Altered Tim-1 and IL-10 Expression in Regulatory B Cell Subsets in Type 1 Diabetes.

Background: Type 1 diabetes (T1D) is an autoimmune disease with a complex aetiology. B cells play an important role in the pathogenesis of T1D. Regulatory B cells (Bregs) are a subset of B cells that produce and secrete the inhibitory factor interleukin-10 (IL-10), thereby exerting an anti-inflammatory effect. It was recently discovered that T-cell immunoglobulin mucin domain 1 (Tim-1) is essential for maintaining Bregs function related to immune tolerance. However, the detailed understanding of Tim-1+ Bregs and IL-10+ Bregs in T1D patients is lacking. This study aimed to characterize the profile of B cell subsets in T1D patients compared with that in controls and determine whether Tim-1+ Bregs and IL-10+ Bregs play roles in T1D. Materials and Methods: A total of 47 patients with T1D, 30 patients with type 2 diabetes (T2D) and 24 healthy controls were recruited in this study. Flow cytometry was used to measure the levels of different B cell subsets (including B cells, plasmablasts, and Bregs) in the peripheral blood. Radiobinding assays were performed to detect the antibody titres of T1D patients. In addition, the correlations between different B cell subsets and patient parameters were investigated. Results: Compared with healthy controls, differences in frequency of Tim-1+ Bregs were significantly decreased in patients with T1D (36.53 ± 6.51 vs. 42.25 ± 6.83, P=0.02*), and frequency of IL-10+ Bregs were lower than healthy controls (17.64 ± 7.21vs. 24.52 ± 11.69, P=0.009**), the frequency of total Bregs in PBMC was also decreased in patients with T1D (1.42 ± 0.53vs. 1.99 ± 0.93, P=0.002.**). We analyzed whether these alterations in B cells subsets were associated with clinical features. The frequencies of Tim-1+ Bregs and IL-10+ Bregs were negatively related to fasting blood glucose (FBG) (r=-0.25 and -0.22; P=0.01* and 0.03*, respectively). The frequencies of Tim-1+ Bregs and IL-10+ Bregs are positively correlated with fast C-peptide (FCP) (r=0.23 and 0.37; P=0.02* and 0.0001***, respectively). In addition, the frequency of IL-10+ Breg was also negatively related to glycosylated haemoglobin (HbA1c) (r=-0.20, P=0.04*). The frequencies of Tim-1+ Bregs, IL-10+ Bregs and Bregs in T2D patients were reduced, but no statistically significant difference was found between other groups. Interestingly, there was positive correlation between the frequencies of Tim-1+ Bregs and IL-10+ Bregs in T1D (r=0.37, P=0.01*). Of note, it is worth noting that our study did not observe any correlations between B cell subsets and autoantibody titres. Conclusions: Our study showed altered Tim-1 and IL-10 expression in regulatory B cell in T1D patients. Tim-1, as suggested by the present study, is associated with islet function and blood glucose levels. These findings indicate that Tim-1+ Bregs and IL-10+ Bregs were involved in the pathogenesis of T1D.

Extracellular Signal-Regulated Kinase 1/2 Regulates Mouse Kidney Injury Molecule-1 Expression Physiologically and Following Ischemic and Septic Renal Injury.

The upregulation of kidney injury molecule-1 (KIM-1) has been extensively studied in various renal diseases and following acute injury; however, the initial mechanisms controlling KIM-1 expression remain limited. In this study, KIM-1 expression was examined in mouse renal cell cultures and in two different models of acute kidney injury (AKI), ischemia reperfusion (IR)-induced and lipopolysaccharide (LPS)-induced sepsis. KIM-1 mRNA increased in both AKI models, and pharmacological inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) signaling attenuated injury-induced KIM-1 expression in the renal cortex. Toll-like receptor 4 knockout (TLR4KO) mice exhibited reduced ERK1/2 phosphorylation and attenuated KIM-1 mRNA after LPS exposure. TLR4KO mice were not protected from IR-induced ERK1/2 phosphorylation and upregulation of KIM-1 mRNA. Following renal IR injury, phosphorylation of signal transducer and activator of transcription 3 (STAT3) at serine 727 and tyrosine 705 increased downstream from ERK1/2 activation. Because phosphorylated STAT3 is a transcriptional upregulator of KIM-1 and inhibition of ERK1/2 attenuated increases in STAT3 phosphorylation, we suggest an ERK1/2-STAT3-KIM-1 pathway following renal injury. Finally, ERK1/2 inhibition in naive mice decreased KIM-1 mRNA and nuclear STAT3 phosphorylation in the cortex, indicating homeostatic regulation of KIM-1. These findings reveal renal ERK1/2 as an important initial regulator of KIM-1 expression in IR and septic AKI and at a physiologic level.Visual Abstract.Proposed mechanism of IR, LPS, and ROS-induced renal damage that initiates ERK1/2 and STAT3 phosphorylation. STAT3 then binds to the KIM-1 promoter and increases KIM-1 mRNA. By preventing ERK1/2 phosphorylation following renal injury, STAT3 phosphorylation is decreased, leading to less phosphorylated STAT3 within the nucleus, and subsequently less KIM-1 mRNA increases post injury.

