Development Of Autoimmune Diseases Research Articles

Does Surgical Removal of the Thymus Have Deleterious Consequences?

The role of immunosenescence, particularly the natural process of thymic involution during aging, is increasingly acknowledged as a factor contributing to the development of autoimmune diseases and cancer. Recently, a concern has been raised about deleterious consequences of the surgical removal of thymic tissue, including for patients who undergo thymectomy for myasthenia gravis (MG) or resection of a thymoma. This review adopts a multidisciplinary approach to scrutinize the evidence concerning the long-term risks of cancer and autoimmunity postthymectomy. We conclude that for patients with acetylcholine receptor antibody-positive MG and those diagnosed with thymoma, the removal of the thymus offers prominent benefits that well outweigh the potential risks. However, incidental removal of thymic tissue during other thoracic surgeries should be minimized whenever feasible.

Autoimmune manifestations following COVID-19 infection in two individuals with primary immunodeficiency

Background: Due to widespread vaccination efforts worldwide, the mortality rates linked to COVID-19 have been decreasing. Nevertheless, there persists a notable level of morbidity, marked by increased occurrences of post-COVID-19 conditions. This includes the development of new autoimmune and inflammatory diseases in individuals who have recovered from COVID-19. A more severe progression of COVID-19 has been correlated with an increased probability of newly diagnosed autoimmune disease, and among individuals with preexisting autoimmune conditions, COVID-19 increased the risk of developing another autoimmune disease by 23%. Methods: Our patients’ medical records were analyzed retrospectively, including their medical history. Results: We present two cases of primary immunodeficiency patients. One of them experienced the onset of new autoimmune symptoms, while the other had a worsening of her autoimmune condition following COVID-19 infection. Conclusion: Recognizing the potential connection between COVID-19 and autoimmune conditions is crucial for identifying symptoms promptly in primary immunodeficiency patients and ensuring timely treatment. Further research is required to comprehensively grasp the relationship between COVID-19 and the development of autoimmunity in this particular patient group. Statement of Novelty: In this paper, we present a novel exploration into the emergence of autoimmune manifestations in primary immunodeficiency patients subsequent to COVID-19 infection, through an analysis of two distinct case reports.

Development of Clarstatin, a Novel Drug Lead for the Therapy of Autoimmune Uveitis

We describe the design, synthesis, and activity of a potent thiourea-bridged backbone cyclic peptidomimetic known as Clarstatin, comprising a 5-amino acid sequence (Q/D)1-(R/K)2-X3-X4-A5-(Gln/Asp)1-(Arg/Lys)2-AA3-AA4-Ala5-based on a motif called “shared epitope (SE)”, specifically present in specific alleles of the HLA-DRB1 gene. This SE binds to a particular site within the proline reach domain (P-domain) of the cell surface-calreticulin (CS-CRT). CS-CRT is a multifunctional endoplasmic reticulum (ER) calcium-binding protein that is located on the cell surface of T cells and triggers innate immune signaling, leading to the development of inflammatory autoimmune diseases. The development of Clarstatin was based on the parent peptide W-G-D1-K2-S3-G4-A5- derived from the active region of the SE. Following the design based on the cycloscan method, the synthesis of Clarstatin was performed by the Fmoc solid phase peptide synthesis (SPPS) method, purified by HPLC to 96% homogeneity, and its structure was confirmed by LC-MS. Clarstatin reduced calcium levels in Jurkat lymphocyte cultures, ameliorated uveitis in vivo in the experimental autoimmune uveitis (EAU) mice model, and was safe upon acute toxicity evaluation. These findings identify Clarstatin as a promising lead compound for future drug development as a novel class of therapeutic agents in the therapy of uveitis.

Elucidating the role of T-Reg related cytokines: serum transforming growth factor beta and interleukin-35 in alopecia areata.

