Study of the Role of the Tyrosine Kinase Receptor MerTK in the Development of Kidney Ischemia-Reperfusion Injury in RCS Rats.

Renal ischaemia reperfusion (I/R) triggers a cascade of events including oxidative stress, apoptotic body and microparticle (MP) formation as well as an acute inflammatory process that may contribute to organ failure. Macrophages are recruited to phagocytose cell debris and MPs. The tyrosine kinase receptor MerTK is a major player in the phagocytosis process. Experimental models of renal I/R events are of major importance for identifying I/R key players and for elaborating novel therapeutical approaches. A major aim of our study was to investigate possible involvement of MerTK in renal I/R. We performed our study on both natural mutant rats for MerTK (referred to as RCS) and on wild type rats referred to as WT. I/R was established by of bilateral clamping of the renal pedicles for 30' followed by three days of reperfusion. Plasma samples were analysed for creatinine, aspartate aminotransferase (ASAT), lactate dehydrogenase (LDH), kidney injury molecule -1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) levels and for MPs. Kidney tissue damage and CD68-positive cell requirement were analysed by histochemistry. monocyte chemoattractant protein-1 (MCP-1), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS), and histone 3A (H3A) levels in kidney tissue lysates were analysed by western blotting. The phagocytic activity of blood-isolated monocytes collected from RCS or WT towards annexin-V positive bodies derived from cultured renal cell was assessed by fluorescence-activated single cell sorting (FACS) and confocal microscopy analyses. The renal I/R model for RCS rat described for the first time here paves the way for further investigations of MerTK-dependent events in renal tissue injury and repair mechanisms.

High-Fat Diet-Induced IL-17A Exacerbates Psoriasiform Dermatitis in a Mouse Model of Steatohepatitis.

Recent studies suggest that psoriasis may be more severe in patients with nonalcoholic fatty liver disease, particularly in those with the inflammatory stage of steatohepatitis [nonalcoholic steatohepatitis (NASH)]. Herein, we investigated the impact of diet-induced steatohepatitis on the severity of imiquimod-induced psoriasiform dermatitis. Mice fed with a high-fat diet developed steatohepatitis reminiscent of human NASH with ballooning hepatocytes and significant liver fibrosis. Mice with steatohepatitis also displayed moderate cutaneous inflammation characterized by erythema, dermal infiltrates of CD45(+) leukocytes, and a local production of IL-17A. Moreover, steatohepatitis was associated with an epidermal activation of caspase-1 and cutaneous overexpression of IL-1ß. Imiquimod-induced psoriasiform dermatitis was exacerbated in mice with steatohepatitis as compared to animals fed with a standard diet. Scale formation and acanthosis were aggravated, in correlation with increased IL-17A and IL-22 expression in inflamed skins. Finally, intradermal injection of IL-17A in standard diet-fed mice recapitulated the cutaneous pathology of mice with steatohepatitis. The results show that high-fat diet-induced steatohepatitis aggravates the inflammation in psoriasiform dermatitis, via the cutaneous production of IL-17A. In agreement with clinical data, this description of a novel extrahepatic manifestation of NASH should sensitize dermatologists to the screening and the management of fatty liver in psoriatic patients.

Ex vivo PBMC cytokine profile in familial Mediterranean fever patients: Involvement of IL-1ß, IL-1α and Th17-associated cytokines and decrease of Th1 and Th2 cytokines.

