The role of IL-15 deficiency in the pathogenesis of virus-induced asthma exacerbations

Rhinovirus infections are the major cause of asthma exacerbations. We hypothesised that IL-15, a cytokine implicated in innate and acquired antiviral immunity, may be deficient in asthma and important in the pathogenesis of asthma exacerbations. We investigated regulation of IL-15 induction by rhinovirus in human macrophages in vitro, IL-15 levels in bronchoalveolar lavage (BAL) fluid and IL-15 induction by rhinovirus in BAL macrophages from asthmatic and control subjects, and related these to outcomes of infection in vivo. Rhinovirus induced IL-15 in macrophages was replication-, NF-κB- and α/β interferon-dependent. BAL macrophage IL-15 induction by rhinovirus was impaired in asthmatics and inversely related to lower respiratory symptom severity during experimental rhinovirus infection. IL-15 levels in BAL fluid were also decreased in asthmatics and inversely related with airway hyperresponsiveness and with virus load during in vivo rhinovirus infection. Deficient IL-15 production in asthma may be important in the pathogenesis of asthma exacerbations.     

The tolerance of the frontal bone to blunt impact

The current understanding of the tolerance of the frontal bone to blunt impact is limited. Previous studies have utilized vastly different methods, which limits the use of statistical analyses to determine the tolerance of the frontal bone. The purpose of this study is to determine the tolerance of the frontal bone to blunt impact. Acoustic emission sensors were used to provide a noncensored measure of the frontal bone tolerance and were essential due to the increase in impactor force after fracture onset. In this study, risk functions for fracture were developed using parametric and nonparametric techniques. The results of the statistical analyses suggest that a 50% risk of frontal bone fracture occurs at a force between 1885 N and 2405 N. Subjects that were found to have a frontal sinus present within the impacted region had a significantly higher risk of sustaining a fracture. There was no association between subject age and fracture force. The results of the current study suggest that utilizing peak force as an estimate of fracture tolerance will overestimate the force necessary to create a frontal bone fracture.     

Magnitude of head impact exposures in individual collegiate football players

The purpose of this study was to quantify the severity of head impacts sustained by individual collegiate football players and to investigate differences between impacts sustained during practice and game sessions, as well as by player position and impact location. Head impacts (N = 184,358) were analyzed for 254 collegiate players at three collegiate institutions. In practice, the 50th and 95th percentile values for individual players were 20.0 g and 49.5 g for peak linear acceleration, 1187 rad/s2 and 3147 rad/s2 for peak rotational acceleration, and 13.4 and 29.9 for HITsp, respectively. Only the 95th percentile HITsp increased significantly in games compared with practices (8.4%, p = .0002). Player position and impact location were the largest factors associated with differences in head impacts. Running backs consistently sustained the greatest impact magnitudes. Peak linear accelerations were greatest for impacts to the top of the helmet, whereas rotational accelerations were greatest for impacts to the front and back. The findings of this study provide essential data for future investigations that aim to establish the correlations between head impact exposure, acute brain injury, and long-term cognitive deficits.     

Advanced glycation end products‐related modulation of cathepsin L and NF‐κB signalling effectors in retinal pigment epithelium lead to augmented response to TNFα

The retinal pigment epithelium (RPE) plays a central role in neuroretinal homoeostasis throughout life. Altered proteolysis and inflammatory processes involving RPE contribute to the pathophysiology of age‐related macular degeneration (AMD), but the link between these remains elusive. We report for the first time the effect of advanced glycation end products (AGE)—known to accumulate on the ageing RPE's underlying Bruch's membrane in situ—on both key lysosomal cathepsins and NF‐κB signalling in RPE. Cathepsin L activity and NF‐κB effector levels decreased significantly following 2‐week AGE exposure. Chemical cathepsin L inhibition also decreased total p65 protein levels, indicating that AGE‐related change of NF‐κB effectors in RPE cells may be modulated by cathepsin L. However, upon TNFα stimulation, AGE‐exposed cells had significantly higher ratio of phospho‐p65(Ser536)/total p65 compared to non‐AGEd controls, with an even higher fold increase than in the presence of cathepsin L inhibition alone. Increased proportion of active p65 indicates an AGE‐related activation of NF‐κB signalling in a higher proportion of cells and/or an enhanced response to TNFα. Thus, NF‐κB signalling modulation in the AGEd environment, partially regulated via cathepsin L, is employed by RPE cells as a protective (para‐inflammatory) mechanism but renders them more responsive to pro‐inflammatory stimuli.     

