The peripheral immune response in hyperglycemic stroke

Type 2 diabetes remodels collateral circulation and promotes leukocyte adhesion following ischemic stroke

Type 2 diabetes mellitus (T2DM) is associated with impaired leptomeningeal collateral compensation and poor stroke outcome. Neutrophils tethering and rolling on endothelium after stroke can also independently reduce flow velocity. However, the chronology and topological changes in collateral circulation in T2DM is not yet defined. Here, we describe the spatial and temporal blood flow dynamics and vessel remodeling in pial arteries and veins and leukocyte-endothelial adhesion following middle cerebral artery (MCA) stroke using two-photon microscopy in awake control and T2DM mice. Relative to control mice prior to stroke, T2DM mice already exhibited smaller pial vessels with reduced flow velocity. Following stroke, T2DM mice displayed persistently reduced blood flow in pial arteries and veins, resulting in a poor recovery of downstream penetrating arterial flow and a sustained deficit in microvascular flow. There was also persistent increase of leukocyte adhesion to the endothelium of veins, coincided with elevated neutrophils infiltration into brain parenchyma in T2DM mice compared to control mice after stroke. Our data suggest that T2DM-induced increase in chronic inflammation may contribute to the remodeling of leptomeningeal collateral circulation and the observed hemodynamics deficiency that potentiates poor stroke outcome.

The Role of Platelet Distribution Width in the Association Between Blood Glucose and Neurological Impairment Severity in Acute Ischemic Stroke: A Moderated Mediation Model

Objective

Fasting blood glucose (FBG) is a recognized risk factor for Ischemic Stroke, but little research has examined the interaction among FBG, Platelet Distribution Width (PDW) and the severity of neuronal damage. Thus, the present study constructs a moderated mediation model aimed to elucidate the relationships among FBG, PDW, and NIHSS scores in patients with acute ischemic stroke (AIS).

Methods

We conducted a cross-sectional study on 431 AIS patients. Upon hospital admission, we assessed the patients' NIHSS scores and collected blood samples to measure FBG and PDW levels. The relationship between FBG and NIHSS scores moderated by PDW was analyzed by linear curve fitting analysis, multiple linear regression analysis, and moderated mediation analysis respectively.

Results

In the tertile grouping based on FBG, both PDW and NIHSS scores of AIS patients demonstrated an increase corresponding with rising levels of FBG (p<0.001 for both). Multiple linear regression analysis revealed that, the β coefficients (95% CI) for the relationship between FBG and NIHSS scores were 1.49 (1.27-1.71, p<0.01) post-adjustment for potential confounders. The β coefficients (95% CI) for the relationship between FBG and PDW were 0.02 (0.01-0.04, p<0.01) post-adjustment. Likewise, for the relationship between PDW and NIHSS scores, the β coefficients (95% CI) were 4.33 (3.07-5.59, p<0.01) after adjustment. These positive association remained consistent in sensitivity analysis and hierarchical analysis. Smoothed plots suggested that there are linear relationships between FBG and PDW and NIHSS scores respectively. Further mediation analysis indicated that increased PDW significantly (p<0.01) mediated 5.91% of FBG-associated increased NIHSS scores.

Conclusion

This study suggested that FBG levels were associated with NIHSS scores, and the FBG-associated neurological impairment may be partially mediated by PDW. These findings underscore the importance of monitoring FBG and PDW levels in AIS patients, potentially guiding risk intervention strategies.

Disease Duration and Chronic Complications Associate With Immune Activation in Individuals With Longstanding Type 1 Diabetes

CONTEXT

Type 1 diabetes (T1D) is associated with alterations of the immune response which persist even after the autoimmunity aspect is resolved. Clinical factors that cause dysregulation, however, are not fully understood.

OBJECTIVE

To identify clinical factors that affect immune dysregulation in people with longstanding T1D.

DESIGN

In this cross-sectional study, 243 participants with longstanding T1D were recruited between February 2016 and June 2017 at the Radboudumc, the Netherlands. Blood was drawn to determine immune cell phenotype and functionality, as well as circulating inflammatory proteome. Multivariate linear regression was used to determine the association between glycated hemoglobin (HbA1c) levels, duration of diabetes, insulin need, and diabetes complications with inflammation.

