Combined Metabolomics and Transcriptomics Approaches to Assess the IL-6 Blockade as a Therapeutic of ALS: Deleterious Alteration of Lipid Metabolism

In amyotrophic lateral sclerosis (ALS), motor neuron degeneration occurs simultaneously with systemic metabolic impairment and neuroinflammation. Playing an important role in the regulation of both phenomena, interleukin (IL)-6, a major cytokine of the inflammatory response has been proposed as a target for management of ALS. Although a pilot clinical trial provided promising results in humans, another recent preclinical study showed that knocking out the IL-6 gene in mice carrying ALS did not improve clinical outcome. In this study, we aimed to determine the relevance of the IL-6 pathway blockade in a mouse model of ALS by using a pharmacological antagonist of IL-6, a murine surrogate of tocilizumab, namely MR16-1. We analyzed the immunological and metabolic effects of IL-6 blockade by cytokine measurement, blood cell immunophenotyping, targeted metabolomics, and transcriptomics. A deleterious clinical effect of MR16-1 was revealed, with a speeding up of weight loss (p = 0.0041) and decreasing body weight (p < 0.05). A significant increase in regulatory T-cell count (p = 0.0268) and a decrease in C-X-C ligand-1 concentrations in plasma (p = 0.0479) were observed. Metabolomic and transcriptomic analyses revealed that MR16-1 mainly affected branched-chain amino acid, lipid, arginine, and proline metabolism. IL-6 blockade negatively affected body weight, despite a moderated anti-inflammatory effect. Metabolic effects of IL-6 were mild compared with metabolic disturbances observed in ALS, but a modification of lipid metabolism by therapy was identified. These results indicate that IL-6 blockade did not improve clinical outcome of a mutant superoxide dismutase 1 mouse model of ALS.

Oncostatin M overexpression induces skin inflammation but is not required in the mouse model of imiquimod-induced psoriasis-like inflammation

Oncostatin M (OSM) has been reported to be overexpressed in psoriasis skin lesions and to exert proinflammatory effects in vitro on human keratinocytes. Here, we report the proinflammatory role of OSM in vivo in a mouse model of skin inflammation induced by intradermal injection of murine OSM-encoding adenovirus (AdOSM) and compare with that induced by IL-6 injection. Here, we show that OSM potently regulates the expression of genes involved in skin inflammation and epidermal differentiation in murine primary keratinocytes. In vivo, intradermal injection of AdOSM in mouse ears provoked robust skin inflammation with epidermal thickening and keratinocyte proliferation, while minimal effect was observed after AdIL-6 injection. OSM overexpression in the skin increased the expression of the S100A8/9 antimicrobial peptides, CXCL3, CCL2, CCL5, CCL20, and Th1/Th2 cytokines, in correlation with neutrophil and macrophage infiltration. In contrast, OSM downregulated the expression of epidermal differentiation genes, such as cytokeratin-10 or filaggrin. Collectively, these results support the proinflammatory role of OSM when it is overexpressed in the skin. However, OSM expression was not required in the murine model of psoriasis induced by topical application of imiquimod, as demonstrated by the inflammatory phenotype of OSM-deficient mice or wild-type mice treated with anti-OSM antibodies.

IMQ-induced skin inflammation in mice is dependent on IL-1R1 and MyD88 signaling but independent of the NLRP3 inflammasome

