Eggerthella lenta augments preclinical autoantibody production and metabolic shift mimicking senescence in arthritis

Although the etiology of rheumatoid arthritis (RA) is unknown, a strong genetic predisposition and the presence of preclinical antibodies before the onset of symptoms is documented. An expansion of Eggerthella lenta is associated with severe disease in RA. Here, using a humanized mouse model of collagen-induced arthritis, we determined the impact of E. lenta abundance on RA severity. Naïve mice gavaged with E. lenta produce preclinical rheumatoid factor and, when induced for arthritis, develop severe disease. The augmented antibody response was much higher in female mice, and among patients with RA, women had higher average load of E. lenta. Expansion of E. lenta increased CXCL5 and CD4 T cells, and both interleukin-17- and interferon-γ-producing B cells. Further, E. lenta gavage caused gut dysbiosis and decline in amino acids and nicotinamide adenine dinucleotide with an increase in microbe-dependent bile acids and succinyl carnitine causing systemic senescent-like inflammation.

Administration of Human Derived Upper gut Commensal Prevotella histicola delays the onset of type 1 diabetes in NOD mice

BACKGROUND

Type 1 diabetes (T1D) is an autoimmune disease that is increasing in prevalence worldwide. One of the contributing factors to the pathogenesis of T1D is the composition of the intestinal microbiota, as has been demonstrated. in T1D patients, with some studies demonstrating a deficiency in their levels of Prevotella. We have isolated a strain of Prevotella histicola from a duodenal biopsy that has anti-inflammatory properties, and in addition, alters the development of autoimmune diseases in mouse models. Therefore, our hypothesis is that the oral administration of P. histicola might delay the development of T1D in the non-obese diabetic (NOD) mice. To assess this, we used the following materials and methods. Female NOD mice (ages 5-8 weeks) were administered every other day P. histicola that was cultured in-house. Blood glucose levels were measured every other week. Mice were sacrificed at various time points for histopathological analysis of the pancreas. Modulation of immune response by the commensal was tested by analyzing regulatory T-cells and NKp46+ cells using flow cytometry and intestinal cytokine mRNA transcript levels using quantitative RT-PCR. For microbial composition, 16 s rRNA gene analysis was conducted on stool samples collected at various time points.

RESULTS

Administration of P. histicola in NOD mice delayed the onset of T1D. Beta diversity in the fecal microbiomes demonstrated that the microbial composition of the mice administered P. histicola was different from those that were not treated. Treatment with P. histicola led to a significant increase in regulatory T cells with a concomitant decrease in NKp46+ cells in the pancreatic lymph nodes as compared to the untreated group after 5 weeks of treatment.

CONCLUSIONS

These observations suggest that P. histicola treatment delayed onset of diabetes by increasing the levels of regulatory T cells in the pancreatic lymph nodes. This preliminary work supports the rationale that enteral exposure to a non pathogenic commensal P. histicola be tested as a future therapy for T1D.

A novel humanized model of rheumatoid arthritis associated lung disease

Cigarette smoking has been implicated in the pathogenesis of seropositive rheumatoid arthritis (RA), as well as RA-associated lung disease. Fibrotic interstitial lung disease as well as emphysema occur in RA and cause substantial morbidity. We used arthritis-susceptible HLA-DQ8 transgenic mice to generate RA-associated lung disease. Mice were exposed to cigarette smoke (CS) prior to induction of arthritis, and subsequently injected with a low dose of bleomycin intra-tracheally to induce lung injury. Exposure of arthritic mice to both CS and bleomycin led to a significant reduction in lung compliance consistent with development of diffuse lung disease. Morphologic evaluation of the lung demonstrated areas of emphysematous change and co-existent fibrosis, consistent with a combined pattern of fibrosis and emphysema. These changes were accompanied by inflammatory cell infiltration and upregulation of fibrosis-associated genes. This humanized mouse model can serve as a valuable research tool to understand the pathogenesis of RA associated lung disease.

Prevotella histicola Protects From Arthritis by Expansion of Allobaculum and Augmenting Butyrate Production in Humanized Mice

Bacterial therapeutics are the emergent alternatives in treating autoimmune diseases such as Rheumatoid Arthritis [RA]. P. histicola MCI 001 is one such therapeutic bacterium that has been proven to treat autoimmune diseases such as RA and multiple sclerosis [MS] in animal models. The present study characterized P. histicola MCI 001 isolated from a human duodenal biopsy, and evaluated its impact on the gut microbial and metabolic profile in a longitudinal study using the collagen-induced arthritis model in HLA-DQ8.AEo transgenic mice. P. histicola MCI 001 though closely related to the type strain of P. histicola, DSM 19854, differed in utilizing glycerol. In culture, P. histicola MCI 001 produced vitamins such as biotin and folate, and was involved in digesting complex carbohydrates and production of acetate. Colonization study showed that duodenum was the predominant niche for the gavaged MCI 001. A longitudinal follow-up of gut microbial profile in arthritic mice treated with MCI 001 suggested that dysbiosis caused due to arthritis was partially restored to the profile of naïve mice after treatment. A taxon-level analysis suggested an expansion of intestinal genus Allobaculum in MCI001 treated arthritic mice. Eubiosis achieved post treatment with P. histicola MCI 001 was also reflected in the increased production of short-chain fatty acids [SCFAs]. Present study suggests that the treatment with P. histicola MCI 001 leads to an expansion of Allobaculum by increasing the availability of simple carbohydrates and acetate. Restoration of microbial profile and metabolites like butyrate induce immune and gut homeostasis.

