excessive inflammatory cell activation caused by LPS. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1549-1557, 2017.

Defective Bone Repair in C57Bl6 Mice With Acute Systemic Inflammation

BACKGROUND

Bone repair is initiated with a local inflammatory response to injury. The presence of systemic inflammation impairs bone healing and often leads to malunion, although the underlying mechanisms remain poorly defined. Our research objective was to use a mouse model of cortical bone repair to determine the effect of systemic inflammation on cells in the bone healing microenvironment. QUESTION/PURPOSES: (1) Does systemic inflammation, induced by lipopolysaccharide (LPS) administration affect the quantity and quality of regenerating bone in primary bone healing? (2) Does systemic inflammation alter vascularization and the number or activity of inflammatory cells, osteoblasts, and osteoclasts in the bone healing microenvironment?

METHODS

Cortical defects were drilled in the femoral diaphysis of female and male C57BL/6 mice aged 5 to 9 months that were treated with daily systemic injections of LPS or physiologic saline as control for 7 days. Mice were euthanized at 1 week (Control, n = 7; LPS, n = 8), 2 weeks (Control, n = 7; LPS, n = 8), and 6 weeks (Control, n = 9; LPS, n = 8) after surgery. The quantity (bone volume per tissue volume [BV/TV]) and microarchitecture (trabecular separation and thickness, porosity) of bone in the defect were quantified with time using microCT. The presence or activity of vascular endothelial cells (CD34), macrophages (F4/80), osteoblasts (alkaline phosphatase [ALP]), and osteoclasts (tartrate-resistant acid phosphatase [TRAP]) were evaluated using histochemical analyses.

RESULTS

Only one of eight defects was bridged completely 6 weeks after surgery in LPS-injected mouse bones compared with seven of nine defects in the control mouse bones (odds ratio [OR], 0.04; 95% CI, 0.003-0.560; p = 0.007). The decrease in cortical bone in LPS-treated mice was reflected in reduced BV/TV (21% ± 4% vs 39% ± 10%; p < 0.01), increased trabecular separation (240 ± 36 μm vs 171 ± 29 μm; p < 0.01), decreased trabecular thickness (81 ± 18 μm vs 110 ± 22 μm; p = 0.02), and porosity (79% ± 4% vs 60% ± 10%; p < 0.01) at 6 weeks postoperative. Defective healing was accompanied by decreased CD34 (1.1 ± 0.6 vs 3.4 ± 0.9; p < 0.01), ALP (1.9 ± 0.9 vs 6.1 ± 3.2; p = 0.03), and TRAP (3.3 ± 4.7 vs 7.2 ± 4.0; p = 0.01) activity, and increased F4/80 (13 ± 2.6 vs 6.8 ± 1.7; p < 0.01) activity at 2 weeks postoperative.

CONCLUSION

The results indicate that LPS-induced systemic inflammation reduced the amount and impaired the quality of bone regenerated in mouse femurs. The effects were associated with impaired revascularization, decreased bone turnover by osteoblasts and osteoclasts, and by increased catabolic activity by macrophages.

CLINICAL RELEVANCE

Results from this preclinical study support clinical observations of impaired primary bone healing in patients with systemic inflammation. Based on our data, local administration of VEGF in the callus to stimulate revascularization, or transplantation of stem cells to enhance bone turnover represent potentially feasible approaches to improve outcomes in clinical practice.

RAGE-Mediated Suppression of Interleukin-10 Results in Enhanced Mortality in a Murine Model of Acinetobacter baumannii Sepsis