In order to clarify the inflammatory mechanism underlying familial Mediterranean fever (FMF), we aimed to evaluate the ex vivo cytokine profile of FMF patients during acute attacks and attack-free periods, and compare it with that of healthy controls. The study included 34 FMF patients, of whom 9 were studied during attack and remission and 24 healthy controls. Cytokine levels were evaluated by Luminex technology in serum and supernatants of PBMC (Peripheral Blood Mononuclear Cells) cultures with and without 24h stimulation of monocytes by LPS and T lymphocytes by anti-CD3/CD28 beads. Levels of IL-6 and TNF-α were higher in unstimulated and LPS-stimulated PBMC supernatants of FMF patients in crises compared to controls. In response to LPS stimulation, higher levels of IL-1ß and IL-1α were found in PBMC supernatants of patients during crises compared to those in remission and to controls. IFN-γ and IL-4 levels were the lowest in unstimulated and anti-CD3/CD28 stimulated PBMCs supernatants of patients during crises compared to remission and controls. The Th17 cytokines IL-17 and IL-22 were respectively higher in anti-CD3/CD28 stimulated PBMC supernatants of FMF patients during and between crises compared to controls. Amongst cytokines tested in serum, only IL-6 and TNFα were enhanced in FMF patients. The ex vivo study represents an interesting approach to evaluate cytokines' involvement in FMF. Our results suggest an ongoing subclinical inflammation and define an elevated inflammatory cytokine signature, distinctly for M694V homozygous patients. The absence of spontaneous IL-1ß release by PBMCs reflects no constitutive activation of the inflammasome in FMF physiopathology.

High plasma levels of the pro-inflammatory cytokine IL-22 and the anti-inflammatory cytokines IL-10 and IL-1ra in acute pancreatitis.

BACKGROUND/OBJECTIVES: Pancreatic acinar cells are major targets of IL-22. Our aim is to study early plasma levels of IL-22, of pro- and anti-inflammatory cytokines in acute pancreatitis, and their association with severity or necrosis infection. METHODS: Consecutive patients admitted to the Department of Hepato-Gastroenterology at Poitiers University of Medicine Hospital (France) with a diagnosis of AP were prospectively enrolled. Plasma concentrations of IL-22, IL-6, IL-8, IL-1 α, IL-1ß, TNF- α, IFN-γ, IL-17A, IL-10, IL-1ra and IL-4 were assessed by multiple immunoassay at the admission time. A thoracoabdominal contrast-enhanced CT scan was performed at day 2. RESULTS: Sixty-two patients were included; 13 patients (21%) had a severe acute pancreatitis, 5 patients (8%) developed necrosis infection and 29 patients (47%) had pleural effusion. Plasma levels of IL-22 were high in AP (135 ± 31 vs 4.2 ± 1.8 pg/ml for controls, p < 0.05), but did not correlate with the severity of the disease, whereas IL-6, IL-10 and IL-1ra where enhanced in patients with severe acute pancreatitis and with pleural effusion. Patients who further developed necrosis infection had higher levels of IL-1ra at admission (p = 0.0004). CONCLUSION: In acute pancreatitis, high plasma levels of IL-22 are observed, regardless the severity of the disease. In contrast, severe forms were associated with increased levels of IL-6, IL-10 and IL-1ra. The beneficial or deleterious role of IL-22 in AP remains to be further studied.

Liposomal co-encapsulation of a novel gemini lipopeptide and a CpG-ODN induces a strong Th1 response with the co-activation of a Th2/Th17 profile and high antibody levels.

A successful vaccine depends on its capacity to elicit a protective immune response against the target pathogen. The adjuvant used plays an important role in enhancing and directing the immune response. Liposomes are vaccine adjuvants that allow the co-encapsulation of antigens and immunostimulants. Our aim was to evaluate the adjuvanticity of a cationic liposome (Lip) formulated with a novel gemini lipopeptide (AG2-C16) alone or in combination with CpG-ODN as immunostimulants. To achieve this, we used the recombinant clumping factor of Staphylococcus aureus (rClfA) as a model antigen, in a murine model. We characterized the formulations by DLS, Cryo-SEM, and TEM, and analyzed the humoral and cellular immune responses induced in BALB/c and C57BL/6J mice injected with free rClfA and three formulations: Lip + CpG-ODN + rClfA, Lip + AG2-C16 + rClfA and Lip + AG2-C16 + CpG-ODN + rClfA. The addition of immunostimulants to the liposomes did not change the membrane diameter but affected their hydrodynamic diameter, z-potential, and homogeneity. All liposomal formulations were able to stimulate a specific humoral response, with high serum IgG, IgG1 and IgG2a or IgG2c titers in BALB/c or C57BL/6J mice, respectively. In addition, increased vaginal IgG levels were detected after injection, with no specific IgA. The cellular immunity induced by Lip + AG2-C16 + CpG-ODN + rClfA was characterized by a predominant Th1 profile, with the co-induction of Th2 and Th17 cells, and IFN-γ+ cytotoxic T cells. Furthermore, we studied the capacity of the different formulations to stimulate murine keratinocytes and fibroblasts in vitro. While no formulation activated keratinocytes, Lip + AG2-C16 + CpG-ODN increased the expression of CXCL9 in fibroblasts. These results suggest Lip + AG2-C16 + CpG-ODN as a promising adjuvant candidate to be used in vaccines against pathogens that require Th1/Th2/Th17 combined profiles, like S. aureus. Additionally, based on the IFN-γ+ cytotoxic T cells stimulation and the CXCL9 production by fibroblasts, we propose the use of this adjuvant formulation for the stimulation of a Th1 profile.

