Phase specific suppression of neutrophil function in hibernating Syrian hamster.

Hibernation consists of alternating periods of reduced metabolism (torpor) with brief periods of metabolism similar to summer euthermia (arousal). The function of the innate immune system is reduced during hibernation, of which the underlying mechanisms are incompletely understood. Here, we studied neutrophil functionality during hibernation in Syrian hamsters. The inflammatory response to LPS-induced endotoxemia is inhibited in hibernation, partly mediated by reduced IL-6 production in early arousal. Furthermore, neutrophil pathogen binding, phagocytosis and oxidative burst is profoundly reduced in early arousal. Functionality of both summer and early arousal neutrophils was repressed in plasma from early arousal and mixed plasma from early arousal and summer euthermic, but restored by summer euthermic plasma, signifying that a plasma factor in early arousal inhibits TLR-recognition. Identification of the inhibiting factor may offer a target to modulate neutrophil function with relevance to (auto-)inflammatory diseases.

Novel coronavirus SARS-CoV-2 (Covid-19) dynamics inside the human body.

A knowledge-based cybernetic framework model representing the dynamics of SARS-CoV-2 inside the human body has been studied analytically and in silico to explore the pathophysiologic regulations. The following modeling methodology was developed as a platform to introduce a predictive tool supporting a therapeutic approach to Covid-19 disease. A time-dependent nonlinear system of ordinary differential equations model was constructed involving type-I cells, type-II cells, SARS-CoV-2 virus, inflammatory mediators, interleukins along with host pulmonary gas exchange rate, thermostat control, and mean pressure difference. This formalism introduced about 17 unknown parameters. Estimating these unknown parameters requires a mathematical association with the in vivo sparse data and the dynamic sensitivities of the model. The cybernetic model can simulate a dynamic response to the reduced pulmonary alveolar gas exchange rate, thermostat control, and mean pressure difference under a very critical condition based on equilibrium (steady state) values of the inflammatory mediators and system parameters. In silico analysis of the current cybernetical approach with system dynamical modeling can provide an intellectual framework to help experimentalists identify more active therapeutic approaches.

C reactive protein impairs adaptive immunity in immune cells of patients with melanoma.

BACKGROUND: High C reactive protein (CRP) levels have been reported to be associated with a poor clinical outcome in a number of malignancies and with programmed cell death protein 1 immune checkpoint blockade in patients with advanced cancer. Little is known about the direct effects of CRP on adaptive immunity in cancer. Therefore, we investigated how CRP impacted the function of T cells and dendritic cells (DCs) from patients with melanoma. METHODS: The effects of CRP on proliferation, function, gene expression and phenotype of patient T cells and DCs, and expansion of MART-1 antigen-specific T cells were analyzed by multicolor flow cytometry and RNA-seq. Additionally, serum CRP levels at baseline from patients with metastatic melanoma treated on the Checkmate-064 clinical trial were assessed by a Luminex assay. RESULTS: In vitro, CRP inhibited proliferation, activation-associated phenotypes and the effector function of activated CD4+ and CD8+ T cells from patients with melanoma. CRP-treated T cells expressed high levels of interleukin-1ß, which is known to enhance CRP production from the liver. CRP also suppressed formation of the immune synapse and inhibited early events in T-cell receptor engagement. In addition, CRP downregulated the expression of costimulatory molecules on mature DCs and suppressed expansion of MART-1-specific CD8+ T cells in a dose-dependent manner by impacting on both T cells and antigen-presenting cells. High-serum CRP levels at baseline were significantly associated with a shorter survival in both nivolumab-treated and ipilimumab-treated patients. CONCLUSIONS: These findings suggest that high levels of CRP induce an immunosuppressive milieu in melanoma and support the blockade of CRP as a therapeutic strategy to enhance immune checkpoint therapies in cancer. TRIAL REGISTRATION NUMBER: NCT01783938 and NCT02983006.

Serum amyloid A exhibits pH dependent antibacterial action and contributes to host defense against Staphylococcus aureus cutaneous infection.

