Impaired primary immune response in type-1 diabetes. Functional impairment at the level of APCs and T-cells

A better understanding of the role of the CTLA-CD80/86 axis in the treatment of autoimmune diseases

Autoimmune diseases are diseases in which the regulatory mechanisms of the immune response are disturbed. As a result, the body loses self-tolerance. Since one of the main regulatory mechanisms of the immune response is the CTLA4-CD80/86 axis, this hypothesis suggests that autoimmune diseases potentially share a similar molecular basis of pathogenesis. Hence, investigating the CTLA4-CD80/86 axis may be helpful in finding an appropriate treatment strategy. Therefore, this study aims to investigate the molecular basis of the CTLA4-CD80/86 axis in the regulation of the immune response, and then its role in developing some autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. As well, the main therapeutic strategies affecting the CTLA4-CD80/86 axis have been summarized to highlight the importance of this axis in management of autoimmune diseases.

SARS-CoV-2 vaccination in children and adolescents with and without type 1 diabetes mellitus

Adults with Diabetes Mellitus (DM) have increased risk of severe clinical presentation during COVID-19 infection, while children and adolescents with type 1 diabetes (T1D) have the same mild clinical course as their healthy peers, especially those with optimal glycemic control. The present review focuses on the necessity of COVID-19 vaccination among children and adolescents with T1D, and also in their non-diabetic peers. The efficacy and safety of COVID-19 vaccines are also discussed, as well as their various side-effects, ranging from common mild to very rare and serious ones. Furthermore, the results of COVID-19 vaccination of adolescents with and without T1D are reported, as well as the efficacy and concerns about childhood vaccination. It is concluded that patients with DM of all age groups should maintain optimal diabetic control in order to avoid glycemic deterioration during COVID-19 infection. Furthermore, despite the very rare and serious complications of COVID-19 vaccines, vaccination against COVID-19 is recommended for children and adolescents with T1D to prevent glycemic deterioration and rare but serious complications of COVID-19 infection.

Similar Time Course of Humoral Response to SARS-CoV-2 mRNA Vaccines in People With and Without Type 1 Diabetes

Objective: To assess whether the immunogenicity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines or breakthrough infection rates differ between patients with type 1 diabetes (T1D) and control subjects. Research Design and Methods: A prospective 12-month follow-up of 27 adults with T1D and 89 control subjects who received at least two doses of either the mRNA-1273 or BNT162b2 vaccine. Primary outcomes: total antibodies against the receptor-binding domain and neutralizing antibodies. A multivariate repeated measures model evaluated potential determinants of antibody response. Results: Neither antibody levels nor breakthrough infection rates after vaccination differed in T1D and non-T1D groups. Older age predicted lower antibody levels, whereas SARS-CoV-2 infection or booster vaccine resulted in higher antibody levels in both groups. mRNA-1273 was associated with higher antibody levels than BNT162b2 until 6 months after the first dose. Conclusions: Persons with and without T1D have similar humoral antibody responses to SARS-CoV-2 mRNA vaccines during 12-months of follow-up.

Positive association between stress hyperglycemia ratio and pulmonary infection in patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention

BACKGROUND

Previous studies have shown that the stress hyperglycemia ratio (SHR), a parameter of relative stress-induced hyperglycemia, is an excellent predictive factor for all-cause mortality and major adverse cardiovascular events (MACEs) among patients with ST-segment elevation myocardial infarction (STEMI). However, its association with pulmonary infection in patients with STEMI during hospitalization remains unclear.

METHODS

Patients with STEMI undergoing percutaneous coronary intervention (PCI) were consecutively enrolled from 2010 to 2020. The primary endpoint was the occurrence of pulmonary infection during hospitalization, and the secondary endpoint was in-hospital MACEs, composed of all-cause mortality, stroke, target vessel revascularization, or recurrent myocardial infarction.

RESULTS

A total of 2,841 patients were finally included, with 323 (11.4%) developing pulmonary infection and 165 (5.8%) developing in-hospital MACEs. The patients were divided into three groups according to SHR tertiles. A higher SHR was associated with a higher rate of pulmonary infection during hospitalization (8.1%, 9.9%, and 18.0%, P < 0.001) and in-hospital MACEs (3.7%, 5.1%, and 8.6%, P < 0.001). Multivariate logistic regression analysis demonstrated that SHR was significantly associated with the risk of pulmonary infection during hospitalization (odds ratio [OR] = 1.46, 95% confidence interval [CI] 1.06-2.02, P = 0.021) and in-hospital MACEs (OR = 1.67, 95% CI 1.17-2.39, P = 0.005) after adjusting for potential confounding factors. The cubic spline models demonstrated no significant non-linear relationship between SHR and pulmonary infection (P = 0.210) and MACEs (P = 0.743). In receiver operating characteristic curve, the best cutoff value of SHR for pulmonary infection was 1.073.

CONCLUSIONS

The SHR is independently associated with the risk of pulmonary infection during hospitalization and in-hospital MACEs for patients with STEMI undergoing PCI.

Immunogenicity and Safety of SARS-CoV-2 mRNA Vaccines in a Cohort of Patients With Type 1 Diabetes

Patients with type 1 diabetes (T1D) may develop severe outcomes during coronavirus disease 2019 (COVID-19), but their ability to generate an immune response against the SARS-CoV-2 mRNA vaccines remains to be established. We evaluated the safety, immunogenicity, and glycometabolic effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines in patients with T1D. A total of 375 patients (326 with T1D and 49 subjects without diabetes) who received two doses of the SARS-CoV-2 mRNA vaccines (mRNA-1273, BNT162b2) between March and April 2021 at ASST Fatebenefratelli Sacco were included in this monocentric observational study. Local and systemic adverse events were reported in both groups after SARS-CoV-2 mRNA vaccination, without statistical differences between them. While both patients with T1D and subjects without diabetes exhibited a parallel increase in anti-SARS-CoV-2 spike titers after vaccination, the majority of patients with T1D (70% and 78%, respectively) did not show any increase in the SARS-CoV-2-specific cytotoxic response compared with the robust increase observed in all subjects without diabetes. A reduced secretion of the T-cell-related cytokines interleukin-2 and tumor necrosis factor-α in vaccinated patients with T1D was also observed. No glycometabolic alterations were evident in patients with T1D using continuous glucose monitoring during follow-up. Administration of the SARS-CoV-2 mRNA vaccine is associated with an impaired cellular SARS-CoV-2-specific cytotoxic immune response in patients with T1D.

Higher Stress Hyperglycemia Ratio Is Associated With a Higher Risk of Stroke-Associated Pneumonia

Objective

Stroke-associated pneumonia (SAP) is a frequent complication in stroke patients. This present study aimed to investigate the association between stress hyperglycemia and SAP.

Methods

Patients were screened between February 2013 and August 2020 from the First Affiliated Hospital of Wenzhou Medical University. We divided the blood glucose of the patients at admission by the glycated hemoglobin to calculate the stress hyperglycemia ratio (SHR). Binary logistic regression analysis was used to identify the association between SAP and SHR, with the confounders being controlled. Further, subgroup analyses were separately performed for stroke patients with and without diabetes.

Results

A total of 2,039 patients were finally recruited, of which 533 (26.14%) were diagnosed with SAP. SHR were divided into four quartiles in the logistic regression analysis, the highest SHR quartile (SHR ≥ 1.15) indicated a higher risk of SAP (OR = 1.57; 95% CI = 1.13–2.19, p = 0.01) in total patients. In patients without diabetes, the third quantile (SHR = 0.96–1.14) and the highest quantile (SHR ≥ 1.15) were both related to a higher risk of SAP (both p < 0.05). However, we did not find such an association in diabetic patients.

