Identification of splenic reservoir monocytes and their deployment to inflammatory sites

Hypoxia-inducible factor-1α regulates the interleukin-6 production by B cells in rheumatoid arthritis

Objectives

Rheumatoid arthritis (RA) is a disease characterised by bone destruction and systemic inflammation, and interleukin-6 (IL-6) is a therapeutic target for treating it. The study aimed at investigating the sources of IL-6 and the influence of hypoxia-inducible factor-1α (HIF-1α) on IL-6 production by B cells in RA patients.

Methods

The phenotype of IL-6-producing cells in the peripheral blood of RA patients was analysed using flow cytometry. Bioinformatics, real-time polymerase chain reaction, Western blot and immunofluorescence staining were used to determine the IL-6 production and HIF-1α levels in B cells. A dual-luciferase reporter assay and chromatin immunoprecipitation were used to investigate the regulatory role of HIF-1α on IL-6 production in human and mouse B cells.

Results

Our findings revealed that B cells are major sources of IL-6 in the peripheral blood of RA patients, with the proportion of IL-6-producing B cells significantly correlated with RA disease activity. The CD27-IgD+ naïve B cell subset was identified as the typical IL-6-producing subset in RA patients. Both HIF-1α and IL-6 were co-expressed by B cells in the peripheral blood and synovium of RA patients, and HIF-1α was found to directly bind to the IL6 promoter and enhance its transcription.

Conclusion

This study highlights the role of B cells in producing IL-6 and the regulation of this production by HIF-1α in patients with RA. Targeting HIF-1α might provide a new therapeutic strategy for treating RA.

Systemic innate myeloid responses to acute ischaemic and haemorrhagic stroke

Acute ischaemic and haemorrhagic stroke account for significant disability and morbidity burdens worldwide. The myeloid arm of the peripheral innate immune system is critical in the immunological response to acute ischaemic and haemorrhagic stroke. Neutrophils, monocytes, and dendritic cells (DC) contribute to the evolution of pathogenic local and systemic inflammation, whilst maintaining a critical role in ongoing immunity protecting against secondary infections. This review aims to summarise the key alterations to myeloid immunity in acute ischaemic stroke, intracerebral haemorrhage (ICH), and subarachnoid haemorrhage (SAH). By integrating clinical and preclinical research, we discover how myeloid immunity is affected across multiple organ systems including the brain, blood, bone marrow, spleen, and lung, and evaluate how these perturbations associate with real-world outcomes including infection. These findings are placed in the context of the rapidly developing field of human immunology, which offers a wealth of opportunity for further research.

Immune Cells in Cardiac Injury Repair and Remodeling

PURPOSE OF REVIEW

Immune cells are emerging as central cellular components of the heart which communicate with cardiac resident cells during homeostasis, cardiac injury, and remodeling. These findings are contributing to the development and continuous expansion of the new field of cardio-immunology. We review the most recent literature on this topic and discuss ongoing and future efforts to advance this field forward.

RECENT FINDINGS

Cell-fate mapping, strategy depleting, and reconstituting immune cells in pre-clinical models of cardiac disease, combined with the investigation of the human heart at the single cell level, are contributing immensely to our understanding of the complex intercellular communication between immune and non-immune cells in the heart. While the acute immune response is necessary to initiate inflammation and tissue repair post injury, it becomes detrimental when sustained over time and contributes to adverse cardiac remodeling and pathology. Understanding the specific functions of immune cells in the context of the cardiac environment will provide new opportunities for immunomodulation to induce or tune down inflammation as needed in heart disease.

Myocardial Immune Cells: The Basis of Cardiac Immunology

The mammalian heart is characterized by the presence of striated myocytes, which allow continuous rhythmic contraction from early embryonic development until the last moments of life. However, the myocardium contains a significant contingent of leukocytes from every major class. This leukocyte pool includes both resident and nonresident immune cells. Over recent decades, it has become increasingly apparent that the heart is intimately sensitive to immune signaling and that myocardial leukocytes exhibit an array of critical functions, both in homeostasis and in the context of cardiac adaptation to injury. Here, we systematically review current knowledge of all major leukocyte classes in the heart, discussing their functions in health and disease. We also highlight the connection between the myocardium, immune cells, lymphoid organs, and both local and systemic immune responses.

A DUSP6 inhibitor suppresses inflammatory cardiac remodeling and improves heart function after myocardial infarction

Acute myocardial infarction (MI) results in loss of cardiomyocytes and abnormal cardiac remodeling with severe inflammation and fibrosis. However, how cardiac repair can be achieved by timely resolution of inflammation and cardiac fibrosis remains incompletely understood. Our previous findings have shown that dual-specificity phosphatase 6 (DUSP6) is a regeneration repressor from zebrafish to rats. In this study, we found that intravenous administration of the DUSP6 inhibitor (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one (BCI) improved heart function and reduced cardiac fibrosis in MI rats. Mechanistic analysis revealed that BCI attenuated macrophage inflammation through NF-κB and p38 signaling, independent of DUSP6 inhibition, leading to the downregulation of various cytokines and chemokines. In addition, BCI suppressed differentiation-related signaling pathways and decreased bone-marrow cell differentiation into macrophages through inhibiting DUSP6. Furthermore, intramyocardial injection of poly (D, L-lactic-co-glycolic acid)-loaded BCI after MI had a notable effect on cardiac repair. In summary, BCI improves heart function and reduces abnormal cardiac remodeling by inhibiting macrophage formation and inflammation post-MI, thus providing a promising pro-drug candidate for the treatment of MI and related heart diseases. This article has an associated First Person interview with the first author of the paper.

Evaluation of the Effects of Euglena gracilis on Enhancing Immune Responses in RAW264.7 Cells and a Cyclophosphamide-Induced Mouse Model

In this study we evaluated the immune-enhancing effects of β-glucan, the main component of Euglena gracilis (Euglena), and Euglena on inflammatory factor expression in RAW264.7 macrophages and ICR mice with cyclophosphamide-induced immunosuppression. Macrophages were treated with β-glucan or Euglena for 48 h. The β-glucan and Euglena groups exhibited higher levels of inducible nitric oxide synthase, nitric oxide, and tumor necrosis factor (TNF)-α than the control (vehicle alone) group. Animals were fed saline and β-glucan (400 mg/kg body weight (B.W.)) or Euglena (400 or 800 mg/kg B.W.) for 19 days, and on days 17-19, cyclophosphamide (CCP, 80 mg/kg B.W.) was administered to induce immunosuppression in the ICR mouse model. CCP reduced the body weight, spleen index, and cytokine expression of the mice. To measure cytokine and receptor expression, splenocytes were treated with concanavalin A (ConA) or lipopolysaccharide (LPS) as a mitogen for 24 h. In vivo, ConA stimulation significantly upregulated the expression of interferon (IFN)-γ, interleukin (IL)-10, IL-12 receptor β1, IL-1β, and IL-2 in splenocytes from the β-glucan- or Euglena-treated groups compared with those in the splenocytes from the CCP-treated group; LPS stimulation increased the levels of the cytokines TNF-α, IL-1β, and IL-6 in splenocytes from the β-glucan- or Euglena-treated groups compared with those from the CCP-treated group, but most of these differences were not significant. These results demonstrate the effect of Euglena in ameliorating macrophages and immunosuppression in CCP-treated mice. Thus, Euglena has the potential to enhance macrophage- and splenocyte-mediated immune-stimulating responses.

Origin and Heterogeneity of Tissue Myeloid Cells: A Focus on GMP-Derived Monocytes and Neutrophils

Myeloid cells are a significant proportion of leukocytes within tissues, comprising granulocytes, monocytes, dendritic cells, and macrophages. With the identification of various myeloid cells that perform separate but complementary functions during homeostasis and disease, our understanding of tissue myeloid cells has evolved significantly. Exciting findings from transcriptomics profiling and fate-mapping mouse models have facilitated the identification of their developmental origins, maturation, and tissue-specific specializations. This review highlights the current understanding of tissue myeloid cells and the contributing factors of functional heterogeneity to better comprehend the complex and dynamic immune interactions within the healthy or inflamed tissue. Specifically, we discuss the new understanding of the contributions of granulocyte-monocyte progenitor-derived phagocytes to tissue myeloid cell heterogeneity as well as the impact of niche-specific factors on monocyte and neutrophil phenotype and function. Lastly, we explore the developing paradigm of myeloid cell heterogeneity during inflammation and disease.