Prevotella histicola treatment reduces arthritic pain and partially normalizes gut microbiota and metabolites

We have previously shown that treatment with a novel human commensal, Prevotella histicola, isolated from a duodenal biopsy, can protect HLA-DQ8 mice from collagen induced arthritis (CIA), a model for RA, by modulating the systemic immune response. The present study analyzed the functional and mechanistic impact of P. histicola by comparing pain, motor function, gut microbiota and metabolites in treated and non-treated arthritic DQ8 mice. P. histicola treatment reduced the arthritis-associated pain by improving the motor function when compared to control mice. Analysis of synovium showed that P. histicola treatment increased T regulatory cells and reduced the levels of IL6 in the synovium of arthritic mice which were associated with reduced pain. Treated mice showed P. histicola colonization in the duodenum, a niche from where it was isolated. Further, P. histicola treatment showed varied effects based on circadian rhythm. A longitudinal follow-up of the gut microbial profile in different gut sections suggested that dysbiosis caused due to arthritis in DQ8 is partly normalized to naïve profile after treatment with P. histicola. Treated mice showed an expansion of genus Allobaculum, a butyrate-producing Firmicutes in the guts of DQ8 arthritic mice as compared to pre-treatment. The post-treatment restoration was also reflected in short-chain fatty acids and glucose assimilation rates in T cells. The present study proposes that P. histicola treatment of arthritis in DQ8 mice leads to gut homeostasis. Normalized microbial diversity and metabolites lead to immune regulation resulting in reduced inflammation with improved physical function. The observations suggest P. histicola as a strong candidate for monoclonal bio-therapeutics.

Autoimmunity-Associated Gut Commensals Modulate Gut Permeability and Immunity in Humanized Mice

OBJECTIVE

Although the etiology of rheumatoid arthritis (RA) is unknown, recent studies have led to the concept that gut dysbiosis may be involved in onset. In this study, we aimed to determine if human gut commensals modulate the immune response and gut epithelial integrity in DQ8 mice.

METHODS

DQ8 mice were orally gavaged with RA-associated (Eggerthella lenta or Collinsella aerofaciens) and non-associated (Prevotella histicola or Bifidobacterium sp.) on alternate days for 1 week in naïve mice. Some mice were immunized with type II collagen and oral gavage continued for 6 weeks and followed for arthritis. Epithelial integrity was done by FITC-Dextran assay. In addition, cytokines were measured in sera by ELISA and various immune cells were quantified using flow cytometry.

RESULTS

Gut permeability was increased by the RA-associated bacteria and was sex and age-dependent. In vivo and in vitro observations showed that the RA-non-associated bacteria outgrow the RA-associated bacteria when gavaged or cultured together. Mice gavaged with the RA-non-associated bacteria produced lower levels of pro-inflammatory MCP-1 and MCP-3 and had lower numbers of Inflammatory monocytes CD11c+Ly6c+, when compared to controls. E. lenta treated naïve mice produce Th17 cytokines.

CONCLUSIONS

Our studies suggest that gut commensals influence immune response in and away from the gut by changing the gut permeability and immunity. Dysbiosis helps the growth of RA-associated bacteria and reduces the beneficial bacteria.

Development of a real-time PCR method for quantification of Prevotella histicola from the gut

We designed species-specific primers and developed a qPCR method for enumerating P. histicola from intestinal samples. The two designed primer sets showed specificity for the target 16S rRNA gene of P. histicola. The absolute qPCR method was sensitive to quantify as few as 10³ colony-forming units (CFU) in the gut.

Human gut-derived commensal Prevotella histicola suppress experimental autoimmune encephalomyelitis in humanized mice

Our recent multiple sclerosis (MS) microbiome study indicates an important role of gut microbiota in pathogenesis of MS, an autoimmune disease of central nervous system. Gut microbiota help in maintaining immune-homeostasis by regulating balance between CD4+CD25+FoxP3+ regulatory T cells (Tregs) and pro-inflammatory Th1/Th17 cells. A shift of balance towards Th1/Th17 cells leading to inflammation and demyelination in central nervous system (CNS), is suggested to be responsible of disease initiation and/or relapses in MS. Therefore, gut commensals capable of restoring the microbiome to a healthy state could provide novel therapeutic options for treating autoimmune diseases including MS. Here, we report identification of human gut-derived commensal bacteria, Prevotella histicola (P. histicola), which can suppress an autoimmune disease in HLA class-II transgenic model of experimental autoimmune encephalomyelitis (EAE), an experimental model of MS. P. histicola suppresses disease through modulation of systemic immune response. P. histicola challenge led to a decrease in pro-inflammatory Th1 (IFNγ) and Th17 (IL17) cytokines, and increase in the frequencies of CD4+FoxP3+ Tregs, tolerogenic dendritic cells and suppressive macrophages. We also observed that mice with EAE had a altered gut microbiota compared to naïve mice and treatment with P. histicola restored gut flora to a normal state which further support an important role of gut microbiota in EAE/MS. Our study provides compelling evidence that administration of gut commensals may regulate a systemic immune response and have a possible role in the treatment of autoimmune diseases.

Cigarette Smoke Induces Immune Responses to Vimentin in both, Arthritis-Susceptible and -Resistant Humanized Mice

Rheumatoid arthritis (RA) is an autoimmune disease marked by chronic synovial inflammation and both, genetic and environmental factors are involved in its pathogenesis. Human leukocyte antigen (HLA) DRB1*0401 is associated with susceptibility to develop RA, while cigarette smoke (CS) exposure promotes seropositive disease with increased severity in DRB1*0401+ individuals. Smokers have higher levels of antibodies against citrullinated peptides. In this study, we determined whether the response to a known autoantigen, Vimentin (Vim) is shared epitope specific and how CS influences this response using transgenic-mice carrying RA-susceptible,*0401, and -resistant, *0402, genes. Following relatively brief exposure to CS, peptidyl arginine deiminase (PAD) enzyme expression was increased in murine lungs. Cigarette smoking led to production of Interferon (IFN)-γ with reduced levels of Interleukin (IL)-10 by splenocytes of *0401 mice. In contrast, CS augmented Th2 cytokines along with T-regulatory cells in *0402 mice. An increase in levels of antibodies to native and citrullinated Vim was observed in naïve mice of both strains following CS exposure. Our data showed that both arthritis-susceptible and -resistant mice can generate cellular and humoral immunity to Vim; however CS-induced modulation of host immunity is dependent on the interaction with the host HLA genes.

