PDIA3 orchestrates effector T cell program by serving as a chaperone to facilitate the non-canonical nuclear import of STAT1 and PKM2.

Dysregulated T cell activation underpins the immunopathology of rheumatoid arthritis (RA), yet the machineries that orchestrate T cell effector program remain incompletely understood. Herein, we leveraged bulk and single-cell RNA sequencing data from RA patients and validated protein disulfide isomerase family A member 3 (PDIA3) as a potential therapeutic target. PDIA3 is remarkably upregulated in pathogenic CD4 T cells derived from RA patients and positively correlates with C-reactive protein level and disease activity score 28. Pharmacological inhibition or genetic ablation of PDIA3 alleviates RA-associated articular pathology and autoimmune responses. Mechanistically, T cell receptor signaling triggers intracellular calcium flux to activate NFAT1, a process that is further potentiated by Wnt5a under RA settings. Activated NFAT1 then directly binds to the Pdia3 promoter to enhance the expression of PDIA3, which complexes with STAT1 or PKM2 to facilitate their nuclear import for transcribing T helper 1 (Th1) and Th17 lineage-related genes, respectively. This non-canonical regulatory mechanism likely occurs under pathological conditions, as PDIA3 could only be highly induced following aberrant external stimuli. Together, our data support that targeting PDIA3 is a vital strategy to mitigate autoimmune diseases, such as RA, in clinical settings.

Fluvoxamine inhibits Th1 and Th17 polarization and function by repressing glycolysis to attenuate autoimmune progression in type 1 diabetes.

BACKGROUND: Fluvoxamine is one of the selective serotonin reuptake inhibitors (SSRIs) that are regarded as the first-line drugs to manage mental disorders. It has been also recognized with the potential to treat inflammatory diseases and viral infection. However, the effect of fluvoxamine on autoimmune diseases, particularly type 1 diabetes (T1D) and the related cellular and molecular mechanisms, are yet to be addressed. METHOD: Herein in this report, we treated NOD mice with fluvoxamine for 2 weeks starting from 10-week of age to dissect the impact of fluvoxamine on the prevention of type 1 diabetes. We compared the differences of immune cells between 12-week-old control and fluvoxamine-treated mice by flow cytometry analysis. To study the mechanism involved, we extensively examined the characteristics of CD4+ T cells with fluvoxamine stimulation using RNA-seq analysis, real-time PCR, Western blot, and seahorse assay. Furthermore, we investigated the relevance of our data to human autoimmune diabetes. RESULT: Fluvoxamine not only delayed T1D onset, but also decreased T1D incidence. Moreover, fluvoxamine-treated NOD mice showed significantly attenuated insulitis coupled with well-preserved ß cell function, and decreased Th1 and Th17 cells in the peripheral blood, pancreatic lymph nodes (PLNs), and spleen. Mechanistic studies revealed that fluvoxamine downregulated glycolytic process by inhibiting phosphatidylinositol 3-kinase (PI3K)-AKT signaling, by which it restrained effector T (Teff) cell differentiation and production of proinflammatory cytokines. CONCLUSION: Collectively, our study supports that fluvoxamine could be a viable therapeutic drug against autoimmunity in T1D setting.

SUMOylation, a multifaceted regulatory mechanism in the pancreatic beta cells.

SUMOylation is an evolutionarily conserved post-translational modification (PTM) that regulates protein subcellular localization, stability, conformation, transcription and enzymatic activity. Recent studies indicate that SUMOylation plays a key role in insulin gene expression, glucose metabolism and insulin exocytosis under physiological conditions in the pancreatic beta cells. Furthermore, SUMOylation is implicated in beta cell survival and recovery following exposure to oxidative stress, ER stress and inflammatory mediators under pathological situations. SUMOylation is closely regulated by the cellular redox status, and it collaborates with other PTMs such as phosphorylation, ubiquitination, and NEDDylation, to maintain beta cellular homeostasis. We hereby provide an update on recent findings regarding the role of SUMOylation in the regulation of pancreatic beta cell viability and function, and discuss its potential implication in beta cell senescence and RNA processing (e.g., pre-mRNA splicing and mRNA methylation). Through which we intend to provide novel insights into this fundamental biological process regarding both maintenance of beta cell viability and functionality, and beta cell dysfunction in diabetes mellitus.

