Claude Cuvelier

Attenuation of allergic airway inflammation in IL‐4 deficient mice

To investigate the role of IL‐4 in vivo in allergic asthma, we developed a murine model of allergen‐induced airway inflammation. Repealed daily exposures of actively immunised C57BL/6 mice to aerosolized ovalbumin (OVA) induced a peribronchial inflammation and an increase in eosinophils and lymphocytes in bronchoalveolar‐lavage(BAL) fluid. In IL‐4 deficient (IL4−/−) mice, treated in the same way, there were substantially fewer eosinophils in BAL and much less peribronchial inflammation compared with wild type mice. In this model, mast cell deficient (W/Wv) mice developed a similar degree of BAL eosinophilia and peribronchial inflammation as wild type mice, demonstrating that the mast cell is not required for the induction of chronic airway inflammation. In contrast, BAL eosinophilia and airway inflammation were absent in OVA‐treated MHC ClassII deficient (B6.Aa−/−) mice which lack mature CD4+ T lymphocytes. In conclusion, these results indicate that IL‐4 is a central mediator of allergic airway inflammation, regulating antigen‐induced eosinophil recruitment into the airways by a T cell dependent mechanism.

Nasal polyposis: from cytokines to growth.

Nasal polyposis (NP) is a chronic inflammatory condition that is mostly characterized by an infiltration of eosinophils. How this eosinophilic inflammation leads to polyp formation remains largely unclear. In order to identify the most important factors in polyp growth, first we report the histologic features of two early stage manifestations of eosinophilic nasal polyps compared to their surrounding normal mucosa and mature polyps from the same patients. Histomorphologic analysis of these early stage manifestations of NP showed the presence of eosinophils, forming a subepithelial cap over a pseudocyst area that was filled with albumin. In mature NP, a large pseudocyst area containing albumin was surrounded by subepithelial eosinophilia. Second, in an approach to quantify and to study possible relations between eosinophilic inflammation and changes in extracellular tissue components we measured interleukin-5 (IL-5), eotaxin, eosinophil cationic protein (ECP), leukotrienes (LTC4/D4/E4), transforming growth factor-β 1 (TGF-β1), fibronectin, hyaluronic acid, and albumin in nasal tissue homogenates of 31 subjects. Nasal polyp samples (n = 16) were obtained during routine endonasal sinus surgery, whereas control non-polyp samples (n = 15) from subjects with (6) and without (9) allergic rhinitis were obtained from the inferior turbinate during septum surgery. In the group of polyp patients 11 received no treatment, whereas 5 were treated with oral glucocorticoids (GCS) within 4 weeks before surgery. IL-5 was measurable in 8 of 11 untreated NP, whereas IL-5 could not be detected in all 15 controls nor in 4 of 5 oral corticoid-treated polyps. The comparison between the untreated polyp group and controls showed significantly higher concentrations of IL-5, eotaxin, ECP, and albumin in polyp supernatants, whereas TGF-β1 was significantly lower. In the oral GCS-treated group, ECP and albumin were significantly reduced compared to untreated nasal polyps. The same tendency, but not reaching significance, was seen for eotaxin and fibronectin, while no difference was found for LTC4/D4/E4 and hyaluronic acid between the groups. Our observations suggest a deposition of albumin (and possibly other plasma proteins) and extracellular matrix proteins, which may be regulated by the subepithelial eosinophilic inflammation, as a possible pathogenic principle of polyp formation and growth. IL-5 and eotaxin are found to be key factors for eosinophilic accumulation and activation in NP. Oral corticoid treatment may lead to the shrinkage of NP by downregulation of the eosinophilic inflammation and reduction of the extravasation and deposition of albumin in NP.

