T helper 2 (Th2) T cells induce acute pancreatitis and diabetes in immune-compromised nonobese diabetic (NOD) mice

Viral infection and host immune response in diabetes

Diabetes, a chronic metabolic disorder disrupting blood sugar regulation, has emerged as a prominent silent pandemic. Uncontrolled diabetes predisposes an individual to develop fatal complications like cardiovascular disorders, kidney damage, and neuropathies and aggravates the severity of treatable infections. Escalating cases of Type 1 and Type 2 diabetes correlate with a global upswing in diabetes-linked mortality. As a growing global concern with limited preventive interventions, diabetes necessitates extensive research to mitigate its healthcare burden and assist ailing patients. An altered immune system exacerbated by chronic hyperinflammation heightens the susceptibility of diabetic individuals to microbial infections, including notable viruses like SARS-CoV-2, dengue, and influenza. Given such a scenario, we scrutinized the literature and compiled molecular pathways and signaling cascades related to immune compartments in diabetics that escalate the severity associated with the above-mentioned viral infections in them as compared to healthy individuals. The pathogenesis of these viral infections that trigger diabetes compromises both innate and adaptive immune functions and pre-existing diabetes also leads to heightened disease severity. Lastly, this review succinctly outlines available treatments for diabetics, which may hold promise as preventive or supportive measures to effectively combat these viral infections in the former.

Pancreatic β-cell dysfunction in type 2 diabetes: Implications of inflammation and oxidative stress

Insulin resistance and pancreatic β-cell dysfunction are major pathological mechanisms implicated in the development and progression of type 2 diabetes (T2D). Beyond the detrimental effects of insulin resistance, inflammation and oxidative stress have emerged as critical features of T2D that define β-cell dysfunction. Predominant markers of inflammation such as C-reactive protein, tumor necrosis factor alpha, and interleukin-1β are consistently associated with β-cell failure in preclinical models and in people with T2D. Similarly, important markers of oxidative stress, such as increased reactive oxygen species and depleted intracellular antioxidants, are consistent with pancreatic β-cell damage in conditions of T2D. Such effects illustrate a pathological relationship between an abnormal inflammatory response and generation of oxidative stress during the progression of T2D. The current review explores preclinical and clinical research on the patho-logical implications of inflammation and oxidative stress during the development of β-cell dysfunction in T2D. Moreover, important molecular mechanisms and relevant biomarkers involved in this process are discussed to divulge a pathological link between inflammation and oxidative stress during β-cell failure in T2D. Underpinning the clinical relevance of the review, a systematic analysis of evidence from randomized controlled trials is covered, on the potential therapeutic effects of some commonly used antidiabetic agents in modulating inflammatory makers to improve β-cell function.

Evaluating the Immunopathogenesis of Diabetes After Acute Pancreatitis in the Diabetes RElated to Acute Pancreatitis and Its Mechanisms Study: From the Type 1 Diabetes in Acute Pancreatitis Consortium

ABSTRACT

The association between acute pancreatitis (AP) and diabetes mellitus (DM) has long been established, with the initial descriptions of AP patients presenting with DM after a bout of AP published in the 1940s and 50s. However, the potential mechanisms involved, particularly those components related to the immune system, have not been well defined. The Diabetes RElated to Acute pancreatitis and its Mechanisms (DREAM) study is a multicenter clinical study designed to understand the frequency and phenotype of DM developing after AP. This article describes one objective of the DREAM study: to determine the immunologic mechanisms of DM after AP, including the contribution of β-cell autoimmunity. This component of the study will assess the presence of islet autoimmunity, as well as the magnitude and kinetics of the innate and adaptive immune response at enrollment and during longitudinal follow-up after 1 or more episodes of AP. Finally, DREAM will evaluate the relationship between immune features, DM development, and pancreatitis etiology and severity.

Epigenetic drug ameliorated type 1 diabetes via decreased generation of Th1 and Th17 subsets and restoration of self-tolerance in CD4+ T cells

Female NOD mice develop autoimmune diabetes spontaneously without extrinsic manipulation. Previously, we have shown that weekly administration of the prediabetic female NOD mice with the histone modifier Trichostatin A (TSA) prevented diabetes onset. Herein we show that T lymphocytes from diabetic mice transferred diabetes into immunodeficient NOD.scid recipients while those isolated from drug-treated mice displayed reduced disease-causing ability. Drug treatment also repressed T cell receptor-mediated IFN-γ transcription. Splenic CD4⁺ T-cells purified from prediabetic mice could be polarized into IFN-γ -producing Th1 and IL-17A-expressing Th17 subsets ex vivo. Adoptive transfer of these cells into immunocompromised NOD.scid mice caused diabetes comparably. Polarized Th1 cells were devoid of IL-17A-producing cells and did not transdifferentiate into Th17 cells in the spleen of immunodeficient recipients. However, polarized Th17 cell preparation had a few contaminant Th1 cells. Adoptive transfer of polarized Th17 cells into NOD.scid recipients led to IFN-γ transcription in recipient splenocytes. Notably, TSA treatment of prediabetic mice abolished the ability of CD4⁺ T-cells to differentiate into diabetogenic Th1 and Th17 cells ex vivo. This was accompanied by the absence of Ifng and Il17a transcription in the spleen of NOD.scid recipients receiving cells, respectively cultured under Th1 and Th17 polarizing conditions. Significantly, the histone modifier restored the ability of CD4⁺ but not CD8⁺ T-cells to undergo CD3-mediated apoptosis ex vivo in a caspase-dependent manner. These results indicate that the histone modifier bestowed protection against type 1 diabetes via negative regulation of signature lymphokines and restitution of self-tolerance in CD4⁺ T cells.

Epigenetic modulation of selected immune response genes and altered functions of T lymphocytes and macrophages collectively contribute to autoimmune diabetes protection

We have previously demonstrated that weekly treatment of female prediabetic NOD mice with a low dose of the histone deacetylase inhibitor Trichostatin A (TSA) bestowed long-lasting, irreversible protection against autoimmune diabetes. Herein we show that drug treatment diminished the infiltration of the pancreas with CD4⁺, CD8⁺ T cells, and Ly-6C⁺ monocytes. Significantly, TSA administration selectively repressed the expression of a set of genes exaggerated during diabetes and constitutively expressed primarily in the spleen and rarely in the pancreas. These genes encode lymphokines, macrophage-associated determinants, and transcription factors. Although the copy numbers of many histone deacetylases increased during diabetes in the spleen and pancreas, only those upregulated in the spleen were rendered sensitive to repression by TSA treatment. Mitogen-activated T lymphocytes derived from drug-treated donors displayed diminished diabetogenic potential following transfer into immunodeficient NOD.scid mice. In the immunocompromised recipients, diabetes caused by the transfer of activated T lymphocytes from untreated diabetic mice was hampered by the co-transfer of highly purified splenic CD11b⁺Ly-6C⁺ macrophages from drug-treated mice. However, the transfer of CD11b⁺Ly-6C⁺ macrophages from drug-treated mice failed to block ongoing diabetes in wild-type NOD mice. These data demonstrate that the modified gene expression and functional alteration of T lymphocytes and macrophages collectively contribute to diabetes protection afforded by the histone modifier in female NOD mice.

