Crucial Inflammatory Mediator Research Articles

Multishaped bio-gold polyphenols bearing nanoparticles to promote inflammatory suppression

Green synthesis from plant waste involves the generation of functional nanoparticles (NPs), offering significant potential for a wide range of applications. Numerous studies have focused on the use of plant extracts to produce AuNPs suitable for various applications in the medical field, particularly in photothermal therapy and cancer therapy, owing to their plasmonic properties. Moreover, NP-mediated immunostimulation and immunosuppression is an intriguing field of research, focusing on how manipulation of NP physicochemical properties can influence their inter-action with immune cells and immune modulation. However, to date, few investigations have been conducted on the modulation of the inflammatory response mediated by green-synthesized nanostructures. To this aim, we synthesized AuNPs using extracts of Laurus nobilis, which exhibit high crystallinity and are inherently coated by a dense network of polyphenols, thus maintaining stability on their surface through the green synthesis approach. Then, in order to explore how these green-synthesized nanostructures can enhance or suppress the inflammatory cellular responses, we investigated the response of free polyphenols and AuNPs@polyphenols in murine bone marrow derived dendritic cells (BMDCs), by means of morphomechanical analysis and biochemical assays. Our findings demonstrated that DCs exposed to both free polyphenol extract and AuNPs@polyphenols were able to inhibit the secretion of crucial inflammatory mediators in response to lipopolysaccharide (LPS) administration. Therefore, polyphenols immobilized on Au surface were more effective in the inflammation suppression. These evidence paving the way for a powerful strategy to develop edible anti-inflammatory adjuvants, overcoming the limitations associated with the use of free polyphenols in clinical practice.

From Gasotransmitter to Immunomodulator: The Emerging Role of Hydrogen Sulfide in Macrophage Biology.

Hydrogen sulfide (H2S) has been increasingly recognized as a crucial inflammatory mediator in immune cells, particularly macrophages, due to its direct and indirect effects on cellular signaling, redox homeostasis, and energy metabolism. The intricate regulation of endogenous H2S production and metabolism involves the coordination of transsulfuration pathway (TSP) enzymes and sulfide oxidizing enzymes, with TSP's role at the intersection of the methionine pathway and glutathione synthesis reactions. Additionally, H2S oxidation mediated by sulfide quinone oxidoreductase (SQR) in mammalian cells may partially control cellular concentrations of this gasotransmitter to induce signaling. H2S is hypothesized to signal through the posttranslational modification known as persulfidation, with recent research highlighting the significance of reactive polysulfides, a derivative of sulfide metabolism. Overall, sulfides have been identified as having promising therapeutic potential to alleviate proinflammatory macrophage phenotypes, which are linked to the exacerbation of disease outcomes in various inflammatory conditions. H2S is now acknowledged to have a significant influence on cellular energy metabolism by affecting the redox environment, gene expression, and transcription factor activity, resulting in changes to both mitochondrial and cytosolic energy metabolism processes. This review covers recent discoveries pertaining to the involvement of H2S in macrophage cellular energy metabolism and redox regulation, and the potential implications for the inflammatory response of these cells in the broader framework of inflammatory diseases.

Elevated IL-6 plasma levels are associated with GAD antibodies-associated autoimmune epilepsy.