Upregulated hexokinase 2 expression induces the apoptosis of dopaminergic neurons by promoting lactate production in Parkinson's disease.

Parkinson's disease (PD) is characterized by impaired mitochondrial function and decreased ATP levels. Aerobic glycolysis and lactate production have been shown to be upregulated in dopaminergic neurons to sustain ATP levels, but the effect of upregulated glycolysis on dopaminergic neurons remains unknown. Since lactate promotes apoptosis and α-synuclein accumulation in neurons, we hypothesized that the lactate produced upon upregulated glycolysis is involved in the apoptosis of dopaminergic neurons in PD. In this study, we examined the expression of hexokinase 2 (HK2) and lactate dehydrogenase (LDH), the key enzymes in glycolysis, and lactate levels in the substantia nigra pars compacta (SNpc) of a MPTP-induced mouse model of PD and in MPP+-treated SH-SY5Y cells. We found that the expression of HK2 and LDHA and the lactate levels were markedly increased in the SNpc of MPTP-treated mice and in MPP+-treated SH-SY5Y cells. Exogenous lactate treatment led to the apoptosis of SH-SY5Y cells. Intriguingly, lactate production and the apoptosis of dopaminergic neurons were suppressed by the application of 3-bromopyruvic acid (3-Brpa), a HK2 inhibitor, or siRNA both in vivo and in vitro. 3-Brpa treatment markedly improved the motor behaviour of MPTP-treated mice in pole test and rotarod test. Mechanistically, lactate increases the activity of adenosine monophosphate-activated protein kinase (AMPK) and suppresses the phosphorylation of serine/threonine kinase 1 (Akt) and mammalian target of rapamycin (mTOR). Together, our data suggest that upregulated HK2 and LDHA and increased lactate levels prompt the apoptosis of dopaminergic neurons in PD. Inhibition of HK2 expression attenuated the apoptosis of dopaminergic neurons by downregulating lactate production and AMPK/Akt/mTOR pathway in PD.

The methyl-CpG-binding domain 2 facilitates pulmonary fibrosis by orchestrating fibroblast to myofibroblast differentiation.

Although DNA methylation has been recognised in the pathogenesis of idiopathic pulmonary fibrosis (IPF), the exact mechanisms are yet to be fully addressed. Herein, we demonstrate that lungs originated from IPF patients and mice after bleomycin (BLM)-induced pulmonary fibrosis are characterised by altered DNA methylation along with overexpression in myofibroblasts of methyl-CpG-binding domain 2 (MBD2), a reader responsible for interpreting DNA methylome-encoded information. Specifically, depletion of Mbd2 in fibroblasts or myofibroblasts protected mice from BLM-induced pulmonary fibrosis coupled with a significant reduction of fibroblast differentiation. Mechanistically, transforming growth factor (TGF)-ß1 induced a positive feedback regulatory loop between TGF-ß receptor I (TßRI), Smad3 and Mbd2, and erythroid differentiation regulator 1 (Erdr1). TGF-ß1 induced fibroblasts to undergo a global DNA hypermethylation along with Mbd2 overexpression in a TßRI/Smad3 dependent manner, and Mbd2 selectively bound to the methylated CpG DNA within the Erdr1 promoter to repress its expression, through which it enhanced TGF-ß/Smad signalling to promote differentiation of fibroblast into myofibroblast and exacerbate pulmonary fibrosis. Therefore, enhancing Erdr1 expression strikingly reversed established pulmonary fibrosis. Collectively, our data support that strategies aimed at silencing Mbd2 or increasing Erdr1 could be viable therapeutic approaches for prevention and treatment of pulmonary fibrosis in clinical settings.

The interferon regulatory factors, a double-edged sword, in the pathogenesis of type 1 diabetes.

