Microcirculatory Function during Endotoxemia—A Functional Citrulline-Arginine-NO Pathway and NOS3 Complex Is Essential to Maintain the Microcirculation

Competition for the amino acid arginine by endothelial nitric-oxide synthase (NOS3) and (pro-)inflammatory NO-synthase (NOS2) during endotoxemia appears essential in the derangement of the microcirculatory flow. This study investigated the role of NOS2 and NOS3 combined with/without citrulline supplementation on the NO-production and microcirculation during endotoxemia. Wildtype (C57BL6/N background; control; n = 36), Nos2-deficient, (n = 40), Nos3-deficient (n = 39) and Nos2/Nos3-deficient mice (n = 42) received a continuous intravenous LPS infusion alone (200 μg total, 18 h) or combined with L-citrulline (37.5 mg, last 6 h). The intestinal microcirculatory flow was measured by side-stream dark field (SDF)-imaging. The jejunal intracellular NO production was quantified by in vivo NO-spin trapping combined with electron spin-resonance (ESR) spectrometry. Amino-acid concentrations were measured by high-performance liquid chromatography (HPLC). LPS infusion decreased plasma arginine concentration in control and Nos3−/−compared to Nos2−/−mice. Jejunal NO production and the microcirculation were significantly decreased in control and Nos2−/−mice after LPS infusion. No beneficial effects of L-citrulline supplementation on microcirculatory flow were found in Nos3−/−or Nos2−/−/Nos3−/−mice. This study confirms that L-citrulline supplementation enhances de novo arginine synthesis and NO production in mice during endotoxemia with a functional NOS3-enzyme (control and Nos2−/−mice), as this beneficial effect was absent in Nos3−/−or Nos2−/−/Nos3−/−mice.

An exploratory study of the relationship between systemic microcirculatory function and small solute transport in incident peritoneal dialysis patients

Background: The peritoneal capillary endothelium is widely considered to be the most influential structure in dictating the rate of small solute transport (SST) during peritoneal dialysis (PD). PD patients are at significant risk of systemic microcirculatory dysfunction. The relationship between peritoneal and systemic microcirculations in patients new to PD has not been well studied. We hypothesised that for patients on PD for less than 6 months, dysfunction in the systemic microcirculation would be reflected in the rate of SST. Methods: We recruited 29 patients to a cross-sectional, observational study. Rate of SST was measured using a standard peritoneal equilibration test. Laser Doppler Flowmetry was used to measure response to physical and pharmacological challenge (post-occlusive hyperaemic response and iontophoretic application of vasodilators) in the cutaneous microcirculation. Sidestream Darkfield imaging was used to assess sublingual microvascular density, flow and endothelial barrier properties. Results: We found no moderate or strong correlations between any of the measures of systemic microcirculatory function and rate of SST or albumin clearance. There was however a significant correlation between dialysate interleukin-6 concentrations and both SST ( rs = 0.758 p ≤ 0.0001) and albumin clearance ( rs = 0.53, p = 0.01). Conclusions: In this study, systemic microvascular dysfunction did not significantly influence the rate of SST even early in patients PD careers. In conclusion, this study demonstrates that intraperitoneal factors particularly inflammation have a far greater impact on rate of SST than systemic factors.

The Role of Cutaneous Microcirculatory Responses in Tissue Injury, Inflammation and Repair at the Foot in Diabetes

Diabetic foot syndrome is one of the most costly complications of diabetes. Damage to the soft tissue structure is one of the primary causes of diabetic foot ulcers and most of the current literature focuses on factors such as neuropathy and excessive load. Although the role of blood supply has been reported in the context of macro-circulation, soft tissue damage and its healing in the context of skin microcirculation have not been adequately investigated. Previous research suggested that certain microcirculatory responses protect the skin and their impairment may contribute to increased risk for occlusive and ischemic injuries to the foot. The purpose of this narrative review was to explore and establish the possible link between impairment in skin perfusion and the chain of events that leads to ulceration, considering the interaction with other more established ulceration factors. This review highlights some of the key skin microcirculatory functions in response to various stimuli. The microcirculatory responses observed in the form of altered skin blood flow are divided into three categories based on the type of stimuli including occlusion, pressure and temperature. Studies on the three categories were reviewed including: the microcirculatory response to occlusive ischemia or Post-Occlusive Reactive Hyperaemia (PORH); the microcirculatory response to locally applied pressure such as Pressure-Induced Vasodilation (PIV); and the interplay between microcirculation and skin temperature and the microcirculatory responses to thermal stimuli such as reduced/increased blood flow due to cooling/heating. This review highlights how microcirculatory responses protect the skin and the plantar soft tissues and their plausible dysfunction in people with diabetes. Whilst discussing the link between impairment in skin perfusion as a result of altered microcirculatory response, the review describes the chain of events that leads to ulceration. A thorough understanding of the microcirculatory function and its impaired reactive mechanisms is provided, which allows an understanding of the interaction between functional disturbances of microcirculation and other more established factors for foot ulceration.

