Excessive Secretion Of Pro-inflammatory Cytokines Research Articles

Inhibition of Immunoproteasome Attenuates NLRP3 Inflammasome Response by Regulating E3 Ubiquitin Ligase TRIM31

Excessive secretion of pro-inflammatory cytokines leads to the disruption of intestinal barrier in inflammatory bowel disease (IBD). The inflammatory cytokine tumor necrosis factor alpha (TNFα) induces the assembly of the NLRP3 inflammasome, resulting in the augmented secretion of inflammatory cytokines implicated in the pathogenesis of inflammatory bowel disease (IBD). TNFα has also been known to induce the formation of immunoproteasome (IP), which incorporates immunosubunits LMP2, LMP7, and MECL-1. Inhibition of IP activity using the IP subunit LMP2-specific inhibitor YU102, a peptide epoxyketone, decreased the protein levels of NLRP3 and increased the K48-linked polyubiquitination levels of NLRP3 in TNFα-stimulated intestinal epithelial cells. We observed that inhibition of IP activity caused an increase in the protein level of the ubiquitin E3 ligase, tripartite motif-containing protein 31 (TRIM31). TRIM31 facilitated K48-linked polyubiquitination and proteasomal degradation of NLRP3 with an enhanced interaction between NLRP3 and TRIM31 in intestinal epithelial cells. In addition, IP inhibition using YU102 ameliorated the symptoms of colitis in the model mice inflicted with dextran sodium sulfate (DSS). Administration of YU102 in the DSS-treated colitis model mice caused suppression of the NLRP3 protein levels and accompanied inflammatory cytokine release in the intestinal epithelium. Taken together, we demonstrated that inhibiting IP under inflammatory conditions induces E3 ligase TRIM31-mediated NLRP3 degradation, leading to attenuation of the NLRP3 inflammatory response that triggers disruption of intestinal barrier.

Efferocytosis-Inspired Biomimetic Nanoplatform for Targeted Acute Lung Injury Therapy.

Acute lung injury (ALI) is a serious inflammatory disease that causes impairment of pulmonary function. Phenotypic modulation of macrophage in the lung using fibroblast growth factor 21 (FGF21) may be a potential strategy to alleviate lung inflammation. Consequently, achieving specific delivery of FGF21 to the inflamed lung and subsequent efficient FGF21 internalization by macrophages within the lung becomes critical for effective ALI treatment. Here, an apoptotic cell membrane-coated zirconium-based metal-organic framework UiO-66 is reported for precise pulmonary delivery of FGF21 (ACM@U-FGF21) whose design is inspired by the process of efferocytosis. ACM@U-FGF21 with apoptotic signals is recognized and internalized by phagocytes in the blood and macrophages in the lung, and then the intracellular ACM@U-FGF21 can inhibit the excessive secretion of pro-inflammatory cytokines by these cells to relieve the inflammation. Utilizing the homologous targeting properties inherited from the source cells and the spontaneous recruitment of immune cells to inflammatory sites, ACM@U-FGF21 can accumulate preferentially in the lung after injection. The results prove that ACM@U-FGF21 effectively reduces inflammatory damage to the lung by modulating lung macrophage polarization and suppressing the excessive secretion of pro-inflammatory cytokines by activated immune cells. This study demonstrates the usefulness of efferocytosis-inspired ACM@U-FGF21 in the treatment of ALI.

PROTAC targeting cyclophilin A controls virus-induced cytokine storm

Cytokine storms caused by viruses are associated with elevated cytokine levels and uncontrolled inflammatory responses that can lead to acute respiratory distress syndrome. Current antiviral therapies are not sufficient to prevent or treat these complications. Cyclophilin A (CypA) is a key factor that regulates the production of multiple cytokines and could be a potential therapeutic target for cytokine storms. Here, three proteolysis targeting chimeras (PROTACs) targeting CypA were designed. These PROTACs bind to CypA, enhance its ubiquitination, and promote its degradation in both cell lines and mouse organs. During influenza B virus (IBV) infection, PROTAC-mediated CypA depletion reduces P65 phosphorylation and NF-κB-mediated proinflammatory cytokine production in A549 cells. Moreover, Comp-K targeting CypA suppresses excessive secretion of proinflammatory cytokines in bronchoalveolar lavage fluid, reduces lung injury, and enhances survival rates of IBV-infected mice. Collectively, we provide PROTACs targeting CypA, which are potential candidates for the control of cytokine storms.

