1,721,177 research outputs found
Toll-like receptors (TLR) 4 and 2 regulate the innate immune response : Study of endotoxin influence in mice
Get PDFAbstractThe response of the innate immune system is triggered through Toll-like transmembrane receptors (TLR) that recognize a variety of microbial products. TLR4 is the principal mediator for Gram negative bacterial endotoxin (LPS), whereas TLR2 mediates the response to Gram positive bacteria, mycobacteria, and yeast. Stimulation of TLR activates complex cascades leading first to the production of inflammatory mediators, such as proinflammatory cytokines IL-1 α/β and TNF-α.Overproduction of inflammatory cytokines as well as failure in the activation of innate immunity are detrimental to the host. Excess inflammatory stimulation leads to a septic shock, which may cause multi-organ failure and even death. The lack of any innate response exposes the host to overwhelming bacterial infections. Appropriate regulation of the innate immune response could be a target for attempts to find therapeutics to septic shock. This experimental study focuses on functional activation of the signaling receptors TLR4 and TLR2 upon a LPS challenge.An acute inflammation model was used for both in vivo and in vitro experiments. LPS was used to stimulate a mouse macrophage cell line. It was administred intraperitoneally or intra-amniotically to non-pregnant or time-mated mice. The basal and induced mRNA expression levels and the protein production of TLRs as well as the mRNA expression of several inflammatory mediators were studied.The present study showed that the expression of TLR4 and TLR2 is strain and tissue-specific. At the mRNA level, the levels of TLR4 expression limited the extent of the acute cytokine response. The quality of the cytokine response was modulated by protein aggregates formed by TLR4 on the cell surface. The LPS challenge caused a marked increase in the expression of TLR2 mRNA but not the protein; the significance of this remains to be studied. The study further showed that the expression of TLRs is regulated during the perinatal period, and that the acute cytokine response to LPS in the lung develops during antenatal differentiation.The present study provides information about how the activation of TLR regulates the acute inflammatory response and further helps to elucidate new targets for the anti-inflammatory strategies in controlling inflammatory events.Tiivistelmä”Toll-like”-reseptorit (TLR) ovat solukalvon proteiineja, jotka spesifisesti tunnistavat erilaisia bakteerirakenteita. Infektiossa tällainen bakteerirakenne sitoutuu reseptoriin ja seurauksena solussa käynnistyy synnynnäinen immuunivaste eli tulehdusvälittäjäaineiden tuotto. Liiallinen tulehdusvälittäjäaineiden tuotto voi johtaa septiseen shokkiin eli verenmyrkytykseen, elinvaurioihin ja jopa kuolemaan. Septisen shokin synty voisi olla estettävissä immuunivasteen voimakkuuden tarkoituksenmukaisella säätelyllä. Väitöskirjassa on tutkittu, miten TLR4 ja TLR2 aktivoituvat bakteeri-infektiossa, tarkoituksena selvittää, säätelevätkö reseptorit immuunivasteen käynnistystä ja voimakkuutta solussa.Tutkimuksessa todettiin, että TLR4:n ja TLR2:n geenien ilmentymistä säädellään eri tavoin eri hiirikannoilla ja eri kudoksissa. TLR4-tason nousu aiheutti voimakkaamman immuunivasteen, kun taas reseptorin matala esiintymistaso laski immuunivasteen voimakkuutta. Lisäksi TLR4:aan solukalvolla sitoutuvat muut proteiinit vaikuttivat immuunivasteen laatuun. Tutkimuksessa todettiin myös, että TLR:n määrä sikiön keuhkoissa rajoittaa keuhkojen immuunivasteen kehittymistä.Tutkimus antaa tietoa siitä, miten TL-reseptorien aktivaatio säätelee synnynnäistä immuunipuolustusta ja selventää mahdollisuutta kontrolloida immuunivasteen voimakkuutta vaikuttamalla TL-reseptoriin.Academic Dissertation to be presented with the assent of the Faculty of Medicine, University of Oulu, for public discussion in the Auditorium 12 of Oulu University Hospital, on May 7th, 2004, at 12 noon.Abstract
The response of the innate immune system is triggered through Toll-like transmembrane receptors (TLR) that recognize a variety of microbial products. TLR4 is the principal mediator for Gram negative bacterial endotoxin (LPS), whereas TLR2 mediates the response to Gram positive bacteria, mycobacteria, and yeast. Stimulation of TLR activates complex cascades leading first to the production of inflammatory mediators, such as proinflammatory cytokines IL-1 α/β and TNF-α.