Gut microbiota dysbiosis in patients with Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory and demyelinating autoimmune disease that is known to involve environmental predisposition—an important component of which may be influenced by the GI microbiota. This study was designed to investigate whether gut microbiota may play a role in the etiopathogenesis of MS, by comparing the composition of fecal microbiota in MS patients to that of age- and gender-matched healthy controls. Phylotype profiles of the microbiome populations were generated using deep sequencing of the hyper variable V3–V5 region of the 16S ribosomal RNA (rRNA) gene and high quality sequences were then analyzed for taxonomic composition and clustering (OTU) using QIIME (Quantitative Insights Into Microbial Ecology) and LEfSe (LDA Effect Size). High-throughput multiplexed MiSeq sequencing yielded over 50,000 reads/sample, ensuring detection of both dominant and rare members of the microbiome. Detailed fecal microbiome analyses revealed that patients with MS had a distinct microbial community profile compared to healthy controls. We observed a decreased abundance of taxa involved in metabolism of phytoestrogen and bile acid, both of which play important roles in the maintenance of gut homeostasis and the induction of anti-inflammatory pathways. This study suggests that microbial dysbiosis, particularly a decrease in anti-inflammatory microbes, may lead to an increased pro-inflammatory immune response and subsequent predisposition to the development of MS. In particular, our study consistent with the hypothesis that microbial dysbiosis is a contributing environmental factor involved in the etiopathogenesis of MS.

The gut microbiome in autoimmunity: Sex matters

Autoimmune diseases like rheumatoid arthritis are multifactorial in nature, requiring both genetic and environmental factors for onset. Increased predisposition of females to a wide range of autoimmune diseases points to a gender bias in the multifactorial etiology of these disorders. However, the existing evidence to date has not provided any conclusive mechanism of gender-bias beyond the role of hormones and sex chromosomes. The gut microbiome, which impacts the innate and adaptive branches of immunity, not only influences the development of autoimmune disorders but may interact with sex-hormones to modulate disease progression and sex-bias. Here, we review the current information on gender bias in autoimmunity and discuss the potential of microbiome-derived biomarkers to help unravel the complex interplay between genes, environment and hormones in rheumatoid arthritis.

Identification of genes/pathways responsible for resistance vs susceptibility to EAE utilizing HLA class-II transgenic mice (BA8P.163)

MS is an autoimmune disease of the CNS and among all the genetic factors; MHC class-II molecules show the strongest association. To better understand the role of MHC class-II (HLA-DR/DQ) genes in susceptibility and resistance to MS, we utilized transgenic (Tg) mice expressing HLA class-II gene lacking endogenous mouse class II genes. HLA-DR3 Tg mice are susceptible to PLP91-110 induced experimental autoimmune encephalomyelitis (EAE), whereas DQ8 (DQB1*0302) transgenic mice are resistant. To identify the gene expression changes and pathways required for disease susceptibility vs resistance to EAE, we performed mRNA expression profiling of CD4+ T cells from HLA-DR3 (susceptible) and HLA-DQ8 (resistant) Tg mice. Whole genome expression analysis identified 2945 genes in HLA-DR3 Tg mice (PLP91-110 immunized vs. naïve) and 1053 genes in HLA-DQ8 Tg mice (PLP91-110 immunized vs. naïve). Comparison of modulated genes between DR3 and DQ8 identified 772 genes common to both strains, 2173 genes unique to DR3 whereas 281 genes were unique to DQ8 mice. Ingenuity pathway analysis showed up regulation of pathways involved in T cell signaling in inflammation, NF-kB signaling and those responsible for communication between innate and adoptive immunity. Majority of these pathways have IL1β as a major upstream regulator in disease susceptible HLA-DR3 Tg mice. Thus microarray data indicates an important role of IL1β induced encephalitogenic T helper cell differentiation in disease susceptibility.

Modulation of Immune response by Ultra-violet light in HLA class-II transgenic mice

Multiple Sclerosis (MS) is a chronic and debilitating disease of the central nervous system linked to both genetic and environmental factors. Among the genetic factors, MHC, especially HLA class-II, is strongly associated with predisposition to MS. Although in vitro studies have helped us understand some aspects of HLA class-II association with the disease, performing in vivo analysis is necessary in order to further understand this correlation. Studying the role of class-II genes in vivo is a difficult task due to the heterogeneity of human population, the complexity of MHC, and the strong linkage disequilibrium among different class-II genes. To overcome this challenge, we generated HLA class-II transgenic mice to study the role of these molecules in MS. Among the environmental factors linked with MS, ultra violet radiation (UVR)/vitamin-D is suggested to have protective effect against the development of the disease. Indeed, genetic studies have shown that presence of susceptible HLA-Class II and decrease in UVR exposure or vitamin D levels together increase risk of MS. Therefore, this study was designed to investigate the direct effect of UVR on immune response using novel humanized HLA-class II transgenic mice. HLA-class II transgenic mice expressing MS susceptible HLA-DR2 allele were treated with different doses of UVR (0.50-3.75 kJ/day) for seven consecutive days. T-cell proliferation, immune cell sub-populations and cytokines levels were analyzed. Our results show that treatment with UVR increased levels of regulatory CD4+FoxP3+ T cells and Gr1+ CD11b+ suppressive macrophages. Thus our study indicates that UVR modulates the immune response towards a tolerogenic phenotype in HLA-transgenic mice immunized with MOG_35-55. Therefore, HLA class-II transgenic mice offer a novel tool to decipher the mechanism by which interaction between environmental and genetic factors play a role in predisposition and/or protection against development of MS.

