Human-relevant near-organ neuromodulation of the immune system via the splenic nerve.

Neuromodulation of immune function by stimulating the autonomic connections to the spleen has been demonstrated in rodent models. Consequently, neuroimmune modulation has been proposed as a new therapeutic strategy for the treatment of inflammatory conditions. However, demonstration of the translation of these immunomodulatory mechanisms in anatomically and physiologically relevant models is still lacking. Additionally, translational models are required to identify stimulation parameters that can be transferred to clinical applications of bioelectronic medicines. Here, we performed neuroanatomical and functional comparison of the mouse, rat, pig, and human splenic nerve using in vivo and ex vivo preparations. The pig was identified as a more suitable model of the human splenic innervation. Using functional electrophysiology, we developed a clinically relevant marker of splenic nerve engagement through stimulation-dependent reversible reduction in local blood flow. Translation of immunomodulatory mechanisms were then assessed using pig splenocytes and two models of acute inflammation in anesthetized pigs. The pig splenic nerve was shown to locally release noradrenaline upon stimulation, which was able to modulate cytokine production by pig splenocytes. Splenic nerve stimulation was found to promote cardiovascular protection as well as cytokine modulation in a high- and a low-dose lipopolysaccharide model, respectively. Importantly, splenic nerve-induced cytokine modulation was reproduced by stimulating the efferent trunk of the cervical vagus nerve. This work demonstrates that immune responses can be modulated by stimulation of spleen-targeted autonomic nerves in translational species and identifies splenic nerve stimulation parameters and biomarkers that are directly applicable to humans due to anatomical and electrophysiological similarities.

Agonistic autoantibodies against ß2-adrenergic receptor influence retinal microcirculation in glaucoma suspects and patients.

PURPOSE: Agonistic ß2-adrenergic receptor autoantibodies (ß2-agAAb) have been observed in sera of patients with ocular hypertension and open-angle glaucoma (OAG). They target the ß2-receptors on trabecular meshwork, ciliary body and pericytes (Junemann et al. 2018; Hohberger et al. 2019). In addition to their influence on the intraocular pressure, an association to retinal microcirculation is discussed. This study aimed to investigate foveal avascular zone (FAZ) characteristics by en face OCT angiography (OCT-A) in glaucoma suspects and its relationship to ß2-agAAb status in patients with OAG. MATERIAL AND METHODS: Thirty-four patients (28 OAG, 6 glaucoma suspects) underwent standardized, clinical examination including sensory testing as white-on-white perimetry (Octopus G1, mean defect, MD) and structural measures as retinal nerve fibre layer (RNFL) thickness, neuroretinal rim width (BMO-MRW), retinal ganglion cell layer (RGCL) thickness, and inner nuclear layer (INL) thickness with high-resolution OCT. FAZ characteristics were measured by OCT-A scans of superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). FAZ-R was calculated (area FAZ (SVP)/area FAZ (ICP)). Using cardiomyocyte bioassays we analysed serum samples for the presence of ß2-agAAb. RESULTS: (I) Total mean FAZ area [mm2]: 0.34±0.16 (SVP), 0.24±0.12 (ICP), and 0.49±0.24 (DCP); mean FAZ-R 1.58±0.94. No correlation was seen for FAZ-R with MD, RNFL, BMO-MRW, RGCL thickness and INL thickness (p>0.05). (II) ß2-agAAb have been observed in 91% patients and showed no correlation with MD, RNFL, BMO-MRW, RGCL thickness and INL thickness (p>0.05). (III) FAZ-R correlated significantly with the ß2-agAAb-induced increase of the beat rate of cardiomyocyte (p = 0.028). CONCLUSION: FAZ characteristics did not correlate with any glaucoma associated functional and morphometric follow-up parameter in the present cohort. However, level of ß2-agAAb showed a significantly correlation with FAZ-ratio. We conclude that ß2-agAAb might be a novel biomarker in glaucoma pathogenesis showing association to FAZ-ratio with OCT-A.