Antibodies against glutamic acid decarboxylase (GADA) are present in multiple neurological manifestations, such as stiff-person syndrome, cerebellar ataxia, limbic encephalitis, and epilepsy. Increasing data support the clinical significance of GADA as an autoimmune etiology of epilepsy, however, there is not yet definitive evidence to confirm the pathogenic link between GADA and epilepsy. Interleukin-6 (IL-6), a pro-convulsive and neurotoxic cytokine, and interleukin-10 (IL-10), an anti-inflammatory and neuroprotective cytokine, are crucial inflammatory mediators in the brain. Increased production of IL-6 and its association with epileptic disease profiles are well established, suggesting the presence of chronic systemic inflammation in epilepsy. Therefore, in this study, we investigated the association of plasma cytokine concentrations of IL-6 and IL-10 and their ratio with GADA in patients with drug-resistant epilepsy. Interleukin-6 and IL-10 concentrations were measured by ELISA in plasma, and the IL-6/IL-10 ratio was calculated in a cross-sectional cohort of 247 patients with epilepsy who had their GADA titers measured previously for their clinical significance in epilepsy. Based on GADA titers, patients were grouped as GADA negative (n = 238), GADA low positive (antibody titers < 1,000 RU/mL, n = 5), and GADA high positive (antibody titers ≥ 1,000 RU/mL, n = 4). Median IL-6 concentrations were significantly higher in patients with high GADA positivity [2.86 pg/mL, interquartile range (IQR) = 1.90-5.34 pg/mL] than in GADA-negative patients [1.18 pg/mL, interquartile range (IQR) = 0.54-2.32 pg/mL; p = 0.039]. Similarly, IL-10 concentrations were also higher in GADA high-positive patients [1.45 pg/mL, interquartile range (IQR) = 0.53-14.32 pg/mL] than in GADA-negative patients [0.50 pg/mL, interquartile range (IQR) = 0.24-1.00 pg/mL], however, the difference was not statistically significant (p = 0.110). Neither IL-6 nor IL-10 concentrations were different between GADA-negative and GADA low-positive patients (p > 0.05) or between GADA low-positive or GADA high-positive patients (p > 0.05). The IL-6/IL-10 ratio was also similar among all the study groups. Increased circulatory concentrations of IL-6 are associated with high GADA titers in patients with epilepsy. These data provide additional pathophysiological significance of IL-6 and help to further describe the immune mechanisms involved in the pathogenesis of GADA-associated autoimmune epilepsy.

CXCL10 Chemokine: A Critical Player in RNA and DNA Viral Infections.

Chemokines constitute a group of small, secreted proteins that regulate leukocyte migration and contribute to their activation. Chemokines are crucial inflammatory mediators that play a key role in managing viral infections, during which the profile of chemokine expression helps shape the immune response and regulate viral clearance, improving clinical outcome. In particular, the chemokine ligand CXCL10 and its receptor CXCR3 were explored in a plethora of RNA and DNA viral infections. In this review, we highlight the expression profile and role of the CXCL10/CXCR3 axis in the host defense against a variety of RNA and DNA viral infections. We also discuss the interactions among viruses and host cells that trigger CXCL10 expression, as well as the signaling cascades induced in CXCR3 positive cells.

Rab44 regulates murine mast cell–driven anaphylaxis through kinesin-1–dependent secretory granule translocation

Mast cells (MCs) are key effectors of the allergic response. Following the cross-linking of IgE receptors (FcεRIs), they release crucial inflammatory mediators through degranulation. Although degranulation depends critically on secretory granule (SG) trafficking toward the plasma membrane, the molecular machinery underlying this transport has not been fully characterized. This study analyzed the function of Rab44, a large, atypical Rab guanosine triphosphatase highly expressed in MC, in the MC degranulation process. Murine knockout (KO) mouse models (KORab44 and DKOKif5b/Rab44) were used to perform passive cutaneous anaphylaxis experiments and analyze granule translocation in bone marrow-derived MCs during degranulation. This study demonstrate that mice lacking Rab44 (KORab44) in their bone marrow-derived MCs are impaired in their ability to translocate and degranulate SGs at the plasma membrane on FcεRI stimulation. Accordingly, KORab44 mice were less sensitive to IgE-mediated passive cutaneous anaphylaxis invivo. Alack of Rab44 did not impair early FcεRI-stimulated signaling pathways, microtubule reorganization, lipid mediator release, or cytokine secretion. Mechanistically, Rab44 appears to interact with and function as part of the previously described kinesin-1-dependent transport pathway. These results highlight a novel role of Rab44 as a regulator of SG transport during degranulation and anaphylaxis acting through the kinesin-1-dependent microtubule transport machinery. Rab44 can thus be considered a potential target for modulating MC degranulation and inhibiting IgE-mediated allergic reactions.

Comparative analysis of the role of mast cells in murine asthma models using Kit-sufficient mast cell-deficient animals.