Conclusion

SHR was significantly associated with the risk of SAP in patients without diabetes. Adequate attention should be paid to the patients with high SHR levels at admission, especially those without diabetes.

Decreased Ficolin-3-mediated Complement Lectin Pathway Activation and Alternative Pathway Amplification During Bacterial Infections in Patients With Type 2 Diabetes Mellitus

Bacterial infections are frequent and severe in patients with diabetes mellitus. Whether diabetes per se induces functional alterations in the complement system hampering activation during infection is unknown. We investigated key elements of the complement system during bacterial infections in patients with type 2 diabetes mellitus (T2DM) and compared them to non-diabetic (ND) individuals. Using a prospective design, we included 197 T2DM, and 196 ND subjects, all with clinical diagnosis of acute community-acquired bacterial infections. Functional activities of the ficolin-3-mediated lectin (F3-LP), mannose binding lectin-mediated lectin- (MBL-LP), classical (CP), and alternative pathways (AP), as well as concentrations of complement activation products C4d and sC5b-9 were determined. Functional in vitro activities of F3-LP and AP were significantly higher in T2DM than in ND subjects, (median 64% vs. 45%, p = 0.0354 and 75 vs. 28%, p = 0.0013, respectively), indicating a decreased in vivo activation and lack of consumption of F3-LP and AP in T2DM patients, whereas no difference in functional capacities of CP and MBL-LP were observed between T2DM and ND subjects. Diminished F3-LP and AP activation was most pronounced in diabetic patients with urinary tract infections with positive microbiological culture results for Escherichia coli bacteria. In the T2DM group 3-months mortality significantly associated with diminished F3-LP and AP, but not with CP activation. Concentrations of C4d and sC5b-9 were significantly lower in the T2DM than in ND patients. In conclusion, we found impaired F3-LP activation and lack of AP amplification during bacterial infections in patients with type 2 diabetes, compared to non-diabetic subjects, suggesting a diminished complement mediated protection to bacterial infections in T2DM.

Cytokine and Adhesion Molecule Expression Induced by Different Strains of Staphylococcus aureus in Type 1 Diabetic Rats: Role of Insulin

Introduction: Staphylococcus aureus may provoke peritonitis and death, especially in immunocompromized individuals such as diabetic patients. We evaluated the role of insulin in S. aureus-induced peritoneal infection in diabetic and non-diabetic rats. Materials/Methods: Alloxan-diabetic male Wistar rats and their respective controls received intraperitoneal injections of different strains of S. aureus or sterile phosphate-buffered saline. After 3 days of infection, the first set of diabetic and non-diabetic rats received 4 and 1 IU, respectively, of neutral protamine Hagedorn insulin and were analyzed 8 h later. The second set of diabetic and non-diabetic rats received 4 and 1 IU, respectively, of insulin 2 h before intraperitoneal infection and a half dose of insulin at 5 p.m. for the next 2 days and were analyzed 16 h later. The following measurements were performed: (a) number of cells in the peritoneal lavage fluid (PeLF), white blood cell count, and blood glucose; (b) serum insulin and corticosterone; (c) cytokine levels in the PeLF; (d) expression of adhesion molecules in the vascular endothelium; and (e) microbicidal activity. Results: Diabetic rats showed an increased number of polymorphonuclear leukocytes (PMNs) and increased concentrations of CINC-1, IL-4, and IFN-γ in the PeLF after infection with the ATCC 25923 or N315 αHL⁺ strain. The mesenteric expression of PECAM-1 was increased after infection with the N315 HLA⁺ strain. ICAM-1 expression was increased with ATCC infection. Treatment of diabetic rats with a single dose of insulin restored CINC-1 levels in the PeLF for both strains; however, PMN migration, IL-4, and IFN-γ were restored in rats infected with the ATCC strain, whereas the PeLF concentrations of CINC-2, IL-1β, and IL-4 were increased in N315-infected animals. Insulin restored PMN migration and CINC-2 levels in the PeLF in ATCC-infected rats. After multiple treatments with insulin, the levels of IL-1β, IL-6, and IFN-γ were increased in the PeLF of diabetic rats after infection with either strain, and CINC-2 levels were restored in N315-infected animals. Conclusion: These results suggest that insulin distinctively modulates cytokine production or release, PMN leukocyte migration, and adhesion molecule expression during the course of peritonitis induced by different strains of S. aureus.

Identification and functional characterization of CD8+ T regulatory cells in type 1 diabetes patients

Type 1 diabetes is an autoimmune disease where autoreactive T lymphocytes destroy pancreatic beta cells. We previously reported a defect in CD4⁺ Tregs cell proliferation and reduced CD4⁺ Tregs PD-1 expression in patients. Another ‘memory-like’ regulatory subset, CD8⁺ Tregs, evaluated as CD8⁺CD25⁺FOXP3⁺, has recently raised interest for their effective suppressive activity. Different CD8⁺ T cell populations, their proliferation capacity and expression of PD-1 molecule were evaluated by flow-cytometer analysis in newly diagnosed, long-term Type 1 diabetes patients compared to healthy normal donors. Under basal conditions, CD8⁺ Tregs and CD8⁺ Teffs were seemingly represented among study groups while there was evidence of diminished expression of PD-1 in Teff subsets of long-term patients. After 3 days of PMA/ionomycin stimulation, patients CD8⁺ Tregs showed decreased percentage in respect to control group. CD8⁺ Teffs were instead increased in long-term diabetics versus controls. PD-1⁺CD8⁺ Tregs were represented at a much lower percentage in long-term diabetic patients, in respect to controls. Importantly, patients CD8⁺ Tregs and CD8⁺ Teffs presented a significant proliferation defect in respect to the control group. In conclusion, our study indicates that a defect of CD8⁺ Tregs is observed in diabetics. This subset could thus represent a novel target of immunotherapy in patients.

Positive Bacteriological Analyses in Individuals With Diabetes Mellitus: Preliminary Results From a Forensic Study

Increased infection susceptibility in the diabetic population is a controversial issue in the clinical field. The greater frequency of infections in diabetic patients has been speculated as caused by the hyperglycemic environment that favors immune dysfunction. The aim of this study was to investigate the proportion of positive bacterial cultures in a series of diabetic individuals who underwent forensic investigations and assess the frequency of hyperglycemia at the time of death in these cases as well as the percentage of diabetics with cause of death due to bacterial infection. Forensic autopsy cases characterized by positive bacterial cultures and pre-existing diagnosis of diabetes mellitus were included in the study. Initial findings revealed that 12% (7/58 cases) of positive bacterial cultures concerned individuals with a pre-existing diagnosis of diabetes mellitus. Bacterial infection was considered to be the cause of death in 22% (7/31 cases) of diabetics with positive bacterial cultures. Hyperglycemia could be identified in 1 case only at the time of death. These preliminary results highlight the usefulness of systematically performing postmortem bacteriology in the forensic setting to more precisely characterize infectious risk factors in diabetics.

Review: The relationship of hemoglobin A1c to postoperative surgical risk with an emphasis on joint replacement surgery

Patients with diabetes mellitus are known to have a high risk of postoperative complications, including infections, impaired wound healing, cardiovascular events, venous thromboembolism, and mortality. Because hyperglycemia has been thought to mediate this risk, there is a clinical propensity for improving glycemic control, as assessed by hemoglobin A1c (HbA1c) level, prior to proceeding with elective surgery, particularly joint replacement surgery. However, it is not established whether chronic poor glycemic control, indicated by elevated HbA1c levels, predicts increased risk of postoperative complications. The benefit of improving glycemic control must be weighed against risks of delaying necessary elective surgery, such as joint replacement surgery, which risks may include negative impact on long-term glycemic control. Thus, we review the current evidence to determine the relationship between HbA1c and postoperative surgical risk, especially on joint replacement surgery.