Serum amyloid A (SAA), one of the major highly conserved acute-phase proteins in most mammals, is predominantly produced by hepatocytes and also by a variety of cells in extrahepatic tissues. It is well-known that the expression of SAA is sharply increased in bacterial infections. However, the exact physiological function of SAA during bacterial infection remains unclear. Herein, we showed that SAA expression significantly increased in abscesses of Staphylococcus aureus cutaneous infected mice, which exert direct antibacterial effects by binding to the bacterial cell surface and disrupting the cell membrane in acidic conditions. Mechanically, SAA disrupts anionic liposomes by spontaneously forming small vesicles or micelles under acidic conditions. Especially, the N-terminal region of SAA is necessary for membrane disruption and bactericidal activity. Furthermore, we found that mice deficient in SAA1/2 were more susceptible to infection by S. aureus In addition, the expression of SAA in infected skin was regulated by interleukin-6. Taken together, these findings support a key role of the SAA in host defense and may provide a novel therapeutic strategy for cutaneous bacterial infection.

Evaluation of lung parenchyma, blood vessels, and peripheral blood lymphocytes as a potential source of acute phase reactants in patients with COPD.

Background: Previous studies have shown that the arterial wall is a potential source of inflammatory markers in COPD. Here, we sought to compare the expression of acute phase reactants (APRs) in COPD patients and controls both at the local (pulmonary arteries and lung parenchyma) and systemic (peripheral blood leukocytes and plasma) compartments. Methods: Consecutive patients undergoing elective surgery for suspected primary lung cancer were eligible for the study. Patients were categorized either as COPD or control group based on the spirometry results. Pulmonary arteries and lung parenchyma sections, peripheral blood leukocytes, and plasma samples were obtained from all participants. Gene expression levels of C-reactive protein (CRP) and serum amyloid A (SAA1, SAA2, and SAA4) were evaluated in tissue samples and peripheral blood leukocytes by reverse transciption-PCR. Plasma CRP and SAA protein levels were measured by enzyme-linked immunosorbent assays. Proteins were evaluated in paraffin-embedded lung tissues by immunohistochemistry. Results: A total of 40 patients with COPD and 62 controls were enrolled. We did not find significant differences in the gene expression between COPD and control group. Both CRP and SAA were overexpressed in the lung parenchyma compared with pulmonary arteries and peripheral blood leukocytes. The expression of SAA was significantly higher in the lung parenchyma than in the pulmonary artery (2-fold higher for SAA1 and SAA4, P=0.015 and P<0.001, respectively; 8-fold higher for SAA2, P<0.001) and peripheral blood leukocytes (16-fold higher for SAA1, 439-fold higher for SAA2, and 5-fold higher for SAA4; P<0.001). No correlation between plasma levels of inflammatory markers and their expression in the lung and peripheral blood leukocytes was observed. Conclusions: The expression of SAA in lung parenchyma is higher than in pulmonary artery and peripheral blood leukocytes. Notably, no associations were noted between lung expression of APRs and their circulating plasma levels, making the leakage of inflammatory proteins from the lung to the bloodstream unlikely. Based on these results, other potential sources of systemic inflammation in COPD (eg, the liver) need further scrutiny.

Acute Phase Proteins in Marine Mammals: State of Art, Perspectives and Challenges.

The term "acute phase response" (APR) is referred to a nonspecific and complex reaction of an organism that occurs shortly after any tissue damage, such as infection, trauma, neoplasia, inflammation, and stress. The APR can be identified and monitored with some laboratory tests, such as the concentration of several plasma proteins, the acute phase proteins (APPs). The APPs are components of the non-specific innate immune response, and their plasma concentration is proportional to the severity and/or the extent of tissue damage. The evaluation of health status of marine mammals is difficult because the classical clinical signs of illness used for human and domestic animals are difficult to recognize and understand. For this reason, in the past years, several efforts were done to identify laboratory markers of disease in these animals. The APPs have demonstrated their role as early markers of inflammation in veterinary medicine, thus several APPs were tested in marine mammals, such as C-reactive protein (CRP), serum amyloid-A (SAA), and Haptoglobin (Hp). However, the difficulty to extrapolate the knowledge about APPs in one species to another, the lack of specie-specific reagents, the absence of data about negative APPs have hampered their extent use in marine mammals. Herein, the state of art of APPs in marine mammals is reviewed, with particular attention to pre-analytical and analytical factors that should be taken into account in validation and interpretation of APPs assays. Moreover, the current application, potential utility and the future developments of APPs in marine mammals is highlighted and discussed.

