New Insights into the Immunobiology of Mononuclear Phagocytic Cells and Their Relevance to the Pathogenesis of Cardiovascular Diseases

A simplified herbal decoction attenuates myocardial infarction by regulating macrophage metabolic reprogramming and phenotypic differentiation via modulation of the HIF-1α/PDK1 axis

BACKGROUND

Myocardial infarction (MI) poses a global public health challenge, often associated with elevated mortality rates and a grim prognosis. A crucial aspect of the inflammatory injury and healing process post-MI involves the dynamic differentiation of macrophages. A promising strategy to alleviate myocardial damage after MI is by modulating the inflammatory response and orchestrating the shift from pro-inflammatory (M1) to anti-inflammatory (M2) macrophages, aiming to achieve a reduced M1/M2 ratio. Nuanxinkang (NXK), a simplified herbal decoction, has demonstrated noteworthy cardioprotective, inflammation-regulating, and myocardial energy metabolism-regulating properties.

METHODS

In this study, we constructed an MI model by ligating coronary arteries to investigate the efficacy of NXK in improving ventricular remodeling and cardiac function. Mice were administered NXK (1.65 g/kg/d) or an equivalent volume of regular saline via gavage for 28 consecutive days, commencing the day after surgery. Then, we conducted echocardiography to assess the cardiac function, Masson staining to illustrate the extent of myocardial fibrosis, TUNEL staining to reveal myocardial apoptosis, and flow cytometry to analyze the polarization of M1 and M2 macrophages in the hearts. Besides, a lipopolysaccharide (LPS)-induced pro-inflammatory macrophage (M1) polarization model was implemented in RAW264.7 cells to elucidate the underlying mechanism of NXK in regulating macrophage polarization. RAW264.7 cells were pre-treated with or without NXK-containing serum. Oxidative stress was detected by MitoSox staining, followed by Seahorse energy metabolism assay to evaluate alterations in mitochondrial metabolic patterns and ATP production. Both In vivo and in vitro, HIF-1α and PDK1 were detected by fluorescent quantitative PCR and Western blotting.

RESULTS

In vivo, MI mice exhibited a decline in cardiac function, adverse ventricular remodeling, and an increase in glycolysis, coupled with M1-dominant polarization mediated by the HIF-1α/PDK1 axis. Notably, robust responses were evident with high-dose NXK treatment (1.65 g/kg/day), leading to a significant enhancement in cardiac function, inhibition of cardiac remodeling, and partial suppression of macrophage glycolysis and the inflammatory phenotype in MI mice. This effect was achieved through the modulation of the HIF-1α/PDK1 axis. In vitro, elevated levels of mitochondrial ROS production and glycolysis were observed in LPS-induced macrophages. Conversely, treatment with NXK notably reduced the oxidative stress damage induced by LPS and enhanced oxidative phosphorylation (OXPHOS). Furthermore, NXK demonstrated the ability to modify the energy metabolism and inflammatory characteristics of macrophages by modulating the HIF-1α/PDK1 axis. The influence of NXK on this axis was partially counteracted by the HIF-1α agonist DMOG. And NXK downregulated PDK1 expression, curtailed glycolysis, and reversed LPS-induced M1 polarization in macrophages, similar to the PDK1 inhibitor DCA.

CONCLUSION

In conclusion, NXK protects against MI-induced cardiac remodeling by inducing metabolic reprogramming and phenotypic differentiation of macrophages, achieved through the modulation of the HIF-1α/PDK1 axis. This provides a novel and promising strategy for the treatment of MI.

Fenofibrate Induces a Resolving Profile in Heart Macrophage Subsets and Attenuates Acute Chagas Myocarditis

Chagas disease, caused by Trypanosoma cruzi, stands as the primary cause of dilated cardiomyopathy in the Americas. Macrophages play a crucial role in the heart's response to infection. Given their functional and phenotypic adaptability, manipulating specific macrophage subsets could be vital in aiding essential cardiovascular functions including tissue repair and defense against infection. PPARα are ligand-dependent transcription factors involved in lipid metabolism and inflammation regulation. However, the role of fenofibrate, a PPARα ligand, in the activation profile of cardiac macrophages as well as its effect on the early inflammatory and fibrotic response in the heart remains unexplored. The present study demonstrates that fenofibrate significantly reduces not only the serum activity of tissue damage biomarker enzymes (LDH and GOT) but also the circulating proportions of pro-inflammatory monocytes (CD11b+ LY6Chigh). Furthermore, both CD11b+ Ly6Clow F4/80high macrophages (MΦ) and recently differentiated CD11b+ Ly6Chigh F4/80high monocyte-derived macrophages (MdMΦ) shift toward a resolving phenotype (CD206high) in the hearts of fenofibrate-treated mice. This shift correlates with a reduction in fibrosis, inflammation, and restoration of ventricular function in the early stages of Chagas disease. These findings encourage the repositioning of fenofibrate as a potential ancillary immunotherapy adjunct to antiparasitic drugs, addressing inflammation to mitigate Chagas disease symptoms.

Immune dysfunction in patients with end stage kidney disease; Immunosenescence - Review

The body's defense against environmental factors is realized by physical barriers and cells of both the innate and adaptive immune systems. Patients with end stage kidney disease (ESKD), especially those treated by hemodialysis, have changes in both the function and the number or percent of different leukocyte subsets. Changes were described at the level of monocytes and lymphocyte subsets, which are associated with immunodeficiencies and pro-inflammatory status correlated with degenerative changes and increased cardiovascular risk. These abnormalities have been compared over the past years with alterations appearing as a result ageing. Also, similitudes regarding immunosenescence observed in ESKD patients, in combination with chronic inflammation, are described as the so-called "inflammaging syndrome".

Immune response following transcatheter aortic valve procedure

Aortic valve stenosis is the most common type of heart valve disease in the United States and Europe and calcific aortic stenosis (AS) affects 2-7% of people aged 65 years and older. Aortic valve replacement (AVR) is the only effective treatment for individuals with this condition. Transcatheter Aortic Valve Replacement (TAVR) has been widely accepted as a minimally invasive therapeutic approach for addressing symptomatic AS in patients who are considered to have a high risk for traditional surgical intervention. TAVR procedure may have a paradoxical effect on the immune system and inflammatory status. A major portion of these immune responses is regulated by activating or inhibiting inflammatory monocytes and the complement system with subsequent changes in inflammatory cytokines. TAVR has the potential to induce various concurrent exposures, including disruption of the native valve, hemodynamic changes, antigenicity of the bioprosthesis, and vascular damage, which finally lead to the development of inflammation. On the other hand, it is important to acknowledge that TAVR may also have anti-inflammatory effects by helping in the resolution of stenosis.The inflammation and immune response following TAVR are complex processes that significantly impact procedural outcomes and patient well-being. Understanding the underlying mechanisms, identifying biomarkers of inflammation, and exploring therapeutic interventions to modulate these responses are crucial for optimizing TAVR outcomes. Further research is warranted to elucidate the precise immunological dynamics and develop tailored strategies to attenuate inflammation and enhance post-TAVR healing while minimizing complications.

