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

Effects of Gut Microbiome Modulation on Reducing Adverse Health Outcomes among Elderly and Diabetes Patients during the COVID-19 Pandemic: A Randomised, Double-Blind, Placebo-Controlled Trial (IMPACT Study)

Gut microbiota is believed to be a major determinant of health outcomes. We hypothesised that a novel oral microbiome formula (SIM01) can reduce the risk of adverse health outcomes in at-risk subjects during the coronavirus disease 2019 (COVID-19) pandemic. In this single-centre, double-blind, randomised, placebo-controlled trial, we recruited subjects aged ≥65 years or with type two diabetes mellitus. Eligible subjects were randomised in a 1:1 ratio to receive three months of SIM01 or placebo (vitamin C) within one week of the first COVID-19 vaccine dose. Both the researchers and participants were blinded to the groups allocated. The rate of adverse health outcomes was significantly lower in the SIM01 group than the placebo at one month (6 [2.9%] vs. 25 [12.6], p < 0.001) and three months (0 vs. 5 [3.1%], p = 0.025). At three months, more subjects who received SIM01 than the placebo reported better sleep quality (53 [41.4%] vs. 22 [19.3%], p < 0.001), improved skin condition (18 [14.1%] vs. 8 [7.0%], p = 0.043), and better mood (27 [21.2%] vs. 13 [11.4%], p = 0.043). Subjects who received SIM01 showed a significant increase in beneficial Bifidobacteria and butyrate-producing bacteria in faecal samples and strengthened the microbial ecology network. SIM01 reduced adverse health outcomes and restored gut dysbiosis in elderly and diabetes patients during the COVID-19 pandemic.

Shared genetic architecture between type 2 diabetes and COVID-19 severity

PURPOSE

Patients with type 2 diabetes (T2D) have demonstrated a higher risk for developing more severe cases of COVID-19, but the complex genetic mechanism between them is still unknown. The aim of the present study was to untangle this relationship using genetically based approaches.

METHODS

By leveraging large-scale genome-wide association study (GWAS) summary statistics of T2D and COVID-19 severity, linkage disequilibrium score regression and Mendelian randomization (MR) analyses were utilized to quantify the genetic correlations and causal relationships between the two traits. Gene-based association and enrichment analysis were further applied to identify putative functional pathways shared between T2D and COVID-19 severity.

RESULTS

Significant, moderate genetic correlations were detected between T2D and COVID-19 hospitalization (r_g = 0.156, SE = 0.057, p = 0.005) or severe disease (r_g = 0.155, SE = 0.057, p = 0.006). MR analysis did not support evidence for a causal effect of T2D on COVID-19 hospitalization (OR 1.030, 95% CI 0.979, 1.084, p = 0.259) or severe disease (OR 0.999, 95% CI 0.934, 1.069, p = 0.982). Genes having p_gene < 0.05 for both T2D and COVID-19 severe were significantly enriched for biological pathways, such as response to type I interferon, glutathione derivative metabolic process and glutathione derivative biosynthetic process.

CONCLUSIONS

Our findings further confirm the comorbidity of T2D and COVID-19 severity, but a non-causal impact of T2D on severe COVID-19. Shared genetically modulated molecular mechanisms underlying the co-occurrence of the two disorders are crucial for identifying therapeutic targets.

Geriatric Health Care During the COVID-19 Pandemic: Managing the Health Crisis

COVID-19 pandemic significantly threatens the health and well-being of older adults. Aging-related changes, including multimorbidity, weakened immunity and frailty, may make older people more susceptible to severe infection and place them at higher risk of morbidity and mortality from COVID-19. Various quarantine measures have been implemented to control the spread of COVID-19. Nevertheless, such social distancing has disrupted routine health care practices, such as accessibility of medical services and long-term continuous care services. The medical management of older adults with multimorbidity is significantly afflicted by COVID-19. Older persons with frailty or multiple chronic disease may poorly adapt to the altered health care system, having detrimental consequences on their physical and mental health. COVID-19 pandemic has posed great challenges to the health of older adults. We highlighted the difficulties and obstacles of older adults during this unprecedented time. Also, we provided potential strategies and recommendations for actions to mitigate the COVID-19 pandemic threats. Certain strategies like community primary health care, medication delivery and home care support are adopted by many health facilities and caregivers, whereas other services such as internet hospital and virtual medical care are promoted to be accessible in many regions. However, guidelines and policies based on high-quality data are still needed for better health promotion of older groups with increasing resilience during the COVID-19 pandemic.

The Impact of Angiotensin-Converting Enzyme-2/Angiotensin 1-7 Axis in Establishing Severe COVID-19 Consequences

The COVID-19 pandemic has put a tremendous stress on the medical community over the last two years. Managing the infection proved a lot more difficult after several research communities started to recognize the long-term effects of this disease. The cellular receptor for the virus was identified as angiotensin-converting enzyme-2 (ACE2), a molecule responsible for a wide array of processes, broadly variable amongst different organs. Angiotensin (Ang) 1-7 is the product of Ang II, a decaying reaction catalysed by ACE2. The effects observed after altering the level of ACE2 are essentially related to the variation of Ang 1-7. The renin-angiotensin-aldosterone system (RAAS) is comprised of two main branches, with ACE2 representing a crucial component of the protective part of the complex. The ACE2/Ang (1-7) axis is well represented in the testis, heart, brain, kidney, and intestine. Infection with the novel SARS-CoV-2 virus determines downregulation of ACE2 and interrupts the equilibrium between ACE and ACE2 in these organs. In this review, we highlight the link between the local effects of RAAS and the consequences of COVID-19 infection as they arise from observational studies.

Association of high SARS-CoV-2 RNAemia with diabetes and mortality in COVID-19 critically ill patient

It has been suggested that during the period of respiratory worsening of severe COVID-19 patients, viral replication plays a less important role than inflammation. Using the droplet-based digital PCR (ddPCR) for precise quantification of plasma SARS-CoV-2 viral load (SARS-CoV-2 RNAemia), we investigated the relationship between plasma viral load, comorbidities, and mortality of 122 critically ill COVID-19 patients. SARS-CoV-2 RNAemia was detected by ddPCR in 90 (74%) patients, ranging from 70 to 213,152 copies per mL. A high (>1 000 copies/ml) or very high (>10,000 copies/ml) SARS-Cov-2 RNAemia was observed in 46 patients (38%), of which 26 were diabetic. Diabetes was independently associated with a higher SARS-CoV-2 RNAemia. In multivariable logistic regression models, SARS-CoV-2 RNAemia was strongly and independently associated with day-60 mortality. Early initiation of antiviral therapies might be considered in COVID-19 critically ill patients with high RNAemia.

