Both Il2−/− mice and Scurfy (Sf) mutant mice that are deficient in FoxP3, develop multi-organ inflammation but only the latter display severe skin and lung inflammation. In contrast, Sf.Il2−/− double mutant mice do not display skin inflammation and markedly reduced lung inflammation. In this review, we summarize our recent findings based on microarray, q-PCR and functional studies of 10 Sf double mutant mice. These studies revealed novel pro-inflammatory functions of IL-2 in regulating inflammation in an organ-specific manner. IL-2 exerts its “organ-specific” pro-inflammatory function by regulating the migration and retention of CD4+ T-cells (both Th1 and Th2) specifically to the skin and lung. In addition, IL-2 is also required for regulating the Th2 cytokine response during T-cell activation. Further studies on these IL-2 –regulated genes will help in identifying novel targets for intervention in inflammatory diseases of skin and lung.
Treg; Scurfy mice; autoimmune diseases; inflammation
Immunosuppression resulting from excessive post-trauma apoptosis of hyperactivated Tcells is controversial. TRAIL mediated Tcell apoptosis decreases highly activated Tcells’ responses. Caspase-10, a particular TRAIL target, was increased in trauma patients’ Tcells with concomitantly elevated plasma TRAIL levels. These patients’ Tcells developed anergy, implicating increased TRAIL-mediated Tcell apoptosis in post-trauma Tcell anergy. Control Tcells cultured with patients’ sera containing high TRAIL levels increased their Caspase-10 activity and apoptosis. Stimulated primary Tcells are TRAIL apoptosis resistant. Increased plasma Thrombospondin-1 and Tcell expression of CD47, a Thrombospondin-1 receptor, preceded patients’ Tcell anergy. CD47 triggering of Tcells increased their sensitivity to TRAIL-induced apoptosis. Augmentation of Tcell TRAIL-induced apoptosis was secondary to CD47 triggered activation of the Src homology-containing phosphatase-1(SHP-1) and was partially blocked by a SHP-1 inhibitor. We suggest that combined post-trauma CD47 triggering, SHP-1 mediated NFκB suppression, and elevated TRAIL levels increase patients’ CD47 expressing Tcell apoptosis, thus contributing to subsequent Tcell anergy.
Human T cells; Trauma; TRAIL; Apoptosis; CD47
The activation of immune cells is mediated by a network of signaling proteins that can undergo post-translational modifications critical for their activity. Methylation of nucleic acids or proteins can have major effects on gene expression as well as protein repertoire diversity and function. Emerging data indicate that indeed many immunologic functions, particularly those of T cells, including thymic education, differentiation and effector function are highly dependent on methylation events. The critical role of methylation in immunocyte biology is further documented by evidence that autoimmune phenomena may be curtailed by methylation inhibitors. Additionally, epigenetic alterations imprinted by methylation can also exert effects on normal and abnormal immune responses. Further work in defining methylation effects in the immune system is likely to lead to a more detailed understanding of the immune system and may point to the development of novel therapeutic approaches.
Autoimmunity; Transmethylation; T cells; Lupus; EAE
Abnormal T-cell signaling and activation is a characteristic feature in systemic lupus erythematosus (SLE). Lupus T cells are shifted towards an over-activated state, important signaling pathways are rewired, and signaling molecules are replaced. Disturbances in metabolic and organelle homeostasis, importantly within the mitochondrial, endosomal, and autophagosomal compartments, underlie the changes in signal transduction. Mitochondrial hyperpolarization, enhanced endosomal recycling, and dysregulated autophagy are hallmarks of pathologic organelle homeostasis in SLE. This review is focused on the metabolic checkpoints of endosomal traffic that control immunological synapse formation and mitophagy and may thus serve as targets for treatment in SLE.
