Non-Antigenic Modulation of Antigen Receptor (TCR) Cß-FG Loop Modulates Signalling: Implications of External Factors Influencing T-Cell Responses.

T-cell recognition of antigens is complex, leading to biochemical and cellular events that impart both specific and targeted immune responses. The end result is an array of cytokines that facilitate the direction and intensity of the immune reaction-such as T-cell proliferation, differentiation, macrophage activation, and B-cell isotype switching-all of which may be necessary and appropriate to eliminate the antigen and induce adaptive immunity. Using in silico docking to identify small molecules that putatively bind to the T-cell Cß-FG loop, we have shown in vitro using an antigen presentation assay that T-cell signalling is altered. The idea of modulating T-cell signalling independently of antigens by directly targeting the FG loop is novel and warrants further study.

Anti-inflammatory Effects of First-line Anti-arthritic Drugs on T-cell Activation.

AIM: The in vitro effects of commonly used first-line anti-arthritic drugs on early stages of T-cell activation were examined. METHODS: The 2B4.11 murine T cell hybridoma cell line recognizing pigeon cytochrome c (PCC) as the antigen was co-cultured with the histocompatible antigen presenting B cell hybridoma line LK35.2, PCC, and anti-arthritic drugs, including methotrexate, hydroxychloroquine, salazopyrine, cyclosporin, and leflunomide. After 16 hours of incubation, the supernatant was removed, and cytokines were assayed. RESULTS: Anti-arthritic drugs inhibited the production of pro-inflammatory cytokines IL-2, IL-6, IFN-γ, GM-CSF, and TNF-α (Th1 cytokines) to a varying extent. Surprisingly, leflunomide, salazopyrine, prednisone and indomethacin as well as blocking Th1 cytokines, stimulated the production of the anti-inflammatory cytokine IL-10, a Th2 cytokine. CONCLUSION: Anti-arthritic medications can inhibit the production of pro-inflammatory cytokines and in some cases, incite a Th2 response that could potentially inhibit the progression of the immune response.

The PI3K/Akt1-FoxO1 Translocation Pathway Mediates EXf Effects on NIT-1 Cell Survival.

EXf, a glucagon-like peptide 1 (GLP-1) receptor agonist, stimulates ß-cell proliferation and reduces apoptosis in diabetic animal models, but the underlying mechanisms are not fully understood. We constructed a FoxO1-GFP fusion protein expression plasmid and transiently transfected it into NIT-1 cells to investigate whether FoxO1 mediates EXf effects on NIT-1 cell survival. Our results showed that EXf could increase cell viability by inhibiting apoptosis and stimulating proliferation, and it could also promote the translocation of the FoxO1-GFP fusion protein from the nucleus to the cytoplasm in NIT-1 cells. However, the above effects of EXf were suppressed by the inhibitor of PI3K. Comparative transcription analysis showed up-regulation of igf-1r, irs-2, pI3k, akt1 and pdx-1 in NIT-1 cells after EXf treatment. Moreover, the up-regulation of PI3K and phosphorylation of Akt1 upon EXf treatment was confirmed by Western blot, both phenomena were abrogated by wortmannin, an inhibitor of PI3K. In summary, FoxO1 may mediate the effects of EXf on NIT-1 cell survival by activating the PI3K/Akt1 pathway.

A Human Glucagon-Like Peptide-1-albumin Recombinant Protein with Prolonged Hypoglycemic Effect Provides Efficient and Beneficial Control of Glucose Metabolism in Diabetic Mice.