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Plasma SARS-CoV-2 RNA was detected in 90 of 122 COVID-19 critically ill patients

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Plasma SARS-CoV-2 RNA was high (>1000 copies per mL) in 46 patients

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Diabetic patients had significantly higher levels of plasma SARS-CoV-2 RNA

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Plasma SARS-CoV-2 RNA levels were independently associated with day-60 mortality

Immunometabolic bases of type 2 diabetes in the severity of COVID-19

The outbreak of coronavirus disease 2019 (COVID-19) is caused by the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). COVID-19 and type 2 diabetes (T2D) have now merged into an ongoing global syndemic that is threatening the lives of millions of people around the globe. For this reason, there is a deep need to understand the immunometabolic bases of the main etiological factors of T2D that affect the severity of COVID-19. Here, we discuss how hyperglycemia contributes to the cytokine storm commonly associated with COVID-19 by stimulating monocytes and macrophages to produce interleukin IL-1β, IL-6, and TNF-α in the airway epithelium. The main mechanisms through which hyperglycemia promotes reactive oxygen species release, inhibition of T cell activation, and neutrophil extracellular traps in the lungs of patients with severe SARS-CoV-2 infection are also studied. We further examine the molecular mechanisms by which proinflammatory cytokines induce insulin resistance, and their deleterious effects on pancreatic β-cell exhaustion in T2D patients critically ill with COVID-19. We address the effect of excess glucose on advanced glycation end product (AGE) formation and the role of AGEs in perpetuating pneumonia and acute respiratory distress syndrome. Finally, we discuss the contribution of preexisting endothelial dysfunction secondary to diabetes in the development of neutrophil trafficking, vascular leaking, and thrombotic events in patients with severe SARS-CoV-2 infection. As we outline here, T2D acts in synergy with SARS-CoV-2 infection to increase the progression, severity, and mortality of COVID-19. We think a better understanding of the T2D-related immunometabolic factors that contribute to exacerbate the severity of COVID-19 will improve our ability to identify patients with high mortality risk and prevent adverse outcomes.

Diabetes Induces a Transcriptional Signature in Bone Marrow-Derived CD34+ Hematopoietic Stem Cells Predictive of Their Progeny Dysfunction

Hematopoietic stem/progenitor cells (HSPCs) participate in cardiovascular (CV) homeostasis and generate different types of blood cells including lymphoid and myeloid cells. Diabetes mellitus (DM) is characterized by chronic increase of pro-inflammatory mediators, which play an important role in the development of CV disease, and increased susceptibility to infections. Here, we aimed to evaluate the impact of DM on the transcriptional profile of HSPCs derived from bone marrow (BM). Total RNA of BM-derived CD34⁺ stem cells purified from sternal biopsies of patients undergoing coronary bypass surgery with or without DM (CAD and CAD-DM patients) was sequenced. The results evidenced 10566 expressed genes whose 79% were protein-coding genes, and 21% non-coding RNA. We identified 139 differentially expressed genes (p-value < 0.05 and |log2 FC| > 0.5) between the two comparing groups of CAD and CAD-DM patients. Gene Set Enrichment Analysis (GSEA), based on Gene Ontology biological processes (GO-BP) terms, led to the identification of fourteen overrepresented biological categories in CAD-DM samples. Most of the biological processes were related to lymphocyte activation, chemotaxis, peptidase activity, and innate immune response. Specifically, HSPCs from CAD-DM patients displayed reduced expression of genes coding for proteins regulating antibacterial and antivirus host defense as well as macrophage differentiation and lymphocyte emigration, proliferation, and differentiation. However, within the same biological processes, a consistent number of inflammatory genes coding for chemokines and cytokines were up-regulated. Our findings suggest that DM induces transcriptional alterations in HSPCs, which are potentially responsible of progeny dysfunction.

Factors leading to high morbidity and mortality of COVID-19 in patients with type 2 diabetes

Coronavirus disease 2019 (COVID-19) is a recent pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus. Diabetes (mostly type 2 diabetes mellitus, T2DM) and hyperglycemia are among the major comorbidities in patients with COVID-19 leading to poor outcomes. Reports show that patients with diabetes and COVID-19 are at an increased risk for developing severe complications including acute respiratory distress syndrome, multi-organ failure, and death. Here we explore potential mechanistic links that could explain the observed higher morbidity and mortality in this patient population. Patients with T2DM have an underlying increased level of inflammation associated with obesity and insulin resistance in addition to other comorbidities including hypertension, obesity, cardiovascular disease, dyslipidemia, and being older. We review evidence that T2DM with hyperglycemia are among factors that lead to elevated expression of angiotensin-converting enzyme 2 (ACE2) in lungs and other tissues; ACE2 is the cellular "receptor" and port of viral entry. The preexisting chronic inflammation with augmented inflammatory response to the infection and the increasing viral load leads to extreme systemic immune response ("cytokine storm") that is strongly associated with increased severity of COVID-19. Based on the available evidence, it is recommended by a panel of experts that safe but stringent control of blood glucose, blood pressure, and lipids be carried out in patients with T2DM, measures that could potentially serve to decrease the severity of COVID-19 should these patients contract the viral infection. Once the infection occurs, then attention should be directed to proper glycemic control with use of insulin and frequent monitoring of blood glucose levels.

COVID-19 and diabetes mellitus: implications for prognosis and clinical management

INTRODUCTION

COVID-19 is a novel coronavirus that emerged from Wuhan, China in December 2019, and within 3 months became a global pandemic.

AREAS COVERED

PubMed search of published data on COVID-19, respiratory infections, and diabetes mellitus (DM). DM associates with impairments of both cellular and humoral immunity. Early emergent global data reveal that severity of clinical outcome from COVID-19 infection (including hospitalization and admission to Intensive Care Unit [ICU]), associate with co-morbidities, prominently DM. The key principles of management of COVID-19 in patients with DM include ongoing focused outpatient management (remotely where necessary) and maintenance of good glycemic control.

EXPERT OPINION

We will remember the dawn of the third decade of the twenty-first century as a time when the world changed, the true scale and impact of which is hard for us to imagine. Like a phoenix from the ashes though, COVID-19 provides us with a great learning opportunity to renew insights into ourselves as individuals, our clinical teams, and the optimized provision of care for our patients. COVID-19 has re-shaped and re-focused our collective societal values, with a sea-changed shift from materialistic to human-centric, from self-centredness to altruism, ultimately for the betterment of patient care and the whole of society.

SARS-CoV-2 disease severity and diabetes: why the connection and what is to be done?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel virus responsible for the current coronavirus disease 2019 (COVID-19) pandemic, has infected over 3.5 million people all over the world since the first case was reported from Wuhan, China 5 months ago. As more epidemiological data regarding COVID-19 patients is acquired, factors that increase the severity of the infection are being identified and reported. One of the most consistent co-morbidities associated with worse outcome in COVID-19 patients is diabetes, along with age and cardiovascular disease. Studies on the association of diabetes with other acute respiratory infections, namely SARS, MERS, and Influenza, outline what seems to be an underlying factor in diabetic patients that makes them more susceptible to complications. In this review we summarize what we think may be the factors driving this pattern between diabetes, aging and poor outcomes in respiratory infections. We also review therapeutic considerations and strategies for treatment of COVID-19 in diabetic patients, and how the additional challenge of this co-morbidity requires attention to glucose homeostasis so as to achieve the best outcomes possible for patients.