Untangling Cellular Host-Pathogen Encounters at Infection Bottlenecks

Bacterial pathogens can invade the tissue and establish a protected intracellular niche at the site of invasion that can spread locally (e.g., microcolonies) or to systemic sites (e.g., granulomas). Invasion of the tissue and establishment of intracellular infection are rare events that are difficult to study in the in vivo setting but have critical clinical consequences, such as long-term carriage, reinfections, and emergence of antibiotic resistance. Here, I discuss Salmonella interactions with its host macrophage during early stages of infection and their critical role in determining infection outcome. The dynamics of host-pathogen interactions entail highly heterogenous host immunity, bacterial virulence, and metabolic cross talk, requiring in vivo analysis at single-cell resolution. I discuss models and single-cell approaches that provide a global understanding of the establishment of a protected intracellular niche within the tissue and the host-pathogen landscape at infection bottlenecks during early stages of infection. Studying cellular host-pathogen interactions in vivo can improve our knowledge of the trajectory of infection between the initial inoculation with a dose of pathogens and the appearance of symptoms of disease.

Finding the right tool: a comprehensive evaluation of microglial inducible cre mouse models

The recent proliferation of new Cre and CreER recombinase lines provides researchers with a diverse toolkit to study microglial gene function. To determine how best to apply these lines in studies of microglial gene function, a thorough and detailed comparison of their properties is needed. Here, we examined four different microglial CreER lines (Cx3cr1CreER(Litt), Cx3cr1CreER(Jung), P2ry12CreER, Tmem119CreER), focusing on (1) recombination specificity; (2) leakiness - degree of non-tamoxifen recombination in microglia and other cells; (3) efficiency of tamoxifen-induced recombination; (4) extra-neural recombination -the degree of recombination in cells outside the CNS, particularly myelo/monocyte lineages (5) off-target effects in the context of neonatal brain development. We identify important caveats and strengths for these lines which will provide broad significance for researchers interested in performing conditional gene deletion in microglia. We also provide data emphasizing the potential of these lines for injury models that result in the recruitment of splenic immune cells.

Translation of immunomodulatory therapy to treat chronic heart failure: Preclinical studies to first in human

BACKGROUND

Inflammation has been associated with progression and complications of chronic heart failure (HF) but no effective therapy has yet been identified to treat this dysregulated immunologic state. The selective cytopheretic device (SCD) provides extracorporeal autologous cell processing to lessen the burden of inflammatory activity of circulating leukocytes of the innate immunologic system.

AIM

The objective of this study was to evaluate the effects of the SCD as an extracorporeal immunomodulatory device on the immune dysregulated state of HF. HF.

METHODS AND RESULTS

SCD treatment in a canine model of systolic HF or HF with reduced ejection fraction (HFrEF) diminished leukocyte inflammatory activity and enhanced cardiac performance as measured by left ventricular (LV) ejection fraction and stroke volume (SV) up to 4 weeks after treatment initiation. Translation of these observations in first in human, proof of concept clinical study was evaluated in a patient with severe HFrEFHFrEF ineligible for cardiac transplantation or LV LV assist device (LVAD) due to renal insufficiency and right ventricular dysfunction. Six hour SCD treatments over 6 consecutive days resulted in selective removal of inflammatory neutrophils and monocytes and reduction in key plasma cytokines, including tumor necrosis factor-alpha (TNF-α),), interleukin (IL)-6, IL-8, and monocyte chemoattractant protein (MCP)-1. These immunologic changes were associated with significant improvements in cardiac power output, right ventricular stroke work index, cardiac index and LVSV index…. Stabilization of renal function with progressive volume removal permitted successful LVAD implantation.

CONCLUSION

This translational research study demonstrates a promising immunomodulatory approach to improve cardiac performance in HFrEFHFrEF and supports the important role of inflammation in the progression of HFHF.

Identification and protective role of CD34+ stromal cells/telocytes in experimental autoimmune encephalomyelitis (EAE) mouse spleen

Experimental autoimmune encephalomyelitis (EAE) is a classical animal model of human multiple sclerosis (MS) that is most commonly used to study the neuropathology and therapeutic effects of the disease. Telocytes (TCs) are a specialized type of interstitial or mesenchymal cell first identified by Popescu in various tissues and organs. However, the existence, distribution and role of CD34⁺ stromal cells (SCs)/TCs in the EAE-induced mouse spleen remain to be elucidated. We conducted immunohistochemistry, immunofluorescence (double staining for CD34 and c-kit, vimentin, F4/80, CD163, Nanog, Sca-1, CD31 or tryptase) and transmission electron microscopy experiments to investigate the existence, distribution and role of CD34⁺ SCs/TCs in the EAE-induced mouse spleen. Interestingly, immunohistochemistry, double-immunofluorescence, and transmission electron microscopy results revealed that CD34⁺ SCs/TCs were significantly upregulated in the EAE mouse spleen. Immunohistochemical or double-immunofluorescence staining of CD34⁺ SCs/TCs showed positive expression for CD34, c-kit, vimentin, CD34/vimentin, c-kit/vimentin and CD34/c-kit, and negative expression for CD31 and tryptase. Transmission electron microscopy (TEM) results demonstrated that CD34⁺ SCs/TCs established close connections with lymphocytes, reticular cells, macrophages, endothelial cells and erythrocytes. Furthermore, we also found that M1 (F4/80) or M2 (CD163) macrophages, and haematopoietic, pluripotent stem cells were markedly increased in EAE mice. Our results suggest that CD34⁺ SCs/TCs are abundant and may play a contributing role in modulating the immune response, recruiting macrophages and proliferation of haematopoietic and pluripotent stem cells following injury to promote tissue repair and regeneration in EAE mouse spleens. This suggests that their transplantation combined with stem cells might represent a promising therapeutic target for the treatment and prevention of multiple autoimmune and chronic inflammatory disorders.

Monocyte depletion enhances neutrophil influx and proneural to mesenchymal transition in glioblastoma

Myeloid cells comprise the majority of immune cells in tumors, contributing to tumor growth and therapeutic resistance. Incomplete understanding of myeloid cells response to tumor driver mutation and therapeutic intervention impedes effective therapeutic design. Here, by leveraging CRISPR/Cas9-based genome editing, we generate a mouse model that is deficient of all monocyte chemoattractant proteins. Using this strain, we effectively abolish monocyte infiltration in genetically engineered murine models of de novo glioblastoma (GBM) and hepatocellular carcinoma (HCC), which show differential enrichment patterns for monocytes and neutrophils. Eliminating monocyte chemoattraction in monocyte enriched PDGFB-driven GBM invokes a compensatory neutrophil influx, while having no effect on Nf1-silenced GBM model. Single-cell RNA sequencing reveals that intratumoral neutrophils promote proneural-to-mesenchymal transition and increase hypoxia in PDGFB-driven GBM. We further demonstrate neutrophil-derived TNF-a directly drives mesenchymal transition in PDGFB-driven primary GBM cells. Genetic or pharmacological inhibiting neutrophils in HCC or monocyte-deficient PDGFB-driven and Nf1-silenced GBM models extend the survival of tumor-bearing mice. Our findings demonstrate tumor-type and genotype dependent infiltration and function of monocytes and neutrophils and highlight the importance of targeting them simultaneously for cancer treatments.