Association of IL-10 gene (-1082A>G, -819C>T and -592C>A) polymorphism and its serum level with metabolic syndrome of north Indian subjects

Metabolic syndrome (MetS) is an inflammatory disorder, in which various cytokines play important role in tilting balance towards disease state. Interleukin-10 (IL-10) is an important antiinflammatory cytokine, but its genetic polymorphisms and serum levels in Indian MetS subjects are unknown. Three IL-10 gene polymorphisms (-1082A>G (rs1800896), -819C>T (rs1800872) and -592C>A (rs1800871)) were genotyped with PCR-RFLP in MetS subjects (n = 384) and age/sex matched control subjects (n = 386). Serum IL-10 was measured using enzyme-linked immunosorbent assay. Serum IL-10 level was significantly low in MetS subject and significantly correlated with clinicobiochemical parameters of MetS. Of three investigated promoter polymorphisms, IL-10 -819C> T and -592C>A were significantly associated with risk of MetS. The mutant alleles -819T and -592A of IL-10 gene polymorphism were significantly higher in MetS subjects compared to controls. Of the four different haplotypes obtained, common ACC haplotype and rare GTA haplotype of IL-10 polymorphisms were associated with MetS. The mean of fasting insulin and HOMA-IR were significantly different between the genotypes of both -819 C>T and -592C>A polymorphisms of IL-10 in MetS subjects. These results suggested that polymorphisms in IL-10 gene (-819C>T and -592C>A), haplotypes (ACC and GTA) and serum level are significantly associated with risk of MetS. IL- 10 -819C>T and -592C>A polymorphic variants are also significantly associated with insulin level and homeostasis model assessment-insulin resistance in north Indian MetS subjects.

Regulatory T Cells Control Th2-Dominant Murine Autoimmune Gastritis

Pernicious anemia and gastric carcinoma are serious sequelae of autoimmune gastritis (AIG). Our study indicates that in adult C57BL/6-DEREG mice expressing a transgenic diphtheria toxin receptor under the Foxp3 promoter, transient regulatory T cell (Treg) depletion results in long-lasting AIG associated with both H(+)K(+)ATPase and intrinsic factor autoantibody responses. Although functional Tregs emerge over time during AIG occurrence, the effector T cells rapidly become less susceptible to Treg-mediated suppression. Whereas previous studies have implicated dysregulated Th1 cell responses in AIG pathogenesis, eosinophils have been detected in gastric biopsy specimens from patients with AIG. Indeed, AIG in DEREG mice is associated with strong Th2 cell responses, including dominant IgG1 autoantibodies, elevated serum IgE, increased Th2 cytokine production, and eosinophil infiltration in the stomach-draining lymph nodes. In addition, the stomachs exhibit severe mucosal and muscular hypertrophy, parietal cell loss, mucinous epithelial cell metaplasia, and massive eosinophilic inflammation. Notably, the Th2 responses and gastritis severity are significantly ameliorated in IL-4- or eosinophil-deficient mice. Furthermore, expansion of both Th2-promoting IFN regulatory factor 4(+) programmed death ligand 2(+) dendritic cells and ILT3(+) rebounded Tregs was detected after transient Treg depletion. Collectively, these data suggest that Tregs maintain physiological tolerance to clinically relevant gastric autoantigens, and Th2 responses can be a pathogenic mechanism in AIG.

Mechanisms of autoimmunity in the non-obese diabetic mouse: effector/regulatory cell equilibrium during peak inflammation

Immune imbalance in autoimmune disorders such as type 1 diabetes may originate from aberrant activities of effector cells or dysfunction of suppressor cells. All possible defective mechanisms have been proposed for diabetes-prone species: (i) quantitative dominance of diabetogenic cells and decreased numbers of regulatory T cells, (ii) excessive aggression of effectors and defective function of suppressors, (iii) perturbed interaction between effector and suppressor cells, and (iv) variations in sensitivity to negative regulation. The experimental evidence available to date presents conflicting information on these mechanisms, with identification of perturbed equilibrium on the one hand and negation of critical role of each mechanism in propagation of diabetic autoimmunity on the other hand. In our analysis, there is no evidence that inherent abnormalities in numbers and function of effector and suppressor T cells are responsible for the immune imbalance responsible for propagation of type 1 diabetes as a chronic inflammatory process. Possibly, the experimental tools for investigation of these features of immune activity are still underdeveloped and lack sufficient resolution, in the presence of the extensive biological viability and functional versatility of effector and suppressor elements.

Reactivated CD4+Tm cells of T1D patients and siblings display an exaggerated effector phenotype with heightened sensitivity to activation-induced cell death

Dysfunction in effector memory has been proposed to contribute to autoimmunity in type 1 diabetes (T1D). Using a unique cohort of age- and sex-matched T1D patients, nonaffected siblings, and unrelated control children, we undertook a detailed analysis of proliferation, activation, effector responses, and apoptosis in reactivated CD4(+)Tm cells during T-cell receptor stimulation. Across cohorts, there was no difference in the proliferation of reactivated CD4(+)Tm cells. In T1D patients and siblings, CD4(+)Tm cells easily acquired the activated CD25(+) phenotype and effectively transitioned from a central (CD62L(+)Tcm) to an effector memory (CD62L(-)Tem) phenotype with an elevated cytokine "signature" comprising interferon (IFN)-γ and interleukin-10 in T1D patients and IFN-γ in siblings. This amplified Tem phenotype also exhibited an exaggerated immune shutdown with heightened sensitivity to activation-induced cell death and Fas-independent apoptosis. Apoptosis resulted in the elimination of one-half of the effector memory in T1D patients and siblings compared with one-third of the effector memory in control subjects. These data suggest genetic/environment-driven immune alteration in T1D patients and siblings that manifests in an exaggerated CD4(+)Tem response and shutdown by apoptosis. Further immunological studies are required to understand how this exaggerated CD4(+)Tem response fits within the pathomechanisms of T1D and how the effector memory can be modulated for disease treatment and/or prevention.

Different subsets of natural killer T cells may vary in their roles in health and disease

Natural killer T cells (NKT) can regulate innate and adaptive immune responses. Type I and type II NKT cell subsets recognize different lipid antigens presented by CD1d, an MHC class-I-like molecule. Most type I NKT cells express a semi-invariant T-cell receptor (TCR), but a major subset of type II NKT cells reactive to a self antigen sulphatide use an oligoclonal TCR. Whereas TCR-α dominates CD1d-lipid recognition by type I NKT cells, TCR-α and TCR-β contribute equally to CD1d-lipid recognition by type II NKT cells. These variable modes of NKT cell recognition of lipid-CD1d complexes activate a host of cytokine-dependent responses that can either exacerbate or protect from disease. Recent studies of chronic inflammatory and autoimmune diseases have led to a hypothesis that: (i) although type I NKT cells can promote pathogenic and regulatory responses, they are more frequently pathogenic, and (ii) type II NKT cells are predominantly inhibitory and protective from such responses and diseases. This review focuses on a further test of this hypothesis by the use of recently developed techniques, intravital imaging and mass cytometry, to analyse the molecular and cellular dynamics of type I and type II NKT cell antigen-presenting cell motility, interaction, activation and immunoregulation that promote immune responses leading to health versus disease outcomes.

Genetic polymorphisms of cytokine genes in type 2 diabetes mellitus

Diabetes mellitus is a combined metabolic disorder which includes hyperglycemia, dyslipidemia, stroke and several other complications. Various groups all over the world are relentlessly working out the possible role of a vast number of genes associated with type 2 diabetes (T2DM). Inflammation is an important outcome of any kind of imbalance in the body and is therefore an indicator of several diseases, including T2DM. Various ethnic populations around the world show different levels of variations in single nucleotide polymorphisms (SNPs). The present review was undertaken to explore the association of cytokine gene polymorphisms with T2DM in populations of different ethnicities. This will lead to the understanding of the role of cytokine genes in T2DM risk and development. Association studies of genotypes of SNPs present in cytokine genes will help to identify risk haplotype(s) for disease susceptibility by developing prognostic markers and alter treatment strategies for T2DM and related complications. This will enable individuals at risk to take prior precautionary measures and avoid or delay the onset of the disease. Future challenges will be to understand the genotypic interactions between SNPs in one cytokine gene or several genes at different loci and study their association with T2DM.