Salivary metabolome indicates a shift in tyrosine metabolism in patients with burning mouth syndrome: a prospective case-control study.

ABSTRACT: The pathophysiology of primary burning mouth syndrome (BMS) remains controversial. Targeted analyses or "omics" approach of saliva provide diagnostic or pathophysiological biomarkers. This pilot study's primary objective was to explore the pathophysiology of BMS through a comparative analysis of the salivary metabolome among 26 BMS female cases and 25 age- and sex-matched control subjects. Secondary objectives included comparative analyses of inflammatory cytokines, neuroinflammatory markers, and steroid hormones among cases and control subjects, and among BMS patients according to their clinical characteristics. Salivary metabolome, neuroinflammatory markers, cytokines, and steroids were, respectively, analysed by liquid chromatography coupled with mass spectrometry, ELISA and protease activity assay, and multiparametric Luminex method. Among the 166 detected metabolites, univariate analysis did not find any discriminant metabolite between groups. Supervised multivariate analysis divided patients into 2 groups with an accuracy of 60% but did not allow significant discrimination (permutation test, P = 0.35). Among the metabolites contributing to the model, 3 belonging to the tyrosine pathway ( l -dopa, l -tyrosine, and tyramine) were involved in the discrimination between cases and control subjects, and among BMS patients according to their levels of pain. Among the detectable molecules, levels of cytokines, steroid hormones, and neuroinflammatory markers did not differ between cases and control subjects and were not associated with characteristics of BMS patients. These results do not support the involvement of steroid hormones, inflammatory cytokines, or inflammatory neurogenic mediators in the pathophysiology of pain in BMS, whereas the observed shift in tyrosine metabolism may indicate an adaptative response to chronic pain or an impaired dopaminergic transmission.

Role of interleukin-1ß in NLRP12-associated autoinflammatory disorders and resistance to anti-interleukin-1 therapy.

OBJECTIVE: A new class of autoinflammatory syndromes called NLRP12-associated disorders (NLRP12AD) has been associated with mutations in NLRP12. Conflicting data on the putative role of NLRP12 in interleukin-1ß (IL-1ß) signaling have been found in in vitro analyses. This prospective study was undertaken to assess the secretion of IL-1ß and 3 IL-1ß-induced cytokines (IL-1 receptor antagonist [IL-1Ra], IL-6, and tumor necrosis factor α [TNFα]) in patients' peripheral blood mononuclear cells (PBMCs) cultured ex vivo and to evaluate the patients' response to IL-1Ra (anakinra), a major drug used in the treatment of autoinflammatory disorders. METHODS: Patients' disease manifestations and cytokine measurements were recorded before anakinra treatment was started, during 14 months of therapy, and after discontinuation of anakinra treatment. RESULTS: Spontaneous secretion of IL-1ß by patients' PBMCs was found to be dramatically increased (80-175 fold) compared to healthy controls. Consistent with these findings, anakinra initially led to a marked clinical improvement and to a rapid near-normalization of IL-1ß secretion. However, a progressive clinical relapse occurred secondarily, associated with an increase in TNFα secretion, persistent elevated levels of IL-1Ra and IL-6, and a reactivation of IL-1ß secretion. Anakinra was discontinued after 14 months of therapy. CONCLUSION: Our findings provide in vivo evidence of the crucial role of IL-1ß in the pathophysiology of NLRP12AD. This is the first time anakinra has been used to treat this disorder. This study provides new insights into the mechanisms underlying resistance to anti-IL-1 therapy observed in a few patients with autoinflammatory syndromes. Our data also point to the potential of ex vivo cytokine measurements as predictors of response to treatment.