Previous studies demonstrated that Th1 cytokines like IL-2, IL-12 and IFN-γ have initiatory role in alopecia areata (AA) and positive correlation with disease severity. They informed that serum levels of Th17 cytokines, IL-17, IL-22, IL-23 increased in active AA patients and corelated, particularly IL-17, with disease severity. In recent reports it was showed the balance between Th17 and Treg cells is crucial for maintaining tolerance to self-antigens, and an imbalance towards Th17 may contribute to the development of autoimmune diseases like AA. But research on serum Treg markers in AA is limited. It was aimed to investigate whether the Treg cells have a role in the pathogenesis of AA analyzing the serum levels of Treg cytokines IL-35 and TGF-β in the patients with AA. 42 AA patients and 38 healthy controls were enrolled. Patient demographics, clinical data, disease severity assessed by Severity of Alopecia Tool (SALT) scores were recorded. Serum samples were collected and analyzed for TGF-β and IL-35 levels using ELISA kits. The cytokine levels in both groups were statistically compared. Their relation with parameters of demographic and severity of disease was evaluated. The patient and control groups had no statistically significant difference, there was 71.4% males and 28.6% females in patient group, while the control group had 63.2% males and 36.8% females, Severity analysis classified 18 patients with mild AA, 19 with moderate AA, and 5 with alopecia totalis/areata universalis. While TGF-β levels exhibited no significant difference between groups, IL-35 levels were significantly elevated in AA patients (p = 0.002). Logistic regression identified IL-35 as a significant parameter influencing disease status (OR = 1.055). Correlation analysis revealed a weak positive correlation between patient age and IL-35 levels (r = 0.436; p = 0.004). Notably, IL-35 levels displayed a significant decrease in individuals with antinuclear antibody (ANA) positivity. No correlations were identified between cytokine levels and disease severity, prognosis, or disease activity. Elevated IL-35 levels suggest that IL-35 and specific Treg cell subsets can play a role in AA pathogenesis. The nuanced roles of TGF-β and IL-35 highlight the need for comprehensive studies to interpret their implications in the complex immunopathogenesis of AA. These findings open avenues for further research, positioning IL-35 as a prospective target for investigating and potentially intervening in AA pathogenesis.

#271 The nexus between TMA/TTP, MIS-C, and SLE

Abstract Background and Aims The long-term complications of COVID-19 infection & Multisystem inflammatory syndrome in children (MIS-C) on immune system are still unknown, however there're reports on development of autoimmune disease, highlighting their immune-related nature. MIS-C can induce Thrombotic Microangiopathy (TMA), by inducing endothelial dysfunction, platelet activation, & microthrombi formation, whereas SLE induces TMA/Thrombotic thrombocytopenic purpura (TTP), with ADAMTS13 activity < 10%, or 2ry TMA with ADAMTS13 activity ≥ 10%, where SLE/TTP carries a bad prognosis. Method Our case is one of its kind, where a 12-year- old girl, who was previously infected with SARS-CoV-2, presented with new-onset SLE, associated MIS-C & 2ry TMA/TTP. She presented with convulsions, oliguria, heart failure, impaired kidney function, microangiopathic hemolytic anemia, pancytopenia, highly elevated LDH, & was diagnosed as TMA. Results COVID serology was +ve for IgG, & -ve for IgM, & -ve SARS-CoV-2 PCR, a diagnosis of MIS-C was postulated. Further investigations revealed low C3, C4, +ve ANA, anti-ds DNA & anti-phospholipid Antibodies. Brain imaging showed left cerebellar calcification. Echocardiography showed biventricular dysfunction with EF 30%, where the diagnosis of SLE according to Euler/ACR criteria was confirmed, with 2ry TMA. Emergency hemodialysis, PRBCs transfusion, pulse steroid with total plasma exchange (TPE), were initiated without marked improvement. Rituximab was started on 4th day, but she had generalized convulsion, arrythmia & sudden death occurred. Results of ADAMTS13 activity was < 1%, with +ve autoantibodies, so diagnosis of TMA/TTP was confirmed. Conclusion TMA are a diverse group of disorders that causes microvasculature thrombosis, which is inherited, or acquired 2ry to SLE or COVID-19 infection, where high index of suspicions should be raised for early diagnosis and prompt management, meanwhile COVID-19 infection can induce the development of autoimmune diseases. Herein we raise the question of cause of TMA/TTP, was it 2ry only SLE, or to the previous COVID-19 infection & MIS-C, and if this SLE itself was 2ry also to the previous COVID infection, or all it was by chance?