Asthma is a frequent chronic disease that can potentially severely affect the respiratory capacity and well-being of patients. Mast cells (MCs) are regarded as major players in human asthma due to their capacity to release crucial inflammatory mediators following allergen exposure. However, unambiguous characterization of their role in animal models has long been hindered by the unavailability of specific MC-deficient models lacking confounding MC-unrelated effects. This study aims to examine the role of MCs in Kit-sufficient MC-deficient Cpa3Cre/+ mice. We used a variety of models of acute and chronic asthma employing distinct routes and regimes of sensitization. These sensitizations were done via the peritoneal cavity, the skin, or the lung. Additionally, different allergens, i.e. ovalbumin and house dust mite extract, were used. Our results show that the absence of MCs had no impact on the severity of allergic airway inflammation in any of the tested mouse models, as measured by leukocyte infiltration in the airways, cytokine expression, antibody production, airway hyper-responsiveness and mucus production. This indicates that MCs do not play a major role in murine allergic airway inflammation.

A targeted polypeptide-based nanoconjugate as a nanotherapeutic for alcohol-induced neuroinflammation

Alcohol abuse induces the expression of inflammatory mediators by activating the immune receptors to trigger neuroinflammation and brain damage; however, therapies that reduce neuroimmune system activation may protect against alcohol's damaging effects. Curcuminoids possess anti-inflammatory properties but suffer from low bioavailability; therefore, we designed a new receptor-targeted biodegradable star-shaped crosslinked polypeptide polymer that bears propargylamine moieties and bisdemethoxycurcumin (StClPr-BDMC-ANG) as an enhanced anti-inflammatory therapeutic that penetrates the blood–brain-barrier and ameliorates alcohol-induced neuroinflammation. StClPr-BDMC-ANG administration maintains the viability of primary glia and inhibits the ethanol-induced upregulation of crucial inflammatory mediators in the prefrontal and medial cortex in a mouse model of chronic ethanol consumption. StClPr-BDMC-ANG treatment also suppresses the ethanol-mediated downregulation of microRNAs known to negatively modulate neuroinflammation in the brain cortex (miRs 146a-5p and let-7b-5p). In summary, our results demonstrate the attenuation of alcohol-induced neuroinflammation by an optimized and targeted polypeptide-based nanoconjugate of a curcuminoid.

Chemokines and chemokine receptors during COVID-19 infection.

Chemokines are crucial inflammatory mediators needed during an immune response to clear pathogens. However, their excessive release is the main cause of hyperinflammation. In the recent COVID-19 outbreak, chemokines may be the direct cause of acute respiratory disease syndrome, a major complication leading to death in about 40% of severe cases. Several clinical investigations revealed that chemokines are directly involved in the different stages of SARS-CoV-2 infection. Here, we review the role of chemokines and their receptors in COVID-19 pathogenesis to better understand the disease immunopathology which may aid in developing possible therapeutic targets for the infection.

Within-host mathematical modeling on crucial inflammatory mediators and drug interventions in COVID-19 identifies combination therapy to be most effective and optimal

The unprecedented Covid-19 pandemic has resulted in more than 14.75 million infections and 6, 10, 839 deaths in 212 countries. Appropriate interventions can decrease the rate of Covid-19 related mortality. Fast track clinical trials around the world are addressing the efficacy of individual pharmaceutical agent acting at various stages of pathogenesis. However, lessons learnt while dealing with past viral epidemics mandates, simultaneous use of such drugs in combination amongst different populations. Mathematical modelling studies can be extremely helpful in understanding the efficacy of drugs both individually and in combination. The current within-host mathematical model studies the natural history of Covid-19 in terms of complex interplay of virus replication and behaviour of host immune response. Additionally it studies the role of various drugs at various stages of pathogenesis. The model was validated by generating two-parameter heat plots, representing the characteristics of Covid-19, the sensitivity analysis identified the crucial parameters. The efficacy of interventions was assessed by optimal control problem. The model dynamics exhibited disease-free equilibrium and the infected equilibrium with their stability, based on the reproduction number R0, the transcritical bifurcation observed at R0=1. The burst rate and the natural death rate of the virus were observed as most significant parameters in the life-threatening Covid-19 pneumonia. The antiviral drugs affecting viral replication and those modulating the immune response, reduce the infected cells and viral load significantly. However, the yield was optimal and most effective when the combination therapy involving one or more antiviral and one or more immunomodulating drugs were administered together. These findings may help physicians with early decision making in treatment of life-threatening Covid-19 infection.

