interleukin-8 and Osteomyelitis

The chemotactic cytokine interleukin-8 (IL-8) plays an important role in attraction and activation of polymorphonuclear leukocytes in infection and inflammation. A pilot study was conducted to determine if radiolabeled IL-8 would depict infection in humans.. Human recombinant IL-8 (rhIL-8) labeled with (131)I (specific activity, 0.4-0.7 MBq [11-18 microCi] (131)I/microg IL-8) was injected intravenously into 8 diabetic patients with active foot infections and evidence of osteomyelitis, 2 patients with successfully treated osteomyelitis, and 1 patient with cellulitis of the thumb.. Focal accumulation of (131)I-rhIL-8 was seen in 8 of 8 patients with active foot infection and diffuse uptake was seen in the thumb of the 1 patient with cellulitis. In the 2 patients with successfully treated bone infection, multiphase (99m)Tc-hydroxyethylene diphosphonate bone scans were negative early, but late-phase (>3 h) uptake depicted degenerative lesions that did not image with (131)I-rhIL-8.. (131)I-rhIL-8 accumulates rapidly within infected foci in osteomyelitis and cellulitis but not in successfully treated infections or degenerative joint disease.

Topics: Adult; Aged; Diabetes Complications; Diabetic Foot; Female; Humans; Image Processing, Computer-Assisted; Infections; Interleukin-8; Iodine Radioisotopes; Male; Middle Aged; Osteomyelitis; Radionuclide Imaging; Radiopharmaceuticals; Recombinant Proteins

Staphylococcus aureus is the principal causative agent of osteomyelitis, a serious bacterial infection of bone that is associated with progressive inflammatory damage. Bone-forming osteoblasts have increasingly been recognized to play an important role in the initiation and progression of detrimental inflammation at sites of infection and have been demonstrated to release an array of inflammatory mediators and factors that promote osteoclastogenesis and leukocyte recruitment following bacterial challenge. In the present study, we describe elevated bone tissue levels of the potent neutrophil-attracting chemokines CXCL1, CXCL2, CXCL3, CXCL5, CCL3, and CCL7 in a murine model of posttraumatic staphylococcal osteomyelitis. RNA sequencing (RNA-Seq) gene ontology analysis of isolated primary murine osteoblasts showed enrichment in differentially expressed genes involved in cell migration and chemokine receptor binding and chemokine activity following S. aureus infection, and a rapid increase in the expression of mRNA encoding CXCL1, CXCL2, CXCL3, CXCL5, CCL3, and CCL7, in these cells. Importantly, we have confirmed that such upregulated gene expression results in protein production with the demonstration that S. aureus challenge elicits the rapid and robust release of these chemokines by osteoblasts and does so in a bacterial dose-dependent manner. Furthermore, we have confirmed the ability of soluble osteoblast-derived chemokines to elicit the migration of a neutrophil-like cell line. As such, these studies demonstrate the robust production of CXCL1, CXCL2, CXCL3, CXCL5, CCL3, and CCL7 by osteoblasts in response to S. aureus infection, and the release of such neutrophil-attracting chemokines provides an additional mechanism by which osteoblasts could drive the inflammatory bone loss associated with staphylococcal osteomyelitis.

Topics: Animals; Chemokine CCL3; Chemokine CCL7; Chemokine CXCL1; Chemokine CXCL2; Chemokines; Interleukin-8; Mice; Neutrophils; Osteoblasts; Osteomyelitis; Staphylococcal Infections; Staphylococcus aureus