Systemic lupus erythematosus; T cell; mitochondria; endocytic recycling; mammalian target of rapamycin; autophagy
Osteoarthritis; Calcium crystals; Syk; PI3 kinase
The availability of both HLA data and genotypes for thousands of SNPs across the major histocompatibility complex (MHC) in 1240 complete families of the Type 1 Diabetes Genetics Consortium allowed us to analyze the occurrence and extent of megabase contiguous identity for founder chromosomes from unrelated individuals. We identified 82 HLA-defined haplotype groups, and within these groups, megabase regions of SNP identity were readily apparent. The conserved chromosomes within the 82 haplotype groups comprise approximately one third of the founder chromosomes. It is currently unknown whether such frequent conservation for groups of unrelated individuals is specific to the MHC, or if initial binning by highly polymorphic HLA alleles facilitated detection of a more general phenomenon within the MHC. Such common identity, specifically across the MHC, impacts type 1 diabetes susceptibility and may impact transplantation between unrelated individuals.
Type 1 diabetes; MHC; HLA; Extended haplotypes; SNP; 8.1; DR8
Systemic lupus erythematosus (SLE) is a disease that disproportionately affects females. Despite significant research effort, the mechanisms underlying the female predominance in this disease are largely unknown. Previously, we showed that estrogen receptor alpha knockout (ERαKO) lupus prone female mice had significantly less pathologic renal disease and proteinuria, and significantly prolonged survival. Since autoantibody levels and number and percentage of B/T cells were not significantly impacted by ERα genotype, we hypothesized that the primary benefit of ERα deficiency in lupus nephritis was via modulation of the innate immune response. Using BMDCs and spleen cells/B cells from female wild-type or ERαKO mice, we found that ERαKO-derived cells have a significantly reduced inflammatory response after stimulation with TLR agonists. Our results indicate that the inflammatory response to TLR ligands is significantly impacted by the presence of ERα despite the absence of estradiol, and may partially explain the protective effect of ERα deficiency in lupus-prone animals.
Estrogen receptor alpha; Systemic lupus; erythematosus; Dendritic cells; Toll-like receptors
We have previously reported that TRAIL is upregulated on T cells from patients with lupus and that T-cell associated TRAIL enhances autoimmune parameters in a murine model of lupus. Whether TRAIL/TRAIL-R interaction plays a role in organ involvement such as lupus nephritis has not yet been asssessed. We demonstrate here that TRAIL, DR4 and DR5 are upregulated in proximal and distal tubules of patients with proliferative lupus nephritis. In vitro, expression of TRAIL, DR4 and DR5 on primary proximal tubular epithelial cells (PTEC) was induced by TNFα and IFNγ. Functionally, TRAIL did not induce apoptosis but rather enhanced the proliferation of PTEC through activation of PI3 kinase/AKT and ERK1/2, increased IL-8 production and upregulated ICAM-1 expression. These data demonstrate that cytokine induced upregulation of TRAIL, DR4 and DR5 in tubules from patients with proliferative lupus nephritis may play a protective role by enhancing PTEC survival while also exerting a proinflammatory effect that may contribute to local inflammation and injury.
Autoimmunity; Systemic lupus erythematosus; Lupus nephritis; TNF related apoptosis inducing ligand; Apoptosis
Multiple sclerosis (MS) is a neurodegenerative disease in which the immune system recognizes proteins of the myelin sheath as antigenic, thus initiating an inflammatory reaction in the central nervous system. This leads to demyelination of the axons, breakdown of the blood-brain barrier, and lesion formation. Current therapies for the treatment of MS are generally non-specific and weaken the global immune system, thus making the individual susceptible to opportunistic infections. Antigenic peptides and their derivatives are becoming more prevalent for investigation as therapeutic agents for MS because they possess immune-specific characteristics. In addition, other peptides that target vital components of the inflammatory immune response have also been developed. Therefore, the objectives of this review are to (a) summarize the immunological basis for the development of MS, (b) discuss specific and non-specific peptides tested in EAE and in humans, and (c) briefly address some problems and potential solutions with these novel therapies.