Cyclin D3 promotes pancreatic β-cell fitness and viability in a cell cycle-independent manner and is targeted in autoimmune diabetes

Type 1 diabetes is an autoimmune condition caused by the lymphocyte-mediated destruction of the insulin-producing β cells in pancreatic islets. We aimed to identify final molecular entities targeted by the autoimmune assault on pancreatic β cells that are causally related to β cell viability. Here, we show that cyclin D3 is targeted by the autoimmune attack on pancreatic β cells in vivo. Cyclin D3 is down-regulated in a dose-dependent manner in β cells by leukocyte infiltration into the islets of the nonobese diabetic (NOD) type 1 diabetes-prone mouse model. Furthermore, we established a direct in vivo causal link between cyclin D3 expression levels and β-cell fitness and viability in the NOD mice. We found that changes in cyclin D3 expression levels in vivo altered the β-cell apoptosis rates, β-cell area homeostasis, and β-cell sensitivity to glucose without affecting β-cell proliferation in the NOD mice. Cyclin D3-deficient NOD mice exhibited exacerbated diabetes and impaired glucose responsiveness; conversely, transgenic NOD mice overexpressing cyclin D3 in β cells exhibited mild diabetes and improved glucose responsiveness. Overexpression of cyclin D3 in β cells of cyclin D3-deficient mice rescued them from the exacerbated diabetes observed in transgene-negative littermates. Moreover, cyclin D3 overexpression protected the NOD-derived insulinoma NIT-1 cell line from cytokine-induced apoptosis. Here, for the first time to our knowledge, cyclin D3 is identified as a key molecule targeted by autoimmunity that plays a nonredundant, protective, and cell cycle-independent role in β cells against inflammation-induced apoptosis and confers metabolic fitness to these cells.

Association of IL-6, TNF-α and IL-10 gene polymorphisms with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic pro-inflammatory disorder characterized by chronic hyperglycemia and increased levels of circulating cytokines suggesting a causal role of inflammation in its etiology. Polymorphism of cytokine genes including interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and interleukin-10 (IL-10) were studied in T2DM patients as well as in normal healthy controls. Genomic DNA was isolated from both T2DM patients and controls followed by quantification and genotyping by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using suitable primers. The genotypic, allelic and carriage rate frequency distribution in patients and controls were analyzed by SPSS (version 15.0). Odd ratios with 95 % confidence interval was determined to describe the strength of association by logistic regression model. Double and triple combinations of genotypes were analyzed by χ(2) test. Gene-gene interaction and linkage disequilibrium tests were performed using SHEsis software. Individually, IL-6, TNF-α and IL-10 did not show any association. In double combination, IL-6 -597 GA and TNF-α -308 GG genotypes increased the risk up to 21 times and in triple combination IL-6 -597 AA, TNF-α -308 GG and IL-10 -592 CA increased the risk of T2DM up to 314 times. In gene-gene interaction allele 'A' of all studied polymorphisms increased the risk of T2DM up to 1.41 times. Our results suggest that individuals having a haplotype combination of AA, GG and CA for IL-6, TNF-α and IL-10 gene polymorphisms will have higher susceptibility and be at greater risk of developing T2DM.

Models of acute and chronic pancreatitis

Animal models of acute and chronic pancreatitis have been created to examine mechanisms of pathogenesis, test therapeutic interventions, and study the influence of inflammation on the development of pancreatic cancer. In vitro models can be used to study early stage, short-term processes that involve acinar cell responses. Rodent models reproducibly develop mild or severe disease. One of the most commonly used pancreatitis models is created by administration of supraphysiologic concentrations of caerulein, an ortholog of cholecystokinin. Induction of chronic pancreatitis with factors thought to have a role in human disease, such as combinations of lipopolysaccharide and chronic ethanol feeding, might be relevant to human disease. Models of autoimmune chronic pancreatitis have also been developed. Most models, particularly of chronic pancreatitis, require further characterization to determine which features of human disease they include.

Influence of the vitamin D plasma level and vitamin D-related genetic polymorphisms on the immune status of patients with type 1 diabetes: a pilot study

Vitamin D (VD) has been implicated in type 1 diabetes (T1D) by genetic and epidemiological studies. Individuals living in regions with low sunlight exposure have an increased T1D risk and VD supplementation reduced the risk in human individuals and mouse models. One possibility of how VD influences the pathogenesis of T1D is its immunomodulatory effect on dendritic cells (DC), which then preferentially activate regulatory T cells (T(regs) ). In the present pilot study, we collected blood samples from a small cohort of patients with T1D at baseline and months 6 and 12. VD-deficient patients were advised to supplement with 1000 IU/day VD. We found a considerable variation in the VD plasma level at baseline and follow-up. However, with higher VD plasma levels, a lower frequency of interleukin (IL)-4-producing CD8 T cells was observed. We further performed a comprehensive genotyping of 13 VD-related polymorphisms and found an association between VD plasma level and the genotype of the VD binding protein (DBP). The frequency of DC and T cell subsets was variable in patients of all subgroups and in individual patients over time. Nevertheless, we found some significant associations, including the 1,25-dihydroxyvitamin D(3) hydroxylase (CYP27B1) genotype with the frequency of DC subtypes. In summary, our preliminary results indicate only a limited influence of the VD plasma level on the immune balance in patients with T1D. Nevertheless, our pilot study provides a basis for a follow-up study with a larger cohort of patients.

Transcriptome analysis of epigenetically modulated genome indicates signature genes in manifestation of type 1 diabetes and its prevention in NOD mice

Classic genetic studies implicated several genes including immune response genes in the risk of developing type 1 diabetes in humans. However, recent evidence including discordant diabetes incidence among monozygotic twins suggested a role for epigenetics in disease manifestation. NOD mice spontaneously develop type 1 diabetes like humans and serve as an excellent model system to study the mechanisms of type 1 diabetes as well as the efficacy of maneuvers to manipulate the disease. Using this preclinical model, we have recently demonstrated that pharmacological inhibition of histone deacetylases can lead to histone hyperacetylation, selective up-regulation of interferon-γ and its transactivator Tbx21/Tbet, and amelioration of autoimmune diabetes. In the current study, we show that chromatin remodeling can render splenocytes incapable of transferring diabetes into immunodeficient NOD.scid mice. To elucidate the underlying mechanisms of drug-mediated protection against type 1 diabetes, we performed global gene expression profiling of splenocytes using high throughput microarray technology. This unbiased transcriptome analysis unraveled the exaggerated expression of a novel set of closely related inflammatory genes in splenocytes of acutely diabetic mice and their repression in mice cured of diabetes by chromatin remodeling. Analysis of gene expression by qRT-PCR using RNA derived from spleens and pancreata of cured mice validated the suppression of most of these genes, indicating an inverse correlation between the high levels of these inflammatory genes and protection against diabetes in NOD mice. In addition, higher-level expression of genes involved in insulin sensitivity, erythropoiesis, hemangioblast generation, and cellular redox control was evident in spleens of cured mice, indicating their possible contribution to protection against type 1 diabetes. Taken together, these results are consistent with the involvement of epistatic mechanisms in the manifestation of autoimmune diabetes and further indicate the utility of chromatin remodeling in curing this complex autoimmune disorder.

An interleukin-10 gene promoter polymorphism (-592A/C) associated with type 2 diabetes: a North Indian study

In this first report on the association of an IL-10 promoter polymorphism with type 2 diabetes mellitus in a North Indian population, the -592A/C SNP (rs1800872) was genotyped by PCR-RFLP and the IL-10 level measured using ELISA. Although no significant difference was observed in the genotypic frequencies (P = 0.657), diabetes patients carried a significantly higher number of A alleles at the -592 position, 25.6% (P < 0.001, odds ratio 0.887, 95% CI 0.670-1.184). Significant correlations were detected in postprandial glucose levels of CC-genotype patients and controls (P = 0.025), age and waist-hip ratio of CA patients and controls (P ≤ 0.001), and fasting glucose (P = 0.045) and low-density lipoprotein (P = 0.049) in all patients and controls. The serum IL-10 level was significantly higher in patients than in controls (P = 0.033). The polymorphism was significantly associated with disease incidence and its biochemical manifestations.