Microcirculation-guided protection strategy in hemodynamic therapy.

Microcirculatory shock is a condition defined by the presence of tissue hypoperfusion despite the normalization of systemic and regional blood flow. Currently, more evidence shows that intrinsic septic shock is microcirculatory shock, which results in septic shock that is difficult to resuscitate. At present, treatments are aimed at recovering macro-circulation functions and include fluid resuscitation, vasoactive drugs, positive inotropic drugs, de-obstruction, and even mechanical assistance to improve oxygen delivery. However, the application of these treatments to more accurately improve microcirculation or avoid further microcirculatory damage is more important in clinics. In this article, we discuss the need for microcirculation protection and microcirculation-guided protection strategies in hemodynamic therapies.

Microrheology, microcirculation and structural compensatory mechanisms of a chronic kidney disease rat model. A preliminary study.

BACKGROUND: Chronic kidney disease (CKD) models are known to study pathophysiology and various treatment methods. Renal dysfunction could influence erythrocytes through several pathways. However, hemorheological and microcirculatory relation of CKD models are not completely studied yet. OBJECTIVE: To evaluate erythrocyte micro-rheology, microcirculatory and structural compensatory mechanisms in a rat model of CKD. METHODS: Female Sprague-Dawley rats were subjected to nephrectomy group (NG, n = 6) or sham-operated group (SG, n = 6). NG rats were subjected to 5/6 nephrectomy in two stages. In SG no intervention was made on kidneys. Hemorheological and hematological measurements were carried out after each stage, and 5 weeks after the last operation. Histological and microcirculatory studies were done on the remaining kidney and compared with sham rats. RESULTS: Serum creatinine increased in NG (p = 0.008), accompanied with decrease of red blood cell count (p = 0.028) and hemoglobin (p = 0.015). Erythrocyte aggregation parameters slightly increased in NG, while the elongation index didn't show significant changes. Microcirculation was intact in the remnant kidney of NG. However, in comparison with SG, the diameter of glomeruli increased significantly (p < 0.01). CONCLUSIONS: Erythrocyte mass was influenced more than micro-rheological properties in this model. The main compensation mechanism was rather structural than at microcirculatory level.

Endocan as a marker of microvascular inflammation in kidney transplant recipients.

Endocan is a water-soluble proteoglycan exclusively secreted by vascular endothelium. Endocan levels may be elevated in kidney transplant recipients experiencing antibody-mediated rejection (ABMR), which is characterized by vascular inflammation in transplanted kidney. We evaluated the clinical relevance of endocan as markers of microvascular inflammation in patients who underwent kidney transplantation. Plasma and urinary endocan levels were measured in 203 kidney transplant recipients and were compared across different etiologies of allograft dysfunction and various pathologic scores. Both plasma and urinary endocan levels were significantly higher in patients with acute ABMR than those in patients with normal pathology, acute tubular necrosis (ATN), acute pyelonephritis, BK virus associated nephropathy (BKVN), and T-cell mediated rejection (TCMR). Patients with chronic active ABMR also exhibited significantly higher plasma and urinary endocan levels than patients with long-term graft survival. Scores of glomerulitis and peritubular capillaritis, which are typical features of microvascular inflammation, were significantly elevated in patients with higher plasma and/or urinary endocan levels. Furthermore, plasma and urinary endocan levels could effectively discriminate ABMR from ATN, BKVN, and TCMR. Finally, patients exhibiting high urinary and plasma endocan levels in acute ABMR group showed significantly worse renal survival. Altogether, plasma and urinary endocan levels may serve as potential markers of microvascular inflammation in kidney transplant recipients.

Group II innate lymphoid cells and microvascular dysfunction from pulmonary titanium dioxide nanoparticle exposure.

