Ligand Activation of the Aryl Hydrocarbon Receptor Upregulates Epidermal Uridine Diphosphate Glucose Ceramide Glucosyltransferase and Glucosylceramides

Ligand activation of the aryl hydrocarbon receptor (AHR) accelerates keratinocyte differentiation and the formation of the epidermal permeability barrier. Several classes of lipids, including ceramides, are critical to the epidermal permeability barrier. In normal human epidermal keratinocytes, the AHR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin, increased RNA levels of ceramide metabolism and transport genes: uridine diphosphate glucose ceramide glucosyltransferase (UGCG), ABCA12, GBA1, and SMPD1. Levels of abundant skin ceramides were also increased by 2,3,7,8-tetrachlorodibenzo-p-dioxin. These included the metabolites synthesized by UGCG, glucosylceramides, and acyl glucosylceramides. Chromatin immunoprecipitation-sequence analysis and luciferase reporter assays identified UGCG as a direct AHR target. The AHR antagonist, GNF351, inhibited the 2,3,7,8-tetrachlorodibenzo-p-dioxin-mediated RNA and transcriptional increases. Tapinarof, an AHR ligand approved for the treatment of psoriasis, increased UGCG RNA, protein, and its lipid metabolites hexosylceramides as well as increased the RNA expression of ABCA12, GBA1, and SMPD1. In Ahr-null mice, Ugcg RNA and hexosylceramides were lower than those in the wild type. These results indicate that the AHR regulates the expression of UGCG, a ceramide-metabolizing enzyme required for ceramide trafficking, keratinocyte differentiation, and epidermal permeability barrier formation.

The fetal response to maternal inflammation is dependent upon maternal IL-6 in a murine model

BACKGROUND

The induction of maternal inflammation in mice leads to fetal injury that is believed to be IL-6 dependent. The fetal inflammatory response, defined by elevated fetal or amniotic fluid IL-6, has been described as a potential mechanism for subsequent fetal injury. The role of maternal IL-6 production and signaling in the fetal IL-6 response is currently unclear.

METHODS

Genetic and anti-IL-6 antibody strategies were used to systematically block the maternal IL-6 response during inflammation. Chorioamnionitis was induced using intraperitoneal injection of lipopolysaccharide (LPS) at mid gestation (E14.5) and late gestation (E18.5). This model was used in pregnant C57Bl/6 dams, IL6^-/- dams, C57Bl/6 dams treated with anti-IL-6 (blocks both classical and trans-signaling) or anti-gp130 antibodies (blocks trans-signaling only) and IL6^+/- dams. Six hours following LPS injection, maternal serum, placental tissue, amniotic fluid and fetal tissue or serum were collected. A bead-based multiplex assay was used to evaluate levels of IL-6, KC, IL-1β, TNF, IL-10, IL-22, IFN-γ, IL-13 and IL-17A.

RESULTS

Chorioamnionitis in C57Bl/6 dams was characterized by elevated maternal serum levels of IL-6, KC and IL-22 with litter loss during mid gestation. The fetal response to maternal inflammation in C57Bl/6 mice was primarily characterized by elevated levels of IL-6, KC and IL-22 in the placenta, amniotic fluid and fetus during both mid and late gestation. A global IL-6 knockout (IL6^-/-) eradicated the maternal, placental, amniotic fluid and fetal IL-6 response to LPS during mid and late gestation and improved litter survival, while minimally influencing the KC or IL-22 responses. Blocking maternal classical IL-6 signaling in C57Bl/6 dams at the time of LPS exposure diminished the maternal, placental, amniotic fluid and fetal IL-6 response during mid and late gestation, while blocking maternal IL-6 trans-signaling only affected fetal IL-6 expression. To evaluate whether maternal IL-6 was crossing the placenta and reaching the fetus, IL-6^+/- dams were utilized in the chorioamnionitis model. IL-6^+/- dams mounted a systemic inflammatory response following injection with LPS, characterized by elevated IL-6, KC and IL-22. IL-6^-/- pups born to IL6^+/- dams had decreased amniotic fluid levels of IL-6 and undetectable levels of fetal IL-6 compared to IL-6^+/+ littermate controls.

CONCLUSION

The fetal response to systemic maternal inflammation is dependent upon maternal IL-6 signaling, but maternal IL-6 is not crossing the placenta and reaching the fetus at detectable levels.

The Potential Importance of CXCL1 in the Physiological State and in Noncancer Diseases of the Cardiovascular System, Respiratory System and Skin

In this paper, we present a literature review of the role of CXC motif chemokine ligand 1 (CXCL1) in physiology, and in selected major non-cancer diseases of the cardiovascular system, respiratory system and skin. CXCL1, a cytokine belonging to the CXC sub-family of chemokines with CXC motif chemokine receptor 2 (CXCR2) as its main receptor, causes the migration and infiltration of neutrophils to the sites of high expression. This implicates CXCL1 in many adverse conditions associated with inflammation and the accumulation of neutrophils. The aim of this study was to describe the significance of CXCL1 in selected diseases of the cardiovascular system (atherosclerosis, atrial fibrillation, chronic ischemic heart disease, hypertension, sepsis including sepsis-associated encephalopathy and sepsis-associated acute kidney injury), the respiratory system (asthma, chronic obstructive pulmonary disease (COPD), chronic rhinosinusitis, coronavirus disease 2019 (COVID-19), influenza, lung transplantation and ischemic-reperfusion injury and tuberculosis) and the skin (wound healing, psoriasis, sunburn and xeroderma pigmentosum). Additionally, the significance of CXCL1 is described in vascular physiology, such as the effects of CXCL1 on angiogenesis and arteriogenesis.