Absence of IFN-γ increases brain pathology in experimental autoimmune encephalomyelitis-susceptible DRB1*0301.DQ8 HLA transgenic mice through secretion of proinflammatory cytokine IL-17 and induction of pathogenic monocytes/microglia into the central nervous system

Multiple sclerosis is an inflammatory, demyelinating disease of the CNS of presumed autoimmune origin. Of all the genetic factors linked with multiple sclerosis, MHC class II molecules have the strongest association. Generation of HLA class II transgenic (Tg) mice has helped to elucidate the role of HLA class II genes in chronic inflammatory and demyelinating diseases. We have shown that the human HLA-DRB1*0301 gene predisposes to proteolipid protein (PLP)-induced experimental autoimmune encephalomyelitis (EAE), whereas HLA-DQβ1*0601 (DQ6) was resistant. We also showed that the DQ6 molecule protects from EAE in DRB1*0301.DQ6 double-Tg mice by producing anti-inflammatory IFN-γ. HLA-DQβ1*0302 (DQ8) Tg mice were also resistant to PLP(91-110)-induced EAE, but production of proinflammatory IL-17 exacerbated disease in DRB1*0301.DQ8 mice. To further confirm the role of IFN-γ in protection, we generated DRB1*0301.DQ8 mice lacking IFN-γ (DRB1*0301.DQ8.IFN-γ(-/-)). Immunization with PLP(91-110) peptide caused atypical EAE in DRB1*0301.DQ8.IFN-γ(-/-) mice characterized by ataxia, spasticity, and dystonia, hallmarks of brain-specific disease. Severe brain-specific inflammation and demyelination in DRB1*0301.DQ8.IFN-γ(-/-) mice with minimal spinal cord pathology further confirmed brain-specific pathology. Atypical EAE in DRB1*0301.DQ8.IFN-γ(-/-) mice was associated with increased encephalitogenicity of CD4 T cells and their ability to produce greater levels of IL-17 and GM-CSF compared with DRB1*0301.DQ8 mice. Further, areas with demyelination showed increased presence of CD68(+) inflammatory cells, suggesting an important role for monocytes/microglia in causing brain pathology. Thus, our study supports a protective role for IFN-γ in the demyelination of brain through downregulation of IL-17/GM-CSF and induction of neuroprotective factors in the brain by monocytes/microglial cells.

DRB1*0402 may influence arthritis by promoting naive CD4+ T-cell differentiation in to regulatory T cells

HLA-DRB1*0401 expression in humans has been associated with a predisposition to developing rheumatoid arthritis (RA) and collagen-induced arthritis (CIA), while HLA-DRB1*0402 is not associated with susceptibility. Here, we determined if mice transgenic (Tg) for human *0401 have a CD4+ T-cell repertoire that predetermines proinflammatory cytokine production. The data show that both *0401 and *0402 Tg mice can produce TH1/TH17 cytokines, although the kinetics of response may be different. However, in the context of antigen-specific responses in a CIA model, *0402 Tg mice generate a TH2 response that may explain their resistance to developing arthritis. In addition, a significant subset of naïve CD4+ T cells from *0402 Tg mice can be activated in polarizing conditions to differentiate into Treg cells that produce IFN-γ. *0401 Tg mice harbor memory CD4+ T cells that differentiate into IL-17(+) cells in various polarizing conditions. Our data suggest that *0401 Tg mice generate a strong immune response to lipopolysaccharide and may be efficient in clearing infection, and may *0401 have been evolutionarily selected for this ability. Autoimmunity, such as RA, could likely be a bystander effect of the cytokine storm that, along with the presence of low Treg-cell numbers in *0401 Tg mice, causes immune dysregulation.

Absence of IFNγ increased brain pathology in EAE-susceptible DR3DQ8 HLA transgenic mice through secretion of IL-17 and induction of pathogenic monocytes/microglia into the CNS (BA14P.202)

Among all the genetic factors linked with multiple sclerosis (MS), MHC class-II molecules show the strongest association. Generation of HLA class-II transgenic mice has helped to elucidate the role of HLA class-II gene in MS. We have shown that the human HLA-DR3 (DRβ1*0301) gene predisposes to proteolipid protein (PLP)-induced EAE, whereas HLA-DQβ1*0601 (DQ6) was resistant. We also showed that the DQ6 molecule protects from EAE in DR3DQ6 double transgenic mice by producing anti-inflammatory interferon gamma (IFNγ). To further confirm the role of IFNγ in protection, we generated DR3DQ8 mice lacking IFNγ (DR3DQ8.IFNγ-/-). Immunization with PLP91-110 peptide caused atypical EAE in DR3DQ8.IFNγ-/- mice characterized by ataxia and spasticity, hallmarks of brain-specific disease. Severe brain specific inflammation and demyelination in DR3DQ8.IFNγ-/- mice with minimal spinal cord pathology further confirmed brain-specific pathology. Severe disease in DR3DQ8.IFNγ-/- mice was due to increased encephalitogenicity of CD4 T cells and its ability to produce higher levels of IL-17 and GM-CSF compared to DR3DQ8 mice. Further, areas with demyelination showed increased presence of CD68+ inflammatory cells suggesting an important role for monocytes/microglia in causing brain pathology. Thus, our study supports a protective role for IFNγ in inflammatory and demyelinating disease through down regulation of IL-17 and induction of neuro-protective factors in the brain by monocytes/microglial cells.