Regulated contribution of local and systemic immunity to new bone regeneration by modulating B/Sr concentration of bioactive borosilicate glass

The local immune response induced by bioactive borosilicate glass (BG) plays a vital role in bone regeneration, but its effect in the systemic immune response of distal tissues, such as spleen, remains unknown. In this study, the network structures and the relative theoretical structural descriptors (F_net) of the novel BG composition containing boron (B) and strontium (Sr) were calculated and stimulated by molecular dynamics (MD) simulation, and the linear relationships of F_net and B and Sr releasing rate in pure water and simulate body fluid were built. Next, the synergistic effects of the released B and Sr on promoting osteogenic differentiation, angiogenesis, and macrophage polarization were analyzed in vitro and convinced in rats skull models in vivo. Results show that the optimal synergistic effects of B and Sr both in vitro and in vivo released from 1393B2Sr8 BG increased vessel regeneration, modulated M2 macrophages polarization and promoted new-bone formation. Interestingly, the 1393B2Sr8 BG was found to mobilize monocytes from the spleen to the defects and subsequently modulate them into M2 macrophages. Then, these modulated cells cycled from the bone defects back to the spleen. To analyze the necessity of spleen-derived immune cells in bone regeneration, two contrasting rat models (with/without spleen) of skull defects were furtherly established. As results, rats without spleen had fewer M2 macrophages surrounding skull defects and the bone tissues recovered more slowly, indicating the beneficial effects on bone regeneration of circulating monocytes and polarized macrophages provided by spleen. The present study provides a new approach and strategy in optimizing complex composition of novel BG and sheds light on the importance of spleen through modulating systemic immune response to contribute to local bone regeneration.

Spleen regeneration after subcutaneous heterotopic autotransplantation in a mouse model

BACKGROUND

Splenectomy may lead to severe postoperative complications, including sepsis and cancers. A possible solution to this problem is heterotopic autotransplantation of the spleen. Splenic autografts rapidly restore the regular splenic microanatomy in model animals. However, the functional competence of such regenerated autografts in terms of lympho- and hematopoietic capacity remains uncertain. Therefore, this study aimed to monitor the dynamics of B and T lymphocyte populations, the monocyte-macrophage system, and megakaryocytopoiesis in murine splenic autografts.

METHODS

The model of subcutaneous splenic engraftment was implemented in C57Bl male mice. Cell sources of functional recovery were studied using heterotopic transplantations from B10-GFP donors to C57Bl recipients. The cellular composition dynamics were studied by immunohistochemistry and flow cytometry. Expression of regulatory genes at mRNA and protein levels was assessed by real-time PCR and Western blot, respectively.

RESULTS

Characteristic splenic architecture is restored within 30 days post-transplantation, consistent with other studies. The monocyte-macrophage system, megakaryocytes, and B lymphocytes show the highest rates, whereas the functional recovery of T cells takes longer. Cross-strain splenic engraftments using B10-GFP donors indicate the recipient-derived cell sources of the recovery. Transplantations of scaffolds populated with splenic stromal cells or without them afforded no restoration of the characteristic splenic architecture.

CONCLUSIONS

Allogeneic subcutaneous transplantation of splenic fragments in a mouse model leads to their structural recovery within 30 days, with full reconstitution of the monocyte-macrophage, megakaryocyte and B lymphocyte populations. The circulating hematopoietic cells provide the likely source for the cell composition recovery.

Prognostic significance of spleen shear wave elastography and dispersion in patients with heart failure: the crucial role of cardio-splenic axis

INTRODUCTION

The interaction between the heart and spleen plays a crucial role among cardiac and multiple organ networks, particularly in heart failure (HF). Ultrasound shear wave imaging is a non-invasive technology capable of quantifying tissue quality, but its significance in the spleen in patients with HF is poorly understood.

METHODS AND RESULTS

This prospective observational study enrolled hospitalized 232 patients with HF undergoing abdominal ultrasonography. We used shear wave elastography (SWE) to assess spleen tissue elasticity and shear wave dispersion (SWD) to assess spleen tissue viscosity. Clinical, echocardiography, right heart catheterization, and outcome data were collected. Spleen SWE was negatively correlated with right ventricular fractional area change (R =  - 0.180, P = 0.039), but not with right-sided pressure or congestion indices. When patients were divided into three groups based on tertile values of splenic parameters, Kaplan-Meier analysis demonstrated that patients with the highest spleen SWE and SWD had lower event-free survival rates from cardiac deaths and decompensated HF over a median 494-days follow-up period (P < 0.0001 and P < 0.0001, respectively). In a multivariable Cox proportional hazard model, both spleen SWE and SWD were independently associated with increased risks of adverse cardiac events (hazard ratio, 4.974 and 1.384; P = 0.003 and P < 0.0001). Mechanistically, we evaluated mRNA expressions of CD36, a monocyte/macrophage-associated molecule, in peripheral leukocytes, and found that enhanced spleen stiffness was associated with the upregulation of CD36 expressions.

CONCLUSION

Share wave imaging of the spleen is useful for stratifying the prognosis of HF patients and may suggest a role of the cardio-splenic axis in HF pathogenies.

Rapid neutrophil mobilization by VCAM-1+ endothelial cell-derived extracellular vesicles

AIMS

Acute myocardial infarction rapidly increases blood neutrophils (<2 h). Release from bone marrow, in response to chemokine elevation, has been considered their source, but chemokine levels peak up to 24 h after injury, and after neutrophil elevation. This suggests that additional non-chemokine-dependent processes may be involved. Endothelial cell (EC) activation promotes the rapid (<30 min) release of extracellular vesicles (EVs), which have emerged as an important means of cell-cell signalling and are thus a potential mechanism for communicating with remote tissues.

METHODS AND RESULTS

Here, we show that injury to the myocardium rapidly mobilizes neutrophils from the spleen to peripheral blood and induces their transcriptional activation prior to arrival at the injured tissue. Time course analysis of plasma-EV composition revealed a rapid and selective increase in EVs bearing VCAM-1. These EVs, which were also enriched for miRNA-126, accumulated preferentially in the spleen where they induced local inflammatory gene and chemokine protein expression, and mobilized splenic-neutrophils to peripheral blood. Using CRISPR/Cas9 genome editing, we generated VCAM-1-deficient EC-EVs and showed that its deletion removed the ability of EC-EVs to provoke the mobilization of neutrophils. Furthermore, inhibition of miRNA-126 in vivo reduced myocardial infarction size in a mouse model.

CONCLUSIONS

Our findings show a novel EV-dependent mechanism for the rapid mobilization of neutrophils to peripheral blood from a splenic reserve and establish a proof of concept for functional manipulation of EV-communications through genetic alteration of parent cells.

An intrasplenic injection model of pancreatic cancer metastasis to the liver in mice

Here, we provide a protocol for an intrasplenic injection model to establish pancreatic tumors in the mouse liver. We describe the steps to inject tumor cells into mouse spleen and to perform a splenectomy, followed by animal recovery and end point analysis of tumors in the liver. This model allows rapid and reproducible tumor growth in a clinically relevant metastatic site, providing a platform to evaluate the efficacy of anti-cancer drugs. This technique can be expanded to other cancer cell lines. For complete details on the use and execution of this protocol, please refer to Poh et al. (2022).1.

Development of Spleen Targeting H2S Donor Loaded Liposome for the Effective Systemic Immunomodulation and Treatment of Inflammatory Bowel Disease

Nanoparticles are primarily taken up by immune cells after systemic administration. Thus, they are considered an ideal drug delivery vehicle for immunomodulation. Because the spleen is the largest lymphatic organ and regulates the systemic immune system, there have been studies to develop spleen targeting nanoparticles for immunomodulation of cancer and immunological disorders. Inflammatory bowel disease (IBD) includes disorders involving chronic inflammation in the gastrointestinal tract and is considered incurable despite a variety of treatment options. Hydrogen sulfide (H₂S) is one of the gasotransmitters that carries out anti-inflammatory functions and has shown promising immunomodulatory effects in various inflammatory diseases including IBD. Herein, we developed a delicately tuned H₂S donor delivering liposome for spleen targeting (ST-H₂S lipo) and studied its therapeutic effects in a dextran sulfate sodium (DSS) induced colitis model. We identified the ideal PEG type and ratio of liposome for a high stability, loading efficiency, and spleen targeting effect. In the treatment of the DSS-induced colitis model, we found that ST-H₂S lipo and conventional long-circulating liposomes loaded with H₂S donors (LC-H₂S lipo) reduced the severity of colitis, whereas unloaded H₂S donors did not. Furthermore, the therapeutic effect of ST-H₂S lipo was superior to that of LC-H₂S lipo due to its better systemic immunomodulatory effect than that of LC-H₂S lipo. Our findings demonstrate that spleen targeting H₂S lipo may have therapeutic potential for IBD.