Downregulation of Ebp1Khib210 promotes keratinocyte proliferation through induction of TIF-IA-mediated rRNA synthesis.

Psoriasis is a prevalent chronic inflammatory dermatosis characterized by excessive proliferation of keratinocytes. Protein lysine 2-hydroxyisobutyrylation (Khib) is a newly identified post-translational modification that regulates various biological processes. Abnormal Khib modification has been closely associated with the development of autoimmune diseases. To investigate the abnormal Khib profile and its pathogenic role in psoriasis. We utilized liquid chromatography-tandem mass spectrometry to analyze Khib-modified proteins in the epidermis of psoriasis and healthy controls. Mutated cells and mice with downregulated Ebp1Khib210 were generated to investigate its functional effects in psoriasis. The omic analysis revealed dysregulation of Khib modification in psoriatic lesions, exhibiting a distinct profile compared to controls. We observed the downregulation of Ebp1Khib210 in psoriatic lesions and IMQ-induced psoriatic mice. Notably, the expression of Ebp1Khib210 was upregulated in psoriatic patients following effective treatment. Decreased Ebp1Khib210 enhanced keratinocyte viability, proliferation, and survival while inhibiting apoptosis in vitro. Additionally, Pa2g4K210A mice with downregulated Ebp1Khib210 exhibited more severe psoriatic lesions and enhanced keratinocyte proliferation. Moreover, we found that Ebp1K210A mutation increased the interaction between Ebp1 and nuclear Akt, thereby inhibiting MDM2-mediated TIF-IA ubiquitination, and resulting to increased rRNA synthesis and keratinocyte proliferation. The downregulation of Ebp1Khib210 was attributed to inflammation-induced increases in HDAC2 expression. Our findings demonstrate that downregulation of Ebp1Khib210 promotes keratinocyte proliferation through modulation of Akt signaling and TIF-IA-mediated rRNA synthesis. These insights into Khib modification provide a better understanding of the pathogenesis of psoriasis and suggest potential therapeutic targets.

Management and Long-Term Outcomes of Drug Reaction with Eosinophilia and Systemic Symptoms (DReSS) in Children: A Scoping Review.

Drug reaction with eosinophilia and systemic symptoms (DReSS) is known to cause mortality and long-term sequelae in the pediatric population, however there are no established clinical practice guidelines for the management of pediatric DReSS. We conducted a scoping review, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, to summarize the currently available data on treatment, mortality, and long-term sequelae of DReSS in children (aged 0-18 years). Data from 644 individuals revealed that various treatment strategies are being used in the management of pediatric DReSS, and strategies were often used in combination. The diversity in treatment approaches cannot be solely attributed to age or disease severity and reflects the lack of evidence-based management guidelines for DReSS. Children are also at risk of developing autoimmune sequelae following DReSS, most commonly thyroid disease and type 1 diabetes mellitus. We found that the eventual development of autoimmune disease was more often associated with DReSS caused by antibiotics, especially minocycline and sulfamethoxazole, in comparison with individuals who did not develop sequelae. In this study, we identify strengths and weaknesses in the currently available literature and highlight that future prospective studies with structured and long-term follow-up of children with DReSS are needed to better understand potential risk factors for mortality and development of sequelae after DReSS.

