TNFα blockade mediates bone protection in antigen-induced arthritis by reducing osteoclast precursor supply.

Bone protective effects of TNFα inhibition in rheumatoid arthritis are thought to be mediated by inhibiting synovial osteoclast differentiation and activity. However, it has not been addressed, if TNFα inhibitors alter the pool of peripheral osteoclast precursor cells (OPCs). Here, we blocked TNFα function in C57BL/6 mice with antigen induced arthritis (AIA) using the soluble TNFα receptor etanercept. Synovial bone lesions and osteoclasts were markedly reduced upon Etanercept in the early chronic phase of AIA. Unexpectedly this was not associated with a reduced recruitment of circulating OPCs to the arthritic joint nor to reduced synovial inflammation. In contrast we found that OPC numbers in bone marrow and blood were significantly reduced. Overall our study suggests that arrest of osteoclast mediated bone lesions upon inhibition of TNFα is, at least initially, based on reduced OPC availability in the periphery, and not on OPC recruitment or local anti-inflammatory effects in the arthritic joint.

Blockade of CXCR1/2 chemokine receptors protects against brain damage in ischemic stroke in mice.

OBJECTIVE: Ischemic stroke may result from transient or permanent reductions of regional cerebral blood flow. Polymorphonuclear neutrophils have been described as the earliest inflammatory cells to arrive in ischemic tissue. CXCR1/2 receptors are involved in the recruitment of these cells. However, the contribution of these chemokine receptors during transient brain ischemia in mice remains poorly understood. In this work, we investigated the effects of reparixin, an allosteric antagonist of CXCR1/2 receptors, in a model of middle cerebral artery occlusion and reperfusion in mice. METHODS: C57BL/6J male mice treated with reparixin or vehicle were subjected to a middle cerebral artery occlusion procedure 1 h after the treatment. Ninety minutes after ischemia induction, the monofilament that prevented blood flow was removed. Twenty-four hours after the reperfusion procedure, behavioral changes, including motor signs, were analyzed with the SmithKline/Harwell/lmperial College/Royal Hospital/Phenotype Assessment (SHIRPA) battery. The animals were sacrificed, and brain tissue was removed for histological and biochemical analyses. Histological sections were stained with hematoxylin and eosin, neutrophil infiltration was estimated by myeloperoxidase activity and the inflammatory cytokine IL-iß was measured by ELISA. RESULTS: Pre-treatment with reparixin reduced the motor deficits observed in this model of ischemia and reperfusion. Myeloperoxidase activity and IL-iß were reduced in the reparixin-treated group. Histological analysis revealed that ischemic injury was also attenuated by reparixin pre-treatment. CONCLUSIONS: Our results suggest that the blockade of the CXCR1/2 receptors by reparixin promotes neuroprotective effects by reducing the levels of polymorphonuclear infiltration in the brain and the tissue damage associated with middle cerebral artery occlusion and reperfusion.

Impact of an exercise program on muscular and functional performance and plasma levels of interleukin 6 and soluble receptor tumor necrosis factor in prefrail community-dwelling older women: a randomized controlled trial.

OBJECTIVE: To examine the impact of a muscle resistance program (MRP) on muscular and functional performance and on interleukin 6 (IL-6) and soluble tumor necrosis factor receptor-1 (sTNFr1) plasma levels in prefrail community-dwelling women. DESIGN: Randomized controlled trial crossover design with a postintervention and short-term follow-up. SETTING: University hospital. PARTICIPANTS: Prefrail community-dwelling women (N=32; ≥65y). INTERVENTION: The MRP was designed based on the exercise at 75% of each participant's maximum load (10wk, 3 times/wk). MAIN OUTCOME MEASURES: Plasma concentrations of IL-6 and sTNFr1 (high-sensitivity enzyme-linked immunosorbent assay kits), muscle strength of the knee extensors (isokinetic), and functional performance (Timed Up & Go [TUG] test and 10-meter walk test [10MWT]). RESULTS: There were significant differences in functional and muscular performance between the pre-MRP, post-MRP, and 10-week follow-up period. After the MRP, both functional (TUG, pre-MRP=11.1s vs post-MRP=10.4s, P=.00; 10MWT, pre-MRP=4.9s vs post-MRP, 4.4s, P=.00) and muscular performances (pre-MRP=77.8% and post-MRP=83.1%, P=.02) improved. After cessation of the MRP (follow-up period), sTNFr1 plasma levels increased by 21.4% at 10-week follow-up (post-MRP, 406.4pg/mL; 10-week follow-up, 517.0pg/mL; P=.03). There were significant differences in sTNFr1 (P=.01). CONCLUSIONS: The MRP was effective in improving functional and muscular performances, although alterations in plasma levels of IL-6 and sTNFr1 could not be identified after the MRP. Cessation of the MRP after 10 weeks resulted in increased plasma levels of sTNFr1.

