Avidity-dependent programming of autoreactive T cells in T1D.

Fate determination for autoreactive T cells relies on a series of avidity-dependent interactions during T cell selection, represented by two general types of signals, one based on antigen expression and density during T cell development, and one based on genes that interpret the avidity of TCR interaction to guide developmental outcome. We used proinsulin-specific HLA class II tetramers to purify and determine transcriptional signatures for autoreactive T cells under differential selection in type 1 diabetes (T1D), in which insulin (INS) genotypes consist of protective and susceptible alleles that regulate the level of proinsulin expression in the thymus. Upregulation of steroid nuclear receptor family 4A (NR4A) and early growth response family genes in proinsulin-specific T cells was observed in individuals with susceptible INS-VNTR genotypes, suggesting a mechanism for avidity-dependent fate determination of the T cell repertoire in T1D. The NR4A genes act as translators of TCR signal strength that guide central and peripheral T cell fate decisions through transcriptional modification. We propose that maintenance of an NR4A-guided program in low avidity autoreactive T cells in T1D reflects their prior developmental experience influenced by proinsulin expression, identifying a pathway permissive for autoimmunity

Avidity-Dependent Programming of Autoreactive T Cells in T1D

<div><p>Fate determination for autoreactive T cells relies on a series of avidity-dependent interactions during T cell selection, represented by two general types of signals, one based on antigen expression and density during T cell development, and one based on genes that interpret the avidity of TCR interaction to guide developmental outcome. We used proinsulin-specific HLA class II tetramers to purify and determine transcriptional signatures for autoreactive T cells under differential selection in type 1 diabetes (T1D), in which insulin <i>(INS)</i> genotypes consist of protective and susceptible alleles that regulate the level of proinsulin expression in the thymus. Upregulation of steroid nuclear receptor family 4A (NR4A) and early growth response family genes in proinsulin-specific T cells was observed in individuals with susceptible <i>INS</i>-VNTR genotypes, suggesting a mechanism for avidity-dependent fate determination of the T cell repertoire in T1D. The NR4A genes act as translators of TCR signal strength that guide central and peripheral T cell fate decisions through transcriptional modification. We propose that maintenance of an NR4A-guided program in low avidity autoreactive T cells in T1D reflects their prior developmental experience influenced by proinsulin expression, identifying a pathway permissive for autoimmunity.</p></div

Influence of INS genotype on expression profiles of proinsulin-specific CD4+ T cells.

<p>Relative expression profiles are shown for all subjects matched for HLA-DRB1*04:01 and selected for high antigen avidity using the proinsulin 76–90 tetramer <b>(A)</b>. Several genes showed significant transcript differences between control and T1D subjects matched for the INS VNTR III diabetes-protective genotype, all p<0.01. <b>(B)</b>.</p

Relative expression plots for significant genes that distinguish between healthy individuals and T1D patients.

<p>Patients with both INS genotypes (<b>A</b>), those with the VNTR I-susceptible INS genotype (<b>B</b>), and VNTR III-protective INS genotype (<b>C</b>) are shown. Horizontal lines indicate medians and inter-quartile ranges. The differences in the level of transcript-expression between healthy individuals and T1D patients were calculated using a Mann-Whitney U test. Only plots reaching significant difference between the groups are shown.</p

Flow cytometry profile of CD4+ T cells.

<p>A T1D patient with the susceptible INS VNTR I/I genotype is shown <b>(A)</b>. Staining with the proinsulin 76–90 tetramer (left) and the 88S tetramer (right) is shown. Influence of INS genotype on the frequency of proinsulin-specific CD4+ T cells <b>(B)</b>, shown for all subjects (left panel), healthy control subjects (middle panel), and T1D subjects (right panel), matched for HLA-DRB1*04:01 and tested using the proinsulin 79–90 tetramer. Differences in the distribution of tetramer positivity among the groups were calculated using a Mann-Whitney U test; an earlier study including some of these subjects has been reported (7). Solid horizontal lines represent medians and inter-quartile ranges. Dashed horizontal lines indicate threshold binding of the negative control tetramer. Susceptible INS gene I  =  INS VNTR I/I; protective INS gene III  =  INS VNTR I/III or III/III.</p

Impact of prolonged requirement for insulin on 90-day mortality in critically ill patients without previous diabetic treatments: a post hoc analysis of the CONTROLING randomized control trial

International audienceAbstract Background Stress hyperglycemia can persist during an intensive care unit (ICU) stay and result in prolonged requirement for insulin (PRI). The impact of PRI on ICU patient outcomes is not known. We evaluated the relationship between PRI and Day 90 mortality in ICU patients without previous diabetic treatments. Methods This is a post hoc analysis of the CONTROLING trial, involving 12 French ICUs. Patients in the personalized glucose control arm with an ICU length of stay ≥ 5 days and who had never previously received diabetic treatments (oral drugs or insulin) were included. Personalized blood glucose targets were estimated on their preadmission usual glycemia as estimated by their glycated A1c hemoglobin (HbA1C). PRI was defined by insulin requirement. The relationship between PRI on Day 5 and 90-day mortality was assessed by Cox survival models with inverse probability of treatment weighting (IPTW). Glycemic control was defined as at least one blood glucose value below the blood glucose target value on Day 5. Results A total of 476 patients were included, of whom 62.4% were male, with a median age of 66 (54–76) years. Median values for SAPS II and HbA1C were 50 (37.5–64) and 5.7 (5.4–6.1)%, respectively. PRI was observed in 364/476 (72.5%) patients on Day 5. 90-day mortality was 23.1% in the whole cohort, 25.3% in the PRI group and 16.1% in the non-PRI group ( p < 0.01). IPTW analysis showed that PRI on Day 5 was not associated with Day 90 mortality ( IPTW HR = 1.22; CI 95% 0.84–1.75; p = 0.29), whereas PRI without glycemic control was associated with an increased risk of death at Day 90 ( IPTW HR = 3.34; CI 95% 1.26–8.83; p < 0.01). Conclusion In ICU patients without previous diabetic treatments, only PRI without glycemic control on Day 5 was associated with an increased risk of death. Additional studies are required to determine the factors contributing to these results