Multiple Sclerosis; Experimental Autoimmune Encephalomyelitis; Peptide; Antigen; Bifunctional Peptide Inhibitor
In this study we examine the effects of aging on antigen presentation of B cells and monocytes. We compared the antigen presentation function of peripheral blood B cells from young and old subjects using a system that specifically measures the B cell receptor (BCR)-mediated MHC-II antigen presentation. Monocytes were studied as well. Overall the mean magnitude of antigen presentation of soluble antigen and peptide was not different in older and younger subjects for both B cells and monocytes. Older subjects, however, showed increased heterogeneity of BCR-mediated antigen presentation by their B cells. The magnitude and variability of peptide presentation, which does not require uptake and processing, was the same between groups. Presentation by monocytes had similar variability between the older and younger subjects. These data suggest that poor B cell antigen processing, which results in diminished presentation in some older individuals may contribute to poor vaccine responses.
antigen presentation; antigen processing; geriatrics; B cells; monocytes; immunosenescence
The humoral innate immune response consists of multiple components, including the naturally occurring antibodies (NAb), pentraxins and the complement and contact cascades. As soluble, plasma components, these innate proteins provide key elements in the prevention and control of disease. However, pathogens and cells with altered self proteins utilize multiple humoral components to evade destruction and promote pathogy. Many studies have examined the relationship between humoral immunity and autoimmune disorders. This review focuses on the interactions between the humoral components and their role in promoting the pathogenesis of bacterial and viral infections and chronic diseases such as atherosclerosis and cancer. Understanding the beneficial and detrimental aspects of the individual components and the interactions between proteins which regulate the innate and adaptive response will provide therapeutic targets for subsequent studies.
Complement; Contact cascade; Pentraxins; Natural antibodies; Cancer; Infection
Anti-CD3 mAb is an effective therapy that can reverse diabetes in NOD mice and has therapeutic potential in patients with type 1 diabetes (T1D). We administered anti-CD3 to PDL1−/−.NOD mice in order to determine whether this treatment would reverse the development of diabetes in these mice. Mice injected with anti-CD3 neonatally were protected from T1D. However, all of these anti-CD3 treated PDL1−/−.NOD mice developed a wasting disease between 12–20 weeks of age with sudden deterioration and weight loss, leading to death within 3–5 days of development of illness. Histology revealed severe inflammation in the heart and skeletal muscles. These results suggest that deficiency of PDL1 in NOD background has the potential to lead to immune-mediated tissue damage in organs other than the pancreas, but this cannot be appreciated in PDL1−/−.NOD mice as the mice develop T1D at an early age and die from diabetes prior to manifesting other autoimmune diseases.
A subset of patients with relapsing-remitting multiple sclerosis (RRMS) on therapy with interferon beta (IFNβ) develop neutralising anti-drug antibodies (ADA) resulting in reduced, or loss of, therapeutic efficacy. The aims were to characterise the relative contributions of anti-IFNβ antibody isotypes to drug neutralising activity, ability of these antibodies to cross-react with endogenous IFNβ, to form immune complexes and activate complement. IFNβ-specific ADA were measured in plasma from RRMS patients treated with IFNβ1a (Rebif®). Neutralisation of endogenous and therapeutic IFNβ by ADA was determined by IFNβ bioassay. IFNβ-ADA profile was predominantly comprised of IgG1 and IgG4 antibody isotypes. The contribution of IgG4-ADA towards neutralising activity was found to be minimal. Neutralising IFNβ-ADA blocks endogenous IFNβ activity. ADA interaction with therapeutic IFNβ results in immune complex formation and complement activation. In summary, IgG1 and IgG4 IFNβ-ADA have the ability to neutralise therapeutic and endogenous protein and to activate complement.