Cellular and humoral immunity in arthritis are profoundly influenced by the interaction between cigarette smoke effects and host HLA-DR and DQ genes

Individuals carrying DRB1*0401 who smoke cigarettes are at an increased risk of developing severe seropositive RA. To determine how cigarette smoke (CS) interacts with host genetic factors in the induction of RA-associated autoimmunity, we used transgenic mice carrying the RA-susceptible HLA genes DR4 and DQ8, but lacking all endogenous murine class II molecules. Cigarette smoke exposure augmented peptidylarginine deiminase (PAD) enzyme expression, and enhanced immune responses to citrullinated collagen and vimentin. Here we show for the first time that DQ molecules can present citrullinated peptides much more efficiently than native peptides. Interestingly, CS exposure suppressed collagen-induced arthritis (CIA) in DRB1*0401 mice although innate immune response was enhanced. On the other hand, CS exposure exacerbated CIA in DQ8 mice, which was accompanied by an increased expression of Th17 gene transcripts in lungs. These observations suggest that cigarette smoke promotes antigen-specific autoimmunity that is profoundly influenced by host genetic factors.

Bugs & us: the role of the gut in autoimmunity

Rheumatoid arthritis (RA) is a multifactorial disease and requires interaction between genetic and environmental factors for predisposition. The presence of bacterial DNA of the gut residing commensals in synovium as well as dysbiosis of certain commensal bacteria in faecal samples of RA patients as compared to controls suggest a significant role of the gut flora in pathogenesis of RA. The gut commensals are involved in host immune development and function suggesting they might be critical epigenetic factors modifying autoimmune diseases like RA. This raises the question if gut-derived commensal can be exploited to generate a biomarker profile along with genetic factors to define individuals at risk. Genomic wide association studies have confirmed the HLA (human leukocyte antigen) class II genes as the strongest risk factor for predisposition to RA. HLA-DQ8 and DRB1FNx010401 molecules predispose to develop arthritis while DRB1FNx010402 provides protection. Interaction between host genetic factors like major histocompatibility complex (MHC) and gut microbiota and its impact on the development of RA is difficult to study in humans due to high variability in the genetic factors and diet. Animal models provide a means to study the molecular basis of pathogenesis thereby providing a basis for developing therapeutic strategies. Using transgenic mice expressing RA-associated and resistant HLA genes, we have developed a collagen-induced arthritis (CIA) model that shares similarities with human disease in sex-bias, autoantibody profile and phenotype. Studies in transgenic mice suggest that arthritis-susceptibility may be associated with dysbiosis in the gut microbiome. Studies in animal models underscore the impact of the gut flora in extra-intestinal diseases. Exploring the role of gut microbes will significantly advance our understanding of RA pathogenesis and may further help develop strategies for mucosal modulation of RA.

Shared epitope impacts arthritis by influencing CD4 T cell differentiation (P3321)

HLA-DRB1*0401 has been associated with predisposition to develop rheumatoid arthritis (RA) while *0402 has been linked with resistance to develop RA. Using transgenic mice, we showed that *0401 mice are susceptible to develop collagen-induced arthritis (CIA) that mimics human disease in histopathology, production of autoantibodies and sex-bias while *0402 mice are not susceptible. In this study, we determined if *0401 mice have CD4 T cell repertoire that is predetermined to produce proinflammatory cytokines. The data shown here supports that both *0401 and *0402 mice can produce Th1/TH17 cytokines although conditions required for production of Th17 cytokines differ between the 2 strains. In context of CIA, *0402 mice generate a Th2 response that may explain its resistance to develop CIA. Further, our data supports that a significant subset of naïve CD4 T cells when activated in polarizing conditions can generate T regulatory cells in *0402 but not *0401 mice. We hypothesize that *0401 has been evolutionarily selected due to its ability to clear infection. Our data suggests that *0401 generates a storm of cytokines in response to bacterial products and may be more efficient in clearing infection than *0402. Autoimmunity is a bystander effect of the cytokine storm ensuing immune dysregulation along with the presence of lower number of T regulatory cells in *0401 mice.

B cells as effectors and regulators of sex-biased arthritis

B cells have been implicated both with pathogenic as well as protective capabilities in induction and regulation of autoimmune diseases. Rheumatoid arthritis (RA) is an autoimmune disease that occurs more often in women than men. A significant role of B cells as antibody producing and antigen-presenting cells has been demonstrated in RA. Predisposition to RA is associated with the presence of certain HLA class II alleles that share sequences with DRB1*0401. To determine the role of HLA genes and B cells in vivo, we have generated transgenic mice carrying HLA genes, DRB1*0401 and DQ8, known to be associated with susceptibility to RA. Humanized mice can be induced to develop arthritis that mimics human disease in clinical, histopathological and sex bias. Effect of hormones on immune cells and their function has been described in humans and mice and has been suggested to be the major reason for female bias of autoimmune diseases. An immune response to an antigen requires presentation by HLA molecules thus suggesting a critical role of MHC in combination with sex hormones in susceptibility to develop rheumatoid arthritis. Based on our observations, we hypothesize that modulation of B cells by estrogen, presentation of modified antigens by DR4 and production of antigen-specific B cell modulating cytokines leads to autoreactivity in females. These data suggest that considering patient's sex may be crucial in selecting the optimal treatment strategy. Humanized mice expressing RA susceptible and resistant haplotype provide a means to investigate mechanism sex-bias of arthritis and future strategies for therapy.

Loss of sex and age driven differences in the gut microbiome characterize arthritis-susceptible 0401 mice but not arthritis-resistant 0402 mice

Background

HLA-DRB1*0401 is associated with susceptibility, while HLA-DRB1*0402 is associated with resistance to developing rheumatoid arthritis (RA) and collagen-induced arthritis in humans and transgenic mice respectively. The influence of gut-joint axis has been suggested in RA, though not yet proven.

Methodology/Principal Findings

We have used HLA transgenic mice carrying arthritis susceptible and -resistant HLA-DR genes to explore if genetic factors and their interaction with gut flora gut can be used to predict susceptibility to develop arthritis. Pyrosequencing of the 16S rRNA gene from the fecal microbiomes of DRB1*0401 and DRB1*0402 transgenic mice revealed that the guts of *0401 mice is dominated by a Clostridium-like bacterium, whereas the guts of *0402 mice are enriched for members of the Porphyromonadaceae family and Bifidobacteria. DRB1*0402 mice harbor a dynamic sex and age-influenced gut microbiome while DRB1*0401 mice did not show age and sex differences in gut microbiome even though they had altered gut permeability. Cytokine transcripts, measured by rtPCR, in jejuna showed differential TH17 regulatory network gene transcripts in *0401 and *0402 mice.