Hyperglycaemia does not affect antigen-specific activation and cytolytic killing by CD8+ T cells in vivo

Metabolism is of central importance for T cell survival and differentiation. It is well known that T cells cannot function in the absence of glucose, but it is less clear how they respond to excessive levels of glucose. In the present study, we investigated how increasing levels of glucose affect T-cell-mediated immune responses. We examined the effects of increased levels of glucose on CD8⁺ T-cell behaviour in vitro by assessing activation and cytokine production, as well as oxygen consumption rate (OCR), extracellular acidification rate (ECAR) and intracellular signalling. In addition, we assessed in vivo proliferation, cytokine production and cytolytic activity of cells in chemically induced diabetic C57BL/6 mice. Elevated levels of glucose in in vitro cultures had modest effects on proliferation and cytokine production, while in vivo hyperglycaemia had no effect on CD8⁺ T-cell proliferation, interferon γ (IFNγ) production or cytolytic killing.

Association Between Diabetes Mellitus and Outcomes of Patients with Sepsis: A Meta-Analysis

Background

Diabetes mellitus (DM) is a critical medical problem that can make people more likely to develop infectious complications, even sepsis. However, the influence of DM on the outcomes of septic patients is still controversial. Thus, we conducted the present meta-analysis to investigate whether DM worsens outcomes of septic patients.

Material/Methods

We searched studies from PubMed, Embase, and Cochrane Library databases from 1966 to July 1, 2016. The primary outcome we chose was 28-day or 30-day mortality or in-hospital mortality.

Results

Our meta-analysis of 10 enrolled studies performed between 2000 and 2016 shows that the mortality rate of septic patients with DM was slightly lower than that of non-diabetic patients (risk ratio [RR]=0.97, 95% confidence interval [CI]: 0.96 to 0.98, P<0.00001). On the other hand, septic patients with DM had a shorter hospital stay (weighted mean difference (WMD)=−2.27, 95% CI: −4.11 to −0.44, P=0.01), a higher incidence rate of AKI (RR=1.56, 95% CI: 1.25 to 1.95, P<0.001), and a similar incidence of respiratory dysfunction (RR=0.86, 95% CI: 0.71 to 1.04, P=0.11) compared with those without DM.

Conclusions

The results from the meta-analysis suggest that DM does not impair the outcome of patients with sepsis, and the incidence of acute kidney injury increases dramatically in septic patients with DM. Due to the limitations of the analysis, more well-designed trials are still necessary.

Effects of diabetes mellitus on the clinical presentation and treatment response in tuberculosis

BACKGROUND AND OBJECTIVE

With the colliding global epidemics of diabetes mellitus (DM) and tuberculosis (TB), we studied the effects of DM on the presentation of TB and its response to treatment.

METHODS

Consecutive TB patients from 2006 to 2010 in a territory-wide treatment programme offering 9-month extended treatment for TB patients with DM were examined and followed up prospectively to assess their treatment response. Successful treatment completers were tracked through the TB registry and death registry for relapse, death or till 31 December 2014, whichever was the earliest.

RESULTS

DM was independently associated with more chest symptoms (adjusted OR (AOR): 1.13) and systemic symptoms (AOR: 1.30) but less with other site-specific symptoms (AOR: 0.58) at TB presentation. There was more frequent pulmonary involvement (AOR: 1.69), with more extensive lung lesion (AOR: 1.25), lung cavity (AOR: 2.00) and positive sputum smear (AOR: 1.83) and culture (AOR: 1.38), but no difference in the proportion of retreatment cases or isoniazid and/or rifampicin resistance. After treatment initiation, there was higher overall incidence (AOR: 1.38) of adverse effects (mainly gastrointestinal symptoms, renal impairment and peripheral neuropathy but less fever and skin hypersensitivity reactions), more smear non-conversion (AOR: 1.59) and culture non-conversion (AOR: 1.40) at 2 months, and lower combined cure/treatment completion rate at 12 months (AOR: 0.79), but no difference in the relapse rate after having successfully completed treatment.

CONCLUSION

DM adversely affected the clinical presentation and treatment response of TB, but there was no difference in the drug resistance and relapse rates.

Antibody Responses to Immunizations in Children with Type I Diabetes Mellitus: a Case-Control Study

Type I diabetes mellitus (DM) has been associated with abnormalities of T cells. Our objective was to assess whether antibody responses to T-cell-dependent and -independent antigens in children with DM are lower than those of children without DM. We performed a case-control study matching children with DM to children without DM by age and by assessing antibody levels to pneumococcal serotypes, Haemophilus influenzae, and tetanus and diphtheria toxoids and reassessing antibody levels in patients with antibody levels below protective thresholds after booster immunization. We recruited 36 children with DM and 36 age-matched controls. The mean age was 10 years. There was no difference between groups in antibody levels against the antigens tested. Pneumococcal antibody levels below the protective threshold were found in 35.9% of DM patients after conjugate pneumococcal vaccination with no difference between groups. Booster immunization with unconjugated pneumococcal vaccine resulted in a median level against pneumococcal serotypes of 2.3 μg/ml (range, 0.05 to 664.7 μg/ml) in children with DM and 6.1 μg/ml (0.12 to 203.36 μg/ml) in children without DM (P = 0.013). Over 85% of children had levels above the protective threshold after booster immunization with no difference between groups. There was no evidence for a reduced antibody response to T-cell-dependent antigens given during childhood immunizations in children with DM. There was a reduced antibody response to antigens of pneumococcal strains in children with DM given unconjugated pneumococcal polysaccharide vaccine compared to that of children without DM without being associated with a difference in percentage of antibody levels below the protective threshold between groups.

Pitfalls in diagnosing diabetic foot infections

Although the diagnosis of a diabetic foot infection is made based on clinical symptoms and signs, we also use blood laboratory, microbiological and radiological studies to make treatment decisions. All of these diagnostic studies have pitfalls that can lead to a delay in diagnosis. Such delays will likely lead to further tissue damage and to a higher chance of amputation. One of these pitfalls is that some clinicians rely on microbiological, rather than clinical data, to diagnose infection. Though subjective by nature, clinical signs predict outcome of foot infections accurately. Another pitfall is that microbiological data can be misleading. All wounds harbour microorganisms; therefore, a positive wound culture does not mean that a wound is infected. Furthermore, the outcome of cultures of wound swabs does not correlate well with culture results of tissue biopsies. Therapy guidance by wound swab will likely lead to overtreatment of non-pathogenic organisms. Genotyping might have a role in identifying previously unrecognized (combinations of) pathogens in diabetic foot infection, bacteria in sessile phenotype and non-culturable pathogens, e.g. in cases where antibiotics have already been administered. One more pitfall is that the diagnosis of osteomyelitis remains difficult. Although the result of percutaneous bone biopsy is the reference standard for osteomyelitis, some other diagnostic modalities can aid in the diagnosis. A combination of several of these diagnostic tests is probably a good strategy to achieve a higher diagnostic accuracy. Relying on a single test will likely lead to misidentification of patients with osteomyelitis with associated overtreatment and undertreatment.