Metformin-induced suppression of IFN-α via mTORC1 signalling following seasonal vaccination is associated with impaired antibody responses in type 2 diabetes

Diabetes mellitus (DM) patients are at an increased risk of complications following influenza-virus infection, seasonal vaccination (SV) is recommended. However, SV with trivalent influenza vaccine (TIV) can induce antibody and type-I interferon (IFN) responses, and the effect of anti-DM treatment on these responses is incompletely understood. We evaluated the antibody response and IFN-α expression in individuals with and without type 2 DM (T2DM) following SV, and examined the effects on anti-DM treatment. TIV elicited sero-protection in all groups, but antibody persistency was <8 months, except for the antibody response to B-antigens in non-DM. T2DM impaired the IgG avidity index, and T2DM showed a significantly decreased response against H1N1 and H3N2, in addition to delaying and reducing haemagglutination-inhibition persistency against influenza B-antigens in DM groups treated with metformin (Met-DM) or glibenclamide (GB-DM). Following TIV, the Met-DM and GB-DM groups exhibited reduced IFN-α expression upon stimulation with whole- and split-virion influenza vaccines. Suppression of IFN-α expression in the Met-DM group was associated with a reduction in the mechanistic target of rapamycin complex-1 pathway and impaired IgG avidity index. Thus, single-dose TIV each year might not be suitable for T2DM. Our data could aid the development of an efficacious influenza vaccine for T2DM.

Overexpression of microRNA-216a-3p Accelerates the Inflammatory Response in Cardiomyocytes in Type 2 Diabetes Mellitus by Targeting IFN-α2

Background: Type 2 diabetes mellitus (T2DM) is a chronic, hyperglycemia-associated, metabolic disorder. Heart disease is a major complication of T2DM. The present study aimed to explore the effects of miR-216a-3p on cardiomyocyte proliferation, apoptosis, and inflammation in T2DM through the Toll-like receptor (TLR) pathway involving interferon-α2 (IFN-α2) mediation. Methods: T2DM was induced in rats by a high-fat diet, in combination with an intraperitoneal injection of low-dose streptozotocin. ELISAs were conducted to measure inflammatory-related factors in serum. Next, isolated cardiomyocytes were used in loss- and gain-of-function experiments, followed by MTT and flow cytometry assays, conducted to evaluate cell proliferation, cell cycle, and apoptosis. Results: Our results revealed an increase in the inflammatory response in T2DM rat models, accompanied by significantly increased expression of miR-216a-3p and TLR pathway-related genes. However, a decrease in the expression of IFN-α2 was observed. Moreover, the presence of an miR-216a-3p inhibitor and si-IFN-α2 increased the expression of TLR pathway-related genes and cell apoptosis, whereas cell proliferation was significantly decreased in the cardiomyocytes. Conclusion: We found that in T2DM, miR-216a-3p inhibited the proliferation and enhanced the apoptosis of cardiomyocytes and generated an inflammatory response through activation of the TLR pathway and targeting of IFN-α2.

Functional status of immune cells in patients with long-lasting type 2 diabetes mellitus

Although patients with diabetes contract infectious diseases at higher frequencies, and in more severe forms, compared to non-diabetics, the underlying defects of the immune function have not been defined clearly. To address this, we designed an immune monitoring protocol and analysed the functional status of various immune cells. Peripheral blood mononuclear cells (PBMCs) were stimulated with the proper ligands and the functional reactivity of each lineage of cells was subsequently measured. Patients with type 2 diabetes mellitus (T2DM) had PBMC composition ratios comparable to healthy controls, except for a higher frequency of B cell and effector T cell fractions. The capacity of myeloid cells to secrete proinflammatory cytokines was not diminished in terms of the sensitivity and magnitude of the response. Furthermore, cytolytic activity and interferon (IFN)-γ production of natural killer (NK) cells and CD8⁺ T cells were not decreased in T2DM patients. Phenotypical maturation of dendritic cells, indicated by the up-regulation of major histocompatibility complex (MHC) proteins and co-stimulatory molecules in response to lipopolysaccharide (LPS), was slightly enhanced in T2DM patients. Finally, the functional differentiation profiles of CD4⁺ T cells did not differ between T2DM patients and the control group. These data indicate that patients with long-lasting T2DM do not have any gross functional defects in immune cells, at least in circulating monocytes, dendritic cells, NK cells and T lymphocytes.

Is the recent increment in attributable deaths to type-2 diabetes (T2D) associated with the latest chikungunya outbreak in a major epidemic area in Brazil?

INTRODUCTION

Chikungunya virus (CHIKV) can negatively influence outcomes in patients with pre-existing conditions. We investigated the association between the recent CHIKV outbreak and increased type 2 diabetes (T2D)-attributable deaths.

METHODS

Monthly averages of T2D-attributable deaths between 2001 and 2016 were determined and compared to the equivalent data for 2017 and the recent CHIKV outbreak.

RESULTS

CHKV outbreak peaked in April 2017 with 4,394.4 cases/100,000 inhabitants, while T2D-attributable deaths in the same period increased by 35.2%.

CONCLUSIONS

T2D-attributable deaths significantly increased compared to the previous data, which overlapped with CHIKV incidence. The pathophysiology of this association warrants further investigations.

Impaired Inflammatory Response to LPS in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a severe health problem worldwide, reaching epidemic levels. High susceptibility to infections of T2DM patients indicates dysregulated immune responses to pathogens. However, innate immune responses, including monocyte functions, in T2DM are poorly investigated. Therefore, in this study we aimed to assess lipopolysaccharide- (LPS-) induced immune responses of circulating monocytes from T2DM patients. The results showed that monocytes from T2DM were hyporesponsive to LPS challenge as reflected by significantly suppressed secretion of TNFα (p < 0.01) and expression of CD11b (p < 0.001) and TLR4 (p < 0.001) compared to those in monocytes from healthy subjects. Furthermore, LPS-induced IL-10 levels were similar in diabetic and healthy supernatants, while expression levels of CD163 were found to be downregulated on monocytes from T2DM (p < 0.001) suggesting impaired ability of monocytes to switch their phenotype to anti-inflammatory. Taken together, our results suggest compromised function of monocytes in T2DM, which may explain, at least partly, high incidence of infection in these patients.

Chikungunya and diabetes, what do we know?

BACKGROUND

Chikungunya (CHIK) is a viral disease transmitted by mosquitoes. The first cases in Brazil were confirmed in 2014. Between 2016 and 2017, over 300,000 cases were identified during this period, with nearly 300 deaths. The clinical manifestations, pathogenesis and risk factors for occurrence of severe cases are not yet well understood, although it is known that the severity of the cases is associated with the presence of comorbidities, especially diabetes mellitus (DM).

OBJECTIVE

To review the medical literature for the associations between DM and CHIK and to understand the potential impact on metabolic state and its complications.

METHODS

Literature review was carried out to search for articles (English, Portuguese and Spanish) in Medline and Virtual Health Library databases for the period between 1952 and 2017, with the following keywords: "Chikungunya fever", "Chikungunya virus", "diabetes mellitus", "diabetes", "diabetes complications "and "multi-morbidities (MeSH) "with interposition of the Boolean operator "AND".