Blockade of CXCR1/2 chemokine receptors protects against brain damage in ischemic stroke in mice

OBJECTIVE: Ischemic stroke may result from transient or permanent reductions of regional cerebral blood flow. Polymorphonuclear neutrophils have been described as the earliest inflammatory cells to arrive in ischemic tissue. CXCR1/2 receptors are involved in the recruitment of these cells. However, the contribution of these chemokine receptors during transient brain ischemia in mice remains poorly understood. In this work, we investigated the effects of reparixin, an allosteric antagonist of CXCR1/2 receptors, in a model of middle cerebral artery occlusion and reperfusion in mice. METHODS: C57BL/6J male mice treated with reparixin or vehicle were subjected to a middle cerebral artery occlusion procedure 1 h after the treatment. Ninety minutes after ischemia induction, the monofilament that prevented blood flow was removed. Twenty-four hours after the reperfusion procedure, behavioral changes, including motor signs, were analyzed with the SmithKline/Harwell/lmperial College/Royal Hospital/Phenotype Assessment (SHIRPA) battery. The animals were sacrificed, and brain tissue was removed for histological and biochemical analyses. Histological sections were stained with hematoxylin and eosin, neutrophil infiltration was estimated by myeloperoxidase activity and the inflammatory cytokine IL-iβ was measured by ELISA. RESULTS: Pre-treatment with reparixin reduced the motor deficits observed in this model of ischemia and reperfusion. Myeloperoxidase activity and IL-iβ were reduced in the reparixin-treated group. Histological analysis revealed that ischemic injury was also attenuated by reparixin pre-treatment. CONCLUSIONS: Our results suggest that the blockade of the CXCR1/2 receptors by reparixin promotes neuroprotective effects by reducing the levels of polymorphonuclear infiltration in the brain and the tissue damage associated with middle cerebral artery occlusion and reperfusion.

HIV-1 Nef interferes with T-lymphocyte circulation through confined environments in vivo.

HIV-1 negative factor (Nef) elevates virus replication and contributes to immune evasion in vivo. As one of its established in vitro activities, Nef interferes with T-lymphocyte chemotaxis by reducing host cell actin dynamics. To explore Nef's influence on in vivo recirculation of T lymphocytes, we assessed lymph-node homing of Nef-expressing primary murine lymphocytes and found a drastic impairment in homing to peripheral lymph nodes. Intravital imaging and 3D immunofluorescence reconstruction of lymph nodes revealed that Nef potently impaired T-lymphocyte extravasation through high endothelial venules and reduced subsequent parenchymal motility. Ex vivo analyses of transendothelial migration revealed that Nef disrupted T-lymphocyte polarization and interfered with diapedesis and migration in the narrow subendothelial space. Consistently, Nef specifically affected T-lymphocyte motility modes used in dense environments that pose high physical barriers to migration. Mechanistically, inhibition of lymph node homing, subendothelial migration and cell polarization, but not diapedesis, depended on Nef's ability to inhibit host cell actin remodeling. Nef-mediated interference with in vivo recirculation of T lymphocytes may compromise T-cell help and thus represents an important mechanism for its function as a HIV pathogenicity factor.

Experimental arthritis exacerbates Aggregatibacter actinomycetemcomitans-induced periodontitis in mice.

AIM: This study aimed to investigate whether chronic antigen-induced arthritis (AIA) influences infection-induced periodontitis (PD) in mice and whether PD modifies the clinical course of AIA. The contribution of anti-TNF-α therapy was also evaluated. MATERIALS AND METHODS: The PD was induced in C57BL/6 mice by oral infection with Aggregatibacter actinomycetemcomitans. AIA was induced after infection. Anti-TNF-α and chlorhexidine therapies were used to investigate the role of TNF-α and oral infection on PD and AIA interaction. Maxillae, knee joints, lymph nodes and serum samples were used for histomorphometric, immunoenzymatic and/or real time-PCR analyses. RESULTS: Antigen-induced arthritis exacerbated alveolar bone loss triggered by PD infection. In contrast, PD did not influence AIA in the evaluated time-points. PD exacerbation was associated with enhanced production of IFN-γ in maxillae and expression of the Th1 transcription factor tBET in submandibular lymph nodes. Increased serum levels of IL-6 and C-reactive protein were also detected. Anti-TNF-α and antiseptic therapies prevented the development and exacerbation of infectious-PD. Anti-TNF-α therapy also resulted in reduced expression of IFN-γ, TNF-α and IL-17 in maxillae. CONCLUSIONS: Altogether, the current results indicate that the exacerbation of infection-induced PD by arthritis is associated with an alteration in lymphocyte polarization pattern and increased systemic immunoreactivity. This process was ameliorated by anti-TNF-α and antiseptic therapies.