BACKGROUND: The cardiovascular effects of pulmonary exposure to engineered nanomaterials (ENM) are poorly understood, and the reproductive consequences are even less understood. Inflammation remains the most frequently explored mechanism of ENM toxicity. However, the key mediators and steps between lung exposure and uterine health remain to be fully defined. The purpose of this study was to determine the uterine inflammatory and vascular effects of pulmonary exposure to titanium dioxide nanoparticles (nano-TiO2). We hypothesized that pulmonary nano-TiO2 exposure initiates a Th2 inflammatory response mediated by Group II innate lymphoid cells (ILC2), which may be associated with an impairment in uterine microvascular reactivity. METHODS: Female, virgin, Sprague-Dawley rats (8-12 weeks) were exposed to 100 µg of nano-TiO2 via intratracheal instillation 24 h prior to microvascular assessments. Serial blood samples were obtained at 0, 1, 2 and 4 h post-exposure for multiplex cytokine analysis. ILC2 numbers in the lungs were determined. ILC2s were isolated and phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB) levels were measured. Pressure myography was used to assess vascular reactivity of isolated radial arterioles. RESULTS: Pulmonary nano-TiO2 exposure was associated with an increase in IL-1ß, 4, 5 and 13 and TNF- α 4 h post-exposure, indicative of an innate Th2 inflammatory response. ILC2 numbers were significantly increased in lungs from exposed animals (1.66 ± 0.19%) compared to controls (0.19 ± 0.22%). Phosphorylation of the transactivation domain (Ser-468) of NF-κB in isolated ILC2 and IL-33 in lung epithelial cells were significantly increased (126.8 ± 4.3% and 137 ± 11% of controls respectively) by nano-TiO2 exposure. Lastly, radial endothelium-dependent arteriolar reactivity was significantly impaired (27 ± 12%), while endothelium-independent dilation (7 ± 14%) and α-adrenergic sensitivity (8 ± 2%) were not altered compared to control levels. Treatment with an anti- IL-33 antibody (1 mg/kg) 30 min prior to nano-TiO2 exposure resulted in a significant improvement in endothelium-dependent dilation and a decreased level of IL-33 in both plasma and bronchoalveolar lavage fluid. CONCLUSIONS: These results provide evidence that the uterine microvascular dysfunction that follows pulmonary ENM exposure may be initiated via activation of lung-resident ILC2 and subsequent systemic Th2-dependent inflammation.

Brain Endothelium: The "Innate Immunity Response Hypothesis" in Cerebral Malaria Pathogenesis.

Cerebral malaria (CM) is a life-threatening neurological syndrome caused by Plasmodium falciparum infection afflicting mainly children in Africa. Current pathogenesis models implicate parasite and host-derived factors in impairing brain vascular endothelium (BVE) integrity. Sequestration of Plasmodium-infected red blood cells (iRBCs) in brain microvessels is a hallmark of CM pathology. However, the precise mechanisms driving loss of blood-brain barrier (BBB) function with consequent brain injury are still unsettled and it is plausible that distinct pathophysiology trajectories are involved. Studies in humans and in the mouse model of CM indicate that inflammatory reactions intertwined with microcirculatory and coagulation disturbances induce alterations in vascular permeability and impair BBB integrity. Yet, the role of BVE as initiator of immune responses against parasite molecules and iRBCs is largely unexplored. Brain endothelial cells express pattern recognition receptors (PRR) and are privileged sensors of blood-borne infections. Here, we focus on the hypothesis that innate responses initiated by BVE and subsequent interactions with immune cells are critical to trigger local effector immune functions and induce BBB damage. Uncovering mechanisms of BVE involvement in sensing Plasmodium infection, recruiting of immune cells and directing immune effector functions could reveal pharmacological targets to promote BBB protection with potential applications in CM clinical management.

Immune response to systemic inflammation in the intestinal microcirculation.