Conclusions/Significance

We have demonstrated for the first time that HLA genes in association with the gut microbiome may determine the immune environment and that the gut microbiome might be a potential biomarker as well as contributor for susceptibility to arthritis. Identification of pathogenic commensal bacteria would provide new understanding of disease pathogenesis, thereby leading to novel approaches for therapy.

To B or not to B: role of B cells in pathogenesis of arthritis in HLA transgenic mice

Population studies have shown that amongst all the genetic factors linked with autoimmune disease development, MHC class II genes are the most significant. Experimental autoimmune arthritis resembling human rheumatoid arthritis (RA) can be induced in susceptible strains of mice following immunization with type II collagen (CIA). We generated transgenic mice lacking endogenous class II molecules and expressing various HLA genes including RA-associated, HLA-DRB1*0401 and HLA-DQ8, and RA-resistant, DRB1*0402, genes. The HLA molecules in these mice are expressed on the cell surface and can positively select CD4+ T cells expressing various Vβ T cell receptors. Endogenous class II invariant chain is required for proper functioning of the class II transgene. Arthritis development in transgenic mice is CD4+ and B cells dependent. Studies in humanized mice showed that B cells are required as antigen presenting cells in addition to antibody producing cells for the development of CIA. The transgenic mice expressing *0401 and *0401/DQ8 genes developed sex-biased arthritis with predominantly females being affected, similar to that of human RA. Further, the transgenic mice produced autoantibodies like rheumatoid factor and anti-cyclic antibodies. Antigen presentation by B cells leads to a sex-specific immune response in DRB1*0401 mice suggesting a role of B cells and HLA-DR in rendering susceptibility to develop arthritis in females.

HLA-DQ8 (DQB1*0302)-restricted Th17 cells exacerbate experimental autoimmune encephalomyelitis in HLA-DR3-transgenic mice

Among all of the genetic factors associated with multiple sclerosis (MS) susceptibility, MHC class II molecules have the strongest association. Although a direct role of DR alleles in MS have been confirmed, it has been difficult to understand the role of DQ alleles in disease pathogenesis due to strong linkage disequilibrium with certain DR alleles. Population studies have indicated that DQ alleles may play a modulatory role in progression of MS. Using HLA class II transgenic (Tg) mice, we investigated gene complementation between DR and DQ genes in the disease process. Previously, using single Tg mice (expressing HLA-DR or DQ gene), we showed that PLP(91-110) peptide induced experimental autoimmune encephalomyelitis (EAE) only in DR3.Abeta degrees mice, suggesting that DR3 (DRB1*0301) is a disease susceptibility gene in the context of PLP. We also showed that DQ6 protects development of EAE in DQ6/DR3 double Tg mice by production of anti-inflammatory IFN-gamma. In this study, we investigated the ability of DQ8 to modulate disease in DR3/DQ8 double Tg mice. Introduction of DQ8 onto DR3 Tg mice led to higher disease incidence and increased disease severity on immunization with PLP(91-110), indicating that DQ8 had an exacerbating effect on the development of EAE. Increased susceptibility in DR3/DQ8 Tg mice was due to increased production of proinflammatory cytokine IL-17 by DQ8-restricted T cells. HLA-DR3/DQ8 mice with EAE also demonstrated increased inflammation and demyelination in CNS as compared with single DR3 Tg mice. Thus double Tg mouse provides a novel model to study epistatic interactions between HLA class II molecules in inflammatory and demyelinating disease.

Dual role of CD8+ T cells in PLPp91-110 induced experimental autoimmune encephalomyelitis in HLA-DR3.Abo transgenic mice (99.1)

MS is an inflammatory demyelinating disease of CNS with a presumed autoimmune origin. Prevalent data from animal model of disease, experimental autoimmune encephalomyelitis (EAE) suggests that myelin-specific CD4 T-cells play a major role in disease. Role of CD8 T-cells in MS/EAE has been enigmatic as it has been assigned either regulatory or pathogenic role in disease. Previously we have shown that PLPp91-110 peptide can induce inflammatory neurological disease in HLA-DR3 transgenic (Tg) mice. In order to understand the role of CD8 T cells in this humanized model, we generated HLA-DR3 Tg mice lacking CD8 T cells (DR3.CD8-/-). These mice showed earlier onset and more severe disease when compared to CD8 sufficient HLA-DR3 Tg mice indicating that CD8 T-cells plays a regulatory role. However, pathological analysis of DR3.CD8-/- mice with EAE showed less inflammation and demyelination in CNS compared to DR3.CD8 sufficient mice suggesting a second pathogenic role of CD8 T cells. Thus, our data suggests both a regulatory as well as a pathogenic role of CD8 T cells in EAE and possibly in MS. We have characterized both subsets in detail and show that CD8+CD122- T cells are regulatory subset of CD8 T cells and suppress CD4 T cells by inhibiting antigen presentation pathway, while CD8+CD122- T cells are pathogenic subset. Thus ours is the first study to show a dual role of CD8 T cells in the onset, incidence, progression, severity and pathogenesis of EAE/MS.