The receptor for advanced glycation end products (RAGE) is a pattern recognition receptor capable of recognizing multiple pathogen-associated and danger-associated molecular patterns that contributes to the initiation and potentiation of inflammation in many disease processes. During infection, RAGE functions to either exacerbate disease severity or enhance pathogen clearance depending on the pathogen studied. Acinetobacter baumannii is an opportunistic human pathogen capable of causing severe infections, including pneumonia and sepsis, in impaired hosts. The role of RAGE signaling in response to opportunistic bacterial infections is largely unknown. In murine models of A. baumannii pneumonia, RAGE signaling alters neither inflammation nor bacterial clearance. In contrast, RAGE^-/- mice systemically infected with A. baumannii exhibit increased survival and reduced bacterial burdens in the liver and spleen. The increased survival of RAGE^-/- mice is associated with increased circulating levels of the anti-inflammatory cytokine interleukin-10 (IL-10). Neutralization of IL-10 in RAGE^-/- mice results in decreased survival during systemic A. baumannii infection that mirrors that of wild-type (WT) mice, and exogenous IL-10 administration to WT mice enhances survival in this model. These findings demonstrate the role for RAGE-dependent IL-10 suppression as a key modulator of mortality from Gram-negative sepsis.

Gender Difference in Bacteria Endotoxin-Induced Inflammatory and Anorexic Responses

Inflammation-related anorexic response has been observed in systemic diseases as well as in localized infection and is an important issue in patient care. We tested the hypothesis that upon the same endotoxin exposure, males have more severe inflammatory responses and thus suffer from more negative effect on appetite. Ten-week old male and female mice were compared in their plasma levels of pro-inflammatory cytokines after a body weight-based i.p. injection of bacterial endotoxin lipopolysaccharide. Male mice consistently showed significantly higher levels of IL6 and TNFα than female mice. The difference was observed starting at 3 hours after the systemic endotoxin exposure. It was independent of the level of endotoxin dosage and of the genotype of the anti-inflammatory cytokine, IL10. Interestingly, endotoxin-injected male mice also had significantly higher plasma IL10 levels compared to the female mice. Pre-puberty young mice showed no gender differences in the plasma levels of IL6, TNFα and IL10. Their cytokine levels were mostly between that of the adult males and females. Consistent with the higher inflammatory response in male mice, the endotoxin exposure also led to significantly more appetite loss in male mice at a range of doses in two strains of mice. Saline injection in the absence of endotoxin affected neither the cytokine levels nor the appetite. Although a direct mechanistic link between inflammation parameters and appetite was not addressed here, the results support that male gender could be a risk factor for higher pro-inflammatory cytokines and anorexic response after the endotoxin exposure.

Modulating macrophage function with IgG immune complexes

Macrophages respond to bacterial products by releasing a large array of inflammatory mediators. We demonstrate that, in the presence of IgG immune complexes, macrophages produce high levels of IL-10 and virtually no IL-12, when they are exposed to bacterial products. The production of IL-10 by these cells can dampen innate inflammatory responses to microbial products, such as LPS. This alteration in macrophage cytokine production can also influence an adaptive immune response, preferentially inducing Th2-type immunity. Thus, immune complexes change the physiology of activated macrophages, converting them to anti-inflammatory cells that induce Th2-like immune responses. We have termed these cells type II activated macrophages.

Augmentation of anti-cytokine immunotherapy by combining neutralizing monoclonal antibodies to interferon-γ and the interferon-γ receptor: protection in endotoxin shock

We have employed neutralizing monoclonal antibodies to mouse interferon-γ (IFNγ) and to the receptor for mouse IFNy in studies designed to assess the protective efficacy of each of these monoclonals, administered either separately or in combination, in endotoxin-induced lethality. While pretreatment with either antibody alone, at doses of 200 μg per mouse, provided limited protection (70-50% lethality) in comparison to non-neutralizing antibody controls (100% lethality), the two monoclonal antibodies administered together provided a substantially greater level of protection (17% lethality). Although administration of 100 μg per mouse of either monoclonal alone was not protective (more than 65% lethality), a combination of both antibodies at this dose provided significant protection (19% lethality). In addition, administration of both antibodies 30 min post-endotoxin challenge also demonstrated significant protection in comparison to single antibody immunotherapy. In vitro studies using mouse peritoneal macrophages stimulated with LPS and IFNy have established confirmatory data for a synergistic effect of neutralizing antibody to IFNy and the IFNγ receptor in inhibiting macrophage activation as assessed by production of nitric oxide. These results provide a strong rationale for dual targeting of ligand and receptor in single cytokine immunotherapy.