Systemic inflammation is characterized by acute or chronic dysregulation of the host immune response. The intestine plays an important role in systemic inflammation. Disturbances in the intestinal microcirculation due to infiltration of immune cells during systemic inflammation can increase bacterial translocation from the gut to the circulation and aggravate the pathological condition. Therefore, the intestinal microcirculation is relevant with respect to two aspects - as pathophysiological trigger and therapeutic target in systemic inflammation. Experimental intravital microscopy represents a unique method to study the immune response in organs and tissues in vivo. Novel non-invasive imaging technologies facilitate the examination of the human microcirculation. Future developments are needed to miniaturize the imaging technologies and automate the time-consuming analyses of the in vivo data in order to make the intestinal microcirculation accessible for routine diagnostics and therapeutic monitoring.

[Impacts of mild moxibustion on immune indices and nailfold microcirculation in the subhealthy group].

OBJECTIVE: To compare the difference in the clinical therapeutic effects of the regulation of subhealthy condition between the mild moxibustion on alternate days and Chinese herbal medicine. METHODS: Seventy-two participants of subhealthy condition were assigned into a mild moxibustion group (36 cases) and a medication group (36 cases) according to random number table. In the mild moxibustion group, the intervention of mild moxibustion with moxa stick was applied to Guanyuan (CV 4), Zusanli (ST 36) and Sanyinjiao (SP 6), once every other day. In the medication group, yupingfeng granules were prescribed for oral administration, three times a day. The treatment was continued for 2 months. Before and after treatment, the levels of IgA, IgM and IgG, SOD (superoxide dismutase), the total score of fatigue scale 14 (FS-14) and the score of nailfold microcirculation were observed separately. RESULTS: Compared with the results before treatment, the immune indices, the total score of FS-14 and the scores of nailfold microcirculation were all improved after treatment in the two groups, indicating the significant differences (P<0.05, P<0.01). In comparison between the two groups after treatment, the levels of immune globulin, e.g. IgM, IgG and SOD in the mild moxibustion group were higher in tendency than those in the medication group, but without significant differences (all P>0.05). The total score of FS-14 after treatment in the mild moxibustion group was lower than that in the medication group (P<0.05). After treatment, in the mild moxibustion group, for the nailfold microcirculation, the flow state score, the periloop score and the total score were all reduced more apparently as compared with those in the medication group (P<0.01, P<0.05). CONCLUSIONS: Mild moxibustion with moxa stick on alternate days apparently relieves fatigue state, immune dysfunction and microcirculatory impairment in the subhealthy group. The results are apparently superior to the treatment with yupingfeng granules.

Galectin-3: A Positive Regulator of Leukocyte Recruitment in the Inflamed Microcirculation.

In vivo and ex vivo imaging were used to investigate the function of galectin-3 (Gal-3) during the process of leukocyte recruitment to the inflamed microcirculation. The cremasteric microcirculation of wild-type (C57BL/6), Gal-3-/-, and CX3CR1gfp/+ mice were assessed by intravital microscopy after PBS, IL-1ß, TNF-α, or recombinant Gal-3 treatment. These cellular responses were investigated further using flow-chamber assays, confocal microscopy, flow cytometry, PCR analysis, and proteome array. We show that mechanisms mediating leukocyte slow rolling and emigration are impaired in Gal-3-/- mice, which could be because of impaired expression of cell adhesion molecules and an altered cell surface glycoproteome. Local (intrascrotal) administration of recombinant Gal-3 to wild-type mice resulted in a dose-dependent reduction in rolling velocity associated with increased numbers of adherent and emigrated leukocytes, ∼50% of which were Ly6G+ neutrophils. Intrascrotal administration of Gal-3 to CX3CR1gfp/+ mice confirmed that approximately equal numbers of monocytes are also recruited in response to this lectin. Exogenous Gal-3 treatment was accompanied by increased proinflammatory cytokines and chemokines within the local tissue. In conclusion, this study unveils novel biology for both exogenous and endogenous Gal-3 in promoting leukocyte recruitment during acute inflammation.

Role of T-Cell Dysfunction, Inflammation, and Coagulation in Microvascular Disease in HIV.