HLA-DQ6 (DQB1*0601)-restricted T cells protect against experimental autoimmune encephalomyelitis in HLA-DR3.DQ6 double-transgenic mice by generating anti-inflammatory IFN-gamma

The human MHC class II genes are associated with genetic susceptibility to multiple sclerosis (MS), a chronic inflammatory demyelinating disease of the CNS of presumed autoimmune origin. These genes encode for proteins responsible for shaping immune response. The exact role of HLA-DQ and -DR genes in disease pathogenesis is not well-understood due to the high polymorphism, linkage disequilibrium, and heterogeneity of human populations. The advent of HLA class II-transgenic (Tg) mice has helped in answering some of these questions. Previously, using single-Tg mice (expressing the HLA-DR or -DQ gene), we showed that proteolipid protein (PLP)(91-110) peptide induced classical experimental autoimmune encephalomyelitis only in DR3.Abeta degrees mice, suggesting that DR3 (DRB1*0301) is a disease susceptible gene in the context of PLP. Human population studies have suggested that HLA-DQ6 (DQB1*0601) may be a protective gene in MS. To test this disease protection in an experimental model, we generated double-Tg mice expressing both HLA-DR3 and -DQ6. Introduction of DQ6 onto DR3-Tg mice led to a decrease in disease incidence on immunization with PLP(91-110) peptide indicating a dominant protective role of DQ6. This protective effect is due to high levels of IFN-gamma produced by DQ6-restricted T cells, which suppressed proliferation of encephalitogenic DR3-restricted T cells by inducing apoptosis. Our study indicates that DQ6 modifies the PLP(91-110)-specific T cell response in DR3 through anti-inflammatory effects of IFN-gamma, which is protective for experimental autoimmune encephalomyelitis. Thus, our double-Tg mouse provides a novel model in which to study epistatic interactions between HLA class II molecules in MS.

Long-term effects of nurse home visitation on children's criminal and antisocial behavior: 15-year follow-up of a randomized controlled trial

CONTEXT

A program of home visitation by nurses has been shown to affect the rates of maternal welfare dependence, criminality, problems due to use of substances, and child abuse and neglect. However, the long-term effects of this program on children's antisocial behavior have not been examined.

OBJECTIVE

To examine the long-term effects of a program of prenatal and early childhood home visitation by nurses on children's antisocial behavior.

DESIGN

Fifteen-year follow-up of a randomized trial. Interviews were conducted with the adolescents and their biological mothers or custodial parents.

SETTING

Semirural community in New York.

PARTICIPANTS

Between April 1978 and September 1980, 500 consecutive pregnant women with no previous live births were recruited, and 400 were enrolled. A total of 315 adolescent offspring participated in a follow-up study when they were 15 years old; 280 (89%) were born to white mothers, 195 (62%) to unmarried mothers, 151 (48%) to mothers younger than 19 years, and 186 (59%) to mothers from households of low socioeconomic status at the time of registration during pregnancy.

INTERVENTION

Families in the groups that received home visits had an average of 9 (range, 0-16) home visits during pregnancy and 23 (range, 0-59) home visits from birth through the child's second birthday. The control groups received standard prenatal and well-child care in a clinic.

MAIN OUTCOME MEASURES

Children's self-reports of running away, arrests, convictions, being sentenced to youth corrections, initiation of sexual intercourse, number of sex partners, and use of illegal substances; school records of suspensions; teachers' reports of children's disruptive behavior in school; and parents' reports of the children's arrests and behavioral problems related to the children's use of alcohol and other drugs.

RESULTS

Adolescents born to women who received nurse visits during pregnancy and postnatally and who were unmarried and from households of low socioeconomic status (risk factors for antisocial behavior), in contrast with those in the comparison groups, reported fewer instances (incidence) of running away (0.24 vs 0.60; P = .003), fewer arrests (0.20 vs 0.45; P = .03), fewer convictions and violations of probation (0.09 vs 0.47; P<.001), fewer lifetime sex partners (0.92 vs 2.48; P= .003), fewer cigarettes smoked per day (1.50 vs 2.50; P= .10), and fewer days having consumed alcohol in the last 6 months (1.09 vs 2.49; P = .03). Parents of nurse-visited children reported that their children had fewer behavioral problems related to use of alcohol and other drugs (0.15 vs 0.34; P = .08). There were no program effects on other behavioral problems.

CONCLUSIONS

This program of prenatal and early childhood home visitation by nurses can reduce reported serious antisocial behavior and emergent use of substances on the part of adolescents born into high-risk families.

High frequency of Gag- and envelope-specific cytotoxic T lymphocyte precursors in children with vertically acquired human immunodeficiency virus type 1 infection

Circulating human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T lymphocytes (CTL) are seen less frequently in unstimulated peripheral blood mononuclear cells (PBMC) from children with vertically acquired HIV infection than in PBMC from HIV-infected adults. HIV-1 Gag-, reverse transcriptase (RT)-, and envelope (Env)-specific cytotoxic activity was studied in PBMC from HIV-infected children. Only 9% of subjects had Gag- or RT-specific CTL in unstimulated PBMC. However, in PBMC studied after CD3 stimulation, Gag- and Env-specific CTL were found in PBMC from 91% and 78% of HIV-infected children, respectively. Limiting dilution analysis of precursor CTL (pCTL) frequencies in PBMC from children > 12 months old demonstrated Gag- and Env-specific pCTL frequencies from 0.5 to 6.3/10,000 PBMC and from 0.66 to 33.0/10,000 PBMC, respectively. Thus, children with vertically acquired HIV infection have high frequencies of HIV-specific pCTL.

Theoretical cost effectiveness of management options for children with persisting middle ear effusions

OBJECTIVE

The purpose of this theoretical study is to assess the cost effectiveness of options involving observation, antibiotics alone, corticosteroids alone, corticosteroids plus antibiotics, and surgery to clear persisting middle ear effusions during three visits.

METHODOLOGY

In a hypothetical case the expected average per patient expenditures are calculated using the efficacy rates determined by the meta-analysis of randomized controlled clinical trials involving corticosteroids plus an antibiotic (six trials), corticosteroids alone (three trials), and antibiotic alone (four trials). In this analysis, all children whose bilateral middle ear effusions persist for 12 weeks despite medical management are referred for ventilating tubes.