Peripheral blood mono-nuclear cells derived from Alzheimer's disease patients show elevated baseline levels of secreted cytokines but resist stimulation with ß-amyloid peptide.

OBJECTIVES: Among several other factors, the neuro-toxic ß-amyloid peptide (ßAP)-induced inflammatory mechanisms have also been implicated in the pathogenesis of Alzheimer's dementia (AD). Cytokines have recently emerged as prime candidates underlying this immune reaction. The purpose of this study was to evaluate the inflammatory response of peripheral blood mono-nuclear cells (PBMC) in AD. DESIGN: Cross-sectional (observational) study. SETTING: Behavioral and cognitive neurology clinic of the Universidade Federal de Minas Gerais in Belo Horizonte, Brazil. PARTICIPANTS: AD patients (n=19), healthy elderly (n=19) and young (n=14) individuals. MEASUREMENTS: Cytokine levels were assessed by enzyme-linked immuno-sorbent assay (ELISA) after exposing cells to a broad range of ßAP concentrations (10(-4)-10(-10)M) as a stimulus. AD samples were weighed against leukocytes harvested from non-demented young and elderly subjects. RESULTS: Cytokine production of PBMCs in the youth was characterized by low baseline levels when compared to cells from the older generation. In the aging population, AD cells were distinguished from the healthy elderly sub-group by an even higher basal cytokine secretion. The low resting concentration in young individuals was markedly increased after treatment with ßAP, however cells from the elderly, irrespective of their disease status, showed unchanged cytokine release following ßAP administration. Non-specific activation of PBMCs with anti-CD3/CD28 antibodies resulted in elevated interleukin (IL)-1ß concentrations in AD. CONCLUSIONS: These results demonstrate a general over-production of cytokines and resistance to ßAP in the old comparison group, with a more pronounced disruption/boosted pattern in AD. Our findings are in line with the hypothesis of "inflammaging", i.e. an enhanced inflammatory profile with normal aging and a further perturbed environment in AD. The observed cytokine profiles may serve as diagnostic biomarkers in dementia.

Evaluation of the inflammatory response to two different intensities of exercise in individuals with heart failure.

The aim of this study is to compare the response of interleukin-6 (IL-6) and soluble tumor necrosis factor alpha receptor 1 (s-TNFr1) to two submaximal intensities of exercise in individuals with heart failure (HF). Thirty-two HF individuals aged 45.53 ± 9.41 years, classes II and III of the New York Heart Association (NYHA) classification underwent two sessions of exercise at low and moderate intensities with blood analysis at baseline, exercise and after exercise. The differences were evaluated by Friedman test and factorial ANOVA. Alpha = 5% was considered. No difference in IL-6 was detected for low intensity. At moderate intensity, there was a significant increase after exercise. The s-TNFr1 increased in moderate-intensity exercise and went back to baseline levels after it. A session of moderate-intensity exercise is better than low-intensity exercise at promoting positive immediate inflammatory responses in individuals with HF class II and III of the NYHA.

Experimental arthritis triggers periodontal disease in mice: involvement of TNF-α and the oral Microbiota.

Rheumatoid arthritis (RA) and periodontal disease (PD) are prevalent chronic inflammatory disorders that affect bone structures. Individuals with RA are more likely to experience PD, but how disease in joints could induce PD remains unknown. This study aimed to experimentally mimic clinical parameters of RA-induced PD and to provide mechanistic findings to explain this association. Chronic Ag-induced arthritis (AIA) was triggered by injection of methylated BSA in the knee joint of immunized mice. Anti-TNF-α was used to assess the role of this cytokine. Intra-articular challenge induced infiltration of cells, synovial hyperplasia, bone resorption, proteoglycan loss, and increased expression of cytokines exclusively in challenged joints. Simultaneously, AIA resulted in severe alveolar bone loss, migration of osteoclasts, and release of proinflammatory cytokines in maxillae. Anti-TNF-α therapy prevented the development of both AIA and PD. AIA did not modify bacterial counts in the oral cavity. PD, but not AIA, induced by injection of Ag in immunized mice was decreased by local treatment with antiseptic, which decreased the oral microbiota. AIA was associated with an increase in serum C-reactive protein levels and the expression of the transcription factors RORγ and Foxp3 in cervical lymph nodes. There were higher titers of anti-collagen I IgG, and splenocytes were more responsive to collagen I in AIA mice. In conclusion, AIA-induced PD was dependent on TNF-α and the oral microbiota. Moreover, PD was associated with changes in expression of lymphocyte transcription factors, presence of anti-collagen Abs, and increased reactivity to autoantigens.