Chronic inflammation in adult familial Mediterranean fever patients: underlying causes and association with amyloidosis.

Background: Chronic inflammation, as determined by persistently elevated acute-phase reactants in attack-free periods, can occasionally be observed in patients with familial Mediterranean fever (FMF) and is suggested to be a risk factor for the development of amyloidosis. We aimed to investigate the underlying causes of chronic inflammation in FMF patients and its association with amyloidosis in long-term follow-up. Method: Electronic medical records of FMF patients who had regular follow-up for ≥ 5 years in our cohort were utilized. As part of routine evaluation, detailed history, physical examination, and pertinent laboratory and radiographic investigations were performed in all patients to determine potential causes of elevated C-reactive protein (CRP) levels. Results: The study included 146 FMF patients who had no evidence of amyloidosis at baseline and had regular follow-up for ≥ 5 years. Thirty-seven patients (25.3%) were found to have chronic inflammation in the disease course. Twenty-five (67.5%) of them had either very frequent attacks or chronic manifestations of disease. In the entire study group, amyloidosis developed in five patients (3.42%) during the 5 year follow-up, four in the FMF with chronic inflammation group (10.8%), and only one of the 109 patients without chronic inflammation (odds ratio 13.09, 95% confidence interval 1.41-121.2). Conclusions: The results suggest that persistently high CRP levels during the attack-free periods may be a strong risk factor for the development of amyloidosis in patients with FMF. The vast majority of FMF patients with chronic inflammation had active FMF.

Marital distress, depression, and a leaky gut: Translocation of bacterial endotoxin as a pathway to inflammation.

BACKGROUND: Marital distress and depression work in tandem to escalate risks for inflammation-related disorders. Translocation of bacterial endotoxin (lipopolysaccharide, LPS) from the gut microbiota to blood circulation stimulates systemic inflammatory responses. METHODS: To investigate increased gut permeability (a "leaky gut") as one potential mechanistic pathway from marital distress and depression to heightened inflammation, this secondary analysis of a double-blind, randomized crossover study examined serial assessments of two endotoxin biomarkers, LPS-binding protein (LBP) and soluble CD14 (sCD14), as well as C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α) during two separate 9.5 h visits. The 43 (N = 86) healthy married couples, ages 24-61 (mean = 38.22), discussed a marital disagreement during both visits; behavioral coding of these interactions provided data on hostile marital behaviors, a hallmark of marital distress. The Structured Diagnostic Interview for DSM-IV assessed participants' mood disorder history. RESULTS: Participants with more hostile marital interactions had higher LBP than those who were less hostile. Additionally, the combination of more hostile marital interactions with a mood disorder history was associated with higher LBP/sCD14 ratios. Higher LBP and LBP/sCD14 were associated with greater CRP production; for example, only 21% of low LBP participants (lowest quartile) had average CRP across the day > 3, compared to 79% of those in the highest quartile. Higher sCD14 was associated with higher IL-6. CONCLUSIONS: These bacterial LPS translocation data illustrate how a distressed marriage and a mood disorder history can promote a proinflammatory milieu through increased gut permeability, thus fueling inflammation-related disorders.

Interplay between innate immunity and iron metabolism after acute pancreatitis.