Type 1 diabetes (T1D) is an autoimmune disease resulted from the unrestrained inflammatory attack towards the insulin-producing islet ß cells. Although the exact etiology underlying T1D remains elusive, viral infections, especially those specific strains of enterovirus, are acknowledged as a critical environmental cue involved in the early phase of disease initiation. Viral infections could either directly impede ß cell function, or elicit pathological autoinflammatory reactions for ß cell killing. Autoimmune responses are bolstered by a massive body of virus-derived exogenous pathogen-associated molecular patterns (PAMPs) and the presence of ß cell-derived damage-associated molecular patterns (DAMPs). In particular, the nucleic acid components and the downstream nucleic acid sensing pathways serve as the major effector mechanism. The endogenous retroviral RNA, mitochondrial DNA (mtDNA) and genomic fragments generated by stressed or dying ß cells induce host responses reminiscent of viral infection, a phenomenon termed as viral mimicry during the early stage of T1D development. Given that the interferon regulatory factors (IRFs) are considered as hub transcription factors to modulate immune responses relevant to viral infection, we thus sought to summarize the critical role of IRFs in T1D pathogenesis. We discuss with focus for the impact of IRFs on the sensitivity of ß cells to cytokine stimulation, the vulnerability of ß cells to viral infection/mimicry, and the intensity of immune response. Together, targeting certain IRF members, alone or together with other therapeutics, could be a promising strategy against T1D.

The role of hydrogen sulphide signalling in macrophage activation.

Hydrogen sulphide (H2 S) is the latest identified small gaseous mediator enabled by its lipophilic nature to freely permeate the biological membranes. Initially, H2 S was recognized by its roles in neuronal activity and vascular relaxation, which makes it an important molecule involved in paracrine signalling pathways. Recently, the immune regulatory function of gasotransmitters, H2 S in particular, is increasingly being appreciated. Endogenous H2 S level has been linked to macrophage activation, polarization and inflammasome formation. Mechanistically, H2 S-induced protein S-sulphydration suppresses several inflammatory pathways including NF-κB and JNK signalling. Moreover, H2 S serves as a potent cellular redox regulator to modulate epigenetic alterations and to promote mitochondrial biogenesis in macrophages. Here in this review, we intend to summarize the recent advancements of H2 S studies in macrophages, and to discuss with focus on the therapeutic potential of H2 S donors by targeting macrophages. The feasibility of H2 S signalling component as a macrophage biomarker under disease conditions would be also discussed.

Adult-onset type 1 diabetic patients with less severe clinical manifestation have less risk DR-DQ genotypes than childhood-onset patients.

BACKGROUND: The aim of this study was to investigate differences in clinical features and HLA genotypes between adult-onset and childhood-onset patients with type 1 diabetes in a Chinese population. MATERIALS AND METHODS: This study enrolled 716 Han Chinese patients with type 1 diabetes from Guangdong (258 childhood-onset and 458 adult-onset) to compare their clinical features. Of them 214 patients with classical type 1 diabetes (100 childhood-onset and 114 adult-onset) were selected for HLA DR and DQ genotyping by next-generation sequencing. RESULTS: Adult-onset patients were characterized by longer duration of symptoms before diagnosis, lower frequency of DKA at disease onset, less frequent autoantibody positivity, higher serum C-peptide concentrations, and better glycemic control. These findings were replicated in the restricted cohort of 214 patients with classical type 1 diabetes. Compared with childhood-onset patients, adult-onset patients had a lower frequency of the DR9 haplotype, as well as lower frequency of high-risk DR3/DR4 and DR3/DR9 genotypes, but higher frequency of DR3/DR3 genotype and DR3/X, DR4/X or DR9/X (X, non-risk) genotypes. CONCLUSIONS: Adult-onset type 1 diabetic patients with susceptible haplotypes (DR3, DR4 or DR9) were more likely to carry protective DR-DQ haplotypes than childhood-onset patients, which suggested the association between less risk DR-DQ genotypes and the less severe clinical manifestation in adult-onset patients.

Correction to: CX3CR1 positively regulates BCR signaling coupled with cell metabolism via negatively controlling actin remodeling.

