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Inflammation: cause of vascular disease and malnutrition in dialysis patients.

Inflammation occurs in response to tissue injury or the presence of foreign antigens and is important in the mobilization of specific immunologic and nonimmunologic defenses against injury. The vascular endothelium is altered to allow immune competent cells to access the interstitial space. Muscle and visceral proteins are catabolized and the amino acids are used either to supply energy or as substrates for the production of acute-phase proteins that play a role in defense. Restoration of muscle mass is impaired while inflammation is on going. Lipids are mobilized. Although serving a vital role in allowing host survival from acute injury or infection, if unimpeded, or if triggered inappropriately, the acute-phase response may instead lead to increased vascular injury and progressive loss of muscle and visceral protein pools causing malnutrition. Markers of inflammation (C reactive protein [CRP] or interleukin-6 [IL-6] levels) are associated with cardiovascular risk in the general population and in dialysis patients. Hypoalbuminemia also is associated with cardiovascular risk in dialysis patients. Although albumin is considered a marker of nutrition, changes in albumin levels are associated with increased levels of acute-phase proteins. Persistent changes in albumin levels are caused by reduced albumin synthesis associated with inflammation and not decreased normalized protein catabolic rate. The cause(s) of inflammation must be identified and treated to resolve malnutrition and reduce cardiovascular risk.

Humans↗

Two-way interactions between inflammation and coagulation.

Activation of inflammatory and coagulation pathways is important in the pathogenesis of vascular disease. There is ample evidence that extensive cross-talk between these two systems exists, whereby inflammation not only leads to activation of coagulation, but coagulation also markedly affects inflammatory activity. The main interfaces linking coagulation and inflammation are the tissue factor pathway, thrombin, the protein C system and the fibrinolytic (or plasminogen-plasmin) system. Proinflammatory cytokines and chemokines can affect all these coagulation mechanisms, and vice versa, activated coagulation proteases and physiological anticoagulants or components of the plasminogen-plasmin system can modulate inflammation by specific cell receptors. The intricate relationship between inflammation and coagulation may not only be relevant for vascular thrombotic disease but also has major consequences in the pathogenesis of microvascular failure and subsequent multiple organ failure in the setting of severe infection. This review focuses on the present understanding of the bidirectional relationship between inflammation and coagulation.

Antigens↗

Detection of acute inflammation with 111In-labeled nonspecific polyclonal IgG.

The detection of focal sites of inflammation is an integral part of the clinical evaluation of the febrile patient. When anatomically distinct abscesses are present, lesion detection can be accomplished by standard radiographic techniques, particularly in patients with normal anatomy. At the phlegmon stage, however, and in patients who have undergone surgery, these techniques are considerably less effective. While radionuclide methods, such as Gallium-67 (67Ga)-citrate and Indium-111 (111In)-labeled WBCs have been relatively successful for the detection of early inflammation, neither approach is ideal. In the course of studies addressing the use of specific organism-directed antibodies for imaging experimental infections in animals, we observed that nonspecific polyclonal immunoglobulin G (IgG) localized as well as specific antibodies. Preliminary experiments suggested that the Fc portion of IgG is necessary for effective inflammation localization. Since polyclonal IgG in gram quantities has been safely used for therapy in patients with immune deficiency states, we decided to test whether milligram quantities of radiolabeled IgG could image focal sites of inflammation in humans. Thus far, we have studied a series of 84 patients with suspected lesions in the abdomen, pelvis, vascular grafts, lungs, or bones/joints. In 48 of 52 patients with focal lesions detected by surgery, computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound (US), the IgG scan correctly localized the site, while 31 patients without focal inflammation had no abnormal focal localization of the radiopharmaceutical. Four patients had false negative scans and one patient had a false positive scan. For this small series, the overall sensitivity and specificity were 92% and 95%, respectively. In this report, we review our experience with this exciting new agent.

Acute Disease↗

Effects of statins on inflammation in patients with acute and chronic coronary syndromes.