NKT Cell Subsets Can Exert Opposing Effects in Autoimmunity, Tumor Surveillance and Inflammation

The innate-like natural killer T (NKT) cells are essential regulators of immunity. These cells comprise at least two distinct subsets and recognize different lipid antigens presented by the MHC class I like molecules CD1d. The CD1d-dependent recognition pathway of NKT cells is highly conserved from mouse to humans. While most type I NKT cells can recognize αGalCer and express a semi-invariant T cell receptor (TCR), a major population of type II NKT cells reactive to sulfatide utilizes an oligoclonal TCR. Furthermore TCR recognition features of NKT subsets are also distinctive with almost parallel as opposed to perpendicular footprints on the CD1d molecules for the type I and type II NKT cells respectively. Here we present a view based upon the recent studies in different clinical and experimental settings that while type I NKT cells are more often pathogenic, they may also be regulatory. On the other hand, sulfatide-reactive type II NKT cells mostly play an inhibitory role in the control of autoimmune and inflammatory diseases. Since the activity and cytokine secretion profiles of NKT cell subsets can be modulated differently by lipid ligands or their analogs, novel immunotherapeutic strategies are being developed for their differential activation for potential intervention in inflammatory diseases.

Astragalus polysaccharides regulate T cell-mediated immunity via CD11c(high)CD45RB(low) DCs in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Astragalus polysaccharides (APS) isolated from one of the Chinese herbs, Astragalus mongholicus, are known to have a variety of immunomodulatory activities. However, it is not yet clear whether APS can induce the activation and differentiation of dendritic cells (DCs) and subsequently activate T cells.

AIM OF THE STUDY

This study was carried out to investigate the effect of APS on the differentiation of splenic DCs and its influence on T cell-mediated immunity through interleukin (IL)-12-producing CD11c(high)CD45RB(low) DCs in vitro.

METHODOLOGY

MACS microbeads were used to isolate splenic DCs, CD11c(high)CD45RB(low) DCs, CD11c(low)CD45RB(high) DCs and CD4(+) T cells. Phenotypes were analyzed by flow cytometry, and cytokine levels were determined with cytometric bead array or ELISA.

RESULT

The percentage of CD11c(high)CD45RB(low) DCs was significantly increased after treatment with APS compared to their counterparts. The cytokine secretion pattern of CD11c(high)CD45RB(low) DCs and CD11c(low)CD45RB(high) DCs was detected, and it was found that unlike the stable IL-10 secretion pattern of CD11c(low)CD45RB(high) DCs induced by APS, CD11c(high)CD45RB(low) DCs showed a dose-dependent relationship between IL-12 production and APS stimulation. In order to verify whether the activation of CD4(+) T was associated with the differentiation of splenic DCs mediated by APS to CD11c(high)CD45RB(low) DCs, anti-IL-12 receptor (IL-12R) as well as anti-IL-10R monoclonal antibody was used to inhibit the effect of CD11c(high)CD45RB(low) DCs and CD11c(low)CD45RB(high) DCs in CD4(+) T mixed lymphocyte reaction culture. After treatment with anti-IL-12R or anti-IL-10 monoclonal antibody in CD4(+) T+CD11c(high)CD45RB(low) DCs or CD11c(low)CD45RB(high) DCs mixed lymphocyte reaction, the inductions of these DCs on T cells were inhibited dramatically.

CONCLUSION

APS might induce the differentiation of splenic DCs to CD11c(high)CD45RB(low) DCs followed by shifting of Th2 to Th1 with enhancement of T lymphocyte immune function in vitro. Also, the effect of APS on T-cell differentiation to Th1 was not associated with the inhibition of IL-10 production in CD11c(low)CD45RB(high) DCs.

Th17 cells can provide B cell help in autoantibody induced arthritis

K/BxN mice develop a spontaneous destructive arthritis driven by T cell dependent anti-glucose-6-phosphate isomerase (GPI) antibody production. In this study, a modified version of the K/BxN model, the KRN-cell transfer model (KRN-CTM), was established to determine the contribution of Th17 cells in the development of chronic arthritis. The transfer of naive KRN T cells into B6.TCR.Cα(-/-)H-2(b/g7) T cell deficient mice induced arthritis by day 10 of transfer. Arthritis progressively developed for a period of up to 14 days following T cell transfer, thereafter the disease severity declined, but did not resolve. Both IL-17A and IFNγ were detected in the recovered T cells from the popliteal lymph nodes and ankles. The transfer of KRN Th17 polarized KRN CD4(+) T cells expressing IL-17A and IFNγ induced arthritis in all B6.TCR.Cα(-/-)H-2(b/g7) mice however the transfer of Th1 polarized KRN CD4(+) T cells expressing IFNγ alone induced disease in only 2/3 of the mice and disease induction was delayed compared to Th17 transfers. Th17 polarized KRN/T-bet(-/-) cells induced arthritis in all mice and surprisingly, IFNγ was produced demonstrating that T-bet expression is not critical for arthritis induction, regardless of the cytokine expression. Neutralization of IFNγ in KRN Th17 transfers resulted in earlier onset of disease while the neutralization of IL-17A delayed disease development. Consistent with K/BxN mice, naive KRN T cell transfers and Th17 polarized KRN/T-bet(-/-) transfers induced anti-GPI IgG(1) dominant responses while KRN Th17 cells induced high levels of IgG(2b). These data demonstrate that Th17 cells can participate in the production of autoantibodies that can induce arthritis.

Characterization of the KRN cell transfer model of rheumatoid arthritis (KRN-CTM), a chronic yet synchronized version of the K/BxN mouse

In this study, a chronic yet synchronized version of the K/BxN mouse, the KRN-cell transfer model (KRN-CTM), was developed and extensively characterized. The transfer of purified splenic KRN T cells into T cell-deficient B6.TCR.Calpha(-/-)H-2(b/g7) mice induced anti-glucose 6-phosphate isomerase antibody-dependent chronic arthritis in 100% of the mice with uniform onset of disease 7 days after T cell transfer. Cellular infiltrations were assessed by whole-ankle transcript microarray, cytokine and chemokine levels, and microscopic and immunohistochemical analyses 7 through 42 days after T cell transfer. Transcripts identified an influx of monocytes/macrophages and neutrophils into the ankles and identified temporal progression of cartilage damage and bone resorption. In both serum and ankle tissue there was a significant elevation in interleukin-6, whereas macrophage inflammatory protein-1 alpha and monocyte chemotactic protein-1 were only elevated in tissue. Microscopic and immunohistochemical analyses revealed a time course for edema, synovial hypertrophy and hyperplasia, infiltration of F4/80-positive monocytes/macrophages and myeloperoxidase-positive neutrophils, destruction of articular cartilage, pannus invasion, bone resorption, extra-articular fibroplasia, and joint ankylosis. The KRN cell transfer model replicates many features of chronic rheumatoid arthritis in humans in a synchronized manner and lends itself to manipulation of adoptively transferred T cells and characterizing specific genes and T cell subsets responsible for rheumatoid arthritis pathogenesis and progression.

The dangerous liaison between iNKT cells and dendritic cells: does it prevent or promote autoimmune diseases?