Differential expression patterns of purinergic ectoenzymes and the antioxidative role of IL-6 in hospitalized COVID-19 patient recovery

Introduction

We have acquired significant knowledge regarding the pathogenesis of severe acute respiratory syndrome caused by coronavirus 2 (SARS-CoV-2). However, the underlying mechanisms responsible for disease recovery still need to be fully understood.

Methods

To gain insights into critical immune markers involved in COVID-19 etiopathogenesis, we studied the evolution of the immune profile of peripheral blood samples from patients who had recovered from COVID-19 and compared them to subjects with severe acute respiratory illness but negative for SARS-CoV-2 detection (controls). In addition, linear and clustered correlations between different parameters were determined.

Results

The data obtained revealed a significant reduction in the frequency of inflammatory monocytes (CD14+CD16+) at hospital discharge vs. admission. Remarkably, nitric oxide (NO) production by the monocyte compartment was significantly reduced at discharge. Furthermore, interleukin (IL)-6 plasma levels were negatively correlated with the frequency of NO+CD14+CD16+ monocytes at hospital admission. However, at the time of hospital release, circulating IL-6 directly correlated with the NO production rate by monocytes. In line with these observations, we found that concomitant with NO diminution, the level of nitrotyrosine (NT) on CD8 T-cells significantly diminished at the time of hospital release. Considering that purinergic signaling constitutes another regulatory system, we analyzed the kinetics of CD39 and CD73 ectoenzyme expression in CD8 T-cells. We found that the frequency of CD39+CD8+ T-cells significantly diminished while the percentage of CD73+ cells increased at hospital discharge. In vitro, IL-6 stimulation of PBMCs from COVID-19 patients diminished the NT levels on CD8 T-cells. A clear differential expression pattern of CD39 and CD73 was observed in the NT+ vs. NT-CD8+ T-cell populations.

Discussion

The results suggest that early after infection, IL-6 controls the production of NO, which regulates the levels of NT on CD8 T-cells modifying their effector functions. Intriguingly, in this cytotoxic cell population, the expression of purinergic ectoenzymes is tightly associated with the presence of nitrated surface molecules. Overall, the data obtained contribute to a better understanding of pathogenic mechanisms associated with COVID-19 outcomes.

ICAM-1 and VCAM-1: Gatekeepers in various inflammatory and cardiovascular disorders

Leukocyte migration from the vascular compartment is critical fornormal lymphocyte recirculation in specific tissues and immune response in inflammatory locations. Leukocyte recruitment, migration to inflammatory areas, and targeting in the extravascular space are caused by cellular stimulation and local expression of adhesion molecules. Intercellular adhesion molecule 1 (ICAM-1) and Vascular cell adhesion molecule 1 (VCAM-1) belong to the immunoglobulin superfamily of cell adhesion molecules (CAM) with a crucial role in mediating the strong adherence of leukocytes to endothelial cells in numerous acute as well as chronic diseases. ICAM-1 and VCAM-1 mediate inflammation and promote leukocyte migration during inflammation. ICAM-1 and VCAM-1 have a large role in regulating homeostasis and in pathologic states such as cancer, atherosclerosis, atrial fibrillation, myocardial infarction, stroke, asthma, obesity, kidney diseases, and much more. In inflammatory conditions and infectious disorders, leukocytes move and cling to the endothelium via multiple intracellular adhesive interactions. It is suggested that combining membrane-bound and soluble ICAM-1 and VCAM-1 into a single unit functional system will further our understanding of their immunoregulatory role as well as their pathophysiological effects on disease. This review focuses on the pathophysiological roles of ICAM-1 and VCAM-1 in various inflammatory and other diseases as well as their emerging cardiovascular role during the COVID-19 pandemic.

Target Organ Toxicity in Rats After Subchronic Oral Exposure to Soil Extracts Containing a Complex Mixture of Contaminants

Complex mixtures of unknown contaminants present a challenge to identify toxicological risks without using large numbers of animals and labor-intensive screens of all organs. This study examined soil extracts from a legacy-contaminated pesticide packaging and blending site. HepG2 cytotoxicity was used as an initial screen of 18 soil samples; then, three extracts (A, B and C) from different locations at the study site were used for testing in animals. The first two extracts were identified as the most toxic in vitro, and the latter extract obtained from a location further from these two toxic sampling sites. Then, target organ toxicities were identified following biweekly oral gavage for one month of three soil extracts (0.1% in polyethylene glycol or PEG) compared to vehicle control in male Sprague-Dawley rats (n = 9-10/group). Exposure to extract A significantly increased neutrophils and lymphocytes compared to control. In contrast, all extracts increased plasma α-2 macroglobulin and caused mild-to-moderate lymphocytic proliferation within the spleen white pulp, all indicative of inflammation. Rats exposed to all soil extracts exhibited acute tubular necrosis. Cholinesterase activity was significantly reduced in plasma, but not brain, after exposure to extract A compared to control. Increased hepatic ethoxyresorufin-o-deethylase activity compared to control was observed following exposure to extracts A and B. Exposure to soil extract C in rats showed a prolonged QTc interval in electrocardiography as well as increased brain lipid peroxidation. Candidate contaminants are organochlorine, organophosphate/carbamate pesticides or metabolites. Overall, HepG2 cytotoxicity did not successfully predict the neurotoxicity and cardiotoxicity observed with extract C but was more successful with suspected hydrocarbon toxicities in extracts A and B. Caution should be taken when extrapolating the observation of no effects from in vitro cell culture to in vivo toxicity, and better cell culture lines or assays should be explored.

Update on Innate Immunity in Acute Kidney Injury—Lessons Taken from COVID-19

The serious clinical course of SARS-CoV-2 infection is usually accompanied by acute kidney injury (AKI), worsening prognosis and increasing mortality. AKI in COVID-19 is above all a consequence of systemic dysregulations leading to inflammation, thrombosis, vascular endothelial damage and necrosis. All these processes rely on the interactions between innate immunity elements, including circulating blood cells, resident renal cells, their cytokine products, complement systems, coagulation cascades and contact systems. Numerous simultaneous pathways of innate immunity should secure an effective host defense. Since they all form a network of cross-linked auto-amplification loops, uncontrolled activation is possible. When the actions of selected pathways amplify, cascade activation evades control and the propagation of inflammation and necrosis worsens, accompanied by complement overactivity and immunothrombosis. The systemic activation of innate immunity reaches the kidney, where the damage affecting single tubular cells spreads through tissue collateral damage and triggers AKI. This review is an attempt to synthetize the connections between innate immunity components engaged in COVID-19-related AKI and to summarize the knowledge on the pathophysiological background of processes responsible for renal damage.