Emerging evidence shows that chronic low-grade inflammation and changes in markers of innate immunity are implicated in a range of metabolic abnormalities following an episode of acute pancreatitis. Also, deranged iron metabolism has been linked to type 2 diabetes mellitus, gestational diabetes, and new-onset diabetes after pancreatitis - the conditions characterized by high haemoglobin glycation index (HGI). This study aimed to investigate the associations between markers of innate immunity and iron metabolism in individuals after acute pancreatitis. Fasting blood samples were collected to analyse lipopolysaccharide binding protein (LBP), interleukin (IL)-6, tumor necrosis factor-α, hepcidin, ferritin, soluble transferrin receptor, HbA1c, and glucose. Participants were categorized into two groups: low HGI and high HGI. Linear regression analyses were conducted, and potential confounders (age, sex, ethnicity, body mass index, diabetes mellitus status, smoking status, aetiology of pancreatitis, duration, recurrence, and severity of pancreatitis) were adjusted for in 5 statistical models. A total of 93 patients following an episode of acute pancreatitis were included, of who 40 (43%) had high HGI. In the overall cohort, LBP was significantly associated with hepcidin and ferritin, and IL-6 was significantly associated with hepcidin, consistently in all the models. Further, LBP contributed to 7.7% and 9.5% of variance in hepcidin and ferritin levels, respectively, whereas IL-6 contributed to 5.3% of hepcidin variance. Upon subgroup analysis, the observed LBP associations were maintained in the high HGI subgroup only and the IL-6 association in the low HGI subgroup only. No consistently significant associations were found between any of the other markers. The interplay between LBP, IL-6, hepcidin, and ferritin characterizes metabolic derangements after acute pancreatitis and may play a role in the pathogenesis of new-onset diabetes after pancreatitis.

IL-1ß/IL-6/CRP and IL-18/ferritin: Distinct Inflammatory Programs in Infections.

The host inflammatory response against infections is characterized by the release of pro-inflammatory cytokines and acute-phase proteins, driving both innate and adaptive arms of the immune response. Distinct patterns of circulating cytokines and acute-phase responses have proven indispensable for guiding the diagnosis and management of infectious diseases. This review discusses the profiles of acute-phase proteins and circulating cytokines encountered in viral and bacterial infections. We also propose a model in which the inflammatory response to viral (IL-18/ferritin) and bacterial (IL-6/CRP) infections presents with specific plasma patterns of immune biomarkers.

A re-examination of the role of the acute phase protein response in innate cancer defence.

Anti-cancer host defense mechanisms are traditionally considered to consist of tumor suppressor genes and immune surveillance by cells of the innate and adaptive immune systems. However, there is mounting evidence that components of the acute phase protein response (APPR), and, in particular, certain cationic host defense peptides (HDPs), also contribute to anti-cancer host defense. In a number of in vitro studies, certain HDPs have been shown to be cytotoxic to tumor cells either directly through cancer cell membrane destabilization and lysis or through the initiation of apoptosis in the cancer cell. In addition, many cancer cells elaborate the pro-inflammatory cytokine interleukin-6, which in turn produces an APPR that involves the release of HDPs. It is therefore possible that the release of pro-inflammatory cytokines by cancer cells initiates a poorly understood anti-tumor response by the host that involves HDP induction. We hypothesize that the APPR may form an important anti-cancer host defense response. This may be an important consideration in light of cancer treatments designed to decrease systemic inflammation. Blunting of the anti-cancer effect of the APPR may also contribute to the increased cancer rates seen in chronic immunosuppressive states.

Vaginal Inflammation: Association between Leukocyte Concentration and Levels of Immune Mediators.

PROBLEM: A wide variety of mediators are involved in inflammatory processes. However, the identity of those participating in vaginal immune responses has not been established. We correlated extracellular matrix metalloproteinase inducer (EMMPRIN), matrix metalloproteinase-8 (MMP-8), hyaluronan (HA), hyaluronidase-1 (Hyal-1), human ß-defensin-2 (hBD2), and neutrophil gelatinase-associated lipocalin (NGAL) concentrations with the extent of leukocyte infiltration into the vagina and suggest their participation in vaginal inflammation. METHODS OF STUDY: Vaginal fluid was obtained from 233 women seen at the outpatient clinic in the Department of Obstetrics and Gynecology at Campinas University, Brazil. The magnitude of vaginal inflammation was determined by the leukocyte count on vaginal smears and categorized as no inflammation (0 leukocytes/field), moderate inflammation (1-4 leukocytes/field), and intense inflammation (>4 leukocytes/field). Concentrations of EMMPRIN, MMP-8, HA, Hyal-1, hBD2, and NGAL were determined in vaginal fluid by ELISA. RESULTS: EMMPRIN, MMP-8, HA, hBD2, and NGAL concentration increased with elevated leukocyte numbers (P < 0.05), while Hyal-1 did not. EMMPRIN concentrations were correlated with HA and MMP-8 levels. CONCLUSION: EMMPRIN, MMP-8, HA, ß-defensin, and NGAL are elevated in women with vaginal inflammation.