Bone infection or osteomyelitis is characterized by uncontrolled inflammation and destructive bone loss although little is known about immunopathogenesis of infection. We investigated control of chemokine secretion from osteoblasts infected with either Mycobacterium tuberculosis, which normally elicits a granulomatous host response, or Staphylococcus aureus, which drives a host response dominated by neutrophil influx. We show that M. tuberculosis infection of cultured and primary osteoblasts induces extensive secretion of the chemokines interleukin (IL)-8, inducible protein (IP) 10, RANTES, and monocyte chemoattractant protein (MCP) 1 within 72 h (1630 +/- 280 pg/ml per 4 x 10(5) cells, 74,130 +/- 8480 pg/ml per 4 x 10(5) cells, 18,330 +/- 3040 pg/ml per 4 x 10(5) cells, and 138,670 +/- 13,340 pg/ml per 4 x 10(5) cells, respectively, for MG-63 osteoblasts). S. aureus infection also results in secretion of these chemokines but secretion is delayed and of lesser magnitude (210 +/- 10 pg/ml per 4 x 10(5) cells, 11,570 +/- 1240 pg/ml per 4 x 10(5) cells, 930 +/- 34 pg/ml per 4 x 10(5) cells, and 13,770 +/- 720 pg/ml per 4 x 10(5) cells for IL-8, IP-10, RANTES, and MCP-1, respectively). The minimal up-regulation of secretion of the neutrophil attractant IL-8 in staphylococcal infection is both striking and unexpected. In both infections, chemokine secretion was dependent on the presence of live organisms. Differences in kinetics and magnitude of chemokine secretion are associated with distinct patterns of mRNA expression, as assessed by ribonuclease protection assay (RPA) and reverse-transcription polymerase chain reaction (RT-PCR). In addition, nuclear localization of the transcription factor activator protein (AP) 1 in M. tuberculosis-infected osteoblasts also is distinct as compared with S. aureus-infected cells. In summary, this study shows that osteoblasts have an important pathogen-specific role in control of chemokine gene expression and secretion during the human immune response to osteomyelitis.

Topics: Base Sequence; Cell Line; Chemokine CCL2; Chemokine CCL5; Chemokine CXCL10; Chemokines; Chemokines, CXC; Gene Expression Regulation; Humans; Interleukin-8; Osteoblasts; Osteomyelitis; RNA, Messenger; Staphylococcal Infections; Transcription Factor AP-1; Tuberculosis, Osteoarticular

Early and accurate diagnosis of osteomyelitis remains a clinical problem. Acute osteomyelitis often occurs in infants and most often is located in the long bones. Radiologic images show changes only in advanced stages of disease. Scintigraphic imaging with (99m)Tc-methylene diphosphonate (MDP), or bone scanning, is much more sensitive in detecting acute osteomyelitis but lacks specificity. We evaluated the performance of (99m)Tc-interleukin-8 (IL-8) in an experimental model of acute osteomyelitis.. Acute pyogenic osteomyelitis was induced in 10 rabbits by inserting sodium morrhuate and Staphylococcus aureus into the medullary cavity of the right femur. The cavity was closed with liquid cement. A sham operation was performed on the left femur. Routine radiographs were obtained just before scintigraphy. Ten days after surgery, the rabbits were divided into 2 groups of 5 animals, received an injection of either 18.5 MBq (111)In-granulocytes or 18.5 MBq (67)Ga-citrate, and were imaged both 24 h after injection and 48 h after injection. On day 12, the rabbits received either 18.5 MBq (99m)Tc-MDP or 18.5 MBq (99m)Tc-IL-8, and serial images were acquired at 0, 1, 2, 4, 8, 12, and 24 h after injection. Uptake in the infected femur was determined by drawing regions of interest. Ratios of infected femur (target) to sham-operated femur (background) (T/Bs) were calculated. After the final images were obtained, the rabbits were killed and the right femur was dissected and analyzed for microbiologic and histopathologic evidence of osteomyelitis.. Acute osteomyelitis developed in 8 of 10 rabbits. All imaging agents correctly detected the acute osteomyelitis in these animals. The extent of infection was optimally visualized with (67)Ga-citrate and delayed bone scanning, whereas diaphyseal photopenia was noted with both (99m)Tc-IL-8 and (111)In-granulocytes. In 1 rabbit with osteomyelitis, imaging results were falsely negative with (111)In-granulocytes and falsely positive with (99m)Tc-MDP. Quantitative analysis of the images revealed that the uptake in the infected region was highest with (67)Ga-citrate (4.9 +/- 0.8 percentage injected dose [%ID]) and (99m)Tc-MDP (4.7 +/- 0.7 %ID), whereas the uptake in the infected area was significantly lower with (99m)Tc-IL-8 (2.2 +/- 0.2 %ID) and (111)In-granulocytes (0.8 +/- 0.2 %ID) (P < 0.0042). In contrast, the T/Bs were significantly higher for (99m)Tc-IL-8 (T/B, 6.2 +/- 0.3 at 4 h after injection) than for (67)Ga-citrate, (99m)Tc-MDP, and (111)In-granulocytes, which had ratios of 1.5 +/- 0.4, 1.9 +/- 0.2, and 1.4 +/- 0.1, respectively (P < 0.0001). Radiography correctly revealed acute osteomyelitis in only 2 of 8 rabbits.. In this rabbit model of osteomyelitis, (99m)Tc-IL-8 clearly revealed the osteomyelitic lesion. Although the absolute uptake in the osteomyelitic area was significantly lower than that obtained with (99m)Tc-MDP and (67)Ga-citrate, the T/Bs were significantly higher for (99m)Tc-IL-8 because of fast background clearance. The ease of preparation, good image quality, and lower radiation burden suggest that (99m)Tc-IL-8 may be a suitable imaging agent for the scintigraphic evaluation of acute osteomyelitis.