Nuanxinkang protects against ischemia/reperfusion-induced heart failure through regulating IKKβ/IκBα/NF-κB-mediated macrophage polarization

BACKGROUND

Heart failure (HF) is a leading cause of death worldwide. Nuanxinkang (NXK) is an effective Chinese herbal formula used in treating HF, but its underlying potential mechanisms have not been fully elucidated.

PURPOSE

To explore the protective activities of NXK in ischemia/reperfusion (IR)-induced HF through modulating the ratio of proinflammatory (M1) and anti-inflammatory (M2) macrophage populations and leading to the alleviation of inflammation.

MATERIALS AND METHODS

In vivo, mice were subjected to myocardial IR to generate HF mouse models. Mice in the NXK group were treated with NXK for 28 days. Cardiac function was detected by echocardiography. Major lesions on mouse hearts were determined by hematoxylin-eosin (HE) staining, Masson staining, and TUNEL staining. Inflammatory cytokines were determined by enzyme-linked immunosorbent assay (ELISA) and qPCR examination. Flow cytometric analyses and qPCR examination were utilized for monitoring the temporal dynamics of macrophage infiltration following IR. In vitro, two polarized models were established by stimulating RAW264.7 cells with 200 ng/ml lipopolysaccharide (LPS) or 20 ng/ml interleukin-4 (IL-4). The RAW264.7 cells with nuclear factor-κB (NF-κB) overexpression was generated by transient transfection of NF-κB plasmids, and NXK intervention was conducted on this cell model to further clarify the involvement of NF-κB signaling in the NXK-mediated HF process.

RESULTS

In the present study, NXK was found to significantly contribute the cardiac function and ameliorate cardiac fibrosis and apoptosis after myocardial IR injury in vivo, which may be partially due to a decrease in inflammation. We therefore hypothesized that NXK reduced inflammatory damage by modulating subtypes of macrophages. And the results demonstrated that the percentage of proinflammatory macrophages infiltrated in the post-IR period was reduced with NXK treatment, and thereby blunting the wave of proinflammatory response and shifting the peak of the anti-inflammatory macrophage-mediated wound healing process towards an earlier time point. The further investigation showed that macrophage polarization was mediated by NXK through inhibiting the phosphorylation and the nuclear translocation of NF-κB. Besides, the phosphorylated IKKβ and IκBα, upstream mediators of the NF-κB pathway, also decreased by NXK. Moreover, the overexpression of NF-κB partially reversed the NXK-induced favorable activities; and successfully compensated the suppressive effect on inflammation and the phosphorylation of NF-κB.

CONCLUSION

In conclude, our results demonstrated that NXK induced the cardioprotective effects against IR injury through a regulatory axis of IKKβ/IκBα/NF-κB-mediated macrophage polarization. The information gained from this study provide a possible natural strategy for anti-inflammatory treatment of HF.

Astragali Radix-Coptis Rhizoma Herb Pair Attenuates Atherosclerosis in ApoE-/- Mice by Regulating the M1/M2 and Th1/Th2 Immune Balance and Activating the STAT6 Signaling Pathway

OBJECTIVE

Immune imbalance and the inflammatory response are associated with atherosclerosis (AS) progression. Astragali Radix and Coptis Rhizoma (ARCR) are an ancient and classic herb pair that is used in herbal medicines for the treatment of coronary heart disease. We focused on the effects and mechanisms of the ARCR herb pair attenuation of atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice.

METHODS

ApoE-/- mice were fed a high-fat diet for 12 weeks to establish a model of AS. The ApoE-/- mice were randomly divided into a model group, simvastatin group (Simva), Astragali Radix group (AR), Coptis Rhizoma group (CR), Astragali Radix-Coptis Rhizoma group (ARCR), and Astragali Radix-Coptis Rhizoma + signal transducer and activator of transcription factor 6 (STAT6) inhibitor (AS1517499) group (ARCR + AS1517499). C57BL/6 mice were used as controls. Each group was administered the corresponding drugs, and mice in the model and control groups were given the same volume of normal saline once daily for 6 weeks. The body weights of the mice were observed regularly. The effect of the ARCR herb pair on lipid content in peripheral blood was evaluated using blood lipid tests. The levels of serum matrix metalloproteinase-9 (MMP-9), interleukins-12 (IL-12), IL-10, interferon-γ (IFN-γ), and IL-4 were determined to assess inflammation. Oil Red O staining, Sirius Red staining, and immunohistochemistry were used to observe changes in plaque stability. Western blotting was used to assay M1/M2 macrophages, Th1/Th2 cells, and STAT6 signaling pathway protein expression. Flow cytometry and immunofluorescence were used to detect M1/M2 macrophages and Th1/Th2 cells and reflect the immune imbalance.

RESULTS

The ARCR herb pair significantly reduced blood lipids levels and plaque vulnerability and regulated the levels of inflammatory factors and the number of M1/M2 macrophages and Th1/Th2 cells in ApoE-/- AS mice. It also decreased iNOS and T-bet protein levels and increased the Arg-1 and GATA-3 protein levels. The ARCR herb pair also increased STAT6 phosphorylation. A STAT6 inhibitor attenuated the regulation of M1/M2 and Th1/Th2 markers induced by the ARCR herb pair.

CONCLUSION

The ARCR herb pair regulates blood lipid metabolism and attenuates atherosclerosis via regulation of M1/M2 and Th1/Th2 immune balance, which is achieved partially by increasing STAT6 phosphorylation. Our study provides new evidence for the possible use of ARCR herb pair in the prevention and treatment of AS.