Activation of the IL-1β/KLF2/HSPH1 pathway promotes STAT3 phosphorylation in alveolar macrophages during LPS-induced acute lung injury.

Acute lung injury (ALI) is a lethal disease with diffuse lung inflammation, in which JAK/STAT3 signaling has been well recognized for its role in initiating and amplifying inflammatory processes. However, the mechanism for the enhancement and maintenance of signal transducer and activator of transcription 3 (STAT3) activation has not yet been clearly demonstrated in ALI. In the present work, we established a lipopolysaccharide (LPS)-induced ALI rat model through intratracheal instillation and isolated the alveolar macrophages (AMs) from the rats in the model. We demonstrated that the expression of Kruppel-like factor 2 (KLF2) significantly decreased in the AMs from LPS-induced ALI rats (LPS-AMs) as compared with the AMs from control rats (NC-AMs). Overexpressing KLF2 in LPS-AMs inhibited the phosphorylation of STAT3 and reduced the levels of STAT3 target genes, including matrix metalloproteinase (MMP)-2/9 (MMP-2/9). Further investigation indicated that KLF2 trans-inhibited heat shock protein H1 (HSPH1), which interacted with STAT3 and enhanced its phosphorylation. As a crucial inflammatory mediator in ALI, interleukin-1β (IL-1β) induced the down-regulation of KLF2 in LPS-AMs, as interrupting IL-1β signaling in LPS-AMs by antibody neutralization or IL1R1 knockdown rescued the expression of KLF2. Consistently, stimulating NC-AMs with IL-1β decreased KLF2 and increased HSPH1, while overexpression of KLF2 suppressed IL-1β-induced HSPH1. Additionally, in vivo studies showed that treatment with an IL-1β antibody or HSPH1 inhibitor alleviated lung injury in ALI rats, as well as decreased the levels of p-STAT3 and MMP-2/9. In conclusion, activation of the IL-1β/KLF2/HSPH1 pathway facilitated STAT3 phosphorylation in AMs, which exacerbated pulmonary inflammation in ALI.

Increased Frequency of Peripheral B and T Cells Expressing Granulocyte Monocyte Colony-Stimulating Factor in Rheumatoid Arthritis Patients.

Granulocyte monocyte colony-stimulating factor (GM-CSF) is currently considered a crucial inflammatory mediator and a novel therapeutic target in rheumatoid arthritis (RA), despite the fact that its precise cellular sources remain uncertain. We studied the expression of GM-CSF in peripheral lymphocytes from RA patients and its change with antirheumatic therapies. Intracellular GM-CSF expression was assessed by flow cytometry in stimulated peripheral B (CD19+) and T (CD3+) cells from RA patients (n = 40), disease (n = 31 including osteoarthritis n = 15, psoriatic arthritis n = 10, and systemic rheumatic diseases n = 6) and healthy (n = 16) controls. The phenotype of GM-CSF+ B cells was assessed as well as longitudinal changes in GM-CSF+ lymphocytes during methotrexate (MTX, n = 10) or anti-tumor necrosis factor (anti-TNF, n = 10) therapy. Among untreated RA patients with active disease (Disease Activity Score 28-C-reactive protein = 5.6 ± 0.89) an expanded population of peripheral GM-CSF+ B (4.1 ± 2.2%) and T (3.4 ± 1.6%) cells was detected compared with both disease (1.7 ± 0.9%, p < 0.0001 and 1.7 ± 1.3%, p < 0.0001, respectively) and healthy (0.3 ± 0.2%, p < 0.0001 and 0.6 ± 0.6%, p < 0.0001) controls. RA GM-CSF+ B cells displayed more commonly a plasmablast or transitional phenotype (37.12 ± 18.34% vs. 14.26 ± 9.46%, p = 0.001 and 30.49 ± 15.04% vs. 2.45 ± 1.84%, p < 0.0001, respectively) and less a memory phenotype (21.46 ± 20.71% vs. 66.99 ± 16.63%, p < 0.0001) compared to GM-CSF- cells. GM-CSF expression in RA patients did not correlate to disease duration, activity or serological status. Anti-TNF treatment led to a statistically significant decrease in GM-CSF+ B and T cells while MTX had no significant effect. This is the first study showing an expanded population of GM-CSF+ B and T lymphocytes in patients with active RA which declined after anti-TNF therapy.

