Franco Capsoni

The neuropeptide α-MSH has specific receptors on neutrophils and reduces chemotaxis in vitro

Abstract The proopiomelanocortin-derived peptide α-melanocyte stimulating hormone (α-MSH) has potent anti-inflammatory effects in all animal models of inflammation against which it has been tested. Understanding of the mechanism by which this occurs is incomplete, although there is recent evidence for α-MSH receptors in murine and human macrophages and for modulation of production of proinflammatory cytokines and related mediators by α-MSH. Because of the prominence of neutrophils in early stages of inflammatory reactions where α-MSH is effective, we examined human neutrophils for evidence of mRNA for α-MSH receptors and for inhibition of neutrophil chemotaxis. There was accumulation of mRNA for melanocortin receptor 1 (MC1) in RT PCR product from neutrophils stimulated with interferon and LPS. In subsequent studies α-MSH inhibited migration of neutrophils from most normal volunteers when the cells were placed in FMLP or IL-8 gradients. The inhibition by α-MSH could be traced to alterations in cAMP in neutrophils. The presence of α-MSH receptor message in neutrophils is consistent with the established anti-inflammatory effects of the peptide. Direct inhibition of neutrophil chemotaxis likely contributes to the anti-inflammatory activity of α-MSH.

Autoimmunity and Anti‐TNF‐α Agents

Abstract: Treatment of rheumatoid arthritis (RA) patients with anti‐tumor necrosis factor‐alpha (anti‐TNF‐α) biologic agents has been associated with a reduction in the levels of specific autoantibodies, such as rheumatoid factor (RF) and anticyclic citrullinated peptide (anti‐CCP), and the induction of non‐ organ‐specific autoantibodies (antinuclear antibodies [ANAs], anti‐dsDNA, and antiphospholipid antibodies [aPLs]). The mechanisms by which the blockade of anti‐TNF‐α decreases the generation of specific autoantibodies, such as anti‐CCP and RF, are not yet known. However, it has been shown that these agents can downregulate the production of several inflammatory cytokines and mediators and that these anti‐inflammatory effects may account for reduced autoantibody generation, particularly in the synovial compartment. Infliximab treatment leads to the induction of ANAs in 63.8% of RA patients and 49.1% of Crohns disease (CD) patients, and anti‐dsDNA antibodies in 13% of RA patients and 21.5% of CD patients, respectively. The development of ANAs and anti‐dsDNA antibodies has also been described after etanercept therapy in 11% and 15% of RA patients, respectively. In the controlled trials, increases in ANA and anti‐dsDNA titers were observed in 5.3% and in 12.9% of adalimumab‐treated RA patients. Only limited data on the induction of aPL antibodies during TNF‐α blocking treatment are available.

Drug-induced lupus erythematosus.

RETRACTED

Primary and secondary autoimmune neutropenia

Antineutrophil antibodies are well recognized causes of neutropenia, producing both quantitative and qualitative defects in neutrophils and increased risk for infection. In primary autoimmune neutropenia (AIN) of infancy, a moderate to severe neutropenia is the sole abnormality; it is rarely associated with serious infections and exhibits a self-limited course. Chronic idiopathic neutropenia of adults is characterized by occurrence in late childhood or adulthood, greater prevalence among females than among males, and rare spontaneous remission. Secondary AIN is more commonly seen in adults and underlying causes include collagen disorders, drugs, viruses and lymphoproliferative disorders. In most patients with AIN, antibodies recognize antigens located on the IgG Fc receptor type 3b but other target antigens have been recently identified in secondary AIN. Granulocyte colony-stimulating factor is a proven treatment in patients with AIN of all types and is now preferred to other possible therapies.