Interactions between Hepatitis C Virus and the Human Apolipoprotein H Acute Phase Protein: A Tool for a Sensitive Detection of the Virus.

The Hepatitis C virus (HCV) infection exhibits a high global prevalence frequently associated with hepatocellular carcinoma, taking years to develop. Despite the standardization of highly sensitive HCV quantitative RT-PCR (qRT-PCR) detection methods, false-negative diagnoses may be generated with current methods, mainly due to the presence of PCR inhibitors and/or low viral loads in the patient's sample. These false-negative diagnoses impact both public health systems, in developing countries, and an in lesser extent, in developed countries, including both the risk of virus transmission during organ transplantation and/or blood transfusion and the quality of the antiviral treatment monitoring. To adopt an appropriate therapeutic strategy to improve the patient's prognosis, it is urgent to increase the HCV detection sensitivity. Based upon previous studies on HBV, we worked on the capacity of the scavenger acute phase protein, Apolipoprotein H (ApoH) to interact with HCV. Using different approaches, including immunoassays, antibody-inhibition, oxidation, ultracentrifugation, electron microscopy and RT-PCR analyses, we demonstrated specific interactions between HCV particles and ApoH. Moreover, when using a two-step HCV detection process, including capture of HCV by ApoH-coated nanomagnetic beads and a home-made real-time HCV-RT-PCR, we confirmed the presence of HCV for all samples from a clinical collection of HCV-seropositive patients exhibiting an RT-PCR COBAS® TaqMan® HCV Test, v2.0 (COBAS)-positive result. In contrast, for HCV-seropositive patients with either low HCV-load as determined with COBAS or exhibiting HCV-negative COBAS results, the addition of the two-step ApoH-HCV-capture and HCV-detection process was able to increase the sensitivity of HCV detection or more interestingly, detect in a genotype sequence-independent manner, a high-proportion (44%) of HCV/RNA-positive among the COBAS HCV-negative patients. Thus, the immune interaction between ApoH and HCV could be used as a sample preparation tool to enrich and/or cleanse HCV patient's samples to enhance the detection sensitivity of HCV and therefore significantly reduce the numbers of false-negative HCV diagnosis results.

Lipocalin-2 ensures host defense against Salmonella Typhimurium by controlling macrophage iron homeostasis and immune response.

Lipocalin-2 (Lcn2) is an innate immune peptide with pleiotropic effects. Lcn2 binds iron-laden bacterial siderophores, chemo-attracts neutrophils and has immunomodulatory and apoptosis-regulating effects. In this study, we show that upon infection with Salmonella enterica serovar Typhimurium, Lcn2 promotes iron export from Salmonella-infected macrophages, which reduces cellular iron content and enhances the generation of pro-inflammatory cytokines. Lcn2 represses IL-10 production while augmenting Nos2, TNF-α, and IL-6 expression. Lcn2(-/-) macrophages have elevated IL-10 levels as a consequence of increased iron content. The crucial role of Lcn-2/IL-10 interactions was further demonstrated by the greater ability of Lcn2(-/-) IL-10(-/-) macrophages and mice to control intracellular Salmonella proliferation in comparison to Lcn2(-/-) counterparts. Overexpression of the iron exporter ferroportin-1 in Lcn2(-/-) macrophages represses IL-10 and restores TNF-α and IL-6 production to the levels found in wild-type macrophages, so that killing and clearance of intracellular Salmonella is promoted. Our observations suggest that Lcn2 promotes host resistance to Salmonella Typhimurium infection by binding bacterial siderophores and suppressing IL-10 production, and that both functions are linked to its ability to shuttle iron from macrophages.

MCPIP1 Endoribonuclease Activity Negatively Regulates Interleukin-17-Mediated Signaling and Inflammation.