BACKGROUND: Compared to uninfected adults, HIV-infected adults on antiretroviral therapy are at increased risk of cardiovascular disease. Given the increase in T-cell dysfunction, inflammation, and coagulation in HIV infection, microvascular dysfunction is thought to contribute to this excess cardiovascular risk. However, the relationships between these variables remain undefined. METHODS AND RESULTS: This was a cross-sectional study of 358 HIV-infected adults from the SCOPE cohort. Macrovascular endothelial function was assessed using flow-mediated dilation of the brachial artery and microvascular function by reactive hyperemia. T-cell phenotype was determined by flow cytometry. Plasma markers of inflammation (tumor necrosis factor-α, interleukin-6, high-sensitivity C-reactive protein, sCD14) and coagulation (fibrinogen, D-dimer) were also measured. In all HIV+ subjects, markers of inflammation (tumor necrosis factor-α, high-sensitivity C-reactive protein), coagulation (D-dimer) and T-cell activation (CD8+PD1+, CD4+interferon+cytomegalovirus-specific) were associated with worse reactive hyperemia after adjusting for traditional cardiovascular risk factors and co-infections. In treated and suppressed subjects, tumor necrosis factor-α and CD8+PD1+ cells remained associated with worse reactive hyperemia after adjustment. Compared to the untreated subjects, CD8+PD1+ cells were increased in the virally suppressed group. Reactive hyperemia was predictive of flow-mediated dilation. CONCLUSIONS: CD8+PD1+ cells and tumor necrosis factor-α were associated with microvascular dysfunction in all HIV+ subjects and the treated and suppressed group. Additionally, D-dimer, high-sensitivity C-reactive protein, sCD-14, and interleukin-6 were associated with microvascular dysfunction in all HIV+ subjects. Although T-cell dysfunction, inflammation, and microvascular dysfunction are thought to play a role in cardiovascular disease in HIV, this study is the first to look at which T-cell and inflammatory markers are associated with microvascular dysfunction in HIV-infected individuals.

Experimental Cannabinoid 2 Receptor Inhibition in CNS Injury-Induced Immunodeficiency Syndrome.

OBJECTIVE: Severe CNS injury, such as stroke, traumatic brain injury, or spinal cord injury, is known to increase susceptibility to infections. The increased susceptibility to infection is due to an impaired immune response and is referred to as CIDS. The CB2 receptor on immune cells presents a potential therapeutic target in CIDS as activation of this receptor has been shown to be involved in immunosuppression. The main purpose of this study was to determine the impact of CB2 receptor inhibition on leukocyte activation within the microcirculation following endotoxin challenge in an experimental stroke model. METHODS: Five experimental groups (male C57BL/6 mice, age: 6-8 weeks) were subjected to the following treatments: control; endotoxemia (LPS 5 mg/kg, i.v.); transient cerebral hypoxia-ischemia (HI) + endotoxemia; HI + endotoxemia + CB2 receptor antagonist (AM630 2.5 mg/kg, i.v.). HI was induced by unilateral carotid artery occlusion, followed by 50 minute exposure to a low oxygen atmosphere (8% O2 ). The CB2 receptor antagonist was given 15 min prior to LPS administration. Intravital microscopy (IVM) was carried out 2h after LPS administration. Brains were extracted and stained with tetrazolium chloride (TTC) to measure infarct volume. RESULTS: Compared to endotoxemic animals without CNS injury, mice subjected to HI displayed reduced leukocyte activation in intestinal submucosal venules indicative of CIDS. Administration of the CB2 receptor antagonist in animals with CIDS challenged with endotoxin restored peripheral leukocyte recruitment without a detrimental impact on infarct size. CONCLUSION: We conclude that the ECS is involved in the impaired immune response following CNS injury. Future studies should further explore the CB2 receptor pathway to develop novel therapies for CIDS.

Intravital microscopy - A novel tool in characterizing congestive heart failure in experimental autoimmune myocarditis.