Caspase inhibition causes hyperacute tumor necrosis factor-induced shock via oxidative stress and phospholipase A2

Dysregulated apoptotic cell death contributes to many pathological conditions, including sepsis, prompting the suggestion that caspase inhibition to block apoptosis could have useful therapeutic applications. Because the cytokine tumor necrosis factor (TNF, also known as TNF-α) is both pro-apoptotic and pro-inflammatory and is involved in septic shock, we tested whether caspase inhibition would alleviate TNF-induced toxicity in vivo. General caspase inhibition by the protease inhibitor zVAD-fmk exacerbated TNF toxicity by enhancing oxidative stress and mitochondrial damage, resulting in hyperacute hemodynamic collapse, kidney failure and death. Thus, survival of TNF toxicity depends on caspase-dependent processes. Our results demonstrated the pathophysiological relevance of caspase-independent, ROS-mediated pathways in response to lethal TNF-induced shock in mice. In addition, survival of TNF toxicity seemed to require a caspase-dependent protective feedback on excessive reactive oxygen species (ROS) formation and phospholipase A2 activation.

Immunomodulatory effects of anti-tumor necrosis factor alpha therapy on synovium in spondylarthropathy: histologic findings in eight patients from an open-label pilot study.

OBJECTIVE To assess the effects of treatment with anti-tumor necrosis factor alpha (anti-TNFalpha) on synovial histology in patients with spondylarthropathy (SpA) in order to confirm the effect on peripheral synovitis and to investigate the immunologic mechanisms involved in anti-TNFalpha therapy. METHODS Patients with treatment-resistant SpA were treated with infliximab (5 mg/kg) at weeks 0, 2, and 6 in an open-label pilot study. In 8 patients, synovial biopsy tissues obtained at baseline, week 2, and week 12 were used for histologic and immunohistochemical evaluation. RESULTS In all 8 patients (3 with ankylosing spondylitis, 1 with undifferentiated SpA, and 4 with psoriatic arthritis), there was a clear clinical improvement in the peripheral arthritis after anti-TNFalpha therapy. Histologic analysis of the synovial biopsy tissues indicated that the synovial lining layer thickness tended to decrease, with a significant reduction of CD55+ synoviocytes, at week 12. In the sublining layer, vascularity was reduced at week 12, with a decreased endothelial expression of vascular cell adhesion molecule 1 but not intercellular adhesion molecule 1, platelet endothelial cell adhesion molecule 1, and E-selectin. Although at week 2 and week 12, the number of neutrophils and CD68+ macrophages in the sublining layer was decreased, the overall degree of inflammatory infiltration remained unchanged. This could be related to the lymphocyte infiltration since at week 12, only CD4+ cells (but not CD3+, CD45RO+, and CD8+ cells) tended to decrease, while CD20+ lymphocytes and plasma cells were clearly increased. CONCLUSION The reduction in lining layer thickness, vascularity, and infiltration with neutrophils and macrophages paralleled the beneficial effect of anti-TNFalpha therapy on peripheral synovitis in 8 patients with different subtypes of SpA. The adhesion molecule expression, T cell infiltration, and, most important, B cell infiltration seemed to contrast with previous observations in RA. Although these preliminary data need to be confirmed in a larger cohort, they suggest distinct immunomodulatory mechanisms of anti-TNFalpha in SpA.

Comparative study of the synovial histology in rheumatoid arthritis, spondyloarthropathy, and osteoarthritis: influence of disease duration and activity

OBJECTIVES To compare the macroscopic and microscopic characteristics of synovial tissue in rheumatoid arthritis (RA), spondyloarthropathy (SpA), and osteoarthritis (OA) after exclusion of possible biases induced by disease duration or activity, or both. METHODS Synovial biopsy specimens were obtained by needle arthroscopy in patients with early RA (n=16), late RA (n=14), early SpA (n=23), and OA (n=12). Macroscopic and microscopic features were scored on a four point scale and analysed as a function of disease duration (early versus late RA), local and systemic disease activity, and diagnosis. RESULTS Except for the maximal synovial lining thickness, no significant differences were seen between early and late RA. For disease activity, synovial histology was only weakly correlated with C reactive protein in RA, but seemed to be strongly dependent on effusion of the biopsied joint in all disease groups. After stratification for local disease activity, no disease related differences were found in patients without joint effusion. In contrast, important differences were found between patients with RA and SpA with active joint effusion. Synovial vascularity was macroscopically increased in SpA versus RA (p=0.017). A straight vessel pattern was only seen in RA, while tortuous vessels were preferentially seen in SpA. Vascularity was also microscopically increased in SpA compared with RA (p=0.031), and correlated with the macroscopic vascularity (rs =0.36, p=0.036). CD3+ (p=0.008), CD4+ (p=0.008), and CD20+ (p=0.024) lymphocytes were overrepresented in RA compared with SpA. The integrin expression in RA was characterised by a decrease of αVβ3 in the synovial lining (p=0.006) and an increase of αVβ5 in the sublining (p<0.001). CONCLUSIONS The immune architecture of the synovial membrane is more dependent on local disease activity than on disease duration. Synovium obtained from clinically affected joints shows important histological differences between RA and SpA.