Topics: Animals; Female; Femur; Gated Blood-Pool Imaging; Granulocytes; Indium Radioisotopes; Interleukin-8; Organotechnetium Compounds; Osteomyelitis; Rabbits; Radiopharmaceuticals; Receptors, Interleukin; Technetium Tc 99m Medronate

Osteomyelitis, or bone infection, is a major worldwide cause of morbidity. Treatment is frequently unsatisfactory, yet little is known about pathogenesis of infection. Plasma tumor necrosis factor (TNF), interleukin (IL)-6, and IL-8 concentrations were measured before and after lipopolysaccharide stimulation of whole blood from patients with bacterial and tuberculous osteomyelitis and from controls. Patients with bacterial and tuberculous osteomyelitis mounted an acute-phase response and were anemic and febrile. However, plasma IL-6 concentrations were significantly elevated in only tuberculous osteomyelitis patients (vs. controls, P < .05). IL-6 concentrations correlated with erythrocyte sedimentation rate, C-reactive protein level, and plasma albumin concentration, all acute-phase markers. There were no other correlations between cytokine concentrations and clinical data. Following ex vivo stimulation, TNF, IL-6, and IL-8 were secreted equally by patients and controls. In summary, tuberculous osteomyelitis is characterized by elevated systemic IL-6 concentrations associated with an acute-phase response. For further insight into immunopathology of osteomyelitis, studies on infected bone are required.

Topics: Acute-Phase Reaction; Adult; Bacterial Infections; Cytokines; Female; Humans; Interleukin-6; Interleukin-8; Male; Osteomyelitis; Tuberculosis; Tuberculosis, Osteoarticular; Tumor Necrosis Factor-alpha

The local and systemic release of thromboxane A2, prostaglandin I2, leukotriene B4 (LTB4), tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and interleukin-8 (IL-8) were studied before and after operation in 29 patients with acute and 22 with chronic posttraumatic osteomyelitis. Twenty patients without osteomyelitis, who underwent operations for fractures of the lower extremities, served as controls. Blood and tissue samples from the osteomyelitic and control groups were collected under defined conditions and mediators were determined by radioimmunoassay (thromboxane B2, 6-keto-prostaglandin F1 alpha, LTB4) or by enzyme-linked immunosorbent assay (TNF-alpha, IL-1 beta, and IL-8). In addition, common parameters (leukocyte count, C-reactive protein, temperature) were measured. The best correlation with acute disease activity was given by TNF-alpha, IL-6, IL-8, and LTB4. Plasma levels of these mediators in acute osteomyelitis were significantly increased compared to chronic osteomyelitis and to controls, respectively. Tissue samples from osteomyelitic focus showed significantly increased levels for IL-8, IL-6, TNF-alpha, IL-1 beta, and LTB4 in acute osteomyelitis, whereas the values for TxB2 and 6-keto-prostaglandin F1 alpha were only slightly increased compared to the chronic osteomyelitis group. This study describes the local and systemic liberation of various mediators in acute and chronic posttraumatic osteomyelitis in detail for the first time and provides data for pre- and postoperative monitoring of disease activity and demonstrates new pathogenetic and therapeutic aspects of bone modulation in osteomyelitis.

Topics: Acute Disease; Adult; Case-Control Studies; Chronic Disease; Cytokines; Eicosanoids; Epoprostenol; Female; Fractures, Bone; Humans; Interleukin-6; Interleukin-8; Leukotriene B4; Male; Middle Aged; Osteomyelitis; Thromboxane A2