ANXA1sp Protects against Sepsis-Induced Myocardial Injury by Inhibiting Ferroptosis-Induced Cardiomyocyte Death via SIRT3-Mediated p53 Deacetylation.

Sepsis-induced myocardial injury (SIMI), a common complication of sepsis, may cause significant mortality. Ferroptosis, a cell death associated with oxidative stress and inflammation, has been identified to be involved in SIMI. This study sought to investigate the role of ANXA1 small peptide (ANXA1sp) in SIMI pathogenesis. In this study, the mouse cardiomyocytes (H9C2 cells) were stimulated with lipopolysaccharide (LPS) to imitate SIMI in vitro. It was shown that ANXA1sp treatment substantially abated LPS-triggered H9C2 cell death and excessive secretion of proinflammatory cytokines (TNF-α, IL-1β, and IL-6). ANXA1sp pretreatment also reversed the increase of ROS and MDA generation as well as the decrease of SOD and GSH activity in H9C2 cells caused by LPS treatment. In addition, ANXA1sp considerably eliminated LPS-caused H9C2 cell ferroptosis, as revealed by the suppression of iron accumulation and the increase in GPX4 and FTH1 expression. Furthermore, the ameliorative effects of ANXA1sp on LPS-induced H9C2 cell damage could be partially abolished by erastin, a ferroptosis agonist. ANXA1sp enhanced SIRT3 expression in LPS-challenged H9C2 cells, thereby promoting p53 deacetylation. SIRT3 knockdown diminished ANXA1sp-mediated alleviation of cell death, inflammation, oxidative stress, and ferroptosis of LPS-treated H9C2 cells. Our study demonstrated that ANXA1sp is protected against LPS-induced cardiomyocyte damage by inhibiting ferroptosis-induced cell death via SIRT3-dependent p53 deacetylation, suggesting that ANXA1sp may be a potent therapeutic agent for SIMI.

Antiviral Molecular Targets of Essential Oils against SARS-CoV-2: A Systematic Review

Essential oils are potential therapeutics for coronavirus disease 2019 (COVID-19), in which some of the volatile compounds of essential oils have been well known for their broad antiviral activities. These therapeutic candidates have been shown to regulate the excessive secretion of pro-inflammatory cytokines, which underlies the pathogenesis of severe COVID-19. We aimed to identify molecular targets of essential oils in disrupting the cell entry and replication of SARS-CoV-2, hence being active as antivirals. Literature searches were performed on PubMed, Scopus, Scillit, and CaPlus/SciFinder (7 December 2022) with a truncated title implying the anti-SARS-CoV-2 activity of essential oil. Data were collected from the eligible studies and described narratively. Quality appraisal was performed on the included studies. A total of eight studies were included in this review; four of which used enzyme inhibition assay, one—pseudo-SARS-CoV-2 culture; two—whole SARS-CoV-2 culture; and one—ACE2-expressing cancer cells. Essential oils may prevent the SARS-CoV-2 infection by targeting its receptors on the cells (ACE2 and TMPRSS2). Menthol, 1,8-cineole, and camphor are among the volatile compounds which serve as potential ACE2 blockers. β-caryophyllene may selectively target the SARS-CoV-2 spike protein and inhibit viral entry. Other interactions with SARS-CoV-2 proteases and RdRp are observed based on molecular docking. In conclusion, essential oils could target proteins related to the SARS-CoV-2 entry and replication. Further studies with improved and uniform study designs should be carried out to optimize essential oils as COVID-19 therapies.