Phenotype and cytokine profile in a TRAPS Syndrome family with TNFRSF1A p.(Thr79Met): Association with sacro-iliitis.

OBJECTIVE: A comparative retrospective and analytic study was performed in 13 members of a family, affected or not by tumor necrosis factor TNF-α receptor-associated periodic syndrome (TRAPS), including one patient with sacro-illitis. METHODS: Clinical features and TNFRSF1A gene analysis were reported for each family member, symptomatic or asymptomatic. Biological features including CRP/SAA, IgD and ex vivo T lymphocytes and myeloid-derived cytokine profile (IL1-ß, IL-1α, IL-1ra, IL-4, IL-10, IL-17, IFN-γ, TNF-α, IL-6) were characterized for all family members. CRP and IgD only were compared with those of 13 axial SA patients with TNF-blockade indication. RESULTS: Symptomatic TRAPS patients presented p.(Thr79Met) variant and generally complained of abdominal pain. They displayed higher SAA/IgD levels and IL-6/IL-1RA/IL-10 production by PBMC compared to asymptomatic family members. IgD serum level was higher in symptomatic members compared to SA patients. The patient with sacro-iliitis displayed the highest cytokine production and IgD serum levels. CONCLUSION: This study describes clinical heterogeneity in a family examined for TRAPS syndrome and reports the first sacro-iliitis in a patient with pathogenic TNFRSF1A variant. Dysregulated PBMC-derived cytokine and Il-10/IgD dysregulation in the patient with sacro-iliitis raises the issue of sacro-iliitis pathophysiology.

Ex vivo cytokine production in psoriatic disease: Towards specific signatures in cutaneous psoriasis and peripheral psoriatic arthritis.

Objectives: Psoriatic arthritis (PsA) and cutaneous psoriasis (PsO) are different phenotypes of psoriatic disease (PsD), whose underlying specific mechanisms remain incompletely understood. As cytokines are key elements to induce and tune up immune responses to drive inflammatory diseases, our objective was to assess whether clinical features, disease phenotype and PsA and PsO activity were associated with a particular ex vivo cytokine production profile. Methods: Forty-eight patients (37 PsA and 11 PsO) and 11 healthy subjects (HS) were studied. Cytokine production by peripheral blood mononuclear cells (PBMC) that were either unstimulated, or stimulated with LPS or anti-CD3/CD28 antibodies, were analysed by multiplex assay in the culture supernatants. Results: Cytokine signature of PsD includes a high level of TNFα in supernatants of LPS-stimulated PBMC, higher levels of IL-6 and lower levels of IFN-γ and IL-17A after CD3-CD28 stimulation, as well as higher spontaneous IL-1RA and TNFα production compared to HS. High body mass index (BMI) was associated with lower levels of IL-1ß, and metabolic syndrome with lower levels of IFN-γ after LPS stimulation. In PsD, dermatological activity was related with higher IL-17A level, while rheumatic activity was linked with lower levels of IFN-γ and TNFα. Comparing each PsD subtype to HS, IL-1ß and IL-6 productions are higher when using LPS stimulation in PsO patients with higher levels of IL-1ß and IL-1α in peripheral PsA patients after CD3/CD28 stimulation. LPS stimulation induced high levels of IL-17A in peripheral PsA compared to axial PsA. PsA patients with axial PsA share some features with PsO but shows a distinct cytokine pattern compared to peripheral PsA. Conclusion: PsO and the different PsA subtypes exhibit distinct ex vivo cytokine production profiles and common features of the so-called PsD. Analysis of IL-1 cytokine family and IL-6 seems to be of particular interest to distinguish PsO and peripheral PsA since it depends on monocytes in PsO and T-lymphocytes in peripheral PsA. Peripheral cytokine profiles are influenced by rheumatic and dermatological activity of the disease, and also by metabolic syndrome features. Our results highlight the crucial role of immune cell interactions with different patterns of interaction depending on clinical phenotype.