CXCL5 as an autocrine or paracrine cytokine is associated with proliferation and migration of hepatoblastoma HepG2 cells.

C-X-C motif chemokine ligand 5 (CXCL5) is a CXC-type chemokine that is a crucial inflammatory mediator and a powerful attractant for granulocytic immune cells. Increasing evidence has indicated that CXCL5 is involved in the tumorigenesis of various malignancies. The present investigation demonstrated that CXCL5 was expressed in both hepatoblastoma HepG2 cells and liver stellate LX-2 cells, and CXCL5's receptor C-X-C chemokine receptor type 2 (CXCR2) was expressed in HepG2 cells by reverse transcription-polymerase chain reaction (RT-PCR), western blotting and ELISA assays. Cell counting kit-8, colony formation and Transwell assays revealed that exogenous CXCL5 expression efficiently promoted proliferation, colony formation and migration of HepG2 cells. To explore the autocrine and paracrine roles of CXCL5 in the oncogenic potential of HepG2 cells, HepG2 cells overexpressing CXCL5 and LX-2 cells overexpressing CXCL5 were successfully constructed by gene transfection. Similarly, overexpression of CXCL5 in HepG2 also enhanced proliferation, colony formation and migration of HepG2 cells. Furthermore, the condition medium of LX-2 cells overexpressing CXCL5 affected the proliferation and migration of HepG2 cells. RT-PCR and western blotting assays were also conducted to explore whether overexpression of CXCL5 in HepG2 modulated the expression of genes. The results revealed that overexpression of CXCL5 regulated the expression of several genes, including N-myc downregulated gene 3,w B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein, P53, vascular endothelial growth factor, interleukin (IL)-18, IL-1β and cystathionine-γ-lyase. In conclusion, the present findings indicate that CXCL5/CXCR2 axis contributes to the oncogenic potential of hepatoblastoma via autocrine or paracrine pathways by regulating expression of genes associated with the progression of carcinoma.

Profile of bioactive compounds in Nymphaea alba L. leaves growing in Egypt: hepatoprotective, antioxidant and anti-inflammatory activity

BackgroundNymphaea alba L. represents an interesting field of study. Flowers have antioxidant and hepatoprotective effects, rhizomes constituents showed cytotoxic activity against liver cell carcinoma, while several Nymphaea species have been reported for their hepatoprotective effects. Leaves of N. alba have not been studied before. Therefore, in this study, in-depth characterization of the leaf phytoconstituents as well as its antioxidant and hepatoprotective activities have been performed where N. alba leaf extract was evaluated as a possible therapeutic alternative in hepatic disorders.MethodsThe aqueous ethanolic extract (AEE, 70%) was investigated for its polyphenolic content identified by high-resolution electrospray ionisation mass spectrometry (HRESI-MS/MS), while the petroleum ether fraction was saponified, and the lipid profile was analysed using gas liquid chromatography (GLC) analysis and compared with reference standards. The hepatoprotective activity of two doses of the extract (100 and 200 mg/kg; P.O.) for 5 days was evaluated against CCl4-induced hepatotoxicity in male Wistar albino rats, in comparison with silymarin. Liver function tests; aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma glutamyl transpeptidase (GGT) and total bilirubin were performed. Oxidative stress parameters; malondialdehyde (MDA), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), total antioxidant capacity (TAC) as well as inflammatory mediator; tumour necrosis factor (TNF)-α were detected in the liver homogenate. Histopathological examination of the liver and immunohistochemical staining of caspase-3 were performedResultsFifty-three compounds were tentatively identified for the first time in N.alba leaf extract, where ellagitannins represent the main identified constituents. Nine hydrocarbons, two sterols and eleven fatty acids were identified in the petroleum ether extract where, palmitic acid and linolenic acids represented the major saturated and unsaturated fatty acid respectively. N.alba AEE significantly improved the liver function, oxidative stress parameters as well as TNF-α in addition to the amelioration of histopathological features of the liver and a profound decrease in caspase-3 expression.ConclusionThese results shed light on the hepatoprotective effect of N. alba that is comparable with that of silymarin. The antioxidant activities of N. alba extract in addition to the inhibition of crucial inflammatory mediator, as TNF-α, might be the possible hepatoprotective mechanisms.