•IgG4 and IgG1 contributes to IFNβ-ADA profile•Neutralising IFNβ-ADA cross reacts and blocks endogenous IFNβ activity.•ADA-IFNβ results in IC formation and complement activation
Interferon beta;; Relapsing-remitting multiple sclerosis;; Immunogenicity;; Anti-drug antibody;; Neutralising antibody;; Complement
The common CCR5 promoter polymorphism at position –2459 (A/G) has been associated with differences in the rate of progression to AIDS, where HIV-1-infected individuals with the CCR5 –2459 G/G genotype exhibit slower disease progression than those with the A/A genotype. Mechanisms underlying the relationship between these polymorphisms and disease progression are not known. Here through in vitro infection of peripheral blood mononuclear cells obtained from healthy Caucasian blood donors with macrophage-tropic HIV-1 isolates we observed low, medium, and high viral propagation in association with G/G, A/G, and A/A promoter genotypes, respectively. Flow cytometric analysis of unstimulated CD14+ monocytes from these same donors revealed a similar hierarchy of CCR5 receptor density in association with promoter genotypes. Finally, PBMC from persons with the G/G promoter polymorphism produced higher levels of β-chemokines after in vitro stimulation. Thus, the CCR5 –2459 (A/G) promoter polymorphism determines CCR5 expression and predicts the magnitude of HIV-1 propagation in vitro. These findings may provide important insight regarding the regulation of mechanisms that influence the rate of HIV-1 propagation and progression to AIDS.
DNA is a polymeric macromolecule whose biological activities depend on location as well as binding to associated molecules. Inside the cell, DNA is the source of genetic information and binds histones to form nucleosomes. DNA can exit the cell, however, to enter the extracellular space primarily during cell death, either apoptosis or necrosis, as well as NETosis. While bacterial DNA is a potent immune stimulant by virtue of its CpG motifs, mammalian DNA, which is ordinarily inactive, can acquire activity by associating with nuclear, cytoplasmic and serum proteins which promote its uptake into cells to stimulate internal DNA sensors, including toll-like receptor 9. Among these proteins, anti-DNA autoantibodies can form immune complexes with DNA to stimulate plasmacytoid dendritic cells to produce type 1 interferon. Together, these findings suggest that the immune properties of DNA are mutable and diverse, reflecting its context and the array of attached molecules.
DNA; anti-DNA; systemic lupus erythematosus; apoptosis; immune complexes; HMGB1
Youth infected with HIV at birth often have sleep disturbances, neurocognitive deficits, and abnormal psychosocial function which are associated with and possibly resulted from elevated blood cytokine levels that may lead to a decreased quality of life. To identify molecular pathways that might be associated with these disorders, we evaluated 38 HIV-infected and 35 uninfected subjects over 18-months for intracellular cytokine levels, sleep patterns and duration of sleep, and neurodevelopmental abilities. HIV infection was significantly associated with alterations of intracellular pro-inflammatory cytokines (TNF-α, IFN-γ, IL-12), sleep factors (total time asleep and daytime sleep patterns), and neurocognitive factors (parent and patient reported problems with socio-emotional, behavioral, and executive functions; working memory-mental fatigue; verbal memory; and sustained concentration and vigilance. By better defining the relationships between HIV infection, sleep disturbances, and poor psychosocial behavior and neurocognition, it may be possible to provide targeted pharmacologic and procedural interventions to improve these debilitating conditions.
pediatric HIV infection; intracellular cytokines; sleep behavior; neurodevelopment; neurocognition; path analysis
Current therapies for systemic lupus erythematosus (SLE), a debilitating, potentially lethal, multifactorial systemic autoimmune disease, are limited to suppressing disease activity and are associated with multiple adverse effects. Recent advances in basic and translational sciences have elucidated a crucial role for the interferon-alpha (IFNα) pathway in the pathogenesis of this enigmatic disease. The so-called “type I interferon signature” has emerged as a major risk factor for disease activity of SLE. Multiple genes encoding for molecules within the type I interferon pathway have been associated with SLE in genome wide association studies. In addition, innate immune receptors are thought to be triggered by either endogenous and/or exogenous stimuli that lead to hypersecretion of IFNα. We review the multiple emerging treatment strategies targeting IFNα-related pathways. These include monoclonal antibodies against IFNα, anti-IFNα antibody-inducing vaccines, and inhibitors of toll-like receptors. We also summarize the current status of these pharmaceutical agents in early clinical trials.