Streptococcus pneumoniae oropharyngeal colonization in school-age children and adolescents with type 1 diabetes mellitus: Impact of the heptavalent pneumococcal conjugate vaccine

This study evaluated Streptococcus pneumoniae colonization in children and adolescents with type 1 diabetes mellitus (DM1) to investigate the theoretical risk of invasive pneumococcal disease (IPD) in these patients and the potential protective efficacy of pneumococcal conjugate vaccines (PCVs). An oropharyngeal swab was obtained from 299 patients aged 6-17 y with DM1 who were enrolled during routine clinical visits. DNA from swabs was analyzed for S. pneumoniae using real-time polymerase chain reaction. S. pneumoniae was identified in the swabs of 148 subjects (49.8%). Colonization was strictly age-related and declined significantly in the group aged ≥15 years (odds ratio [OR] 0.28; 95% confidence interval [CI], 0.14-0.57). Carriage was also significantly influenced by sex (lower in females: OR 0.56; 95% CI, 0.35-0.91), ethnicity (less common among non-Caucasians: OR 0.34; 95% CI, 0.13-0.89), parental smoking habit (more frequent among children with at least one smoker between parents: OR 1.76; 95% CI, 0.90-2.07), and the administration of antibiotic therapy in the previous 3 months (less frequent among patients who received antibiotics: OR 0.21; 95% CI, 0.07-0.62). Multivariate analyses of the entire study population showed no association between carriage and PCV7 vaccination status. Serotypes 19F, 9V, and 4 were the most frequently identified serotypes. In conclusion, school-age children and adolescents with DM1 are frequently colonized by S. pneumoniae, and protection against pneumococcal carriage following infant and toddler vaccination was not effective after several years. Together with the need to increase vaccine uptake in all the children aged <2 years, these results suggest that PCV booster doses are needed in DM1 patients to maintain the protection offered by these vaccinations.

CD4⁺ T-cell proliferation responses to wheat polypeptide stimulation in children at different stages of type 1 diabetes autoimmunity

AIMS

Our aim was to study whether immune responses to wheat-based proteins are related to the development of type 1 diabetes.

METHODS

We analysed proliferative T-cell responses after in vitro gliadin, gluten, whole wheat, and tetanus toxoid stimulation with a carboxyfluorescein succinimidyl ester (CFSE) based T-cell proliferation assay in children at various phases of type 1 diabetes autoimmunity and in healthy autoantibody-negative control children.

RESULTS

At an early stage of beta cell autoimmunity the strength and frequencies of positive proliferation responses to gliadin, gluten, and whole wheat did not differ between newly seroconverted children positive for one islet autoantibody and the controls. However, in prediabetic children with at least two islet autoantibodies and also in children with newly diagnosed type 1 diabetes positive T-cell responses to gliadin were significantly less frequent and the strength of gliadin responses was reduced when compared to the controls. No differences were seen in T-cell responses to wheat-based antigens when comparing children with long-lasting type 1 diabetes with healthy controls.

CONCLUSIONS/INTERPRETATION

Decreased in vitro T-cell responses to wheat-based antigens were observed in children with multiple islet autoantibodies and in those with newly diagnosed type 1 diabetes, probably reflecting a generally aberrant immune response during the development of type 1 diabetes.

Of Mice and Men: Protective and Pathogenic Immune Responses to West Nile virus Infection

West Nile virus, a mosquito-borne flavivirus, first emerged in the Western Hemisphere in 1999. Although the majority of infections are asymptomatic, WNV causes significant morbidity and mortality in a minority of individuals who develop neuroinvasive disease, in particular the elderly and immunocompromised. Research in animal models has demonstrated interactions between WNV and the innate and adaptive immune system, some of which protect the host and others which are deleterious. Studies of disease pathogenesis in humans are less numerous, largely due to the complexities of WNV epidemiology. Human studies that have been done support the notion that innate and adaptive immune responses are delicately balanced and may help or harm the host. Further human investigations are needed to characterize beneficial responses to WNV with the goal of such research leading to therapeutics and effective vaccines in order to control this emerging viral disease.

Does PGE₁ vasodilator prevent orthopaedic implant-related infection in diabetes? Preliminary results in a mouse model

BACKGROUND

Implant-related infections are characterized by bacterial colonization and biofilm formation on the prosthesis. Diabetes represents one of the risk factors that increase the chances of prosthetic infections because of related severe peripheral vascular disease. Vasodilatation can be a therapeutic option to overcome diabetic vascular damages and increase the local blood supply. In this study, the effect of a PGE₁ vasodilator on the incidence of surgical infections in diabetic mice was investigated.

METHODOLOGY

A S. aureus implant-related infection was induced in femurs of diabetic mice, then differently treated with a third generation cephalosporin alone or associated with a PGE₁ vasodilator. Variations in mouse body weight were evaluated as index of animal welfare. The femurs were harvested after 28 days and underwent both qualitative and quantitative analysis as micro-CT, histological and microbiological analyses.

RESULTS

The analysis performed in this study demonstrated the increased host response to implant-related infection in diabetic mice treated with the combination of a PGE₁ and antibiotic. In this group, restrained signs of infections were identified by micro-CT and histological analysis. On the other hand, the diabetic mice treated with the antibiotic alone showed a severe infection and inability to successfully respond to the standard antimicrobial treatment.

CONCLUSIONS

The present study revealed interesting preliminary results in the use of a drug combination of antibiotic and vasodilator to prevent implant-related Staphylococcus aureus infections in a diabetic mouse model.

Effect of hyperglycaemia on inflammatory and stress responses and clinical outcome of pneumonia in non-critical-care inpatients: results from an observational cohort study

AIMS/HYPOTHESIS

Despite the condition's high prevalence, the influence of hyperglycaemia on clinical outcomes in non-critical-care inpatients with infections remains ill defined. In this study, we analysed associations of glucose levels at admission and during initial inpatient treatment with the inflammatory response and clinical outcome in community-acquired pneumonia (CAP) patients.

METHODS

This secondary observational analysis included 880 confirmed CAP patients. We used severity-adjusted multivariate regression models to investigate associations of initial and 96 h mean glucose levels with serially measured biomarker levels over 7 days (C-reactive protein [CRP], procalcitonin, white blood cell count [WBC], pro-adrenomedullin [ProADM]) and adverse clinical course (death and intensive-care unit admission).

RESULTS

In the 724 non-diabetic patients (82.3% of the study population), moderate or severe hyperglycaemia (glucose 6-11 mmol/l and >11 mmol/l, respectively) was associated with increased risk for adverse clinical course (adjusted OR [95% CI] 1.4 [0.8, 2.4] and 3.0 [1.1, 8.0], respectively) and with higher CRP, WBC and ProADM levels over 7 days (p < 0.05, ANOVA, all days). In diabetic patients (n = 156), no similar associations were found for initial hyperglycaemia, although mean 96 h glucose levels  ≥ 9 mmol/l were associated with adverse clinical course (adjusted OR 5.4 [1.1, 25.8]; p = 0.03). No effect modification by insulin treatment was detected (interaction terms p > 0.2 for all analyses).

CONCLUSIONS/INTERPRETATION

Initial hyperglycaemia in non-diabetic CAP patients, and prolonged hyperglycaemia in diabetic or non-diabetic CAP patients, are associated with a more pronounced inflammatory response and CAP-related adverse clinical outcome. Optimal glucose targets for insulin treatment of hyperglycaemia in non-critical-care settings should be defined.

Diagnosis and management of infection in the diabetic foot

Foot infections are common in persons with diabetes mellitus. Most diabetic foot infections occur in a foot ulcer, which serves as a point of entry for pathogens. Unchecked, infection can spread contiguously to involve underlying tissues, including bone. A diabetic foot infection is often the pivotal event leading to lower extremity amputation, which account for about 60% of all amputations in developed countries. Given the crucial role infections play in the cascade toward amputation, all clinicians who see diabetic patients should have at least a basic understanding of how to diagnose and treat this problem.