Strategy and application of manipulating DCs chemotaxis in disease treatment and vaccine design

As the most versatile antigen-presenting cells (APCs), dendritic cells (DCs) function as the cardinal commanders in orchestrating innate and adaptive immunity for either eliciting protective immune responses against canceration and microbial invasion or maintaining immune homeostasis/tolerance. In fact, in physiological or pathological conditions, the diversified migratory patterns and exquisite chemotaxis of DCs, prominently manipulate their biological activities in both secondary lymphoid organs (SLOs) as well as homeostatic/inflammatory peripheral tissues in vivo. Thus, the inherent mechanisms or regulation strategies to modulate the directional migration of DCs even could be regarded as the crucial cartographers of the immune system. Herein, we systemically reviewed the existing mechanistic understandings and regulation measures of trafficking both endogenous DC subtypes and reinfused DCs vaccines towards either SLOs or inflammatory foci (including neoplastic lesions, infections, acute/chronic tissue inflammations, autoimmune diseases and graft sites). Furthermore, we briefly introduced the DCs-participated prophylactic and therapeutic clinical application against disparate diseases, and also provided insights into the future clinical immunotherapies development as well as the vaccines design associated with modulating DCs mobilization modes.

Macrophage membrane biomimetic drug delivery system: for inflammation targeted therapy

In recent years, there have been many exciting developments in the biomedical applications of the macrophage membrane bionic drug delivery system (MM-Bio-DDS). Macrophages, as an important immune cell, are involved in initiating and regulating the specific immune response of the body. Therefore, the inflammatory process related to macrophages is an important goal in the diagnosis and treatment of many diseases. In this review, we first summarise the different methods of preparation, characterisation, release profiles and natural advantages of using macrophages as a drug delivery system (DDS). Second, we introduce the processes of various chronic inflammatory diseases and the role of macrophages in them, specifically clarifying how the MM-Bio-DDS provides a wide and effective treatment for the targeted inflammatory site. Finally, based on the existing research, we propose the application prospect and existing challenges of the MM-Bio-DDS, especially the problems in clinical transformation, to provide new ideas for the development and utilisation of the MM-Bio-DDS in targeted drug delivery for inflammation and the treatment of diseases.

Obesity and inflammation influence pharmacokinetic profiles of PEG-based nanoparticles

Most patients that will be treated with soft nanoparticles (NPs) will be obese. Yet, NP testing, which begins with pharmacokinetic (PK) and toxicity studies, is carried out almost exclusively in lean rodents having healthy livers and low inflammation. To address this knowledge gap, we determined the PK and toxicity of tail-vein-injected, PEG-based cylindrical nanoparticles (CNPs) and PEGylated liposomes (PLs) as a function of obesity, liver health, and inflammation in leptin-deficient ob/ob and wild-type C57BL/6 J mice. CNPs localized faster to obese livers than to healthy livers within 24 h of injection. PLs localized faster to obese livers than to healthy livers but only 30 min post-injection. Afterwards PL localization to lean livers was higher than localization to obese livers. Overall, PL liver signal peaked ∼6 h post-injection in lean mice, ∼24 h post-injection in heavy mice, and ∼ 48 h post-injection in obese mice. CNPs and PLs were non-toxic to mouse livers as assessed by histology; they reduced many cytokine and chemokine levels that were elevated by obesity. Liver macrophage depletion reduced CNP and PL liver localization as expected; liver sinusoidal endothelial cell (LSEC) depletion reduced PL liver localization but surprisingly increased CNP liver localization. The intensity of RAW264.7 macrophages was higher after CNP incubations than with PL incubations; conversely, the intensity of LSECs was higher after PL incubations than with CNP incubations. This shows the potential for key differences in NP-liver interactions. Triggering inflammation by administering lipopolysaccharide (LPS) to mice increased CNP liver localization but decreased PL liver localization. The results show that obesity and inflammation in a mouse model and in vitro affect soft PEG-based NP interaction with macrophages and LSECs, but also that these NPs can reduce pro-inflammatory pathways increased by obesity.

Heterogeneous population of macrophages in the development of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by a spectrum of hepatic diseases, including fatty liver, non-alcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma. NAFLD is a hepatic manifestation of metabolic syndrome and has become the leading cause of liver transplantation, necessitating an in-depth understanding of its underlying pathogenic mechanisms and the identification of viable drug targets. Although fatty liver is benign and does not exert marked liver damage or inflammation, NAFLD progression involves inflammatory processes facilitated by immune cells. Macrophages and monocytes constitute the pool of innate immune cells that contribute to NAFLD development in association with other cell types, such as neutrophils, T cells, and natural killer cells. The concept that macrophages contribute to the inflammatory processes in NAFLD development has long been debated; however, the remarkable advances in experimental techniques have rapidly uncovered new subpopulations of macrophages and monocytes, whose functions need to be comprehensively elucidated. The current review focuses on the recent expansion of our knowledge of the heterogeneous population of macrophages crucially involved in NAFLD development. In addition, the present paper discusses ongoing efforts to target macrophages and inflammatory processes to develop optimal therapeutic agents against non-alcoholic steatohepatitis.

PET/MR imaging of inflammation in atherosclerosis

Myocardial infarction, stroke, mental disorders, neurodegenerative processes, autoimmune diseases, cancer and the human immunodeficiency virus impact the haematopoietic system, which through immunity and inflammation may aggravate pre-existing atherosclerosis. The interplay between the haematopoietic system and its modulation of atherosclerosis has been studied by imaging the cardiovascular system and the activation of haematopoietic organs via scanners integrating positron emission tomography and resonance imaging (PET/MRI). In this Perspective, we review the applicability of integrated whole-body PET/MRI for the study of immune-mediated phenomena associated with haematopoietic activity and cardiovascular disease, and discuss the translational opportunities and challenges of the technology.

Modulation of Immunity, Antioxidant Status, Performance, Blood Hematology, and Intestinal Histomorphometry in Response to Dietary Inclusion of Origanum majorana in Domestic Pigeons’ Diet

This experiment was conducted to evaluate the effect of adding Origanum majorana (OM) powder to domestic pigeon diets on growth performance, feeding and drinking behaviour, blood hematology, blood biochemical parameters, blood inflammatory and oxidative markers, carcass characteristics, the weights of lymphoid organs, and and intestinal cecal, and bursa of Fabricius histology. A random distribution of fifty-four unsexed pigeon squabs (30 days old, average body weight; 321 g ± 7.5) into three groups was done. The first group was fed the grower basal diet without adding OM powder, while OM powder was added at levels of 0.5 and 1% to the basal diets of the second and third groups, respectively. The changes in growth performance parameters and feeding and drinking behavior under OM powder’s effect were insignificant. However, the lymphoid organs (spleen and thymus) significantly increased in weight (p < 0.05) in the OM-fed groups. Moreover, blood examination showed positive responses to OM powder in terms of blood cell counts (RBCs andWBCs), and the values of hemoglobin, hematocrit, mean corpuscular volume, lymphocyte numbers, levels of globulin, and glutathione peroxidase enzyme were significantly increased. The numbers of heterophils, the ratio of heterophil to lymphocyte, malondialdehyde levels were reduced (p < 0.05). Histomorphometry examination revealed increases in intestinal villi height, cecal thickness, and bursal follicle area and number. These results indicated that adding OM powder to the pigeon diet may improve their immunity, increase their antioxidant status, and correct some hematological disorders.

Twin-bioengine self-adaptive micro/nanorobots using enzyme actuation and macrophage relay for gastrointestinal inflammation therapy

A wide array of biocompatible micro/nanorobots are designed for targeted drug delivery and precision therapy largely depending on their self-adaptive ability overcoming complex barriers in vivo. Here, we report a twin-bioengine yeast micro/nanorobot (TBY-robot) with self-propelling and self-adaptive capabilities that can autonomously navigate to inflamed sites for gastrointestinal inflammation therapy via enzyme-macrophage switching (EMS). Asymmetrical TBY-robots effectively penetrated the mucus barrier and notably enhanced their intestinal retention using a dual enzyme-driven engine toward enteral glucose gradient. Thereafter, the TBY-robot was transferred to Peyer's patch, where the enzyme-driven engine switched in situ to macrophage bioengine and was subsequently relayed to inflamed sites along a chemokine gradient. Encouragingly, EMS-based delivery increased drug accumulation at the diseased site by approximately 1000-fold, markedly attenuating inflammation and ameliorating disease pathology in mouse models of colitis and gastric ulcers. These self-adaptive TBY-robots represent a safe and promising strategy for the precision treatment of gastrointestinal inflammation and other inflammatory diseases.