In the original published version of the article, the red squares in the figures which indicated the corrections.

CX3CR1 positively regulates BCR signaling coupled with cell metabolism via negatively controlling actin remodeling.

As an important chemokine receptor, the role of CX3CR1 has been studied extensively on the migration of lymphocytes including T and B cells. Although CX3CR1+ B cells have immune suppressor properties, little is known about its role on the regulation of BCR signaling and B cell differentiation as well as the underlying molecular mechanism. We have used CX3CR1 KO mice to study the effect of CX3CR1 deficiency on BCR signaling and B cell differentiation. Interestingly, we found that proximal BCR signaling, such as the activation of CD19, BTK and SHIP was reduced in CX3CR1 KO B cells upon antigenic stimulation. However, the activation of mTORC signaling was enhanced. Mechanistically, we found that the reduced BCR signaling in CX3CR1 KO B cells was due to reduced BCR clustering, which is caused by the enhanced actin accumulation by the plasma membrane via increased activation of WASP. This caused an increased differentiation of MZ B cells in CX3CR1 KO mice and an enhanced generation of plasma cells (PC) and antibodies. Our study shows that CX3CR1 regulates BCR signaling via actin remodeling and affects B cell differentiation and the humoral immune response.

Extracellular HMGB1 exacerbates autoimmune progression and recurrence of type 1 diabetes by impairing regulatory T cell stability.

AIMS/HYPOTHESIS: High-mobility group box 1 (HMGB1), an evolutionarily conserved chromosomal protein, was rediscovered to be a 'danger signal' (alarmin) that alerts the immune system once released extracellularly. Therefore, it has been recognised contributing to the pathogenesis of autoimmune diabetes, but its exact impact on the initiation and progression of type 1 diabetes, as well as the related molecular mechanisms, are yet to be fully characterised. METHODS: In the current report, we employed NOD mice as a model to dissect the impact of blocking HMGB1 on the prevention, treatment and reversal of type 1 diabetes. To study the mechanism involved, we extensively examined the characteristics of regulatory T cells (Tregs) and their related signalling pathways upon HMGB1 stimulation. Furthermore, we investigated the relevance of our data to human autoimmune diabetes. RESULTS: Neutralising HMGB1 both delayed diabetes onset and, of particular relevance, reversed diabetes in 13 out of 20 new-onset diabetic NOD mice. Consistently, blockade of HMGB1 prevented islet isografts from autoimmune attack in diabetic NOD mice. Using transgenic reporter mice that carry a Foxp3 lineage reporter construct, we found that administration of HMGB1 impairs Treg stability and function. Mechanistic studies revealed that HMGB1 activates receptor for AGE (RAGE) and toll-like receptor (TLR)4 to enhance phosphatidylinositol 3-kinase (PI3K)-Akt-mechanistic target of rapamycin (mTOR) signalling, thereby impairing Treg stability and functionality. Indeed, high circulating levels of HMGB1 in human participants with type 1 diabetes contribute to Treg instability, suggesting that blockade of HMGB1 could be an effective therapy against type 1 diabetes in clinical settings. CONCLUSIONS/INTERPRETATION: The present data support the possibility that HMGB1 could be a viable therapeutic target to prevent the initiation, progression and recurrence of autoimmunity in the setting of type 1 diabetes.

Obesity predisposes to the risk of higher mortality in young COVID-19 patients.

Although emerging data demonstrated mortality of young COVID-19 patients, no data have reported the risk factors of mortality for these young patients, and whether obesity is a risk for young COVID-19 patients remains unknown. We conducted a retrospective study including 13 young patients who died of COVID-19 and 40 matched survivors. Logistic regression was employed to characterize the risk factors of mortality in young obese COVID-19 patients. Most of the young deceased COVID-19 patients were mild cases at the time of admission, but the disease progressed rapidly featured by a higher severity of patchy shadows (100.00% vs 48.70%; P = .006), pleural thickening (61.50% vs 12.80%; P = .012), and mild pericardial effusion (76.90% vs 0.00%; P < .001). Most importantly, the deceased patients manifested higher body mass index (odds ratio [OR] = 1.354; 95% confidence interval [CI] = 1.075-1.704; P = .010), inflammation-related index C-reactive protein (OR = 1.014; 95% CI = 1.003-1.025; P = .014), cardiac injury biomarker hs-cTnI (OR = 1.420; 95% CI = 1.112-1.814; P = .005), and increased coagulation activity biomarker D-dimer (OR = 418.7; P = .047), as compared with that of survivors. Our data support that obesity could be a risk factor associated with high mortality in young COVID-19 patients, whereas aggravated inflammatory response, enhanced cardiac injury, and increased coagulation activity are likely to be the mechanisms contributing to the high mortality.

