Die Entzündungsreaktion der Arthrose wird als eine sekundäre Reaktion auf einen degenerativen Prozeß des Gelenkknorpels angesehen. Die Ursache für die Degeneration kann im Mißverhältnis zwischen Belastbarkeit und Beanspruchung liegen, es können metabolische Störungen (Urämie, Diabetes mellitus) verantwortlich gemacht werden, weswegen von sekundärer Arthrose gesprochen wird. Die Ursache der primären Arthrose bleibt unbekannt. Es kann als bewiesen angesehen werden der Zusammenhang mit Alter und Geschlecht der Patienten, denn Arthrose ist in der Regel eine Erkrankung jenseits des fünfzigsten Lebensjahres und betrifft vornehmlich Frauen. In der vorliegenden Arbeit wurde die Synovialis von 20 Patienten aufgearbeitet und hinsichtlich des enthaltenen entzündlichen Infiltrates untersucht. Unter Anwendung der indirekten Immunperoxidase Technik und der indirekten Immunfluoreszenz Technik wurde die Expression der Antigene CD 20, CD 23, CD 40, CD 27, IgG, IgA, IgM, Kappa, Lambda, CD 3, CD 4, CD 8, Ki M4, CD 68, Ki 67 sowie die Expression der Cytokine IL 2 und IL 10 analysiert. Die Synovialmembran zeigte histologisch eine Verbreiterung der Deckzellschicht, Knorpelfragmente innerhalb der Synovialmembran und ein insgesamt schwach ausgeprägtes entzündliches Infiltrat. In lediglich drei von 20 Fällen fand sich eine stärkere entzündliche Infiltration. Diese entzündlichen Infiltrate wiesen eine perivaskuläre Verteilung auf. Am häufigsten wurden in gefäßnahen Regionen B Lymphozyten identifiziert, Plasmazellen wiesen in der Regel einen deutlich größeren Abstand zum Gefäß auf. Unter den nachgewiesenen Plasmazellen fand sich eine prädominante Expression an IgG bei ausgewogener Anwesenheit sowohl der Kappa- als auch der Lambda- Leichtketten. T Lymphozyten waren ebenfalls zirkulär um die Gefäße anzutreffen und zeigten eine prädominante Interleukin 10 Expression. Lymphozytäre Aggregate, mit follikelähnlicher Struktur ließen sich in lediglich in 4 von 20 Fällen nachweisen. Makrophagen waren sowohl perivaskulär als auch in der Deckzellschicht nachweisbar. Ki M4 positive Retikulumzellen (FDC) waren dagegen nur in einem von 20 Fällen nachweisbar. Alle Zellpopulationen der Membrana synovialis wiesen nur eine schwache Proliferationsaktivität auf. Das Fehlen von dem Keimzentrum des Lymphfollikels vergleichbaren Strukturen, die deutliche Abwesenheit von Ki M4 positiver FDC's sowie die schwache Expression von Ki 67, sprechen trotz Anwesenheit der ebenfalls zur Antigenpräsentation befähigten Makrophagen gegen eine Einwanderung und Maturation nativer B Lymphozyten in die Membrana Synovialis. Wandern dagegen Gedächtniszellen in die Membrana synovialis ein, so ist eine Maturation mit Follikelbildung nicht mehr notwendig. Unter der Mithilfe von T Lymphozyten und Makrophagen können die B Lymphozyten zu Plasmazellen differenzieren. T Lymphozyten zeichnen sich ebenfalls durch eine starke perivaskuläre Verteilung aus. Dabei ist die Expression von IL 10 prädominant, was sich als eine Immunantwort von TH2-Typus interpretieren läßt. Diese ermöglicht eine Differenzierung der B Lymphozyten zu Plasmazellen. Reife B Lymphozyten, die unter dem Einfluß einer TH2 Subpopulation von CD 4 positiven T Lymphozyten ohne Keimzentrum zu Plasmazellen differenzieren, könnten ein Grund dafür sein, daß follikuläre Strukturen fehlen. Vorgereifte B Lymphozyten benötigen auch keine inflammatorisch hochpotenten Zytokine um eine schnelle Reifung und eine Immunantwort zu ermöglichen. Dies könnte ein Grund sein, warum die entzündliche Reaktion bei Arthrose so schwach ausgeprägt ist. / Inflammation in osteoarthritis is a secondary reaction to a degenerating process of the articular cartilage. Cause of Degeneration can be a disproportion of mechanical stress and resistance or metabolic diseases like diabetes mellitus. This kind of osteoarthritis is called "secondary osteoarthritis". Primary osteoarthritis has an unknown cause. Age and sex of the patient are a predictor for osteoarthritis, hense it is a disease of people above the age of 50 and more often it is found in women than in men. This paper investigated the synovial membranes of twenty patients to characterize the inflammatory Infiltrate. It characterized the cell surface antigen CD 20, CD 23, CD 40, CD 27, CD 3, CD 4, CD 8, Ki M4, CD 68, the antibodies