Protective Effect of Dachengqi Decoction on Pancreatic Microcirculatory in Severe Acute Pancreatitis via Down-regulating HMGB-TLR-4-IL-23-IL-17A Mediated Neutrophil Activation Though Targeting SIRT1

BackgroundDachengqi decoction (DCQD), one of classic prescription of Chinese herbal medicine has been widely used in clinic to treat severe acute pancreatitis (SAP). The damage of pancreatic microcirculation plays key pathogenesis of SAP. However, little is known about the molecular pharmacological activity of DCQD on pancreatic microcirculation in SAP. Therefore, the purpose of the study attempted to confirm the improvement of DCQD on pancreatic microcirculation is associated with suppressing neutrophil mediated immune-inflammatory response through promoting the inactivation of HMGB1-TLR-4-IL-23-IL-17A axis via targeting the SIRT1 signal pathway in SAP.Material and MethodsSodium taurodeoxycholate and cerulein were used to establish model of SAP in vitro and vivo, respectively. The pancreatic pathological morphology, wet weight ratio, myeloperoxidase (MPO) activity, cell viability and microcirculatory function of the pancreas, as well as serum lipase and amylase expressions were evaluated. The expression levels of SIRT1, acety-HMGB1, TLR-4, HMGB1, IL-23, IL-17A, neutrophil chemokines (KC, LIX, and MIP-2), and inflammation-related factors (IL-6, IL-1β, and TNF-α), the translocation of HMGB1 and the interaction of SIRT-HMGB1 in the pancreas and serum were determined by ELISA real-time PCR, western blotting and immunoprecipitation.ResultsIn-vivo studies showed DCQD or neutralizing antibody (anti-23p19 or anti-IL-17A) could significantly decrease the activity of lipase, amylase, down-regulate the expression of CD68, MPO, wet/weight, IL-1β, IL-6, TNF-α,neutrophil chemokines (KC, LIX, MIP-2 ), alleviate pathological injury, and improve the microcirculatory function of the pancreas in rats with SAP. Moreover, DCQD remarkably augmented SIRT1 expression, promoted SIRT1 and HMGB1 combination, reduced HMGB1 translocation from nuclear to cytoplasm, and alleviated the expression of acetyl-HMGB1, HMGB1, IL-17A, TLR-4 and IL-23 in vitro and vivo with SAP. However, the intervention with EX527 (SIRT1 inhibitor) or r-HMGB1 (recombinant HMGB1) could obliviously reverse the above-mentioned influence of DCQD in SAP. In vitro, we confirmed that DCQD could decrease the acetylation, migration and release of HMGB1, and improve the decline of cell viability, SIRT1, SIRI-HMGB1 combination induced by cerulein with promoting macrophage to release IL-23 through HMGB1/TLR-4. ConclusionDCQD treatment improves SAP-induced pancreatic microcirculatory dysfunction by inhibiting neutrophil-mediated inflammation through the inactivation of HMGB1-TLR-4-IL-23-IL-17A signaling via Targeting SIRT1.Trial registration: No. 365, 2020.

Comprehensive assessment of peripheral innervation and microcirculatory function in local cold trauma

Актуальность криопоражений обусловлена большим числом пострадавших, сложностью лечения, длительной утратой трудоспособности, тяжелыми последствиями и, как следствие, высоким уровнем инвалидизации. Цель исследования -- оценка изменений микрокровотока и периферической иннервации при местной холодовой травме и формирование прогностической модели уровня повреждения конечности. Методика. Под наблюдением было 35 больных с местной холодовой травмой нижних конечностей III-IV степени. Использован неинвазивный метод лазерной доплеровской флуометрии с помощью аппарата ЛАКК-02, а также метод накожной электронейромиографии с помощью аппарата Нейро-ВМП, компании Нейрософт. Результаты. Несмотря на гипотетически функциональную связь между микрокровотоком кожи и уровнем отморожения пораженной конечности, статистически значимых результатов получено не было (p > 0,05), что свидетельствует о более сложном генезе патологических изменений в пораженной конечности. Между тем, у пострадавших с местной криотравмой отмечены выраженные изменения периферической иннервации. Нейропатия прогрессирует с увеличением уровня повреждения. Заключение. У пациентов с местной холодовой травмой отмечается снижение биоэлектрической активности мышц в области пораженной конечности. Cryotrauma is relevant due to a large number of patients, the complexity of treatment, the likelihood of severe complications, and long-term disability. The aim was to assess oscillations in microcirculation and peripheral innervation during regional cold injury, and to form a prognostic model according to the severity of limb injury. Methods. Studies were carried out in 35 patients with III-IV degree local cold injury of a leg. Non-invasive laser Doppler flowmetry was performed with a LAKK-02 device, and peripheral innervation was evaluated by cutaneous electroneuromyography with a Neurosoft Neuro-VMP device. The patients were divided into 3 groups depending on the injury. Results. Despite the hypothetical, functional relationship between skin microcirculatory blood flow and the degree of frostbite of the affected tissue, no statistically significant association was detected (p > 0.05), which indicates a more complex genesis of the cold-induced pathology. However, there were pronounced changes in neural activity in this tissue. Neuropathy increased with increasing injury. Conclusions. In patients with local cold trauma there is a decrease in the bioelectric activity of the muscles in the damaged tissue.