Analysis of 2019 novel coronavirus infection and clinical characteristics of outpatients: An epidemiological study from a fever clinic in Wuhan, China.

BACKGROUND: Since the outbreak of 2019 novel coronavirus (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]) pneumonia, thousands of patients with fever or cough were flocked into fever clinic of designated hospitals in Wuhan, China. To date, no data have ever been reported to reflect the prevalence of coronavirus disease 2019 (COVID-19) among these outpatients. Moreover, it is almost unknown to discriminate COVID-19 and nucleic acid negative patients based on clinical features in the fever clinics. METHODS: The infectious status of SARS-CoV-2 was estimated among the outpatients. The epidemiological and clinical characteristics were compared between COVID-19 and nucleic acid negative patients. RESULTS: The nucleic acid positive rate for SARS-CoV-2 in the outpatients from our fever clinic was 67·1%, while the majority of patients with COVID-19 were mild cases. The predominant initial symptom in those patients with COVID-19 was fever (78.2%), followed by cough (15.6%). Very significantly lower number of eosinophils was characterized in patients with COVID-19 as compared with that of nucleic acid negative patients. More importantly, the proportion of subjects with eosinophil counts lower than normal levels in patients with COVID-19 was much higher than that of nucleic acid negative patients. Fever combined with bilateral ground-glass opacities in computed tomography imaging and eosinophil count below the normal level are probably a valuable indicator of COVID-19 infection in those outpatients. CONCLUSIONS: Those findings may provide critical information for the regions, such as Europe and United States that are facing the same situation as Wuhan experienced, and could be valuable to prevent those nucleic acid negative patients from misdiagnosis before antibody testing.

Cigarette smoke extract stimulates bronchial epithelial cells to undergo a SUMOylation turnover.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) characterized by the airway and lung inflammation, is a leading cause of morbidity and mortality worldwide, especially among smokers over 40 years of age and individuals exposed to biomass smoke. Although the detailed mechanisms of this disease remain elusive, there is feasible evidence that protein posttranslational modifications (PTMs) may play a role in its pathoetiology. We thus conducted studies to dissect the effect of cigarette smoke extracts (CSE) on the change of SUMOylated substrates in human bronchial epithelial cells (HBEs). METHODS: Samples were collected in HBEs with or without 24 h of CSE insult and then subjected to Western-blot and LC-MS/MS analysis. Subsequently, bioinformatic tools were used to analyze the data. The effect of SUMOylation on cytochrome P450 1A1 (CYP1A1) was evaluated by flow cytometry. RESULTS: It was noted that CSE stimulated HBEs to undergo a SUMOylation turnover as evidenced by the changes of SUMOylated substrates and SUMOylation levels for a particular substrate. The SUMOylated proteins are relevant to the regulation of biological processes, molecular function and cellular components. Particularly, CSE stimulated a significant increase of SUMOylated CYP1A1, a critical enzyme involved in the induction of oxidative stress. CONCLUSIONS: Our data provide a protein SUMOylation profile for better understanding of the mechanisms underlying COPD and support that smoking induces oxidative stress in HBEs, which may predispose to the development of COPD in clinical settings.

Both conditional ablation and overexpression of E2 SUMO-conjugating enzyme (UBC9) in mouse pancreatic beta cells result in impaired beta cell function.