AIMS: Experimental autoimmune myocarditis (EAM) is a widely used murine model, in which cellular myocardial infiltration resembles human viral myocarditis. Although myocarditis can be readily assessed on histology, heart failure has not been fully characterized, as there are limitations in available markers and difficulties in hemodynamic measurements, especially on small rodents. We investigated whether intravital microscopy of the microcirculation can be used to characterize heart failure in EAM. METHODS: BALB/c mice (n = 10 versus n = 5 controls) were immunized with alpha myosin heavy chain peptide and myocarditis was confirmed on hematoxylin-eosin (HE) histology on day 21. Echocardiography assessment included ejection fraction (EF), fractional shortening (FS), mitral valve doppler, left-ventricular end-diastolic diameter (LVEDd) and diastolic intra-ventricular septum thickness (IVSd). Microcirculatory analysis was performed using a sidestream dark field (SDF) microcirculation camera. The proportion of perfused vessels (PPV) and perfused vessel density (PVD) were recorded on the intestinal mucosa of the anaesthesized mice. RESULTS: Immunized mice developed EAM with typical cellular infiltration (p < 0.003), left-ventricular hypertrophy (IVSd, p = 0.027) and diastolic dysfunction (E/A, p = 0.028) without significant EF reduction (p = 0.845) or LV dilation (p = 0.854). SDF recording consisted mainly of venules, as capillaries were too small. PPV and PVD were significantly increased in EAM mice (p 0.001 and 0.01 respectively) and correlated significantly with the histological myocarditis severity score (r = 0.557, p = 0.03 and r = 0.57, p = 0.025 respectively), whereas PPV but not PVD correlated with IVSd (r = 0.588, p = 0.02) and E/A ratio (r = 0.703, p = 0.003). CONCLUSIONS: Intravital microscopy can be used to characterize post-capillary intestinal perfusion of EAM mice. Thus we show a congestion of intestinal venules in EAM which correlates to the severity of myocarditis.

Conjunctival microvascular hemodynamics following vaso-occlusive crisis in sickle cell disease.

Painful vaso-occlusive crisis (VOC) is the clinical hallmark of sickle cell disease (SCD). Microcirculatory hemodynamic changes following painful VOC may be indicative of future development of VOC events in subjects with SCD. The purpose of the present study was to determine alterations in conjunctival microvascular hemodynamics during non-crisis state in SCD subjects with a history of VOC. Conjunctival microcirculation imaging was performed to measure conjunctival diameter (D) and axial blood velocity (V) in 10 control and 30 SCD subjects. SCD subjects were categorized into two groups based on their history of VOC within a 2-year period before imaging (with or without VOC-H) and also based on whether there was progression in the rate of VOCs during a 2-year period following imaging as compared to before imaging (with or without VOC-P). Conjunctival V was significantly higher in SCD subjects with VOC-H than in both control subjects and SCD subjects without VOC-H (P≤0.03). Conjunctival V was also significantly higher in SCD subjects with VOC-P compared with control subjects and SCD subjects without VOC-P (P≤0.03). Assessment of the conjunctival microcirculation may be useful for understanding hemodynamic changes that lead to VOC events in SCD subjects.

Elevated plasma pentraxin 3 levels are associated with development and progression of diabetic retinopathy in Korean patients with type 2 diabetes mellitus.