Gut-Spleen Axis: Microbiota via Vascular and Immune Pathways Improve Busulfan-Induced Spleen Disruption

Fecal microbiota transplantation (FMT) is an effective means of modulating gut microbiota for the treatment of many diseases, including Clostridioides difficile infections. The gut-spleen axis has been established, and this is involved in the development and function of the spleen. However, it is not understood whether gut microbiota can be used to improve spleen function, especially in spleens disrupted by a disease or an anti-cancer treatment. In the current investigation, we established that alginate oligosaccharide (AOS)-improved gut microbiota (A10-FMT) can rescue anticancer drug busulfan-disrupted spleen vasculature and spleen function. A10-FMT improved the gene and/or protein expression of genes involved in vasculature development, increased the cell proliferation rate, enhanced the endothelial progenitor cell capability, and elevated the expression of the cell junction molecules to increase the vascularization of the spleen. This investigation found for the first time that the reestablishment of spleen vascularization restored spleen function by improving spleen immune cells and iron metabolism. These findings may be used as a strategy to minimize the side effects of anti-cancer drugs or to improve spleen vasculature-related diseases. IMPORTANCE Alginate oligosaccharide (AOS)-improved gut microbiota (A10-FMT) can rescue busulfan disrupted spleen vasculature. A10-FMT improved the cell proliferation rate, endothelial progenitor cell capability, and cell junction molecules to increase vasculature formation in the spleen. This reestablishment restored spleen function by improving spleen immune cells and iron metabolism. These findings are useful for the treatment of spleen vasculature-related diseases.

Ponatinib Drives Cardiotoxicity by S100A8/A9-NLRP3-IL-1β Mediated Inflammation

BACKGROUND

The tyrosine kinase inhibitor ponatinib is the only treatment option for chronic myelogenous leukemia patients with T315I (gatekeeper) mutation. Pharmacovigilance analysis of Food and Drug Administration and World Health Organization datasets has revealed that ponatinib is the most cardiotoxic agent among all Food and Drug Administration-approved tyrosine kinase inhibitors in a real-world scenario. However, the mechanism of ponatinib-induced cardiotoxicity is unknown.

METHODS

The lack of well-optimized mouse models has hampered the in vivo cardio-oncology studies. Here, we show that cardiovascular comorbidity mouse models evidence a robust cardiac pathological phenotype upon ponatinib treatment. A combination of multiple in vitro and in vivo models was employed to delineate the underlying molecular mechanisms.

RESULTS

An unbiased RNA sequencing analysis identified the enrichment of dysregulated inflammatory genes, including a multifold upregulation of alarmins S100A8/A9, as a top hit in ponatinib-treated hearts. Mechanistically, we demonstrate that ponatinib activates the S100A8/A9-TLR4 (Toll-like receptor 4)-NLRP3 (NLR family pyrin domain-containing 3)-IL (interleukin)-1β signaling pathway in cardiac and systemic myeloid cells, in vitro and in vivo, thereby leading to excessive myocardial and systemic inflammation. Excessive inflammation was central to the cardiac pathology because interventions with broad-spectrum immunosuppressive glucocorticoid dexamethasone or specific inhibitors of NLRP3 (CY-09) or S100A9 (paquinimod) nearly abolished the ponatinib-induced cardiac dysfunction.

CONCLUSIONS

Taken together, these findings uncover a novel mechanism of ponatinib-induced cardiac inflammation leading to cardiac dysfunction. From a translational perspective, our results provide critical preclinical data and rationale for a clinical investigation into immunosuppressive interventions for managing ponatinib-induced cardiotoxicity.

Circulating Myeloid Cell-derived Extracellular Vesicles as Mediators of Indirect Acute Lung Injury

Blood-borne myeloid cells, neutrophils and monocytes, play a central role in the development of indirect acute lung injury (ALI) during sepsis and noninfectious systemic inflammatory response syndrome. By contrast, the contribution of circulating myeloid cell-derived extracellular vesicles (EVs) to ALI is unknown, despite acute increases in their numbers during sepsis and systemic inflammatory response syndrome. Here, we investigated the direct role of circulating myeloid-EVs in ALI using a mouse isolated perfused lung system and a human cell coculture model of pulmonary vascular inflammation consisting of lung microvascular endothelial cells and peripheral blood mononuclear cells. Total and immunoaffinity-isolated myeloid (CD11b⁺) and platelet (CD41⁺) EVs were prepared from the plasma of intravenous LPS-injected endotoxemic donor mice and transferred directly into recipient lungs. Two-hour perfusion of lungs with unfractionated EVs from a single donor induced pulmonary edema formation and increased perfusate concentrations of RAGE (receptor for advanced glycation end products), consistent with lung injury. These responses were abolished in the lungs of monocyte-depleted mice. The isolated myeloid- but not platelet-EVs produced a similar injury response and the acute intravascular release of proinflammatory cytokines and endothelial injury markers. In the in vitro human coculture model, human myeloid- (CD11b⁺) but not platelet- (CD61⁺) EVs isolated from LPS-stimulated whole blood induced acute proinflammatory cytokine production and endothelial activation. These findings implicate circulating myeloid-EVs as acute mediators of pulmonary vascular inflammation and edema, suggesting an alternative therapeutic target for attenuation of indirect ALI.

Premorbid Use of Beta-Blockers or Angiotensin-Converting Enzyme Inhibitors/Angiotensin Receptor Blockers in Patients with Acute Ischemic Stroke

This study was designed to investigate the impact of the preexisting use of beta-blockers, angiotensin-converting enzyme inhibitors (ACEIs), or angiotensin receptor blockers (ARBs) on the cellular immune response in peripheral blood and the clinical outcomes of patients with acute ischemic stroke. We retrospectively collected clinical data from a cohort of 69 patients with premorbid beta-blockers and 56 patients with premorbid ACEIs/ARBs. Additionally, we selected a cohort of 107 patients with acute ischemic stroke to be the control of the same age and sex. We analyzed cellular immune parameters in peripheral blood 1 day after the appearance of symptoms, including the frequencies of circulating white blood cell subpopulations, the neutrophil-to-lymphocyte ratio (NLR), and the lymphocyte-to-monocyte ratio (LMR). We found that the count of lymphocytes and the lymphocyte-to-monocyte ratio were significantly higher in the peripheral blood of patients treated with beta-blockers before stroke than in matched controls. However, the premorbid use of ACEIs/ARBs did not considerably impact the circulating immune parameters listed above in patients with acute ischemic stroke. Furthermore, we found that premorbid use of beta-blockers or ACEIs/ARBs did not significantly change functional outcomes in patients 3 months after the onset of stroke. These results suggest that premorbid use of beta-blockers, but not ACEIs/ARBs, reversed lymphopenia associated with acute ischemic stroke. As cellular immune changes in peripheral blood could be an independent predictor of stroke prognosis, more large-scale studies are warranted to further verify the impact of premorbid use of beta-blockers or ACEIs/ARBs on the prognosis of patients with ischemic stroke. Our research is beneficial to understanding the mechanism of the systemic immune response induced by stroke and has the potential for a therapeutic strategy in stroke interventions and treatment.