RESULTS

After removal of duplicities and following exclusion criteria, 11 articles were selected. Our results showed that the patients of CHIK with DM had more severe and prolonged symptoms of CHIK and more frequently required hospitalization. No study investigated the biological process to explain how hyperglycemic state worsened the clinical manifestations of Chikungunya in diabetic patients.

CONCLUSION

An important association between DM and the severity of CHIK is observed. Prospective and more rigorous controlled studies are required to generate evidence that might y elucidate the causes of this relationship. Given the fast expanding viral infection of Chikungunya in Central and South America, Asia and Africa in recent years in the context of exponential increase in diabetes globally, the issue deserves global attention.

Deficiency in plasmacytoid dendritic cells and type I interferon signalling prevents diet-induced obesity and insulin resistance in mice

AIMS/HYPOTHESIS

Obesity is associated with glucose intolerance and insulin resistance and is closely linked to the increasing prevalence of type 2 diabetes. In mouse models of diet-induced obesity (DIO) and type 2 diabetes, an increased fat intake results in adipose tissue expansion and the secretion of proinflammatory cytokines. The innate immune system not only plays a crucial role in obesity-associated chronic low-grade inflammation but it is also proposed to play a role in modulating energy metabolism. However, little is known about how the modulation of metabolism by the immune system may promote increased adiposity in the early stages of increased dietary intake. Here we aimed to define the role of type I IFNs in DIO and insulin resistance.

METHODS

Mice lacking the receptor for IFN-α (IFNAR^-/-) and deficient in plasmacytoid dendritic cells (pDCs) (B6.E2-2 ^fl/fl .Itgax-cre) were fed a diet with a high fat content or normal chow. The mice were analysed in vivo and in vitro using cellular, biochemical and molecular approaches.

RESULTS

We found that the development of obesity was inhibited by an inability to respond to type I IFNs. Furthermore, the development of obesity and insulin resistance in this model was associated with pDC recruitment to the fatty tissues and liver of obese mice (a 4.3-fold and 2.7-fold increase, respectively). Finally, we demonstrated that the depletion of pDCs protects mice from DIO and from developing obesity-associated metabolic complications.

CONCLUSIONS/INTERPRETATION

Our results provide genetic evidence that pDCs, via type I IFNs, regulate energy metabolism and promote the development of obesity.

Benefits of flu vaccination for persons with diabetes mellitus: A review

Diabetes mellitus imposes a significant and increasing burden on society, with major consequences for human health, welfare and the economy worldwide. Persons with diabetes mellitus are at increased risk of developing severe complications after influenza virus infection and guidelines advise vaccination. The present evidence for influenza vaccine effectiveness in persons with diabetes mellitus is mainly based on observational studies with clinical endpoints like hospitalization and death, indicating a beneficial reduction of morbidity and mortality. Further supportive evidence comes from serological studies, in which persons with diabetes mellitus usually develop similar antibody levels after vaccination as healthy people. Observational studies may be prone to selection bias, and serological studies may not completely mirror vaccine effectiveness in the field. Although more controlled trials in persons with diabetes mellitus with laboratory-confirmed, influenza-specific outcomes would be desirable to better estimate the effect of vaccination, the currently available data justify routine influenza vaccination in persons with diabetes mellitus. As in this risk group, the use of influenza vaccine is far below target worldwide, efforts should be made to increase vaccination coverage.

Tim-3 is a Marker of Plasmacytoid Dendritic Cell Dysfunction during HIV Infection and Is Associated with the Recruitment of IRF7 and p85 into Lysosomes and with the Submembrane Displacement of TLR9

In chronic diseases, such as HIV infection, plasmacytoid dendritic cells (pDCs) are rendered dysfunctional, as measured by their decreased capacity to produce IFN-α. In this study, we identified elevated levels of T cell Ig and mucin-domain containing molecule-3 (Tim-3)-expressing pDCs in the blood of HIV-infected donors. The frequency of Tim-3-expressing pDCs correlated inversely with CD4 T cell counts and positively with HIV viral loads. A lower frequency of pDCs expressing Tim-3 produced IFN-α or TNF-α in response to the TLR7 agonists imiquimod and Sendai virus and to the TLR9 agonist CpG. Thus, Tim-3 may serve as a biomarker of pDC dysfunction in HIV infection. The source and function of Tim-3 was investigated on enriched pDC populations from donors not infected with HIV. Tim-3 induction was achieved in response to viral and artificial stimuli, as well as exogenous IFN-α, and was PI3K dependent. Potent pDC-activating stimuli, such as CpG, imiquimod, and Sendai virus, induced the most Tim-3 expression and subsequent dysfunction. Small interfering RNA knockdown of Tim-3 increased IFN-α secretion in response to activation. Intracellular Tim-3, as measured by confocal microscopy, was dispersed throughout the cytoplasm prior to activation. Postactivation, Tim-3 accumulated at the plasma membrane and associated with disrupted TLR9 at the submembrane. Tim-3-expressing pDCs had reduced IRF7 levels. Furthermore, intracellular Tim-3 colocalized with p85 and IRF7 within LAMP1⁺ lysosomes, suggestive of a role in degradation. We conclude that Tim-3 is a biomarker of dysfunctional pDCs and may negatively regulate IFN-α, possibly through interference with TLR signaling and recruitment of IRF7 and p85 into lysosomes, enhancing their degradation.

Chikungunya Virus Infection and Diabetes Mellitus: A Double Negative Impact

The impact of chikungunya virus (CHIKV) infection on diabetic patients (DPs) has not been described. We aimed to compare clinical features of CHIKV infection in DPs and nondiabetic patients (NDPs), and to evaluate its effects on glycemic control among DPs. We recorded clinical information and, in DPs, glycemic control. Forty-six DPs and 53 NDPs aged ≥ 20 years living in Haiti, with acute CHIKV infection, were studied. Diabetes duration was 7.1 ± 6.1 years. The most common acute CHIKV clinical manifestations were arthralgia (100.0% DPs and 98.1% NDPs, P = 1.000) and fever (86.9% DPs and 90.5% NDPs, P = 0.750). In DPs as compared with NDPs, arthralgia was more intense (mean pain score of 6.0/10 ± 2.2 versus 5.1/10 ± 2.0, P = 0.04) and took longer to improve (8.2 ± 3.0 versus 3.5 ± 2.5 days, P < 0.0001). Severe arthralgia was more prevalent (58.7% versus 20.8%, P = 0.0002), as was myalgia (80.4% versus 50.9%, P = 0.003), and fever lasted longer (5.1 ± 1.8 versus 3.7 ± 1.7 days, P = 0.0002). Among DPs, median fasting capillary glucose before versus after disease onset was 132.5 and 167.5 mg/dL (P < 0.001), corresponding to a median increase of 26.8% (interquartile range: 14.4-50.1%). Antidiabetic medication was titrated up in 41.3%. In summary, among DPs, CHIKV infection has a significant negative impact on glycemic control and, compared with NDPs, results in greater morbidity. Close clinical and glycemic observation is recommended in DPs with CHIKV infection.