Beneficial effects of liraglutide on peripheral blood vessels

Background/Aim. Macroangiopathy is the major cause of death and disability in type 2 diabetic patients. Studies have shown that liraglutide, a glucagon-like peptide 1 (GLP-1) receptor agonist, can protect cardiovascular system by inhibiting chronic inflammation of diabetes. However, a study about the effects of liraglutide on peripheral blood vessels and peripheral blood leukocytes has not been reported yet. The aim of this study was to determine vasculoprotective effect, vascular protection and mechanism of action of liraglutide in addition to its hypoglycemic effect. Methods. A total of 60 hospitalized patients with type 2 diabetes were recruited from December 2013 to December 2014 at the First Affiliated Hospital of Dalian Medical University, PR China. Before the treatment with liraglutide, height and weight were measured to calculate body mass index (BMI). Blood urea nitrogen (BUN) and so on were detected. Homeostasis model assessment of insulin resistance (HOMA-IR) and islet ? cell function (HOMA-?) were computed. After applying liraglutide for three months, all indexes were measured again. The effects of liraglutide on these indexes were analyzed by paired sample t-test. Results. After the treatment with liraglutide, values of glycosylated hemoglobin ? HbA1c (8.46 ? 1.62 vs. 7.26 ? 1.40%) and 2h postprandial blood glucose ? 2hPBG (11.95 vs. 9.6 mmol/L) decreased significantly (p < 0.05). Body weight (87.3 vs. 82.5 kg) and BMI (30.37 vs. 28.63 kg/m2) decreased by 5.5% and 5.7%, respectively (p < 0.05). Also, levels of triglycerides (TG) (2.57 ? 1.54 vs. 1.81 ? 0.70 mmol/L) and LDL-cholesterol (2.92 ? 0.78 vs. 1.89 ? 0.66 mmol/L) reduced significantly (p < 0.05). Ankle-brachial index (ABI) decreased from 1.24 ? 0.10 to 1.14 ? 0.06 cm/s by 8%, while brachial-ankle pulse wave velocity (ba-PWV) decreased from 1,442.15 ? 196.26 to 1,316.85 ? 146.63 cm/s by 8.7%, and both differences were statistically significant (p < 0.001). Conclusion. Liraglutide, with a good hypoglycemic effect, can significantly reduce postprandial blood glucose and HbA1c, but cannot significantly improve fasting plasma glucose, insulin resistance and islet ? cell function. It also considerably decreased body weight, BMI and TG. Liraglutide can significantly lower ba-PWV and ABI to protect peripheral blood vessels.

Frailty is associated with chronic inflammation and pro-inflammatory monocyte subpopulations

AIM OF THE STUDY

Frail patients with high grade aortic valve stenosis (AS) undergoing Transcatheter Aortic Valve Implantation (TAVI) have an increased mortality. A connection between frailty and inflammation has been suggested. Monocyte subpopulations are associated with both cardiovascular diseases and chronic inflammatory diseases. This study investigates the association of frailty with monocyte subpopulations and systemic inflammatory parameters in elderly patients undergoing TAVI.

METHODS

A total of 120 patients with symptomatic AS was examined. Before TAVI implantation, frailty was assessed by a bedside evaluation (eyeball test). In all patients a flow cytometry analysis has been performed. Monocyte subpopulations were defined as follows: classical (CD14⁺⁺CD16^-), intermediate (CD14⁺⁺CD16⁺) and non-classical (CD14⁺CD16⁺⁺). Expression of CD11b was measured as a marker for monocyte activation. Pro-inflammatory cytokines such as interleukin IL-8, as well as CRP were measured with Cytometric Bead Array or standard laboratory methods.

RESULTS

28 out of 120 patients were frail. These patients showed both, signs of elevated chronic systemic inflammation reflected by elevated CRP (3.7 (1.4-5.4) vs. 5.9 (3.7-29.1), p = 0.001) and an elevated level of intermediate monocytes (37 (24-54) vs. 53 (47-63), p = 0.001). At 6 months after TAVI, 19 of 120 patients died, primarily without relevant dysfunction of the implanted aortic valve. Mortality was significantly higher in the frail as compared with non-frail patients (9 of 28 frail patients vs. 10 of 92 non frail patients, p < 0.001). A binary logistic regression analysis validated frailty and intermediate monocytes as independent predictors for early mortality after TAVI.

CONCLUSION

Chronic systemic inflammation and increased levels of intermediate monocytes are associated with frailty in old patients with severe aortic valve stenosis. Both the syndrome of frailty and elevated intermediate monocytes showed an association with early mortality after TAVI.

Cardioprotective Effects of Latifolin Against Doxorubicin-Induced Cardiotoxicity by Macrophage Polarization in Mice

Latifolin, one of the major flavonoids extracted from lignum dalbergiae odoriferae, has been documented to protect the heart from acute myocardial ischemia induced by pituitrin and isoproterenol in rats and has also been found to inhibit inflammation. In this study, we aimed to investigate whether latifolin could protect the heart from doxorubicin (DOX)-induced cardiotoxicity and elucidate its underlying mechanisms. Male mice were treated with an intraperitoneal dose of DOX (20 mg/kg) plus oral latifolin at a dose of 50 or 100 mg/kg for 12 days. After exposure, we assessed cardiac function, myocardial injury, and macrophage polarization in excised cardiac tissue. Our results demonstrated that latifolin prevented DOX-induced cardiac dysfunction and produced macrophage polarization in mice challenged with latifolin. In cultured peritoneal macrophages, latifolin significantly reduced inflammatory cytokines (P < 0.05). Furthermore, latifolin remarkably decreased the percentage of macrophage M1/M2 polarization (P < 0.05). The results from the present study highlight the benefits of treatment with latifolin in DOX-induced cardiotoxicity, and the mechanism involved in mediating the polarization phenotype change of M1/M2 macrophages.

IL-10-Dependent and -Independent Mechanisms Are Involved in the Cardiac Pathology Modulation Mediated by Fenofibrate in an Experimental Model of Chagas Heart Disease

IL-10 is an anti-inflammatory cytokine that plays a significant role in the modulation of the immune response in many pathological conditions, including infectious diseases. Infection with Trypanosoma cruzi (T. cruzi), the etiological agent of Chagas disease, results in an ongoing inflammatory response that may cause heart dysfunction, ultimately leading to heart failure. Given its infectious and inflammatory nature, in this work we analyzed whether the lack of IL-10 hinders the anti-inflammatory effects of fenofibrate, a PPARα ligand, in a murine model of Chagas heart disease (CHD) using IL-10 knockout (IL-10 KO) mice. Our results show fenofibrate was able to restore the abnormal cardiac function displayed by T. cruzi-infected mice lacking IL-10. Treatment with fenofibrate reduced creatine kinase (CK) levels in sera of IL-10 KO mice infected with T. cruzi. Moreover, although fenofibrate could not modulate the inflammatory infiltrates developing in the heart, it was able to reduce the increased collagen deposition in infected IL-10 KO mice. Regarding pro-inflammatory mediators, the most significant finding was the increase in serum IL-17. These were reduced in IL-10 KO mice upon fenofibrate treatment. In agreement with this, the expression of RORγt was reduced. Infection of IL-10 KO mice increased the expression of YmI, FIZZ and Mannose Receptor (tissue healing markers) that remained unchanged upon treatment with fenofibrate. In conclusion, our work emphasizes the role of anti-inflammatory mechanisms to ameliorate heart function in CHD and shows, for the first time, that fenofibrate attains this through IL-10-dependent and -independent mechanisms.