The pathogenesis of inflammatory skin diseases such as psoriasis involves the release of numerous proinflammatory cytokines, including members of the IL-1 family. Here we report overexpression of IL-1α, IL-1β, and IL-1 receptor antagonist mRNA, associated to expression of IL-23p19, IL-17A, and IL-22 in skin cells, upon topical application of the TLR7 agonist imiquimod (IMQ) in C57BL/6J mice. IMQ-induced skin inflammation was partially reduced in mice deficient for both IL-1α/IL-1β or for IL-1 receptor type 1 (IL-1R1), but not in IL-1α- or IL-1β-deficient mice, demonstrating the redundant activity of IL-1α and IL-1β for skin inflammation. NLRP3 or apoptosis-associated Speck-like protein containing a Caspase recruitment domain-deficient mice had no significant reduction of skin inflammation in response to IMQ treatment, mainly due to the redundancy of IL-1α. However, IMQ-induced skin inflammation was abolished in the absence of MyD88, the adaptor protein shared by IL-1R and TLR signaling pathways. These results are consistent with the TLR7 dependence of IMQ-induced skin inflammation. Thus, IL-1R1 contributes to the IMQ-induced skin inflammation, and disruption of MyD88 signaling completely abrogates this response.

IL22/IL-22R pathway induces cell survival in human glioblastoma cells

Interleukin-22 (IL-22) is a member of the IL-10 cytokine family that binds to a heterodimeric receptor consisting of IL-22 receptor 1 (IL-22R1) and IL-10R2. IL-22R expression was initially characterized on epithelial cells, and plays an essential role in a number of inflammatory diseases. Recently, a functional receptor was detected on cancer cells such as hepatocarcinoma and lung carcinoma, but its presence was not reported in glioblastoma (GBM). Two GBM cell lines and 10 primary cell lines established from patients undergoing surgery for malignant GBM were used to investigate the expression of IL-22 and IL-22R by using quantitative RT-PCR, western blotting and confocal microscopy studies. The role of IL-22 in proliferation and survival of GBM cell lines was investigated in vitro by BrdU and ELISA cell death assays. We report herein that the two subunits of the IL-22R complex are expressed on human GBM cells. Their activation, depending on exogenous IL-22, induced antiapoptotic effect and cell proliferation. IL-22 treatment of GBM cells resulted in increased levels of phosphorylated Akt, STAT3 signaling protein and its downstream antiapoptotic protein Bcl-xL and decreased level of phosphorylated ERK1/2. In addition, IL-22R subunits were expressed in all the 10 tested primary cell lines established from GBM tumors. Our results showed that IL-22R is expressed on GBM established and primary cell lines. Depending on STAT3, ERK1/2 and PI3K/Akt pathways, IL-22 induced GBM cell survival. These data are consistent with a potential role of IL-22R in tumorigenesis of GBM. Since endogenous IL-22 was not detected in all studied GBM cells, we hypothesize that IL-22R could be activated by immune microenvironmental IL-22 producing cells.

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-1β, 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.

Brief Report: Involvement of TNFRSF11A molecular defects in autoinflammatory disorders

OBJECTIVE

Autoinflammatory disorders are caused by a primary dysfunction of the innate immune system. Among these disorders are hereditary recurrent fevers, which are characterized by recurrent episodes of fever and inflammatory manifestations affecting multiple tissues. Hereditary recurrent fevers often lack objective diagnostic criteria, thereby hampering the identification of disease-causing genes. This study was undertaken to identify a gene responsible for hereditary recurrent fevers.

METHODS

Copy number variations and point mutations were sought by array-comparative genomic hybridization and polymerase chain reaction sequencing, respectively. Serum cytokine levels were measured using Luminex technology. The effect of TNFRSF11A molecular defects on NF-κB signaling in cells expressing wild-type and mutated forms of the receptor was evaluated by luciferase assay.

RESULTS

A patient with multiple congenital anomalies and hereditary recurrent fever was found to carry a de novo heterozygous complex chromosomal rearrangement encompassing a duplication of TNFRSF11A, a gene known to regulate fever in rodents. We also identified a heterozygous frameshift mutation (p.Met416Cysfs*110) in TNFRSF11A in a mother and daughter with isolated hereditary recurrent fever. This mutation was associated with increased secretion of several inflammatory cytokines (tumor necrosis factor α [TNFα], interleukin-18 [IL-18], IL-1 receptor antagonist, interferon-γ) and altered the biologic effects of the receptor on NF-κB signaling. The disease in the patients described herein exhibits striking clinical similarities to TNF receptor-associated periodic syndrome, another hereditary recurrent fever involving a gene of the same family (TNFRSF1A).