The Importance of CXCL1 in Physiology and Noncancerous Diseases of Bone, Bone Marrow, Muscle and the Nervous System

This review describes the role of CXCL1, a chemokine crucial in inflammation as a chemoattractant for neutrophils, in physiology and in selected major non-cancer diseases. Due to the vast amount of available information, we focus on the role CXCL1 plays in the physiology of bones, bone marrow, muscle and the nervous system. For this reason, we describe its effects on hematopoietic stem cells, myoblasts, oligodendrocyte progenitors and osteoclast precursors. We also present the involvement of CXCL1 in diseases of selected tissues and organs including Alzheimer’s disease, epilepsy, herpes simplex virus type 1 (HSV-1) encephalitis, ischemic stroke, major depression, multiple sclerosis, neuromyelitis optica, neuropathic pain, osteoporosis, prion diseases, rheumatoid arthritis, tick-borne encephalitis (TBE), traumatic spinal cord injury and West Nile fever.

Differences in health care resource utilization and costs for keratinocyte carcinoma among racioethnic groups: A population-based study

BACKGROUND

As the United States becomes more diverse, determining differences in health care utilization and costs in the management of skin cancers is fundamental to decision-making in health care resource allocation and improving care for underserved populations.

OBJECTIVE

To compare health care use and costs among non-Hispanic White, Hispanic White, and non-Hispanic Black patients with keratinocyte carcinoma.

METHODS

A nationwide cross-sectional study was performed using Medical Expenditure Panel Survey data from 1996 to 2015.

RESULTS

Among 54,503,447 patients with keratinocyte carcinoma (weighted) over a 20-year period, 53,134,351 (97%) were non-Hispanic White; 836,030 (1.5%) were Hispanic White; and 170,755 (0.3%) were non-Hispanic Black. Compared to non-Hispanic White patients, Hispanic White patients had significantly more ambulatory visits per person per year (5.4 vs 3.5, P = .003). Compared to non-Hispanic White patients, non-Hispanic Black patients had significantly more ambulatory visits (13.1 vs 3.5, P = .027) and emergency department visits (2.3 vs 1.1, P < .001), and incurred significantly higher ambulatory costs ($5089 vs $1131, P = .05), medication costs ($523 vs $221, P = .022), and total costs per person per year ($13,430 vs $1290, P = .032).

LIMITATIONS

Data for squamous cell carcinomas and basal cell carcinomas are combined.

CONCLUSIONS

Keratinocyte carcinoma was more costly to treat and required more health care resources in non-Hispanic Black and Hispanic White patients than in non-Hispanic White patients.

Role of Innate Inflammation in the Regulation of Tissue Remodeling during Tooth Eruption

Tooth eruption is characterized by a coordinated complex cascade of cellular and molecular events that promote tooth movement through the eruptive pathway. During tooth eruption, the stratum intermedium structurally changes to the papillary layer with tooth organ development. We previously reported intercellular adhesion molecule-1 (ICAM-1) expression on the papillary layer, which is the origin of the ICAM-1-positive junctional epithelium. ICAM-1 expression is induced by proinflammatory cytokines, including interleukin-1 and tumor necrosis factor. Inflammatory reactions induce tissue degradation. Therefore, this study aimed to examine whether inflammatory reactions are involved in tooth eruption. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed sequential expression of hypoxia-induced factor-1α, interleukin-1β, and chemotactic factors, including keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2 (MIP-2), during tooth eruption. Consistent with the RT-PCR results, immunohistochemical analysis revealed KC and MIP-2 expression in the papillary layer cells of the enamel organ from the ameloblast maturation stage. Moreover, there was massive macrophage and neutrophil infiltration in the connective tissue between the tooth organ and oral epithelium during tooth eruption. These findings suggest that inflammatory reactions might be involved in the degradation of tissue overlying the tooth organ. Further, these reactions might be induced by hypoxia in the tissue overlying the tooth organ, which results from decreased capillaries in the tissue. Our findings indicate that bacterial infections are not associated with the eruption process. Therefore, tooth eruption might be regulated by innate inflammatory mechanisms.

Antiviral and Immunomodulatory Activity of Silver Nanoparticles in Experimental RSV Infection

Respiratory syncytial virus (RSV) is an important etiological agent of respiratory infection in children for which no specific treatment option is available. The RSV virion contains two surface glycoproteins (F and G) that are vital for the initial phases of infection, making them critical targets for RSV therapeutics. Recent studies have identified the broad-spectrum antiviral properties of silver nanoparticles (AgNPs) against respiratory pathogens, such as adenovirus, parainfluenza, and influenza. AgNPs achieve this by attaching to viral glycoproteins, blocking entry into the host cell. The objective of this study was to evaluate the antiviral and immunomodulatory effects of AgNPs in RSV infection. Herein we demonstrate AgNP-mediated reduction in RSV replication, both in epithelial cell lines and in experimentally infected BALB/c mice. Marked reduction in pro-inflammatory cytokines (i.e., IL-1α, IL-6, TNF-α) and pro-inflammatory chemokines (i.e., CCL2, CCL3, CCL5) was also observed. Conversely, CXCL1, G-CSF, and GM-CSF were increased in RSV-infected mice treated with AgNPs, consistent with an increase of neutrophil recruitment and activation in the lung tissue. Following experimental antibody-dependent depletion of neutrophils, the antiviral effect of AgNPs in mice treated was ablated. To our knowledge, this is the first in vivo report demonstrating antiviral activity of AgNPs during RSV infection.