Common Microcirculatory Framework for Monitoring Integrated Microcirculation

Wide variation in magnitudes, units, and ranges of the microcirculatory variables brings hindrance in describing and evaluating the integrated microcirculatory function of tissues. We designed to establish common microcirculatory framework that contains microhemodynamic and microcirculatory oxygen parameters. To integrate microcirculatory information, demo microcirculatory permutations were generated by a computer algorithm based on microcirculatory characteristics. Four dimensionless methods (Z-score, Min-max, L2, and median scaling) were applied to transform microcirculatory data set into the dimensionless form. Three-dimensional (3-D) common microcirculatory framework was constructed and visualized by using Python and Apache ECharts. The performance of the four dimensionless methods in the pre-processing of multiple microcirculatory variables and the establishment of the common microcirculatory framework were compared. Microhemodynamic and microcirculatory oxygen parameters were embedded in the common microcirculatory framework. After processing by Min-max normalization, the transformed multiple microcirculatory values remained positive with fixed range mapping within [0, 1] and maintained the identity property of microcirculation both of microhemodynamic and microcirculatory oxygen variables in the common microcirculatory framework. Conclusively, Min-max normalization displays preferable integration efficiency, compatibility, and adaptability in the establishment of the 3-D visualized multiparametric common microcirculatory framework.

Resveratrol Suppresses Severe Acute Pancreatitis-Induced Microcirculation Disturbance through Targeting SIRT1-FOXO1 Axis

Background. Resveratrol (RSV), one of the SIRT1 agonists, has the ability of alleviating severe acute pancreatitis (SAP); however, the concrete protective mechanism remains unknown. It is noteworthy that microcirculation disturbance plays a vital role in SAP, and the SIRT1/FOX1 axis can regulate microcirculation. Therefore, this study is aimed at ascertaining what is the underlying mechanism of the protective effect of RSV on SAP, and whether it is associated with alleviating microcirculation disturbance by regulating the SIRT1/FOX1 axis. Method. The model of SAP was induced by retrograde injection of sodium taurodeoxycholate into the bile duct of the rats. The pancreatic wet/dry weight, ET/NO, and TXB2/6-keto-PGF1α ratios; microcirculatory function; and SIRT1 activity were examined. ELISA was used to examine the serum level of lipase, amylase, hemorheology, ET, NO, TXB2, and 6-keto-PGF1α and the content of SIRT1, VEGF, Ang I, and Ang II in the pancreas. RT-PCR was used to examine the mRNA level of VEGF, Ang I, and Ang II. Western blotting was used to detect SIRT1, FOXO1, and acetyl-FOXO1. Immunoprecipitation was used to examine the interaction of SIRT1 and FOXO1. Results. Resveratrol can significantly decrease the expression of lipase, amylase, acetyl-FOXO1, VEGF, Ang II, ET, NO, TXB2, and 6-keto-PGF1α and the ratio of wet/dry weight, ET/NO, and TXB2/6-keto-PGF1α by improving microcirculatory dysfunction and blood viscosity in SAP. Moreover, resveratrol can also promote the interaction of SIRT1 and FOXO1 and increase SIRT1 activity and the expression of SIRT1 and Ang I. The SIRT1 inhibitor, Sirtinol (EX527), obliviously reversed the effects of RSV on SAP. Conclusion. Resveratrol can protect rats against SAP, and its protective mechanism is associated with suppressing microcirculation disturbance through activating SIRT1-FOXO1 axis.

Pulsatility Protects the Endothelial Function during Extracorporeal Membrane Oxygenation

Background Pulsatile flow has been proved to protect vital organ function and microcirculation during extracorporeal membrane oxygenation (ECMO). Studies revealed that pulsatile shear stress plays a vital role in the microcirculatory function and integrity. The objective of this study was to investigate how pulsatility affects wall shear stress and microcirculation during ECMO. Methods Using the i-Cor system, we compared the effects of pulstile or non-pulsatile flows in a canine ECMO model, with hemodynamic parameters and peak wall shear stress (PWSS) calculated. Serum concentrations of syndecan-1 and heparan sulfate were measured at different time points during ECMO. Pulstile shear stress experiments were also validated in endothelial cells exposed to different magnitude of pulsatility, with cell viability, the expressions of syndecan-1 and endothelial-to-mesenchymal tranformation (EndMT) markers analyzed. Results The pulsatile flow generated more surplus hemodynamic energy and preserved higher PWSS during ECMO. Serum concentrations of syndecan-1 and heparan sulfate were both negatively correlated with PWSS, and significantly lower levels were observed in the pulsatile group. In addition, non-pulsatility triggered EndMT, with EndMT related genes up-regulated, and endothelial cells exposed to low pulsatility had the lowest possibility of EndMT. Conclusion The maintenance of the PWSS by pulsatility during ECMO contributes to the beneficial effects on glycocalyx integrity and microcirculatory function. Moreover, pulsatility prevents EndMT in endothelial cells, and low pulsatility exhibits the best protective effects. The augmentation of pulsatility may be a future direction to improve the clinical outcome in ECMO.