Suppression of Th1 cytokine production by a peptide derived from C4b

Altered kynurenine pathway metabolism and association with disease activity in patients with systemic lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease accompanied by increased release of proinflammatory cytokines that are known to activate the indoleamine 2,3-dioxygenase (IDO-1) enzyme, which catalyzes the rate-limiting step of the kynurenine pathway (KP). This study aimed to measure KP metabolite levels in patients with SLE and investigate the relationship between disease activity, clinical findings, and KP. The study included 100 patients with SLE and 100 healthy controls. Serum tryptophan (TRP), kynurenine (KYN), kynurenic acid (KYNA), 3-hydroxyanthranilic acid (3HAA), 3-hydroxykynurenine (3HK), quinolinic acid (QA) concentrations were measured with tandem mass spectrometry. Serum KYN, KYNA, 3HAA, 3HK, and QA levels of the patients with SLE were significantly higher than the control group. Serum QA levels were elevated in patients with neurological involvement (four patients with peripheral neuropathy and two patients with mononeuropathy), serum KYN levels and KYN/TRP ratio increased in patients with joint involvement, and serum KYN, 3HK, and 3HAA levels and the KYN/TRP ratio were increased in patients with renal involvement. Moreover, KYN and KYN/TRP ratios were positively correlated with the disease activity score. These findings indicated that imbalances in KP metabolites may be associated with the pathogenesis, activation, and clinical manifestations of SLE.

Physiological heating augments the anti-inflammatory reactions during granulocyte/monocyte apheresis: A in vitro study

Granulocyte and monocyte adsorptive apheresis (GMA), an effective therapy for inflammatory disorders, exerts an anti-inflammatory influence by utilizing the biological reaction between blood and cellulose acetate (CA) beads, which are the carriers of the GMA column. Although the biological reaction has an optimum temperature, blood contacts the CA beads below body temperature as GMA is performed in an extracorporeal circulation system. We investigated various soluble factors in blood treated with CA beads at 25°C and 37°C. Here, the optimal temperature for IL-1 receptor antagonist (IL-1ra) release induced by CA beads was 37°C, and IL-6 production from monocytic cells was inhibited by the addition of plasma prepared from the CA bead-treated blood at 37°C, rather than at 25°C. These results indicated that physiological heating of the apheresis carrier augmented the anti-inflammatory reaction in vitro. Thus, heating during GMA may be a new approach for augmenting clinical efficacy.

Apurinic/Apyrimidinic Endonuclease 1/Redox Factor-1 (Ape1/Ref-1) Modulates Antigen Presenting Cell-mediated T Helper Cell Type 1 Responses

Apurinic/apyrimidinic endonuclease 1/redox factor-1 (Ape1/Ref-1) is a multifunctional protein possessing DNA repair, redox control, and transcriptional regulatory activities. Although Ape1/Ref-1 plays multiple roles in the immune system, its functions in helper T (Th) cell activation and differentiation are largely unknown. In this study, the function of Ape1/Ref-1 in Th cell activation was analyzed using an Ape1/Ref-1 redox-specific inhibitor, E3330. When splenocytes from OT-II mice, which are ovalbumin (OVA)-specific T-cell receptor transgenic mice, were activated with OVA in the presence of E3330, the induction of IFN-γ-producing OT-II T cells was significantly increased. In contrast, E3330 did not enhance IFN-γ production from plate-bound anti-CD3 antibody-stimulated CD4⁺ T cells in the absence of antigen presenting cells (APCs). Furthermore, E3330-pretreated and OVA-pulsed APCs also enhanced the IFN-γ production from OT-II T cells. These results suggested that E3330 enhances Th1 responses by modifying APC function. E3330 did not alter the surface expression of MHC-II or the co-stimulatory molecules CD80 and CD86 on APCs. On the other hand, E3330 up-regulated the IL-12 p35 and p40 gene expression, and IL-12 surface retention, but decreased the IL-12 secretion from Toll-like receptor (TLR) ligand-stimulated APCs. These results were confirmed with Ape1/Ref-1 knockdown experiments. Taken together, our findings indicated that the suppression of Ape1/Ref-1 redox function leads to an increased cell surface retention of IL-12 and enhances Th1 responses. This is the first study to demonstrate that Ape1/Ref-1 modulates the IL-12 production and secretion from APCs and controls Th1 immune responses.

Complement C4 induces regulatory T cells differentiation through dendritic cell in systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease. Complement component 4 (C4) has be proved to play a role in pathogenesis of SLE. In the present study, we investigated the effect of C4 on T cells differentiation.

Methods

Thirty SLE patients were included in this study. CD4+ T cells were isolated from healthy subjects, and dendritic cells (DCs) were isolated from healthy subjects or SLE patients. C4 was supplemented to co-incubate with T cells and DCs.

Results

Serum C4 concentration was positively correlated with regulatory T cell (Treg) percentage (R² = 0.5907, p < 0.001) and TGFβ concentration (R² = 0.5641, p < 0.001) in SLE patients. Different concentrations of C4 had no effect on T cells differentiation. Co-incubated T cells with DCs and C4 for 7 days, the Treg percentage and TGF-β concentration were significantly elevated. In addition, pre-treated DCs (from healthy subjects or SLE patients) with C4 and then co-incubated with T cells, the increases of Treg percentage and TGF-β concentration were also observed.

Conclusion

C4 takes part in T cells differentiation to Treg cells via DCs.

Mesenchymal stem cells-regulated Treg cells suppress colitis-associated colorectal cancer

INTRODUCTION

Previous studies have produced controversial results regarding whether mesenchymal stem cells (MSCs) promote or inhibit tumor development. Given the dual role of MSCs in inflammation and cancer, in this study the colitis-associated colorectal cancer (CAC) model was used to examine whether umbilical cord tissue-derived MSCs could prevent neoplasm by inhibiting chronic inflammation.

METHODS

MSCs were obtained and identified using flow cytometry. Colitis-associated colorectal cancer model was induced using azoxymethane (AOM) and dextran sulfate sodium (DSS) and MSCs were injected intravenously twice. Levels of immune cells in mesenteric lymph node including regulatory T (Treg) cells were detected using flow cytometry. Naïve T cells and Jurkat cells were co-cultured with MSCs and the effect of MSCs on Treg cells differentiation was evaluated.

RESULTS

After injection through tail vein, MSCs could migrate to colon and suppress colitis-related neoplasm. This tumor suppressive effect was characterized by longer colon length, decreased tumor numbers and decreased expression of Ki-67. Moreover, MSCs alleviated the pathology of inflammation in the colitis stage of CAC model and inhibited inflammation cytokines both in colon and serum. Furthermore, Treg cells were accumulated in mesenteric lymph node of MSCs-treated mice while the percentage of T helper cells 2 (Th2) and Th17 were not changed. Of note, MSCs secreted transforming growth factor-β (TGF-β) enhanced the induction of Treg cells from naïve T cells. The conditioned medium of MSCs also activated Smad2 signaling, which has been reported to regulate Treg cells.

CONCLUSIONS

These results proved that MSCs could migrate to colon tissues and induce the differentiation of Treg cells via Smad2 as so to inhibit the colitis and suppress the development of CAC.