TLR4 agonist protects against Trypanosoma cruzi acute lethal infection by decreasing cardiac parasite burdens

E6020 is a synthetic agonist of Toll-like receptor-4 (TLR4). The purpose of this study was to evaluate the effect of different doses of E6020-SE on Trypanosoma cruzi-specific immune responses and its ability to confer protection against acute lethal infection in mice. Forty female BALB/c were infected with 500 trypomastigotes of T cruzi H1 strain, divided into four groups (n = 10) and treated at 7- and 14-day post-infection (dpi) with different doses of E6020-SE or PBS (control). Survival was followed for 51 days, mice were euthanized and hearts were collected to evaluate parasite burden, inflammation and fibrosis. We found significantly higher survival and lower parasite burdens in mice injected with E6020-SE at all doses compared to the control group. However, E6020-SE treatment did not significantly reduce cardiac inflammation or fibrosis. On the other hand, E6020-SE modulated Th1 and Th2 cytokines, decreasing IFN-γ and IL-4 in a dose-dependent manner after stimulation with parasite antigens. We conclude that E6020-SE alone increased survival by decreasing cardiac parasite burdens in BALB/c mice acutely infected with T cruzi but failed to prevent cardiac damage. Our results suggest that for optimal protection, a vaccine antigen is necessary to balance and orient a protective immune response.

Investigation of a combination of amiodarone and itraconazole for treatment of American trypanosomiasis (Chagas disease) in dogs

OBJECTIVE

To evaluate clinical, serologic, parasitological, and histologic outcomes of dogs with naturally occurring Trypanosoma cruzi infection treated for 12 months with amiodarone and itraconazole.

ANIMALS

121 dogs from southern Texas and southern Louisiana.

PROCEDURES

Treatment group dogs (n = 105) received a combination of amiodarone hydrochloride (approx 7.5 mg/kg [3.4 mg/lb], PO, q 24 h, with or without a loading dosage protocol) and itraconazole (approx 10 mg/kg [4.5 mg/lb], PO, q 24 h, adjusted to maintain a plasma concentration of 1 to 2 μg/mL) for 12 months. Control group dogs (n = 16) received no antitrypanosomal medications. Serologic assays for anti-T cruzi antibodies, PCR assays for T cruzi DNA in blood, and physical evaluations were performed 1, 6, 9, 12, and 24 months after study initiation. Adverse events were recorded. Outcomes of interest were recorded and compared between groups.

RESULTS

86 of 105 treatment group dogs and 8 of 16 control group dogs survived and completed the study (5/19 and 6/7 deaths of treatment and control group dogs, respectively, were attributed to T cruzi infection). Mean survival time until death attributed to T cruzi was longer (23.19 vs 15.64 months) for the treatment group. Results of PCR assays were negative for all (n = 92) tested treatment group dogs (except for 1 dog at 1 time point) from 6 to 24 months after study initiation. Clinical improvement in ≥ 1 clinical sign was observed in 53 of 54 and 0 of 10 treatment and control group dogs, respectively; adverse drug events were minor and reversible.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested efficacy of this trypanocidal drug combination for the treatment of T cruzi infection in dogs.

HIF-1α and CD73 expression in cardiac leukocytes correlates with the severity of myocarditis in end-stage Chagas disease patients

Chronic Chagas cardiomyopathy is the main infectious myocarditis worldwide. Almost 30% of Trypanosoma cruzi infected individuals develop slow and progressive myocarditis that leads to ventricular dilation and heart failure. Heart transplantation is an established, valuable therapeutic option for end-stage Chagas disease patients. Although the pathophysiology of Chagas disease has been addressed for decades by numerous groups, the cardiac immunologic mechanisms involved in the progression of clinical manifestation are still unknown. Growing evidence demonstrates that hypoxia-inducible factor (HIF)-1α plays indispensable roles in driving immune response by triggering the expression of CD73 purinergic ecto-enzyme. Purinergic system controls the duration and magnitude of purine signals directed to modulate immune cells through the conversion of extracellular ATP (microbicide/proinflammatory) to the immunoregulatory metabolite adenosine. In the present work, we described that infiltrating leukocytes within cardiac explants from patients with end-stage Chagas cardiomyopathy up-regulated HIF-1α and CD73 expression. Moreover, the number of HIF-1α+ and CD73+ leukocytes positively correlated with the myocarditis severity and the local parasite load. Furthermore, we demonstrated a direct relationship between tissue parasite persistence and the influx of immune cells to the infected hearts, which ultimately determine the severity of the myocarditis. These findings provide evidence that CD73-dependent regulatory pathways are locally triggered in the myocardium of patients with end-stage Chagas disease.

Harmful chemicals emitted from electronic cigarettes and potential deleterious effects in the oral cavity

Use of electronic nicotine delivery systems (ENDS), such as electronic cigarettes (e-cigs), is increasing across the US population and is particularly troubling due to their adoption by adolescents, teens, and young adults. The industry’s marketing approach for these instruments of addiction has been to promote them as a safer alternative to tobacco, a behavioral choice supporting smoking cessation, and as the ‘cool’ appearance of vaping with flavored products (e.g. tutti frutti, bubble gum, and buttered popcorn etc.). Thus, there is a clear need to better document the health outcomes of e-cig use in the oral cavity of the addicted chronic user. There appears to be an array of environmental toxins in the vapors, including reactive aldehydes and carbonyls resulting from the heating elements action on fluid components, as well as from the composition of chemical flavoring agents. The chemistry of these systems shows that the released vapors from the e-cigs frequently contain levels of environmental toxins that considerably exceed federal occupational exposure limits. Additionally, the toxicants in the vapors appear to be retained in the host fluids/tissues at levels often approximating 90% of the levels in the e-cig vapors. These water-soluble reactive toxins can challenge the oral cavity constituents, potentially contributing to alterations in the autochthonous microbiome and host cells critical for maintaining oral homeostasis. This review updates the existing chemistry/environmental aspects of e-cigs, as well as providing an overview of the somewhat limited data on potential oral health effects that could occur across the lifetime of daily e-cig users.

Dysregulation of glycerophospholipid metabolism during Behçet's disease contributes to a pro-inflammatory phenotype of circulating monocytes

Behçet's disease (BD) is a relapsing, multisystem and inflammatory condition characterized by systemic vasculitis of small and large vessels. Although the etiopathogenesis of BD remains unknown, immune-mediated mechanisms play a major role in the development of the disease. BD patients present leukocyte infiltration in the mucocutaneous lesions as well as neutrophil hyperactivation. In contrast to neutrophils, whose involvement in the pathogenesis of BD has been extensively studied, the biology of monocytes during BD is less well known. In this study, we analyzed the phenotype and function of circulating monocytes of 38 BD patients from Hospital of Braga. In addition, we evaluated the impact of inflammatory and metabolomic plasma environment on monocyte biology. We observed a worsening of mitochondrial function, with lower mitochondrial mass and increased ROS production, on circulating monocytes of BD patients. Incubation of monocytes from healthy donors with the plasma of BD patients mimicked the observed phenotype, strongly suggesting the involvement of serum mediators. BD patients, regardless of their symptoms, had higher serum pro-inflammatory TNF-α and IP-10 levels and IL-1β/IL-1RA ratio. Untargeted metabolomic analysis identified a dysregulation of glycerophospholipid metabolism on BD patients, where a significant reduction of phospholipids was observed concomitantly with an increase of lysophospholipids and fatty acids. These observations converged to an enhanced phospholipase A2 (PLA2) activation. Indeed, inhibition of PLA2 with dexamethasone or the downstream cyclooxygenase (COX) enzyme with ibuprofen was able to significantly revert the mitochondrial dysfunction observed on monocytes of BD patients. Our results show that the plasma inflammatory environment coupled with a dysregulation of glycerophospholipid metabolism in BD patients contribute to a dysfunction of circulating monocytes.