Invariant natural killer T (iNKT) cells represent an important regulatory T-cell subset that perceives signals of danger and/or cellular distress and modulate the adaptive immune response accordingly. In the presence of pathogens, iNKT cells acquire an adjuvant function that is fundamental to boost anti-microbial and anti-tumor immunity. At the same time, iNKT cells can play a negative regulatory function to maintain peripheral T-cell tolerance toward self-antigens and to prevent autoimmune disease. Both these effects of iNKT cells involve the modulation of the activity of dendritic cells (DCs) through cell-cell interaction. Indeed, iNKT cells can either boost Th1 immunity by enhancing maturation of pro-inflammatory DCs or promote immune tolerance through the maturation of tolerogenic DCs. This dual action of iNKT cells opens questions on the modalities by which a single-cell subset can exert opposite effects on DCs and may even put in question the overall immunosuppressive properties of iNKT cells. This review presents the large body of evidence that shows the ability of iNKT cells to negatively regulate autoimmunity and to prevent autoimmune diseases including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, and systemic lupus erythematosus. In addition, an update is provided on the mechanisms of iNKT-DCs interactions and how this can result in inflammatory or tolerogenic responses.

Molecular targeting of islet autoantigens

Type 1 diabetes of man and animal models results from immune-mediated specific beta cell destruction. Multiple islet antigens are targets of autoimmunity and most of these are not beta cell specific. Immune responses to insulin appear to be essential for the development of diabetes of the NOD mouse. In this review, we will emphasize the unusual manner in which selected autoantigenic peptides (particularly the recently discovered target of BDC2.5 T cells [chromagranin A]) are presented and recognized by autoreactive CD4(+) T cell receptors. We hypothesize that "unusual" structural interactions of specific trimolecular complexes (MHC class II, peptide, and T cell receptors) are fundamental to the escape from the thymus of autoreactive T cells able to cause type 1 diabetes.

Transfusion of nonobese diabetic mice with allogeneic newborn blood ameliorates autoimmune diabetes and modifies the expression of selected immune response genes

Although allogeneic bone marrow transplantation has been shown to prevent autoimmune diabetes in heavily irradiated nonobese diabetic (NOD) mice, a similar procedure is not suitable for the treatment of patients with type 1 diabetes because of associated severe side effects. Therefore, we evaluated whether mouse newborn blood (NBB), equivalent to human umbilical cord blood, could be used for diabetes prevention without recipient preconditioning. To test this hypothesis, unconditioned, prediabetic female NOD mice were given a single injection of whole NBB derived from the allogeneic diabetes-resistant mouse strain C57BL/6. Transfusion of allogeneic NBB but not adult blood prevented diabetes incidence in a majority of treated mice for a prolonged period of time. This was accompanied by the release of insulin in response to a challenge with glucose. Invasive cellular infiltration of islets was also substantially reduced in these mice. Although NBB transfusion induced a low level of hematopoietic microchimerism, it did not strictly correlate with amelioration of diabetes. Induction of genes implicated in diabetes, such as Il18, Tnfa, and Inos but not Il4, Il17 or Ifng, was repressed in splenocytes derived from protected mice. Notably, expression of the transcription factor Tbet/Tbx21 but not Gata3 or Rorgt was upregulated in protected mice. These data indicate that allogeneic NBB transfusion can prevent diabetes in NOD mice associated with modulation of selected cytokine genes implicated in diabetes manifestation. The data presented in this study provide the proof of principle for the utility of allogeneic umbilical cord blood transfusion to treat patients with autoimmune diabetes.

Mouse Models for Type 1 Diabetes

Our understanding of the genetics, aetiology and pathogenesis of Type 1 Diabetes (T1D) was propelled by the discovery of animal models of T1D in the late 1970s and early 1980s, particularly the non-obese diabetic (NOD) mouse. Since then, transgenic and gene-targeting technologies allowed the generation of many models with reduced genetic and pathogenic complexity. These models allowed researchers to zoom in on specific aspects of this complex disease. In this review, we provide an overview of currently available mouse models for T1D.

Autoantibodies and associated T-cell responses to determinants within the 831-860 region of the autoantigen IA-2 in Type 1 diabetes

B-cells influence T-cell reactivity by facilitating antigen presentation, but the role of autoantibody-secreting B-cells in regulating T-cell responses in Type 1 diabetes is poorly defined. The aims of this study were to characterise epitopes on the IA-2 autoantigen for three monoclonal antibodies from diabetic patients by amino acid substitutions of selected residues of IA-2, establish contributions of these epitopes to binding of serum antibodies in Type 1 diabetes and relate B- and T-cell responses to overlapping determinants on IA-2. The monoclonal antibodies recognised overlapping epitopes, with residues within the 831-860 region of IA-2 contributing to binding; substitution of Glu836 inhibited binding of all three antibodies. Monoclonal antibody Fab fragments and substitution of residues within the 831-836 region blocked serum antibody binding to an IA-2 643-937 construct. IL-10-secreting T-cells responding to peptides within the 831-860 region were detected by cytokine-specific ELISPOT in diabetic patients and responses to 841-860 peptide were associated with antibodies to the region of IA-2 recognised by the monoclonal antibodies. The study identifies a region of IA-2 frequently recognised by antibodies in Type 1 diabetes and demonstrates that these responses are associated with T-cells secreting IL-10 in response to a neighbouring determinant.

Th17 cells promote pancreatic inflammation but only induce diabetes efficiently in lymphopenic hosts after conversion into Th1 cells

IDDM is characterized by leukocyte invasion to the pancreatic tissues followed by immune destruction of the islets. Despite the important function of Th17 cells in other autoimmune disease models, their function in IDDM is relatively unclear. In this study, we found association of elevated Th17 cytokine expression with diabetes in NOD mice. To understand the function of Th17 cells in IDDM, we differentiated islet-reactive BDC2.5 TcR transgenic CD4(+) cells in vitro into Th17 cells and transferred them into NOD.scid and neonate NOD mice. NOD.scid recipient mice developed rapid onset of diabetes with extensive insulitic lesions, whereas in newborn NOD mice, despite extensive insulitis, most recipient mice did not develop diabetes. Surprisingly, BDC2.5(+) cells recovered from diabetic NOD.scid mice, in comparison with those from neonate NOD mice, showed predominant IFN-gamma over IL-17 expression, indicating conversion of donor cells into Th1 cells. Moreover, diabetes progression in NOD.scid recipients was dependent on IFN-gamma while anti-IL-17 treatment reduced insulitic inflammation. These results indicate that islet-reactive Th17 cells promote pancreatic inflammation, but only induce IDDM upon conversion into IFN-gamma producers.

Dissociation of Experimental Allergic Encephalomyelitis Protective Effect and Allergic Side Reactions in Tolerization with Neuroantigen

Administration of autoantigens under conditions that induce type 2 immunity frequently leads to protection from T cell-mediated autoimmune diseases. Such treatments, however, are inherently linked to the induction of IgG1 Abs and to the risk of triggering anaphylactic reactions. We studied the therapeutic benefit vs risk of immune deviation in experimental allergic encephalomyelitis of SJL mice induced by MP4, a myelin basic protein-proteolipid protein (PLP) fusion protein. MP4 administration in IFA induced type 2 T cell immunity, IgG1 Abs, and experimental allergic encephalomyelitis protection, and all three were enhanced by repeat injections. Despite high Ab titers, anaphylactic side reactions were not observed when MP4 was repeatedly injected in IFA or as soluble Ag s.c. In contrast, lethal anaphylaxis was seen after s.c. injection of soluble PLP:139-151 peptide, but not when the peptide was reinjected in IFA. Therefore, the Ab response accompanying the immune therapy constituted an anaphylactic risk factor only when the autoantigen was not retained in an adjuvant and when it was small enough to be readily disseminated within the body. Taken together, our data show that treatment regimens can be designed to boost the protective type 2 T cell response while avoiding the risk of Ab-mediated allergic side effects.