A rare post-infectious autoimmune manifestation of COVID-19

The incidence of post-infectious autoimmune diseases has been on the rise following the COVID-19 pandemic. Recently, an autistic patient was admitted to the hospital presenting with a mild upper respiratory system COVID-19 infection. Months after recovery and polymerase chain reaction negativity, the patient developed HEp-2 cell positivity and presented with relapsing polychondritis (RP), a rare autoimmune disease. The mechanism of this autoimmune invasion is ultimately caused by activating a myriad of immune reactions. Lymphocytopenia almost always accompanies various clinical forms of COVID-19; however, it may drive the lymphocytopenia-induced proliferation of autoreactive T cells via the activation of interleukin-6 (IL-6). Moreover, high levels of neutrophils during infection promote autoimmune disease by releasing cytokine and chemokine cascades that accompany inflammation, and neutrophil extracellular traps regulating immune responses through cell–cell interactions. Furthermore, autism spectrum disorder patients display an altered immune system that includes an augmented inflammatory cytokine milieu leading to an increased pro-inflammatory Th1/Th2 ratio. In addition, the pathophysiology of RP is majorly associated with a cell-mediated immune reaction; thus, the predisposing exaggerated immune system of such patients must also be considered as a predisposing factor to the development of post-infectious autoimmune diseases.

Microbial influences on severity and sex bias of systemic autoimmunity.

Commensal microbes have the capacity to affect development and severity of autoimmune diseases. Germ-free (GF) animals have proven to be a fine tool to obtain definitive answers to the queries about the microbial role in these diseases. Moreover, GF and gnotobiotic animals can be used to dissect the complex symptoms and determine which are regulated (enhanced or attenuated) by microbes. These include disease manifestations that are sex biased. Here, we review comparative analyses conducted between GF and Specific-Pathogen Free (SPF) mouse models of autoimmunity. We present data from the B6;NZM-Sle1NZM2410/AegSle2NZM2410/AegSle3NZM2410/Aeg-/LmoJ (B6.NZM) mouse model of systemic lupus erythematosus (SLE) characterized by multiple measurable features. We compared the severity and sex bias of SPF, GF, and ex-GF mice and found variability in the severity and sex bias of some manifestations. Colonization of GF mice with the microbiotas taken from B6.NZM mice housed in two independent institutions variably affected severity and sexual dimorphism of different parameters. Thus, microbes regulate both the severity and sexual dimorphism of select SLE traits. The sensitivity of particular trait to microbial influence can be used to further dissect the mechanisms driving the disease. Our results demonstrate the complexity of the problem and open avenues for further investigations.

Immune Regulation by TNF Receptor-associated Factor 5

The tumor necrosis factor receptor (TNFR)-associated factor (TRAF) family of molecules are intracellular adaptors that regulate cellular signaling through members of the TNFR and Toll-like receptor superfamily. Mammals have seven TRAF molecules numbered sequentially from TRAF1 to TRAF7. Although TRAF5 was identified as a potential regulator of TNFR superfamily members, the in vivo function of TRAF5 has not yet been fully elucidated. We identified an unconventional role of TRAF5 in interleukin-6 (IL-6) receptor signaling involving CD4+ T cells. Moreover, TRAF5 binds to the signal-transducing glycoprotein 130 (gp130) receptor for IL-6 and inhibits the activity of the janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway. In addition, Traf5-deficient CD4+ T cells exhibit significantly enhanced IL-6-driven differentiation of T helper 17 (Th17) cells, which exacerbates neuroinflammation in experimental autoimmune encephalomyelitis. Furthermore, TRAF5 demonstrates a similar activity to gp130 for IL-27, another cytokine of the IL-6 family. Additionally, Traf5-deficient CD4+ T cells display significantly increased IL-27-mediated differentiation of Th1 cells, which increases footpad swelling in delayed-type hypersensitivity response. Thus, TRAF5 functions as a negative regulator of gp130 in CD4+ T cells. This review aimed to explain how TRAF5 controls the differentiation of CD4+ T cells and discuss how the expression of TRAF5 in T cells and other cell types can influence the development and progression of autoimmune and inflammatory diseases.