Free-radical oxidation as a pathogenetic factor of metabolic syndrome

The medical and social significance of cardiovascular diseases remains high. One of the factors that determine cardiovascular risks is metabolic syndrome. As a result of excessive accumulation of lipid and carbohydrate metabolism products in metabolic syndrome, oxidative (oxidative) stress develops. The article considers both domestic and foreign scientific studies, which highlight various aspects of the influence of reactive oxygen and nitrogen species, as well as other free radicals on the formation of oxidative stress in pathological conditions that are part of the metabolic syndrome complex. This describes the mechanisms of the formation of chronic inflammation through excessive secretion of pro-inflammatory cytokines and adipokines, activation of the transcription factor NF-kB, as well as damage to the antioxidant system in obesity. Separately, a number of mechanisms of the stimulating effect of adipokines: leptin, adiponectin, chimerine, omentin 1, resistin, on the formation of oxidative stress have been noted. The ways of activating the polyol pathway, as well as diacyl-glycerol — protein kinase C — the signaling pathway of oxidative stress, the formation of mitochondrial dysfunction is described. As a result of which there is an excessive production of free radicals in insulin resistance, diabetes mellitus and macroand microvascular complications of diabetes. In addition, the influence of oxidative stress directly on the formation of cardiovascular diseases of atherosclerotic genesis, as well as arterial hypertension, has been shown.

ПОГЛЯДНАПАТОГЕНЕТИЧНІМЕХАНІЗМИУРАЖЕННЯСУГЛОБІВПРИКОРОНАВІРУСНІЙХВОРОБІ 2019 (COVID-19)

The Сoronavirus disease 2019 (COVID-19) pandemic has had an extremely serious impact on the livelihoods of people worldwide. Despite the mainly respiratory manifestations of SARS-CoV-2 infection, its consequences can affect the functioning of most systems of organism, including the musculoskeletal, dysfunction of which is a leading factor in disability of the population. Diseases of the joints are one of the most common pathologie of modernity, which in the last decade are increasingly found in young people and even children. The musculoskeletal symptoms can be observed as isolated clinical signs and expressed regardless of the severity of the viral disease. Chronic fatigue, myalgia, swelling and joint pain may occur during the acute phase of COVID-19 and as short-term or long-term complications, but their prevalence has not been systematically studied. Considering the wide range of clinical manifestations of SARS-CoV-2 infection and the complexity of their pathogenesis, the mechanisms underlying lesions of musculoskeletal system and rheumatological complications remain unclear. Today, the main research in this direction is focused mainly on a complete understanding of the regulatory pathways of immune dysregulation and inflammation. Excessive secretion of pro-inflammatory cytokines, disruption of signal transduction and immune response are the result of the severe impact of SARS-CoV-2 infection on most organs, including joints, as well as the use of corticosteroids for the treatment of patients with COVID-19. The presented review highlights generalized information on the main pathophysiological processes that can occur in the joints as a manifestation of the impact of SARS-CoV-2 infection, and possible key mechanisms which contribute to the progression of pathological changes.

Glycogen Synthase Kinase-3: A Focal Point for Advancing Pathogenic Inflammation in Depression.

Increasing evidence indicates that the host immune response has a monumental role in the etiology of major depressive disorder (MDD), motivating the development of the inflammatory hypothesis of depression. Central to the involvement of chronic inflammation in MDD is a wide range of signaling deficits induced by the excessive secretion of pro-inflammatory cytokines and imbalanced T cell differentiation. Such signaling deficits include the glutamatergic, cholinergic, insulin, and neurotrophin systems, which work in concert to initiate and advance the neuropathology. Fundamental to the communication between such systems is the protein kinase glycogen synthase kinase-3 (GSK-3), a multifaceted protein critically linked to the etiology of MDD and an emerging target to treat pathogenic inflammation. Here, a consolidated overview of the widespread multi-system involvement of GSK-3 in contributing to the neuropathology of MDD will be discussed, with the feed-forward mechanistic links between all major neuronal signaling pathways highlighted.