IL‐10 up‐regulates human monocyte phagocytosis in the presence of IL‐4 and IFN‐γ

Interleukin‐10 (IL‐10), a cytokine produced by type 2 belper T (Th2) cells, inhibits the microbicidal effector function of interferon‐γ (EFN‐γ)‐activated macrophages. However, recent observations indicate that IL‐10, like IFN‐γ, increases FcγRI expression and FcγR‐mediated cytotoxic activity on human monocytes, suggesting that this cytokine cannot be classified purely as a monocyte deactivator. The present study found that incubation for 40 h of human monocytes or monocyte‐derived macrophages in the presence of EL‐10 caused a significant enhancement of their capacity to ingest particles coated with immunoglobulin G (FcγR‐mediated ingestion) or with C3b/C3bi fragments of the complement system (GR1/CR3‐mediated ingestion). The number of phagocytosing cells (% phagocytosis) and the number of ingested particles per cell (phagocytic index) were both significantly higher after 40‐h incubation of monocytes with IL‐10 concentrations ≥1 U/ml. This up‐regulating activity on phagocytosis was completely reversed by anti‐EL‐10 monoclonal antibody (mAb). As previously reported, ILIO stimulated FcγRI expression on monocytes but did not induce the expression of FcγRII, FcγRIII, CR1, and CR3. IFN‐γ, like EL‐10, up‐regulated only FcγRI expression but significantly reduced both FcγR‐ and CR‐mediated ingestion. IL‐10 almost completely reversed the IFN‐γ‐induced inhibition of both FcγR‐ and CR‐mediated phagocytosis, without concomitant changes in membrane expression of phagocytic receptors. Exposure of monocytes to IL‐4 reduced the membrane expression of all three FcγRs and also inhibited FcγR‐mediated ingestion. On the other hand, IL‐4 up‐regulated both CR3 expression and CR‐mediated ingestion on cultured monocytes. IL‐10 not only neutralized the down‐regulatory effect of IL‐4 on FcγR expression but also completely reversed the IL‐4‐induced suppression of FcγR‐mediated phagocytosis. Exposure of monocytes to a combination of IL‐10 and IL‐4 resulted in a synergistic effect on CR‐mediated ingestion, even though no additive effects were observed on CR membrane expression. Finally, culture of monocytes in medium containing anti‐EL‐10 mAb significantly reduced their capacity to ingest IgG‐ or C3b/C3bi‐coated particles, suggesting a role for endogenously produced IL‐10 in the modulation of phagocytosis by human monocytes. These results demonstrate that IL‐10 is a potent up‐regulator of the phagocytic activity of human mononuclear phagocytes and indicate that this function may be in sensitive balance with the relative concentrations of EL‐10, IL‐4, and IFN‐γ.

Interleukin-10 down-regulates oxidative metabolism and antibody-dependent cellular cytotoxicity of human neutrophils.

The authors investigated the ability of interleukin‐10 (IL‐10) to modulate some constitutive or interferon‐γ (IFN‐γ)‐enhanced activities of human neutrophils. An 18 h culture of neutrophils with IL‐10 dose‐dependently down‐regulated their capacity to produce O2− and lucigenin‐amplified chemiluminescence in response to n‐formyl‐methionyl‐leucylphenyl‐alanine (FMLP). Furthermore, treatment of neutrophils with IL‐10 decreased in a dose‐dependent fashion, their capacity to lyse antibody‐coated sheep erythrocytes. Membrane expression of FcγRI, FcγRII, FcγRIII, CR1, CR3 and FcγR‐ and CR‐mediated phagocytosis were not modified by the cytokine. Culture of neutrophils with IFN‐γ (100 U/ml) did not modify their FcγR‐ and CR‐mediated phagocytosis, but significantly up‐regulated FcγRI and CR3 membrane expression as well as their oxidative metabolism and antibody‐dependent cellular cytotoxicity (ADCC). When IL‐10 and IFN‐γ were added simultaneously to neutrophil culture, IL‐10 dose‐dependently reduced IFN‐γ‐induced increase of CR3 expression, O2− production (in response to both FMLP and phorbol 12‐myristate 13‐acetate, or PMA) and ADCC, but did not change FcγRI expression on phagocytes. These results demonstrate that IL‐10 is a significant neutrophil deactivator and provide new information on the role of IL‐10 in the regulation of neutrophil‐mediated inflammatory processes.