Toll-like receptors in health and disease.

Toll-like receptors (TLRs) are inflammatory triggers and belong to a family of pattern recognition receptors (PRRs) that are central to the regulation of host protective adaptive immune responses. Activation of TLRs in innate immune myeloid cells directs lymphocytes to produce the most appropriate effector responses to eliminate infection and maintain homeostasis of the body's internal environment. Inappropriate TLR stimulation can lead to the development of general autoimmune diseases as well as chronic and acute inflammation, and even cancer. Therefore, TLRs are expected to be targets for therapeutic treatment of inflammation-related diseases, autoimmune diseases, microbial infections, and human cancers. This review summarizes the recent discoveries in the molecular and structural biology of TLRs. The role of different TLR signaling pathways in inflammatory diseases, autoimmune diseases such as diabetes, cardiovascular diseases, respiratory diseases, digestive diseases, and even cancers (oral, gastric, breast, colorectal) is highlighted and summarizes new drugs and related clinical treatments in clinical trials, providing an overview of the potential and prospects of TLRs for the treatment of TLR-related diseases.

Modelling the Impact of NETosis During the Initial Stage of Systemic Lupus Erythematosus

The development of autoimmune diseases often takes years before clinical symptoms become detectable. We propose a mathematical model for the immune response during the initial stage of Systemic Lupus Erythematosus which models the process of aberrant apoptosis and activation of macrophages and neutrophils. NETosis is a type of cell death characterised by the release of neutrophil extracellular traps, or NETs, containing material from the neutrophil’s nucleus, in response to a pathogenic stimulus. This process is hypothesised to contribute to the development of autoimmunogenicity in SLE. The aim of this work is to study how NETosis contributes to the establishment of persistent autoantigen production by analysing the steady states and the asymptotic dynamics of the model by numerical experiment.

Prenatal exposure to environmental contaminants and cord serum metabolite profiles in future immune-mediated diseases.

Prenatal exposure to environmental contaminants is a significant health concern because it has the potential to interfere with host metabolism, leading to adverse health effects in early childhood and later in life. Growing evidence suggests that genetic and environmental factors, as well as their interactions, play a significant role in the development of autoimmune diseases. In this study, we hypothesized that prenatal exposure to environmental contaminants impacts cord serum metabolome and contributes to the development of autoimmune diseases. We selected cord serum samples from All Babies in Southeast Sweden (ABIS) general population cohort, from infants who later developed one or more autoimmune-mediated and inflammatory diseases: celiac disease (CD), Crohn's disease (IBD), hypothyroidism (HT), juvenile idiopathic arthritis (JIA), and type 1 diabetes (T1D) (all cases, N = 62), along with matched controls (N = 268). Using integrated exposomics and metabolomics mass spectrometry (MS) based platforms, we determined the levels of environmental contaminants and metabolites. Differences in exposure levels were found between the controls and those who later developed various diseases. High contaminant exposure levels were associated with changes in metabolome, including amino acids and free fatty acids. Specifically, we identified marked associations between metabolite profiles and exposure levels of deoxynivalenol (DON), bisphenol S (BPS), and specific per- and polyfluorinated substances (PFAS). Abnormal metabolism is a common feature preceding several autoimmune and inflammatory diseases. However, few studies compared common and specific metabolic patterns preceding these diseases. Here we hypothesized that exposure to environmental contaminants impacts cord serum metabolome, which may contribute to the development of autoimmune diseases. We found differences in exposure levels between the controls and those who later developed various diseases, and importantly, on the metabolic changes associated with the exposures. High contaminant exposure levels were associated with specific changes in metabolome. Our study suggests that prenatal exposure to specific environmental contaminants alters the cord serum metabolomes, which, in turn, might increase the risk of various immune-mediated diseases.