CONCLUSION

The involvement of TNFRSF11A in hereditary recurrent fever highlights the key role of this receptor in innate immunity. The present results also suggest that TNFRSF11A screening could serve as a new diagnostic test for autoinflammatory disorders.

Study of proliferation and 3D epidermal reconstruction from foreskin, auricular and trunk keratinocytes in children

OBJECTIVE

Severe burns in children are conventionally treated with split-thickness skin autografts or epidermal sheets. An alternative approach is to graft isolated keratinocytes. We evaluated foreskin and other anatomic sites as donor sources for autologous keratinocyte graft in children. We studied in vitro capacities of isolated keratinocytes to divide and reconstitute epidermal tissue.

METHODS

Keratinocytes were isolated from foreskin, auricular skin, chest and abdominal skin by enzymatic digestion. Living cell recovery, in vitro proliferation, epidermal reconstruction capacities and differentiation status were analyzed.

RESULTS

In vitro studies revealed the higher yield of living keratinocyte recovery from foreskin and higher potential in terms of proliferative capacity, regeneration and differentiation. Cultured keratinocytes from foreskin express lower amounts of differentiation markers than those isolated from trunk and ear. Histological analysis of reconstituted human epidermis derived from foreskin and inguinal keratinocytes showed a structured multilayered epithelium, whereas those obtained from ear pinna-derived keratinocytes were unstructured.

CONCLUSION

Our studies highlight the potential of foreskin tissue for autograft applications in boys. A suitable alternative donor site for autologous cell transplantation in female paediatric burn patients remains an open question in our department. We tested the hypothesis that in vitro studies and RHE reconstructive capacities of cells from different body sites can be helpful to select an optimal site for keratinocyte isolation before considering graft protocols for girls.

Inhibition of keratinocyte differentiation by the synergistic effect of IL-17A, IL-22, IL-1α, TNFα and oncostatin M

Keratinocyte differentiation program leading to an organized epidermis plays a key role in maintaining the first line of defense of the skin. Epidermal integrity is regulated by a tight communication between keratinocytes and leucocytes, particularly under cytokine control. Imbalance of the cytokine network leads to inflammatory diseases such as psoriasis. Our attempt to model skin inflammation showed that the combination of IL-17A, IL-22, IL-1α, OSM and TNFα (Mix M5) synergistically increases chemokine and antimicrobial-peptide expression, recapitulating some features of psoriasis. Other characteristics of psoriasis are acanthosis and down-regulation of keratinocyte differentiation markers. Our aim was to characterize the specific roles of these cytokines on keratinocyte differentiation, and to compare with psoriatic lesion features. All cytokines decrease keratinocyte differentiation markers, but IL-22 and OSM were the most powerful, and the M5 strongly synergized the effects. In addition, IL-22 and OSM induced epidermal hyperplasia in vitro and M5 induced epidermal thickening and decreased differentiation marker expression in a mouse model, as observed in human psoriatic skin lesions. This study highlights the precise role of cytokines in the skin inflammatory response. IL-22 and OSM more specifically drive epidermal hyperplasia and differentiation loss while IL-1α, IL-17A and TNFα were more involved in the activation of innate immunity.

IL-22 modulates IL-17A production and controls inflammation and tissue damage in experimental dengue infection