Lipoprotein Lipase Regulates Microglial Lipid Droplet Accumulation.

Microglia become increasingly dysfunctional with aging and contribute to the onset of neurodegenerative disease (NDs) through defective phagocytosis, attenuated cholesterol efflux, and excessive secretion of pro-inflammatory cytokines. Dysfunctional microglia also accumulate lipid droplets (LDs); however, the mechanism underlying increased LD load is unknown. We have previously shown that microglia lacking lipoprotein lipase (LPL KD) are polarized to a pro-inflammatory state and have impaired lipid uptake and reduced fatty acid oxidation (FAO). Here, we also show that LPL KD microglia show excessive accumulation of LD-like structures. Moreover, LPL KD microglia display a pro-inflammatory lipidomic profile, increased cholesterol ester (CE) content, and reduced cholesterol efflux at baseline. We also show reduced expression of genes within the canonical cholesterol efflux pathway. Importantly, PPAR agonists (rosiglitazone and bezafibrate) rescued the LD-associated phenotype in LPL KD microglia. These data suggest that microglial-LPL is associated with lipid uptake, which may drive PPAR signaling and cholesterol efflux to prevent inflammatory lipid distribution and LD accumulation. Moreover, PPAR agonists can reverse LD accumulation, and therefore may be beneficial in aging and in the treatment of NDs.

Obesity, inflammation and COVID-19: preventive interest of ketogenic diet?

Obesity is considered a pandemic responsible for millions of deaths worldwide for many years. At the end of 2019, the Coronavirus disease 2019 (COVID-19) appeared, causing the death of more than a million people in less than a year. Numerous studies suggest that obesity could be defined as key to the onset of severe forms of this emerging disease. Indeed, SARS-CoV2 infects the host by binding to ACE2 receptors present on the surface of the cells and causes excessive secretion of pro-inflammatory cytokines including IL-1, IL-6 and TNF-α, which lead to developing acute respiratory distress syndrome (ARDS). It therefore seems essential to make up effective preventive strategies to protect this part of the population from the risk of developing a severe form of COVID-19. The ketogenic diet, which is low in sugars and high in fat, has interesting properties, both in the fight against obesity but also against severe infections. This article focuses on the latest scientific advances that make it possible to consider the ketogenic diet as a preventive strategy that simultaneously reduces the development of obesity while strengthening the immune system, two key actions in the fight against SARS-CoV2 infections and severe forms of COVID-19.

Injecting Immunosuppressive M2 Macrophages Alleviates the Symptoms of Periodontitis in Mice.

Periodontitis is the second most common oral disease affecting tooth-supporting structures. The tissue damage is mainly initiated by the excessive secretion of proinflammatory cytokines by immune cells. Macrophages are a type of antigen-presenting cells that influence the adaptive immunity function. We used a unique set of cytokines, i.e., a combination of IL-4, IL-13, and IL-10, to stimulate macrophages into a subset of M2 polarization cells that express much higher levels of ARG-1, CD206, and PDL-2 genes. The cells’ anti-inflammatory potential was tested with mixed-lymphocyte reaction assay, which showed that this subset of macrophages could increase IL-2 secretion and suppress IL-17, IL-6, and TNF-α secretion by splenocytes. The gram-negative bacterial species Porphyromonas gingivalis was used to initiate an inflammatory process in murine periodontal tissues. In the meantime, cell injection therapy was used to dampen the excessive immune reaction and suppress osteoclast differentiation during periodontitis. Maxilla was collected and analyzed for osteoclast formation. The results indicated that mice in the cell injection group exhibited less osteoclast activity within the periodontal ligament region than in the periodontitis group. Moreover, the injection of M2 macrophages sustained the regulatory population ratio. Therefore, the M2 macrophages induced under the stimulation of IL-4, IL-13, and IL-10 combined had tremendous immune modulation ability. Injecting these cells into local periodontal tissue could effectively alleviate the symptom of periodontitis.