IgG, IgA, IgM, Kappa, Lambda, the proliferating antigen Ki 67 and the expression profile of the cytokines IL 2 and IL 10 by using immunohistochemical staining (indirect immunoperoxidase technique and indirect immunofluorescence technique) with monoclonal antibodies. The synovial membrane shows in histology a dissemination of cover cells, fragments of cartilage and a slight expression of inflammatory infiltrate with a perivascular allocation. In only three of twenty cases we detected stronger inflammatory infiltrates. Most of the perivascular cells express CD 20. They are B lymphocytes. Plasma cells have more distance to the blood vessels and showed a predominant expression of IgG. T-lymphocytes were also detected perivascular. The expression of IL 10 was predominant. Lymphocytes aggregates like lymph follicle were detected in four of twenty cases. Macrophages were proved perivascular as well as in the cover cells. Ki M4 positive reticulum cells were found in only one of twenty cases. All kind of cells in the synovial membrane showed a low proliferation activity. The absence of germinal centers or comparable structures, the low expression of Ki M4 and Ki 67 speak against the immigration and maturation of native B lymphocytes in the synovial membrane. Memory B-lymphocytes don't need germinal centers or compatible structures for maturation, they can mature to plasma cells by help of T-lymphocytes, macrophages or other B-lymphocytes. It is more probably that the detected B lymphocytes are memory cells. The perivascular T lymphocytes in combination with the predominant expression of IL 10 may be interpreted as a TH2 immune reaction. This supports the maturation of B-lymphocytes to plasma cells. The maturation of memory B-lymphocytes under influence of TH2 immune reaction can be the reason for the missing of germinal centers or comparable structures. Matured B-lymphocytes don't need high-grade inflammatory cytokines for quick immune response. This is the possible reason for the low-grade inflammatory reaction of osteoarthritis.

Die rasanten Fortschritte in der neonatalen Intensivmedizin haben zwar die Ueberlebenschancen von Fruehgeborenen enorm verbessert, aber auch viele Probleme und Fragen aufgeworfen. In dieser Arbeit wurde untersucht, ob Hyperoxie Einfluss nimmt auf die Expression von apoptotischen Genen, Wachstumsfaktoren und Zytokinen und so ueber verschiedene Mechanismen und Signalwege zu einem Ungleichgewicht der ueber das neuronale Ueberleben entscheidenden Faktoren fuehrt. 6-Tage alte Ratten wurden fuer bestimme Zeitabschnitte (2, 6, 12, 24, 48, 72 Stunden) einer 80%igen Sauerstoffkonzentration ausgesetzt. In dieser Arbeit konnte am unreifen Rattengehirn nachgewiesen werden, dass eine 80%ige Sauerstoffkonzentration in der Atemluft maximal nach 12 bis 24 Stunden zu einer ausgepraegten, diffusen apoptotischen Neurodegeneration im Gehirn fuehrt. Die Exposition mit hoher Sauerstoffkonzentration fuehrte im unreifen Gehirn zu einer deutlich verminderten Expression der Neurotrophinen, wie deren Signalproteine ERK 1/2 und Akt. Als spezifischer Nachweis fuer eine apoptotische Neurodegeneration wurden neben dem histologischen Verfahren auf molekularer Ebene apoptotische Gene untersucht. Unter Hyperoxie kam es zu einer erhoehten Expression des Todesrezeptors Fas und einer gesteigerten Aktivitaet von Caspase-3.Des Weiteren fand sich infolge der Hyperoxieexposition ein drastischer Anstieg der inflammatorischen Zytokine IL-1beta und IL-18. Es zeigt sich also, dass hohe Sauerstoffkonzentrationen in einer sehr vulnerablen Phase der Hirnentwicklung (Phase des rapiden Hirnwachstums) zu massiven Veraenderungen fuehren, welche den bisher ungeklaerten diffusen Neuronenuntergang bei Fruehgeborenen erklaeren koennten. Die vorliegenden Ergebnisse implizieren aeu§erste Vorsicht bei der therapeutischen Anwendung von Sauerstoff bei Fruehgeborenen, fuer die die postnatalen Konditionen, verglichen mit den intrauterinen Bedingungen, immer hyperoxisch sind und die noch ueber ein unreifes Antioxidationssystem verfuegen. / Infants born prematurely may develop neurocognitive deficits without an obvious cause. Oxygen, which is widely used in neonatal medicine, constitutes one possible contributing neurotoxic factor, because it can trigger neuronal apoptosis in the developing