A missense C1858T single nucleotide polymorphism in the PTPN22 gene recently emerged as a major risk factor for human autoimmunity. PTPN22 encodes the lymphoid tyrosine phosphatase (LYP), which forms a complex with the kinase Csk and is a critical negative regulator of signaling through the T cell receptor. The C1858T single nucleotide polymorphism results in the LYP-R620W variation within the LYP-Csk interaction motif. LYP-W620 exhibits a greatly reduced interaction with Csk and is a gain-of-function inhibitor of signaling. Here we show that LYP constitutively interacts with its substrate Lck in a Csk-dependent manner. T cell receptor-induced phosphorylation of LYP by Lck on an inhibitory tyrosine residue releases tonic inhibition of signaling by LYP. The R620W variation disrupts the interaction between Lck and LYP, leading to reduced phosphorylation of LYP, which ultimately contributes to gainof-function inhibition of T cell signaling.

OBJECTIVEThe Pediatric Artificial Pancreas (PedArPan) project tested a children-specific version of the modular model predictive control (MMPC) algorithm in 5-to 9-yearold children during a camp. RESEARCH DESIGN AND METHODSA total of 30 children, 5-to 9-years old, with type 1 diabetes completed an outpatient, open-label, randomized, crossover trial. Three days with an artificial pancreas (AP) were compared with three days of parent-managed sensoraugmented pump (SAP). RESULTSOvernight time-in-hypoglycemia was reduced with the AP versus SAP, median (25 th -75 th percentiles): 0.0% (0.0-2.2) vs. 2.2% (0.0-12.3) (P 5 0.002), without a significant change of time-in-target, mean: 56.0% (SD 22.5) vs. 59.7% (21.2) (P 5 0.430), but with increased mean glucose 173 mg/dL (36) vs. 150 mg/dL (39) (P 5 0.002). Overall, the AP granted a threefold reduction of time-in-hypoglycemia (P < 0.001) at the cost of decreased time-in-target, 56.8% (13.5) vs. 63.1% (11.0) (P 5 0.022) and increased mean glucose 169 mg/dL (23) vs. 147 mg/dL (23) (P < 0.001). CONCLUSIONSThis trial, the first outpatient single-hormone AP trial in a population of this age, shows feasibility and safety of MMPC in young children. Algorithm retuning will be performed to improve efficacy.Only three artificial pancreas (AP) trials have focused on the prepubertal population so far: two single-hormone AP studies, performed inpatient for less than 1 day (1,2) and a recent dual-hormone AP study, performed in a camp for 5 days (3). Here we report the first outpatient single-hormone AP trial focusing on 5-to 9-year-old children.Data were collected in the Pediatric Artificial Pancreas (PedArPan) camp, where sensor-augmented pump (SAP) therapy was compared with the modular model predictive control algorithm (MMPC) (4,5), running on the wearable platform Diabetes Assistant (DiAs) (6).

Activation of T cells is largely mediated through signal transduction downstream from the T-cell receptor (TCR) expressed on the cell surface. The TCR is a transmembrane receptor complex comprised of a and b chains, which bind ligands, and CD3 (e, c and d) and f chains containing motifs that are phosphorylated on tyrosine, called immunoreceptor tyrosine-based activation motifs. Signal transduction through the TCR is initiated when the receptor binds to a peptide-MHC complex presented by an antigen-presenting cell. This interaction initiates a cascade of signalling events, which induces the proliferation, mobilization and differentiation of T cells. For an updated and comprehensive review of signalling through the TCR the reader is referred to recent authoritative publications. [1][2][3][4] A dynamic wave of tyrosine phosphorylation phenomena is critical for ignition of intracellular signalling in T cells. Engagement of the TCR leads to the activation of the Src family protein tyrosine kinases (PTKs) LCK and FYN, which phosphorylate the immunoreceptor tyrosinebased activation motifs of the TCR. This provides docking sites for the SH2 domains of ZAP-70, a Syk family PTK, allowing ZAP-70 to be phosphorylated and activated by LCK. Once activated, ZAP-70 phosphorylates the adaptor proteins SLP-76 and LAT, which nucleate signalling complexes, leading to the phosphorylation and activation of multiple downstream effectors. This results in calcium mobilization, activation of mitogen-activated protein kinases (MAPKs), transcriptional regulation and cytoskeletal rearrangements.Protein tyrosine phosphatases (PTPs) are the natural counterpart of PTKs. Much like PTKs, depending upon the phosphorylation site and the signalling context, they can enhance or reduce the function of their protein target(s). The modern view of phosphorylation networks is one of dynamic 'always-on' grids where the stoichiometry of each phosphorylation site is continuously controlled by the changing balance between the activities of kinases and phosphatases. For example, the activation state of the Src family kinases (SFKs) is balanced between the activities of CSK and CD45, which respectively phosphorylate and dephosphorylate the inhibitory C-terminal site (Y505 of LCK), and the negative regulators LYP and SHP-1, which dephosphorylate an activating tyrosine in the catalytic domain (Y394 of LCK). Acute changes in PTP activity/ expression are in principle sufficient to alter the network status and even trigger true signalling waves. The recent 'kinetic-segregation' model postulates that PTPs are responsible for the very initiation of signalling after engagement of the TCR. SummaryMore than half of the known protein tyrosine phosphatases (PTPs) in the human genome are expressed in T cells, and significant progress has been made in elucidating the biology of these enzymes in T-cell development and function. Here we provide a systematic review of the current understanding of the roles of PTPs in T-cell activation, providing insight into their mechanisms ...