Dengue virus (DENV), a mosquito-borne flavivirus, is a public health problem in many tropical countries. IL-22 and IL-17A are key cytokines in several infectious and inflammatory diseases. We have assessed the contribution of IL-22 and IL-17A in the pathogenesis of experimental dengue infection using a mouse-adapted DENV serotype 2 strain (P23085) that causes a disease that resembles severe dengue in humans. We show that IL-22 and IL-17A are produced upon DENV-2 infection in immune-competent mice. Infected IL-22(-/-) mice had increased lethality, neutrophil accumulation and pro-inflammatory cytokines in tissues, notably IL-17A. Viral load was increased in spleen and liver of infected IL-22(-/-) mice. There was also more severe liver injury, as seen by increased transaminases levels and tissue histopathology. γδ T cells and NK cells are sources of IL-17A and IL-22, respectively, in liver and spleen. We also show that DENV-infected HepG2 cells treated with rhIL-22 had reduced cell death and decreased IL-6 production. IL-17RA(-/-) mice were protected upon infection and IL-17A-neutralizing-Ab-treatment partially reversed the phenotype observed in IL-22(-/-) -infected mice. We suggest that disrupting the balance between IL-22 and IL-17A levels may represent an important strategy to reduce inflammation and tissue injury associated with severe dengue infection.

Foreskin-isolated keratinocytes provide successful extemporaneous autologous paediatric skin grafts

Severe burns in children are conventionally treated with split-thickness skin autografts or epidermal sheets. However, neither early complete healing nor quality of epithelialization is satisfactory. An alternative approach is to graft isolated keratinocytes. We evaluated paediatric foreskin and auricular skin as donor sources, autologous keratinocyte transplantation, and compared the graft efficiency to the in vitro capacities of isolated keratinocytes to divide and reconstitute epidermal tissue. Keratinocytes were isolated from surgical samples by enzymatic digestion. Living cell recovery, in vitro proliferation and epidermal reconstruction capacities were evaluated. Differentiation status was analysed, using qRT-PCR and immunolabelling. Eleven children were grafted with foreskin-derived (boys) or auricular (girls) keratinocyte suspensions dripped onto deep severe burns. The aesthetic and functional quality of epithelialization was monitored in a standardized way. Foreskin keratinocyte graft in male children provides for the re-epithelialization of partial deep severe burns and accelerates wound healing, thus allowing successful wound closure, and improves the quality of scars. In accordance, in vitro studies have revealed a high yield of living keratinocyte recovery from foreskin and their potential in terms of regeneration and differentiation. We report a successful method for grafting paediatric males presenting large severe burns through direct spreading of autologous foreskin keratinocytes. This alternative method is easy to implement, improves the quality of skin and minimizes associated donor site morbidity. In vitro studies have highlighted the potential of foreskin tissue for graft applications and could help in tissue selection with the prospect of grafting burns for girls.

Involvement of IL-1 and oncostatin M in acanthosis associated with hypertensive leg ulcer

Hypertensive leg ulcer (HLU) is an inflammatory disease characterized by intense pain, alteration of vascularization, and skin necrosis. The optimal treatment relies on surgical removal of necrotic tissues covered by a split-skin graft. We studied the histomorphology of the lesions and investigated the involvement of inflammatory cells and cytokines to further define the physiopathology of HLU. We report epidermis acanthosis and a preferential occlusion of the precapillary arterioles with infiltration of neutrophils, macrophages, and T lymphocytes in the dermis. OSM, IL-1β, and IL-6 were overexpressed in the ulcer, whereas the Th17-derived cytokines were not. In vitro, the addition of IL-1β and OSM promoted acanthosis and destructuring of reconstructed epidermis. Exogenous IL-1β and OSM synergistically induced epidermal acanthosis in mice. These data show that OSM and IL-1β are not only a biological characteristic signature of HLU, but these cytokines reflect a specific inflammatory state, directly involved in the pathogenesis. We suggest that anti-cytokine biotherapies could be an alternative strategy to surgery to treat HLU.

Protective effect of IgM against colonization of the respiratory tract by nontypeable Haemophilus influenzae in patients with hypogammaglobulinemia

BACKGROUND

Primary immunoglobulin deficiencies lead to recurrent bacterial infections of the respiratory tract and bronchiectasis, even with adequate immunoglobulin replacement therapy. It is not known whether patients able to secrete IgM (eg, those with hyper-IgM [HIgM] syndrome) are as susceptible to these infections as patients who lack IgM production (eg, those with panhypogammaglobulinemia [PHG]).