Enterovirus-infected β-cells induce distinct response patterns in BDCA1+ and BDCA3+ human dendritic cells

Enteroviruses often cause mild disease, yet are also linked to development of autoimmune diabetes. Dendritic cells (DCs) shape both innate and adaptive immune responses, including anti-viral responses. How different human DC subsets shape anti-viral responses, whether they have complementary or overlapping functions and how this relates to autoimmune responses is largely unknown. We used enterovirus-infected β-cells and freshly isolated human myeloid DC (mDC) subsets as a model for autoimmune type 1 diabetes. Our data show that both the BDCA1⁺ and BDCA3⁺ mDC subsets engulf mock- as well as virus-infected β-cells, albeit BDCA1⁺ mDCs are more efficient. Uptake of enterovirus-infected, but not mock-infected cells, activated both DC subsets as indicated by the induction of co-stimulatory molecules and secretion of type I and type III interferons. Both subsets produced similar amounts of interferon-α, yet the BDCA3⁺ DC were superior in IFN-λ production. The BDCA1⁺ mDCs more strongly upregulated PD-L1, and were superior in IL-12 and IL-10 production as compared to the BDCA3⁺ DC. Despite lack of IL-12 production by the BDCA3+ DC, both BDCA1⁺ and BDCA3⁺ DCs activated T cells in allogeneic mixed lymphocyte reaction towards a Th1-type reactivity while suppressing Th2-associated cytokines.

Reduced interferon-α production by dendritic cells in type 1 diabetes does not impair immunity to influenza virus

The increased risk and persistence of infections in diabetic condition is probably associated with defects in the cellular immune responses. We have previously shown a decrease in the production of interferon (IFN)-α by dendritic cells (DCs) in diabetic subjects. The basal level of IFN-α in splenic plasmacytoid DCs (pDCs) is also lower in non-obese diabetic (NOD) mice compared to prediabetic mice. The objective of this study was to analyse the ability of diabetic mice to mobilize innate and CD8(+) T cell-mediated immune response to influenza A virus (IAV) with the live influenza A/Puerto Rico/8/1934 H1N1 (PR8) strain or with its immunodominant CD8(+) T cell epitopes. We found that following immunization with IAV, the level of IFN-α in diabetic mice was increased to the level in prediabetic mice. Immunization of NOD mice with the immunodominant IAV PR8 peptide induced clonal expansion of IFN-γ-producing CD8(+) T cells similar to the response observed in prediabetic mice. Thus, diabetic and prediabetic NOD mice have a similar capacity for IFN-α and IFN-γ production by pDCs and CD8(+) T cells, respectively. Therefore, the DC-related immune defect in diabetic NOD mice does not impair their capacity to develop an effective immune response to IAV. Our results suggest that reduced IFN-α production by diabetic human and mouse DCs is not an impediment to an effective immunity to IAV in type 1 diabetic subjects vaccinated with live attenuated influenza vaccine.

Cell-based interventions to halt autoimmunity in type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) results from death of insulin-secreting β cells mediated by self-immune cells, and the consequent inability of the body to maintain insulin levels for appropriate glucose homeostasis. Probably initiated by environmental factors, this disease takes place in genetically predisposed individuals. Given the autoimmune nature of T1DM, therapeutics targeting immune cells involved in disease progress have been explored over the last decade. Several high-cost trials have been attempted to prevent and/or reverse T1DM. Although a definitive solution to cure T1DM is not yet available, a large amount of information about its nature and development has contributed greatly to both the improvement of patient's health care and design of new treatments. In this study, we discuss the role of different types of immune cells involved in T1DM pathogenesis and their therapeutic potential as targets and/or modified tools to treat patients. Recently, encouraging results and new approaches to sustain remnant β cell mass and to increase β cell proliferation by different cell-based means have emerged. Results coming from ongoing clinical trials employing cell therapy designed to arrest T1DM will probably proliferate in the next few years. Strategies under consideration include infusion of several types of stem cells, dendritic cells and regulatory T cells, either manipulated genetically ex vivo or non-manipulated. Their use in combination approaches is another therapeutic alternative. Cell-based interventions, without undesirable side effects, directed to block the uncontrollable autoimmune response may become a clinical reality in the next few years for the treatment of patients with T1DM.

Immunobiology of beta-cell destruction

Type 1 diabetes is a chronic disease characterized by severe insulin deficiency and hyperglycemia, due to autoimmune destruction of pancreatic islets of Langerhans. A susceptible genetic background is necessary, but not sufficient, for the development of the disease. Epidemiological and clinical observations underscore the importance of environmental factors as triggers of type 1 diabetes, currently under investigation. Islet-specific autoantibodies precede clinical onset by months to years and are established tools for risk prediction, yet minor players in the pathogenesis of the disease. Many efforts have been made to elucidate disease-relevant defects in the key immune effectors of islet destruction, from the early failure of specific tolerance to the vicious circle of destructive insulitis. However, the events triggering islet autoimmunity as well as the transition to overt diabetes are still largely unknown, making prevention and treatment strategies still a challenge.

Circulating dendritic cell number and intracellular TNF-α production in women with type 2 diabetes

Human dendritic cell (DC) subsets perform specialized functions for surveillance against bacterial and viral infections essential for the management of type 2 diabetes (T2D). Production of tumor necrosis factor-alpha (TNF-α) by DCs acts in autocrine fashion to regulate DC maturation and promotes the inflammatory response. This study was designed to compare circulating DC number and intracellular TNF-α production between post-menopausal women with T2D and healthy women. Blood samples were obtained (n = 21/group) and examined for plasma glucose and TNF-α concentrations, and dendritic cell subset immunophenotype (plasmacytoid, pDC, CD85k(ILT-3)(+)CD123(+)CD16(-)CD14(-) and myeloid, mDC, CD85k(ILT-3)(+)CD33(+)CD123(dim to neg)CD16(-)CD14(dim to neg)). Intracellular production of TNF-α was determined in unstimulated and stimulated DCs. Women with T2D had significantly (P < 0.05) greater plasma glucose and TNF-α concentrations when compared to healthy women. Women with T2D having poor glycemic control (T2D Poor Control, HbA1c ≥ 7%) had fewer circulating pDCs than women with T2D having good glycemic control (T2D Good Control, HbA1c < 7%) and healthy women. A significant interaction (P = 0.011) was observed between the effects of plasma glucose and group for intracellular expression of TNF-α in stimulated pDCs. Intracellular production of TNF-α in pDCs was significantly greater in healthy vs. T2D Poor Control (P < 0.0001) and T2D Good Control (P < 0.0001) but did not differ between T2D subgroups. The mDC number and intracellular production of TNF-α did not differ between groups. These findings indicate that TNF-α production by pDCs was reduced in women with T2D and circulating number of pDCs was associated with glycemic control.