Design, synthesis and biological evaluation of new thalidomide analogues as TNF-α and IL-6 production inhibitors.

Several thalidomide analogues were synthesized and compared to thalidomide and its more active analogue, lenalidomide, for their ability to inhibit the production of the pro-inflammatory cytokine tumour necrosis factor (TNF)-α and interleukin (IL)-6 by LPS-activated peripheral blood mononuclear cells (PBMCs). Among these compounds, two analogues containing sulfonyl group displayed interesting downregulation of TNF-α and IL-6 production.

Cytokine Signature in Schnitzler Syndrome: Proinflammatory Cytokine Production Associated to Th Suppression.

Background: Schnitzler syndrome (SchS) is a rare autoinflammatory disease characterized by urticarial exanthema, bone and joint alterations, fever and monoclonal IgM gammopathy. Overactivation of the interleukin(IL)-1 system is reported, even though the exact pathophysiological pathways remain unknown. Objective: To determine ex vivo cytokine profiles of Peripheral Blood Mononuclear Cells (PBMCs) from SchS patients prior to treatment and after initiation of anti-IL-1 therapy (anakinra). The sera cytokine profile was studied in parallel. Methods: We collected blood samples from thirty-six untreated or treated SchS. PBMCs were cultured with and without LPS or anti-CD3/CD28. Cytokine levels were evaluated in serum and cell culture supernatants using Luminex technology. Results: Spontaneous TNFα, IL-6, IL-1ß, IL-1α, and IL-1RA release by PBMCs of SchS patients were higher than in controls. LPS-stimulation further induced the secretion of these cytokines. In contrast, after T-cell stimulation, TNFα, IL-10, IFNγ, IL-17A, and IL-4 production decreased in SchS patients compared to healthy controls, but less in treated patients. Whereas IL-1ß serum level was not detected in most sera, IL-6, IL-10, and TNFα serum levels were higher in patients with SchS and IFNγ and IL-4 levels were lower. Of note, IL-6 decreased after treatment in SchS (p = 0.04). Conclusion: Our data strengthen the hypothesis of myeloid inflammation in SchS, mediated in particular by IL-1ß, TNFα, and IL-6, associated with overproduction of the inhibitors IL-1RA and IL-10. In contrast, we observed a loss of Th1, Th2, and Th17 cell functionalities that tends to be reversed by anakinra.

Skin inflammatory response and efficacy of anti-epidermal growth factor receptor therapy in metastatic colorectal cancer (CUTACETUX).

Anti-epidermal growth factor receptor (EGFR) monoclonal antibody is a standard treatment of metastatic colorectal cancer (mCRC) and its most common adverse effect is a papulopustular acneiform rash. The aim of the CUTACETUX study was to characterize the skin inflammatory response associated with this rash and its relation to treatment efficacy. This prospective study included patients with mCRC treated with first-line chemotherapy plus cetuximab. Patients underwent skin biopsies before the initiation of cetuximab (D0) and before the third infusion (D28), one in a rash zone and one in an unaffected zone. Expression of Th17-related cytokines (IL-17A, IL-21, IL-22), antimicrobial peptides (S100A7 and BD-2), innate response-related cytokines (IL-1ß, IL-6, TNF-α and OSM), T-reg-related cytokines (IL-10 and TGF-ß), Th1-related cytokine (IFN-γ), Th2-related cytokine (IL-4), Thymic stromal lymphopoietin and keratinocyte-derived cytokines (IL-8, IL-23 and CCL20) were determined by RT-PCR. Twenty-seven patients were included. Levels of most of the cytokines increased at D28 in the rash zone compared to D0. No significant association was observed between variations of cytokines levels and treatment response in the rash zone and only the increase of IL-4 (p = .04) and IL-23 (p = .02) levels between D0 and D28 in the unaffected zone was significantly associated with treatment response. Increased levels of IL-8 (p = .02), BD-2 (p = .02), IL-1ß (p = .004) and OSM (p = .02) in the rash zone were associated with longer progression-free survival. Expression of Th2-related and keratinocyte-derived cytokines in the skin was associated with anti-EGFR efficacy. If this inflammatory signature can explain the rash, the exact mechanism by which these cytokines are involved in anti-EGFR tumor response remains to be studied.

