Role of immune dysfunction in pathogenesis of type 1 diabetes mellitus in children

The association between interleukin family and diabetes mellitus and its complications: An overview of systematic reviews and meta-analyses

OBJECTIVE

To evaluate and summarize the association between interleukin (IL) concentrations and diabetes mellitus (DM) and its complications.

METHODS

Meta-analyses and eligible individual studies of observational studies investigating the associations between IL and DM and its complications were included. The random-effects model was used to estimate the summary effect, and the heterogeneity among studies was assessed using the Q-statistic and the I2 metric; The Egger's regression and the χ2 test were used to test for small study effects and excess significance bias.

RESULTS

This overview identified 34 meta-analyses that investigated the association between IL concentrations and DM and its complications. Meta-analyses of prospective studies indicated that elevated circulating IL-6 and IL-1β had predictive value for the incident of type 2 diabetes mellitus (T2DM), type 1 diabetes mellitus (T1DM) as well as gestational diabetes mellitus (GDM), and the overall Hazard Ratio (HR) of T2DM was 1.28 (95 % CI: 1.17, 1.40; P＜0.001) per 1 log pg/ml increment in IL-6 levels, however, there was no correlation between circulating IL-10 levels and DM. Meanwhile, the increased level of IL-6 was significantly associated several diabetic complications (Diabetic kidney disease[DKD], diabetic peripheral neuropathy[DPN], and cognitive impairment[CI]), and for the diabetic retinopathy (DR), the levels of IL-1β, IL-8 and IL-10 in the aqueous humor and vitreous humor, but not the blood were significantly correlated with it.

CONCLUSION

Multiple ILs, such as the IL-6 and IL-1β, are definitively linked to DM and its complications, and they may be new targets for the diagnosis and treatment, but stronger evidence needs to be confirmed by prospective studies with larger sample sizes and longer observation periods.

Correlation analysis between cytokines' profile, autoimmune antibodies and the duration of type 1 diabetes: A case control study in a specialized children's centre in Riyadh

OBJECTIVE

The aim of this study was to investigate the role of cytokines in children with T1D living in Saudi Arabia and their correlation with disease duration and autoimmune antibody markers.

METHODS

A case-control study was conducted in the endocrine clinic of King Abdullah Specialized Children's Hospital in Riyadh. A total of 274 T1D and healthy control children were enrolled in the study. 5 mL of venous blood samples were collected in the morning after 9 to 12 h of fasting in BD Vacutainer® EDTA tubes and centrifuged at 250g for 15 min at. Plasma was then stored at -20°C for detection of anti-islet, anti-GAD antibodies (Abs), and C-peptide using commercial ELISA kits from Thermo Fisher Scientific. The levels of cytokines were measured using commercial sandwich ELISA kits from Abcam.

RESULTS

Median differences in cytokine levels (IFN-γ, TNF-α, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-13, IL-18, IL-21, IL-35, and IL-37) were significantly higher in T1D patients compared with healthy controls (p-value < .001). Spearman's Rho correlation indicated that TNFα, IL-1β, IL-4, IL-10, IL-13, and IL-21 correlated significantly with T1D Abs (p-value = .01). HbA1C correlated negatively with IL-35 and IL-37, and positively with IL-18 (p-value = .01). Linear regression analysis showed a significant increase in anti-glutamic acid antibodies (GAD) in patients with >3 years of T1D duration.

CONCLUSION

Autoantibodies remained positive at high levels in our patients over a 3-year duration of the disease and correlated with specific cytokines. The clear correlations with disease duration and profile of specific cytokines could be targets for future therapeutic interventions.