OBJECTIVE

This study is aimed at identifying specific microbiological and clinical (infections) characteristics that distinguish immunoglobulin-substituted patients with PHG from patients with HIgM syndrome.

METHODS

A cohort of patients with HIgM syndrome (n = 25) and a cohort of patients with PHG (n = 86) were monitored prospectively for 2 years while receiving similar polyvalent immunoglobulin replacement therapies. Regular bacterial analyses of nasal swabs and sputum were performed, and clinical events were recorded. In parallel, serum and saliva IgM antibody concentrations were measured.

RESULTS

When compared with patients with PHG, patients with HIgM syndrome were found to have a significantly lower risk of nontypeable Haemophilus influenzae carriage in particular (relative risk, 0.39; 95% CI, 0.21-0.63). Moreover, patients with HIgM syndrome (including those unable to generate somatic hypermutations of immunoglobulin genes) displayed anti-nontypeable H influenzae IgM antibodies in their serum and saliva. Also, patients with HIgM syndrome had a lower incidence of acute respiratory tract infections.

CONCLUSIONS

IgM antibodies appear to be microbiologically and clinically protective and might thus attenuate the infectious consequences of a lack of production of other immunoglobulin isotypes in patients with HIgM syndrome. Polyvalent IgG replacement therapy might not fully compensate for IgM deficiency. It might thus be worth adapting long-term antimicrobial prophylactic regimens according to the underlying B-cell immunodeficiency phenotype.

Role of interleukin-1β 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-1β (IL-1β) signaling have been found in in vitro analyses. This prospective study was undertaken to assess the secretion of IL-1β and 3 IL-1β-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-1β 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-1β 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-1β secretion. Anakinra was discontinued after 14 months of therapy.

CONCLUSION

Our findings provide in vivo evidence of the crucial role of IL-1β 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.

Functional consequences of a germline mutation in the leucine-rich repeat domain of NLRP3 identified in an atypical autoinflammatory disorder

OBJECTIVE

To gain insight into the pathophysiology of an atypical familial form of an autoinflammatory disorder, characterized by autosomal-dominant sensorineural hearing loss, systemic inflammation, increased secretion of interleukin-1beta (IL-1beta), and the absence of any cutaneous manifestations, and to assess the functional consequences of a missense mutation identified in the leucine-rich repeat (LRR) domain of NLRP3.

METHODS

Microsatellite markers were used to test the familial segregation of the NLRP3 locus with the disease phenotype. All NLRP3 exons were screened for mutations by sequencing. Functional assays were performed in HEK 293T cells to determine the effects of mutated (versus normal) NLRP3 proteins on NF-kappaB activation, caspase 1 signaling, and speck formation.

RESULTS

A heterozygous NLRP3 missense mutation (p.Tyr859Cys) was identified in exon 6, which encodes the LRR domain of the protein. This mutation was found to segregate with the disease phenotype within the family, and had a moderate activating effect on speck formation and procaspase 1 processing and did not alter the inhibitory properties of NLRP3 on NF-kappaB signaling.

CONCLUSION

This report is the first to describe a familial form of a cryopyrinopathy associated with a mutation outside of exon 3 of NLRP3. This finding, together with the known efficacy of anti-IL-1 treatments in these disorders, underlines the importance of screening all exons of NLRP3 in patients who present with atypical manifestations. In addition, the gain of function associated with this mutation in terms of activation of caspase 1 signaling was consistent with the observed inflammatory phenotype. Therefore, this study of the functional consequences of an LRR mutation sheds new light on the clinical relevance of in vitro assays.