Interleukin-17 (IL-17) induces pathology in autoimmunity and infections; therefore, constraint of this pathway is an essential component of its regulation. We demonstrate that the signaling intermediate MCPIP1 (also termed Regnase-1, encoded by Zc3h12a) is a feedback inhibitor of IL-17 receptor signal transduction. MCPIP1 knockdown enhanced IL-17-mediated signaling, requiring MCPIP1's endoribonuclease but not deubiquitinase domain. MCPIP1 haploinsufficient mice showed enhanced resistance to disseminated Candida albicans infection, which was reversed in an Il17ra(-/-) background. Conversely, IL-17-dependent pathology in Zc3h12a(+/-) mice was exacerbated in both EAE and pulmonary inflammation. MCPIP1 degraded Il6 mRNA directly but only modestly downregulated the IL-6 promoter. However, MCPIP1 strongly inhibited the Lcn2 promoter by regulating the mRNA stability of Nfkbiz, encoding the IκBζ transcription factor. Unexpectedly, MCPIP1 degraded Il17ra and Il17rc mRNA, independently of the 3' UTR. The cumulative impact of MCPIP1 on IL-6, IκBζ, and possibly IL-17R subunits results in a biologically relevant inhibition of IL-17 signaling.

Predictive Role of Neutrophil Gelatinase-Associated Lipocaline in Donor-Specific Antibody-Positive and Donor-Specific Antibody-Negative Renal Transplant Patients.

BACKGROUND: Renal transplantation is the best choice for the treatment of dialysis patients with end-stage renal failure because it provides better quality of life and more life time. However, despite successful surgical techniques, immunological issues in kidney transplantation are not completely resolved. Thus, after transplantation, patients must be followed up closely. Although patient follow-up with the use of creatinine and renal biopsy are common, it is thought that biopsy is too invasive and that creatinine is unreliable. Hence, new parameters that correlate with the patient's immunological condition are needed in clinical monitoring. METHODS: One of the biomarkers that has been studied recently is neutrophil gelatinase-associated lipocalin (NGAL). Its diagnostic value in cases of acute renal failure, delayed graft function, and IgA nephropathy is widely investigated. However, data are insufficient as to whether NGAL can be used for follow-up in the chronic process after renal transplantation. We aimed to investigate the predictive value of NGAL in terms of rejection in donor-specific antibody (DSA)-positive and DSA-negative renal transplant patients. Ninety patients were included. RESULTS: We found that rejection rates were higher in patients whose NGAL values were ≥ 50 and DSA-positive. Delayed graft function was seen more frequently in patients whose NGAL values were ≥ 50. CONCLUSIONS: An increase in NGAL level does not always indicate renal injury because NGAL is also an acute-phase reactant. NGAL cannot be used alone to diagnose rejection, but, if NGAL level is high, it is necessary to study DSA, and sub-clinical rejection must be researched.

[Prokaryotic expression and immunological activity of human neutrophil gelatinase associated lipocalin].

OBJECTIVE: To construct a prokaryotic expression vector of human neutrophil gelatinase associated lipocalin (NGAL) and identify the bioactivity of the fusion protein. METHODS: The cDNA of human NGAL obtained from GenBank was linked to a cloning vector to construct the prokaryotic expression vector pCold-NGAL. Then the vector was transformed into E.coli BL21(DE3) plysS. Under the optimal induction condition, the recombinant NGAL (rNGAL) was expressed and purified by Ni Sepharose 6 Fast Flow affinity chromatography. The purity and activity of the rNGAL were respectively identified by SDS-PAGE and Western blotting combined with NGAL reagent (Latex enhanced immunoturbidimetry). RESULTS: Restriction enzyme digestion and nucleotide sequencing proved that the expression vector pCold-NGAL was successfully constructed. Under the optimal induction condition that we determined, the rNGAL was expressed in soluble form in E.coli BL21(DE3) plysS. The relative molecular mass of the rNGAL was 25 000, and its purity was more than 98.0%. Furthermore, Western blotting and immunoturbidimetry indicated that the rNGAL reacted with NGAL mAb specifically. CONCLUSION: Human rNGAL of high purity and bioactivity was successfully constructed in E.coli BL21(DE3) plysS using the expression vector pCold-NGAL.

Lipocalin-2 in the Inflammatory Activation of Brain Astrocytes.