Abstract PO-051: Intracellular delivery of nuclear localization signal suppresses COVID-19 mediated inflammation by regulating expression of cytokines/chemokines

Abstract The outbreak of coronavirus disease 19 (COVID-19), caused by the recently identified coronavirus named SARS-CoV-2, is leading patients to death (mortality: ~7%) because of cytokine storm. COVID-19 induces excessive secretion of proinflammatory cytokines and chemokines accompanied by the disruption of the bronchi and alveoli, which could ultimately develop into permanent lung impairments such as pulmonary fibrosis. To regulate the uncontrolled expression of proinflammatory cytokines/chemokines, improved cell-permeable nuclear import inhibitor (iCP-NI) has been developed by fusing sequence-optimized hydrophobic cell-penetrating peptide (CPP), namely advanced macromolecule transduction domain (aMTD) with nuclear localization signal (NLS) of stress responsive transcription factors (SRTFs: NF-κB, STAT1/3, AP-1, and NFAT). Intracellularly delivered NLS is supposed to suppress expression of proinflammatory cytokines/chemokines by inhibiting transport of SRTFs from cytoplasm into nucleus. iCP-NI regulated expression of cytokines (TNF-α: -79%, IL-6: -91%, IL-12: -110% and IL-10: +574%) and chemokines (MCP-1: -89%) in bronchoalveolar lavage fluids (BALFs) from RNA virus infection mimetic pneumonitis animals that were induced with inhalation of RNA structure molecule, poly I:C. iCP-NI also significantly decreased pulmonary fibrosis (-61%) in bleomycin-induced pulmonary fibrosis animals. Moreover, iCP-NI protected leukocytes (CD3+ T cell: 100%, CD4+/CD3+ T cell: 96%, B220+ B cell: 85%, CD45+ macrophage: 100%) and reduced apoptotic splenocytes (-97%) in staphylococcal enterotoxin B (SEB) and poly I:C-induced acute pneumonitis animals. These results suggest that iCP-NI has potential as a novel therapeutic measurement for inflammation caused by various infectious diseases including COVID-19 accompanied with cytokine storm and severe sepsis. Citation Format: Danbi Lee, Sanghyeon Yu, Misuk Baek, Jieun Kim, Mingu Kang, Hakyoung Park, Jaewook Lee, Seokwon Lee, Junghun Kwak, Hyemin Yu, Seungwoo Lee, Sujeong Kim, Hyewon Lee, Dasom Shin, Boram Kim, Minyoung Jung, Youngsil Choi, Daewoong Jo, Gyunam Kim, Dongho Kim. Intracellular delivery of nuclear localization signal suppresses COVID-19 mediated inflammation by regulating expression of cytokines/chemokines [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2020 Jul 20-22. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(18_Suppl):Abstract nr PO-051.

Immunomodulatory Effect of Doxycycline Ameliorates Systemic and Pulmonary Inflammation in a Murine Polymicrobial Sepsis Model.

Acute lung injury is an inflammatory condition developed after severe sepsis in response to excessive secretion of pro-inflammatory cytokines. Doxycycline is widely reported to possess immunomodulatory activity through inhibition of various inflammatory pathways. Considering the broad spectrum of anti-inflammatory activity, protective effect of doxycycline was evaluated in clinically relevant murine polymicrobial sepsis model induced by caecal ligation and puncture (CLP). In this model, sepsis is accompanied with infection and therefore ceftriaxone at sub-protective dose was combined to retard the bacterial growth. Three hours after CLP challenge, mice were administered vehicle, ceftriaxone (100 mg/kg subcutaneously) alone and in combination with immunomodulatory dose of doxycycline (50 mg/kg, intraperitoneal) and survival were monitored for 5 days. Bacterial count in blood and peritoneal fluid along with cytokines [interleukin (IL)-6, IL-1β, tumour necrosis factor (TNF)-α] and myeloperoxidase (MPO) in plasma and lung homogenate were measured at 18 h post-CLP. Plasma glutathione (GSH) was also determined. Doxycycline in presence of ceftriaxone improved survival of septic mice by significantly reducing the plasma and lung pro-inflammatory cytokines and MPO levels. It also increased plasma GSH levels. Doxycycline did not improve antibacterial effect of ceftriaxone in combination, suggesting that the protective effect of doxycycline was due to its immunomodulatory activity. Doxycycline in the presence of ceftriaxone demonstrated improved survival of septic mice by modulating the immune response.