GW002 is a recombinant protein engineered by fusing the C-terminal region of human glucagon-like peptide-1 (GLP-1) to the N-terminal region of human serum albumin (HSA) with a peptide linker. This study aims to evaluate its anti-diabetic effects both in vitro and in vivo. The GLP-1 receptor-dependent luciferase reporter plasmid was transiently transfected in NIT-1 cells to calculate the half-maximal concentration (EC50) for GLP-1 receptor activation, and normal ICR mice and diabetic KKAy mice were acutely injected with GW002 (1, 3, 9 mg/kg) subcutaneously to evaluate the hypoglycemic action, while the diabetic KKAy and db/db mice were treated with GW002 once daily for 7 weeks to evaluate the effects on glucose metabolism. The results showed that GW002 activated GLP-1 receptor in NIT-1 cells with higher EC50 versus exendin-4 (46.7 vs. 7.89 nM), and single subcutaneous injection of GW002 at doses of 1, 3 and 9 mg/kg efficiently restrained the glycemia variation after oral glucose loading in ICR mice for at least 4 d, as well as reducing the non-fasting blood glucose in KKAy mice for about 2 d, while repeated injections of GW002 significantly improved abnormal glycaemia, hemoglobin (Hb)A1c levels, oral glucose intolerance and ß-cell function in diabetic db/db mice. These results suggested that GW002 showed prolonged hypoglycemic action by activating its cognate receptor and provided efficient control of glucose metabolism. Thus GW002 may be a potential treatment for the management of type 2 diabetes.

Bis(α-furancarboxylato)oxovanadium(IV) exerts durable antidiabetic effects and suppresses matrix metalloproteinase-2 activity in spontaneous type 2 diabetic KKAy mice.

Vanadium compounds maintain euglycemic effects in diabetic rats long after drug withdrawal and bis(α-furancarboxylato)oxovanadium(IV) (BFOV) possesses potent antidiabetic effects in diabetic rats. Here, we investigated the treatment and posttreatment effects of BFOV in diabetic Kuo Kondo [1, 2] with Ay gene (KKAy) mice, and whether these effects were associated with changes in matrix metalloproteinases (MMPs). KKAy mice received normal saline or BFOV initially at 70 µmol/kg/day for 1 month, which was tapered to 17 µmol/kg/day in the next 2 months and discontinued thereafter. Compared to diabetic controls, fasting plasma glucose (FPG) was reduced by 46 and 19 % in KKAy mice after 70 µmol/kg BFOV for 1 month and 3 months after BFOV withdrawal, respectively. OGTT and ITT showed improved glucose tolerance and a better response of FPG to insulin with a significant decrease in HOMA-IR and a marked rise in the insulin sensitivity index after 70 µmol/kg BFOV for 1 month and 4 months after BFOV withdrawal (P <0.05 in all vs. diabetic controls). BFOV treatment resulted in a moderate but significant reduction in body weight and systolic blood pressure (SBP) at 1 month of treatment and 4 months following BFOV withdrawal (P <0.05 in all vs. diabetic controls). Gelatin zymography showed that serum MMP2 activity was significantly reduced and immunoblotting assays further showed that MMP2 expression was markedly downregulated in the liver after 1 month of treatment with 70 µmol/kg and 4 months after BFOV withdrawal (P <0.05 in all vs. diabetic controls). These results suggested that BFOV possessed potent treatment and posttreatment effects in KKAy mice with improved metabolic profile and reduced body weight and SBP. Furthermore, these effects were associated with decreased MMP2 expression and activity in diabetic KKAy mice.

Long-term treatment with EXf, a peptide analog of Exendin-4, improves ß-cell function and survival in diabetic KKAy mice.

EXf is a C-terminally truncated fragment of Exendin-4 with two amino acid substitutions. Previous studies showed that EXf controls plasma glucose level acting as a glucagon-like peptide 1 (GLP-1) receptor agonist. The purpose of this study was to evaluate the effects of EXf on ß-cell function and survival in diabetic KKAy mice. EXf treatment significantly improved the glucose intolerance and reduced non-fasting and fasting plasma glucose levels, as well as plasma triglyceride levels in diabetic KKAy mice. In hyperglycemic clamp test, EXf-treated mice displayed an increased glucose infusion rate and first-phase insulin secretion. Treatment with EXf also led to a significant restoration of islet morphology, an increase in Ki67 expression in ß-cells, and a reduction in the number of TUNEL positive ß-cells. In the pancreas, comparative transcription analysis showed up-regulation of Akt1. The up-regulation of phosphorylated Akt1 was confirmed by Western blot, and changes in the protein levels of members of the Akt1 pathway, such as PI3K, Bim, Bcl-2, Bax, Caspase-3, and Caspase-9, PDX-1, were observed as well. Therefore, EXf treatment could improve ß-cell function and survival in diabetic KKAy mice, likely as a result of islet morphology restoration, stimulation of ß-cell proliferation, and inhibition of ß-cell apoptosis.