Diabetic mouse model of orthopaedic implant-related Staphylococcus aureus infection

Background

Periprosthetic bacterial infections represent one of the most challenging orthopaedic complications that often require implant removal and surgical debridement and carry high social and economical costs. Diabetes is one of the most relevant risk factors of implant-related infection and its clinical occurrence is growing worldwide. The aim of the present study was to test a model of implant-related infection in the diabetic mouse, with a view to allow further investigation on the relative efficacy of prevention and treatment options in diabetic and non-diabetic individuals.

Methodology

A cohort of diabetic NOD/ShiLtJ mice was compared with non-diabetic CD1 mice as an in vivo model of S. aureus orthopaedic infection of bone and soft tissues after femur intramedullary pin implantation. We tested control and infected groups with 1×10³ colony-forming units of S. aureus ATCC 25923 strain injected in the implant site. At 4 weeks post-inoculation, host response to infection, microbial biofilm formation, and bone damage were assessed by traditional diagnostic parameters (bacterial culture, C-reactive protein and white blood cell count), histological analysis and imaging techniques (micro computed tomography and scanning electron microscopy).

Results

Unlike the controls and the CD1 mice, all the diabetic mice challenged with a single inoculum of S. aureus displayed severe osteomyelitic changes around the implant.

Conclusions

Our findings demonstrate for the first time that the diabetic mouse can be successfully used in a model of orthopaedic implant-related infection. Furthermore, the same bacteria inoculum induced periprosthetic infection in all the diabetic mice but not in the controls. This animal model of implant-related infection in diabetes may be a useful tool to test in vivo treatments in diabetic and non-diabetic individuals.

Differential effect of hyperglycaemia on the immune response in an experimental model of diabetes in BALB/cByJ and C57Bl/6J mice: participation of oxidative stress

Diabetes is associated with an increased risk of death from infectious disease. Hyperglycaemia has been identified as the main factor contributing to the development of diseases associated with diabetes mellitus. However, experimental evidence indicates individual susceptibility to develop complications of diabetes. In this context, the aim of this work was to study the immune response in a streptozotocin-induced type 1 diabetes in two mouse strains: BALB/cByJ and C57Bl/6J. The participation of hyperglycaemia and oxidative stress was also analysed. Diabetic BALB/cByJ mice showed a decrease in both the in-vivo and in-vitro immune responses, whereas diabetic C57Bl/6J mice had higher blood glucose but exhibited no impairment of the immune response. The influence of hyperglycaemia over the immune response was evaluated by preincubation of lymphocytes from normal mice in a high glucose-containing medium. T and B cells from BALB/cByJ mice showed a decrease in cell viability and mitogen-stimulated proliferation and an increase in apoptosis induction. An increase in oxidative stress was implicated in this deleterious effect. These parameters were not affected in the T and B lymphocytes from C57Bl/6J mice. In conclusion, BALB/cByJ mice were sensitive to the deleterious effect of hyperglycaemia, while C57BL/6J were resistant. Although an extrapolation of these results to clinical conditions must be handled with caution, these results highlight the need to contemplate the genetic background to establish models to study the deleterious effect of diabetes in order to understand phenotypical variations that are of clinical importance in the treatment of patients.

Upregulation of proinflammatory cytokine production in response to bacterial pathogen-associated molecular patterns in dogs with diabetes mellitus undergoing insulin therapy

BACKGROUND

Metabolic alterations associated with diabetes mellitus alter innate immunity. Dogs often develop infectious or inflammatory complications related to diabetes mellitus, yet little is known about the effects of diabetes mellitus on the immune system in this species.

METHODS

Prospective evaluation in dogs with poorly regulated spontaneous type 1 diabetes mellitus (T1DM). In vitro leukocyte cytokine response to lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PG) was compared between dogs with T1DM and healthy dogs. Additionally, the effect of acute in vitro glucose exposure on leukocyte tumor necrosis factor (TNF) production from healthy dogs was measured.

RESULTS

Leukocytes from dogs with T1DM had significantly greater TNF production after LTA and PG stimulation compared with leukocytes from healthy dogs. Leukocyte interleukin (IL)-6 production was greater after stimulation with LPS, LTA, PG, and phosphate-buffered saline in the T1DM group. No such difference was noted when evaluating IL-10 production between groups regardless of stimulant. Dogs with T1DM had significantly greater IL-6 to IL-10 production ratios than healthy dogs. Acute exposure to dextrose did not augment cytokine production from healthy canine leukocytes.

CONCLUSIONS

Dogs with T1DM have altered innate immunity characterized by upregulation of proinflammatory cytokine production without a concurrent change in anti-inflammatory cytokine production. This may be one explanation for the common infectious and inflammatory complications associated with T1DM in dogs.

Diabetes is not associated with increased mortality in emergency department patients with sepsis

STUDY OBJECTIVE

Despite its high prevalence, the influence of diabetes on outcomes of emergency department (ED) patients with sepsis remains undefined. Our aim is to investigate the association of diabetes and initial glucose level with mortality in patients with suspected infection from the ED.

METHODS

Three independent, observational, prospective cohorts from 2 large US tertiary care centers were studied. We included patients admitted to the hospital from the ED with suspected infection. We investigated the association of diabetes and inhospital mortality within each cohort separately and then overall with logistic regression and generalized estimating equations adjusted for age, sex, disease severity, and sepsis syndrome. We also tested for an interaction between diabetes and hyperglycemia/hypoglycemia.

RESULTS

A total of 7,754 patients were included. The mortality rate was 4.3% (95% confidence interval [CI] 3.9% to 4.8%) and similar in diabetic and nondiabetic patients (4.1% versus 4.4%; absolute risk difference 0.4%; 95% CI -0.7% to 1.4%). There was no significant association between diabetes and mortality in adjusted analysis (odds ratio [OR] overall 0.85; 95% CI 0.71 to 1.01). Diabetes significantly modified the effect of hyperglycemia and hypoglycemia with mortality; initial glucose levels greater than 200 mg/dL were associated with higher mortality in nondiabetic patients (OR 2.1; 95% CI 1.4 to 3.0) but not in diabetic patients (OR 1.0; 95% CI 0.2 to 4.7), whereas glucose levels less than 100 mg/dL were associated with higher mortality mainly in the diabetic population (OR 2.3; 95% CI 1.6 to 3.3) and to a lesser extent in nondiabetic patients (OR 1.1; 95% CI 1.03 to 1.14).

CONCLUSION

We found no evidence for a harmful association of diabetes and mortality in patients across different sepsis severities. High initial glucose levels were associated with adverse outcomes in the nondiabetic population only. Further investigation is warranted to determine the mechanism for these effects.

The impact of diabetes on the pathogenesis of sepsis

Diabetes is associated with an increased susceptibility to infection and sepsis. Conflicting data exist on whether the mortality of patients with sepsis is influenced by the presence of diabetes, fuelling the ongoing debate on the benefit of tight glucose regulation in patients with sepsis. The main reason for which diabetes predisposes to infection appears to be abnormalities of the host response, particularly in neutrophil chemotaxis, adhesion and intracellular killing, defects that have been attributed to the effect of hyperglycaemia. There is also evidence for defects in humoral immunity, and this may play a larger role than previously recognised. We review the literature on the immune response in diabetes and its potential contribution to the pathogenesis of sepsis. In addition, the effect of diabetes treatment on the immune response is discussed, with specific reference to insulin, metformin, sulphonylureas and thiazolidinediones.