Intravital microscopy to study leukocyte recruitment in vivo.

The intravital microscopy is a valuable tool to capture images of cells in living organisms and to make studies of molecular determinants of leukocyte trafficking easier. Using this technique, we can directly visualize and measure each step of the leukocyte recruitment paradigm, including leukocyte rolling flux, rolling velocity, adhesion, and emigration. Thus, it is possible to understand the process involved in leukocyte homing as well as the cell recruitment to inflammatory tissues. Nowadays, two types of intravital microscopy are used routinely. The light microscopy is used to assess migration of intravascular cells in thin, tissues which must be sufficiently translucent. Epifluorescence microscopy allows the visualization of the microcirculation while permitting the distinction of leukocyte subpopulations in solid organs.

Anti-inflammatory effects of the activation of the angiotensin-(1-7) receptor, MAS, in experimental models of arthritis.

Activation of the renin-angiotensin (Ang) system induces inflammation via interaction between Ang II and type 1 receptor on leukocytes. The relevance of the new arm of the renin-Ang system, namely Ang-converting enzyme-2/Ang-(1-7)/Mas receptor, for inflammatory responses is not known and was investigated in this study. For this purpose, two experimental models were used: Ag-induced arthritis (AIA) in mice and adjuvant-induced arthritis (AdIA) in rats. Male C57BL/6 wild-type or Mas(-/-) mice were subjected to AIA and treated with Ang-(1-7), the Mas agonist AVE 0991, or vehicle. AdIA was performed in female rats that were given AVE 0991 or vehicle. In wild-type mice, Mas protein is expressed in arthritic joints. Administration of AVE 0991 or Ang-(1-7) decreased AIA-induced neutrophil accumulation, hypernociception, and production of TNF-α, IL-1ß, and CXCL1. Histopathological analysis showed significant reduction of inflammation. Mechanistically, AVE 0991 reduced leukocyte rolling and adhesion, even when given after Ag challenge. Mas(-/-) mice subjected to AIA developed slightly more pronounced inflammation, as observed by greater neutrophil accumulation and cytokine release. Administration of AVE 0991 was without effect in Mas(-/-) mice subjected to AIA. In rats, administration of AVE 0991 decreased edema, neutrophil accumulation, histopathological score, and production of IL-1ß and CXCL1 induced by AdIA. Therefore, activation of Mas receptors decreases neutrophil influx and cytokine production and causes significant amelioration of arthritis in experimental models of arthritis in rats and mice. This approach might represent a novel therapeutic opportunity for arthritis.

sTNFR-1 is an early inflammatory marker in community versus institutionalized elderly women.

OBJECTIVE AND DESIGN: To evaluate plasma sTNFR-1 and IL-6 levels and correlate with hand grip in the institutionalized and community living Brazilian elderly. MATERIAL: A convenience sample of 110 elderly women (71.17 + or - 7.44 years) was selected. Plasma sTNFR-1 and IL-6 levels were measured by ELISA. For the measurement of hand grip, a JAMAR dynamometer was used. RESULTS: Plasma concentrations of inflammatory markers were significantly higher in institutionalized elderly (sTNFR-1: 479 + or - 22 pg/mL; IL-6: 6.3 + or - 0.8 pg/mL) than in community-dwelling elderly (sTNFR-1: 329 + or - 24 pg/mL; IL-6: 2.5 + or - 0.4 pg/mL; P < 0.0001). Institutionalized elderly had reduced hand grip (15 + or - 0.8 Kgf) in comparison to community dwelling elderly (23 + or - 0.6 Kgf; P < 0.05). When individuals were subdivided in age groups, sTNFR-1 was higher in community dwelling versus institutionalized elderly in the 60-70 age range. CONCLUSIONS: Our results demonstrate that being institutionalized has an impact on levels of inflammatory markers.

Mechanisms of the airway hyperresponsiveness induced by Strongyloides venezuelensis infection in rats: role of capsaicin-sensitive neurons.

