Search

AIMS: We examined the effect of growth hormone (GH) counter-regulation on carbohydrate metabolism in individuals with life-long diminished insulin secretion (DIS).METHODS: Adults homozygous for the E180 splice site mutation of GHR [Laron syndrome (LS)], adults with a gain-of-function mutation in CDKN1c [Guevara-Rosenbloom syndrome (GRS)], and controls were evaluated for body composition, leptin, total and high molecular weight (HMW) adiponectin, insulin-like growth factor (IGF) axis molecules, and a 5-hour oral glucose tolerance test (OGTT), with measurements of glucose, insulin, glucagon, ghrelin, pancreatic polypeptide, gastric inhibitory peptide, glucagon-like peptide-1, peptide YY, and islet amyloid polypeptide (IAPP).RESULTS: Both syndromic cohorts displayed DIS during OGTT. LS subjects had higher serum concentrations of total and HMW adiponectin, and lower levels of IGF-I, IGF-II, and IGF-Binding Protein-3 than individuals in other study groups. Furthermore, they displayed normal glycemic responses during OGTT with the lowest IAPP secretion. In contrast, individuals with GRS had higher levels of protein glycation, deficient glucose control during OGTT, and increased secretion of IAPP.CONCLUSIONS: A distinct metabolic phenotype depending on GH counter-regulatory status, associates with diabetes development and excess glucose-induced IAPP secretion.

Type 1 diabetes (T1D) presents with two therapeutic challenges: the need to correct underlying autoimmunity and restore β-cell mass. We harnessed the unique capacity of regulatory T cells (Tregs) and the T cell receptor (TCR) to direct tolerance induction along with tissue-localized delivery of therapeutic agents to restore endogenous β-cell function. Specifically, we designed a combinatorial therapy involving biomaterials-based poly(lactic-co-glycolic acid) nanoparticles co-loaded with the Treg growth factor, IL-2, and the β-cell regenerative agent, harmine (a tyrosine-regulated kinase 1A [DYRK1A] inhibitor), conjugated to the surface of Tregs. We observed continuous elution of IL-2 and harmine from nanoparticles for at least 7 days in vitro. When conjugated to primary human Tregs, IL-2 nanoparticles provided sufficient IL-2 receptor signaling to support STAT5 phosphorylation for sustained phenotypic stability and viability in culture. Inclusion of poly-L-lysine (PLL) during nanoparticle-cell coupling dramatically increased conjugation efficiency, providing sufficient IL-2 to support in vitro proliferation of IL-2-dependent CTLL-2 cells and primary murine Tregs. In 12-week-old female non-obese diabetic mice, adoptive transfer of IL-2/harmine nanoparticle-conjugated NOD.BDC2.5 Tregs, which express an islet antigen-specific TCR, significantly prevented diabetes demonstrating preserved in vivo viability. These data provide the preclinical basis to develop a biomaterials-optimized cellular therapy to restore immune tolerance and promote β-cell proliferation in T1D through receptor-targeted drug delivery within pancreatic islets.

Co-stimulation serves as a critical checkpoint for T cell development and activation, and several genetic variants affecting co-stimulatory pathways confer risk for autoimmune diseases. A single nucleotide polymorphism in CD226 (rs763361; G307S) has been shown to increase susceptibility to type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. CD226 competes with the co-inhibitory receptor TIGIT (T cell immunoreceptor with Ig and ITIM domains) to bind CD155 to amplify TCR signaling. We previously found that Cd226 knockout protected non-obese diabetic (NOD) mice from disease, but the impact of CD226 signaling on individual immune subsets remained unclear. We focused on regulatory T cells (Tregs) as a population of interest, as prior reports demonstrated that human CD226+ Tregs exhibit reduced FOXP3+Helios+ purity and suppressive function following expansion. Hence, we hypothesized that global deletion of Cd226 would increase Treg stability and accordingly, Treg-specific Cd226 deletion would inhibit diabetes in NOD mice. Indeed, crossing the NOD.Cd226-/- and NOD.Foxp3-GFP-Cre.R26-loxP-STOP-loxP-YFP Treg-fate tracking strains resulted in increased Treg induction and decreased FoxP3-deficient “ex-Tregs” in the pancreatic lymph nodes. We generated a Treg-conditional knockout (TregΔCd226) strain and found that female TregΔCd226 mice had decreased insulitis and diabetes incidence compared to TregWT mice. Additionally, we observed increased TIGIT expression on Tregs and conventional CD4+ T cells within the pancreas of TregΔCd226 versus TregWT mice. These findings demonstrate that an imbalance of CD226/TIGIT signaling may contribute to Treg destabilization in the NOD mouse and highlight the potential for therapeutic targeting of this pathway to prevent or reverse autoimmunity.