Negative regulatory responses to metabolically triggered inflammation impair renal epithelial immunity in diabetes mellitus

Diabetes mellitus is characterized by chronic inflammation and increased risk of infections, particularly of tissues exposed to the external environment. However, the causal molecular mechanisms that affect immune cells and their functions in diabetes are unclear. Here we show, by transcript and protein analyses, signatures of glucose-induced tissue damage, chronic inflammation, oxidative stress, and dysregulated expression of multiple inflammation- and immunity-related molecules in diabetic kidneys compared with non-diabetic controls. Abnormal signaling involving cytokines, G-protein coupled receptors, protein kinase C isoforms, mitogen-activated protein kinases, nuclear factor-κB (NFκB), and Toll-like receptors (TLR) were evident. These were accompanied by overexpression of negative regulators of NFκB, TLR, and other proinflammatory pathways, e.g., A20, SOCS1, IRAK-M, IκBα, Triad3A, Tollip, SIGIRR, and ST2L. Anti-inflammatory and immunomodulatory molecules, e.g., IL-10, IL-4, and TSLP that favor T_H2 responses were strongly induced. These molecular indicators of immune dysfunction led us to detect the cryptic presence of bacteria and human cytomegalovirus in more than one third of kidneys of diabetic subjects but none in non-diabetic kidneys. Similar signaling abnormalities could be induced in primary human renal tubular epithelial (but not mesangial) cell cultures exposed to high glucose, proinflammatory cytokines and methylglyoxal, and were reversed by combined pharmacological treatment with an antioxidant and a PKC inhibitor. Our results suggest that diabetes impairs epithelial immunity as a consequence of chronic and inappropriate activation of counter-regulatory immune responses, which are otherwise physiological protective mechanisms against inflammation. The immune abnormalities and cryptic renal infections described here may contribute to progression of diabetic nephropathy.

Altered phenotype of peripheral blood dendritic cells in pediatric type 1 diabetes

OBJECTIVE

Dendritic cells (DCs) are largely responsible for the activation and fine-tuning of T-cell responses. Altered numbers of blood DCs have been reported in type 1 diabetes (T1D). We aimed at characterizing the less well-known phenotypic properties of DCs in T1D.

RESEARCH DESIGN AND METHODS

In a case-control setting, samples from a total of 90 children were studied by flow cytometry or by quantitative real-time PCR (qPCR).

RESULTS

We found decreased numbers of myeloid DCs (mDCs) (8.97 vs. 13.4 cells/μL, P = 0.009, n = 31) and plasmacytoid DCs (pDCs) (9.47 vs. 14.6 cells/μL, P = 0.018, n = 30) in recent-onset T1D. Using a panel of antibodies against functionally important DC markers, we detected a decreased expression of CC chemokine receptor 2 (CCR2) on mDCs (percentage above negative control, P = 0.002, n = 29) and pDCs (median intensity, P = 0.003, n = 30) from T1D patients. In an independent series of children, the reduced expression of CCR2 was confirmed by qPCR in isolated mDCs (P = 0.043, n = 20). Serum concentrations of CCR2 ligands monocyte chemotactic protein-1 and -3 did not differ between the groups. A trend for an enhanced responsiveness of the nuclear factor-κB pathway (P = 0.063, n = 39) was seen in mDCs from children with β-cell autoantibodies, which is possibly related to the reduced CCR2 expression, since CCR2 on mDCs was downregulated by nuclear factor-κB-activating agents.

CONCLUSIONS

Given the role of CCR2 in DC chemotaxis and in DC-elicited Th1 differentiation, our results may indicate a functionally important DC abnormality in T1D affecting the initiation and quality of immune responses.

Increased levels of serum granulocyte-macrophage colony-stimulating factor is associated with activated peripheral dendritic cells in type 2 diabetes subjects (CURES-99)

BACKGROUND

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pro-inflammatory cytokine with growth factor-like properties for monocytes and dendritic cells (DCs). In the present study, serum GM-CSF levels and the activation status of DCs were studied in type 2 diabetes mellitus (T2DM) subjects.

METHODS

Study subjects were recruited from the Chennai Urban Rural Epidemiology Study. Healthy controls (n=45) and T2DM patients (n=45) were included in the study. Serum levels of GM-CSF, interleukin-1β, interleukin-6, and tumor necrosis factor-α were measured. Enumeration of circulating DCs (myeloid [m] and plasmocytoid [p]) and its surface antigen expression were quantified by flow cytometry.

RESULTS

The serum GM-CSF levels were significantly higher among diabetes subjects compared with subjects without diabetes and showed a positive correlation with glycated hemoglobin (r=0.208, P=0.018). The serum GM-CSF levels were lower in subjects on combined insulin and oral hypoglycemic agents (OHA) treatment (1.09 pg/mL) compared with those taking OHA alone (1.9 pg/mL). The increased GM-CSF levels were associated with the activated phenotype of mDCs and pDCs, as determined by up-regulation of the lineage markers.

CONCLUSION

The activated state of mDCs and pDCs seen among diabetes subjects might be due to the increased levels of GM-CSF and other pro-inflammatory cytokines.

Altered Toll-like receptor signaling pathways in human type 1 diabetes

There is compelling evidence from animal models of type 1 diabetes (T1D) that the innate immune system plays a key role in early mechanisms triggering islet destruction. Very little is known, however, about innate immune subsets and pathways potentially involved in mechanisms leading to human T1D. The present study used a comprehensive approach to analyze innate immune functions in primary monocytes and dendritic cells (DCs) from newly diagnosed patients with T1D versus age-matched healthy individuals. We observed that incubation of PBMCs in the presence of the TLR7/8 agonist R848 led to increased proportion of plasmacytoid dendritic cells (pDCs) expressing IFN-α in patients versus healthy control subjects. We also found that TLR4 activation induced a higher frequency of IL-1β expressing monocytes and a reduction in the percentage of IL-6 expressing myeloid dendritic cells (mDCs). The altered TLR responsiveness was not due to aberrant proportions of peripheral DC subsets and monocytes in the blood and did not correlate with altered hemoglobin A1c and the expression of diabetes susceptibility genes but could potentially be associated with enhanced nuclear factor-kappa B signaling. Finally, we observed that levels of serum IFN-α2, IL-1β, IFN-γ, and CXCL-10 were elevated in new onset patients versus the control group. Taken together, our observations provide evidence that altered innate immunity exists in mDCs and pDCs from T1D and raise the possibility that these alterations may be associated with disease mechanisms.

Dendritic cell-based therapy in Type 1 diabetes mellitus

Dendritic cell (DC) immunotherapy is a clinical reality. Despite two decades of considerable data demonstrating the feasibility of using DCs to prolong transplant allograft survival and to prevent autoimmunity, only now are these cells entering clinical trials in humans. Type 1 diabetes is the first autoimmune disorder to be targeted for treatment in humans using autologous-engineered DCs. This review will highlight the role of DCs in autoimmunity and the manner in which they have been engineered to treat these disorders in rodent models, either via the induction of immune hyporesponsiveness, which may be cell- and/or antigen-specific, or indirectly by upregulation of other immune cell networks.