Molecular and functional characterization of a new potassium conductance in mouse ventricular fibroblasts.

The present work is aimed at identifying and characterizing, at a molecular and functional level, new ionic conductances potentially involved in the excitation-secretion coupling and proliferation of cardiac ventricular fibroblasts. Among potassium channel transcripts which were screened by high-throughput real-time PCR, SUR2 and Kir6.1 mRNAs were found to be the most abundant in ventricular fibroblasts. The corresponding proteins were not detected by western blot following 5 days of cell culture, but had appeared at 7 days, increasing with extended cell culture duration as the fibroblasts differentiated into myofibroblasts. Using the inside-out configuration of the patch-clamp technique, single potassium channels could be recorded. These had properties similar to those reported for SUR2/Kir6.1 channels, i.e. activation by pinacidil, inhibition by glibenclamide and activation by intracellular UDP. As already reported for this molecular signature, they were insensitive to intracellular ATP. In the whole-cell configuration, these channels have been shown to be responsible for a glibenclamide-sensitive macroscopic potassium current which can be activated not only by pinacidil, but also by nanomolar concentrations of the sphingolipid sphingosine-1-phosphate (S1P). The activation of this current resulted in an increase in cell proliferation and a decrease in IL-6 secretion, suggesting it has a functional role in situations where S1P increases. Overall, this work demonstrates for the first time that SUR2/Kir6.1 channels represent a significant potassium conductance in ventricular fibroblasts which may be activated in physio-pathological conditions and which may impact on fibroblast proliferation and function.

Characterization of skin Th17 transcriptional profiles in psoriatic patients under adalimumab biotherapy.

In psoriasis, a specific cytokine network has been described to play a central role in the pathophysiology of the disease. Anti-cytokine therapeutic approaches have been largely developed and TNFα constitutes the main target. Adalimumab is a human anti-TNFα monoclonal antibody that has been reported to demonstrate clinical efficacy and safety, resulting in reversal of epidermal hyperplasia and cutaneous inflammation. We aimed to analyse changes in the skin inflammatory transcriptomic profile in psoriatic patients during adalimumab therapy. In addition, the circulating cytokine profile was analysed to define systemic inflammation. Eighteen patients with chronic plaque psoriasis were treated with adalimumab. After four and 16 weeks, clinical efficacy was assessed using PASI and DLQI, and skin mRNA profiles were determined and circulating cytokines quantified. We identified a rapid effect of adalimumab therapy on a large array of Th17 cytokines of the skin, which may account for the modification of keratinocyte expression profile and clinical response. In contrast, analysis of serum cytokine concentrations was uninformative, confirming the need for characterization of local cytokines in skin lesions. Finally, in non-responders, local cytokine expression was shown to be unchanged. We show that TNFα inhibition in psoriasis patients treated with adalimumab has a broad effect on the expression profile of cytokines and keratinocyte markers of skin inflammation, which may account for its clinical efficacy.

Cyclosporin A inhibition of macrophage colony-stimulating factor (M-CSF) production by activated human T lymphocytes.