AIMS/HYPOTHESIS: Post-translational attachment of a small ubiquitin-like modifier (SUMO) to the lysine (K) residue(s) of target proteins (SUMOylation) is an evolutionary conserved regulatory mechanism. This modification has previously been demonstrated to be implicated in the control of a remarkably versatile regulatory mechanism of cellular processes. However, the exact regulatory role and biological actions of the E2 SUMO-conjugating enzyme (UBC9)-mediated SUMOylation function in pancreatic beta cells has remained elusive. METHODS: Inducible beta cell-specific Ubc9 (also known as Ube2i) knockout (KO; Ubc9Δbeta) and transgenic (Ubc9Tg) mice were employed to address the impact of SUMOylation on beta cell viability and functionality. Ubc9 deficiency or overexpression was induced at 8 weeks of age using tamoxifen. To study the mechanism involved, we closely examined the regulation of the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) through SUMOylation in beta cells. RESULTS: Upon induction of Ubc9 deficiency, Ubc9Δbeta islets exhibited a 3.5-fold higher accumulation of reactive oxygen species (ROS) than Ubc9f/f control islets. Islets from Ubc9Δbeta mice also had decreased insulin content and loss of beta cell mass after tamoxifen treatment. Specifically, at day 45 after Ubc9 deletion only 40% of beta cell mass remained in Ubc9Δbeta mice, while 90% of beta cell mass was lost by day 75. Diabetes onset was noted in some Ubc9Δbeta mice 8 weeks after induction of Ubc9 deficiency and all mice developed diabetes by 10 weeks following tamoxifen treatment. In contrast, Ubc9Tg beta cells displayed an increased antioxidant ability but impaired insulin secretion. Unlike Ubc9Δbeta mice, which spontaneously developed diabetes, Ubc9Tg mice preserved normal non-fasting blood glucose levels without developing diabetes. It was noted that SUMOylation of NRF2 promoted its nuclear expression along with enhanced transcriptional activity, thereby preventing ROS accumulation in beta cells. CONCLUSIONS/INTERPRETATION: SUMOylation function is required to protect against oxidative stress in beta cells; this mechanism is, at least in part, carried out by the regulation of NRF2 activity to enhance ROS detoxification. Homeostatic SUMOylation is also likely to be essential for maintaining beta cell functionality.

Macrophages Regulate Unilateral Ureteral Obstruction-Induced Renal Lymphangiogenesis through C-C Motif Chemokine Receptor 2-Dependent Phosphatidylinositol 3-Kinase-AKT-Mechanistic Target of Rapamycin Signaling and Hypoxia-Inducible Factor-1α/Vascular Endothelial Growth Factor-C Expression.

Lymphangiogenesis occurs during renal fibrosis in patients with chronic kidney diseases and vascular endothelial growth factor (VEGF)-C is required for the formation of lymphatic vessels; however, the underlying mechanisms remain unclear. We demonstrate that macrophages can regulate unilateral ureteral obstruction (UUO)-induced renal lymphangiogenesis by expressing high levels of VEGF-C by C-C motif chemokine receptor 2 (CCR2)-mediated signaling. Mice deficient in Ccr2 manifested repressed lymphangiogenesis along with attenuated renal injury and fibrosis after UUO induction. The infiltrated macrophages after UUO induction generated a microenvironment in favor of lymphangiogenesis, which likely depended on Ccr2 expression. Mechanistic studies revealed that CCR2 is required for macrophages to activate phosphatidylinositol 3-kinase (PI3K)-AKT-mechanistic target of rapamycin (mTOR) signaling in response to its ligand monocyte chemoattractant protein 1 stimulation, whereas hypoxia-inducible factor (HIF)-1α is downstream of PI3K-AKT-mTOR signaling. HIF-1α directly bound to the VEGF-C promoter to drive its expression to enhance lymphangiogenesis. Collectively, we characterized a novel regulatory network in macrophages, in which CCR2 activates PI3K-AKT-mTOR signaling to mediate HIF-1α expression, which then drives VEGF-C expression to promote lymphangiogenesis.

Macrophages: friend or foe in idiopathic pulmonary fibrosis?