brain of rodents. Premature infants are exposed to partial oxygen pressures that are fourfold higher compared to intrauterine conditions, even if no supplemental oxygen is administered. Here is reported that short exposures to nonphysiologic oxygen levels can trigger apoptotic neurodegeneration in the developing brain. Vulnerability to oxygen neurotoxicity is confined to the first 2 weeks of life, a period characterized by rapid growth, which in humans expands from the sixth month of pregnancy to the third year of life. Hyperoxia caused decreased expression of neurotrophins, and inactivation of survival signalling proteins extracellular signal-regulated kinase (ERK1/2), and protein kinase B (Akt). In addition we hypothesized that two caspase-1-processed cytokines, interleukin (IL)-1beta and IL-18, are involved in oxygen-induced neuronal cell death. Six-day-old Wistar rats were exposed to 80% oxygen for various time periods (2, 6, 12, 24, 48, 72 hours). Neuronal cell death in the brain, as assessed by silver staining, peaked at 12 to 24 hours and was preceded by a marked increase in mRNA of IL-1beta, IL-18 and FAS and a decrease in mRNA and protein levels of neurotrophins and ERK1/2 and Akt Our findings reveal mechanisms that could potentially damage the developing brain of human premature neonates.

INTRODUÇÃO: Apesar do contínuo progresso no tratamento e suporte clínico a sepse continua sendo uma das principais causas de morbidade e mortalidade nas unidades de terapia intensiva, com desfechos semelhantes ao longo dos últimos 50 anos. A suscetibilidade à infecção grave no recém-nascido é parcialmente devida à imaturidade do sistema imune inato associado à mínima em exposição antigênica in utero e à ação ineficaz das células T efetoras e das célula B. Embora a ativação do sistema imune inato por padrões de reconhecimento (PRR) como os dos receptores Toll-like (TLR) tenham sua importância amplamente reconhecida nos últimos anos, seu comportamento frente a uma infecção in vivo ainda não foi completamente compreendido. Neste trabalho nós analisamos a expressão dos TLR-2 e TLR-4 em células apresentadoras de antígeno em recém-nascidos com e sem sepse. CAUSUÍSTICA E MÉTODO: Trata-se de um estudo prospectivo realizado no período entre fevereiro de 2011 e janeiro de 2013 onde foram incluídos quarenta e cinco recém-nascidos a termo, sem malformação congênita, admitidos na Unidade de Cuidados Intensivos Neonatal do Instituto da Criança-HCFMUSP e divididos em grupos 1 e 2. O grupo 1 consistiu em 27 recém-nascidos com diagnóstico clínico e laboratorial de sepse tardia enquanto que o grupo 2 foi composto por 18 recém-nascidos sem quadro séptico vigente. As citocinas foram determinadas por teste de CBA em sangue periférico. A expressão e MFI dos TLR-2 e TLR-4 foi determinado por imunofenotipagem em APCs e linfócitos no sangue periférico total através de análise pelo citômetro de fluxo BD FACSDiva. RESULTADOS: Os dados clínicos foram semelhantes entre os grupos 1 e 2, exceto para o estado infeccioso. Microrganismos foram identificados em 37 % no grupo 1 e estes tiveram níveis mais elevados de citocinas pró-inflamatórias (IL-8, IL-6, IL-1beta) e de citocina anti-inflamatória (IL-10). Nas células dendríticas, a expressão de TLR-2 e 4 foi semelhante entre os grupos enquanto que houve menor expressão nos pacientes infectados da molécula co-estimuladora CD86 (p < 0,05) e expressão semelhante de CD1a e CD80 em relação aos RN não infectados. No monócito, o MFI para TLR-2 e a freqüência de expressão do TLR-4 foi maior no grupo 1 (p = 0,01). Apesar da frequência de linfócitos totais ter sido mais baixa no grupo 1 (p = 0,002), não foi observada diferença quanto as suas subpopulações exceto em relação a maior frequência de LT efetor no grupo infectado com menor expressão da molécula CD28. Houve maior frequência de LB ativados no grupo 1 enquanto que a população total e as demais subpopulações foram semelhantes em número, moléculas de ativação e na expressão dos TLR-2 e 4 em ambos os grupos. CONCLUSÃO: Este estudo analisou a resposta imune inata no recém-nascido com e sem sepse. As IL-6, IL-8 e IL-10 foram bons indicadores desta doença. Recém-nascidos sépticos, que dependem quase exclusivamente do sistema imune inato, apresentaram pouca resposta in vivo na ativação de células