Overproduction of inflammatory cytokines as well as failure in the activation of innate immunity are detrimental to the host. Excess inflammatory stimulation leads to a septic shock, which may cause multi-organ failure and even death. The lack of any innate response exposes the host to overwhelming bacterial infections. Appropriate regulation of the innate immune response could be a target for attempts to find therapeutics to septic shock. This experimental study focuses on functional activation of the signaling receptors TLR4 and TLR2 upon a LPS challenge.
An acute inflammation model was used for both in vivo and in vitro experiments. LPS was used to stimulate a mouse macrophage cell line. It was administred intraperitoneally or intra-amniotically to non-pregnant or time-mated mice. The basal and induced mRNA expression levels and the protein production of TLRs as well as the mRNA expression of several inflammatory mediators were studied.
The present study showed that the expression of TLR4 and TLR2 is strain and tissue-specific. At the mRNA level, the levels of TLR4 expression limited the extent of the acute cytokine response. The quality of the cytokine response was modulated by protein aggregates formed by TLR4 on the cell surface. The LPS challenge caused a marked increase in the expression of TLR2 mRNA but not the protein; the significance of this remains to be studied. The study further showed that the expression of TLRs is regulated during the perinatal period, and that the acute cytokine response to LPS in the lung develops during antenatal differentiation.
The present study provides information about how the activation of TLR regulates the acute inflammatory response and further helps to elucidate new targets for the anti-inflammatory strategies in controlling inflammatory events.Tiivistelmä
”Toll-like”-reseptorit (TLR) ovat solukalvon proteiineja, jotka spesifisesti tunnistavat erilaisia bakteerirakenteita. Infektiossa tällainen bakteerirakenne sitoutuu reseptoriin ja seurauksena solussa käynnistyy synnynnäinen immuunivaste eli tulehdusvälittäjäaineiden tuotto. Liiallinen tulehdusvälittäjäaineiden tuotto voi johtaa septiseen shokkiin eli verenmyrkytykseen, elinvaurioihin ja jopa kuolemaan. Septisen shokin synty voisi olla estettävissä immuunivasteen voimakkuuden tarkoituksenmukaisella säätelyllä. Väitöskirjassa on tutkittu, miten TLR4 ja TLR2 aktivoituvat bakteeri-infektiossa, tarkoituksena selvittää, säätelevätkö reseptorit immuunivasteen käynnistystä ja voimakkuutta solussa.
Tutkimuksessa todettiin, että TLR4:n ja TLR2:n geenien ilmentymistä säädellään eri tavoin eri hiirikannoilla ja eri kudoksissa. TLR4-tason nousu aiheutti voimakkaamman immuunivasteen, kun taas reseptorin matala esiintymistaso laski immuunivasteen voimakkuutta. Lisäksi TLR4:aan solukalvolla sitoutuvat muut proteiinit vaikuttivat immuunivasteen laatuun. Tutkimuksessa todettiin myös, että TLR:n määrä sikiön keuhkoissa rajoittaa keuhkojen immuunivasteen kehittymistä.