Macrophages: From Simple Phagocyte to an Integrative Regulatory Cell for Inflammation and Tissue Regeneration-A Review of the Literature

The understanding of macrophages and their pathophysiological role has dramatically changed within the last decades. Macrophages represent a very interesting cell type with regard to biomaterial-based tissue engineering and regeneration. In this context, macrophages play a crucial role in the biocompatibility and degradation of implanted biomaterials. Furthermore, a better understanding of the functionality of macrophages opens perspectives for potential guidance and modulation to turn inflammation into regeneration. Such knowledge may help to improve not only the biocompatibility of scaffold materials but also the integration, maturation, and preservation of scaffold-cell constructs or induce regeneration. Nowadays, macrophages are classified into two subpopulations, the classically activated macrophages (M1 macrophages) with pro-inflammatory properties and the alternatively activated macrophages (M2 macrophages) with anti-inflammatory properties. The present narrative review gives an overview of the different functions of macrophages and summarizes the recent state of knowledge regarding different types of macrophages and their functions, with special emphasis on tissue engineering and tissue regeneration.

Nanoparticle Based Cardiac Specific Drug Delivery

Heart failure secondary to myocardial injuries is a leading cause of death worldwide. Recently, a growing number of novel therapies have emerged for injured myocardium repairment. However, delivering therapeutic agents specifically to the injured heart remains a significant challenge. Nanoparticles are the most commonly used vehicles for targeted drug delivery. Various nanoparticles have been synthesized to deliver drugs and other therapeutic molecules to the injured heart via passive or active targeting approaches, and their targeting specificity and therapeutic efficacies have been investigated. Here, we summarized nanoparticle-based, cardiac-specific drug delivery systems, their potency for treating heart diseases, and the mechanisms underlying these cardiac-targeting strategies. We also discussed the clinical studies that have employed nanoparticle-based cardiac-specific drug delivery.

Dynamic changes of monocytes subsets predict major adverse cardiovascular events and left ventricular function after STEMI

We explored how dynamic changes in monocyte subset counts (as opposed to static values to specific time points), and their phagocytic and NFκB activity relate to major adverse cardiovascular events (MACE) and left ventricular ejection fraction (LVEF) in patients with ST-elevation myocardial infarction (STEMI). Changes in counts, phagocytic activity and intracellular levels of inhibitory κB kinase β (IKKβ) (a marker of NFκB activity) of monocyte subsets (CD14⁺⁺CD16^-CCR2⁺ [Mon1], CD14⁺⁺CD16⁺CCR2⁺ [Mon2] and CD14⁺CD16⁺⁺CCR2^- [Mon3]) were measured by flow cytometry in patients with STEMI at baseline, and again after one week, two weeks, and one month. LVEF was measured by echocardiography at baseline and six months after STEMI. Baseline data included 245 patients (mean ± SD age 60 ± 12 years; 22% female), who were followed for a median of 46 (19-61) months. Multivariate Cox regression demonstrated that more prominent dynamic reduction in Mon2 by week 1 (n = 37) was independently associated with fewer MACE (HR 0.06, 95% CI 0.01-0.55, p = 0.01). Also, less prominent reduction in Mon2 at month 1 (n = 24) was independently predictive of 6-month LVEF. None of the other dynamic changes in monocyte subsets were associated with changes in survival from MACE. Neither phagocytic activity nor IKKβ were associated with survival for each monocyte subset. We showed how distinct pattern of dynamic changes in Mon2 are related to both MACE risk and recovery of cardiac contractility. Further research is needed to understand the mechanism of the monocyte effect and possibilities of their pharmacological manipulation.

Bruton's tyrosine kinase inhibition attenuates disease progression by reducing renal immune cell invasion in mice with hemolytic-uremic syndrome

Hemolytic-uremic syndrome (HUS) can occur as a complication of an infection with Shiga-toxin (Stx)-producing Escherichia coli. Patients typically present with acute kidney injury, microangiopathic hemolytic anemia and thrombocytopenia. There is evidence that Stx-induced renal damage propagates a pro-inflammatory response. To date, therapy is limited to organ-supportive strategies. Bruton's tyrosine kinase (BTK) plays a pivotal role in recruitment and function of immune cells and its inhibition was recently shown to improve renal function in experimental sepsis and lupus nephritis. We hypothesized that attenuating the evoked immune response by BTK-inhibitors (BTKi) ameliorates outcome in HUS. We investigated the effect of daily oral administration of the BTKi ibrutinib (30 mg/kg) and acalabrutinib (3 mg/kg) in mice with Stx-induced HUS at day 7. After BTKi administration, we observed attenuated disease progression in mice with HUS. These findings were associated with less BTK and downstream phospholipase-C-gamma-2 activation in the spleen and, subsequently, a reduced renal invasion of BTK-positive cells including neutrophils. Only ibrutinib treatment diminished renal invasion of macrophages, improved acute kidney injury and dysfunction (plasma levels of NGAL and urea) and reduced hemolysis (plasma levels of bilirubin and LDH activity). In conclusion, we report here for the first time that BTK inhibition attenuates the course of disease in murine HUS. We suggest that the observed reduction of renal immune cell invasion contributes - at least in part - to this effect. Further translational studies are needed to evaluate BTK as a potential target for HUS therapy to overcome currently limited treatment options.

Immune cells drive new immunomodulatory therapies for myocardial infarction: From basic to clinical translation

The high incidence of heart failure secondary to myocardial infarction (MI) has been difficult to effectively address. MI causes strong aseptic inflammation, and infiltration of different immune cells and changes in the local inflammatory microenvironment play a key regulatory role in ventricular remodeling. Therefore, the possibility of improving the prognosis of MI through targeted immunity has been of interest and importance in MI. However, previously developed immune-targeted therapies have not achieved significant success in clinical trials. Here, we propose that the search for therapeutic targets from different immune cells may be more precise and lead to better clinical translation. Specifically, this review summarizes the role and potential therapeutic targets of various immune cells in ventricular remodeling after MI, especially monocytes/macrophages and neutrophils, as a way to demonstrate the importance and potential of immunomodulatory therapies for MI. In addition, we analyze the reasons for the failure of previous immunomodulatory therapies and the issues that need to be addressed, as well as the prospects and targeting strategies of using immune cells to drive novel immunomodulatory therapies, hoping to advance the development of immunomodulatory therapies by providing evidence and new ideas.

The role of macrophage subsets in and around the heart in modulating cardiac homeostasis and pathophysiology

Cardiac and pericardial macrophages contribute to both homeostatic and pathophysiological processes. Recent advances have identified a vast repertoire of these macrophage populations in and around the heart - broadly categorized into a CCR2⁺/CCR2^- dichotomy. While these unique populations can be further distinguished by origin, localization, and other cell surface markers, further exploration into the role of cardiac and pericardial macrophage subpopulations in disease contributes an additional layer of complexity. As such, novel transgenic models and exogenous targeting techniques have been employed to evaluate these macrophages. In this review, we highlight known cardiac and pericardial macrophage populations, their functions, and the experimental tools used to bolster our knowledge of these cells in the cardiac context.

Auriculotherapy Modulates Macrophage Polarization to Reduce Inflammatory Response in a Rat Model of Acne

Background

The inflammatory response is an important part of the pathogenesis of acne vulgaris. Auriculotherapy has been shown to have a good therapeutic effect on this disease. The aim of this study was to explore the mechanism underlying the anti-inflammatory effect of auriculotherapy in the treatment of acne vulgaris.

Methods

Propionibacterium acnes was injected subcutaneously into the ears of rats to establish an animal model of acne. The auriculotherapy intervention in rats consisted of auricular bloodletting therapy (ABT), auricular point sticking (APS), or a combination of both (ABPS). The anti-inflammatory effects of auriculotherapy were evaluated by measuring changes in ear thickness, local body surface microcirculation in the ear, and serum inflammatory factors in rats. The polarization of macrophages was analyzed by flow cytometry, and the expression of TLR2/NF-κB signaling pathway in the target tissues was analyzed using western blot.

Results

ABT, APS, and ABPS all reduced the erythema of ear acne, decreased microcirculation in localized ear acne, and decreased serum levels of TNF-α and IL-1β in rats. Meanwhile, the three interventions reduced M1-type macrophages and increased M2-type macrophages; only APS could reduce the expression of TLR2/NF-κB signaling pathway.

Conclusion

ABT, APS, and ABPS can improve the inflammatory symptoms of acne and reduce inflammatory cytokines. APS may exert anti-inflammatory effects by altering macrophage polarization and decreasing TLR2/NF-κB expression.