dendríticas e monócitos propiciando uma resposta imune deficiente e maior susceptibilidade à infecção / INTRODUCTION: Despite continuous progress in the clinical treatment and other supportive care therapies, sepsis remains a leading cause of morbidity and mortality in the intensive care unit with similar outcome throughout the past 50 years. The susceptibility to severe infection is partially due to newborn immature innate immune system associated to minimal in utero antigen exposure and effector T and B cell impaired function. Although the importance of pattern recognition domains such as Toll-like receptors (TLR) in the innate immune system activation has been fully acknowledged within the last few years its behavior in front of an in vivo infection scenario is still not completely understood. Here we analyzed the TLR-2 and TLR-4 expression in antigen-presenting cell in healthy and septic newborns. PATIENTS AND METHODS: This prospective study was conducted during the period from February 2011 until January 2013 at Sao Paulo University, Sao Paulo, Brazil. Forty-five term newborns without congenital malformation were included from the Newborn Intensive Care Unit at Children\'s Hospital. As group 1, 27 newborns who had clinical and laboratory diagnostic of late onset sepsis were included while 18 newborns were evaluated in a non-septic status and were included at group 2. Cytokines were measured by cytometric bead array in peripheral blood. TLR-2 and TLR-4 expression and MFI were determined by immunophenotyping at peripheral whole blood in APC cells and lymphocytes and analyzed on a BD FACSDiva flow cytometer. RESULTS: Clinical data was similar between septic and non-septic groups except for the infectious status. Group 1 had microorganisms identified in 37 % septic newborns associated with higher levels of pro-inflammatory (IL-8, IL-6, IL-1beta) and anti-inflammatory interleukins (IL-10). When it comes to dendritic cells, the expression of TLR-2 and 4 was similar between groups whereas there was lower expression of co-molecule CD86 (p < 0,05) and similar expression of CD1a and CD80 between infected and non-infected patients. At monocytes, the MFI for TLR-2 and the frequency of TLR-4 expression was higher in infected newborn (p=0,01). There were lower levels of total lymphocytes in infected patients (p=0,002) but no difference was observed in T cells subtypes frequency except for higher levels of effector T cell in infected group with lower expression of CD28 molecule. Group 1 had higher levels of activated B cell whereas total population and the other subsets were similar in number, activation molecules and TLR-2 and 4 expressions in both groups. CONCLUSION: This study investigated the innate immune response in septic and non-septic newborn. Interleukin levels 6, 8 and 10 were good indicators of sepsis. Septic newborns, which count most exclusively with innate immune system, had little in vivo response at dendritic cell and monocyte activation leading to an impaired immune response and increased susceptibility to infection

INTRODUÇÃO: Apesar do contínuo progresso no tratamento e suporte clínico a sepse continua sendo uma das principais causas de morbidade e mortalidade nas unidades de terapia intensiva, com desfechos semelhantes ao longo dos últimos 50 anos. A suscetibilidade à infecção grave no recém-nascido é parcialmente devida à imaturidade do sistema imune inato associado à mínima em exposição antigênica in utero e à ação ineficaz das células T efetoras e das célula B. Embora a ativação do sistema imune inato por padrões de reconhecimento (PRR) como os dos receptores Toll-like (TLR) tenham sua importância amplamente reconhecida nos últimos anos, seu comportamento frente a uma infecção in vivo ainda não foi completamente compreendido. Neste trabalho nós analisamos a expressão dos TLR-2 e TLR-4 em células apresentadoras de antígeno em recém-nascidos com e sem sepse. CAUSUÍSTICA E MÉTODO: Trata-se de um estudo prospectivo realizado no período entre fevereiro de 2011 e janeiro de 2013 onde foram incluídos quarenta e cinco recém-nascidos a termo, sem malformação congênita, admitidos na Unidade de Cuidados Intensivos Neonatal do Instituto da Criança-HCFMUSP e divididos em grupos 1 e 2. O grupo 1 consistiu em 27 recém-nascidos com diagnóstico