Ghrelin therapy mitigates bone marrow injury and splenocytopenia by sustaining circulating G-CSF and KC increases after irradiation combined with wound

Background

Radiation injury combined wound (CI) enhances acute radiation syndrome and subsequently mortality as compared to radiation injury alone (RI). We previously reported that ghrelin (a 28-amino-acid-peptide secreted from the stomach) treatment significantly increased a 30-day survival, mitigated hematopoietic death, circulating white blood cell (WBC) depletion and splenocytopenia and accelerated skin-wound healing on day 30 after CI. Herein, we aimed to study the ghrelin efficacy at early time points after CI.

Methods

B6D2F1/J female mice were exposed to ⁶⁰Co-γ-photon radiation at 9.5 Gy (LD_50/30) followed by a 15% total-body-surface-area skin wound. Several endpoints were measured at 4-5 h, days 1, 3, 7 and 15.

Results

Histological analysis of sternums on day 15 showed that CI induced more adipocytes and less megakaryocytes than RI. Bone marrow cell counts from femurs also indicated CI resulted in lower bone marrow cell counts on days 1, 7 and 15 than RI. Ghrelin treatment mitigated these CI-induced adverse effects. RI and CI decreased WBCs within 4-5 h and continued to decrease to day 15. Ghrelin treatment mitigated decreases in CI mice, mainly from all types of WBCs, but not RBCs, hemoglobin levels and hematocrit values. Ghrelin mitigated the CI-induced thrombocytopenia and splenocytopenia. CI increased granulocyte-colony stimulating factor (G-CSF) and keratinocyte chemoattractant (KC) in blood and bone marrow. Ghrelin therapy was able to enhance and sustain the increases in serum on day 15, probably contributed by spleen and ileum, suggesting the correlation between G-CSF and KC increases and the neutropenia mitigation. Activated caspase-3 levels in bone marrow cells were significantly mitigated by ghrelin therapy on days 3 and 15.

Conclusions

Our novel results are the first to suggest that ghrelin therapy effectively decreases hematopoietic death and splenocytopenia by sustaining circulating G-CSF and KC increases after CI. These results demonstrate efficacy of ghrelin as a radio-mitigator/therapy agent for CI.

NLRP3 inflammasome induced liver graft injury through activation of telomere-independent RAP1/KC axis

Acute-phase inflammation plays a critical role in liver graft injury. Inflammasomes, multi-molecular complexes in the cytoplasm, are responsible for initiating inflammation. Here, we aimed to explore the role of inflammasomes in liver graft injury and further to investigate the regulatory mechanism. In a clinical liver transplant cohort, we found that intragraft expression of nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasomes was significantly up-regulated post-transplantation. Importantly, overexpression of NLRP3 was strongly associated with poor liver function characterized by high levels of ALT, AST, and urea, as well as neutrophil infiltration after transplantation. The significant correlation between NLRP3 and IL-1β mRNA levels led us to focus on one of the associated upstream regulators, telomere-independent repressor activator protein 1 (RAP1), which was further proved to be co-localized with NLRP3 in neutrophils. In the liver of a mouse model (hepatic ischaemia/reperfusion and hepatectomy model) and isolated neutrophils from RAP1^-/- mice, the expression levels of NLRP3 and keratinocyte chemoattractant (KC) were significantly down-regulated in contrast to those in wild types. The levels of ALT and AST, as well as the neutrophil infiltration, were also decreased by RAP1 deficiency. In our clinical validation, intragraft KC expression was associated with NLRP3 and co-localized with RAP1 in neutrophils. Furthermore, NLRP3 inflammasomes were up-regulated by recombinant KC in the isolated neutrophils and liver of the mouse model. Our data demonstrated that NLRP3 inflammasomes, activated by the RAP1/KC axis, played a critical role in initiating inflammation during the early stage of liver graft injury. Targeting RAP1/KC/NLRP3 inflammasomes may offer a new therapeutic strategy against liver graft injury. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Protective Role of Proton-Sensing TDAG8 in Lipopolysaccharide-Induced Acute Lung Injury

Acute lung injury is characterized by the infiltration of neutrophils into lungs and the subsequent impairment of lung function. Here we explored the role of TDAG8 in lung injury induced by lipopolysaccharide (LPS) administrated intratracheally. In this model, cytokines and chemokines released from resident macrophages are shown to cause neutrophilic inflammation in the lungs. We found that LPS treatment increased TDAG8 expression in the lungs and confirmed its expression in resident macrophages in bronchoalveolar lavage (BAL) fluids. LPS administration remarkably increased neutrophil accumulation without appreciable change in the resident macrophages, which was associated with increased penetration of blood proteins into BAL fluids, interstitial accumulation of inflammatory cells, and damage of the alveolar architecture. The LPS-induced neutrophil accumulation and the associated lung damage were enhanced in TDAG8-deficient mice as compared with those in wild-type mice. LPS also increased several mRNA and protein expressions of inflammatory cytokines and chemokines in the lungs or BAL fluids. Among these inflammatory mediators, mRNA and protein expression of KC (also known as CXCL1), a chemokine of neutrophils, were significantly enhanced by TDAG8 deficiency. We conclude that TDAG8 is a negative regulator for lung neutrophilic inflammation and injury, in part, through the inhibition of chemokine production.