PURPOSE: To evaluate the association between elevated levels of plasma pentraxin 3 (PTX3) and the development and/or progression of diabetic retinopathy (DR). METHODS: In this case-control study, 92 diabetic patients with DR (group 3), 30 diabetic patients without DR (group 2), and 41 normal subjects (group 1) were enrolled. Log-transformed values of plasma PTX3 and high-sensitivity C-reactive protein (hsCRP) concentrations were measured and used in our analysis. For subgroup analysis, group 3 was divided into four subgroups: mild, moderate, severe nonproliferative, and proliferative DR. RESULTS: In our 163 participants, average plasma PTX3 levels were 916.1 ± 532.2, 1093.7 ± 1034.2, and 1817.9 ± 1776.9 pg/mL for groups 1, 2, and 3, respectively. The duration of diabetic mellitus (DM), glycated hemoglobin (HbA1c), log hsCRP, and log PTX3 were significantly different between the three groups (P = 0.008, P < 0.001, P = 0.046, and P < 0.001, respectively). In subgroup analysis, plasma log PTX3 levels increased in correlation with the severity of DR (R = 0.372, P < 0.001). Multivariate logistic analysis showed that the correlation between DR development and duration of DM and log PTX3 values was significant (P = 0.014 and P = 0.025, respectively), whereas correlation with log hsCRP values was not significant in univariate analysis (P = 0.129). The receiver operating characteristic curves of DR development were plotted using log PTX3 and log hsCRP values, and the area under the curves was found to be 0.721 (P = 0.001) and 0.614 (P = 0.087), respectively. CONCLUSIONS: Plasma PTX3 is positively associated with DR development and progression, and may be a more accurate predictor of DR development than hsCRP.

Augmenter of liver regeneration attenuates inflammatory response in the postischemic mouse liver in vivo.

BACKGROUND: Augmenter of Liver Regeneration (ALR), a protein synthesized in the liver is suggested to be protective against oxidative stress-induced cell death. Hepatic ischemia-reperfusion (I/R) injury is triggered by reactive oxygen species. Here, we tested the hypothesis that ALR attenuates hepatic I/R injury in vivo. METHODS: C57BL6 mice were subjected to warm hepatic ischemia for 90 min. Either recombinant ALR (100 µg/kg) or vehicle were administered to mice prior ischemia. During reperfusion, neutrophil and CD4+ T cell migration and sinusoidal perfusion were analyzed using intravital microscopy. Alanine aminotransferase-aspartate aminotransferase (plasma) and caspase-3 (tissue) activities were determined as markers of hepatocellular necrotic and apoptotic injury. RESULTS: Hepatic I/R led to dramatic enhancement of neutrophil and CD4+ T cell recruitment in hepatic microvessels, sinusoidal perfusion failure, and strong elevation of aspartate aminotransferase-alanine aminotransferase and caspase-3 activities. During early reperfusion (60 min), the pretreatment with ALR improved postischemic perfusion failure (P < 0.05) and attenuated liver enzyme activities. Recruitment of CD4+ T cells, but not of neutrophils was attenuated. After 240 min of reperfusion, the protective effect of ALR was stronger, since the liver enzyme activity, perfusion failure, and leukocyte influx were significantly attenuated. As shown by the measurement of caspase-3 activity, postischemic apoptosis was reduced in the ALR-treated group. CONCLUSIONS: Our in vivo data show that ALR has a therapeutic potential against postischemic liver injury. As a mechanism, we suggest a direct protective effect of ALR on apoptotic and necrotic death of hepatocytes and an attenuation of inflammatory cell influx into the postischemic tissue.

Experimental cannabinoid 2 receptor-mediated immune modulation in sepsis.

Sepsis is a complex condition that results from a dysregulated immune system in response to a systemic infection. Current treatments lack effectiveness in reducing the incidence and mortality associated with this disease. The endocannabinoid system offers great promise in managing sepsis pathogenesis due to its unique characteristics. The present study explored the effect of modulating the CB2 receptor pathway in an acute sepsis mouse model. Endotoxemia was induced by intravenous injection of lipopolysaccharide (LPS) in mice and intestinal microcirculation was assessed through intravital microscopy. We found that HU308 (CB2 receptor agonist) reduced the number of adherent leukocytes in submucosal venules but did not restore muscular and mucosal villi FCD in endotoxemic mice. AM630 (CB2 receptor antagonist) maintained the level of adherent leukocytes induced by LPS but further reduced muscular and mucosal villi FCD. URB597 (FAAH inhibitor) and JZL184 (MAGL inhibitor) both reduced the number of adherent leukocytes in submucosal venules but did not restore the mucosal villi FCD. Using various compounds we have shown different mechanisms of activating CB2 receptors to reduce leukocyte endothelial interactions in order to prevent further inflammatory damage during sepsis.