pDC; TLR; IRF; JAK/STAT; Pin1; interferonopathies; virome; proteasome
Asthma is an inflammatory disorder of the airways, characterized by infiltration of mast cells, eosinophils, and Th2-type CD4+ T cells in the airway wall. Airway epithelium constitutes the first line of interaction with our atmospheric environment. The protective barrier function of the airway epithelium is likely impaired in asthma. Furthermore, recent studies suggest critical immunogenic and immunomodulatory functions of airway epithelium. In particular, a triad of cytokines, including IL-25, IL-33 and TSLP, is produced and released by airway epithelial cells in response to various environmental and microbial stimuli or by cellular damage. These cytokines induce and promote Th2-type airway inflammation and cause remodeling and pathological changes in the airway walls, suggesting their pivotal roles in the pathophysiology of asthma. Thus, the airway epithelium can no longer be regarded as a mere structural barrier, but must be considered an active player in pathogenesis of asthma and other allergic disorders.
asthma; epithelium; IL-25; IL-33; TSLP
Program Death-1 (PD-1) has been documented to negatively regulate immune responses. However, the cellular and molecular mechanisms for PD-1-mediated immune suppression have not been fully elucidated. In this study, we show that loss of PD-1 does not lead to defective induction of CD4+ T cell anergy in vitro and in vivo. Rather, the absence of PD-1 inhibits the development of inducible CD4+Foxp3+ regulatory T cells (iTregs) induced by TGF-β in vitro. In support of this finding, PD-1 deficiency impairs the generation of iTregs in vivo and leads to development of severe T cell-transfer-induced colitis. Mechanistically, defective iTreg generation in the absence of PD-1 was attributed to the heightened phosphorylation of Akt. Therefore, we first demonstrate that PD-1 controls peripheral T cell tolerance via an anergy-independent but iTreg-dependent mechanism.
costimulation; tolerance/suppression/anergy; T cell
To reduce connective tissue IL-6 level stimulated by LPS, it is essential to control IL-6 expression in both mononuclear cells and fibroblasts. However, it is unclear whether the regulatory mechanisms for both cells are similar or not. In this study, we found that signaling pathways mediating LPS-stimulated IL-6 in mononuclear U937 cells and fibroblasts were different. Furthermore, our studies showed that while LPS activated AP-1 and NFκB in U937 cells, it only activated NFκB in fibroblasts. Analysis of nuclear AP-1 subunits showed that LPS stimulated c-Fos, Fra-1 and Jun D activities in U937 cells, but not fibroblasts. The lack of ERK involvement in LPS-stimulated IL-6 in fibroblasts was further supported by the observations that simvastatin, which is known to target ERK-AP-1, failed to inhibit LPS-stimulated IL-6 by fibroblasts. Finally, we showed that targeting NFκB pathway was highly effective in inhibition of LPS-stimulated IL-6 in coculture of U937 cells and fibroblasts.