Interleukin 8/KC enhances G-CSF induced hematopoietic stem/progenitor cell mobilization in Fancg deficient mice

BACKGROUND

Fanconi anemia (FA) is a heterogeneous genetic disorder characterized by a progressive bone marrow aplasia, chromosomal instability, and acquisition of malignancies. Successful hematopoietic cell transplantation (HCT) for FA patients is challenging due to hypersensitivity to DNA alkylating agents and irradiation of FA patients. Early mobilization of autologous stem cells from the bone marrow has been thought to be ideal prior to the onset of bone marrow failure, which often occurs during childhood. However, the markedly decreased response of FA hematopoietic stem cells to granulocyte colony-stimulating factor (G-CSF) is circumventive of this autologous HCT approach. To-date, the mechanism for defective stem cell mobilization in G-CSF treated FA patients remains unclear.

METHODS

Fancg heterozygous (Fancg (+/-)) mice utilized in these studies. Student's t-test and one-way ANOVA were used to evaluate statistical differences between WT and Fancg (-/-) cells. Statistical significance was defined as P values less than 0.05.

RESULTS

Fancg deficient (Fancg (-/-)) mesenchymal stem/progenitor cells (MSPCs) produce significant lower levels of KC, an interleukin-8 (IL-8) related chemoattractant protein in rodents, as compared to wild type cells. Combinatorial administration of KC and G-CSF significantly increased the mobilization of hematopoietic stem/progenitor cells (HSPCs) in Fancg (-/-) mice.

CONCLUSIONS

In summary, our results suggest that KC/IL-8 could be proved useful in the synergistic mobilization of FA HSPCs in combination with G-CSF.

GPR120 on Kupffer cells mediates hepatoprotective effects of ω3-fatty acids

BACKGROUND & AIMS

Many of the beneficial effects of ω3-fatty acids (ω3FAs) are being attributed to their anti-inflammatory properties. In animal models, ω3FAs also protect from hepatic ischemia reperfusion injury (IRI), a significant cause of complications following liver surgery. Omegaven®, a clinical ω3FA-formulation, might counteract the exaggerated inflammatory response underlying IRI, but the according mechanisms are unresearched. Recently, GPR120 has been identified as a first receptor for ω3FAs, mediating their anti-inflammatory effects. Here, we sought to investigate whether Omegaven® protects from hepatic IRI through GPR120.

METHODS

Using a mouse model of liver IRI, we compared the effects of a GPR120 agonist with those of Omegaven®.

RESULTS

GPR120 in liver was located to Kupffer cells (KCs). Agonist and Omegaven® provided similar protection from IRI, which was abolished by clodronate-depletion of KCs or by pretreatment with an αGpr120-siRNA. In vitro and in vivo, both agents dampened the NFκB/JNK-mediated inflammatory response. Dampening was associated with an M1>M2 macrophage polarization shift as assessed by marker expression. In αGpr120-siRNA-pretreated mice with or without ischemia, Omegaven® was no more able to promote M2 marker expression, indicating its anti-inflammatory properties are dependent on GPR120 in liver.

CONCLUSIONS

These findings establish KC-GPR120 as a key mediator of Omegaven® effects and suggest GPR120 as a therapeutic target to mitigate inflammatory stress in liver.

C5aR and C5L2 act in concert to balance immunometabolism in adipose tissue

Recent studies suggested that the immunometabolic receptors; C5aR and C5L2, constitutively self-associate into homo-/heterodimers and that acylation stimulating protein (ASP/C3adesArg) or C5a treatment of adipocytes increased their colocalization. The present study evaluates the C5aR contribution in adipocytes to the metabolic and immune responses elicited by ligand stimulation. The effects of C5a, ASP, and insulin on cytokine production, triglyceride synthesis (TGS), and key signaling pathways were evaluated in isolated primary adipocytes and cultured 3T3-L1 differentiated adipocytes. In addition, mRNA expression of IRS1 and PGC1α was compared in adipose tissue samples from WT vs. C5aRKO mice. Both C5a and ASP directly increased MCP-1 (238±4%; P<0.001, and 377±2% vs. basal 100%; P<0.001, respectively) and KC (413±11%; P<0.001, and 529±16%; P<0.001 vs. basal 100%, respectively) secretion, TGS (131±1%; P<0.001, and 152±6%; P<0.001, vs. basal 100% respectively), and Akt/NFκB phosphorylation pathways in adipocytes. However, in C5aRKO adipocytes, C5a effects were disrupted, while stimulatory effects of ASP were mostly maintained. Addition of C5a completely blocked ASP signaling and activity in both C5aRKO and WT adipocytes as well as 3T3-L1 adipocytes. Furthermore, C5aRKO adipocytes revealed impaired insulin stimulation of cytokine production, with partial impairment of signaling and TGS stimulation, consistent with decreased IRS1 and PGC1α mRNA expression in adipose tissue. These observations indicate the importance of C5aR in adipose tissue metabolism and immunity, which may be regulated through heterodimerization with C5L2.