Post-Cardiac Arrest: Mechanisms, Management, and Future Perspectives

Cardiac arrest is an important public health issue, with a survival rate of approximately 15 to 22%. A great proportion of these deaths occur after resuscitation due to post-cardiac arrest syndrome, which is characterized by the ischemia-reperfusion injury that affects the role body. Understanding physiopathology is mandatory to discover new treatment strategies and obtain better results. Besides improvements in cardiopulmonary resuscitation maneuvers, the great increase in survival rates observed in recent decades is due to new approaches to post-cardiac arrest care. In this review, we will discuss physiopathology, etiologies, and post-resuscitation care, emphasizing targeted temperature management, early coronary angiography, and rehabilitation.

Splenic arterial neurovascular bundle stimulation in esophagectomy: A feasibility and safety prospective cohort study

INTRODUCTION

The autonomic nervous system is a key regulator of inflammation. Electrical stimulation of the vagus nerve has been shown to have some preclinical efficacy. However, only a few clinical studies have been reported to treat inflammatory diseases. The present study evaluates, for the first time, neuromodulation of the splenic arterial neurovascular bundle (SpA NVB) in patients undergoing minimally invasive esophagectomy (MIE), in which the SpA NVB is exposed as part of the procedure.

METHODS

This single-center, single-arm study enrolled 13 patients undergoing MIE. During the abdominal phase of the MIE, a novel cuff was placed around the SpA NVB, and stimulation was applied. The primary endpoint was the feasibility and safety of cuff application and removal. A secondary endpoint included the impact of stimulation on SpA blood flow changes during the stimulation, and an exploratory point was C-reactive protein (CRP) levels on postoperative day (POD) 2 and 3.

RESULTS

All patients successfully underwent placement, stimulation, and removal of the cuff on the SpA NVB with no adverse events related to the investigational procedure. Stimulation was associated with an overall reduction in splenic arterial blood flow but not with changes in blood pressure or heart rate. When compared to historic Propensity Score Matched (PSM) controls, CRP levels on POD2 (124 vs. 197 mg/ml, p = 0.032) and POD3 (151 vs. 221 mg/ml, p = 0.033) were lower in patients receiving stimulation.

CONCLUSION

This first-in-human study demonstrated for the first time that applying a cuff around the SpA NVB and subsequent stimulation is safe, feasible, and may have an effect on the postoperative inflammatory response following MIE. These findings suggest that SpA NVB stimulation may offer a new method for immunomodulatory therapy in acute or chronic inflammatory conditions.

Quo Vadis? Immunodynamics of Myeloid Cells after Myocardial Infarction

Myocardial infarction (MI), a major contributor to worldwide morbidity and mortality, is caused by a lack of blood flow to the heart. Affected heart tissue becomes ischemic due to deficiency of blood perfusion and oxygen delivery. In case sufficient blood flow cannot be timely restored, cardiac injury with necrosis occurs. The ischemic/necrotic area induces a systemic inflammatory response and hundreds of thousands of leukocytes are recruited from the blood to the injured heart. The blood pool of leukocytes is rapidly depleted and urgent re-supply of these cells is needed. Myeloid cells are generated in the bone marrow (BM) and spleen, released into the blood, travel to sites of need, extravasate and accumulate inside tissues to accomplish various functions. In this review we focus on the "leukocyte supply chain" and will separately evaluate different myeloid cell compartments (BM, spleen, blood, heart) in steady state and after MI. Moreover, we highlight the local and systemic kinetics of extracellular factors, chemokines and danger signals involved in the regulation of production/generation, release, transportation, uptake, and activation of myeloid cells during the inflammatory phase of MI.

Circulating monocytes in acute pancreatitis

Acute pancreatitis is a common gastrointestinal disease characterized by inflammation of the exocrine pancreas and manifesting itself through acute onset of abdominal pain. It is frequently associated with organ failure, pancreatic necrosis, and death. Mounting evidence describes monocytes - phagocytic, antigen presenting, and regulatory cells of the innate immune system - as key contributors and regulators of the inflammatory response and subsequent organ failure in acute pancreatitis. This review highlights the recent advances of dynamic change of numbers, phenotypes, and functions of circulating monocytes as well as their underling regulatory mechanisms with a special focus on the role of lipid modulation during acute pancreatitis.

Pro-haemostatic effect of DDAVP is partially derived through non-classical (CD14dim /CD16++ ) monocytes residing the spleen

The splenic endothelial Weibel-palade bodies are one of the most important candidate organelles to release von Willebrand factor upon stimulation with desmopressin. However, the presence of functional desmopressin-specific receptor has not yet been demonstrated on endothelial cells. Experimental evidences are in favour of an indirect pro-haemostatic effect of desmopressin, but the exact mediator and its cellular origin are largely elusive. Here, we report partially hampered desmopressin response in a splenectomised severe haemophilia A/Beta Thalassemia patient without any genetic variant relevant to his incomplete desmopressin response. To further investigate the role of the spleen in this phenomenon, the release of VWF from desmopressin-treated human splenic endothelial cells was assessed in vitro. As a result, desmopressin induced the release of VWF from endothelial cells when the cells were co-cultured with non-classical (CD14^dim /CD16⁺⁺ ), but not other subtypes of monocytes or PBMCs. This in vitro study which resembles close proximity of endothelial cells of sinusoids to monocyte reservoir reside in parenchyma of subcapsular red pulp of the spleen sheds a light upon the role of this highly vascularized VWF-producing organ in driving indirect effect of desmopressin.

High-impact opportunities to address ischemia: a focus on heart and circulatory research

Myocardial ischemic injury and its resolution are the key determinants of morbidity or mortality in heart failure. The cause and duration of ischemia in patients vary. Numerous experimental models and methods have been developed to define genetic, metabolic, molecular, cellular, and pathophysiological mechanisms, in addition to defining structural and functional deterioration of cardiovascular performance. The rapid rise of big data, such as single-cell analysis techniques with bioinformatics, machine learning, and neural networking, brings a new level of sophistication to our understanding of myocardial ischemia. This mini-review explores the multifaceted nature of ischemic injury in the myocardium. We highlight recent state-of-the-art findings and strategies to show new directions of high-impact approach to understanding myocardial tissue remodeling. This next age of heart and circulatory physiology research will be more comprehensive and collaborative to uncover the origin, progression, and manifestation of heart failure while strengthening novel treatment strategies.

High-dimensional intravital microscopy reveals major changes in splenic immune system during postnatal development

Spleen is a key organ for immunologic surveillance, acting as a firewall for antigens and parasites that spread through the blood. However, how spleen leukocytes evolve across the developmental phase, and how they spatially organize and interact in vivo is still poorly understood. Using a novel combination of selected antibodies and fluorophores to image in vivo the spleen immune environment, we described for the first time the dynamics of immune development across postnatal period. We found that spleens from adults and infants had similar numbers and arrangement of lymphoid cells. In contrast, splenic immune environment in newborns is sharply different from adults in almost all parameters analysed. Using this in vivo approach, B cells were the most frequent subtype throughout the development. Also, we revealed how infections - using a model of malaria - can change the spleen immune profile in adults and infants, which could become the key to understanding different severity grades of infection. Our new imaging solutions can be extremely useful for different groups in all areas of biological investigation, paving a way for new intravital approaches and advances.

The therapeutic potential of bone marrow-derived macrophages in neurological diseases

Circulating monocytes are precursors of both tissue macrophages and dendritic cells, and they can infiltrate the central nervous system (CNS) where they transform into bone marrow-derived macrophages (BMDMs). BMDMs play essential roles in various CNS diseases, thus modulating BMDMs might be a way to treat these disorders because there are currently no efficient therapeutic methods available for most of these neurological diseases. Moreover, BMDMs can serve as promising gene delivery vehicles following bone marrow transplantation for otherwise incurable genetic CNS diseases. Understanding the distinct roles that BMDMs play in CNS diseases and their potential as gene delivery vehicles may provide new insights and opportunities for using BMDMs as therapeutic targets or delivery vehicles. This review attempts to comprehensively summarize the neurological diseases that might be treated by modulating BMDMs or by delivering gene therapies via BMDMs after bone marrow transplantation.