Tutkimus antaa tietoa siitä, miten TL-reseptorien aktivaatio säätelee synnynnäistä immuunipuolustusta ja selventää mahdollisuutta kontrolloida immuunivasteen voimakkuutta vaikuttamalla TL-reseptoriin
Role of antibodies to glutamic acid decarboxylase in type 1 diabetes : Relation to other autoantibodies, HLA risk markers and clinical characteristics
Get PDFAbstractThe purpose of this research was to assess the role of antibodies to glutamic acid decarboxylase (GAD) in children with newly diagnosed type 1 diabetes in relation to other disease-associated autoantibodies and HLA-defined genetic disease susceptibility, to evaluate the role of GAD antibodies (GADA) in relation to clinical characteristics at the diagnosis of type 1 diabetes and to compare the frequency and levels of GADA between adult and childhood onset type 1 diabetes. The study population comprised altogether 999 children and adolescents with type 1 diabetes, 100 affected adult subjects and more than 370 non-diabetic controls. GADA were measured with a liquid radioligand assay, and a similar assay was used for the analysis of antibodies to the islet antigen 2 (IA-2) molecule. Islet cell antibodies (ICA) were determined with conventional immunofluorescence and insulin autoantibodies (IAA) with a liquid phase radioimmunoassay either in a tube or a plate format (microassay).GADA were detected at diagnosis in 68 to 73% of the children and adolescents with type 1 diabetes. GADA were more frequent in girls and in those older than 10 years of age at clinical disease manifestation. Subjects testing positive for GADA had higher levels of ICA and IAA than those negative for GADA. Multiple antibodies ( 2) were observed more often in girls and in children under the age of 5 years.Children with the HLA DR3/non-DR4 phenotype had the highest GADA levels, significantly higher than those seen in children with the DR4/non-DR3 combination. The highest prevalence of multiple autoantibodies was seen in subjects heterozygous for DR3/4. When studying HLA DQB1 genotypes those with the DQB1*02/y (y = other than *0302) genotype had the highest GADA levels as expected since DQB1*02 and DR3 are in strong linkage disease equilibrium. The same group had the lowest frequency of multiple antibodies among the children younger than 10 years of age. Patients diagnosed with type 1 diabetes before the age of 20 had a higher frequency of all four autoantibodies analysed than those presenting with clinical disease after the age of 20. The proportion of subjects testing negative for all four antibodies was substantially higher among adults than in those under the age of 20. The smallest age-related difference in antibody frequencies was observed for GADA, and the GADA-positive adult patients had on an average about three times higher antibody levels than the GADA-positive children.No association was observed between positivity for GADA and the degree of metabolic decompensation at the clinical presentation of type 1 diabetes. No significant differences were either seen between the subjects who tested positive for GADA at diagnosis and those who were negative in serum C-peptide concentrations, metabolic control or exogenous insulin requirement over the first 2 years of observation. The proportion of children in clinical remission was, however, lower among GADA-positive subjects than in GADA-negative patients at 18 months after the clinical manifestation. Positivity for multiple antibodies was associated with accelerated beta-cell destruction and increased exogenous insulin requirements over the 2-year observation period.The observations that GADA are related to female gender, older age and the HLA-DR3/ DQB1*02 haplotype suggest that a strong humoral immune response to GAD may reflect a propensity to general autoimmunity rather than specific beta-cell destruction.Academic Dissertation to be presented with the assent of the Faculty of Medicine, University of Oulu, for public discussion in Auditorium 8 of the University Hospital of Oulu, on June 6th, 2000, at 12 noon.Abstract
The purpose of this research was to assess the role of antibodies to glutamic acid decarboxylase (GAD) in children with newly diagnosed type 1 diabetes in relation to other disease-associated autoantibodies and HLA-defined genetic disease susceptibility, to evaluate the role of GAD antibodies (GADA) in relation to clinical characteristics at the diagnosis of type 1 diabetes and to compare the frequency and levels of GADA between adult and childhood onset type 1 diabetes. The study population comprised altogether 999 children and adolescents with type 1 diabetes, 100 affected adult subjects and more than 370 non-diabetic controls. GADA were measured with a liquid radioligand assay, and a similar assay was used for the analysis of antibodies to the islet antigen 2 (IA-2) molecule. Islet cell antibodies (ICA) were determined with conventional immunofluorescence and insulin autoantibodies (IAA) with a liquid phase radioimmunoassay either in a tube or a plate format (microassay).