Type II collagen without adjuvant induces eosinophilic arthritis

Eosinophilia is a characteristic feature of many inflammatory diseases including inflammatory bowel disease and asthma. It also occurs in a subtype of rheumatoid arthritis but the role of eosinophils has been unclear and animal models have been lacking. Here, we introduce a new mouse model to study the role of eosinophilia in arthritis. Intraperitoneal injection of type II collagen alone, without any adjuvant, was sufficient to induce chronic arthritis in a mouse with transgenic T cells specific for type II collagen. The arthritis was accompanied by infiltration of eosinophils into the synovial tissue and the disease could be blocked with neutralizing anti-IL-5 antibodies. To our knowledge, this is the first description of an eosinophilic disease form of destructive arthritis.

Animal models of spontaneous autoimmune disease: type 1 diabetes in the nonobese diabetic mouse

The nonobese diabetic (NOD) mouse represents probably the best spontaneous model for a human autoimmune disease. It has provided not only essential information on type 1 diabetes (T1D) pathogenesis, but also valuable insights into mechanisms of immunoregulation and tolerance. Importantly, it allows testing of immunointervention strategies potentially applicable to man. The fact that T1D incidence in the NOD mouse is sensitive to environmental conditions, and responds, sometimes dramatically, to immunomanipulation, does not represent a limit of the model, but is likely to render it even more similar to its human counterpart. In both cases, macrophages, dendritic cells, CD4+, CD8+, and B cells are present in the diseased islets. T1D is a polygenic disease, but, both in human and in NOD mouse T1D, the primary susceptibility gene is located within the MHC. On the other hand, T1D incidence is significantly higher in NOD females, although insulitis is similar in both sexes, whereas in humans, T1D occurs with about equal frequency in males and females. In addition, NOD mice have a more widespread autoimmune disorder, which is not the case in the majority of human T1D cases. Despite these differences, the NOD mouse remains the most representative model of human T1D, with similarities also in the putative target autoantigens, including glutamic acid decarboxylase IA-2, and insulin.

Fluorine-19 MRI for visualization and quantification of cell migration in a diabetes model

This article describes an in vivo imaging method for visualizing and quantifying a specific cell population. Cells are labeled ex vivo with a perfluoropolyether nanoparticle tracer agent and then detected in vivo using (19)F MRI following cell transfer. (19)F MRI selectively visualizes only the labeled cells with no background, and a conventional (1)H image taken in the same imaging session provides anatomical context. Using the nonobese diabetic mouse, an established model of type 1 diabetes, (19)F MRI data were acquired showing the early homing behavior of diabetogenic T cells to the pancreas. A computational algorithm provided T cell counts in the pancreas. Approximately 2% of the transferred cells homed to the pancreas after 48 hr. The technique allows for both unambiguous detection of labeled cells and quantification directly from the in vivo images. The in vivo quantification and cell trafficking patterns were verified using (19)F spectroscopy and fluorescence microscopy in excised pancreata. The labeling procedure did not affect T-cell migration in vivo. This imaging platform is applicable to many cell types and disease models and can potentially be used for monitoring the trafficking of cellular therapeutics.

NKT cells and IFN-gamma establish the regulatory environment for the control of diabetogenic T cells in the nonobese diabetic mouse

In type 1 diabetes mellitus (T1DM), T cell-mediated destruction of insulin-producing pancreatic beta cells leads to the acute onset of hyperglycemia. The nonobese diabetic mouse model of human T1DM reveals that T cells capable of inducing diabetes can escape normal central tolerance, and can cause T1DM if left unchecked. However, several regulatory T cell subsets can temper autoaggressive T cells, although it remains undetermined when and how, and by which subset, homeostatic control of diabetogenic T cells is normally achieved in vivo. Using a cotransfer model, we find that NKT cells efficiently dampen the action of diabetogenic CD4+ T cells, and do so in an indirect manner by modifying the host environment. Moreover, the NKT cell-containing population modifies the host via production of IFN-gamma that is necessary for driving the inhibition of diabetogenic T cells in vivo.

Antigen-based therapies using ignored determinants of beta cell antigens can more effectively inhibit late-stage autoimmune disease in diabetes-prone mice

As organ-specific autoimmune diseases do not become manifest until well-advanced, interventive therapies must inhibit late-stage disease processes. Using a panel of immunogenic peptides from various beta cell Ags, we evaluated the factors influencing the efficacy of Ag-based therapies in diabetes-prone NOD mice with advanced disease. The ability of the major beta cell autoantigen target determinants (TDs) to prime Th2 responses declined sharply between 6 and 12 wk of age, whereas the ability of immunogenic ignored determinants (IDs) of beta cell Ags to prime Th2 responses was unaffected by the disease process. The different patterns of TD and ID immunogenicity (even from the same beta cell Ag) may be due to the exhaustion of uncommitted TD-reactive, but not ID-reactive, T cell pools by recruitment into the autoimmune cascade. Therapeutic efficacy was associated with a peptide's immunogenicity and ability to promote Th2 spreading late in the disease process but not its affinity for I-Ag7 or its expression pattern (beta cell specific/nonspecific or rare/abundant). Characterization of some IDs revealed them to be "absolute" cryptic determinants. Such determinants have little impact on T cell selection, leaving large precursor T cell pools available for priming by synthetic peptides. Traditional Ag-based therapeutics using whole autoantigens or their TDs cannot prime responses to such determinants. These findings suggest a new strategy for designing more efficacious Ag-based therapeutics for late-stage autoimmune diseases.

A comprehensive review of interventions in the NOD mouse and implications for translation

Type 1 diabetes (T1D) animal models such as the nonobese diabetic (NOD) mouse have improved our understanding of disease pathophysiology, but many candidate therapeutics identified therein have failed to prevent/cure human disease. We have performed a comprehensive evaluation of disease-modifying agents tested in the NOD mouse based on treatment timing, duration, study length, and efficacy. Interestingly, some popular tenets regarding NOD interventions were not confirmed: all treatments do not prevent disease, treatment dose and timing strongly influence efficacy, and several therapies have successfully treated overtly diabetic mice. The analysis provides a unique perspective on NOD interventions and suggests that the response of this model to therapeutic interventions can be a useful predictor of the human response as long as careful consideration is given to treatment dose, timing, and protocols; more thorough investigation of these parameters should improve clinical translation.

Dietary (n-3) polyunsaturated fatty acids modulate murine Th1/Th2 balance toward the Th2 pole by suppression of Th1 development

We showed that dietary long-chain (n-3) PUFAs present in fish oil (FO) affect CD4(+) T cell proliferation and cytokine production in C57BL/6 mice. To test the hypothesis that the anti-inflammatory effect of dietary (n-3) PUFAs could be due to the indirect suppression of T helper (Th)1 cells by cross-regulation of enhanced Th2 activation, mice were fed a wash-out control diet [5% corn oil (CO), (n-6) PUFA] for 1 wk, followed by the control diet or a fish oil diet [1% CO + 4% FO, (n-3) PUFA] for 2 wk. Splenic CD4+ T cells were cultured under both neutral and Th2 polarizing conditions for 2 d. Cells were reactivated and analyzed for interleukin-4 and interferon-gamma by intracellular cytokine staining. Dietary fish oil significantly increased the percentage of Th2 polarized cells and suppressed Th1 cell frequency under neutral conditions. However, under Th2 polarizing conditions, although the suppression of Th1 cells was maintained in FO-fed mice, no effect was observed in Th2 cells. Dietary fish oil increased the Th2/Th1 ratio in the presence of homologous mouse serum under both neutral (P = 0.0009) and Th2 polarizing conditions (P = 0.0185). The FO diet did not significantly affect proliferation under Th2 polarizing conditions. Thus, the anti-inflammatory effects of FO may be explained in part by a shift in the Th1/Th2 balance, due to the direct suppression of Th1 development, and not by enhancement of the propensity of CD4+ T cells to be polarized toward a Th2 phenotype, at least in vitro.