RESULTS

HbA1c level is positively associated with circulating inflammatory markers (P < .05), but not with immune cell number and phenotype. Diabetes duration is associated with increased number of circulating immune cells (P < .05), inflammatory proteome (P < .05), and negatively associated with adaptive immune response against Mycobacterium tuberculosis and Rhizopus oryzae (P < .05). Diabetes nephropathy is associated with increased circulating immune cells (P < .05) and inflammatory markers (P < .05).

CONCLUSION

Disease duration and chronic complications associate with persistent alterations in the immune response of individuals with long standing T1D.

Acute Low Dose Naltrexone Increases β-Endorphin and Promotes Neuronal Recovery Following Hypoxia-Ischemic Stroke in Type-2 Diabetic Mice

Diabetic patients experience significant mortality and poor recovery following ischemic stroke. Our clinical and basic science studies demonstrate an overall immune suppression in the periphery of diabetic stroke patients, as well as within the central nervous system (CNS) of type-2 diabetic mice following hypoxia-ischemia (HI). Low doses of naltrexone (LDN) improved clinical outcomes in many autoimmune diseases by acting on opioid receptors to release β-endorphin which in turn balances inflammatory cytokines and modulates the opioid growth factor (OGF)-opioid growth factor receptor (OGFr) pathway. We hypothesized that in our model of diabetic mice, LDN treatment will induce the release of β-endorphin and improve CNS response by promoting neuronal recovery post HI. To test this hypothesis, we induced HI in 10 week old male db/db and db/ + mice, collected tissue at 24 and 72 h post HI, and measured OGF levels in plasma and brain tissue. The infarct size and number of OGF + neurons in the motor cortex, caudate and hippocampus (CA3) were measured. Following HI, db/db mice had significant increases in brain OGF expression, increased infarct size and neurological deficits, and loss of OGFr + neurons in several different brain regions. In the second experiment, we injected LDN (1 mg/kg) intraperitoneally into db/db and db/ + mice at 4, 24, and 48 h post HI, and collected brain tissue and blood at 72 h. Acute LDN treatment increased β-endorphin and OGF levels in plasma and promoted neuronal recovery in db/db mice compared to phosphate buffer saline (PBS)-treated diabetic mice suggesting a protective or regenerative effect of LDN.

The neutrophil-to-lymphocyte ratio is an important indicator correlated to early neurological deterioration in single subcortical infarct patients with diabetes

Background and purpose

This study aimed to investigate the relationship between neutrophil-to-lymphocyte ratio (NLR) and early neurological deterioration (END) among cases suffering from single subcortical infarction (SSI) and diabetes.

Methods

We collected the data of patients with SSI admitted to our hospital between January 2019 and December 2020 retrospectively. A score of ≥2 elevations in overall National Institutes of Health Stroke Scale (NIHSS) score or ≥1 increase in motor NIHSS score in 5-day post-admission was considered END. Furthermore, logistic regression was used to analyze the relationship between NLR and END among SSI cases.

Results

Altogether, we enrolled 235 consecutive SSI cases, of which 53 (22.5%) were diagnosed with END, while 93 (39.5%) were diabetic. In patients with diabetes, the value of NLR increased markedly among the patients with END (median, 3.59; IQR, 2.18–4.84) compared to patients without END (median, 2.64; IQR, 1.89–3.18; P = 0.032). Meanwhile, in patients without diabetes, NLR was not significantly associated with END. In the multivariate analysis, NLR values were positively related to END (adjusted odds ratio (OR), 1.768; 95% CI, 1.166–2.682, P = 0.007) upon adjusting age, SSI type, lesion diameter, initial NIHSS, fasting blood glucose (FBG), 2-h postprandial blood glucose (2hPBG), and estimated glomerular filtration rate (eGFR). The subgroup analysis showed that the relationship between NLR and END was more pronounced in the branch atheromatous disease (BAD) (adjusted OR, 1.819; 95% CI, 1.049–3.153, P = 0.033) and anterior SSI subgroups (adjusted OR, 2.102; 95% CI, 1.095–4.037, P = 0.026).