A Combination of Itraconazole and Amiodarone Is Highly Effective against Trypanosoma cruzi Infection of Human Stem Cell-Derived Cardiomyocytes

Trypanosoma cruzi is the etiologic agent of Chagas disease (CD), which can result in severe cardiomyopathy. Trypanosoma cruzi is endemic to the Americas, and of particular importance in Latin America. In the United States and other non-endemic countries, rising case numbers have also been observed. The currently used drugs are benznidazole (BNZ) and nifurtimox, which have limited efficacy during chronic infection. We repurposed itraconazole (ICZ), originally an antifungal, in combination with amiodarone (AMD), an antiarrhythmic, with the goal of interfering with T. cruzi infection. Human pluripotent stem cells (hiPSCs) were differentiated into cardiomyocytes (hiPSC-CMs). Vero cells or hiPSC-CMs were infected with T. cruzi trypomastigotes of the II or I strain in the presence of ICZ and/or AMD. After 48 hours, cells were Giemsa stained, and infection and multiplication were evaluated microscopically. Trypanosoma cruzi infection and multiplication were evalutated also by electron microscopy. BNZ was used as a reference compound. Cell metabolism in the presence of test substances was assessed. Itraconazole and AMD showed strain- and dose-dependent interference with T. cruzi infection and multiplication in Vero cells or hiPSC-CMs. Combinations of ICZ and AMD were more effective against T. cruzi than the single substances, or BNZ, without affecting host cell metabolism, and better preserving host cell integrity during infection. Our in vitro data in hiPSC-CMs suggest that a combination of ICZ and AMD might serve as a treatment option for CD in patients, but that different responses due to T. cruzi strain differences have to be taken into account.

Pyridinecarboxylic Acid Derivative Stimulates Pro-Angiogenic Mediators by PI3K/AKT/mTOR and Inhibits Reactive Nitrogen and Oxygen Species and NF-κB Activation Through a PPARγ-Dependent Pathway in T. cruzi-Infected Macrophages

Chagas disease is caused by Trypanosoma cruzi infection and represents an important public health concern in Latin America. Macrophages are one of the main infiltrating leukocytes in response to infection. Parasite persistence could trigger a sustained activation of these cells, contributing to the damage observed in this pathology, particularly in the heart. HP₂₄, a pyridinecarboxylic acid derivative, is a new PPARγ ligand that exerts anti-inflammatory and pro-angiogenic effects. The aim of this work was to deepen the study of the mechanisms involved in the pro-angiogenic and anti-inflammatory effects of HP₂₄ in T. cruzi-infected macrophages, which have not yet been elucidated. We show for the first time that HP₂₄ increases expression of VEGF-A and eNOS through PI3K/AKT/mTOR and PPARγ pathways and that HP₂₄ inhibits iNOS expression and NO release, a pro-inflammatory mediator, through PPARγ-dependent mechanisms. Furthermore, this study shows that HP₂₄ modulates H₂O₂ production in a PPARγ-dependent manner. It is also demonstrated that this new PPARγ ligand inhibits the NF-κB pathway. HP₂₄ inhibits IKK phosphorylation and IκB-α degradation, as well as p65 translocation to the nucleus in a PPARγ-dependent manner. In Chagas disease, both the sustained increment in pro-inflammatory mediators and microvascular abnormalities are crucial aspects for the generation of cardiac damage. Elucidating the mechanism of action of new PPARγ ligands is highly attractive, given the fact that it can be used as an adjuvant therapy, particularly in the case of Chagas disease in which inflammation and tissue remodeling play an important role in the pathophysiology of this disease.

Pro-inflammatory monocyte profile in patients with major depressive disorder and suicide behaviour and how ketamine induces anti-inflammatory M2 macrophages by NMDAR and mTOR

Background

Depression is a highly prevalent disorder that is one of the leading causes of disability worldwide. Despite an unknown aetiology, evidence suggests that the innate and adaptive immune systems play a significant role in the development and maintenance of major depressive disorder (MDD). The non-competitive glutamatergic N-methyl-D-aspartate receptor (NMDAR) antagonist, (R,S)-ketamine (ketamine), has demonstrated rapid and robust efficacy as an antidepressant when administered at sub-anaesthetic doses.

Methods

Our goal was to characterize the pro-inflammatory profile of patients with MDD by measuring pro-inflammatory cytokines in plasma and circulating monocyte subsets and to understand how ketamine induces an anti-inflammatory program in monocyte and macrophages in vitro and vivo.

Finding

Our results show that patients with MDD without other comorbidities (N = 33) exhibited significantly higher levels of pro-inflammatory IL-12 and IL-6 in plasma and that these cytokines were associated with increased numbers of non-classical (CD11b⁺CD16^brightCD14^neg) monocytes and increased activation state (CD40⁺CD86⁺) of classical monocytes in circulation. Remarkably, we have demonstrated that sub-anaesthetic doses of ketamine programs human monocytes into M2c-like macrophages by inducing high levels of CD163 and MERTK with intermediate levels of CD64 and stimulating mTOR-associated gene expression in vitro. The NMDAR antagonist MK-801, but not the α-amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) antagonist, NBQX, also polarizes macrophages to an M2c-like phenotype, but this phenotype disappears upon mTOR pathway inhibition. Sub-anaesthetic doses (10 mg/kg) of ketamine administration in mice both promote reduction of circulating classical pro-inflammatory monocytes and increase of alternative M2 macrophage subtypes in the spleen and CNS.

Interpretation

Our results suggest an anti-inflammatory property of ketamine that can skew macrophages to an M2-like phenotype, highlighting potential therapeutic implications not only for patients with MDD but also other inflammatory-based diseases.

Funding

This study was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT-FONCYT).