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Introduction: Management of Type 1 Diabetes (T1D) poses numerous challenges, especially for young children and their families. Parental care positively influences the outcomes of children with T1D, while there are often criticisms in school environment. The COVID-19 pandemic has forced children and parents to spend many hours at home and diabetes care has returned mainly in the hands of parents. Aim of the study: To evaluate the effectiveness of exclusive return to parental care in preschool and school children with T1D treated with Tandem Basal IQ system during the COVID-19 pandemic. Patients and methods: 22 children (M:F = 14:8) with T1D have been evaluated. We compared insulin and CGM data (TIR, TBR and TAR) of two periods: PRE-COV and IN-COV, in which children have transitioned from normal school attendance to the exclusive care of their parents.Results: During the IN-COV period a significantly (p < 0.001) higher median value of TIR (66,41%) was observed as compared to PRE-COV period (61,45%). Patients also showed a statistically significant difference (p < 0.002) between the IN-COV period and the PRE-COV period as concerning the TAR metric: respectively 29,86 ± 10,6% vs 34,73 ± 12,8%. The difference between the bolus insulin doses was statistically significant (PRE-COV 5,3 IU/day, IN-COV 7,9 IU/day -p < 0.05). Conclusion:Our observational real-life study confirms the positive effect of parental care in T1D very young children and demonstrates that during the COVID-19 pandemic it was possible to obtain a good glycometabolic compensation despite the significant change in lifestyle.

Recent evidence regarding the role of regulatory T cells (Treg) in tumor development has suggested that the manipulation of Treg function selectively in the tumor microenvironment would be a desirable immunotherapy approach. Targeting intratumor immune populations would reduce side effects on peripheral healthy cells and increase antitumor efficacy of immunotherapies. However, no current approaches are available which enable selective in vivo targeting of intratumor Treg or other immune cell subpopulations. Herein, we investigated the ability of ligands against Treg-specific receptors to drive selective internalization of PEG-modified single-walled carbon nanotubes (PEG-SWCNTs) into Treg residing in the tumor microenvironment. We focused our attention on the glucocorticoid-induced TNFR-related receptor (GITR), as it showed higher overexpression on intratumor vs peripheral (i.e., splenic) Treg compared to other reported Treg-specific markers (folate receptor 4, CD103, and CD39). Ex vivo investigations showed that the Treg targeting efficiency and selectivity of PEG-SWCNTs depended on incubation time, dose, number of ligands per nanotube, and targeted surface marker. In vivo investigations showed that PEG-SWCNTs armed with GITR ligands targeted Treg residing in a B16 melanoma more efficiently then intratumor non-Treg or splenic Treg. The latter result was achieved by exploiting a combination of passive tumor targeting due to enhanced tumor vascular permeability, naturally increased intratumor Treg vs effector T cell (Teff) ratio, and active targeting of markers that are enriched in intratumor vs splenic Treg. We also found that PEG-SWCNTs loaded with GITR ligands were internalized by Treg through receptor-mediated endocytosis and transported into the cytoplasm and nucleus ex vivo and in vivo. This is the first example of intratumor immune cell targeting and we hope it will pave the way to innovative immunotherapies against cancer.

The missense PTPN22 C1858T polymorphism recently emerged as an important population-independent risk factor for type 1 diabetes (T1D) and other autoimmune diseases. The PTPN22 gene encodes the lymphoid tyrosine phosphatase (LYP), a negative regulator of signal transduction through the T-cell receptor. Although the frequency of the polymorphism is variable among different ethnic groups, the association between PTPN22 *T1858 and T1D has been replicated in several populations. Here, we contribute the first replication of the association between PTPN22 and T1D in populations from continental Italy, carried out in two independent samples of T1D patients (N = 216 and 82) and controls (N = 271 and 89). Our data also suggest that T1D carriers of the *T1858 allele could be at increased risk for other comorbid autoimmune disorders.

Mycobacterium avium subspecies paratuberculosis (MAP) has been previously associated to T1D as a putative environmental agent triggering or accelerating the disease in Sardinian and Italian populations. Our aim was to investigate the role of MAP in T1D development by evaluating levels of antibodies directed against MAP epitopes and their human homologs corresponding to ZnT8 and proinsulin (PI) in 54 T1D at-risk children from mainland Italy and 42 healthy controls (HCs). A higher prevalence was detected for MAP/ZnT8 pairs (62,96% T1D vs. 7,14% HCs; p < 0.0001) compared to MAP/PI epitopes (22,22% T1D vs. 9,52% HCs) and decreasing trends were observed upon time-point analyses for most peptides. Similarly, classical ZnT8 Abs and GADA decreased in a time-dependent manner, whereas IAA titers increased by 12%. Responses in 0–9 year-old children were stronger than in 10–18 age group (75% vs. 69,1%; p < 0.04). Younger age, female sex and concomitant autoimmune disorders contributed to a stronger seroreactivity suggesting a possible implication of MAP in multiple autoimmune syndrome. Cross-reactivity of the homologous epitopes was reflected by a high correlation coefficient (r2 > 0.8) and a pairwise overlap of positivity (>83% for MAP/ZnT8).