Inflammation plays a crucial role in the cell biology of atherosclerosis. Coronary risk factors, and particularly low-density lipoprotein (LDL) cholesterol, injure the endothelium and decrease the bioavailability of nitric oxide to promote the expression of proinflammatory genes, cellular adhesion molecules, cytokines, chemokines, and growth factors. For example, the expression of CD40/CD40 ligand increases cell-mediated immune responses to activate a number of inflammatory cells and destabilize atherosclerosis. As part of this response, soluble markers of inflammation that are released into the blood offer insights into the cell biology of inflammation in atherosclerosis. In groups of patients, these markers have provided a means to study inflammatory mechanisms and have supported the value of many of our interventions that prevent cardiovascular disease. Statins have potent effects to reduce LDL cholesterol in the plasma and the artery wall and also appear to have a number of nonlipid effects that decrease inflammatory stimuli. Because statins also reduce some soluble markers of inflammation, it is likely that at least part of their benefit reflects a reduction in vascular inflammation in stable and unstable coronary syndromes. Although these inflammatory markers are valuable tools for studying the mechanisms of atherosclerosis, their use in clinical practice to stratify cardiovascular risk or assess treatment in individual patients requires further evaluation.

Acute Disease↗

Association between airway bacterial load and markers of airway inflammation in patients with stable chronic bronchitis.

PURPOSE: Viable bacteria are often isolated from airway secretions in clinically stable patients with chronic bronchitis. We hypothesized that the number of organisms and bacterial species might be important modulators of airway inflammation. SUBJECTS AND METHODS: We performed quantitative sputum cultures in 160 stable patients [55 with chronic obstructive pulmonary disease (COPD) and normal serum alpha(1)-antitrypsin levels, 62 with COPD and severe alpha(1)-antitrypsin deficiency (PiZ), and 43 with idiopathic bronchiectasis]. The results were related to several indicators of the mechanisms and severity of airway inflammation. RESULTS: Airway bacterial load correlated with sputum myeloperoxidase level, an indirect measure of neutrophil activation and number (r = 0.50, P<0. 001); sputum neutrophil chemoattractants [interleukin-8 level (r = 0. 68, P<0.001) and leukotriene B4 level (r = 0.53, P<0.001)]; sputum leukocyte elastase activity (r = 0.55, P<0.001); and albumin leakage from serum to sputum (r = 0.26, P<0.01). Markers of inflammation increased at bacterial loads of 10(6) to 10(7) colony-forming units per milliliter, and increased progressively with increasing bacterial load. For example, the median (interquartile range) sputum myeloperoxidase level was 0.3 U/mL (0.1 to 0.5 U/mL) for patients who were not colonized or who had mixed normal oropharyngeal flora alone; 0.5 U/mL (0.2 to 0.7 U/mL) for patients with 10(5) to 10(6) colony-forming units per milliliter (P = 0.07); 0.5 U/mL (0.3 to 1.2 U/mL) for patients with 10(6) to 10(7) colony-forming units per milliliter (P<0.01); 0.7 U/mL (0.3 to 1.2 U/mL) for patients with 10(7) to 10(8) colony-forming units per milliliter (P <0.005); and 2.4 U/mL (0.7 to 4.8 U/mL) for patients with 10(8) or greater colony-forming units per milliliter (P<0.0001). The bacterial species influenced airway inflammation; for example, sputum myeloperoxidase activity was greater (P<0.005) in patients colonized with Pseudomonas aeruginosa [median 32 U/mL (interquartile range, 20 to 65 U/mL)] than those colonized with nontypeable Hemophilus influenzae [4 U/mL (2 to 31 U/mL)], which in turn was greater (P = 0.01) than among those colonized with Moraxella catarrhalis [1.1 U/mL (0.6 to 1.8 U/mL)]. We did not find a relation between bacterial load and lung function. CONCLUSIONS: The bacterial load and species contribute to airway inflammation in patients with stable chronic bronchitis. Further studies are required to determine the consequences of bacterial colonization on patient morbidity and decline in lung function.

Aged↗

Vascular adhesion protein-1 is involved in both acute and chronic inflammation in the mouse.