Inflammation; LPS; Cytokine; Gene expression; Signal transduction; Transcription
X-linked hyper-IgM syndrome (XHM) is a combined immune deficiency disorder caused by mutations in CD40 ligand. We tested CP-870,893, a human CD40 agonist monoclonal antibody, in the treatment of two XHM patients with biliary Cryptosporidiosis. CP-870,893 activated B cells and APCs in vitro, restoring class switch recombination in XHM B cells and inducing cytokine secretion by monocytes. CP-870,893 infusions were well tolerated and showed significant activity in vivo, decreasing leukocyte concentration in peripheral blood. Although specific antibody responses were lacking, frequent dosing in one subject primed T cells to secrete IFN-g and suppressed oocyst shedding in the stool. Nevertheless, relapse occurred after discontinuation of therapy. The CD40 receptor was rapidly internalized following binding with CP-870,893, potentially explaining the limited capacity of CP-870,893 to mediate immune reconstitution. This study demonstrates that CP-870,893 suppressed oocysts shedding in XHM patients with biliary cryptosporidiosis. The continued study of CD40 agonists in XHM is warranted.
X-linked hyper-IgM syndrome; CD40 ligand; CP-870; 893; CD40-R internalization
Emerging evidence suggests that there are IgM-autoantibodies that may play protective roles in SLE. While IgM are often considered polyreactive, we postulate that there are distinct sets of IgM-autoantibodies of defined autoreactive specificities relevant to different features of SLE. We examined the relationships between levels of IgM natural autoantibodies (NAbs) to apoptosis-associated phosphorylcholine (PC) or malondialdehyde (MDA) antigens, with lupus-associated autoantibodies and features of disease, in 120 SLE patients. IgM anti-PC was significantly higher in patients with low disease activity and less organ damage determined by the SELENA-SLEDAI, the physician's evaluation and the SLICC damage score. Furthermore, IgM anti-PC was significantly higher in patients without cardiovascular events. In contrast, IgM anti-cardiolipin and IgM anti-dsDNA were significantly higher in patients without renal disease. These results support the hypothesis that some IgM autoantibodies are part of a natural immune repertoire that provide homeostatic functions and protection from certain clinical lupus features.
Systemic lupus erythematosus; Natural antibodies; IgM; Cardiovascular disease; Renal disease
In rheumatoid arthritis (RA), hematopoietic progenitor cells (HPC) have age-inappropriate telomeric shortening suggesting premature senescence and possible restriction of proliferative capacity. In response to hematopoietic growth factors RA-derived CD34+ HPC expanded significantly less than age-matched controls. Cell surface receptors for stem cell factor (SCF), Flt 3-Ligand, IL-3 and IL-6 were intact in RA HPC but the cells had lower transcript levels of cell cycle genes, compatible with insufficient signal strength in the ERK pathway. Cytokine-induced phosphorylation of ERK1/2 was diminished in RA HPC whereas phosphorylated STAT3 and STAT5 molecules accumulated to a similar extent as in controls. Confocal microscopy demonstrated that the membrane-proximal colocalization of K-Ras and B-Raf were less efficient in RA-derived CD34+ cells. Thus, hyporesponsiveness of RA HPC to growth factors results from dampening of the ERK signaling pathways; with a defect localized in the very early steps of the ERK signaling cascade.
rheumatoid arthritis; hematopoietic progenitor cells; CD34; ERK signaling; STAT signaling
Deficiency of the IL-1 receptor antagonist (DIRA) is a recently described rare autoinflammatory disease, caused by loss of function mutations in IL1RN leading to the unopposed activation of the IL-1 pathway. We describe a novel nonsense mutation in the IL1RN gene, associated with early intrauterine onset, death and multiorgan involvement in a prematurely born baby. The protein prediction model indicated that the novel Q119X mutation would result in a nonfunctional protein by impairing the ability of the IL-1Ra to bind and antagonize signaling through the IL-1R. Since the disorder may mimic severe bacterial infections and the treatment with anakinra is life saving, we intend to raise awareness of the syndrome and the possibility of a founder mutation that may lead to the diagnosis of additional cases in Turkey. The clinical suspicion of DIRA is critical to avoid improper management of the patients with antibiotics alone and death from multiorgan failure.
Autoinflammatory syndrome; Deficiency of interleukin-1 receptor antagonist; Intrauterine onset; Immunodeficiency