Traumatic brain injury with concomitant injury to the spleen: characteristics and mortality of a high-risk trauma cohort from the TraumaRegister DGU®

PURPOSE

Based on the hypothesis that systemic inflammation contributes to secondary injury after initial traumatic brain injury (TBI), this study aims to describe the effect of splenectomy on mortality in trauma patients with TBI and splenic injury.

METHODS

A retrospective cohort analysis of patients prospectively registered into the TraumaRegister DGU® (TR-DGU) with TBI (AISHead ≥ 3) combined with injury to the spleen (AISSpleen ≥ 1) was conducted. Multivariable logistic regression modeling was performed to adjust for confounding factors and to assess the independent effect of splenectomy on in-hospital mortality.

RESULTS

The cohort consisted of 1114 patients out of which 328 (29.4%) had undergone early splenectomy. Patients with splenectomy demonstrated a higher Injury Severity Score (median: 34 vs. 44, p < 0.001) and lower Glasgow Coma Scale (median: 9 vs. 7, p = 0.014) upon admission. Splenectomized patients were more frequently hypotensive upon admission (19.8% vs. 38.0%, p < 0.001) and in need for blood transfusion (30.3% vs. 61.0%, p < 0.001). The mortality was 20.7% in the splenectomy group and 10.3% in the remaining cohort. After adjustment for confounding factors, early splenectomy was not found to exert a significant effect on in-hospital mortality (OR 1.29 (0.67-2.50), p = 0.45).

CONCLUSION

Trauma patients with TBI and spleen injury undergoing splenectomy demonstrate a more severe injury pattern, more compromised hemodynamic status and higher in-hospital mortality than patients without splenectomy. Adjustment for confounding factors reveals that the splenectomy procedure itself is not independently associated with survival.

Divergent roles of PD-L1 in immune regulation during ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury is a type of pathological injury that commonly arises in various diseases. Various forms of immune response are involved in the process of I/R injury. As a member of the B7 costimulatory molecule family, programmed death 1-ligand 1 (PD-L1) is an important target for immune regulation. Therefore, PD-L1 may be implicated in the regulation of I/R injury. This review briefly describes the immune response during I/R injury and how PD-L1 is involved in its regulation by focusing on findings from various I/R models. Despite the limited number of studies in this field of research, PD-L1 has shown sufficient potential as a clinical therapeutic target.

Accelerating cutaneous healing in a rodent model of type II diabetes utilizing non-invasive focused ultrasound targeted at the spleen

Healing of wounds is delayed in Type 2 Diabetes Mellitus (T2DM), and new treatment approaches are urgently needed. Our earlier work showed that splenic pulsed focused ultrasound (pFUS) alters inflammatory cytokines in models of acute endotoxemia and pneumonia via modulation of the cholinergic anti-inflammatory pathway (CAP) (ref below). Based on these earlier results, we hypothesized that daily splenic exposure to pFUS during wound healing would accelerate closure rate via altered systemic cytokine titers. In this study, we applied non-invasive ultrasound directed to the spleen of a rodent model [Zucker Diabetic Sprague Dawley (ZDSD) rats] of T2DM with full thickness cutaneous excisional wounds in an attempt to accelerate wound healing via normalization of T2DM-driven aberrant cytokine expression. Daily (1x/day, Monday-Friday) pFUS pulses were targeted externally to the spleen area for 3 min over the course of 15 days. Wound diameter was measured daily, and levels of cytokines were evaluated in spleen and wound bed lysates. Non-invasive splenic pFUS accelerated wound closure by up to 4.5 days vs. sham controls. The time to heal in all treated groups was comparable to that of healthy rats from previously published studies (ref below), suggesting that the pFUS treatment restored a normal wound healing phenotype to the ZDSD rats. IL-6 was lower in stimulated spleen (-2.24 ± 0.81 Log2FC, p = 0.02) while L-selectin was higher in the wound bed of stimulated rodents (2.53 ± 0.72 Log2FC, p = 0.003). In summary, splenic pFUS accelerates healing in a T2DM rat model, demonstrating the potential of the method to provide a novel, non-invasive approach for wound care in diabetes.

Chitin Derived Small Molecule AVR-48 Reprograms the Resting Macrophages to an Intermediate Phenotype and Decrease Pseudomonas aeruginosa Mouse Lung Infection

AVR-48 is a structural derivative of chitin previously shown by our laboratory to significantly decrease lung injury parameters in LPS, hyperoxia and sepsis-induced rodent models. The current study objectives are to determine the cellular mechanism of action and demonstrate efficacy in a mouse bacterial lung infection model. For in vitro receptor binding and macrophage polarization studies, C57Bl/6J mouse derived spleens and human peripheral blood mononuclear cells (hPBMCs) were treated with AVR-48 ± LPS or biotin conjugated AVR-48. Different macrophage types were determined using flow cytometry and secreted cytokines were measured using ELISA. In vivo, a CD-1 mouse Pseudomonas aeruginosa lung infection was treated with AVR-48, assessing bacterial colony forming unit (CFU), IL-10 and IL-17A levels in lung and blood samples. AVR-48 binds to both the toll-like receptor 4 (TLR4) and the CD163 receptor on mouse monocytes. In hPBMCs, frequency of intermediate macrophages increased upon AVR-48 treatment for 72 h. Increased bacterial phagocytosis/intracellular killing were observed in THP-1 cells and reduction in CFU in CD-1 mouse lungs. Binding of AVR-48 to both TLR4 and CD163 receptors bring the macrophages to an intermediary stage, resulting in increased phagocytosis and decreased inflammation, altogether providing an optimal immune balance for treating lung injury and infection.

The neuroimmunology of social-stress-induced sensitization

Myriad clinical findings provide links between chronic stressors, inflammation, and mood disorders. Furthermore, traumatic or chronic exposure to psychological stressors may promote stress sensitization, in which individuals have long-term complications, including increased vulnerability to subsequent stressors. Post-traumatic stress disorder (PTSD) is a clinically relevant example of stress sensitization. PTSD alters neuronal circuitry and mood; however, the mechanisms underlying long-term stress sensitization within this disorder are unclear. Rodent models of chronic social defeat recapitulate several key physiological, immunological, and behavioral responses associated with psychological stress in humans. Repeated social defeat (RSD) uniquely promotes the convergence of neuronal, central inflammatory (microglial), and peripheral immune (monocyte) pathways, leading to prolonged anxiety, social withdrawal, and cognitive impairment. Moreover, RSD promotes stress sensitization, in which mice are highly sensitive to subthreshold stress exposure and recurrence of anxiety weeks after the cessation of stress. Therefore, the purpose of this Review is to discuss the influence of social-defeat stress on the immune system that may underlie stress sensitization within three key cellular compartments: neurons, microglia, and monocytes. Delineating the mechanisms of stress sensitization is critical in understanding and treating conditions such as PTSD.

Inflammatory Glycoprotein YKL-40 Is Elevated after Coronary Artery Bypass Surgery and Correlates with Leukocyte Chemotaxis and Myocardial Injury, a Pilot Study

The aim of the present study was to investigate the levels of YKL-40 during and after coronary artery bypass grafting surgery (CABG) and to establish possible connections between YKL-40 and markers of oxidative stress, inflammation, and myocardial injury. Patients undergoing elective CABG utilizing cardiopulmonary bypass (CPB) were recruited into the study. Blood samples were collected at the onset of anesthesia, during surgery and post-operatively. Levels of YKL-40, 8-isoprostane, interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1) and troponin T (TnT) were measured by immunoassay. YKL-40 levels increased significantly 24 h after CPB. Positive correlation was seen between post-operative TnT and YKL-40 levels (r = 0.457, p = 0.016) and, interestingly, baseline YKL-40 predicted post-operative TnT increase (r = 0.374, p = 0.050). There was also a clear association between YKL-40 and the chemotactic factors MCP-1 (r = 0.440, p = 0.028) and IL-8 (r = 0.484, p = 0.011) linking YKL-40 to cardiac inflammation and fibrosis following CABG. The present results show, for the first time, that YKL-40 is associated with myocardial injury and leukocyte-activating factors following coronary artery bypass surgery. YKL-40 may be a factor and/or biomarker of myocardial inflammation and injury and subsequent fibrosis following heart surgery.