DNA-protective effects of quercetin or naringenin in alloxan-induced diabetic mice

Diabetes mellitus is associated with a high production of reactive oxygen species, which may cause oxidative DNA damage. High levels of genomic damage have been associated with liver and renal failure as well as immune-system decline. Flavonoids are effective antioxidants and may protect against several chronic diseases including diabetes. This study used the comet assay to assess the levels of DNA damage in the blood, liver and kidney cells in untreated and quercetin (QU) or naringenin treated diabetic mice. In addition, the study was designed to establish whether QU or naringenin might have a biological effect in protecting diabetic mice against oxidative stress by using survival studies to observe total body injury at the level of the organism. QU or naringenin were injected to mice intraperitoneally (i.p.) at a dose of 50mg/kg for 7days starting 2days after a single dose (75mg/kg, i.v.) alloxan injection. These findings suggest that QU or naringenin treatment resulted in a significant increase in the body weight, the haematological and immunological parameters of blood, as well as leading to 100% survival of diabetic mice. The tested flavonoids have protective effects against alloxan-induced DNA-damage in peripheral lymphocytes but not in the liver and kidney cells of diabetic mice. It might be hypothesised that diabetic mice with a high intake of flavonoid-rich foods, and specifically foods rich in quercetin or naringenin, might be relatively protected against long-term complications of diabetes due to decreased oxidative stress. Various co-operative and synergistic action mechanisms of the tested flavonoids may lead to the protection of the whole organism against diabetes.

Autoantigen-specific regulatory T cells induced in patients with type 1 diabetes mellitus by insulin B-chain immunotherapy

There is a growing body of evidence to suggest that the autoimmunity observed in type 1 diabetes mellitus (T1DM) is the result of an imbalance between autoaggressive and regulatory cell subsets. Therapeutics that supplement or enhance the existing regulatory subset are therefore a much sought after goal in this indication. Here, we report the results of a double blind, placebo controlled, phase I clinical trial of a novel antigen-specific therapeutic in 12 subjects with recently diagnosed T1DM. Our primary objective was to test its safety. The study drug, human insulin B-chain in incomplete Freund's adjuvant (IFA) was administered as a single intramuscular injection, with subjects followed for 2 years. All subjects completed therapy and all follow-up visits. The therapy was generally safe and well-tolerated. Mixed meal stimulated C-peptide responses, measured every 6 months, showed no statistical differences between arms. All patients vaccinated with the autoantigen, but none who received placebo, developed robust insulin-specific humoral and T cell responses. Up to two years following the single injection, in peripheral blood from subjects in the experimental arm, but not the control arm, insulin B-chain-specific CD4+ T cells could be isolated and cloned that showed phenotypic and functional characteristics of regulatory T cells. The induction of a lasting, robust immune response generating autoantigen-specific regulatory T cells provides strong justification for further testing of this therapy in type 1 diabetes. (clinicaltrials.gov identifier NCT00057499).

Activation of B cells by antigens on follicular dendritic cells

A need for antigen-processing and presentation to B cells is not widely appreciated. However, cross-linking of multiple B cell receptors (BCRs) by T-independent antigens delivers a potent signal that induces antibody responses. Such BCR cross-linking also occurs in germinal centers where follicular dendritic cells (FDCs) present multimerized antigens as periodically arranged antigen-antibody complexes (ICs). Unlike T cells that recognize antigens as peptide-MHC complexes, optimal B cell-responses are induced by multimerized FDC-ICs that simultaneously engage multiple BCRs. FDC-FcgammaRIIB mediates IC-periodicity and FDC-BAFF, FDC-IL-6 and FDC-C4bBP are co-stimulators. Remarkably, specific antibody responses can be induced by FDC-ICs in the absence of T cells, opening up the exciting possibility that people with T cell insufficiencies may be immunized with T-dependent vaccines via FDC-ICs.

A DNA vaccine-encoded nucleoprotein of influenza virus fails to induce cellular immune responses in a diabetic mouse model

Influenza virus infections cause yearly epidemics and are a major cause of lower respiratory tract illnesses in humans worldwide. Influenza virus has long been recognized to be associated with higher morbidity and mortality in diabetic patients. Vaccination is an effective tool to prevent influenza virus infection in this group of patients. Vaccines employing recombinant-DNA technologies are an alternative to inactivated virus and live attenuated virus vaccines. Internal highly conserved viral nucleoprotein (NP) can be delivered as a DNA vaccine to provide heterosubtypic immunity, offering resistance against various influenza virus strains. In this study, we investigated the efficacy of an NP DNA vaccine for induction of cell-mediated immune responses and protection against influenza virus infection in a mouse model of diabetes. Healthy and diabetic BALB/c mice were immunized on days 0, 14, and 28 by injection of NP DNA vaccine. Two weeks after the last immunization, the cellular immune response was evaluated by gamma interferon (IFN-gamma), lymphocyte proliferation, and cytotoxicity assays. The mice were challenged with influenza virus, and the viral titers in the lungs were measured on day 4. Diabetic mice showed significantly smaller amounts of IFN-gamma production, lymphocyte proliferation, and cytotoxicity responses than nondiabetic mice. Furthermore, higher titers of the influenza virus were detected after challenge in the lungs of the diabetic mice. The present data suggest that the NP DNA vaccine with the protocol of immunization described here is not able to induce efficient cellular immune responses against influenza virus infection in diabetic mice.

Evaluation of human antibody responses to keyhole limpet hemocyanin on a carbohydrate microarray

PURPOSE

Keyhole limpet hemocyanin (KLH) is used as a vaccine adjuvant, as a carrier protein for small haptens, and as a treatment for bladder cancer. Immunization with KLH produces antibodies to tumor-associated carbohydrate antigens (TACAs) in animals, and these antibodies have been postulated as the basis of efficacy for bladder cancer treatment. The purpose of this study was to evaluate antibody responses to KLH in humans.

EXPERIMENTAL DESIGN

A carbohydrate microarray was used to profile antibody responses in 14 individuals immunized with KLH plus alum adjuvant.

RESULTS

Eight out of fourteen individuals produced antibodies to at least one TACA. Increases to Lewis X, Lewis Y, GA1di, GM3, and sialyl Lewis A were observed in certain individuals, but, in general, antibody profiles were highly variable. Pre-immunization antibody levels to a subset of array antigens had a statistically significant correlation with the magnitude of the antibody response to KLH.

CONCLUSIONS AND CLINICAL RELEVANCE

Antibodies to TACAs can be produced in humans, but antibody profiles differ considerably from person to person, which may contribute to variable clinical responses with KLH. Pre-treatment antibody levels to certain antigens may be useful for predicting which patients will respond favorably to KLH.

T-independent antibody responses to T-dependent antigens: a novel follicular dendritic cell-dependent activity

Follicular dendritic cells (FDCs) periodically arrange membrane-bound immune complexes (ICs) of T-dependent Ags 200-500A apart, and in addition to Ag, they provide B cells with costimulatory signals. This prompted the hypothesis that Ag in FDC-ICs can simultaneously cross-link multiple BCRs and induce T cell-independent (TI) B cell activation. TI responses are characterized by rapid IgM production. OVA-IC-bearing FDCs induced OVA-specific IgM in anti-Thy-1-pretreated nude mice and by purified murine and human B cells in vitro within just 48 h. Moreover, nude mice immunized with OVA-ICs exhibited well-developed GL-7(+) germinal centers with IC-retaining FDC-reticula and Blimp-1(+) plasmablasts within 48 h. In contrast, FDCs with unbound-OVA, which would have free access to BCRs, induced no germinal centers, plasmablasts, or IgM. Engagement of BCRs with rat-anti-mouse IgD (clone 11-26) does not activate B cells even when cross-linked. However, B cells were activated when anti-IgD-ICs, formed with Fc-specific rabbit anti-rat IgG, were loaded on FDCs. B cell activation was indicated by high phosphotyrosine levels in caps and patches, expression of GL-7 and Blimp-1, and B cell proliferation within 48 h after stimulation with IC-bearing FDCs. Moreover, anti-IgD-IC-loaded FDCs induced strong polyclonal IgM responses within 48 h. Blockade of FDC-FcgammaRIIB inhibited the ability of FDC-ICs to induce T-independent IgM responses. Similarly, neutralizing FDC-C4BP or -BAFF, to minimize these FDC-costimulatory signals, also inhibited this FDC-dependent IgM response. This is the first report of FDC-dependent but TI responses to T cell-dependent Ags.