Aqueous extract of Passiflora alata leaves modulates in vitro the indoleamine 2,3-dioxygenase (IDO) and CD86 expression in bone marrow-derived professional antigen-presenting cells polarizing NOD mice T cells to a Treg profile

Dendritic cells (DCs) and macrophages are professional antigen-presenting cells (pAPCs), numerous in the pancreas of nonobese diabetic (NOD) mice and playing an essential role in the autoimmune response of type 1 diabetes. The expression of the enzyme indoleamine 2,3-dioxygenase (IDO) is a critical factor for the tolerogenic activity of pAPCs, acting in the catabolism of tryptophan, providing metabolites that suppress the T cell effectors and induce T regulatory cells differentiation. Here we investigated the in vitro mechanisms of lyophilized aqueous extract from Passiflora alata leaves (LAEPAL) that modulates bone marrow-derived professional antigen-presenting cells (BM-pAPCs), affecting their ability to polarize T cells. A cell culture model was defined using mixed cultures of BM-pAPCs and T lymphocytes NOD mice with stressed MIN-6 cells as a source of pancreatic β cells antigens. We showed that the treatment with 300 µg/mL of LAEPAL induces a significant decrease in the CD4 and CD8 T effector lymphocytes proliferation from diabetic but not in non-diabetic mice, followed by a reduction of the IL-6 and IFN-γ cytokines release in the cell cultures supernatants. Moreover, we observed an increase of CD4⁺CD25⁺FoxP3⁺ Tregs in the cell cultures from diabetic mice. These results could be partially explained by the LAEPAL modulatory effects in BM-pAPCs, downregulating the CD86 co-stimulatory molecule expression, and increasing IDO-1 expression in F4/80+ BM-pAPCs. These results contribute to a better understanding of the polyphenols' immunomodulatory properties, meaning they could induce tolerogenic antigen-presenting cells, which could polarize T cells to a Treg profile and decrease the activity of CD4+ and CD8+ T effector cells.

The prevalence of small intestinal bacterial overgrowth in diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

We conducted this systematic review and meta-analysis to estimate the prevalence of SIBO in diabetic patients and to determine the association between SIBO and diabetes.

METHODS

A comprehensive literature search of the PubMed, Cochrane Library and EMBASE databases from inception to June 2021 was conducted for studies correlating SIBO with diabetes. Studies were screened, and relevant data were extracted and analysed. The pooled prevalence of SIBO among diabetic patients and the odds ratio of SIBO among diabetic patients compared with controls were calculated.

RESULTS

Fourteen studies including 1417 diabetic patients and 649 controls met the inclusion criteria. The pooled prevalence of SIBO in diabetes was 29% (95% CI 20-39%). The odds ratio of SIBO in diabetic patients was 2.91 (95% CI 0.82-10.32, p=0.1) compared with controls. Subgroup analyses showed that the prevalence of SIBO in diabetes was higher in studies using jejunal aspirate culture for diagnosis (39%, 95% CI 12-66%) than in those using the lactulose breath test (31%, 95% CI 18-43%) or glucose breath test (29%, 95% CI 14-43%). The prevalence of SIBO in diabetes was higher in studies conducted in Western countries (35%, 95% CI 21-49%) than in those conducted in Eastern countries (24%, 95% CI 14-34%), and the prevalence of SIBO in type 1 diabetes (25%, 95% CI 14%-36%) was not significantly different from that in type 2 diabetes (30%, 95% CI 13%-47%).

CONCLUSIONS

Twenty-nine percent of diabetic patients tested positive for SIBO, and the risk of SIBO in diabetic patients was 2.91 times higher than that in patients without diabetes. Diabetes could be a predisposing factor for the development of SIBO, especially among patients diagnosed by jejunal aspirate culture or those in Western populations.

Impaired Innate Immunity in Pediatric Patients Type 1 Diabetes-Focus on Toll-like Receptors Expression

Type 1 diabetes (DM1) is classified as an autoimmune disease. An uncontrolled response of B and T lymphocytes to the body's own tissues develops in the absence of immune tolerance. The main aim of the study was to evaluate the effect of the duration of type 1 diabetes in children on the expression of TLR receptors and the relationship with the parameters of glycemic control in patients. As a result, we showed significant differences in the level of TLR2, TLR4 and TLR9 expression in patients with DM1 in the early stage of the disease and treated chronically compared to the healthy group. Additionally, in this study, we found that the numbers of CD19+ B cells, CD3+ CD4+, CD3+ CD8+ T cells and NK cells are different for newly diagnosed DM1 individuals, patients receiving chronic treatment and for healthy controls, indicating an important role of these cells in killing pancreatic beta cells. Moreover, higher levels of IL-10 in patients with newly diagnosed DM1 have also been found, confirming the reports found in the literature.