Deficiency of CD73 activity promotes protective cardiac immunity against Trypanosoma cruzi infection but permissive environment in visceral adipose tissue

Damaged cells release the pro-inflammatory signal ATP, which is degraded by the ectonucleotidases CD39 and CD73 to the anti-inflammatory mediator adenosine (ADO). The balance between ATP/ADO is known to determine the outcome of inflammation/infection. However, modulation of the local immune response in different tissues due to changes in the balance of purinergic metabolites has yet to be investigated. Here, we explored the contribution of CD73-derived ADO on the acute immune response against Trypanosoma cruzi parasite, which invades and proliferates within different target tissues. Deficiency of CD73 activity led to an enhanced cardiac microbicidal immune response with an augmented frequency of macrophages with inflammatory phenotype and increased CD8+ T cell effector functions. The increment of local inducible nitric oxide (NO) synthase (iNOS)⁺ macrophages and the consequent rise of myocardial NO production in association with reduced ADO levels induced protection against T. cruzi infection as observed by the diminished cardiac parasite burden compared to their wild-type (WT) counterpart. Unexpectedly, parasitemia was substantially raised in CD73KO mice in comparison with WT mice, suggesting the existence of tissue reservoir/s outside myocardium. Indeed, CD73KO liver and visceral adipose tissue (VAT) showed increased parasite burden associated with a reduced ATP/ADO ratio and the lack of substantial microbicidal immune response. These data reveal that the purinergic system has a tissue-dependent impact on the host immune response against T. cruzi infection.

Oxidative Stress and Inflammation, Key Targets of Atherosclerotic Plaque Progression and Vulnerability: Potential Impact of Physical Activity

Atherosclerosis, a complex cardiovascular disease, is a leading cause of mortality and morbidity worldwide. Oxidative stress and inflammation are both involved in the development of atherosclerotic plaque as they increase the biological processes associated with this pathology, such as endothelial dysfunction and macrophage recruitment and adhesion. Atherosclerotic plaque rupture leading to major ischemic events is the result of vulnerable plaque progression, which is a result of the detrimental effect of oxidative stress and inflammation on risk factors for atherosclerotic plaque rupture, such as intraplaque hemorrhage, neovascularization, and fibrous cap thickness. Thus, both are key targets for primary and secondary interventions. It is well recognized that chronic physical activity attenuates oxidative stress in healthy subjects via the improvement of antioxidant enzyme capacities and inflammation via the enhancement of anti-inflammatory molecules. Moreover, it was recently shown that chronic physical activity could decrease oxidative stress and inflammation in atherosclerotic patients. The aim of this review is to summarize the role of oxidative stress and inflammation in atherosclerosis and the results of therapeutic interventions targeting them in both preclinical and clinical studies. The effects of chronic physical activity on these two key processes are then reviewed in vulnerable atherosclerotic plaques in both coronary and carotid arteries.

Monocyte glycolysis determines CD8+ T cell functionality in human Chagas disease

Chagas disease is a lifelong pathology resulting from Trypanosoma cruzi infection. It represents one of the most frequent causes of heart failure and sudden death in Latin America. Herein, we provide evidence that aerobic glycolytic pathway activation in monocytes drives nitric oxide (NO) production, triggering tyrosine nitration (TN) on CD8+ T cells and dysfunction in patients with chronic Chagas disease. Monocytes from patients exhibited a higher frequency of hypoxia-inducible factor 1α and increased expression of its target genes/proteins. Nonclassical monocytes are expanded in patients' peripheral blood and represent an important source of NO. Monocytes entail CD8+ T cell surface nitration because both the frequency of nonclassical monocytes and that of NO-producing monocytes positively correlated with the percentage of TN+ lymphocytes. Inhibition of glycolysis in in vitro-infected peripheral blood mononuclear cells decreased the inflammatory properties of monocytes/macrophages, diminishing the frequency of IL-1β- and NO-producing cells. In agreement, glycolysis inhibition reduced the percentage of TN+CD8+ T cells, improving their functionality. Altogether, these results clearly show that glycolysis governs oxidative stress on monocytes and modulates monocyte-T cell interplay in human chronic Chagas disease. Understanding the pathological immune mechanisms that sustain an inflammatory environment in human pathology is key to designing improved therapies.

Roles of the Mesenchymal Stromal/Stem Cell Marker Meflin in Cardiac Tissue Repair and the Development of Diastolic Dysfunction

RATIONALE

Myofibroblasts have roles in tissue repair following damage associated with ischemia, aging, and inflammation and also promote fibrosis and tissue stiffening, causing organ dysfunction. One source of myofibroblasts is mesenchymal stromal/stem cells that exist as resident fibroblasts in multiple tissues. We previously identified meflin (mesenchymal stromal cell- and fibroblast-expressing Linx paralogue), a glycosylphosphatidylinositol-anchored membrane protein, as a specific marker of mesenchymal stromal/stem cells and a regulator of their undifferentiated state. The roles of meflin in the development of heart disease, however, have not been investigated.

OBJECTIVE

We examined the expression of meflin in the heart and its involvement in cardiac repair after ischemia, fibrosis, and the development of heart failure.

METHODS AND RESULTS

We found that meflin has an inhibitory role in myofibroblast differentiation of cultured mesenchymal stromal/stem cells. Meflin expression was downregulated by stimulation with TGF (transforming growth factor)-β, substrate stiffness, hypoxia, and aging. Histological analysis revealed that meflin-positive fibroblastic cells and their lineage cells proliferated in the hearts after acute myocardial infarction and pressure-overload heart failure mouse models. Analysis of meflin knockout mice revealed that meflin is essential for the increase in the number of cells that highly express type I collagen in the heart walls after myocardial infarction induction. When subjected to pressure overload by transverse aortic constriction, meflin knockout mice developed marked cardiac interstitial fibrosis with defective compensation mechanisms. Analysis with atomic force microscopy and hemodynamic catheterization revealed that meflin knockout mice developed stiff failing hearts with diastolic dysfunction. Mechanistically, we found that meflin interacts with bone morphogenetic protein 7, an antifibrotic cytokine that counteracts the action of TGF-β and augments its intracellular signaling.

CONCLUSIONS

These data suggested that meflin is involved in cardiac tissue repair after injury and has an inhibitory role in myofibroblast differentiation of cardiac fibroblastic cells and the development of cardiac fibrosis.

Adaptive immune cells in calcific aortic valve disease

Calcific aortic valve disease (CAVD) is highly prevalent and has no pharmaceutical treatment. Surgical replacement of the aortic valve has proved effective in advanced disease but is costly, time limited, and in many cases not optimal for elderly patients. This has driven an increasing interest in noninvasive therapies for patients with CAVD. Adaptive immune cell signaling in the aortic valve has shown potential as a target for such a therapy. Up to 15% of cells in the healthy aortic valve are hematopoietic in origin, and these cells, which include macrophages, T lymphocytes, and B lymphocytes, are increased further in calcified specimens. Additionally, cytokine signaling has been shown to play a causative role in aortic valve calcification both in vitro and in vivo. This review summarizes the physiological presence of hematopoietic cells in the valve, innate and adaptive immune cell infiltration in disease states, and the cytokine signaling pathways that play a significant role in CAVD pathophysiology and may prove to be pharmaceutical targets for this disease in the near future.