Type 1 diabetes patients have significantly lower frequency of plasmacytoid dendritic cells in the peripheral blood

Dendritic cells uniquely orchestrate the delicate balance between T cell immunity and regulation and an imbalance favoring immunogenic rather than tolerogenic DC is believed to contribute to the development of autoimmune diseases such as type 1 diabetes (T1D). In this study, we determined the frequencies of three blood DC subsets (pDC, mDC1 and mDC2) in 72 T1D patients and 75 normal controls using the Miltenyi blood DC enumeration kit. The frequency of blood pDC was found to be negatively correlated with subject age in both normal controls and T1D patients (p=0.0007), while the frequency of mDC1 and mDC2 do not change significantly with subject age. More importantly, the mean frequency of pDC in blood was, after adjusting for age, significantly lower in T1D (mean=0.127%) than controls (mean=0.188%) (p<6.0 x 10(-5)), whereas no difference was observed for mDC1 and mDC2 between T1D and controls. Furthermore, T1D patients have a lower proportion of pDC and higher proportion of mDC1 among the total blood DC population than normal controls. These results indicate that the frequency of blood pDC and the pDC/mDC1 ratio are negatively associated with T1D.

Tuberculosis susceptibility of diabetic mice

Increased susceptibility to infections, including tuberculosis (TB), is a major cause of morbidity and mortality in patients with diabetes. Despite the clinical importance of this problem, little is known about how diabetes impairs protective immunity. We modeled this phenomenon by infecting acute (< or = 1 mo) or chronic (> or = 3 mo) diabetic mice with a low aerosol dose of Mycobacterium tuberculosis (Mtb) Erdman. Diabetes was induced by streptozotocin (STZ) treatment of C57BL/6 mice, while another mouse strain and diabetes model were used to confirm key observations. Lungs from acute diabetic and euglycemic mice had similar bacterial burdens, cytokine expression profiles, and histopathology. In contrast, chronic diabetic mice had > 1 log higher bacterial burden and more inflammation in the lung compared with euglycemic mice. The expression of adaptive immunity was delayed in chronic diabetic mice, shown by reduced early production of IFN-gamma in the lung and by the presence of fewer Mtb antigen (ESAT-6)-responsive T cells compared with euglycemic mice within the first month of infection. However, after 2 months of TB disease proinflammatory cytokines levels were higher in chronic diabetic than euglycemic mice. Here we show that Mtb infection of STZ-treated mice provides a useful model to study the effects of hyperglycemia on immunity. Our data indicate that the initiation of adaptive immunity is impaired by chronic hyperglycemia, resulting in a higher steady-state burden of Mtb in the lung.

Reduced CD4+ T-cell-specific gene expression in human type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) in humans is characterized by the T-cell-dependent destruction of the insulin producing pancreatic beta cells; however, the precise pathogenesis of the disease, especially the initiation of pathologic immune response, is still largely unknown. We hypothesized that the function of human CD4+ T cells is altered in T1DM and analyzed unstimulated human peripheral blood CD4+ T-cell gene expression. We used a novel three-way comparison of DNA microarray data of CD4+ T cells isolated from patients with new onset T1DM, patients with long-term Type 2 diabetes (T2DM), and from healthy control subjects in order to eliminate any possible influence of glucose homeostasis on our findings. We analyzed the T1DM specific gene-expression changes and their functional relevance to T1DM autoimmunity. Our genetic and functional data show that T1DM CD4+ T cells are down-regulated specifically affecting key immune functions and cell cycle. Histone deacetylase gene expression, a key regulator of epigenetic modification is also reduced. The CD4+ T cells showed impaired function, including an abnormal immune response, which may be a key element that leads to the breakdown of self-tolerance.

Common infections in diabetes: pathogenesis, management and relationship to glycaemic control

Specific defects in innate and adaptive immune function have been identified in diabetic patients in a range of in vitro studies. However, the relevance of these findings to the integrated response to infection in vivo remains unclear, especially in patients with good glycaemic control. Vaccine efficacy seems adequate in most diabetic patients, but those with type 1 diabetes and high glycosylated haemoglobin levels are most likely to exhibit hypo-responsiveness. While particular infections are closely associated with diabetes, this is usually in the context of extreme metabolic disturbances such as ketoacidosis. The link between glycaemic control and the risk of common community-acquired infections is less well established but could be clarified if infection data from large community-based observational or intervention studies were available. The relationship between hospital-acquired infections and diabetes is well recognized, particularly among post-operative cardiac and critically ill surgical patients in whom intensive insulin therapy improves clinical outcome independent of glycaemia. Nevertheless, further research is needed to improve our understanding of the role of diabetes and glycaemic control in the pathogenesis and management of community- and hospital-acquired infections.

Decreased production of inflammatory cytokines by circulating monocytes and dendritic cells in type 2 diabetic men with atherosclerotic complications

Antigen-presenting cells (APCs) are involved in the development of atherosclerosis, whose complications represent the main cause of death in diabetic patients. Nevertheless, their role in atherogenesis is poorly understood. We compared the number of circulating monocyte and dendritic cell (DC) subsets as well as their capacity to produce inflammatory cytokines IL-1beta, IL-6, and tumor necrosis factor-alpha (TNF-alpha) in type 2 diabetic men with (n=11) and without (n=44) chronic atherosclerotic complications. Identification and enumeration of peripheral blood (PB) lymphoid subsets, monocytes, myeloid (CD33strong+), CD16+, and plasmacytoid (CD33-/dim+) DCs as well as of their spontaneous and stimulated production of IL-1beta, IL-6, and TNF-alpha were performed at the single-cell level by flow cytometry. Our results show that type 2 diabetic men with atherosclerotic complications display a significantly reduced spontaneous secretion of IL-6 by monocytes and CD16+ DCs and of TNF-alpha by CD16+ DCs as compared to patients without atherosclerotic complications. Spontaneous secretion of IL-1beta by monocytes and CD16 DCs and of IL-6 by CD33+ and plasmacytoid DCs was detected in patients without atherosclerotic complications but not in the other patients with complications. Taken together, these results indicate that type 2 diabetic men with atherosclerotic complications display both quantitatively and functionally impaired immunological responses by circulating APCs. The decreased patterns of inflammatory cytokine production by these cells may influence the inflammatory response mediated by APCs as well as the antigen-specific responses mediated by other cells such as T cells.

Undiagnosed dysglycaemia and inflammation in cardiovascular disease

BACKGROUND

Cardiovascular (CV) disease is associated with increased levels of glucose, but the prevalence of dysglycaemia in CV diseases is not fully known. The study examined the prevalence of unknown dysglycaemia and its association with inflammation in Caucasian patients with ischaemic vascular complications, i.e. coronary artery disease (CAD), cerebrovascular disease (CVD) and peripheral artery disease (PAD).

MATERIALS AND METHODS

This case-controlled study involved 149 patients (mean age 68 years) hospitalized for CAD, PAD or CVD and 59 control-subjects (CTR) free from CV-disease. The prevalence of dysglycaemia according to WHO/ADA criteria (impaired fasting glycaemia, impaired glucose tolerance or diabetes mellitus) was assessed by a 75-g oral glucose tolerance test. Inflammatory parameters were analyzed in fasting samples.