Methanolic Extract of Sambucus ebulus Ameliorates Clinical Symptoms in Experimental Type 1 Diabetes through Anti-Inflammatory and Immunomodulatory Actions

Objective

Sambucus ebulus (SE), a famous traditional Iranian medicine, is grown in the north of Iran. As a traditional medicine with anti-inflammatory effects, SE has been utilized against inflammatory joint diseases, insect bites, infectious wounds, edema, and eczema. Type1 diabetes, is an autoimmune disease, characterized by the destruction of pancreatic beta cells by the immune system. For the first time, we investigated the effect of methanolic extract of SE on CD4+, CD8+ and regulatory T cells in experimental type 1 diabetes (T1D).

Materials and Methods

In this experimental study, fifty-six C57BL\6 mice in 8 groups (G1-G8), were enrolled. Diabetes was induced by a multiple low-dose streptozotocin (MLDS) protocol and mice were daily treated with SE extract at 200 and 400 mg/kg doses, for 35 days. Fasting blood glucose was weekly measured by a glucometer. Islets insulin content was analyzed by immunohistochemistry. Percentage of CD4+, CD8+ and regulatory T cells and cytokines production levels were evaluated by flow cytometer and ELISA, respectively.

Results

The clinical symptoms of diabetes were significantly alleviated in G2 group mice which received 400 mg/ kg SE extract. Immunohistochemistry analysis showed that the insulin content of islets increased in G2 group mice. Immunophenotyping analysis indicated that the percentage of CD4+ and CD8+ T cells in G2 group mice was significantly decreased. SE extract significantly increased the percentage of regulatory T cells. The extract in G2 and G4 groups mice significantly decreased IFN-γ and IL-17levels. The extract significantly increased IL-10 in G2 group mice.

Conclusion

The protective effect of SE extract in MLDS-induced diabetes could be partly due to a decrease of CD4+ and CD8+ T cells and an increase of Treg cells resulting in an inflammation reduction in the pancreatic islets.

Genetic association between interleukin-10 gene rs1518111 and rs3021094 polymorphisms and risk of type 1 diabetes and diabetic nephropathy in Egyptian children and adolescents

OBJECTIVE

Genetic and environmental factors have been implicated in etiopathogenesis and progression of type 1 diabetes mellitus (T1DM) and diabetic nephropathy (DN). Genetic association between interleukin-10 (IL-10) single nucleotide polymorphisms (SNPs) with T2DM and DN was recently established. We aimed to explore the potential genetic risk of IL-10 gene rs1518111 and rs3021094 SNPs in susceptibility to T1DM and DN.

RESEARCH DESIGN AND METHODS

Cross-sectional study included 140 T1DM children, of whom 74 had DN and 90 controls. IL-10 gene rs1518111 and rs3021094 SNP were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique of the extracted genomic DNA from participants. Odds ratios (ORs) and 95% confidence intervals (CIs) were applied to explore the association between IL-10 gene polymorphisms and the risk of T1DM and DN.

RESULTS

For rs1518111 SNP, AA genotype was associated with high risk of T1DM (OR = 4.53; CI = 2.11-9.74; p < 0.001), while A allele was associated with high risk of both T1DM (OR = 3.35; CI = 2.20-5.09; p < 0.001) and DN (OR = 2.36; CI = 1.27-4.38; p = 0.006). For rs3021094 SNP, AC genotype displayed lower risk to develop T1DM (OR = 0.35; CI = 0.13-0.94; p = 0.037), while A allele displayed higher risk to develop T1DM (OR = 1.69; CI = 1.11-2.56; p = 0.013). GA and AC haplotypes of rs1518111 and rs3021094 had lower ORs for having T1DM and DN, while GC had lower OR for having T1DM.

CONCLUSIONS

AA genotype and A allele of IL-10 rs1518111 SNP could be linked to increased risk for T1DM and DN among Egyptian children. None of rs3021094 genotypes or alleles displayed significant association with DN. GA and AC haplotypes could be protective against T1DM and DN susceptibility.