Evaluation of the in vitro anti-atherogenic activities of goat milk and goat dairy products

Given that goat milk and dairy products should be consumed daily according to suggestions based on Mediterranean diet, the current study evaluates the anti-atherogenic properties of goat milk and goat dairy products (yogurt and white cheese). Total lipids (TLs) of all three samples were extracted by the method of Bligh and Dyer and further separated into total polar lipids (TPLs) and total neutral lipids (TNLs) by counter current distribution. The fatty acid profiles of TPL and TNL of all three samples were determined by gas chromatography analysis. TL and TPL were tested to determine whether they induce platelet aggregation or inhibit platelet aggregation induced by the platelet-activating factor (PAF). The most active lipids were found in goat white cheese (i.e., since they showed lower IC50 values in both TL and TPL samples than corresponding fractions of goat milk and goat yogurt), so the TPL of goat white cheese were further separated by preparative thin-layer chromatography (TLC). The obtained polar lipid fractions after TLC separation were also tested for their biological activity. All the samples’ lipids, and especially the polar ones, were found to exhibit strong anti-atherogenic activities. This fact highlights the nutritional value of goat dairy products in terms of cardioprotection, as PAF is a crucial inflammatory mediator that is implicated in the mechanism of atherogenesis.

Brain Death in Combination with Warm Ischemic Stress during Isolation Procedures Induces the Expression of Crucial Inflammatory Mediators in the Isolated Islets

Tissue factor (TF) and monocyte chemoattractant protein-1 (MCP-1) expressed on the islets have been identified as the main trigger of the instant blood-mediated inflammatory reaction (IBMIR) in islet transplantation. Because the key steps that directly induce TF and MCP-1 remain to be determined, we focused on the influence of brain death (BD) on TF and MCP-1 expression in the pancreatic tissues and isolated islets using a rodent model. TF and MCP-1 mRNA levels in the pancreatic tissues were similar between the BD and the control group. However, TF and MCP-1 mRNA in the fresh islets of the BD group were significantly higher than that of the control group (p < 0.01). BD may thus be suggested to be of great importance as an initiator of TF and MCP-1 induction in the isolated islets. Furthermore, the upregulation of crucial inflammatory mediators induced by BD could be exacerbated by warm ischemic damage during digestion procedures. In the present study, the islet yield and purity were affected by BD. However, almost no influences were observed with respect to islet viability, indicating that the expression of inflammatory mediators rather than islet viability is more susceptible to BD. According to the change in time course of TF and MCP-1 expression in the isolated islets, the selected time point for islet infusion in current clinical islet transplantation was thus shown to be at its worst level, at least with respect to the damage caused by BD and ischemic stress. In conclusion, BD in combination with warm ischemic stress during isolation procedures induces a high expression of TF and MCP-1 in the isolated islets. In order to reduce the expression of crucial inflammatory mediators in the islet grafts, the management of the pancreas from brain-dead donors with early anti-inflammatory treatments is thus warranted.