Dimethylarginine dimethylaminohydrolase (DDAH) overexpression attenuates agricultural organic dust extract-induced inflammation

Modern, industrialized farming practices have lead to working conditions that include high levels of airborne dust. Agricultural workers inhale these complex organic dusts on a daily basis, leading to airway inflammation and higher risk for developing chronic obstructive pulmonary disease. The mechanisms regulating the organic dust-induced airway inflammatory response are not well-defined. We investigated whether overexpression of dimethylarginine dimethylaminohydrolase (DDAH) would lead to diminished pulmonary inflammation in an animal model of organic dust extract exposure. We instilled wild-type (WT) and DDAH overexpressing mice with an aqueous organic dust extract (ODE) collected from a swine confinement building. We found that inflammatory indices such as neutrophil influx and inflammatory cytokine production was lower in the DDAH overexpressing mice compared to WT after organic dust extract (ODE) instillation. We went on to determine how DDAH was mediating the decrease in inflammation induced by ODE. PKCα and PKCε play an essential role in the ODE inflammatory response. In a model of lung slices from WT and DDAH overexpressing mice, we demonstrated an increase in PKCα and PKCε in the WT mice exposed to ODE. This increase was diminished in the DDAH overexpressing mice exposed to ODE. We also tested an important component of the ODE, peptidoglycan (PGN). We noted a similar decrease in neutrophils and inflammatory cytokines in the DDAH overexpressing animals instilled with PGN compared to WT. In conclusion, our studies found a role for DDAH in regulating the ODE-triggered activation of epithelial PKCα and PKCε, a previously unrecognized mechanism of action. This ultimately results in diminished pulmonary inflammation.

7α-hydroxylation of dehydroepiandrosterone does not interfere with the activation of glucocorticoids by 11β-hydroxysteroid dehydrogenase in E(t)C cerebellar neurons

The neuroprotective action of dehydroepiandrosterone (DHEA) in the absence of a known specific receptor has been attributed to its metabolism by different cell types in the brain to various steroids, with a preference to its 7-hydroxylated products. The E(t)C cerebellar granule cell line converts DHEA almost exclusively to 7α-hydroxy-DHEA (7α-OH-DHEA). It has been postulated that DHEA's 7-OH and 7-oxo metabolites can decrease glucocorticoid levels by an interactive mechanism involving 11β-hydroxysteroid dehydrogenase (11β-HSD). In order to study the relationship of 7-hydroxylation of DHEA and glucocorticoid metabolism in intact brain cells, we examined whether E(t)C cerebellar neurons, which are avid producers of 7α-OH-DHEA, could also metabolize glucocorticoids. We report that E(t)C neuronal cells exhibit 11β-HSD1 reductase activity, and are able to convert 11-dehydrocorticosterone into corticosterone, whereas they do not demonstrate 11β-HSD2 dehydrogenase activity. Consequently, E(t)C cells incubated with DHEA did not yield 7-oxo- or 7β-OH-DHEA. Our findings are supported by the reductive environment of E(t)C cells through expression of hexose-6-phosphate dehydrogenase (H6PDH), which fosters 11β-HSD1 reductase activity. To further explore the role of 7α-OH-DHEA in E(t)C neuronal cells, we examined the effect of preventing its formation using the CYP450 inhibitor ketoconazole. Treatment of the cells with this drug decreased the yield of 7α-OH-DHEA by about 75% without the formation of alternate DHEA metabolites, and had minimal effects on glucocorticoid conversion. Likewise, elevated levels of corticosterone, the product of 11β-HSD1, had no effect on the metabolic profile of DHEA. This study shows that in a single population of whole-cells, with a highly reductive environment, 7α-OH-DHEA is unable to block the reducing activity of 11β-HSD1, and that 7-hydroxylation of DHEA does not interfere with the activation of glucocorticoids. Our investigation on the metabolism of DHEA in E(t)C neuronal cells suggest that other alternate mechanisms must be at play to explain the in vivo anti-glucocorticoid properties of DHEA and its 7-OH-metabolites.

Regulation of accumulation and function of myeloid derived suppressor cells in different murine models of hepatocellular carcinoma

BACKGROUND & AIMS

Myeloid derived suppressor cells (MDSC) are immature myeloid cells with immunosuppressive activity. They accumulate in tumor-bearing mice and humans with different types of cancer, including hepatocellular carcinoma (HCC). The aim of this study was to examine the biology of MDSC in murine HCC models and to identify a model, which mimics the human disease.

METHODS

The comparative analysis of MDSC was performed in mice, bearing transplantable, diethylnitrosoamine (DEN)-induced and MYC-expressing HCC at different ages.

RESULTS

An accumulation of MDSC was found in mice with HCC irrespective of the model tested. Transplantable tumors rapidly induced systemic recruitment of MDSC, in contrast to slow-growing DEN-induced or MYC-expressing HCC, where MDSC numbers only increased intra-hepatically in mice with advanced tumors. MDSC derived from mice with subcutaneous tumors were more suppressive than those from mice with DEN-induced HCC. Enhanced expression of genes associated with MDSC generation (GM-CSF, VEGF, IL6, IL1β) and migration (MCP-1, KC, S100A8, S100A9) was observed in mice with subcutaneous tumors. In contrast, only KC levels increased in mice with DEN-induced HCC. Both KC and GM-CSF overexpression or anti-KC and anti-GM-CSF treatment controlled MDSC frequency in mice with HCC. Finally, the frequency of MDSC decreased upon successful anti-tumor treatment with sorafenib.

CONCLUSIONS

Our data indicate that MDSC accumulation is a late event during hepatocarcinogenesis and differs significantly depending on the tumor model studied.