Cytokine-induced CEACAM1 expression on keratinocytes is characteristic for psoriatic skin and contributes to a prolonged lifespan of neutrophils

Carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1) is a cell-surface glycoprotein, belonging to the carcinoembryonic antigen family, expressed by human neutrophils, epithelial cells, activated T and NK cells. CEACAM1 is expressed as a cell-surface molecule with different isoforms or can be secreted as a soluble protein. Here, we show that keratinocytes in the outer epidermal layer of psoriatic skin express CEACAM1, unlike those in healthy skin or in cutaneous lesions of patients with atopic or nummular dermatitis. Stimulation of primary human keratinocytes or in vitro reconstituted epidermis with culture supernatants of activated psoriatic lesion-infiltrating T cells, IFN-gamma or oncostatin M, but not IL-17, induced the expression of transcripts for the CEACAM1-long and -short isoforms and cell-surface CEACAM1, whereas soluble CEACAM1 was not produced. The uppermost layers of the epidermis in psoriatic lesions also contain neutrophils, a cell type with inflammatory and antimicrobial properties. Coculture of CEACAM1-expressing keratinocytes or CHO transfectants with neutrophils delayed spontaneous apoptosis of the latter cells. These results show that cytokine-induced cell-surface expression of CEACAM1 by keratinocytes in the context of a psoriatic environment might contribute to the persistence of neutrophils and thus to ongoing inflammation and the decreased propensity for skin infection, typical for patients with psoriasis.

Development, cytokine profile and function of human interleukin 17-producing helper T cells

T(H)-17 cells are a distinct lineage of proinflammatory T helper cells that are essential for autoimmune disease. In mice, commitment to the T(H)-17 lineage is dependent on transforming growth factor-beta and interleukin 6 (IL-6). Here we demonstrate that IL-23 and IL-1beta induced the development of human T(H)-17 cells expressing IL-17A, IL-17F, IL-22, IL-26, interferon-gamma, the chemokine CCL20 and transcription factor RORgammat. In situ, T(H)-17 cells were identified by expression of the IL-23 receptor and the memory T cell marker CD45RO. Psoriatic skin lesions contained IL-23-producing dendritic cells and were enriched in the cytokines produced by human T(H)-17 cells that promote the production of antimicrobial peptides in human keratinocytes. Our data collectively indicate that human and mouse T(H)-17 cells require distinct factors during differentiation and that human T(H)-17 cells may regulate innate immunity in epithelial cells.

Oncostatin M Secreted by Skin Infiltrating T Lymphocytes Is a Potent Keratinocyte Activator Involved in Skin Inflammation

Cutaneous inflammatory diseases such as psoriasis vulgaris and atopic dermatitis are associated with altered keratinocyte function, as well as with a particular cytokine production profile of skin-infiltrating T lymphocytes. In this study we show that normal human epidermal keratinocytes express a functional type II oncostatin-M (OSM) receptor (OSMR) consisting of the gp130 and OSMRbeta components, but not the type I OSMR. The type II OSMR is expressed in skin lesions from both psoriatic patients and those with atopic dermatitis. Its ligand, OSM, induces via the recruitment of the STAT3 and MAP kinase pathways a gene expression profile in primary keratinocytes and in a reconstituted epidermis that is characteristic of proinflammatory and innate immune responses. Moreover, OSM is a potent stimulator of keratinocyte migration in vitro and increases the thickness of a reconstituted epidermis. OSM transcripts are enhanced in both psoriatic and atopic dermatitic skin as compared with healthy skin and mirror the enhanced production of OSM by T cells isolated from diseased lesions. Results from a microarray analysis comparing the gene-modulating effects of OSM with those of 33 different cytokines indicate that OSM is a potent keratinocyte activator similar to TNF-alpha, IL-1, IL-17, and IL-22 and that it acts in synergy with the latter cytokines in the induction of S100A7 and beta-defensin 2 expression, characteristic of psoriatic skin. Taken together, these results demonstrate that OSM and its receptor play an important role in cutaneous inflammatory responses in general and that the specific effects of OSM are associated with distinct inflammatory diseases depending on the cytokine environment.