Vascular adhesion protein-1 (VAP-1) is an endothelial molecule that possesses both adhesive and enzymatic properties in vitro. So far, however, elucidation of its in vivo function has suffered from the lack of function-blocking reagents that are suitable for use in animal models. In this work we produced monoclonal antibodies against murine VAP-1 and characterized them using in vitro binding assays. We then examined whether the antibodies could prevent leukocyte migration in in vivo inflammation models, including two acute models (peritonitis induced with proteose peptone and interleukin-1 and air pouch inflammation enhanced by CCL21) and one chronic model (autoimmune diabetes in nonobese diabetic mice). Antibodies 7-88 and 7-106 inhibited migration of granulocytes and monocytes in both acute models of inflammation. Strikingly, antibody 7-88 significantly prevented diabetes in a subset of nonobese diabetic mice. The results show for the first time that in mouse models of inflammation, VAP-1 mediates leukocyte trafficking to sites of inflammation and thus is a potential target for anti-inflammatory therapies.

Acute Disease↗

Role of activatory Fc gamma RI and Fc gamma RIII and inhibitory Fc gamma RII in inflammation and cartilage destruction during experimental antigen-induced arthritis.

IgG-containing immune complexes, which are found in most RA joints, communicate with hematopoietic cells using three classes of Fc receptors(Fc gamma RI, -II, -III). In a previous study we found that if a chronic T-cell-mediated antigen-induced arthritis (AIA) was elicited in knee joints of FcR gamma-chain-deficient mice that lack functional Fc gamma RI and Fc gamma RIII, joint inflammation was comparable but severe cartilage destruction was absent. We now examined the individual role of the stimulatory Fc gamma RI and Fc gamma RIII and inhibitory Fc gamma RII in inflammation and functional cartilage damage in knee joints with AIA using Fc gamma RI-, Fc gamma RII-, and Fc gamma RIII-deficient mice. Three weeks after immunization with the antigen-methylated bovine serum albumin (BSA), cellular (T-cell responses as measured by lymphocyte proliferation) immunity raised against mBSA was comparable in all groups examined. Humoral (total IgG, IgG1, IgG2a, and IgG2b levels) immunity against mBSA was comparable in Fc gamma RI-/- and Fc gamma RIII-/- but higher in Fc gamma RII-/- if compared to controls. Joint swelling as measured by (99m)Tc uptake at days 1, 3, and 7 was similar in Fc gamma RI-/- and Fc gamma RIII-/- mice and significantly higher in Fc gamma RII-/-. Chronic inflammation and cartilage damage (depletion of proteoglycans, metalloproteinase (MMP)-induced neoepitopes, and matrix erosion) was studied histologically in total knee joint sections stained with hematoxylin or safranin-O. Histologically, at day 7 after AIA induction, exudate and infiltrate in the knee joint was similar in Fc gamma RI-/- and Fc gamma RIII-/- and significantly higher (230% and 340%) in Fc gamma RII-/- mice if compared to controls. Aggrecan breakdown in cartilage caused by MMPs and, which is related to severe irreversible cartilage erosion, was further studied by immunolocalization of MMP-mediated neoepitopes (VDIPEN) and image analysis. MMP-induced neoepitopes determined in various cartilage layers (tibia and femur) were primarily inhibited in Fc gamma RI-/- (79 to 87% and 87 to 88%, respectively) and comparable in Fc gamma RIII-/-. VDIPEN neoepitopes were much higher (82 to 122% and 200 to 250%, respectively) in Fc gamma RII-/- mice. Initial depletion of proteoglycans was similar (60 to 100%) in all groups. In the chronic phase, cartilage matrix erosion in the lateral and medial tibia was significantly elevated in Fc gamma RII-/- (222% and 186%, respectively) but not in Fc gamma RI-/- or Fc gamma RIII-/- mice. These results suggest that during T-cell-mediated AIA, Fc gamma RI and Fc gamma RIII act in concert in acute and chronic inflammation whereas Fc gamma RI is the dominant FcR involved in severe cartilage destruction. Fc gamma RII is a crucial inhibiting factor in acute and chronic inflammation and cartilage erosion.