Myrtus Polyphenols, from Antioxidants to Anti-Inflammatory Molecules: Exploring a Network Involving Cytochromes P450 and Vitamin D.

Inflammatory response represents one of the main mechanisms of healing and tissue function restoration. On the other hand, chronic inflammation leads to excessive secretion of pro-inflammatory cytokines involved in the onset of several diseases. Oxidative stress condition may contribute in worsening inflammatory state fall, increasing reactive oxygen species (ROS) production and cytokines release. Polyphenols can counteract inflammation and oxidative stress, modulating the release of toxic molecules and interacting with physiological defenses, such as cytochromes p450 enzymes. In this paper, we aimed at evaluating the anti-inflammatory properties of different concentrations of Myrtus communis L. pulp and seeds extracts, derived from liquor industrial production, on human fibroblasts. We determined ROS production after oxidative stress induction by H2O2 treatment, and the gene expression of different proinflammatory cytokines. We also analyzed the expression of CYP3A4 and CYP27B1 genes, in order to evaluate the capability of Myrtus polyphenols to influence the metabolic regulation of other molecules, including drugs, ROS, and vitamin D. Our results showed that Myrtus extracts exert a synergic effect with vitamin D in reducing inflammation and ROS production, protecting cells from oxidative stress damages. Moreover, the extracts modulate CYPs expression, preventing chronic inflammation and suggesting their use in development of new therapeutic formulations.

Role of microRNAs in sepsis.

MicroRNAs have been found to be of high significance in the regulation of various genes and processes in the body. Sepsis is a serious clinical problem which arises due to the excessive host inflammatory response to infection. The non-specific clinical features and delayed diagnosis of sepsis has been a matter of concern for long time. MicroRNAs could enable better diagnosis of sepsis and help in the identification of the various stages of sepsis. Improved diagnosis may enable quicker and more effective treatment measures. The initial acute and transient phase of sepsis involves excessive secretion of pro-inflammatory cytokines which causes severe damage. MicroRNAs negatively regulate the toll-like receptor signaling pathway and regulate the production of inflammatory cytokines during sepsis. Likewise, microRNAs have shown to regulate the vascular barrier and endothelial function in sepsis. They are also involved in the regulation of the apoptosis, immunosuppression, and organ dysfunction in later stages of sepsis. Their importance at various levels of the pathophysiology of sepsis has been discussed along with the challenges and future perspectives. MicroRNAs could be key players in the diagnosis and staging of sepsis. Their regulation at various stages of sepsis suggests that they may have an important role in altering the outcome associated with sepsis.

Attenuated Blood-Brain Barrier Dysfunction by XQ-1H Following Ischemic Stroke in Hyperlipidemic Rats.

Following ischemic stroke, blood-brain barrier (BBB) is disrupted and is further aggravated with the corresponding incidence of hyperlipidemia. BBB breakdown promotes inflammation infiltration into the brain, which exacerbates cerebral ischemic injury as a result. Here, we report that 10-O-(N,N-dimethylaminoethyl)-ginkgolide B methanesulfonate (XQ-1H), a novel analog of ginkgolide B, alleviates BBB breakdown in hyperlipidemic rats and protects endothelial cells against inflammatory response. Middle cerebral artery occlusion (MCAO) modeled ischemic stroke in rats. Before surgery, these rats were fed a cholesterol-rich diet to induce an experimental hyperlipidemic condition. Additionally, lipopolysaccharide (LPS) incubation with rat brain microvessel endothelial cells (rBMECs) was applied to mimic hyperlipidemia-induced inflammatory injury of BBB. The results indicated more severe infarct size, increased BBB permeability, excessive secretion of pro-inflammatory cytokines, and exaggerated inflammation infiltration of the brain in hyperlipidemic rats following MCAO when compared to rats fed with normal diet. XQ-1H protected BBB integrity, lessoned brain edema and inflammation penetration, downregulated MMP-9 and VCMA-1 expressions, and extenuated ischemic infarction. XQ-1H alleviated LPS-induced inflammatory response in rBMECs, characterized by promoting cell viability, inhibiting TNF-α, IL-1β, and IL-6 releasing, and downregulating NF-κB inflammatory signal and downstream proteins, such as VCAM-1 and iNOS. In conclusion, the present study shows that XQ-1H stabilizes BBB function following ischemic stroke in hyperlipidemic rats, and the possible mechanisms may be related to inflammation inhibition.