clínico e laboratorial de sepse tardia enquanto que o grupo 2 foi composto por 18 recém-nascidos sem quadro séptico vigente. As citocinas foram determinadas por teste de CBA em sangue periférico. A expressão e MFI dos TLR-2 e TLR-4 foi determinado por imunofenotipagem em APCs e linfócitos no sangue periférico total através de análise pelo citômetro de fluxo BD FACSDiva. RESULTADOS: Os dados clínicos foram semelhantes entre os grupos 1 e 2, exceto para o estado infeccioso. Microrganismos foram identificados em 37 % no grupo 1 e estes tiveram níveis mais elevados de citocinas pró-inflamatórias (IL-8, IL-6, IL-1beta) e de citocina anti-inflamatória (IL-10). Nas células dendríticas, a expressão de TLR-2 e 4 foi semelhante entre os grupos enquanto que houve menor expressão nos pacientes infectados da molécula co-estimuladora CD86 (p < 0,05) e expressão semelhante de CD1a e CD80 em relação aos RN não infectados. No monócito, o MFI para TLR-2 e a freqüência de expressão do TLR-4 foi maior no grupo 1 (p = 0,01). Apesar da frequência de linfócitos totais ter sido mais baixa no grupo 1 (p = 0,002), não foi observada diferença quanto as suas subpopulações exceto em relação a maior frequência de LT efetor no grupo infectado com menor expressão da molécula CD28. Houve maior frequência de LB ativados no grupo 1 enquanto que a população total e as demais subpopulações foram semelhantes em número, moléculas de ativação e na expressão dos TLR-2 e 4 em ambos os grupos. CONCLUSÃO: Este estudo analisou a resposta imune inata no recém-nascido com e sem sepse. As IL-6, IL-8 e IL-10 foram bons indicadores desta doença. Recém-nascidos sépticos, que dependem quase exclusivamente do sistema imune inato, apresentaram pouca resposta in vivo na ativação de células dendríticas e monócitos propiciando uma resposta imune deficiente e maior susceptibilidade à infecção / INTRODUCTION: Despite continuous progress in the clinical treatment and other supportive care therapies, sepsis remains a leading cause of morbidity and mortality in the intensive care unit with similar outcome throughout the past 50 years. The susceptibility to severe infection is partially due to newborn immature innate immune system associated to minimal in utero antigen exposure and effector T and B cell impaired function. Although the importance of pattern recognition domains such as Toll-like receptors (TLR) in the innate immune system activation has been fully acknowledged within the last few years its behavior in front of an in vivo infection scenario is still not completely understood. Here we analyzed the TLR-2 and TLR-4 expression in antigen-presenting cell in healthy and septic newborns. PATIENTS AND METHODS: This prospective study was conducted during the period from February 2011 until January 2013 at Sao Paulo University, Sao Paulo, Brazil. Forty-five term newborns without congenital malformation were included from the Newborn Intensive Care Unit at Children\'s Hospital. As group 1, 27 newborns who had clinical and laboratory diagnostic of late onset sepsis were included while 18 newborns were evaluated in a non-septic status and were included at group 2. Cytokines were measured by cytometric bead array in peripheral blood. TLR-2 and TLR-4 expression and MFI were determined by immunophenotyping at peripheral whole blood in APC cells and lymphocytes and analyzed on a BD FACSDiva flow cytometer. RESULTS: Clinical data was similar between septic and non-septic groups except for the infectious status. Group 1 had microorganisms identified in 37 % septic newborns associated with higher levels of pro-inflammatory (IL-8, IL-6, IL-1beta) and anti-inflammatory interleukins (IL-10). When it comes to dendritic cells, the expression of TLR-2 and 4 was similar between groups whereas there was lower expression of co-molecule CD86 (p < 0,05) and similar expression of CD1a and CD80 between infected and non-infected patients. At monocytes, the MFI for TLR-2 and the frequency of TLR-4 expression was higher in infected newborn (p=0,01). There were lower levels of total lymphocytes in infected patients (p=0,002) but no difference was observed in T cells subtypes frequency except for higher levels of effector T cell in infected group with lower expression of CD28 molecule. Group 1 had higher levels of activated B cell whereas total population and the other subsets were similar in number, activation molecules and TLR-2 and 4 expressions in both groups. CONCLUSION: This study investigated the innate immune response in septic and non-septic newborn. Interleukin levels 6, 8 and 10 were good indicators of sepsis. Septic newborns, which count most exclusively with innate immune system, had little in vivo response at dendritic cell and monocyte activation leading to an impaired immune response and increased susceptibility to infection