Multiplexed immunophenotyping of human antigen-presenting cells in whole blood by polychromatic flow cytometry

We describe two modular protocols for immunostaining and multiparameter flow cytometric analysis of major human antigen-presenting cells (APCs; e.g., dendritic cells, monocytes and B lymphocytes) in minimally manipulated whole blood samples. Simultaneous detection of up to eight colors is enabled by careful selection and testing of cell-subset-defining monoclonal antibodies (anchor markers) in the appropriate fluorochrome combinations, in order to show the quantification of surface expression levels of molecules involved in chemotaxis (e.g., CX(3)CR1 and CCR2), adhesion (e.g., CD11b and CD62L), antigen presentation (e.g., CD83, CD86 and CD209) and immune regulation (e.g., CD101) on circulating APCs. Each immunostaining reaction requires as little as 50-100 microl of peripheral whole blood and no density-gradient separation, and the entire procedure from preparation of reagents to flow cytometry can be completed in <5 h.

Toll-like receptors and type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease that results in the progressive loss of insulin producing cells. Studies performed in humans with T1D and animal models of the disease over the past two decades have suggested a key role for the adaptive immune system in disease mechanisms. The role of the innate immune system in triggering T1D was shown only recently. Research in this area was greatly facilitated by the discovery of toll-like receptors (TLRs) that were found to be a key component of the innate immune system that detect microbial infections and initiate antimicrobial host defense responses. New data indicate that in some situations, the innate immune system is associated with mechanisms triggering autoimmune diabetes. In fact, studies preformed in the BioBreeding Diabetes Resistant (BBDR) and LEW1.WR1 rat models of T1D demonstrate that virus infection leads to islet destruction via mechanisms that may involve TLR9-induced innate immune system activation. Data from these studies also show that TLR upregulation can synergize with virus infection to dramatically increase disease penetrance. Reports from murine models of T1D implicate both MyD88-dependent and MyD88-independent pathways in the course of disease. The new knowledge about the role of innate immune pathways in triggering islet destruction could lead to the discovery of new molecules that may be targeted for disease prevention.

Immunology of beta-cell destruction

The pancreatic islet beta-cells are the target for an autoimmune process that eventually results in an inability to control blood glucose due to the lack of insulin. The different steps that eventually lead to the complete loss of the beta-cells are reviewed to include the very first step of a triggering event that initiates the development of beta-cell autoimmunity to the last step of appearance of islet-cell autoantibodies, which may mark that insulitis is about to form. The observations that the initial beta-cell destruction by virus or other environmental factors triggers islet autoimmunity not in the islets but in the draining pancreatic lymph nodes are reviewed along with possible basic mechanisms of loss of tolerance to islet autoantigens. Once islet autoimmunity is established the question is how beta-cells are progressively killed by autoreactive lymphocytes which eventually results in chronic insulitis. Many of these series of events have been dissected in spontaneously diabetic mice or rats, but controlled clinical trials have shown that rodent observations are not always translated into mechanisms in humans. Attempts are therefore needed to clarify the step 1 triggering mechanisms and the step to chronic autoimmune insulitis to develop evidence-based treatment approaches to prevent type 1 diabetes.

Staphylococcus aureus nasal carriage might be associated with vitamin D receptor polymorphisms in type 1 diabetes

BACKGROUND

Polymorphisms in the vitamin D receptor (VDR) gene have been associated with susceptibility to several diseases, including type 1 diabetes (T1D) and infections. In this study we investigated whether VDR gene polymorphisms influence nasal carriage of Staphylococcus aureus in individuals with T1D.

METHODS

In 93 T1D patients, VDR polymorphisms on FokI F>f, BsmI B>b, ApaI A>a, and TaqI T>t were determined in DNA extracted from peripheral blood leukocytes, and a nasal swab was obtained to detect colonization by S. aureus. A repeat swab was obtained in 76/93 subjects for the estimation of persistent S. aureus carriage.

RESULTS

The prevalence of S. aureus nasal colonization was 31.2% and the prevalence of persistent carriage was 25%. The presence of TaqI T allele was related to higher rates of S. aureus colonization, and TaqI TT homozygotes were more colonized (48.5% vs. 21.7%; p 0.007; OR 3.40, 95% CI 1.36-8.52) and more persistent carriers (37.9% vs. 17.0%; p 0.039; OR 2.98, 95% CI 1.02-8.67). The presence of ApaI A allele was related to lower rates of S. aureus colonization, and ApaI AA homozygotes were less colonized (17.6% vs. 39.0%; p 0.026; OR 0.34, 95% CI 0.12-0.94) and less persistent carriers (11.5% vs. 32%; p 0.043; OR 0.28, 95% CI 0.07-1.06). No differences were observed for BsmI and FokI genotypes.

CONCLUSIONS

Our findings suggest that VDR polymorphisms may be associated with nasal carriage of S. aureus in individuals with T1D, and further contribute to the better understanding of the immunomodulatory role of vitamin D in the human host's response and susceptibility to infection.

Human cord blood stem cell-modulated regulatory T lymphocytes reverse the autoimmune-caused type 1 diabetes in nonobese diabetic (NOD) mice

Background

The deficit of pancreatic islet β cells caused by autoimmune destruction is a crucial issue in type 1 diabetes (T1D). It is essential to fundamentally control the autoimmunity for treatment of T1D. Regulatory T cells (Tregs) play a pivotal role in maintaining self-tolerance through their inhibitory impact on autoreactive effector T cells. An abnormality of Tregs is associated with initiation of progression of T1D.

Methodology/Principal Findings

Here, we report that treatment of established autoimmune-caused diabetes in NOD mice with purified autologous CD4⁺CD62L⁺ Tregs co-cultured with human cord blood stem cells (CB-SC) can eliminate hyperglycemia, promote islet β-cell regeneration to increase β-cell mass and insulin production, and reconstitute islet architecture. Correspondingly, treatment with CB-SC-modulated CD4⁺CD62L⁺ Tregs (mCD4CD62L Tregs) resulted in a marked reduction of insulitis, restored Th1/Th2 cytokine balance in blood, and induced apoptosis of infiltrated leukocytes in pancreatic islets.

Conclusions/Significance

These data demonstrate that treatment with mCD4CD62L Tregs can reverse overt diabetes, providing a novel strategy for the treatment of type 1 diabetes as well as other autoimmune diseases.

Plasmacytoid dendritic cells are proportionally expanded at diagnosis of type 1 diabetes and enhance islet autoantigen presentation to T-cells through immune complex capture

OBJECTIVE

Immune-mediated destruction of beta-cells resulting in type 1 diabetes involves activation of proinflammatory, islet autoreactive T-cells, a process under the control of dendritic cells of the innate immune system. We tested the hypothesis that type 1 diabetes development is associated with disturbance of blood dendritic cell subsets that could enhance islet-specific autoimmunity.

RESEARCH DESIGN AND METHODS

We examined blood dendritic cells (plasmacytoid and myeloid) in 40 patients with recent-onset diabetes (median duration 28 days) and matched control subjects. We also examined the relative ability of different dendritic cell subsets to process and present soluble or immune complexed islet cell autoantigen (the islet tyrosine phosphatase IA-2) to responder CD4 T-cells.

