Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) plays a critical role in peripheral tolerance. However, regulatory pathways initiated by the interactions of CTLA-4 with B7 counterligands expressed on antigen-presenting cells are not completely understood. We show here that long-term survival of pancreatic islet allografts induced by the soluble fusion protein CTLA-4-immunoglobulin (CTLA-4-Ig) is contingent upon effective tryptophan catabolism in the host. In vitro, we show that CTLA-4-Ig regulates cytokine-dependent tryptophan catabolism in B7-expressing dendritic cells. These data suggest that modulation of tryptophan catabolism is a means by which CTLA-4 functions in vivo and that CTLA-4 acts as a ligand for B7 receptor molecules that transduce intracellular signals.
Orally administered VSL#3 prevents autoimmune diabetes and induces immunomodulation by a reduction in insulitis severity. Our results provide a sound rationale for future clinical trials of the primary prevention of type 1 diabetes by oral VSL#3 administration.
OBJECTIVETo compare the pharmacokinetics and pharmacodynamics of NPH, glargine, and detemir insulins in type 2 diabetic subjects.RESEARCH DESIGN AND METHODSThis study used a single-blind, three-way, cross-over design. A total of 18 type 2 diabetic subjects underwent a euglycemic clamp for 32 h after a subcutaneous injection of 0.4 units/kg at 2200 h of either NPH, glargine, or detemir after 1 week of bedtime treatment with each insulin.RESULTSThe glucose infusion rate area under the curve0–32 h was greater for glargine than for detemir and NPH (1,538 ± 688; 1,081 ± 785; and 1,170 ± 703 mg/kg, respectively; P < 0.05). Glargine suppressed endogenous glucose production more than detemir (P < 0.05) and similarly to NPH (P = 0.16). Glucagon, C-peptide, free fatty acids, and β-hydroxy-butyrate were more suppressed with glargine than detemir. All 18 subjects completed the glargine study, but two subjects on NPH and three on detemir interrupted the study because of plasma glucose >150 mg/dL.CONCLUSIONSCompared with NPH and detemir, glargine provided greater metabolic activity and superior glucose control for up to 32 h.
OBJECTIVE
This study characterized the pharmacokinetics (PK), pharmacodynamics (PD), and endogenous (hepatic) glucose production (EGP) of clinical doses of glargine U300 (Gla-300) and glargine U100 (Gla-100) under steady-state (SS) conditions in type 1 diabetes mellitus (T1DM).
RESEARCH DESIGN AND METHODS
T1DM subjects (N = 18, age 40 ± 12 years, T1DM duration 26 ± 12 years, BMI 23.4 ± 2 kg/m2, A1C 7.19 ± 0.52% [55 ± 5.7 mmol · mol−1−1]) were studied after 3 months of Gla-300 or Gla-100 (evening dosing) titrated to fasting euglycemia (random, crossover) with the euglycemic clamp using individualized doses (Gla-300 0.35 ± 0.08, Gla-100 0.28 ± 0.07 units · kg−1).
RESULTS
Plasma free insulin concentrations (free immunoreactive insulin area under the curve) were equivalent over 24 h with Gla-300 versus Gla-100 (point estimate 1.11 [90% CI 1.03; 1.20]) but were reduced in the first 6 h (0.91 [90% CI 0.86; 0.97]) and higher in the last 12 h postdosing (1.38 [90% CI 1.21; 1.56]). Gla-300 and Gla-100 both maintained 24 h euglycemia (0.99 [90% CI 0.98; 1.0]). The glucose infusion rate was equivalent over 24 h (1.03 [90% CI 0.88; 1.21]) but was lower in first (0.77 [90% CI 0.62; 0.95]) and higher (1.53 [90% CI 1.23; 1.92]) in the second 12 h with Gla-300 versus Gla-100. EGP was less suppressed during 0–6 h but more during 18–24 h with Gla-300. PK and PD within-day variability (fluctuation) was 50% and 17% lower with Gla-300.
CONCLUSIONS
Individualized, clinical doses of Gla-300 and Gla-100 resulted in a similar euglycemic potential under SS conditions. However, Gla-300 exhibited a more stable profile, with lower variability and more physiological modulation of EGP compared with Gla-100.
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