The NOD mouse: a model of immune dysregulation

Autoimmunity is a complex process that likely results from the summation of multiple defective tolerance mechanisms. The NOD mouse strain is an excellent model of autoimmune disease and an important tool for dissecting tolerance mechanisms. The strength of this mouse strain is that it develops spontaneous autoimmune diabetes, which shares many similarities to autoimmune or type 1a diabetes (T1D) in human subjects, including the presence of pancreas-specific autoantibodies, autoreactive CD4+ and CD8+ T cells, and genetic linkage to disease syntenic to that found in humans. During the past ten years, investigators have used a wide variety of tools to study these mice, including immunological reagents and transgenic and knockout strains; these tools have tremendously enhanced the study of the fundamental disease mechanisms. In addition, investigators have recently developed a number of therapeutic interventions in this animal model that have now been translated into human therapies. In this review, we summarize many of the important features of disease development and progression in the NOD strain, emphasizing the role of central and peripheral tolerance mechanisms that affect diabetes in these mice. The information gained from this highly relevant model of human disease will lead to potential therapies that may alter the development of the disease and its progression in patients with T1D.

Transgenic Ly-49A inhibits antigen-driven T cell activation and delays diabetes

Activation of islet-specific T cells plays a significant role in the development of type 1 diabetes. In an effort to control T cell activation, we expressed the inhibitory receptor, Ly-49A, on islet-specific mouse CD4 cells. Ag-mediated activation of Ly-49A T cells was inhibited in vitro when the Ly-49A ligand, H-2D(d), was present on APCs. Ag-driven T cell proliferation, cytokine production, and changes in surface receptor expression were significantly reduced. Inhibition was also evident during secondary antigenic challenge. Addition of exogenous IL-2 did not rescue cells from inhibition, suggesting that Ly-49A engagement does not lead to T cell anergy. Importantly, in an adoptive transfer model, Ly-49A significantly delays the onset of diabetes. Together these results demonstrate that the inhibitory receptor Ly-49A effectively limits Ag-specific CD4 cell responses even in the presence of sustained autoantigen expression in vivo.

A concept on the role of Helicobacter pylori infection in autoimmune pancreatitis

Autoimmune pancreatitis, an inflammatory process of the pancreas due to an autoimmune mechanism establishing etiology of chronic pancreatitis, is characterized by the presence of autoantibodies, hypergammaglobulinemia, pancreatic enlargement, pancreatic duct strictures, and pathologic features of fibrotic changes with intense, mainly lymphocytic infiltrations, which may contribute to tissue destruction probably by apoptosis. In almost 60% of the cases, this type of pancreatitis coexists with other autoimmune diseases such as Sjogren's syndrome, sclerosing extrahepatic cholangitis, primary biliary cirrhosis, autoimmune hepatitis, or other extrapancreatic disorders, and recently with gastric peptic ulceration. The diversity of extrapancreatic lesions with similar histopathologic findings suggests general involvement of the digestive system in this disease, although the presence of such involvement has not been fully elucidated. Similarly, Helicobacter pylori (H. pylori) infection, a well known cause of gastric ulcer, has been associated, via molecular mimicry of host structures by its constituents with the same autoimmune conditions, also characterized by fibrotic changes and/or lymphoplasmacytic inflammations, accompanied by aberrations of T cell apoptosis that contribute to hepatobiliary- or extrahepatic-tissue destruction. Considering that H. pylori is involved in the pathogenesis and pathophysiology of these autoimmune disorders, we propose that this organism might trigger autoimmune pancreatitis through induction of autoimmunity and apoptosis.

A concept on the role of Helicobacter pylori infection in autoimmune pancreatitis

Autoimmune pancreatitis, an inflammatory process of the pancreas due to an autoimmune mechanism establishing etiology of chronic pancreatitis, is characterized by the presence of autoantibodies, hypergammaglobulinemia, pancreatic enlargement, pancreatic duct strictures, and pathologic features of fibrotic changes with intense, mainly lymphocytic infiltrations, which may contribute to tissue destruction probably by apoptosis. In almost 60% of the cases, this type of pancreatitis coexists with other autoimmune diseases such as Sjogren's syndrome, sclerosing extrahepatic cholangitis, primary biliary cirrhosis, autoimmune hepatitis, or other extrapancreatic disorders, and recently with gastric peptic ulceration. The diversity of extrapancreatic lesions with similar histopathologic findings suggests general involvement of the digestive system in this disease, although the presence of such involvement has not been fully elucidated. Similarly, Helicobacter pylori (H. pylori) infection, a well known cause of gastric ulcer, has been associated, via molecular mimicry of host structures by its constituents with the same autoimmune conditions, also characterized by fibrotic changes and/or lymphoplasmacytic inflammations, accompanied by aberrations of T cell apoptosis that contribute to hepatobiliary- or extrahepatic-tissue destruction. Considering that H. pylori is involved in the pathogenesis and pathophysiology of these autoimmune disorders, we propose that this organism might trigger autoimmune pancreatitis through induction of autoimmunity and apoptosis.

A concept on the role of Helicobacter pylori infection in autoimmune pancreatitis

Autoimmune pancreatitis, an inflammatory process of the pancreas due to an autoimmune mechanism establishing etiology of chronic pancreatitis, is characterized by the presence of autoantibodies, hypergammaglobulinemia, pancreatic enlargement, pancreatic duct strictures, and pathologic features of fibrotic changes with intense, mainly lymphocytic infiltrations, which may contribute to tissue destruction probably by apoptosis. In almost 60% of the cases, this type of pancreatitis coexists with other autoimmune diseases such as Sjogren's syndrome, sclerosing extrahepatic cholangitis, primary biliary cirrhosis, autoimmune hepatitis, or other extrapancreatic disorders, and recently with gastric peptic ulceration. The diversity of extrapancreatic lesions with similar histopathologic findings suggests general involvement of the digestive system in this disease, although the presence of such involvement has not been fully elucidated. Similarly, Helicobacter pylori (H. pylori) infection, a well known cause of gastric ulcer, has been associated, via molecular mimicry of host structures by its constituents with the same autoimmune conditions, also characterized by fibrotic changes and/or lymphoplasmacytic inflammations, accompanied by aberrations of T cell apoptosis that contribute to hepatobiliary- or extrahepatic-tissue destruction. Considering that H. pylori is involved in the pathogenesis and pathophysiology of these autoimmune disorders, we propose that this organism might trigger autoimmune pancreatitis through induction of autoimmunity and apoptosis.

Prior Bordetella pertussis infection modulates allergen priming and the severity of airway pathology in a murine model of allergic asthma

BACKGROUND

It has been proposed that T helper (Th)2-driven immune deviation in early life can be countered by Th1 inducing childhood infections and that such counter-regulation can protect against allergic asthma.

OBJECTIVE

To test whether Th1-inducing infection with Bordetella pertussis protects against allergic asthma using well-characterized murine models.

METHODS

Groups of mice were sensitized to ovalbumin (OVA) in the presence or absence of B. pertussis, a well-characterized Th1 inducing respiratory infection. Immunological, pathological and physiological parameters were measured to assess the impact of infection on immune deviation and airway function.

RESULTS

We demonstrate that OVA sensitization does not affect the development of B. pertussis-specific immune responses dominated by IgG2a and IFN-gamma and does not impair Th1-mediated clearance of airway infection. In contrast, B. pertussis infection at the time of sensitization modulated the response to OVA and significantly reduced total serum and OVA-specific IgE. The pattern of cytokine responses, in particular OVA-specific IL-5 responses in the spleen was also modulated. However, B. pertussis did not cause global suppression as IL-10 and IL-13 levels were enhanced in OVA-stimulated spleen cell cultures and in lavage fluid from infected co-sensitized mice. Histopathological examination revealed that B. pertussis infection prior to OVA sensitization resulted in increased inflammation of bronchiolar walls with accompanying hyperplasia and mucous metaplasia of lining epithelia. These pathological changes were accompanied by increased bronchial hyper-reactivity to methacholine exposure.