Induction of CD69 activation molecule on human neutrophils by GM-CSF, IFN-γ, and IFN-α

Abstract The CD69 glycoprotein is an early activation antigen of T and B lymphocytes but it expression is induced in vitro on cells of most hematopoietic lineages, including neutrophils after stimulation with PMA or fMLP. In this study, we investigated whether CD69 expression on human neutrophils could be modulated by inflammatory or anti-inflammatory cytokines (IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-18, G-CSF, GM-CSF, TNF-α, TGF-β, IFN-α, IFN-γ). Resting neutrophils from healthy subjects did not express CD69 on the cell surface; moreover, a preformed intracellular pool of CD69 was not evident in these cells. CD69 was barely detectable on these cells after overnight incubation in medium while overnight incubation with GM-CSF, IFN-γ or IFN-α significantly induced CD69 expression on neutrophils with GM-CSF appearing to be the most potent inducer. This induction was dependent on a new protein synthesis as it was significantly inhibited by cycloheximide (about 50% inhibition). CD69 cross-linking on GM-CSF-primed neutrophils sinergized with LPS and increased TNF-α production and secretion suggesting a role for CD69-positive neutrophils in the pathogenesis and maintenance of different inflammatory diseases.

Bisphosphonate-associated osteonecrosis of the jaw: the rheumatologist's role

Several recent reports have described osteonecrosis of the jaws (ONJ) associated with the use of bisphosphonates. Rheumatologists treating bone diseases with bisphosphonate need, therefore, to be aware of this potential risk and plan the prophylaxis, early diagnosis and prevention of potential consequences. We review the literature on this newly described complication, with particular focus on systemic and local predisposing pathologies, preventive measures suggested before and during therapy with bisphosphonates, and the most frequent clinical presentation of the oral lesions. The expert panel recommendations for the management of care of patients who develop ONJ are summarized.

Effect of adalimumab on neutrophil function in patients with rheumatoid arthritis

Neutrophils are known to be targets for the biological activity of tumour necrosis factor (TNF)-α in the pathogenensis of rheumatoid arthritis (RA). Therefore, these cells may be among the targets of anti-TNF-α therapy. In this study we evaluated the effect of therapy with adalimumab (a fully human anti-TNF-α mAb; dosage: 40 mg subcutaneously every other week) on certain phenotypic and functional aspects of neutrophils obtained from 10 selected patients with RA and 20 healthy control individuals. Peripheral blood neutrophils were obtained at baseline and during anti-TNF-α therapy (2, 6 and 12 weeks after the first administration of adalimumab). All patients had been receiving a stable regimen of hydroxychloroquine, methotrexate and prednisone for at least 3 months before and during the study. Baseline neutrophil chemotaxis was significantly decreased in RA patients when compared with control individuals (P < 0.001). Two weeks after the first administration of adalimumab, chemotactic activity was completely restored, with no differences noted between patients and control individuals; these normal values were confirmed 6 and 12 weeks after the start of anti-TNF-α therapy. Phagocytic activity and CD11b membrane expression on neutrophils were similar between RA patients and control individuals; no modifications were observed during TNF-α neutralization. The production of reactive oxygen species, both in resting and PMA (phorbol 12-myristate 13-acetate)-stimulated cells, was significantly higher in RA patients at baseline (P < 0.05) and was unmodified by anti-TNF-α mAb. Finally, we showed that the activation antigen CD69, which was absent on control neutrophils, was significantly expressed on neutrophils from RA patients at baseline (P < 0.001, versus control individuals); however, the molecule was barely detectable on cells obtained from RA patients during adalimumab therapy. Because CD69 potentially plays a role in the pathogenesis of arthritis, our findings suggest that neutrophils are among the targets of anti-TNF-α activity in RA and may provide an insight into a new and interesting mechanism of action of anti-TNF-α mAbs in the control of inflammatory arthritis.

A new simplified single-filter assay for "in vitro" evaluation of chemotaxis of 51Cr-labeled polymorphonuclear leukocytes

A new simplified radioassay for measuring polymorphonuclear leukocyte (PMN) chemotaxis is proposed using 51Cr-labeled cells and a single-filter system. The technique offers all the advantages described for the double-filter radioassay and permits a reproducible measurement of random locomotion, chemokinesis and chemotaxis. Moreover the single-filter radioassay utilizes commercially available and disposable chambers gathered in a multichamber apparatus; this makes the method very easy to learn and rapid to perform.