Gambogic acid and celastrol are two powerful anti-inflammatory drugs in arthritis

BackgroundRheumatoid arthritis (RA) is a chronic inflammatory disease where the excessive secretion of pro-inflammatory cytokines plays an important role. The authors have previously reported an increase in circulating interleukin 1β...

Polydopamine coatings enhance biointegration of a model polymeric implant

The biointegration of implants affects their function, stability and safety. Although most research on this topic has focused on bone and other hard tissues, biointegration with soft tissues is important in numerous applications, such as in prosthetic corneas. Here, we have adapted polydopamine-based adhesive surface chemistry to enhance the biointegration with soft tissue of a model polymer—poly(methyl methacrylate) (PMMA), commonly used in prosthetic corneas. Polydopamine coating (PDA) and subsequent modification with the cell-adhesive peptide RGD (PDA-PEG-RGD) significantly enhanced cellular proliferation of corneal epithelial cells and keratocytes without causing excessive secretion of pro-inflammatory cytokines (e.g.IL-6) by either cell type. PDA adhered tightly to collagen gels, while PDA-PEG-RGD and uncoated PMMA did not. PDA's adhesion to collagen was greatly reduced by preincubation in serum. Tissue reaction to both polydopamine-coated surfaces was benign after 45 days of subcutaneous implantation. However, in contrast to the findings with collagen gels, PDA-PEG-RGD bound much more tightly to tissue than did PDA—although both bound better than unmodified PMMA. Polydopamine-based surface chemistries are potentially useful in enhancing tissue integration of implants with soft tissues.

Downregulation of Proinflammatory Cytokine Release in Whole Blood From Septic Patients

Using animal models or healthy volunteers, injection of lipopolysaccharide (LPS) or bacteria causes activation of macrophages with excessive synthesis and secretion of proinflammatory cytokines. Although these models mimic the effects of LPS in the host, they may represent more of an experimental expression of endotoxemia than natural infection itself. Therefore, as an ex vivo model of sepsis, whole blood from 15 patients with severe sepsis and 20 control patients without infection was stimulated with LPS to study the kinetics of mRNA expression and release of proinflammatory cytokines, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, and IL-6. Stimulation of whole blood with 1 microgram/mL LPS resulted in a maximum increase of cytokine secretion in the control group, while a marked (P < .01) depression of TNF-alpha, IL-1 beta, and IL-6 release was observed in the septic group, which persisted up to 10 days after study enrollment. While IL-1 beta mRNA expression was similar in peripheral blood mononuclear cells (PBMCs) harvested from LPS-stimulated whole blood in septic and control patients, the half-life and consequently the expression of TNF-alpha and IL-6 mRNA were strongly reduced in the septic group. These data indicate a downregulatory mechanism of cytokine release in whole blood from patients with severe sepsis that occurs on different levels. Although excessive secretion of proinflammatory cytokines has been considered deleterious for the host, the reduced capacity of PBMCs in whole blood from septic patients to synthesize and secrete proinflammatory cytokines to an inflammatory stimulus may result in immunodeficiency, because these cytokines in low concentrations are involved in the upregulation of essential cellular and humoral immune functions.