Strongyloides venezuelensis migrates through the lungs and induces airway hyperresponsiveness (AHR). The present study evaluated the role of C-fibers in mediating airway inflammation and AHR after infection of rats with S. venezuelensis. Neonatal treatment with capsaicin effectively depleted sensory nerves. This was accompanied by inhibition of the AHR induced by S. venezuelensis infection. In contrast, capsaicin treatment greatly enhanced pulmonary inflammation, eosinophil influx and the local production of TNF-alpha. In conclusion, this is the first demonstration that, akin to viral and allergic AHR, permanent loss of sensory nerve C-fibers also reduces AHR induced by infection with a helminth.

Correlation between manual muscle strength and interleukin-6 (IL-6) plasma levels in elderly community-dwelling women.

Sarcopenia is a loss of muscle mass related to aging and leads to muscle performance decline. An increase in inflammatory mediator levels, especially of IL-6, has been associated to reduced muscle strength in the elderly. The aim of the present cross-sectional study was to correlate IL-6 plasma levels with manual muscle strength (MMS) in 63 community-dwelling elderly women. (71.2+/-7.4years). IL-6 was measured using enzyme-linked immunosorbent assay (ELISA) and MMS was measured using the JAMAR dynamometer. Pearson's test was used to explore the relationship between the outcomes at the significance level of alpha=0.05. IL-6 levels (2.56+/-3.44pg/ml) and MMS (22.86+/-4.62kgf) exhibited an inverse correlation (r=-0.2673 and p=0.0373). The increase in IL-6 plasma levels possibly contributed toward the reduction in manual muscle strength among the elderly women studied.

Increased serum levels of inflammatory markers in chronic institutionalized patients with schizophrenia.

UNLABELLED: Activation of the cytokine systems may be involved in the neuropathological changes occurring in the central nervous systems of schizophrenic patients. However, associations between the levels of cytokines and the severity of symptoms have not been completely established. OBJECTIVE: It was the aim of this study to evaluate serum levels of tumor necrosis factor (TNF)-alpha and their soluble receptors (sTNFR) in schizophrenic patients and healthy controls. METHODS: Forty male institutionalized schizophrenic patients (mean age +/- SD, 52.3 +/- 9.9 years) and 20 asymptomatic matched controls were recruited. The severity of symptoms was assessed using the Brief Psychiatric Rating Scale, the Positive and Negative Syndrome Scale and the Abnormal Involuntary Movement Scale. Serum levels of cytokines were measured by ELISAs. RESULTS: Serum levels of sTNFR1 and sTNFR2 were increased in schizophrenic patients when compared with controls (all p < 0.05), but there was no difference in TNF-alpha levels. There was no correlation between the length of disease/hospitalization or the severity of symptoms and the serum levels of these molecules. CONCLUSION: Inflammatory markers are increased in schizophrenia but they do not correlate with symptom severity.

Platelet activating factor receptors drive CXC chemokine production, neutrophil influx and edema formation in the lungs of mice injected with Tityus serrulatus venom.

Lung injury is a common finding and a frequent cause of death in cases of severe human envenoming by scorpion sting. The present work investigated the effects of pretreatment with a platelet activation factor receptor (PAFR) antagonist and a CXCR2 inhibitor on the lung injury induced by subcutaneous injection of Tityus serrulatus venom (TsV) in mice. Lung injury was assessed by evaluating the extravasation of Evans blue dye, as an index of increased vascular permeability, the neutrophil accumulation (mieloperoxidase activity), the concentration of tumor necrosis factor-alpha (TNF-alpha) and the chemokine KC in the lung after TsV administration. Neutrophil influx was preceded by the production of KC and dependent on CXCR2, as shown by the ability of repertaxin, a CXCR2 inhibitor, to prevent an increase of MPO activity in the lung. Repertaxin had no effect on TsV-induced lethality. The PAFR antagonist (UK-74,505) significantly reduced TsV-induced vascular permeability changes and neutrophil influx in the lungs. The inhibition of neutrophil influx was associated with inhibition of the production of the CXCR2-active chemokine KC. UK-74,505 had no effect on the lethality induced by TsV. In conclusion, these results show that the influx of neutrophils in the lungs of mice injected with TsV is dependent on the activation of PAFR and on PAFR-dependent production of the chemokine KC as well as activation of CXCR2 on neutrophils. Although lung injury may contribute to late lethality after TsV envenoming, acute lethality is not modified by inhibitors of neutrophil influx.