M-CSF is a pleiotropic cytokine involved in the survival, proliferation, and differentiation of cells of the monocyte/macrophage lineage. M-CSF is produced by numerous cells including CD3-activated T cells. M-CSF serum levels are increased during acute graft rejection. We tested the in vitro production of M-CSF, GM-CSF, IL-2, and IL-4 by T-cell clones costimulated by CD3 and accessory activation pathways and the effects of cyclosporin A and methylprednisolone. The nine clones studied and CD4+ cells purified from peripheral blood mononuclear cells (PBMC) spontaneously produced low levels of M-CSF, which PMA and CD3 mAb strongly enhanced. In contrast to IL-2, CD28 mAb did not further enhance this production. CsA inhibited M-CSF production by clones and purified CD4 T cells. Addition of IL-2, anti IL-2, or anti CD25 mAb to the cultures demonstrated that CsA down-regulated M-CSF synthesis by activated T cells through its inhibition of IL-2 synthesis. These results could help to better understand the complex mechanisms of acute graft rejection and immunosuppression.

Specific increase in caspase-1 activity and secretion of IL-1 family cytokines: a putative link between mevalonate kinase deficiency and inflammation.

The mevalonate kinase deficiency (MKD), including hyperimmunoglobulinemia D periodic fever syndrome (HIDS) and the more severe mevalonic aciduria are rare, autosomal recessive, autoinflammatory diseases belonging to the hereditary periodic fever (HPF) family. Other members include: familial mediterranean fever (FMF), the cryopyrin-associated periodic syndromes (CAPS) and TNFR-associated periodic syndromes (TRAPS). MKD is caused by mutations in the gene encoding mevalonate kinase (MK), an enzyme of the cholesterol pathway, leading to its inactivation. The molecular mechanisms linking MKD and abnormalities of isoprenoid biosynthesis to cytokine production and inflammation have yet to be fully elucidated. Statins, which are extensively prescribed for lowering cholesterol, are potent inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, the enzyme directly upstream of MK. In this review, we discuss recent reports demonstrating that in vitro inhibition of the mevalonate pathway by statins specifically increases the production, by activated monocytes, of cytokines of the IL-1 family, by enhancing caspase-1 activity, the enzyme responsible for IL-1beta and IL-18 maturation. The molecular mechanisms involve geranylgeranylation and the enhancement of the activity of G proteins such as Rac-1. Interestingly, activated fibroblasts from MKD patients secrete more IL-1beta than fibroblasts from healthy donors. Taken together, these data highlight the specific enhancement of the IL-1 family of cytokines, the maturation of which is caspase-1-dependent in MKD. Finally, the spectacular decrease in febrile attacks in patients with severe HIDS under IL-1 receptor antagonist (anakinra) treatment, reinforces this hypothesis. Deregulated caspase-1 activation could be responsible for the inflammatory component of MKD, thereby mechanistically linking MKD to FMF and CAPS through cytokines of the IL-1 family.

Pharmacological inhibitors of the mevalonate pathway activate pro-IL-1 processing and IL-1 release by human monocytes.

OBJECTIVE: The effects of statins (3-hydroxy-3-methylglutaryl coenzyme A reductase-HMGR-inhibitors) on the inflammatory response remain unclear. HMGR is implicated in the mevalonate pathway, directly upstream of cholesterol biosynthesis. We studied the impairment by this pathway of cytokine production by peripheral blood mononuclear cells (PBMCs) and THP-1 cells. The aim was to identify a specific cytokine "signature" of cells under simvastatin treatment in order to link pharmacological inhibition of the mevalonate pathway and inflammation. METHODS: Normal human PBMCs and THP-1 cells were cultured with inhibitors of HMGR (simvastatin), geranylgeranyltransferase (GGTI-298), farnesyltransferase (FTI-277), and/or caspase-1 (Z-VAD(Ome)-FMK). Following culture, cytokine production, caspase-1 activity, IL-1beta mRNA and Rac-1 activity were determined. RESULTS: Pharmacological inhibition of the mevalonate pathway specifically enhanced the release of IL-1alpha, IL-1beta and IL-18 and inhibited IL-1ra production by LPS-activated PBMCs and THP-1 cells. Simvastatin did not modify pro-IL-1beta expression, but enhanced caspase-1 activity, the enzyme responsible for IL-1beta and IL-18 maturation. GGTI-298 also enhanced IL-1-family cytokine production, showing that geranylgeranylation is involved in caspase-1 activation. Additionally, simvastatin enhanced Rac-1 activity. CONCLUSION: Pharmacological inhibition of the mevalonate pathway by statins highlighted the specific induction of the proinflammatory cytokines of the IL-1 family whose maturation is either directly (i.e. IL-1beta and IL-18), or indirectly (i.e. IL-1alpha) dependant on caspase-1.