Analysis of monocitary subpopulations in relation to cardiovascular risk factors

INTRODUCTION

Monocytes play an important role in atherosclerotic progression having both pro and anti-inflammatory effects depending on different circulating monocyte subpopulations. The objective of this study is to characterize these subpopulations and their association with cardiovascular risk factors.

METHODS

Transversal study including 102 selected patients, mean age: 65 years-old (range 41-86), 69% males. A set of specific antibodies against classical monocytes (Mon1, CD14+CD16- CD300e+HLADR+), intermediate (Mon2, CD14+CD16+CD300e+HLADR+) and non-classical (Mon3, CD14-CD16+CD300e+HLADR+) was assayed. Three groups of patients were included: 17 asymptomatic with more than one cardiovascular risk factor (group 1), 56 subjects asymptomatic but with vascular pathology assessed by ultrasound or microalbuminuria (group 2) and 19 patients with a previous atherothrombotic event (group 3). The cardiovascular risk was determined by Framingham and REGICOR scores.

RESULTS

An association between study groups and the percentage of Mon1 and Mon2 was observed (ANOVA, p<.05), being independent of age and sex for Mon2. Likewise Mon1 and Mon2 subpopulations were associated with cardiovascular adverse events (β=0.86, p=.02 y β=0.1 p=.002, respectively), independently of age and sex in the case of Mon2. Moreover the percentage of Mon3 was associated with the presence of several cardiovascular risk factors (β=0.21, p=.04) in the univariate analysis. In addition, there was a correlation between the levels of Mon1 and Mon2 and leukocytes (r=0.7, p<.001 and r=0.26, p=.01, respectively).

CONCLUSIONS

The analysis of monocyte subpopulations may be clinically useful to stratify the inflammatory profile related to the different cardiovascular risk groups.

Isolation and Phenotypic Characterization of Inflammatory Cells from Clinical Samples: Purification of Macrophages from Trypanosoma cruzi-Infected Hearts

Trypanosoma cruzi, the causal agent of chronic Chagas cardiomyopathy, exhibits an important tropism for cardiac tissue. In consequence, T. cruzi experimental infection represents a unique model to study cardiac macrophage behavior and effector functions during either acute or chronic immune response. In this chapter we describe a protocol to isolate immune cells from T. cruzi-infected murine cardiac tissue and to determine the percentage, absolute number, phenotype, and functionality of monocytes and macrophages by using flow cytometry. Moreover, we describe the parameters to discriminate between resident and infiltrating mononuclear phagocytic cells within infected hearts. The investigations in this field will provide mechanistic insights about the roles of these innate immune cells in the context of a clinically relevant target tissue.

Immune mechanisms in the different phases of acute tubular necrosis

Acute kidney injury is a clinical syndrome that can be caused by numerous diseases including acute tubular necrosis (ATN). ATN evolves in several phases, all of which are accompanied by different immune mechanisms as an integral component of the disease process. In the early injury phase, regulated necrosis, damage-associated molecular patterns, danger sensing, and neutrophil-driven sterile inflammation enhance each other and contribute to the crescendo of necroinflammation and tissue injury. In the late injury phase, renal dysfunction becomes clinically apparent, and M1 macrophage-driven sterile inflammation contributes to ongoing necroinflammation and renal dysfunction. In the recovery phase, M2-macrophages and anti-inflammatory mediators counteract the inflammatory process, and compensatory remnant nephron and cell hypertrophy promote an early functional recovery of renal function, while some tubules are still badly injured and necrotic material is removed by phagocytes. The resolution of inflammation is required to promote the intrinsic regenerative capacity of tubules to replace at least some of the necrotic cells. Several immune mechanisms support this wound-healing-like re-epithelialization process. Similar to wound healing, this response is associated with mesenchymal healing, with a profound immune cell contribution in terms of collagen production and secretion of profibrotic mediators. These and numerous other factors determine whether, in the chronic phase, persistent loss of nephrons and hyperfunction of remnant nephrons will result in stable renal function or progress to decline of renal function such as progressive chronic kidney disease.

Gr-1+ Cells Other Than Ly6G+ Neutrophils Limit Virus Replication and Promote Myocardial Inflammation and Fibrosis Following Coxsackievirus B3 Infection of Mice

Coxsackievirus B3 (CVB3) is the primary cause of viral myocarditis. An early and abundant neutrophil accumulation in the myocardium is a hallmark of early CVB3 infection. Yet the relative contribution of neutrophils to host susceptibility to CVB3 myocarditis remains largely unknown. Herein, peripheral neutrophil depletion was implemented in a BALB/c mouse model of acute CVB3 myocarditis using the specific 1A-8 (anti-Ly6G) or a RB6-8C5 (anti-Gr-1) mAb covering a wide range. Anti-Ly6G treatment led to systemic neutropenia throughout the disease, but did not alter virus replication, disease susceptibility and histopathological changes in the heart and pancreas of mice. In contrast, depletion of both neutrophils and monocytes/macrophages by anti-Gr-1 mAb prior to and after infection significantly promoted susceptibility of mice to CVB3 infection which was associated with exacerbated cardiac and pancreatic viral load. However, depletion of Gr1+ cells significantly suppressed acute myocarditis and pancreatic acini destruction at day 7 post infection via reducing Ly6C^high monocyte population in the circulation. Additionally, cardiac interstitial fibrosis was not affected by neutrophil depletion, whereas Gr-1+ cells other than neutrophils increased cardiac fibrosis at day 21 p.i. by increasing cardiac expression of profibrotic cytokine TNF-α and TGF-β. Thus, Neutrophil function is most likely not essential for CVB3 control and peripheral neutrophils play dispensable role in the pathogenesis of acute myocarditis and pancreatitis during CVB3 infection. Whereas Gr-1+ cells other than neutrophils play a major role in limiting viral replication while promoting myocardial and pancreatic inflammatory injury and fibrosis.

Macrophage-Targeted Therapeutics for Metabolic Disease

Macrophages are cells of the innate immune system that are resident in all tissues, including metabolic organs such as the liver and adipose tissue (AT). Because of their phenotypic flexibility, they play beneficial roles in tissue homeostasis, but they also contribute to the progression of metabolic disease. Thus, they are ideal therapeutic targets for diseases such as insulin resistance (IR), nonalcoholic fatty liver disease (NAFLD), and atherosclerosis. Recently, discoveries in the area of drug delivery have facilitated phenotype-specific targeting of macrophages. In this review we discuss advances in potential therapeutics for metabolic diseases via macrophage-specific delivery. We highlight micro- and nanoparticles, liposomes, and oligopeptide complexes, and how they can be used to alter macrophage phenotype for a more metabolically favorable tissue environment.