Amino Acid Sequence↗

The tyrosine kinase inhibitor tyrphostin AG126 reduces the development of acute and chronic inflammation.

Protein tyrosine kinases help to regulate the expression of many genes that play important roles in inflammation. Here we investigate the effects of the tyrosine kinase inhibitor tyrphostin AG126 in two animal models of acute and chronic inflammation, carrageenan-induced pleurisy and collagen-induced arthritis. We report here that tyrphostin AG126 (given at 1, 3, or 10 mg/kg i.p. in the pleurisy model or 5 mg/kg i.p. every 48 hours in the arthritis model) exerts potent anti-inflammatory effects in animal models of acute and chronic inflammation in vivo. These include the inhibition of pleural exudate formation and mononuclear cell infiltration (pleurisy model) and the development of clinical signs and tissue injury (arthritis model). Furthermore, tyrphostin AG126 reduced the staining for nitrotyrosine and poly (ADP-ribose) polymerase (by immunohistochemistry) and the expression of inducible nitric oxide synthase and cyclooxygenase-2 in the lungs of carrageenan-treated rats and in the joints from collagen-treated rats. Thus, we provide the first evidence that prevention of the activation of protein tyrosine kinases reduces the development of acute and chronic inflammation, and that inhibition of the activity of certain tyrosine kinases may represent a novel approach for the therapy of inflammation.

Acute Disease↗

Noninvasive diagnostic tool for inflammation-induced oxidative stress using electron spin resonance spectroscopy and an extracellular cyclic hydroxylamine.

Inflammation is one of the leading causes of the many pathological states associated with oxidative stress. A crucial role in the development of inflammation-induced oxidative stress is played by reactive oxidant species (ROS), which are very difficult to detect in vivo. One of the most sensitive and definitive methods in the detection of ROS is electron spin resonance, especially as used in conjunction with spin trapping. Unfortunately, the commonly used nitrone spin traps have a very low efficacy for trapping superoxide radicals, and their radical adducts are not stable. To address this deficiency, we have developed negatively charged cyclic hydroxylamines such as 1-hydroxy-4-phosphonooxy-2,2,6,6-tetramethylpiperidine (PP-H) for the detection of reactive oxidant species as a diagnostic tool for extracellular inflammation-induced oxidative stress. We used inflammation induced by a bacterial endotoxin lipopolysaccharide (LPS) as a model. ROS formation was tested in cultured macrophages, in blood and in vivo. PP-H reacts with reactive oxidant species generating the stable nitroxide radical 4-phosphonooxy-TEMPO. It was shown that a 5-h treatment of macrophages with LPS (1 microg/ml) leads to a threefold increase in superoxide formation as demonstrated using superoxide dismutase. Formation of reactive oxidant species 5 h after LPS (1 mg/kg) treatment of Fischer rats was analyzed in arterial blood; formation of reactive oxidant species in LPS-treated animals increased by a factor of 2.2 and was dependent upon the LPS dose. Diphenyleneiodonium (0.1 mM) inhibited formation of LPS-stimulated reactive oxidant species by 80%. We suggest that this test could be used as a noninvasive diagnostic tool for inflammation-induced oxidative stress.

Animals↗

Brain-IL-1beta induces local inflammation but systemic anti-inflammatory response through stimulation of both hypothalamic-pituitary-adrenal axis and sympathetic nervous system.