Hepatic ischemia and reperfusion injury: effects on the liver sinusoidal milieu

Ischemia-reperfusion injury is an important cause of liver damage occurring during surgical procedures including hepatic resection and liver transplantation, and represents the main underlying cause of graft dysfunction post-transplantation. Cellular and biochemical processes occurring during hepatic ischemia-reperfusion are diverse and complex, and include the deregulation of the healthy phenotype of all liver cellular components. Nevertheless, a significant part of these processes are still unknown or unclear. The present review aims at summarizing the current knowledge in liver ischemia-reperfusion, but specifically focusing on liver cell phenotype and paracrine interaction deregulations. Moreover, the most updated therapeutic strategies including pharmacological, genetic and surgical interventions, as well as some of the scientific controversies in the field will be described. Finally, the importance of considering the subclinical situation of liver grafts when translating basic knowledge to the bedside is discussed.

Endoplasmic reticulum stress influences bronchial asthma pathogenesis by modulating nuclear factor κB activation

BACKGROUND

Despite many studies on endoplasmic reticulum (ER) stress in patients with various inflammatory diseases, there is scarce information on ER stress in patients with bronchial asthma.

OBJECTIVE

In this study we aimed to elucidate the role of ER stress in the pathogenesis of bronchial asthma.

METHODS

Using mice sensitized with ovalbumin (OVA) and LPS and challenged with OVA (OVA(LPS)-OVA mice), as well as mice sensitized and challenged with OVA (OVA-OVA mice), we investigated whether ER stress is involved in the pathogenesis of bronchial asthma. Moreover, we also determined the levels of ER stress markers in blood and bronchoalveolar lavage fluid from asthmatic patients.

RESULTS

The OVA(LPS)-OVA mice showed that the expression of ER stress markers and the protein levels of unfolded protein response-related markers in lung tissue were significantly increased after OVA challenge. Moreover, we found that ER stress markers in PBMCs and bronchoalveolar lavage fluid from human asthmatic patients were dramatically increased compared with those from healthy control subjects. In OVA(LPS)-OVA mice 4-phenylbutyric acid (4-PBA), a chemical chaperone, significantly reduced the increases in ER stress, nuclear translocation of nuclear factor κB, inflammatory cytokine levels, dendritic cell infiltration, Toll-like receptor 4 expression, airway inflammation, and bronchial hyperresponsiveness, whereas it further enhanced the increase in IL-10 levels. Additionally, the established asthmatic features of OVA-OVA mice were substantially attenuated by 4-PBA administered after completion of OVA challenge.

CONCLUSION

These results indicate that ER stress might be implicated in the pathogenesis of bronchial asthma at least in part through modulation of nuclear factor κB activation.

Neurotensin-loaded collagen dressings reduce inflammation and improve wound healing in diabetic mice

Impaired wound healing is an important clinical problem in diabetes mellitus and results in failure to completely heal diabetic foot ulcers (DFUs), which may lead to lower extremity amputations. In the present study, collagen based dressings were prepared to be applied as support for the delivery of neurotensin (NT), a neuropeptide that acts as an inflammatory modulator in wound healing. The performance of NT alone and NT-loaded collagen matrices to treat wounds in streptozotocin (STZ) diabetic induced mice was evaluated. Results showed that the prepared dressings were not-cytotoxic up to 72h after contact with macrophages (Raw 264.7) and human keratinocyte (HaCaT) cell lines. Moreover, those cells were shown to adhere to the collagen matrices without noticeable change in their morphology. NT-loaded collagen dressings induced faster healing (17% wound area reduction) in the early phases of wound healing in diabetic wounded mice. In addition, they also significantly reduced inflammatory cytokine expression namely, TNF-α (p<0.01) and IL-1β (p<0.01) and decreased the inflammatory infiltrate at day 3 post-wounding (inflammatory phase). After complete healing, metalloproteinase 9 (MMP-9) is reduced in diabetic skin (p<0.05) which significantly increased fibroblast migration and collagen (collagen type I, alpha 2 (COL1A2) and collagen type III, alpha 1 (COL3A1)) expression and deposition. These results suggest that collagen-based dressings can be an effective support for NT release into diabetic wound enhancing the healing process. Nevertheless, a more prominent scar is observed in diabetic wounds treated with collagen when compared to the treatment with NT alone.

Effects of Ureaplasma parvum lipoprotein multiple-banded antigen on pregnancy outcome in mice

Ureaplasma spp. are members of the family Mycoplasmataceae and have been considered to be associated with chorioamnionitis and preterm delivery. However, it is unclear whether Ureaplasma spp. have virulence factors related to these manifestations. The purpose of the present study was to determine whether the immunogenic protein multiple-banded antigen (MBA) from Ureaplasma parvum is a virulence factor for preterm delivery. We partially purified MBA from a type strain and clinical isolates of U. parvum, and also synthesized a diacylated lipopeptide derived from U. parvum, UPM-1. Using luciferase assays, both MBA-rich fraction MRF and UPM-1 activated the NF-κB pathway via TLR2. UPM-1 upregulated IL-1β, IL-6, IL-12p35, TNF-α, MIP2, LIX, and iNOS in mouse peritoneal macrophage. MRF or UPM-1 was injected into uteri on day 15 of gestation on pregnant C3H/HeN mice. The intrauterine MRF injection group had a significantly higher incidence of intrauterine fetal death (IUFD; 38.5%) than the control group (14.0%). Interestingly, intrauterine injection of UPM-1 caused preterm deliveries at high concentration (80.0%). In contrast, a low concentration of UPM-1 induced a significantly higher rate of fetal deaths (55.2%) than the control group (14.0%). The placentas of the UPM-1 injection group showed neutrophil infiltration and increased iNOS protein expression. Our data indicate that MBA from the clinical isolate of U. parvum is a potential virulence factor for IUFD and preterm delivery in mice and that the N-terminal diacylated lipopeptide is essential for the initiation of inflammation.