Lipocalin-2 (LCN2), a secretory protein, regulates diverse cellular processes such as cell death/survival, cell migration/invasion, cell differentiation, iron delivery, inflammation, insulin resistance, and tissue regeneration. Recently, we reported that LCN2 is secreted by brain astrocytes under inflammatory conditions and that it promotes apoptosis, morphological changes, and migration in astrocytes both in vitro and in vivo. Activated astrocytes release LCN2 not only to induce the morphological transformation associated with reactive astrocytosis, but also to promote their own death. Under inflammatory conditions, activated astrocytes also show functional dichotomy similar to the M1/M2 phenotypes of microglia and macrophages. LCN2 is thought to be a chemokine inducer and an autocrine promoter of the classical proinflammatory activation of astrocytes. This article summarizes the current knowledge regarding the role of astrocyte-derived LCN2 as a proinflammatory mediator in the central nervous system and discusses LCN2's role in neuroinflammatory disorders.

Low dietary iron intake restrains the intestinal inflammatory response and pathology of enteric infection by food-borne bacterial pathogens.

Orally administrated iron is suspected to increase susceptibility to enteric infections among children in infection endemic regions. Here we investigated the effect of dietary iron on the pathology and local immune responses in intestinal infection models. Mice were held on iron-deficient, normal iron, or high iron diets and after 2 weeks they were orally challenged with the pathogen Citrobacter rodentium. Microbiome analysis by pyrosequencing revealed profound iron- and infection-induced shifts in microbiota composition. Fecal levels of the innate defensive molecules and markers of inflammation lipocalin-2 and calprotectin were not influenced by dietary iron intervention alone, but were markedly lower in mice on the iron-deficient diet after infection. Next, mice on the iron-deficient diet tended to gain more weight and to have a lower grade of colon pathology. Furthermore, survival of the nematode Caenorhabditis elegans infected with Salmonella enterica serovar Typhimurium was prolonged after iron deprivation. Together, these data show that iron limitation restricts disease pathology upon bacterial infection. However, our data also showed decreased intestinal inflammatory responses of mice fed on high iron diets. Thus additionally, our study indicates that the effects of iron on processes at the intestinal host-pathogen interface may highly depend on host iron status, immune status, and gut microbiota composition.

Regulation of Inflammation and Angiogenesis in Giant Cell Arteritis by Acute-Phase Serum Amyloid A.

OBJECTIVE: Giant cell arteritis (GCA) is pathologically characterized by dysfunctional angiogenesis and inflammatory cell infiltration. Acute-phase serum amyloid A (A-SAA) is an acute-phase reactant, but is also produced at sites of inflammation and may contribute to vascular inflammation in atherosclerosis. This study was undertaken to examine the effect of A-SAA on proinflammatory pathways and angiogenesis in GCA, using a novel ex vivo temporal artery tissue explant model. METHODS: Serum A-SAA levels were measured by enzyme-linked immunosorbent assay (ELISA). Temporal artery explants and peripheral blood mononuclear cell (PBMC) cultures were established from patients with GCA. Temporal artery explant morphology, viability, and spontaneous release of proinflammatory mediators following 24-hour culture were assessed by hematoxylin and eosin, calcein viability staining, and ELISA. Temporal artery explants and PBMC cultures were stimulated with A-SAA (10 µg/ml), and interleukin-6 (IL-6), IL-8, vascular endothelial growth factor, Ang2, and matrix metalloproteinase 2 (MMP-2)/MMP-9 were quantified by ELISA and gelatin zymography. The effect of conditioned medium from temporal artery explants on angiogenesis was assessed using endothelial cell Matrigel tube-formation assays. Temporal artery explants were also embedded in Matrigel, and myofibroblast outgrowth was assessed. RESULTS: Serum A-SAA levels were significantly higher in GCA patients versus healthy controls (P < 0.0001). Intact tissue morphology, cell viability, and spontaneous cytokine secretion were demonstrated in temporal artery explants. A-SAA treatment induced a significant increase in the levels of IL-6 and IL-8 from temporal artery explants (P < 0.05) and IL-8 from PBMCs (P < 0.05) compared to basal conditions. Conditioned medium from A-SAA-treated explants significantly induced angiogenic tube formation (P < 0.05 versus basal controls). Finally, A-SAA induced myofibroblast outgrowth and MMP-9 activation. CONCLUSION: Our findings demonstrate a functional role for A-SAA in regulating temporal artery inflammation, angiogenesis, and invasion, all key processes in the pathogenesis of GCA.