It is well established that systemic inflammation induces a counter-regulatory anti-inflammatory response particularly resulting in deactivation of monocytes/macrophages. However, recently we demonstrated a systemic anti-inflammatory response without preceding signs of systemic inflammation in patients with brain injury/surgery and release of cytokines into the cerebrospinal fluid (CSF). In order to analyze the mechanisms and pathways of systemic immunodepression resulting from sterile cerebral inflammation we established an animal model using continuous intra-cerebroventricular (i.c.v.) or intra-hypothalamic (i.h.) infusion of rat recombinant (rr) tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta for 48 h. Controls received intra-venous (i.v.) cytokine administration. Interestingly, i.c.v. and i.h. infusion of IL-1beta but not TNF-alpha produced distinct signs of central nervous system (CNS) inflammation. Correspondingly, i.c.v. infusion of IL-1beta particularly diminished the TNF-alpha but increased the IL-10 concentration in whole blood cultures after endotoxin stimulation. All parameters normalized within 48 h after termination of the infusion. Blocking the hypothalamic-pituitary-adrenal (HPA) axis by hypophysectomy (HPX) led to complete recovery of the diminished TNF-alpha concentration and temporarily inhibited the IL-10 increase. Blocking the sympathetic nervous system (SNS) transmission by application of the beta2-adrenoreceptor antagonist propranolol not only inhibited the increase but further downregulated the endotoxin induced IL-10 concentration in the media of whole blood cell cultures, whereas the TNF-alpha decrease was only partially prevented. Interestingly, HPX and propranolol also diminished the cell invasion into the CSF. In summary, activation of both the HPA axis and the SNS plays an important role in systemic anti-inflammatory response resulting from cytokines in brain and cerebral inflammation.

Animals↗

Infection and inflammation and the coagulation system.

Severe infection and inflammation almost invariably lead to hemostatic abnormalities, ranging from insignificant laboratory changes to severe disseminated intravascular coagulation (DIC). Systemic inflammation results in activation of coagulation, due to tissue factor-mediated thrombin generation, downregulation of physiological anticoagulant mechanisms, and inhibition of fibrinolysis. Pro-inflammatory cytokines play a central role in the differential effects on the coagulation and fibrinolysis pathways. Vice-versa, activation of the coagulation system may importantly affect inflammatory responses by direct and indirect mechanisms. Apart from the general coagulation response to inflammation associated with severe infection, specific infections may cause distinct features, such as hemorrhagic fever or thrombotic microangiopathy. The relevance of the cross-talk between inflammation and coagulation is underlined by the promising results in the treatment of severe systemic infection with modulators of coagulation and inflammation.

Antithrombins↗

Possible participation of cyclooxygenase-2 in the recurrence of allergic inflammation in rats.

In the recurrence of allergic inflammation in a rat air pouch model, pouch fluid volume, prostaglandin E2 concentration in the pouch fluid, leukocyte infiltration into the pouch fluid, and granulation tissue weight were markedly increased by the antigen challenge. To clarify the role of cyclooxygenase-2 in the recurrence of allergic inflammation, the time-course of changes in protein levels of cyclooxygenase-1 and cyclooxygenase-2 in the granulation tissue and in the infiltrated leukocytes was examined by Western blot analysis. It was shown that cyclooxygenase-1 levels in the granulation tissue and in the infiltrated leukocytes were not changed by the antigen challenge, but cyclooxygenase-2 levels were increased. Furthermore, treatment with the selective cyclooxygenase-2 inhibitor, NS-398 ([N-2(cyclohexyloxy-4-nitrophenyl]-methanesulfonamide), suppressed the recurrence of allergic inflammation as did the non-selective cyclooxygenase-1/cyclooxygenase-2 inhibitor, indomethacin. The steroidal anti-inflammatory drug, dexamethasone, inhibited the induction of cyclooxygenase-2, and suppressed the allergic inflammation. These findings strongly suggested that cyclooxygenase-2 induced by the antigen challenge plays a role in the recurrence of inflammation induced by the allergic mechanism.

Animals↗

Suppression of cytokine synthesis, integrin expression and chronic inflammation by inhibitors of cytosolic phospholipase A2.