Indiana University-Purdue University Indianapolis (IUPUI) / Neurofibromatosis Type 1 (NF1) is a genetic disorder resulting from mutations in the NF1 tumor suppressor gene. Neurofibromin is the protein product of NF1 and functions as a negative regulator of Ras activity in both hematopoietic and vascular wall cells, which are critical for maintaining blood vessel homeostasis. NF1 patients are predisposed to chronic inflammation and premature cardiovascular disease, including development of large arterial aneurysms, which may result in sudden death secondary to their rupture. However, the molecular pathogenesis of NF1 aneurysm formation is completely unknown. Utilizing a novel model of Nf1 murine aneurysm formation, we demonstrate that heterozygous inactivation of Nf1 (Nf1+/-) results in enhanced aneurysm formation with myeloid cell infiltration and increased reactive oxygen species in the vessel wall. Using cell lineage-restricted transgenic mice, we show that loss of a single Nf1 allele in myeloid cells is sufficient to recapitulate the Nf1+/- aneurysm phenotype in vivo. Additionally, oral administration of simvastatin, a statin with antioxidant and anti-inflammatory effects, significantly reduced aneurysm formation in Nf1+/- mice. Finally, the antioxidant apocynin was administered orally and also resulted in a significant reduction of Nf1+/- aneurysms. These data provide genetic and pharmacologic evidence that neurofibromin-deficient myeloid cells are the central cellular triggers for aneurysm formation in a novel model of NF1 vascular disease, implicated oxidative stress as the key biochemical mechanisms of NF1 aneurysm formation and provide a potential therapeutic target for NF1 vasculopathy.

Indiana University-Purdue University Indianapolis (IUPUI) / IL-17-producing T cells are critical to the development of pathogen and tumor immunity, but also contribute to the pathology of autoimmune diseases and allergic inflammation. CD8+ (Tc17) and CD4+ (Th17) IL-17-secreting T cells develop in response to a cytokine environment that activates Signal Transducer and Activator of Transcription (STAT) proteins, though the mechanisms underlying Tc17/Th17 development and stability are still unclear. In vivo, Tc17 cells clear vaccinia virus infection and acquire cytotoxic potential, that is independent of IL-17 production and the acquisition of IFN-γ-secreting potential, but partially dependent on Fas ligand, suggesting that Tc17-mediated vaccinia virus clearance is through cell killing independent of an acquired Tc1 phenotype. In contrast, memory Th cells and NKT cells display STAT4-dependent IL-23-induced IL-17 production that correlates with Il23r expression. IL-23 does not activate STAT4 nor do other STAT4-activating cytokines induce Il23r expression in these populations, suggesting a T cell-extrinsic role for STAT4 in mediating IL-23 responsiveness. Although IL-23 is important for the maintenance of IL-17-secreting T cells, it also promotes their instability, often resulting in a pathogenic Th1-like phenotype in vitro and in vivo. In vitro-derived Th17 cells are also flexible when cultured under polarizing conditions that promote Th2 or Th9 differentiation, adopting the respective effector programs, and decreasing IL-17 production. However, in models of allergic airway disease, Th17 cells do not secrete alternative cytokines nor adopt other effector programs, and remain stable IL-17-secretors. In contrast to Th1-biased pro-inflammatory environments that induce Th17 instability in vivo, during allergic inflammatory disease, Th17 cells are comparatively stable, and retain the potential to produce IL-17. Together these data document that the inflammatory environment has distinct effects on the stability of IL-17-secreting T cells in vivo.