CONCLUSION

Contrary to the above premise, a Th1 response induced by a common childhood infection does not protect against bronchial hyper-reactivity, but rather exacerbates the allergic asthmatic response, despite modulation of immune mediators.

Intracellular IFN-gamma production and IL-12 serum levels in latent autoimmune diabetes of adults (LADA) and in type 2 diabetes

Th1 cytokines, such as interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), and Th1-inducing cytokines, such as IL-12, are involved in the pathogenesis of various organ-specific autoimmune diseases, including autoimmune diabetes. In this study, we investigated intracellular IFN-gamma release by T lymphocytes and IL-12 serum levels in 48 type 2 and 36 latent autoimmune diabetes of adults (LADA) diabetics and 25 control subjects in an attempt to evaluate their role in the pathogenesis of these clinical entities. Ionomycin (ION) and phorbol-12-myristate-13-acetate (PMA)-activated peripheral blood mononuclear cells (PBMCs) were stained with anti-CD4-FITC or anti-CD8-FITC and anti-IFN-gamma phycoerythrin (PE) monoclonal antibodies (mAbs) and analyzed by flow cytometry. IL-12 serum levels were determined by enzyme-linked immunosorbent assay (ELISA). In all study groups, IFN-gamma content of CD4(+) and CD8(+) lymphocytes was significantly upregulated by stimulation. Furthermore, it was observed that CD4(+) and CD8(+) lymphocytes from type 2 diabetics produced significantly lower levels of IFN-gamma compared with LADA patients and controls. However, the percentages of CD4(+)/IFN-gamma(+) and CD8(+)/IFN-gamma(+) cells from type 2 diabetics were significantly higher compared with controls. The flow cytometric picture of intracellular IFN-gamma release in LADA patients did not differ from that observed in controls. However, IL-12 serum levels in type 2 and LADA diabetics were lower than in controls. Because Th1 cytokines have been associated with the pathogenesis of autoimmune diabetes, these results preclude Th1 involvement in the autoimmune phenomena observed in LADA patients. In contrast, the low IFN-gamma levels observed in type 2 diabetics in combination with the low IL-12 serum levels might be a contributing factor in the frequently observed chronic complications in these patients.

Converting relapsing remitting to secondary progressive experimental allergic encephalomyelitis (EAE) by ultraviolet B irradiation

We induced experimental allergic encephalomyelitis (EAE) in SJL/J mice, an animal model for multiple sclerosis (MS), using myelin oligodendrocyte glycoprotein (MOG)(92-106) peptide, following ultraviolet (UV) irradiation. While all control mice developed relapsing-remitting (RR)-EAE, UV irradiation induced secondary progressive (SP)-EAE in some of the mice. Although mild demyelination was observed with T cell infiltration in RR-EAE, large demyelinating lesions developed in SP-EAE with massive macrophage and neutrophil infiltration and immunoglobulin deposition, but with little T cell infiltration. UV irradiation induced higher anti-MOG antibody responses. In SP-EAE, lymphoproliferative responses and interferon-gamma production were decreased without alteration of interleukin-4.

E2f1 mutation induces early onset of diabetes and Sjögren's syndrome in nonobese diabetic mice

E2f1 is an important regulator of T cell proliferation, differentiation, and apoptosis that controls the transcription of a group of genes that are normally regulated at the G1 to S phase transition in the cell cycle. Insulin-dependent diabetes mellitus (IDDM) and Sjogren's syndrome (SS) are highly regulated autoimmune diseases that develop spontaneously in NOD mice. The aim of the present in vivo study was to explore the functional importance of the E2f1 molecule in IDDM and SS, in the context of whole animal physiology and pathophysiology, using E2f1-deficient NOD mice. For the experiment, we produced NOD mice homozygous for a nonfunctional E2f1 allele onto a NOD background. E2f1-deficient NOD mice developed an early and increased onset of diabetes as compared with their littermates. These mice also exhibited a defect in T lymphocyte development, leading to excessive numbers of mature T cells (CD4+ and CD8+), due to a maturation stage-specific defect in the apoptosis of thymocytes and peripheral T cells. We also found that they also exhibited a more rapid and increased entry into the S phase following antigenic stimulation of spleen cells and thymocytes in vitro. Furthermore, E2f1-deficient mice showed a profound decrease of immunoregulatory CD4+CD25+ T cells, while the spleen cells of NOD mice lacking E2f1 showed a significant increase of the proinflammatory cytokine IFN-gamma following antigenic stimulation in vitro. Consistent with these observations, E2f1 homozygous mutant NOD mice were highly predisposed to the development of IDDM and SS.

IL-10-producing and naturally occurring CD4+ Tregs: limiting collateral damage

Effective immune responses against pathogens are sometimes accompanied by strong inflammatory reactions. To minimize damage to self, the activation of the immune system also triggers anti-inflammatory circuits. Both inflammatory and anti-inflammatory reactions are normal components of the same immune response, which coordinately fight infections while preventing immune pathology. IL-10 is an important suppressive cytokine, produced by a large number of immune cells in addition to the antigen-driven IL-10-producing regulatory and the naturally occurring suppressor CD4+ T cells, which is a key player in anti-inflammatory immune responses. However, additional mechanisms have evolved to ensure that pathogen eradication is achieved with minimum damage to the host. Here we discuss those mechanisms that operate to regulate effector immune responses.

Therapeutic manipulation of T cell chemotaxis in transplantation

T cell migration and trafficking are regulated by the well defined cellular processes of rolling, activation, tight adhesion, arrest and diapedesis. These processes are, in turn, controlled by molecular events involving integrins, selectins, chemokines and chemokine receptors. Recent studies have shown that sphingosine 1-phosphate receptors and their ligands are also important molecular modulators of migration and trafficking. Many of these molecules are appropriate targets for preventing allograft rejection or for achieving tolerance. Studies of migration and trafficking have also shown that the anatomic choreography of alloantigen presentation and T cell encounter with alloantigen and immunosuppression, are over-riding determinants of T cell priming versus tolerization.

DNA vaccination encoding glutamic acid decarboxylase can enhance insulitis and diabetes in correlation with a specific Th2/3 CD4 T cell response in non-obese diabetic mice

DNA vaccination encoding beta cell autoantigens has been shown very recently to prevent type I diabetes in non-obese diabetic (NOD) mice. However, DNA vaccination encoding microbial or reporter antigens is known to induce specific long-lasting CD4 Th1 and strong cytolytic CD8 T cell responses. As this immune phenotype is associated strongly with beta cell destruction leading to diabetes, we have chosen to study the effects of plasmids encoding glutamic acid decarboxylase (GAD), a crucial beta cell autoantigen, in female NOD mice that developed a 'moderate' diabetes incidence. In the present study, 3-week-old female NOD mice were vaccinated twice in tibialis muscles with plasmid-DNA encoding 65-kDa GAD or betagalactosidase. In GAD-DNA immunized mice, diabetes cumulative incidence (P < 3.10(-3)) and insulitis (P < 7.10(-3)) increased significantly. Simultaneously, DNA immunization induced GAD-specific CD4 T cells secreting interleukin (IL)-4 (P < 0.05) and transforming growth factor (TGF)-beta (P = 0.03). These cells were detected in spleen and in pancreatic lymph nodes. Furthermore, vaccination produced high amounts of Th2 cytokine-related IgG1 (P < 3.10(-3)) and TGF-beta-related IgG2b to GAD (P = 0.015). Surprisingly, diabetes onset was correlated positively with Th2-related GAD-specific IgG1 (P < 10(-4)) and TGF-beta-related IgG2b (P < 3.10(-3)). Moreover, pancreatic lesions resembled Th2-related allergic inflammation. These results indicate, for the first time, that GAD-DNA vaccination could increase insulitis and diabetes in NOD mice. In addition, our study suggests that Th2/3 cells may have potentiated beta cell injury.