Organization of secondary lymphoid tissue and local IgE formation to Staphylococcus aureus enterotoxins in nasal polyp tissue

Background:  Bilateral nasal polyposis (NP) is characterized by high concentrations of IgE in NP tissue, which show no relation to the atopic status. We aimed to study the relationship between systemic and local IgE formation, nasal carriage of Staphylococcus aureus and nasal polyposis.

Reduced amounts and abnormal forms of phospholipase C zeta (PLCzeta) in spermatozoa from infertile men.

BACKGROUND In mammals, oocyte activation at fertilization is thought to be induced by the sperm-specific phospholipase C zeta (PLCzeta). However, it still remains to be conclusively shown that PLCzeta is the endogenous agent of oocyte activation. Some types of human infertility appear to be caused by failure of the sperm to activate and this may be due to specific defects in PLCzeta. METHODS AND RESULTS Immunofluorescence studies showed PLCzeta to be localized in the equatorial region of sperm from fertile men, but sperm deficient in oocyte activation exhibited no specific signal in this same region. Immunoblot analysis revealed reduced amounts of PLCzeta in sperm from infertile men, and in some cases, the presence of an abnormally low molecular weight form of PLCzeta. In one non-globozoospermic case, DNA analysis identified a point mutation in the PLCzeta gene that leads to a significant amino acid change in the catalytic region of the protein. Structural modelling suggested that this defect may have important effects upon the structure and function of the PLCzeta protein. cRNA corresponding to mutant PLCzeta failed to induce calcium oscillations when microinjected into mouse oocytes. Injection of infertile human sperm into mouse oocytes failed to activate the oocyte or trigger calcium oscillations. Injection of such infertile sperm followed by two calcium pulses, induced by assisted oocyte activation, activated the oocytes without inducing the typical pattern of calcium oscillations. CONCLUSIONS Our findings illustrate the importance of PLCzeta during fertilization and suggest that mutant forms of PLCzeta may underlie certain types of human male infertility.

Macrophages expressing the scavenger receptor CD163: a link between immune alterations of the gut and synovial inflammation in spondyloarthropathy.

The objective of this study was to investigate CD163+ macrophages in the synovial membrane of patients with spondyloarthropathy (SpA). Immunohistochemistry was performed on synovium of 17 SpA and 18 rheumatoid arthritis (RA) patients, on colonic biopsies of 16 SpA patients and ten healthy controls, and on paired synovial biopsies of eight SpA patients, before and after anti‐TNFα therapy. Phenotype and cytokine production were analysed by flow cytometry. CD163+ macrophages were increased in the synovial lining and sublining in SpA versus RA, as well as in colonic lamina propria in SpA versus controls. The number of CD163+ macrophages in the synovial sublining correlated with C‐reactive protein levels and erythrocyte sedimentation rate. Paralleling the increase of CD163, HLA‐DR was increased in the synovial lining and sublining of SpA. In contrast, the co‐stimulatory molecules CD80 and CD86 and the dendritic cell markers CD1a and CD83 were scarce in SpA synovium. Flow cytometry indicated that CD163+ macrophages expressed high levels of HLA‐DR and could produce in vitro tumour necrosis factor α (TNFα) but not interleukin‐10 (IL‐10). Finally, anti‐TNFα therapy in vivo induced a decrease of CD163+ macrophages in the synovial lining and sublining. In conclusion, macrophages expressing the scavenger receptor CD163 are increased in synovium and in colonic mucosa in SpA, highlighting the relationship between joint and gut in this disease. The correlation with inflammatory parameters, the expression of HLA‐DR, the production of TNFα but not IL‐10, and the reduction by anti‐TNFα therapy support a role for CD163+ macrophages in the synovial inflammation in SpA. Copyright