RESULTS

The balance of blood dendritic cells was profoundly disturbed at diabetes diagnosis, with a significantly elevated proportion of plasmacytoid and reduction of myeloid cells compared with control subjects. Dendritic cell subset distribution was normal in long-standing disease and in patients with type 2 diabetes. Both dendritic cell subsets processed and presented soluble IA-2 to CD4 T-cells after short-term culture, but only plasmacytoid dendritic cells enhanced (by as much as 100%) autoantigen presentation in the presence of IA-2(+) autoantibody patient serum.

CONCLUSIONS

The plasmacytoid subset of dendritic cells is overrepresented in the blood close to diabetes onset and shows a distinctive ability to capture islet autoantigenic immune complexes and enhance autoantigen-driven CD4 T-cell activation. This suggests a synergistic proinflammatory role for plasmacytoid dendritic cells and islet cell autoantibodies in type 1 diabetes.

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.

Innate immunity and its role in type 1 diabetes

PURPOSE OF REVIEW

Over the last 2 decades, studies addressing mechanisms of type 1 diabetes have focused primarily on the role of T lymphocytes in disease mechanisms. Recent investigations, however, suggest that the innate immune system plays a key role in promoting the response of autoreactive T cells triggering type 1 diabetes. The discovery of toll-like receptors in the 1990s has led to a better understanding of signaling pathways involved in initiating innate immune pathways and how these pathways may be associated with mechanisms leading to autoimmune disease. This review focuses on recent studies on the role of Toll-like receptors and innate pathways in triggering type 1 diabetes.

RECENT FINDINGS

Data from animal models of type 1 diabetes provide strong support to the hypothesis that Toll-like receptor-induced innate signaling pathways are involved in the proinflammatory process leading to autoimmune diabetes. Studies performed in peripheral blood cells and sera from patients with type 1 diabetes indicate that aberrant innate functions might exist in such patients, but the relevance of these alterations to the mechanism leading to type 1 diabetes is currently unclear.

SUMMARY

The discovery that innate signaling pathways are involved in the mechanism that may trigger islet inflammation and destruction holds great promise for the identification of new innate signaling molecules that could be targeted to specifically inhibit the autoimmune process to prevent autoimmune diabetes.

Influence of metabolic syndrome on the response of chronic hepatitis C to anti-viral therapy and its possible mechanism

Genotype and viral load have been found as the most important viral factors influencing antiviral response. Host factors include metabolic syndrome such as diabetes type 2, hepatocyte steatosis, and insulin resistance. Diabetes type 2 decreases the sustained response to interferon α, and hepatocyte steatosis impairs the sustained response rate in patients with HCV genotype 1, but not in genotype 3. Insulin resistance emerges as the most important host factors in the prediction of response in chronic hepatitis C patients with interferon plus ribavirin. Most studies showed that insulin resistance may induce interferon resistance by blocking intracellular signal pathway of interferon.

Immunomodulation of autoimmune diabetes by dendritic cells

The biology and properties of dendritic cells (DCs) have been intensely studied in the research areas of infectious diseases, tumor immunology, and vaccine development. This unique subset of immune cells has recently also moved to the center of interest for basic and clinical research in autoimmunity, owing not only to the extraordinary importance of DCs in the initiation and sustenance of adaptive immune responses, but also to more recent discoveries about their profound ability to control and downregulate ongoing T-cell responses. We review current progress of using DCs in mice for induction and propagation of autoimmune T-cell responses and their therapeutic potential to dampen or even stop beta-cell-specific autoimmunity. Finally, we offer our perspective on how basic research progress in DC technology, mostly from mouse models, may translate into emerging diagnostic and therapeutic applications for human type 1 diabetes.

Innate immunity, insulin resistance and type 2 diabetes

Recent evidence has disclosed previously unrecognized links among insulin resistance, obesity, circulating immune markers, immunogenetic susceptibility, macrophage function and chronic infection. Genetic variations leading to altered production or function of circulating innate immune proteins, cellular pattern-recognition receptors and inflammatory cytokines have been linked with insulin resistance, type 2 diabetes, obesity and atherosclerosis. Cellular innate immune associations with obesity and insulin resistance include increased white blood cell count and adipose tissue macrophage numbers. The innate immune response is modulated possibly by both predisposition (genetic or fetal programming), perhaps owing to evolutionary pressures caused by acute infections at the population level (pandemics), and chronic low exposure to environmental products or infectious agents. The common characteristics shared among innate immunity activation, obesity and insulin resistance are summarized.

Immunoregulatory dendritic cells to prevent and reverse new-onset Type 1 diabetes mellitus

Herein, the authors provide an overview of where dendritic cells lie in the immunopathology of autoimmune Type 1 diabetes mellitus and how dendritic cell-based therapy may be usefully translated to treat and reverse the disease. The immunopathology of Type 1 diabetes mellitus offers a number of windows at which immunotherapy can be applied to delay, stop and even reverse the autoimmune processes, especially in light of the recent antibody-based accomplishment of improvement in residual beta-cell mass function. As in almost all cell-specific inflammatory processes, dendritic cells are central regulators of diabetes onset and progression. This realisation, along with accumulating data confirming a role for dendritic cells in maintaining and inducing tolerance in multiple therapeutic settings, has prompted a line of investigation to identify the most effective embodiments of dendritic cells for diabetes immunotherapy.

The cross-regulatory relationship between human dendritic and regulatory T cells and its role in type 1 diabetes mellitus

Dendritic cells (DCs) and T regulatory (Treg) cells play a crucial role in maintaining the tolerance needed to prevent the onset of autoimmunity that leads to the development of type 1 diabetes mellitus (T1DM). Various experimental studies have shown that human DC subsets are involved in the induction of anergy in T cells and in the differentiation of conventional CD4(+) and CD8(+) lymphocytes into the respective subtypes of Treg cells. Treg cells, in turn, have been shown to modulate the function of DCs to exhibit tolerogenic properties. To evaluate whether T1DM development is related to abnormalities in DCs and Treg cells, many attempts have been made to characterize these cell types in diabetic individuals and in subjects at risk of developing the disease. This review aims to supply an update on the progress made in these aspects of T1DM research.

Decreased blood dendritic cell counts in type 1 diabetic children

In this study DC numbers, phenotype and DC responses to the Toll-like receptor (TLR)-3 ligand, poly I:C, were examined in new-onset Type 1 diabetes (T1D) patients (ND) and in established T1D patients (ED). Absolute blood myeloid DC (MDC) and plasmacytoid DC (PDC) numbers were decreased in ND and ED patients compared to age-matched controls. The decrease in MDC and PDC counts was less evident in patients with a combination of T1D and coeliac disease (CD) or CD alone. The age-dependent decline in blood DC numbers, found in control children, was not evident in ND patients, such that 2-10 years old ND children had similar MDC and PDC numbers to 15-17 years old controls. In ED patients the t-score of MDC and PDC numbers related to the age of diagnosis but not to disease duration. Blood DC in T1D patients were not distinguished from those of controls by the levels of HLA-DR, CD40 and CD86 expression or the percentage of DC expressing cytokines, IL-12, IL-10, IL-6 and TNF-alpha, in responses to poly I:C. If low DC numbers are shown to contribute to the autoimmunity in T1D, interventions aimed to increase DC numbers may mitigate against beta-cell loss.