l-Glutamine administration reduces oxidized glutathione and MAP kinase signaling in dystrophic muscle of mdx mice.

To determine whether glutamine (Gln) reduces the ratio of oxidized to total glutathione (GSSG/GSH) and extracellular signal-regulated kinase (ERK1/2) activation in dystrophic muscle. Four-week old mdx mice, an animal model for Duchenne muscular dystrophy and control (C57BL/10) received daily intraperitoneal injections of l-Gln (500 mg/kg/d) or 0.9% NaCl for 3 d. GSH and GSSG concentrations in gastrocnemius were measured using a standard enzymatic recycling procedure. Free amino acid concentrations in gastrocnemius were determined by ion exchange chromatography. Phosphorylated protein levels of ERK1/2 in quadriceps were examined using Western Blot. l-Gln decreased GSSG and GSSG/GSH (an indicator of oxidative stress). This was associated with decreased ERK1/2 phosphorylation. Muscle free Gln, glutamate (Glu), and the sum (Gln + Glu) were higher in mdx versus C57BL/10, at the basal level. Exogenous Gln decreased muscle free Glu and Gln + Glu in mdx only, whereas Gln was not affected. In conclusion, exogenous Gln reduces GSSG/GSH and ERK1/2 activation in dystrophic skeletal muscle of young mdx mice, which is associated with decreased muscle free Glu and Gln + Glu. This antioxidant protective mechanism provides a molecular basis for Gln's antiproteolytic effect in Duchenne muscular dystrophy children.

Role of interleukin-6 in cardiomyocyte/cardiac fibroblast interactions during myocyte hypertrophy and fibroblast proliferation.

The process of cardiac hypertrophy is considered to involve two components: that of cardiac myocyte (CM) enlargement and cardiac fibroblast (CF) proliferation. The interleukin-6 (IL-6) family cytokines have been implicated in a variety of cellular and molecular interactions between myocytes and non-myocytes (NCMs), which in turn have important roles in the development of cardiac hypertrophy. In the study of these interactions, we previously detected very high levels of IL-6 in supernatants of a "dedifferentiated model" of adult ventricular CMs cultured with CFs. In the present study, we have used this in vitro coculture system to examine how IL-6 is involved in the interactions between CMs and CFs during CM hypertrophy and CF proliferation. IL-6 and its signal transducer, 130-kDa glycoprotein (gp130), were detected by immunostaining cultured CMs and CFs with anti-IL-6 or anti-gp130 antibodies. Addition of anti-IL-6 or anti-gp130 antagonist antibodies into CM/CF cocultures induced a significant decrease in expression of atrial natriuretic peptide (ANP) and beta-myosin heavy chain (beta-MHC) in CMs. The presence of IL-6 antagonist also resulted in a decrease in the surface area of 12-day-old CMs cultured with CFs or in the presence of fibroblast conditioned medium (FCM), and decreased fibroblast proliferation in CM/CF cocultures, particularly in the presence of a gp130 antagonist. The results also show that angiotensin II (AngII) is mainly secreted by CFs and induces IL-6 secretion in CMs cultured with CFs or with FCM. In addition, the effects of IL-6 on cardiomyocyte hypertrophy and fibroblast proliferation were inhibited by addition of the AT-1 receptor antagonist, losartan. These results suggest that IL-6 contributes significantly to CM hypertrophy by an autocrine pathway and to fibroblast proliferation by a paracrine pathway and that these effects could be mediated by AngII.