Orally administered L. lactis secreting an anti-TNF Nanobody demonstrate efficacy in chronic colitis

Inflammatory bowel disease (IBD) is a chronic inflammatory gastrointestinal disorder. Systemic treatment of IBD patients with anti-tumor necrosis factor (TNF)-α antibodies has proven to be a highly promising approach, but several drawbacks remain, including side effects related to systemic administration and high cost of treatment. Lactococcus lactis was engineered to secrete monovalent and bivalent murine (m)TNF-neutralizing Nanobodies as therapeutic proteins. These therapeutic proteins are derived from fragments of heavy-chain camelid antibodies and are more stable than conventional antibodies. L. lactis-secreted anti-mTNF Nanobodies neutralized mTNF in vitro. Daily oral administration of Nanobody-secreting L. lactis resulted in local delivery of anti-mTNF Nanobodies at the colon and significantly reduced inflammation in mice with dextran sulfate sodium (DSS)-induced chronic colitis. In addition, this approach was also successful in improving established enterocolitis in interleukin 10 (IL10)–/– mice. Finally, L. lactis-secreted anti-mTNF Nanobodies did not interfere with systemic Salmonella infection in colitic IL10–/– mice.In conclusion, this report details a new therapeutic approach for treatment of chronic colitis, involving in situ secretion of anti-mTNF Nanobodies by orally administered L. lactis bacteria. Therapeutic application of these engineered bacteria could eventually lead to more effective and safer management of IBD in humans.

TGF-β signaling and collagen deposition in chronic rhinosinusitis

BACKGROUND Chronic rhinosinusitis is an inflammatory disease with distinct cytokine and remodeling patterns. OBJECTIVE The objective was to analyze the presence of TGF-beta isoforms, receptors, intracellular signaling, and collagen deposition in chronic rhinosinusitis. METHODS Sinonasal mucosal samples obtained from chronic rhinosinusitis with nasal polyps (CRSwNP; n = 13), chronic rhinosinusitis without nasal polyps (CRSsNP; n = 13), and controls (n = 10) were analyzed for TGF-beta isoforms 1 and 2 by means of ELISA and IHC, and for TGF-beta R1, 2, and 3 by RT-PCR and IHC. As downstream proteins, phospho-Smad 2 (pSmad 2) and collagen were analyzed by performing immunostaining and picrosirius red staining, respectively. RESULTS TGF-beta 1 and 2 protein concentrations, TGF-beta receptor (R) I and TGF-beta RIII mRNA expression, the number of pSmad 2-positive cells, and total collagen amount were significantly higher in CRSsNP versus controls. In CRSwNP, TGF-beta 1 protein concentration, TGF-beta RII and TGF-beta RIII mRNA expression, the number of pSmad 2-positive cells, and total collagen amount were significantly lower versus controls. Only TGF-beta 2 protein was found higher in CRSwNP versus controls. CONCLUSION A high TGF-beta 1 protein expression, increased TGF-beta RI expression, and a high number of pSmad 2-positive cells all indicate an enhanced TGF-beta signaling in CRSsNP, whereas a low TGF-beta 1 protein concentration, a decreased expression of TGF-beta RII, and a low number of pSmad 2-positive cells in CRSwNP indicate a low level of TGF-beta signaling in CRSwNP. These findings are compatible with the remodeling patterns observed, reflected by a lack of collagen in CRSwNP, and excessive collagen production with thickening of the collagen fibers in the extracellular matrix in CRSsNP.