Enhanced STAT3 phosphorylation and PD-L1 expression in myeloid dendritic cells indicate impaired IL-27Ralpha signaling in type 1 diabetes

Interleukin 27 (IL-27), a member of the IL-12 family, is important for T cell differentiation; however, little is known about its effect on dendritic cells (DCs). IL-27 can activate multiple signaling cascades, including the JAK/STAT pathway, and depending on the setting it can both promote and antagonize inflammatory responses. An anti-inflammatory function of IL-27 has been reported in several autoimmune diseases; however, in type 1 diabetes (T1D), an autoimmune disease where autoreactive cytotoxic T cells attack insulin-producing beta cells, IL-27 has been shown to have a dual role and contradictory effects. Here, we show impaired IL-27 signaling in a large cohort of T1D patients (n = 51) compared to age- and gender-matched healthy donors. Increased expression of the IL-27 receptor subunit IL-27Ralpha mRNA in purified myeloid DCs (mDCs), detected by gene expression microarrays was mirrored by enhanced signal transduction in T1D mDCs in response to IL-27 stimulation. Higher STAT phosphorylation in T1D patients was also accompanied by elevated expression of the inhibitory molecules PD-L1, PD-L2 and PD-1, which may suggest not only immunomodulatory mechanisms of IL-27 in T1D but also a compensatory effort of T1D dendritic cells against the ongoing inflammation.

Interleukin-6 and Interleukin-15 as Possible Biomarkers of the Risk of Autoimmune Diabetes Development

Aim

The aim of our study was to assay circulating interleukin-15 (IL-15) and interleukin-6 (IL-6) levels and insulin resistance measured by two different methods in newly diagnosed autoimmune diabetes (AD) patients, their I° relatives, and healthy controls.

Material and Methods

The group studied consisted of 54 patients with AD (28 with Latent Autoimmune Diabetes in Adults (LADA) and 26 with type 1 diabetes (T1D)), 70 first-degree relatives, and 60 controls. IL-6, IL-15, and anti-islet antibodies concentrations were measured by ELISA method. Homeostatic model assessment-insulin resistance (HOMAIR) and estimated glucose disposal rate (eGDR) were calculated.

Results

The patients with AD had significantly higher IL-15, IL-6, and HOMAIR and lower eGDR than the controls (p < 0.001, respectively) and first-degree relatives (p < 0.001, respectively). Significantly higher IL-15 and IL-6 were shown in the relatives with positive Ab as compared to the relatives without antibodies (p < 0.001, respectively) and the controls (p < 0.001, respectively). IL-15 negatively correlated with eGDR (r = −0.436, p = 0.021) in LADA and positively with HOMAIR in LADA and T1D (r = 0.507, p < 0.001; r = 0.4209, p < 0.001).

Conclusions

Significantly higher IL-15 and IL-6 concentrations, HOMAIR, and markedly lower eGDR in newly diagnosed AD patients and first-degree relatives with positive anti-islet antibodies might suggest the role of these pro-inflammatory cytokines and insulin resistance in the pathogenesis of autoimmune diabetes. IL-15 and IL-6 might be used as biomarkers of the risk of autoimmune diabetes development, in particular IL-15 for LADA. Both methods of IR measurement appear equally useful for calculating insulin resistance in autoimmune diabetes.

Type 1 diabetes mellitus: Complex interplay of oxidative stress, cytokines, gastrointestinal motility and small intestinal bacterial overgrowth

BACKGROUND

Oxidative stress is risk factor in progression of diabetes. It can increase cytokine production via several different mechanisms. Inflammation can affect gut neural apparatus that may lead to dysmotility which may exaggerate occurrence of bacterial overgrowth in intestine. Thus, a study was planned to understand the complex interplay of oxidative stress, inflammatory cytokines, gut motility and small intestinal bacterial overgrowth in type 1 diabetes mellitus (T1DM) patients.