To define the isoform of phospholipases A2 active in inflammation we evaluated the effects of low-molecular-weight inhibitors of secretory and cytosolic phospholipases A2. We found that inhibitors of cytosolic phospholipase A2 had therapeutic efficacy in an in vivo model of chronic inflammation (rat adjuvant arthritis), whereas inhibitors of secretory phospholipase A2 had no beneficial effect. In vitro, inhibitors of cytosolic phospholipase A2 diminished surface expression of Mac-1 (CD11b/CD18) beta2-integrin on calcium ionophore-stimulated human blood granulocytes and suppressed synthesis of interleukin-1beta in lipopolysaccharide-stimulated human blood monocytes and U937 cells by reducing mRNA levels. Lipid mediators promote Mac-1 exocytosis and transcription of interleukin-1beta, which further enhances cytosolic phospholipase A2 activity and expression. Thus, superinduction of cytosolic phospholipase A2 may establish a positive feedback loop, converting acute inflammation into chronic inflammation. Consequently, inhibitors of cytosolic phospholipase A2 may prevent inflammation in vivo by interfering with cellular activation and infiltration. We conclude that cytosolic phospholipase A2 but not secretory phospholipase A2 is the predominant enzyme in inflammatory signalling.

Animals↗

Humoral markers of inflammation and endothelial dysfunction in relation to adiposity and in vivo insulin action in Pima Indians.

Several studies have shown that humoral markers of inflammation and endothelial dysfunction are predictive of macrovascular events, and correlated with indirect measures of adiposity and insulin action, thus providing a possible link between obesity, insulin resistance and atherosclerosis. We examined the relationship between humoral markers of inflammation and endothelial dysfunction and direct measures of adiposity and insulin action in Pima Indians, a population with a very high prevalence of obesity and insulin resistance, but a relatively low propensity for atherosclerotic disease. Fasting plasma concentrations of the inflammatory markers C-reactive protein (CRP), secretory phospholipase A2 (sPLA2) and soluble intercellular adhesion molecule-1 (sICAM-1) and of the endothelial markers E-selectin and von Willebrand factor (vWF) were measured in 32 non-diabetic Pima Indians (18 M/14 F, age 27+/-1 years) in whom percent body fat and insulin-stimulated glucose disposal (M) were assessed by DEXA and a hyperinsulinemic clamp, respectively. CRP, sPLA2, and sICAM-1 were all positively correlated with percent body fat (r=0.71, 0.57, and 0.51, all P<0.01). E-selectin and vWF were not correlated with percent body fat, but were negatively correlated with M (r= -0.65 and -0.46, both P<0.001) and positively correlated with CRP (r=0.46, and 0.33, both P<0.05). These findings indicate that humoral markers of inflammation increase with increasing adiposity in Pima Indians whereas humoral markers of endothelial dysfunction increase primarily in proportion to the degree of insulin resistance and inflammation. Thus, obesity and insulin resistance appear to be associated with low-grade inflammation and endothelial dysfunction, respectively, even in an obesity- and diabetes-prone population with relatively low propensity for atherosclerosis.

Adipose Tissue↗

Circulating markers of inflammation and atherosclerosis.

Atherosclerosis is nowadays generally accepted as an inflammatory disease. It is known that local inflammation occurs in the formation the plaques, as macrophages and other immuno-competent cells are present in the lesions from an early stage, and it is also known that inflammation plays an important role in the weakening of the fibrous cap of the advanced plaque, eventually leading to plaque rupture and acute coronary syndromes. The present review focuses on two questions. First, if circulating markers of inflammation could differentiate between healthy subjects and those with atherosclerotic manifestations. Second, if those markers could differentiate between those with a stable atherosclerotic disease, such as stable angina pectoris, and those prone to unstable manifestations of atherosclerosis, such as acute coronary syndromes. Using data from both cross-sectional and prospective studies it could be shown that the majority of the studies which had investigated the role of markers for systemic inflammation, such as CRP, leukocyte count, serum fibrinogen and different cytokines, found elevated levels in patients with atherosclerosis and especially so in those with an unstable coronary disease. The same pattern was found when inflammatory markers with a vascular origin, such as the adhesion molecules, were investigated. Thus, based on the literature it is obvious that circulating markers of inflammation have a role as risk factors for unstable manifestations of atherosclerosis, but it is still unclear whether the different inflammatory markers merely are markers, or if they in an active way contribute to the development and progression of the atherosclerotic disease in their own.

Arteriosclerosis↗

Kupffer-cell depletion attenuates colonic and extracolonic granulomatous inflammation in chronic colitis.