Distinct Cytokine Patterns in Different States of Kidney Allograft Function

Cytokines are crucial inflammatory mediators involved in the development of immune response leading to allograft rejection. We investigated the cytokine patterns in patients sera from cases of acute rejection episodes (ARE), chronic rejection (CR), and long-term stable courses (STABLE). The project included 20 patients with ARE, 20 with CR, and 15 with at least a 5-year stable course. Serum samples collected at the time of rejection diagnosis were cytometrically tested for concentrations of interleukin (IL) 2, IL-4, IL-6, IL-10, interferon (IFN) γ, and tumor necrosis factor α. No significant differences between investigated groups were observed before transplantation ( P > .05). Significant differences were observed among the groups in serum levels of IFN-γ, IL-4, IL-6, and IL-10. Our data suggested that distinct serum cytokine patterns were present among various states of kidney allograft function. ARE was characterized by a mixed cytokine pattern with elevated IL-10 and IFN-γ compared with the STABLE patients. The cytokine pattern in CR patients, in turn, was characterized by elevated levels of IL-4, IL-6, and IL-10 and decreased levels of IFN- γ compared with both STABLE and ARE subjects. Our results suggested that the T H2 response may contribute to the initiation and/or maintenance of CR, because IL-4, IL-6, and IL-10 serve as growth and differentiation factors for B cells to increase antibody production. We also observed up-regulated production of IFN-γ and down-regulation of T H2 cytokines among patients with stable long- term graft function.

Deregulation of cyclooxygenase and nitric oxide synthase gene expression in the inflammatory cascade triggered by experimental group B streptococcal meningitis in the newborn brain and cerebral microvessels

Group B Streptococcus (GBS) is the most common cause of neonatal sepsis and meningitis. Despite antibiotics, GBS in the newborn initiates a cascade of molecular and biological events leading to altered cerebral perfusion, blood-brain barrier disruption, cerebral edema, intracranial hypertension, neurological damage, and even death. Having previously shown that GBS infection impairs cerebral blood flow autoregulation and increases prostaglandin (PG) levels, we examined the regulation of some crucial inflammatory mediators (PGs, nitric oxide (NO), tumor necrosis factor-a) in the brain and cerebral microvessels (MVs) from newborn piglets. Cyclooxygenase (COX), the key enzyme in PG biosynthesis, exists in two isoforms, COX-1 and COX-2. Both may be directly induced by NO in a model of renal inflammation. Besides its neurotransmitter role, NO is a potent vasorelaxant whose production is catalyzed by at least three distinct nitric oxide synthases (NOS) (bNOS, ecNOS, iNOS). Western blot analyses showed that the newborn (4 day old) brain expressed lower levels of COX-1 (8-fold), COX-2 (20-fold), bNOS (12-fold), and ecNOS (5-fold) than in the 1 day old. MV showed approximately equal levels of COX-2, lower levels of COX-1 (4-fold), bNOS (5-fold), and higher levels of ecNOS (20-fold) in comparison to 4-day-old cerebral MV. A 4-day-old brain expressed lower levels of bNOS (5-fold), ecNOS (10-fold), and COX-1 (2-fold) than the 6-week-old pig. COX-2 protein was undetected in a 4-day-old pig brain, but present in great excess in MV. Purified MV showed lower ecNOS (14-fold), COX-1 (2-fold), and about equal levels of bNOS and COX-2 in comparison with MV from 6-week-old pigs. Reverse transcription polymerase chain reaction analyses confirmed these results. Treatment with noo-nitro-L-arginine (LNA), a NOS inhibitor, downregulated COX-1 expression in the newborn brain and both COX-1 and COX-2 cerebral MV expression. GBS infection (10(9) colony-forming units, 0.5 mL intracerebroventricular) of sedated newborn piglets induced the expression of tumor necrosis factor-alpha in the cerebrospinal fluid after 2 hours, upregulated bNOS expression in both brain and MVs, upregulated ecNOS in MVs, and downregulated COX-1, COX-2, and ecNOS in the brain. GBS did not trigger the expression of iNOS. Our data suggest that there is a net deficiency of NOS isoforms in the immature brain and microvasculature of the 4-day-old piglet and that the differences in expression lead to the immature control of NO and PG production, rendering newborns particularly susceptible to neurological damage because of the undeveloped nature of their response mechanisms. Moreover, the GBS-induced cascade deregulates the gene expression of interacting inflammatory mediators and may cause a net vasoconstrictor/vasodilator imbalance, leading to cerebral hypertension and edema in the early stages of infection. Pharmacological manipulations of the inflammatory cascade could lead to novel therapeutic approaches for the treatment of GBS meningitis.