RESULTS

The most cost-effective intervention combination is corticosteroid plus an antibiotic at visit 1 (6 weeks after diagnosis of acute otitis media) followed by a second antibiotic in nonresponders at visit 2 (9 weeks after diagnosis of acute otitis media) and referral for ventilating tubes in nonresponders at visit 3 (12 weeks after diagnosis of acute otitis media). The expected average expenditures per case to clear the bilateral middle ear effusions is $600.91 based on reimbursement of private practice charges and $350.27 based on Medicaid reimbursement (all payments to providers are based on 1992 data from Colorado). The difference in the expected average total expenditures per case between this most cost-effective approach versus the use of sequential courses of antibiotics followed by surgery is $372.81 ($973.72-$600.91) with full reimbursement of private practice charges and $202.57 ($552.84-$350.27) with Medicaid reimbursement. In clearing the middle ear effusion, the average estimated travel expenses per case is $21.46, and lost parental wages per case are $45.12. When the expenditures associated with an additional 6-month follow-up period are included, the expected average per case expenditures is $1088.54 with reimbursement of private practice charges and @659.00 with Medicaid reimbursement. The difference in the expected average per case expenditures to clear the effusions and follow-up for 6 months between the most cost-effective approach using corticosteroids plus antibiotics at the 6- and 9-week visits followed by surgery in nonresponders at 12 weeks versus sequential courses of antibiotics is $405.30 ($1493.84-$1088.54) with reimbursement of private practice charges and $217.32 ($876.32-$659.00) with Medicaid reimbursement.

RECOMMENDATIONS

Although the analysis does not consider risks, side effects, and parental or provider preferences, the findings suggest that the implementation of cost-effective clinical guidelines can potentially reduce national expenditures for managing persistent middle ear effusions.

Saturation by pulse oximetry: comparison of the results obtained by instruments of different brands

We noticed that arterial oxygen saturation by pulse oximetry (SpO2) was generally lower when determined by the Ohmeda Biox 3700 pulse oximeter than when determined by the Nellcor N-100 pulse oximeter, and we investigated whether this finding was consistent and the reason for the discrepancy. We placed both oximeters simultaneously on 30 infants with indwelling arterial catheters and measured arterial partial pressure of oxygen (PaO2), percentage of fetal hemoglobin, and complete cooximetry, including arterial oxygen saturation (SaO2) with a Radiometer OSM-3 cooximeter, with and without correction for fetal hemoglobin levels, in four samples of blood from each infant during a 12-hour period for a total of 120 samples. The Nellcor SpO2 was consistently higher than the Ohmeda SpO2 by a mean (+/- SD) of 1.61% +/- 2.69% (p < 0.001). The Nellcor SpO2 correlated best with functional SaO2 (oxyhemoglobin (HbO2)/(HbO2 + reduced hemoglobin)) x 100); Ohmeda SpO2 correlated best with fractional SaO2 (HbO2/(HbO2 + reduced hemoglobin + carboxyhemoglobin + methemoglobin)) x 100), reflecting a fundamental difference in the calibration algorithms used in the two instruments. A desired PaO2 of 50 to 100 mm Hg, is maintained when the range of SpO2 is 90% to 96% for Ohmeda SpO2 and 92% to 98% for Nellcor SpO2 in the neonate, giving a positive predictive value in this study of 94% to 95%. We conclude that SpO2 determined by pulse oximeters of different brands is not interchangeable, and this may be of clinical importance in predicting PaO2 on the basis of SpO2.

Hip flexion contracture in cerebral palsy. The association between clinical and radiologic measurement methods

Hip flexion contracture was examined in 51 spastic cerebral palsy patients by three clinical methods and two radiologic methods. An extremely low association was found between the clinical and radiologic methods with no particular method, clinical or radiologic, showing a higher association. The method of clinical examination should be chosen by convenience. Radiologic measurements by the methods used did not add useful information.

Prediction of the need for transfusion during anemia of prematurity

We reviewed erythrocyte transfusions, given after 2 weeks of age to premature infants, to derive patient selection criteria for trials of administration of recombinant human erythropoietin to maintain hematocrit during the anemia of prematurity. We first studied 122 infants, less than 36 weeks of gestational age, who remained in a level 3 nursery longer than 4 weeks. Multiple logistic regression analysis was used to select those variables associated with more than two transfusions after the second week; these included gestational age, 5-minute Apgar score, transfusion during the first week, and patent ductus ligation. The best predictor, alone or combined, was gestational age less than 30 weeks. This predictor was applied to a second population of 44 premature infants from a level 2 nursery, and we found a 94% probability of excluding those infants who did not receive a transfusion. This information will allow selection of premature infants who are candidates for administration of recombinant human erythropoietin.

Intrauterine resuscitation with tocolysis. An alternate month clinical trial

Fifty patients were compared for the purpose of investigating the usefulness of intrauterine resuscitation with tocolysis (IURT). Terbutaline was given, as an intravenous bolus, to 31 women in labor in whom fetal distress was diagnosed and urgent delivery by cesarean section was indicated. In alternate months, a control group of 19 women with similar diagnoses was urgently delivered after standard interventions such as maternal positioning, oxygen administration, hydration, and discontinuation of oxytocin. Improvement in perinatal outcome was shown in infants after IURT. Apgar scores were less than 7 in 42% of the study group and in 71% of the control group at 1 minute (P = .04). Five-minute Apgar scores less than 7 occurred in 7% of the study group and 24% of the control group. A low venous pH was seen in 55% of the control group compared with 29% of the infants resuscitated with terbutaline. Estimated maternal blood loss and hematocrit change was not different in the two groups. Maternal blood pressure and pulse changes following IURT were modest and of doubtful significance. We conclude that intravenous terbutaline administered as a bolus injection at the time of fetal distress in labor improves infant outcome as evidenced by more vigorous Apgar scores and less acidemia without significant adverse physiologic effects on the mother.