MATERIALS AND METHODS

Seventy-five T1DM patients and 75 healthy controls were enrolled. Small intestinal bacterial overgrowth (SIBO) and orocecal transit time (OCTT) were measured using noninvasive glucose and lactulose hydrogen breath tests, respectively. Plasma levels of interleukin-6 (IL-6), tissue necrosis factor-alfa (TNF-α) and interleukin-10 (IL-10) were measured in all subjects by ELISA. Oxidative stress and anti-oxidant parameters were measured by standard methods.

RESULTS

Out of 75 T1DM patients, 36 were males with Mean ± SD age 22.3 ± 5.2 years, IL-6, TNF-α and IL-10 were significantly higher (P < 0.05) in T1DM patients as compared to controls. Lipid peroxidation (LPO) was significantly increased (P < 0.001), while reduced glutathione (GSH) significantly decreased (P < 0.01), whereas superoxide dismutase (SOD) and catalase significantly higher (P < 0.05) in T1DM patients as compared to controls. Positive correlation was observed between glycated haemoglobin (HbA1c) levels with LPO and negative correlation with GSH. Further, there was positive correlation between LPO and inflammatory cytokines (IL-6 & IL-10). OCTT was delayed and SIBO significantly higher in patients as compared to controls. On comparison of T1DM based on duration of disease, effect of all parameters was more pronounced in disease duration ≥5 years.

CONCLUSION

This study indicates that there is association between hyperglycaemia, oxidative stress (LPO), anti-oxidants (GSH, SOD and catalase), inflammatory cytokines, gut motility (OCTT), and small intestinal overgrowth in type 1 diabetes mellitus patients. This association is intensified as duration of disease increases.

Increased Blood Levels of Growth Factors, Proinflammatory Cytokines, and Th17 Cytokines in Patients with Newly Diagnosed Type 1 Diabetes

The production of several cytokines could be dysregulated in type 1 diabetes (T1D). In particular, the activation of T helper (Th) type 1 (Th1) cells has been proposed to underlie the autoimmune pathogenesis of the disease, although roles for inflammatory processes and the Th17 pathway have also been shown. Nevertheless, despite evidence for the role of cytokines before and at the onset of T1D, the corresponding findings are inconsistent across studies. Moreover, conflicting data exist regarding the blood cytokine levels in T1D patients. The current study was performed to investigate genetic and autoantibody markers in association with the peripheral blood cytokine profiles by xMap multiplex technology in newly diagnosed young T1D patients and age-matched healthy controls. The onset of young-age T1D was characterized by the upregulation of growth factors, including granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-7, the proinflammatory cytokine IL-1β (but not IL-6 or tumor necrosis factor [TNF]-α), Th17 cytokines, and the regulatory cytokines IL-10 and IL-27. Ketoacidosis and autoantibodies (anti-IA-2 and -ZnT8), but not human leukocyte antigen (HLA) genotype, influenced the blood cytokine levels. These findings broaden the current understanding of the dysregulation of systemic levels of several key cytokines at the young-age onset of T1D and provide a further basis for the development of novel immunoregulatory treatments in this disease.

Regulatory T-cells in autoimmune diseases: challenges, controversies and--yet--unanswered questions

Regulatory T cells (Tregs) are central to the maintenance of self-tolerance and tissue homeostasis. Markers commonly used to define human Tregs in the research setting include high expression of CD25, FOXP3 positivity and low expression/negativity for CD127. Many other markers have been proposed, but none unequivocally identifies bona fide Tregs. Tregs are equipped with an array of mechanisms of suppression, including the modulation of antigen presenting cell maturation and function, the killing of target cells, the disruption of metabolic pathways and the production of anti-inflammatory cytokines. Treg impairment has been reported in a number of human autoimmune conditions and includes Treg numerical and functional defects and conversion into effector cells in response to inflammation. In addition to intrinsic Treg impairment, resistance of effector T cells to Treg control has been described. Discrepancies in the literature are common, reflecting differences in the choice of study participants and the technical challenges associated with investigating this cell population. Studies differ in terms of the methodology used to define and isolate putative regulatory cells and to assess their suppressive function. In this review we outline studies describing Treg frequency and suppressive function in systemic and organ specific autoimmune diseases, with a specific focus on the challenges faced when investigating Tregs in these conditions.