IL-2 has been proposed to restore tolerance via regulatory T cell (Treg) expansion in autoimmunity, yet off-target effects necessitate identification of a combinatorial approach. We recently reported reduced levels of immunoregulatory insulin-like growth factor-1 (IGF1) during type 1 diabetes (T1D) progression. Thus, we hypothesized that IGF1 would synergize with IL-2 to expand Tregs. We observed IGF1R was elevated on murine memory and human naïve Treg subsets. IL-2 and IGF1 promoted murine PI3K/Akt and human STAT5 signaling in Tregs. IL-2 and IGF1 treatment expanded Tregs beyond either agent alone in NOD mice. Incubation of naïve human CD4+T cells with IL-2 and IGF1 enhanced Treg proliferationin vitro, without the need for T cell receptor ligation. This synergism was attributed to increased high-affinity IL-2Rα expression on naïve Tregs, in contrast to intermediate-affinity IL-2Rβ and IL-2Rγ subunit enhancement on naïve conventional T cells (Tconv). We then demonstrated that IGF1 and IL-2 or the IL2Rγ-chain-dependent cytokine, IL-7, can be used to induce proliferation of genetically-engineered naïve Treg or Tconv cells, respectively. These data support the potential use of IGF1 in combination with common γ-chain cytokines to drive T cell expansions bothin vitroandin vivofor cellular therapeutics and genetic modifications.

Context We recently demonstrated increased cellular proliferation in the pancreatic ductal gland (PDG) compartment of organ donors with type 1 diabetes, suggesting that PDGs may harbor progenitor cells capable of pancreatic regeneration. Objective We evaluated the impact of diabetes and pancreatic inflammation on PDG and interlobular duct (ILD) cellular proliferation and profiles. Methods Endocrine hormone expression (insulin, glucagon, somatostatin, pancreatic polypeptide) and proliferating Ki67+ cells were localized within the PDG and ILD compartments by multicolor immunohistochemistry in cross-sections from the head, body, and tail regions of pancreata from those with (n = 31) or without type 1 diabetes (n = 43). Whole-slide scanned images were analyzed using digital pathology. Results Type 1 diabetes donors with insulitis or histologically identified pancreatitis had increased cellular replication in the ILD and PDG compartments. Interestingly, while cellular proliferation within the pancreatic ductal tree was significantly increased in type 1 diabetes (PDG mean = 3.36%, SEM = 1.06; ILD mean = 2.78%, SEM = 0.97) vs nondiabetes(ND) subjects without pancreatic inflammation (PDG mean = 1.18%, SEM = 0.42; ILD mean = 0.74%, SEM = 0.15, P Conclusion These data suggest that increased pancreatic ductal cell replication is associated with sustained pancreatic inflammation; however, as replicating cells were hormone-negative, PDGs do not appear to represent a compelling endogenous source of hormone-positive endocrine cells.

Women are broadly underrepresented in scientific leadership positions and their accomplishments are not provided equal recognition compared with those of men, but the imbalance in the field of diabetes is unknown. Hence, we analyzed multiple aspects of historical and present-day female representation in the diabetes field.We quantified gender representation at annual American Diabetes Association (ADA) meetings; editorial board service positions for ADA and the European Association for the Study of Diabetes (EASD) journals; principal investigators for ADA, JDRF, and National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases P30 grant funding; and ADA, JDRF, and EASD award recipients. There are many women in the field of diabetes: registration for the ADA Scientific Sessions has been 43% female since 2016, and for over five decades, women comprised 83% of ADA Presidents of Health Care and Education. Yet, only 9% of ADA Presidents of Medicine and Science have been women. Women were well represented on editorial boards for journals focused on diabetes education (Diabetes Spectrum, 89% female) and primary care (Clinical Diabetes, 49% female) but not for the more academically targeted Diabetes Care (34% female), Diabetes (21% female), and Diabetologia (30% female). Only one-third of ADA Pathway to Stop Diabetes and JDRF grants have been awarded to women, and females only lead 2 of 18 (11%) of the P30-supported Diabetes Research Centers. Finally, only 2-12% of major ADA, JDRF, and EASD awards were given to women, without significant change over time. Despite increasing recognition of gender imbalance in research and medicine, many disparities in the field of diabetes persist. We call for decreasing barriers for advancement of female investigators and creating environments that promote their retention and equitable recognition for their contributions to the field.

Regulatory T cell (Treg) adoptive cell therapy (ACT) represents an emerging strategy for restoring immune tolerance in autoimmune diseases. Tregs are commonly purified using a CD4