TIM-1 defines a human regulatory B cell population that is altered in frequency and function in systemic sclerosis patients.

BACKGROUND: Systemic sclerosis (SSc) is a systemic autoimmune disease characterized by excessive production of extracellular matrix by fibroblasts on skin and internal organs. Although Th2 cells have been involved in fibroblast stimulation, hyperactivated B cells may also play an important role. Regulatory B cells (Bregs) are cells capable of inhibiting inflammatory responses and controlling autoimmune diseases. Although many Breg populations have in common the ability to produce high amounts of IL-10, a unique surface marker defining most human Bregs is lacking. It has been described in mice that T cell Ig and mucin domain protein 1 (TIM-1) is an inclusive marker for Bregs, and that TIM-1+ B cells are able to prevent the development of autoimmunity. The aim of this work was to evaluate TIM-1 as a marker for human IL-10+ Bregs, and to determine whether TIM-1+ B cells are defective in SSc patients. METHODS: SSc patients (n = 39) and 53 healthy subjects were recruited. TIM-1 and IL-10 expression was assessed in resting or activated peripheral blood CD19+ B cells by flow cytometry. The regulatory function of TIM-1+ or activated B cells from SSc patients and healthy subjects was assessed in autologous and allogenic co-cultures with CD4+ T cells, where T cell proliferation and IFN-γ, IL-17, TNF-α and IL-4 production by T cells was measured by flow cytometry. RESULTS: TIM-1 and IL-10 were preferentially expressed in transitional B cells, but were upregulated in naïve and memory B cells upon stimulation. The frequency of transitional TIM-1+ IL-10+ B cells was significantly decreased in SSc patients compared to healthy controls. In addition, activated B cells from SSc patients induced stronger allogenic Th1 and Th2 responses than activated B cells from healthy controls. Finally, TIM-1+ B cells, including transitional and non-transitional cells, exhibited a higher CD4+ T cell suppressive ability than TIM-1- B cells in healthy controls, but not in SSc patients. CONCLUSIONS: TIM-1 is a unique marker for the identification of a human IL-10+ Breg subpopulation which is partially superimposed with transitional B cells. Alterations in TIM-1+ B cells could contribute to the development of autoimmune diseases such as SSc.

Expression of Neutrophil Gelatinase-Associated Lipocalin and Kidney Injury Molecule-1 in Wilms Tumor.

OBJECTIVE: Neutrophil gelatinase-associated lipocalin (NGAL) and Kidney injury molecule-1 (KIM-1) play important roles in both immunity and cell proliferation. It was reported previously that they are overexpressed in various human cancers. The present study was undertaken to examine the expressions of NGAL and KIM-1 in Wilms Tumors. MATERIAL AND METHOD: Tissue samples of 50 Wilms Tumors were evaluated and underwent immunhistochemical staining for NGAL and KIM-1 protein expressions. The correlations between them, and some clinical prognostic factors such as tumor weight, stage and histological features were also evaluated. RESULTS: Twenty-three (46%) of the cases were male while 27 (54%) were female. The mean age was found to be 3.26±2 years. The average tumor size was 9.16 ± 2.9 cm in diameter and the average weight of the kidney was 478±312 gr. Thirteen (26%) cases were stage I, 18 (36%) cases were stage II, 7 (14%) cases were stage III, and 6 (12%) cases were stage IV. Thirty-nine cases were alive (78%), while 11 cases (22%) were deceased. Mean overall survival time was 68.2±39.5 (2-148) months. NGAL expression was negative in all tumors except the neutrophils within the tumors. KIM-1 expression was positive in 37 tumors (74%), while it was absent in 13 tumors (26%). Using Mann-Whitney U Analysis, KIM-1 expression was found to be associated with the stage of the tumor (p=0.027). CONCLUSION: The preliminary data indicates that KIM-1 expression may be associated with stage in Wilms Tumor. However, further studies are needed to validate these pilot observations and to clarify the functional and mechanistic significance of this relevance.

Andrographolide-induced apoptosis in human renal tubular epithelial cells: Roles of endoplasmic reticulum stress and inflammatory response.

Andrographolide sodium bisulfate as a kind of soluble derivative of andrographolide (AD), is obviously known to be nephrotoxicity, but AD has not been reported clearly. Our study aimed to investigate the induction of apoptosis in human renal tubular epithelial (HK-2) cells by AD and its possible mechanism. Our results demonstrated that AD (0-250µmol/L) inhibited Hk-2 cells proliferation in a dose- and time-dependent manner and induced apoptosis, accompanied by decreased of superoxide dismutase (SOD) activity and increased of malondialdehvde (MDA) content. Simultaneously, AD regulated the expression of endoplasmic reticulum (ER) molecular chaperone glucose-regulated protein 78 (GRP78/Bip) protein, elevated the expressions of C/EBP homologous protein (CHOP) and Caspase-4, indicating activation of ER stress signaling, and induced the alterative expression of kidney injury molecule-1 (KIM-1), tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6) proteins. It provided evidence that ER stress and inflammation would be significant mechanisms responsible for AD-induced apoptosis in addition to oxidative stress.