Idiopathic pulmonary fibrosis (IPF) is a prototype of lethal, chronic, progressive interstitial lung disease of unknown etiology. Over the past decade, macrophage has been recognized to play a significant role in IPF pathogenesis. Depending on the local microenvironments, macrophages can be polarized to either classically activated (M1) or alternatively activated (M2) phenotypes. In general, M1 macrophages are responsible for wound healing after alveolar epithelial injury, while M2 macrophages are designated to resolve wound healing processes or terminate inflammatory responses in the lung. IPF is a pathological consequence resulted from altered wound healing in response to persistent lung injury. In this review, we intend to summarize the current state of knowledge regarding the process of macrophage polarization and its mediators in the pathogenesis of pulmonary fibrosis. Our goal is to update the understanding of the mechanisms underlying the initiation and progression of IPF, and by which, we expect to provide help for developing effective therapeutic strategies in clinical settings.

Role of C/EBP homologous protein and endoplasmic reticulum stress in asthma exacerbation by regulating the IL-4/signal transducer and activator of transcription 6/transcription factor EC/IL-4 receptor α positive feedback loop in M2 macrophages.

BACKGROUND: C/EBP homologous protein (Chop), a marker of endoplasmic reticulum (ER) stress, exhibits aberrant expression patterns during asthma development. However, its exact role in asthma pathogenesis is not fully understood. OBJECTIVES: We aimed to determine the function and mechanism of Chop in the pathogenesis of allergic asthma in patients and animals. METHODS: Studies were conducted in asthmatic patients and Chop-/- mice to dissect the role of Chop and ER stress in asthma pathogenesis. An ovalbumin (OVA)-induced allergic airway inflammation model was used to address the effect of Chop deficiency on asthma development. Next, the effect of Chop deficiency on macrophage polarization and related signaling pathways was investigated to demonstrate the underlying mechanisms. RESULTS: Asthmatic patients and mice after OVA induction exhibited aberrant Chop expression along with ER stress. Specifically, Chop was noted to be specifically overexpressed in macrophages, and mice deficient in Chop were protected from OVA-induced allergic airway inflammation, as manifested by attenuated airway inflammation, remodeling, and hyperresponsiveness. Chop was found to exacerbate allergic airway inflammation by enhancing M2 programming in macrophages. Mechanistic studies characterized an IL-4/signal transducer and activator of transcription 6/transcription factor EC (Tfec)/IL-4 receptor α positive feedback regulatory loop, in which IL-4 induces Chop expression, which then promotes signal transducer and activator of transcription 6 signaling to transcribe Tfec expression. Finally, Tfec transcribes IL-4 receptor α expression to promote M2 programming in macrophages. CONCLUSIONS: Chop and ER stress are implicated in asthma pathogenesis, which involves regulation of M2 programming in macrophages.

Altered connexin 43 expression underlies age-dependent decrease of regulatory T cell suppressor function in nonobese diabetic mice.

Type 1 diabetes is one of the most extensively studied autoimmune diseases, but the cellular and molecular mechanisms leading to T cell-mediated destruction of insulin-producing ß cells are still not well understood. In this study, we show that regulatory T cells (T(regs)) in NOD mice undergo age-dependent loss of suppressor functions exacerbated by the decreased ability of activated effector T cells to upregulate Foxp3 and generate T(regs) in the peripheral organs. This age-dependent loss is associated with reduced intercellular communication mediated by gap junctions, which is caused by impaired upregulation and decreased expression of connexin 43. Regulatory functions can be corrected, even in T cells isolated from aged, diabetic mice, by a synergistic activity of retinoic acid, TGF-ß, and IL-2, which enhance connexin 43 and Foxp3 expression in T(regs) and restore the ability of conventional CD4(+) T cells to upregulate Foxp3 and generate peripherally derived T(regs). Moreover, we demonstrate that suppression mediated by T(regs) from diabetic mice is enhanced by a novel reagent, which facilitates gap junction aggregation. In summary, our report identifies gap junction-mediated intercellular communication as an important component of the T(reg) suppression mechanism compromised in NOD mice and suggests how T(reg) mediated immune regulation can be improved.