Obesity and coronary microvascular disease - implications for adipose tissue-mediated remote inflammatory response.

It is believed that obesity has detrimental effects on the coronary circulation. These include immediate changes in coronary arterial vasomotor responsiveness and the development of occlusive large coronary artery disease. Despite its critical role in regulating myocardial perfusion, the altered behavior of coronary resistance arteries, which gives rise to coronary microvascular disease (CMD) is poorly understood in obesity. A chronic, low-grade vascular inflammation has been long considered as one of the main underlying pathology behind CMD. The expanded adipose tissue and the infiltrating macrophages are the major sources of pro-inflammatory mediators that have been implicated in causing inadequate myocardial perfusion and, in a long term, development of heart failure in obese patients. Much less is known the mechanisms regulating the release of these cytokines into the circulation that enable them to exert their remote effects in the coronary microcirculation. This mini review aims to examine recent studies describing alterations in the vasomotor function of coronary resistance arteries and the role of adipose tissue-derived pro-inflammatory cytokines and adipokines in contributing to CMD in obesity. We provide examples of regulatory mechanisms by which adipokines are released from adipose tissue to exert their remote inflammatory effects on coronary microvessels. We identify some of the important challenges and opportunities going forward.

Cytomegalovirus-responsive γδ T cells: novel effector cells in antibody-mediated kidney allograft microcirculation lesions.

Human cytomegalovirus infection in transplant recipients has been associated with adverse renal allograft outcome and with a large γδ T-cell response, but whether both mechanisms are connected is unknown. We previously showed that most expanded circulating cytomegalovirus-responsive γδ T cells express the Fcγ-receptor CD16, suggesting that γδ T cells may participate in allograft lesions mediated by donor-specific antibodies through antibody-dependent cellular cytotoxicity. Here, we show that cytomegalovirus-specific CD16(pos) γδ T cells can perform antibody-dependent cellular cytotoxicity against stromal cells coated with donor-specific antibodies in vitro. In vivo, graft-infiltrating γδ T cells localized in close contact with endothelial cells only in patients who experienced cytomegalovirus infection and were more frequent within peritubular capillaries and glomeruli from antibody-mediated acute rejections than within those from T cell-mediated acute rejections. Finally, a persistently increased percentage of circulating cytomegalovirus-induced γδ T cells correlated inversely with the 1-year eGFR only in kidney recipients with donor-specific antibodies. Collectively, these data support the conclusion that cytomegalovirus-induced γδ T cells are involved in, and may serve as a clinical biomarker of, antibody-mediated lesions of kidney transplants. Moreover, these findings offer a new physiopathologic link between cytomegalovirus infection and allograft dysfunction in recipients with donor-specific antibodies.

Capillary dilation and rarefaction are correlated with intracapillary inflammation in antibody-mediated rejection.

Antibody-mediated rejection (ABMR) remains one of the major causes of graft loss after renal transplantation. It is dominated by endothelial damage in microcirculation. Clarifying the mechanism of microcirculating damage is obviously a key step to understand the pathogenesis of ABMR. Here we characterized capillary variation in ABMR and its possible mechanisms. Compared with T cell-mediated rejection and stable grafts, there was a significant dilation and rarefaction in peritubular capillaries (PTCs) of the ABMR group; Image-Pro Plus revealed a significantly larger intra-PTC area. Interestingly, the dilation of PTCs was strongly correlated with the intra-PTC cell counting. Moreover, peritubular capillary inflammation is correlated with in situ T-bet expression, and there was a good correlation between the intra-PTC expression of T-bet and the PTC diameter. HIF-1α up-regulation could be observed in ABMR but it was not necessary for capillary dilation. In general, ABMR is characterized with early capillary dilation and rarefaction; our data confirmed that the dilation is strongly correlated with intracapillary inflammation, which in turn is correlated with in situ T-bet expression. T-bet plays an important role in the development of microcirculating injury, and thus it is a potential target for the treatment of ABMR.