RESULTS

Dysglycaemia was found in 49%, 55% and 57% of patients with CAD, CVD and PAD, respectively; all were significantly higher than among the controls (29%). The odds ratio (95% CI) for being dysglycaemic were 1.7 (1.04-2.77), 1.9 (1.19-3.06) and 2.0 (1.25-3.19) for CAD, CVD and PAD, respectively. Inflammatory markers (the total leucocyte count, soluble tumour necrosis factor-receptor type I, C-reactive protein) were elevated in patient groups and tended to increase with increasing blood glucose levels in all groups. The levels of the anti-inflammatory cytokine transforming growth factor-beta1 and insulin-like growth factor binding protein 3 were lowered in patients with CAD and, in patients with PAD, the former was inversely related to the levels of the blood glucose.

CONCLUSIONS

Undiagnosed dysglycaemia was common in patients with ischaemic CV manifestations regardless of vascular bed involved. Inflammation was associated in a dosage-related manner to glucose levels.

Reduced IFN-alpha secretion by blood dendritic cells in human diabetes

Characterization of dendritic cells (DC) in human diabetes has been restricted to monocyte-derived DC in type 1 diabetes, whose physiological relevance to endogenous DC is uncertain. Here, we provide the first report characterizing the phenotype and function of endogenous DC subsets in type 1 and type 2 diabetes. We show that DC subsets in each diabetic group exhibit normal properties concerning frequency and activation state, as determined using 4-color flow cytometry of whole blood cells. DC maturation is also intact as confirmed by their efficacious ability to stimulate T cell proliferation in an allogeneic MLR assay. Yet we found that DC are poor producers of IFN-alpha (P < 0.05) in human diabetes. IFN-alpha is a potent antiviral agent and therefore its reduced levels may interfere with T cell-mediated immune responses leading to increased susceptibility and persistence of infections in persons with diabetes.

Lipopolysaccharide regulated protein expression is only partly impaired in monocytes from patients with type I diabetes

BACKGROUND

Monocytes play an important role in innate immunity and atherosclerosis. A disturbed secretion of cytokines in lipopolysaccharide (LPS) activated monocytes from type 1 diabetes (T1D) patients has been described and may contribute to the impaired inflammatory response in these individuals. In the present study the influence of LPS on five different proteins with a function in immunity and atherosclerosis was analyzed in monocytes from controls and T1D patients.

METHODS

Monocytes were isolated from controls and T1D patients and the LPS-stimulated increase of IL-6, CXCL8, monocyte chemotactic protein 1 (CCL2, MCP-1) and superoxide dismutase (SOD 2), as well as the LPS-mediated decrease of apolipoprotein E (Apo E) in primary human monocytes from controls and T1D patients was determined.

RESULTS

CCL2 and IL-6 secretion in response to LPS was found significantly reduced in monocytes from T1D patients when compared to controls whereas basal CCL2 release was similar in control and T1D cells. In contrast, CXCL8 and apolipoprotein E secretion and SOD 2 expression upon LPS stimulation is similar from T1D and control monocytes.

CONCLUSION

These data indicate that LPS-mediated protein expression is only partly disturbed in monocytes from T1D patients. Reduced secretion of IL-6 and CCL2 in activated monocytes of these patients may contribute to an impaired inflammatory response and vascular disease.

Oral glycine administration attenuates diabetic complications in streptozotocin-induced diabetic rats

Diabetes mellitus is a disease characterized by impaired glucose metabolism that leads to retinopathy, brain micro-infarcts and other complications. We have previously shown that oral glycine administration to diabetic rats inhibits non-enzymatic glycation of hemoglobin and diminishes renal damage. In this work, we evaluated the capacity of the amino acid glycine (1% w/v, 130 mM) to attenuate diabetic complications in streptozotocin (STZ)-induced diabetic Wistar rats and compared them with non-treated or taurine-treated (0.5% w/v, 40 mM) diabetic rats. Glycine-treated diabetic rats showed an important diminution in the percentage of animals with opacity in lens and microaneurysms in the eyes. Interestingly, there was a diminished expression of O-acetyl sialic acid in brain vessels compared with untreated diabetic rats (P<0.05). Additionally, peripheral blood mononuclear cells isolated from glycine-treated diabetic rats showed a better proliferative response to PHA or ConA than those obtained from non-treated diabetic rats (P<0.05). Glycine-treated rats had a less intense corporal weight loss in comparison with non-treated animals. Our results suggest that administration of glycine attenuates the diabetic complications in the STZ-induced diabetic rat model, probably due to inhibition of the non-enzymatic glycation process.

Altered phenotype and function of dendritic cells in children with type 1 diabetes

The importance of dendritic cells (DC) in the activation of T cells and in the maintenance of self-tolerance is well known. We investigated whether alterations in phenotype and function of DC may contribute to the pathogenesis of Type 1 diabetes (T1DM). Mature DC (mDC) from 18 children with T1DM and 10 age-matched healthy children were tested. mDC, derived from peripheral blood monocytes cultured for 6 days in presence of interleukin (IL)-4 and granulocyte-macrophage colony stimulating factor (GM-CSF) and stimulated with lipopolysaccharide (LPS) for the last 24 h, were phenotyped for the expression of the co-stimulatory molecules B7.1 and B7.2. In six patients and six controls allogenic mixed leucocyte reaction (AMLR) was performed using mDC and cord blood-derived naive T cells at a DC/T naive ratio of 1 : 200. Proliferation was assessed on day 7 by [(3)H]-thymidine incorporation assay. Mature DC derived from patients showed, compared with controls, a reduced expression of B7.1 [mean of fluorescence intensity (MFI): 36.2 +/- 14.3 versus 72.9 +/- 34.5; P = 0.004] and B7.2 (MFI: 122.7 +/- 67.5 versus 259.6 +/- 154.1; P = 0.02). We did not find differences in the HLA-DR expression (P = 0.07). Moreover, proliferative response of allogenic naive T cells cultured with mDC was impaired in the patients (13471 +/- 9917.2 versus 40976 +/- 24527.2 cpm, P = 0.04). We also measured IL-10 and IL-12 concentration in the supernatant of DC cultures. Interestingly, we observed in the patients a sevenfold higher level of IL-10 (P = 0.07) and a ninefold lower level of IL-12 (P = 0.01). Our data show a defect in the expression of the co-stimulatory molecules and an impairment of DC priming function, events that might contribute to T1DM pathogenesis.

Poor in vitro maturation and pro-inflammatory cytokine response of dendritic cells in children at genetic risk of type 1 diabetes

Type 1 diabetes (T1D) has been associated with an aberrant maturation of dendritic cells (DC). We studied the maturation of monocyte-derived DC in children with newly diagnosed T1D and in healthy children with genetic risk for T1D. Peripheral blood monocytes from children with newly diagnosed T1D (n = 12; mean age 13.2 years), children with human leukocyte antigen (HLA)-risk genotype of T1D (n = 7; mean age 12.7 years) and healthy children (n = 14; mean age 11.2 years) were in vitro differentiated into DC. Expression of HLA-DR, CD80/86 and CD11c and secretion of interleukin (IL)-12, tumor necrosis factor (TNF)-alpha, IL-6 and IL-10 were measured using flow cytometry. Lower percentage of DC expressed CD11c and HLA-DR, and decreased production of TNF-alpha was found in children with newly diagnosed T1D and in children at genetic risk when compared to healthy children. Children with risk genotype also had decreased IL-12 production by DC. Children with T1D and children at genetic risk of T1D appear to have similar aberrancies in the maturation of DC, which may predispose to beta-cell autoimmunity.