GADA were detected at diagnosis in 68 to 73% of the children and adolescents with type 1 diabetes. GADA were more frequent in girls and in those older than 10 years of age at clinical disease manifestation. Subjects testing positive for GADA had higher levels of ICA and IAA than those negative for GADA. Multiple antibodies ( 2) were observed more often in girls and in children under the age of 5 years.
Children with the HLA DR3/non-DR4 phenotype had the highest GADA levels, significantly higher than those seen in children with the DR4/non-DR3 combination. The highest prevalence of multiple autoantibodies was seen in subjects heterozygous for DR3/4. When studying HLA DQB1 genotypes those with the DQB1*02/y (y = other than *0302) genotype had the highest GADA levels as expected since DQB1*02 and DR3 are in strong linkage disease equilibrium. The same group had the lowest frequency of multiple antibodies among the children younger than 10 years of age. Patients diagnosed with type 1 diabetes before the age of 20 had a higher frequency of all four autoantibodies analysed than those presenting with clinical disease after the age of 20. The proportion of subjects testing negative for all four antibodies was substantially higher among adults than in those under the age of 20. The smallest age-related difference in antibody frequencies was observed for GADA, and the GADA-positive adult patients had on an average about three times higher antibody levels than the GADA-positive children.
No association was observed between positivity for GADA and the degree of metabolic decompensation at the clinical presentation of type 1 diabetes. No significant differences were either seen between the subjects who tested positive for GADA at diagnosis and those who were negative in serum C-peptide concentrations, metabolic control or exogenous insulin requirement over the first 2 years of observation. The proportion of children in clinical remission was, however, lower among GADA-positive subjects than in GADA-negative patients at 18 months after the clinical manifestation. Positivity for multiple antibodies was associated with accelerated beta-cell destruction and increased exogenous insulin requirements over the 2-year observation period.
The observations that GADA are related to female gender, older age and the HLA-DR3/ DQB1*02 haplotype suggest that a strong humoral immune response to GAD may reflect a propensity to general autoimmunity rather than specific beta-cell destruction
Dynamics of IFN-β responses during respiratory viral infection: insights for therapeutic strategies
No full textRationale: Viral infections are major drivers of exacerbations and clinical burden in patients with asthma and chronic obstructive pulmonary disease (COPD). IFN-β is a key component of the innate immune response to viral infection. To date, studies of inhaled IFN-β treatment have not demonstrated a significant effect on asthma exacerbations.Objectives: The dynamics of exogenous IFN-β activity were investigated to inform on future clinical indications for this potential antiviral therapy.Methods: Monocyte-derived macrophages (MDMs), alveolar macrophages, and primary bronchial epithelial cells (PBECs) were isolated from healthy control subjects and patients with COPD and infected with influenza virus either prior to or after IFN-β stimulation. Infection levels were measured by the percentage of nucleoprotein 1-positive cells using flow cytometry. Viral RNA shedding and IFN-stimulated gene expression were measured by quantitative PCR. Production of inflammatory cytokines was measured using MSD.Measurements and Main Results: Adding IFN-β to MDMs, alveolar macrophages, and PBECs prior to, but not after, infection reduced the percentage of nucleoprotein 1-positive cells by 85, 56, and 66%, respectively (P < 0.05). Inhibition of infection lasted for 24 hours after removal of IFN-β and was maintained albeit reduced up to 1 week in MDMs and 72 hours in PBECs; this was similar between healthy control subjects and patients with COPD. IFN-β did not induce inflammatory cytokine production by MDMs or PBECs but reduced influenza-induced IL-1β production by PBECs.Conclusions: In vitro modeling of IFN-β dynamics highlights the potential for intermittent prophylactic doses of exogenous IFN-β to modulate viral infection. This provides important insights to aid the future design of clinical trials of IFN-β in asthma and COPD.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Cardiolipin-binding antibodies in patients with infections and autoimmune disorders
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