Local inflammatory reaction induced by Scolopendra viridicornis centipede venom in mice

Centipede envenomation is generally mild, and human victims usually manifest burning pain, erythema and edema. Despite the abundance and ubiquity of these animals, centipede venom has been poorly characterized in literature. For this reason, the aim of this work was to investigate local inflammatory features induced by Scolopendra viridicornis centipede envenomation in mice, evaluating edema formation, leukocyte infiltration, production of inflammatory mediators, and also performing histological analysis. The highest edematogenic activity induced by the venom, determined by plethysmometry, was noticed 0.5 h after injection in mice footpad. At 24 h, edema was still detected in animals that received 15 and 60 μg of venom, and at 48 h, only in animals injected with 60 μg of venom. In relation to leukocyte count, S. viridicornis venom induced cell recruitment, mainly neutrophils and monocytes/macrophages, in all doses and time periods analyzed in comparison with PBS-injected mice. An increase in lymphocytes was detected especially between 1 and 24 h at 60 μg dose. Besides, eosinophil recruitment was observed mainly for 15 and 60 μg doses in early time periods. Edema formation and cell recruitment were also confirmed by histological analysis. Moreover, S. viridicornis venom stimulated the release of IL-6, MCP-1, KC, and IL-1β. Conversely, S. viridicornis venom did not induce the release of detectable levels of TNF-α. We demonstrated that the edematogenic activity induced by S. viridicornis venom was of rapid onset, and the venom stimulated secretion of pro-inflammatory mediators which contribute to the inflammatory reaction induced by S. viridicornis venom in an experimental model.

Acute metabolic amplification of insulin secretion in mouse islets is mediated by mitochondrial export of metabolites, but not by mitochondrial energy generation

OBJECTIVE

The β-cell metabolism of glucose and of some other fuels (e.g. α-ketoisocaproate) generates signals triggering and acutely amplifying insulin secretion. As the pathway coupling metabolism with amplification is largely unknown, we aimed to narrow down the putative amplifying signals.

MATERIALS/METHODS

An experimental design was used which previously prevented glucose-induced, but not α-ketoisocaproate-induced insulin secretion. Isolated mouse islets were pretreated for one hour with medium devoid of fuels and containing the sulfonylurea glipizide in high concentration which closed all ATP-sensitive K(+) channels. This concentration was also applied during the subsequent examination of fuel-induced effects. In perifused or incubated islets, insulin secretion and metabolic parameters were measured.

RESULTS

The pretreatment decreased the islet ATP/ADP ratio. Whereas glucose and α-ketoisovalerate were ineffective or weakly effective, respectively, when tested separately, their combination strongly enhanced the insulin secretion. Compared with glucose, the strong amplifier α-ketoisocaproate caused less increase in NAD(P)H-fluorescence and less mitochondrial hyperpolarization. Compared with α-ketoisovalerate, α-ketoisocaproate caused greater increase in NAD(P)H-fluorescence and greater mitochondrial hyperpolarization. Neither α-ketoacid anion enhanced the islet ATP/ADP ratio during onset of the insulin secretion. α-Ketoisocaproate induced a higher pyruvate content than glucose, slowly elevated the citrate content which was not changed by glucose and generated a much higher acetoacetate content than other fuels. α-Ketoisovalerate alone or in combination with glucose did not increase the citrate content.

CONCLUSIONS

In β-cells, mitochondrial energy generation does not mediate acute metabolic amplification, but mitochondrial production of acetyl-CoA and supplemental acetoacetate supplies cytosolic metabolites which induce the generation of specific amplifying signals.

Functional relevance of the cannabinoid receptor 2 - heme oxygenase pathway: a novel target for the attenuation of portal hypertension

AIMS

In liver cirrhosis, inflammation triggers portal hypertension. Kupffer cells (KC) produce vasoconstrictors upon activation by bacterial constituents. Here, we hypothesize that the anti-inflammatory action of the cannabinoid receptor 2 (CB2) agonists JWH-133 and GP 1a attenuate portal hypertension.

MAIN METHODS

In vivo measurements of portal pressures and non-recirculating liver perfusions were performed in rats 4weeks after bile duct ligation (BDL). Zymosan (150μg/ml, isolated liver perfusion) or LPS (4mg/kgb.w., in vivo) was infused to activate the KC in the absence or presence of JWH-133 (10mg/kgb.w.), GP 1a (2.5mg/kgb.w.) or ZnPP IX (1μM). Isolated KC were treated with Zymosan (0.5mg/ml) in addition to JWH-133 (5μM). The thromboxane (TX) B2 levels in the perfusate and KC media were determined by ELISA. Heme oxygenase-1 (HO-1) and CB2 were analyzed by Western blot or confocal microscopy.

KEY FINDINGS

JWH-133 or GP 1a pre-treatment attenuated portal pressures following KC activation in all experimental settings. In parallel, HO-1 expression increased with JWH-133 pre-treatment. However, the inhibition of HO-1 enhanced portal hypertension, indicating the functional role of this novel pathway. In isolated KC, the expression of CB2 and HO-1 increased with Zymosan, LPS and JWH-133 treatment while TXB2 production following KC activation was attenuated by JWH-133 pre-treatment.