Are single nucleotide polymorphisms in the IL-2 gene biomarkers for Hashimoto's thyroiditis?

Hashimoto's thyroiditis (HT) is an autoimmune disorder that can lead to hypothyroidism. The pathophysiology of HT involves the production of antithyroid antibodies that attack the thyroid tissue, causing inflammation and progressive fibrosis. Recent studies demonstrated a strong correlation between Interleukin-2 (IL-2) levels and the development of autoimmune diseases, suggesting that this cytokine may play a crucial role in the pathogenesis of HT. In this study, we determined the presence of the point mutation +114T/G in the IL-2 gene in patients with HT compared with a control group, and also the serum level of anti-thyroid peroxidase (TPOAbs) and anti-thyroglobulin (TgAbs) antibodies in HT patients with vs. without the mutation. The sequences of the IL-2 gene obtained from subjects were determined by the Sanger sequencing method. Our study did not reveal that the +114T/G polymorphism of the IL-2 gene is a susceptibility or protective factor for HT. No significant correlations were observed between the reference genotype, hetero- and homozygous +114T/G polymorphism and TPOAbs, respectively TgAbs serum levels in HT patients. Further studies of more cases are needed to identify more polymorphisms in the IL-2 gene and study their correlations with HT.

Does vitamin D decrease the development of autoimmune disease?

Does vitamin D decrease the development of autoimmune disease?

Contributions of Synthetic Chemicals to Autoimmune Disease Development and Occurrence.

Exposure to many synthetic chemicals has been linked to a variety of adverse human health effects, including autoimmune diseases. In this scoping review, we summarize recent evidence detailing the effects of synthetic environmental chemicals on autoimmune diseases and highlight current research gaps and recommendations for future studies. We identified 68 recent publications related to environmental chemical exposures and autoimmune diseases. Most studies evaluated exposure to persistent environmental chemicals and autoimmune conditions including rheumatoid arthritis (RA), systemic lupus (SLE), systemic sclerosis (SSc), and ulcerative colitis (UC) and Crohn's disease. Results of recent original research studies were mixed, and available data for some exposure-outcome associations were particularly limited. PFAS and autoimmune inflammatory bowel diseases (UC and CD) and pesticides and RA appeared to be the most frequently studied exposure-outcome associations among recent publications, despite a historical research focus on solvents. Recent studies have provided additional evidence for the associations of exposure to synthetic chemicals with certain autoimmune conditions. However, impacts on other autoimmune outcomes, particularly less prevalent conditions, remain unclear. Owing to the ubiquitous nature of many of these exposures and their potential impacts on autoimmune risk, additional studies are needed to better evaluate these relationships, particularly for understudied autoimmune conditions. Future research should include larger longitudinal studies and studies among more diverse populations to elucidate the temporal relationships between exposure-outcome pairs and to identify potential population subgroups that may be more adversely impacted by immune modulation caused by exposure to these chemicals.

IL-22, a vital cytokine in autoimmune diseases.

Interleukin-22 (IL-22) is a vital cytokine that is dysregulated in various autoimmune conditions including rheumatoid arthritis (RA), multiple sclerosis (MS), and Alzheimer's disease (AD). As the starting point for the activation of numerous signaling pathways, IL-22 plays an important role in the initiation and development of autoimmune diseases. Specifically, imbalances in IL-22 signaling can interfere with other signaling pathways, causing cross regulation of target genes which ultimately leads to the development of immune disorders. This review delineates the various connections between the IL-22 signaling pathway and autoimmune disease, focusing on the latest understanding of the cellular sources of IL-22 and its effects on various cell types. We further explore progress with pharmacological interventions related to targeting IL-22, describing how such therapeutic strategies promise to usher in a new era in the treatment of autoimmune disease.