Intramural injection of peptidoglycan-polysaccharide polymers into the distal colon in rats induces granulomatous colitis associated with extracolonic manifestations. We sought to clarify the effects of Kupffer-cell depletion induced by the intravenous administration of gadolinium on colonic and extracolonic inflammation in this model. The effects of Kupffer-cell depletion on acute and chronic inflammation were evaluated 3 days and 3 weeks after injection of peptidoglycan-polysaccharide, respectively. We assessed the effects of gadolinium on colonic cytokine levels in vivo and the viability of elicited peritoneal macrophages and peptidoglycan-polysaccharide-induced production of nitrite, an indirect index of nitric oxide production, by these cells in vitro. A single injection of gadolinium caused a marked decrease in the number of Kupffer cells stained with antibodies within 3 days. Gadolinium treatment did not alter acute inflammation at 3 days. Repeated treatment with gadolinium dramatically attenuated grossly observed chronic inflammation, including thickening of colon wall, hepatic and splenic nodules, and swelling of foot joints; and significantly reduced the proportional areas occupied by granulomas in the colon, liver, and spleen at 3 weeks. These protective effects were reflected in significant reduction in colon and liver weights; gross scores; colonic myeloperoxidase activity, an indirect quantitative index of granulocyte infiltration; colonic interleukin-1beta levels; plasma nitrite and nitrate levels; and decreased tendency toward arthritis. Although gadolinium did not cause injury in elicited peritoneal macrophages in vitro, the compound dose-dependently attenuated peptidoglycan-polysaccharide-induced production of nitrite by these cells. Chronic Kupffer-cell depletion attenuates peptidoglycan-polysaccharide-induced granulomatous inflammation in the colon, liver, and spleen and reduces the incidence of arthritis, possibly by suppressing the production of interleukin-1beta and nitric oxide.

Animals↗

Anemia of acute inflammation in children.

We measured sequential changes in hemoglobin concentration and erythrocyte sedimentation rate in 27 previously healthy children hospitalized for a variety of moderately severe acute inflammatory processes. Among 18 retrospectively studied children, 61% had mild anemia for age on admission, and Hgb values dropped greater than 2 SD in 83% during active inflammation. During recovery, Hgb concentrations spontaneously rose greater than 1.3 gm/dl in 79% of the children. Mean Hgb drop was 1.8 gm/dl in 5.6 days, representing an average noniatrogenic blood loss of 107 ml, among nine prospectively studied children. Only one of these had laboratory evidence of hemolysis, and none had clinical evidence of bleeding or overhydration. Results of both studies combined showed that a mean 13% Hgb drop during active inflammation was followed by a mean 24% Hgb rise during resolution of acute inflammation. We conclude that most children with moderately severe acute inflammation experience a significant drop in Hgb within 1 week of illness onset, regardless of the specific cause of inflammation. In general, this mild to moderate anemia resolves without hematinic therapy.

Acute Disease↗

Acute stress decreases inflammation at the site of infection. A role for nitric oxide.

Exposure to acute stress modulates immune function. Most research regarding stress and immunity has described the deleterious effects of stress. Recent studies, however, indicate that acute stress enhances many features of innate immunity. For example, exposure to acute stress reduced the time required to resolve inflammation produced by subcutaneous injection of streptomycin-killed, benign bacteria. It is unclear if this change in inflammation would be advantageous to the organism if challenged with living, infectious bacteria. Thus, the current experiments examined the effect of acute stressor exposure on inflammation development and resolution after a naturalistic, live bacterial challenge. In addition, nitric oxide (NO), an important bactericidal mediator, was measured at the inflammatory site. Rats (F344) were exposed to acute stress (100, 5-s, 1.6 mA tailshocks) and subcutaneously injected with live Escherichia coli ( approximately 2.5 x 10(9) colony forming units [CFU]). Stressed rats attained their peak inflammatory size quicker, resolved their inflammation 10-14 days faster, experienced less bacterial-induced weight loss and released 300% greater NO at the inflammatory site than nonstressed controls. Thus, acute stress improved recovery from bacterially induced inflammation possibly due to local elevations in NO.

Acute Disease↗