ENDOTOXIN TOLERANCE ENHANCES INTERLEUKIN-10 RENAL EXPRESSION AND DECREASES ISCHEMIA-REPERFUSION RENAL INJURY IN RATS

The potential implication of interleukin (IL) 6, tumor necrosis factor alpha (TNF-alpha), and IL-10 in the protective effect of low-dose lipopolysaccharide (LPS) administration against renal ischemia-reperfusion injury was evaluated in a rat model. Eighteen male Sprague-Dawley rats were injected intravenously with either 0.5 mg/kg of LPS (tolerant group) or saline (control group) 2 days before surgery. Ischemic renal injury was induced by clamping the left renal artery for 60 min on rats immediately after right-side nephrectomy. Reperfusion was obtained by clamp removal and was studied at R0 (no reperfusion), 2H (R2), and 24H (R24) by renal tubular disorder characterization and by plasma creatinine as well as renal cytokine (IL-6, IL-10, and TNF-alpha) studies. No differences were observed between the two groups as concerns the period immediately after renal ischemia (R0). The endotoxin-tolerant group was associated with a significantly lower creatinine level at R24 (231 +/- 28 vs 315 +/- 36 micromol/L; P = 0.007). Pretreatment with LPS significantly reduced the degree of proximal tubule necrosis and outer medulla congestion. In such tolerant animals, renal IL-6 production was decreased, whereas IL-10 production was significantly increased at R2 and R24. There were no differences in TNF-alpha renal production. In this study, we demonstrated that administration of low doses of LPS to rats had a protective effect from renal reperfusion injury, and our data suggest that IL-10 might play a role in this phenomenon.

Keratinocytes as targets for interleukin-10-related cytokines: a putative role in the pathogenesis of psoriasis

Cytokines are key factors in the cross talk between the immune system and other systems including hepatic, nervous, cardiac and cutaneous systems, leading to an adaptive and integrated response of the organism to stress. They are also involved in the regulation of many processes, including hematopoiesis, the immune response and inflammation. IL-10 is one of the most important anti-inflammatory cytokines. Five cytokines structurally related to IL-10 have been described and presently form this family of cytokines: IL-19, IL-20, IL-22, IL-24 and IL-26. In contrast to IL-10, these cytokines display pro-inflammatory activities in different tissues, including skin. Indeed, some of them induce an inflammatory keratinocyte gene expression profile and an epidermis histology resembling psoriatic lesions. In this review, we discuss recent knowledge about the effects of cytokines of the IL-10 family on keratinocytes and their potential role in psoriasis, a cutaneous inflammatory disease.

IL-22 inhibits epidermal differentiation and induces proinflammatory gene expression and migration of human keratinocytes

IL-22 belongs to a family of cytokines structurally related to IL-10, including IL-19, IL-20, IL-24, and IL-26. In contrast to IL-10, IL-22 has proinflammatory activities. IL-22 signals through a class II cytokine receptor composed of an IL-22-binding chain, IL-22RA1, and the IL-10RB subunit, which is shared with the IL-10R. In the present study, we show that short-term cultured human epidermal keratinocytes express a functional IL-22R but no IL-10R. Accordingly, IL-22 but not IL-10 induces STAT3 activation in keratinocytes. Using a cDNA array screening approach, real-time RT-PCR, and Western blot analysis, we demonstrate that IL-22 up-regulates, in a dose-dependent manner, the expression of S100A7, S100A8, S100A9, a group of proinflammatory molecules belonging to the S100 family of calcium-binding proteins, as well as the matrix metalloproteinase 3, the platelet-derived growth factor A, and the CXCL5 chemokine. In addition, IL-22 induces keratinocyte migration in an in vitro injury model and down-regulates the expression of at least seven genes associated with keratinocyte differentiation. Finally, we show that IL-22 strongly induces hyperplasia of reconstituted human epidermis. Taken together, these results suggest that IL-22 plays an important role in skin inflammatory processes and wound healing.