Paucity of clinical disease despite serological autoimmunity and kidney pathology in lupus-prone New Zealand mixed 2328 mice deficient in BAFF

Constitutive overexpression of B cell-activating factor belonging to the TNF family (BAFF) promotes development of systemic lupus erythematosus (SLE), and treatment of SLE mice with BAFF antagonists ameliorates disease. To determine whether SLE can develop de novo in BAFF-deficient hosts, BAFF-deficient New Zealand Mixed (NZM) 2328 (NZM.Baff(-/-)) mice were generated. In NZM.Baff(-/-) mice, spleen B cells (including CD5(+) B1a and CD5(-) B1b B cells), germinal centers, Ig-secreting cells, and T cells were reduced in comparison to NZM.Baff(+/+) mice. Serum total Ig and autoantibody levels were reduced at 4-6 mo but approached wild-type levels with increasing age, indicating that autoreactive B cells can survive and secrete autoantibodies despite the complete absence of BAFF. At least some of these autoantibodies are nephrophilic in that glomerular deposition of total IgG and IgG1 (but not of IgG2a, IgG2b, or C3) was substantial in NZM.Baff(-/-) mice by 12-13 mo of age. Despite proliferative glomerulonephritis, highlighted by widespread glomerular hyaline thrombi, being common among NZM.Baff(-/-) mice by 6-7 mo of age, severe proteinuria and mortality were greatly attenuated. These results demonstrate that the lifelong absence of BAFF does not protect NZM 2328 mice from serological autoimmunity and renal pathology. Nevertheless, the character of the renal pathology is altered, and the mice are largely spared from clinically overt disease (severe proteinuria and premature death). These observations may have profound ramifications for the use of BAFF antagonists in human SLE and related diseases.     

Bradykinin sensitization of colony-stimulating factor-1-responsive murine marrow progenitors to prostaglandin E. A property of the amino-terminal tetrapeptide fragment

The active sequence in bradykinin (BK) responsible for PGE-aided inhibition of CSF-1-stimulated clonal proliferation of murine mononuclear phagocyte progenitors was determined. In total marrow cultures, BK and (D-Phe7)-BK, a specific BK antagonist, inhibited colony formation by CSF-1 responsive precursors that require two signals, CSF and LPS, for clonal proliferation. (Lys1)-BK, an inactive BK analogue with Lys substituted for the amino-terminal Arg, was inactive. Arg-Pro-Pro-Gly, the amino-terminal tetrapeptide fragment of BK, was fully capable, on a molar basis, of replacing either BK or (D-Phe7)-BK as an inhibitor. Bk, (D-Phe7)-BK, and Arg-Pro-Pro-Gly were not inhibitory for colony formation in cultures containing indomethacin or in cultures depleted of adherent marrow cells. However, in these cultures addition of 10(-9) M PGE2 fully restored inhibition of two-signal-dependent colony formation. PGE2-dependent inhibition by the three peptides was equivalent on a molar basis indicating that Arg-Pro-Pro-Gly contains the sequence responsible for this inhibitory effect of BK and is sufficient to exert PGE-dependent inhibition of two-signal-dependent colony formation. The two-signal-dependent progenitors appear to be in transition to CSF competence suggesting that BK and PGE produced in an hematopoietic environment may act together to limit the production of new macrophages by inhibiting progenitors in transition to CSF competence.     

Increased uptake of folate conjugates by activated macrophages in experimental hyperlipemia

In the pathogenesis of atherosclerosis, macrophages become activated and play a crucial role in plaque formation. Activated synovial macrophages have recently been shown to express receptors for folic acid. We have determined whether activated macrophages also over-express folate receptor (FR) in atherosclerosis. Most normal cells express little or no FR, and, if FR is present on activated macrophages, folate-linked compounds and drugs could be selectively targeted to those cells that do express FR. To evaluate the FR on macrophages of atherosclerotic animals, golden Syrian hamsters were maintained on a hyperlipidemic diet until extensive vascular lesions had developed. Uptake of folic acid conjugated to fluorescent tags was then examined in tissue fragments from lesion-prone areas, and peritoneal activated macrophages were harvested from the same animals. Spectrofluorimetric and fluorescence microscopic analyses showed a significantly greater uptake of folate-conjugates by peritoneal macrophages of hyperlipidemic hamsters compared with those of hamsters fed a normal or folate-deficient diet. Systemically administered folate-fluorescent conjugates were found to accumulate as bright spots in protrusions of atherosclerotic plaques populated by macrophages, whereas a low level of fluorescence was detected uniformly dispersed across the lesion. The uptake of the folate conjugate by U937 macrophage cells grown in a high-lipid culture medium was significantly higher than in controls. Our data thus indicate that hyperlipidemic conditions induce an increased uptake of folate attributable to the over-expression of FRs on activated macrophages. This increase in FR expression can be exploited to deliver folate-linked compounds selectively to atherosclerotic lesions. This work was supported by a grant from the Romanian Academy and Ministry of Education, Research and Technology, Bucharest, Romania, and partially by a grant from Endocyte and the Indiana 21st Century Fund.     

Comparison of techniques permitting to detect apoptosis in situ

Several morphological and biochemical techniques are in use for identification of apoptotic and necrotic cells in a studied cell population. It is essential to define not only the type of cell death but also to identify the apoptotic process itself, which represents a multistage, active process, requiring activation of a molecular event cascade. In the present study, we have examined and discussed effectiveness of the selected techniques detecting apoptosis in lymphocytes exposed to incubation at an elevated temperature. The appraisal involved detection of caspase-3 active form, detection of Bcl-2, TUNEL reaction, the comet assay and electrophoresis of DNA.