Conclusion

NLR value was significantly related to END among SSI patients with diabetes and was recognized as an independent factor in predicting the risk of END.

The effect of chronic exposure to metformin in a new type-2 diabetic NONcNZO10/LtJ mouse model of stroke

BACKGROUND

Diabetes is an independent risk factor of stroke and previous studies have confirmed that diabetic patients and animals experience poorer clinical outcomes following stroke. In this study, we aim to determine the effect of chronic exposure of the first-line antidiabetic agent, metformin, to restore euglycemia and to impact brain cell death following stroke in a new type-2 diabetes, NONcNZO10/LtJ (RCS-10) mouse model of stroke.

METHODS

Male RCS-10 mice received a moderate (11%) fat diet post-weaning, at 4 weeks of age, and became diabetic by 12-14 weeks, thus resembling human maturity-onset diabetes. The mice received either metformin or vehicle for 4 weeks before undergoing a hypoxic/ischemic (HI) insult. Blood samples were collected pre-, post-treatment, and post HI for glucose and lipid measurements, and brains were analyzed for infarct size, glial activation, neuronal cell death, and metformin-mediated adenosine monophosphate-activated protein kinase (AMPK) signaling at 48 h post HI.

RESULTS

Pretreatment with metformin maintained euglycemia for 4 weeks but did not change body weight or lipid profile. Metformin treatment significantly enhanced the microglial Bfl-1 mRNA expression and showed a non-significant increase in GFAP mRNA, however, GFAP protein levels were reduced. Metformin treatment slightly increased neuronal NeuN and MAP-2 protein levels and significantly reduced overall mortality post HI but did not elicit any significant change in infarct size.

CONCLUSION

The study suggests that the prolonged effect of metformin-induced euglycemia promoted the microglial activation, reduced neuronal cell death, and improved the overall survival following stroke, without any change in infarct size.

Endangered Lymphocytes: The Effects of Alloxan and Streptozotocin on Immune Cells in Type 1 Induced Diabetes

Alloxan (ALX) and streptozotocin (STZ) are extensively used to induce type 1 diabetes (T1D) in animal models. This study is aimed at evaluating the differences in immune parameters caused by ALX and STZ. T1D was induced either with ALX or with STZ, and the animals were followed for up to 180 days. Both ALX and STZ induced a decrease in the total number of circulating leukocytes and lymphocytes, with an increase in granulocytes when compared to control mice (CT). STZ-treated mice also exhibited an increase in neutrophils and a reduction in the lymphocyte percentage in the bone marrow. In addition, while the STZ-treated group showed a decrease in total CD3+, CD4-CD8+, and CD4+CD8+ T lymphocytes in the thymus and CD19+ B lymphocytes in the pancreas and spleen, the ALX group showed an increase in CD4-CD8+ and CD19+ only in the thymus. Basal levels of splenic interleukin- (IL-) 1β and pancreatic IL-6 in the STZ group were decreased. Both diabetic groups showed atrophy of the thymic medulla and degeneration of pancreatic islets of Langerhans composed of inflammatory infiltration and hyperemia with vasodilation. ALX-treated mice showed a decrease in reticuloendothelial cells, enhanced lymphocyte/thymocyte cell death, and increased number of Hassall's corpuscles. Reduced in vitro activation of splenic lymphocytes was found in the STZ-treated group. Furthermore, mice immunized with ovalbumin (OVA) showed a more intense antigen-specific paw edema response in the STZ-treated group, while production of anti-OVA IgG1 antibodies was similar in both groups. Thereby, important changes in immune cell parameters in vivo and in vitro were found at an early stage of T1D in the STZ-treated group, whereas alterations in the ALX-treated group were mostly found in the chronic phase of T1D, including increased mortality rates. These findings suggest that the effects of ALX and STZ influenced, at different times, lymphoid organs and their cell populations.