Anything that can go wrong: cytotoxic cells and their control of Epstein-Barr virus

Epstein-Barr virus (EBV) is an gamma of herpes virus affecting exclusively humans, was the first oncogenic virus described and is associated with over seven different cancers. Curiously, the exchange of genes during viral infections has enabled the evolution of other cellular organisms, favoring new functions and the survival of the host. EBV has been co-evolving with mammals for hundreds of millions of years, and more than 95% of adults have been infected in one moment of their life. The infection is acquired primarily during childhood, in most cases as an asymptomatic infection. However, during adolescence or young adulthood, around 10 to 30% develop infectious mononucleosis. The NK and CD8+ T cells are the cytotoxic cells of the immune system that focus on antiviral responses. Importantly, an essential role of NK and CD8+ T cells has been demonstrated during the control and elimination of EBV-infected cells. Nonetheless, when the cytotoxic function of these cells is compromised, the infection increases the risk of developing lymphoproliferative diseases and cancer, often fatal. In this review, we delineate EBV infection and the importance of cytotoxic responses by NK and CD8+ T cells during the control and elimination of EBV-infected cells. Furthermore, we briefly discuss the main inborn errors of immunity that compromise cytotoxic responses by NK and CD8+ T cells, and how this scenario affects the antiviral response during EBV infection. Finally, we conclude the review by underlying the need for an effective EBV vaccine capable of preventing infection and the consequent development of malignancies and autoimmune diseases.

Simultaneous deletion of ORMDL1 and ORMDL3 proteins disrupts immune cell homeostasis.

ORMDL3 is a prominent member of a family of highly conserved endoplasmic reticulum resident proteins, ORMs (ORM1 and ORM2) in yeast, dORMDL in Drosophila and ORMDLs (ORMDL1, ORMDL2, and ORMDL3) in mammals. ORMDL3 mediates feedback inhibition of de novo sphingolipid synthesis. Expression levels of ORMDL3 are associated with the development of inflammatory and autoimmune diseases including asthma, systemic lupus erythematosus, type 1 diabetes mellitus and others. It has been shown that simultaneous deletions of other ORMDL family members could potentiate ORMDL3-induced phenotypes. To understand the complex function of ORMDL proteins in immunity in vivo, we analyzed mice with single or double deletions of Ormdl genes. In contrast to other single and double knockouts, simultaneous deletion of ORMDL1 and ORMDL3 proteins disrupted blood homeostasis and reduced immune cell content in peripheral blood and spleens of mice. The reduced number of splenocytes was not caused by aberrant immune cell homing. A competitive bone marrow transplantation assay showed that the development of Ormdl1-/-/Ormdl3-/- B cells was dependent on lymphocyte intrinsic factors. Highly increased sphingolipid production was observed in the spleens and bone marrow of Ormdl1-/-/Ormdl3-/- mice. Slight, yet significant, increase in some sphingolipid species was also observed in the spleens of Ormdl3-/- mice and in the bone marrow of both, Ormdl1-/- and Ormdl3-/- single knockout mice. Taken together, our results demonstrate that the physiological expression of ORMDL proteins is critical for the proper development and circulation of lymphocytes. We also show cell-type specific roles of individual ORMDL family members in the production of different sphingolipid species.

Apoptosis of Dendritic Cells and Autoimmune Disease.

Dendritic cells (DCs), the most efficient antigen-presenting cells (APCs), bridge the innate and adaptive immune systems. As such, the turn-over of DCs is critical during autoimmune responses, and the dysregulation of DC apoptosis could cause severe immune destruction in the host. For example, reduction of immunogenic DCs by increased apoptosis could lead to immune tolerance to pathogen infection that might allow exposure of nuclear autoantigens, whereas reduced apoptosis could result in long-term lymphocyte activation to break the immune tolerance for the development of autoimmune disease. Thus, keeping a balance between survival and apoptosis of DCs is crucial to maintain immune homeostasis. In this review, we summarize the recent development on the factors inducing DC apoptosis and their underlying mechanisms to provide insights into the immunopathogenesis of some autoimmune diseases, which could lead to effective therapeutic interventions in the clinics.