SIGNIFICANCE

JWH-133 or GP 1a treatment attenuates portal hypertension. HO-1 induction by JWH-133 plays a functional role. Therefore, the administration of JWH-133 or GP 1a represents a promising new treatment option for portal hypertension triggered by microbiological products.

Food-derived peroxidized fatty acids may trigger hepatic inflammation: a novel hypothesis to explain steatohepatitis

BACKGROUND & AIMS

Obesity and hepatic steatosis are frequently associated with the development of a non-alcoholic steatohepatitis (NASH). The mechanisms driving progression of a non-inflamed steatosis to NASH are largely unknown. Here, we investigated whether ingestion of peroxidized lipids, as being present in Western style diet, triggers the development of hepatic inflammation.

METHODS

Corn oil containing peroxidized fatty acids was administered to rats by gavage for 6 days. In a separate approach, hepatocytes (HC), endothelial (EC) and Kupffer cells (KC) were isolated from untreated livers, cultured, and incubated with peroxidized linoleic acid (LOOH; linoleic acid (LH) being the main fatty acid in corn oil). Samples obtained from in vivo and in vitro studies were mainly investigated by qRT-PCR and biochemical determinations of lipid peroxidation products.

RESULTS

Rat treatment with peroxidized corn oil resulted in increased hepatic lipid peroxidation, upregulation of nitric oxide synthetase-2 (NOS-2), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNFα), elevation of total nitric oxides, and increase in cd68-, cd163-, TNFα-, and/or COX-2 positive immune cells in the liver. When investigating liver cell types, LOOH elevated the secretion of TNFα, p38MAPK phosphorylation, and mRNA levels of NOS-2, COX-2, and TNFα, mainly in KC. The elevation of gene expression could be abrogated by inhibiting p38MAPK, which indicates that p38MAPK activation is involved in the pro-inflammatory effects of LOOH.

CONCLUSIONS

These data show for the first time that ingestion of peroxidized fatty acids carries a considerable pro-inflammatory stimulus into the body which reaches the liver and may trigger the development of hepatic inflammation.

NKT-cell subsets: promoters and protectors in inflammatory liver disease

Natural killer T cells (NKT) are innate-like cells which are abundant in liver sinusoids and express the cell surface receptors of NK cells (e.g., NK1.1 (mouse) or CD161+/CD56+(human)) as well as an antigen receptor (TCR) characteristic of conventional T cells. NKT cells recognize lipid antigens in the context of CD1d, a non-polymorphic MHC class I-like molecule. Activation of NKT cells has a profound influence on the immune response against tumors and infectious organisms and in autoimmune diseases. NKT cells can be categorized into at least two distinct subsets: iNKT or type I use a semi-invariant TCR, whereas type II NKT TCRs are more diverse. Recent evidence suggests that NKT-cell subsets can play opposing roles early in non-microbial liver inflammation in that type I NKT are proinflammatory whereas type II NKT cells inhibit type I NKT-mediated liver injury.

CXCR2 knockout mice are protected against DSS-colitis-induced acute kidney injury and inflammation

Organ cross talk exists in many diseases of the human and animal models of human diseases. A recent study demonstrated that inflammatory mediators can cause acute kidney injury and neutrophil infiltration in a mouse model of dextran sodium sulfate (DSS)-colitis. However, the chemokines and their receptors that may mediate distant organ effects in colitis are unknown. We hypothesized that keratinocyte chemoattractant (KC)/IL-8 receptor chemokine (C-X-C motif) ligand 2 (CXCL2) mediates DSS-colitis-induced acute kidney injury. Consistent with our hypothesis, wild-type (WT) mice developed severe colitis with DSS treatment, which was associated with inflammatory cytokine and chemokine expression and neutrophil infiltration in the colon. DSS-colitis in WT was accompanied by acute kidney injury and enhanced expression of inflammatory cytokines in the kidney. However, CXCR2 knockout mice were protected against DSS-colitis as well as acute kidney injury. Moreover, the expression of cytokines and chemokines and neutrophil infiltration was blunted in CXCR2 knockout mice in the colon and kidney. Administration of recombinant KC exacerbated DSS-colitis-induced acute kidney injury. Our results suggest that KC/IL-8 and its receptor CXCR2 are critical and major mediators of organ cross talk in DSS colitis and neutralization of CXCR2 will help to reduce the incidence of acute kidney injury due to ulcerative colitis and Crohn's disease in humans.

Role of oxidative stress in chemical allergens induced skin cells activation

Allergic contact dermatitis (ACD) is an important occupational and environmental disease caused by topical exposure to chemical allergens. It describes the adverse effects that may results when exposure to a chemical elicits a T cell-mediated inflammatory skin disease. The ability of contact sensitizers to induce the oxidative stress pathway in keratinocytes and dendritic cells has been confirmed by several authors. Reactive oxygen species (ROS) can serve as essential second messengers mediating cellular responses resulting in immune cells activation. Oxidative stress may be the starter point, as it leads to the activation of transcription factors and signaling pathways, including NF-kB and p38 MAPK, which leads to the release of cytokines and chemokines. ROS are also involved in the activation of the NLRP3/NALP3 inflammasome, which is required to direct the proteolytic maturation of inflammatory cytokines such as IL-1β and IL-18, which are all integral to the process of dendritic cells mobilization, migration and functional maturation. Moreover, emerging evidence correlates ROS to changes in the constitution of the extracellular microenvironment found to facilitate ACD. The purpose of this review is to provide both conceptual and technical frameworks on the role of oxidative stress in chemical allergy.