Macrophage activation by endogenous danger signals

Impact of new cyclooxygenase 2 inhibitors on human cytomegalovirus replication in vitro

BACKGROUND

Human cytomegalovirus (HCMV) is involved in complications on immunocompromised patients. Current therapeutics are associated with several drawbacks, such as nephrotoxicity.

PURPOSE

As HCMV infection affects inflammation pathways, especially prostaglandin E2 (PGE2) production via cyclooxygenase 2 enzyme (COX-2), we designed 2'-hydroxychalcone compounds to inhibit human cytomegalovirus.

STUDY DESIGN

We first selected the most efficient new synthetic chalcones for their effect against COX-2-catalyzed PGE2.

STUDY SAMPLE

Among the selected compounds, we assessed the antiviral efficacy against different HCMV strains, such as the laboratory strain AD169 and clinical strains (naïve or multi-resistant to conventional drugs) and toxicity on human cells.

RESULTS

The most efficient and less toxic compound (chalcone 7) was tested against HCMV in combination with other antiviral molecules: artesunate (ART), baicalein (BAI), maribavir (MBV), ganciclovir (GCV), and quercetin (QUER) using Compusyn software. Association of chalcone 7 with MBV and BAI is synergistic, antagonistic with QUER, and additive with GCV and ART.

CONCLUSION

These results provide a promising search path for potential bitherapies against HCMV.

Macrophages in heterotopic ossification: from mechanisms to therapy

Heterotopic ossification (HO) is the formation of extraskeletal bone in non-osseous tissues. It is caused by an injury that stimulates abnormal tissue healing and regeneration, and inflammation is involved in this process. It is worth noting that macrophages are crucial mediators of inflammation. In this regard, abundant macrophages are recruited to the HO site and contribute to HO progression. Macrophages can acquire different functional phenotypes and promote mesenchymal stem cell (MSC) osteogenic differentiation, chondrogenic differentiation, and angiogenesis by expressing cytokines and other factors such as the transforming growth factor-β1 (TGF-β1), bone morphogenetic protein (BMP), activin A (Act A), oncostatin M (OSM), substance P (SP), neurotrophin-3 (NT-3), and vascular endothelial growth factor (VEGF). In addition, macrophages significantly contribute to the hypoxic microenvironment, which primarily drives HO progression. Thus, these have led to an interest in the role of macrophages in HO by exploring whether HO is a "butterfly effect" event. Heterogeneous macrophages are regarded as the "butterflies" that drive a sequence of events and ultimately promote HO. In this review, we discuss how the recruitment of macrophages contributes to HO progression. In particular, we review the molecular mechanisms through which macrophages participate in MSC osteogenic differentiation, angiogenesis, and the hypoxic microenvironment. Understanding the diverse role of macrophages may unveil potential targets for the prevention and treatment of HO.

Isolation of Skin Leukocytes Uncovers Phagocyte Inflammatory Responses During Induction and Resolution of Cutaneous Inflammation in Fish

Leukocytes offer a critical layer of protection to the host following skin infections. Delineating the kinetics of cutaneous leukocyte recruitment as well as their anti-microbial and regulatory profiles is challenging since it requires the isolation of adequate cell numbers and maintenance of their functional properties. Herein, we took advantage of a modified procedure to gain insights into the contributions of fish phagocytes through induction and resolution phases of acute cutaneous inflammation in goldfish (Carassius auratus). Our data shows early upregulation of pro-inflammatory cytokines and chemokines, which was paired with neutrophil-dominant leukocyte migration of neutrophils from circulation to the injury site. Recruited neutrophils were associated with high levels of reactive oxygen species (ROS). Following pathogen elimination, a reduction in ROS levels and pro-inflammatory cytokines expression preceded the resolution of inflammation. These results provide a better understanding of the cutaneous immune responses in fish. Moreover, the increased viability and functionality of isolated skin leukocytes opens the door to better understand a range of additional skin diseases.

Macrophage reprogramming into a pro-healing phenotype by siRNA delivered with LBL assembled nanocomplexes for wound healing applications

Excessive inflammatory responses in wounds are characterized by the presence of high levels of pro-inflammatory M1 macrophages rather than pro-healing M2 macrophages, which leads to delayed wound healing. Macrophage reprogramming from the M1 to M2 phenotype through knockdown of interferon regulatory factor 5 (irf5) has emerged as a possible therapeutic strategy. While downregulation of irf5 could be achieved by siRNA, it very much depends on successful intracellular delivery by suitable siRNA carriers. Here, we report on highly stable selenium-based layer-by-layer (LBL) nanocomplexes (NCs) for siRNA delivery with polyethyleneimine (PEI-LBL-NCs) as the final polymer layer. PEI-LBL-NCs showed good protection of siRNA with only 40% siRNA release in a buffer of pH = 8.5 after 72 h or in simulated wound fluid after 4 h. PEI-LBL-NCs also proved to be able to transfect RAW 264.7 cells with irf5-siRNA, resulting in successful reprogramming to the M2 phenotype as evidenced by a 3.4 and 2.6 times decrease in NOS-2 and TNF-α mRNA expression levels, respectively. Moreover, irf5-siRNA transfected cells exhibited a 2.5 times increase of the healing mediator Arg-1 and a 64% increase in expression of the M2 cell surface marker CD206⁺. Incubation of fibroblast cells with conditioned medium isolated from irf5-siRNA transfected RAW 264.7 cells resulted in accelerated wound healing in an in vitro scratch assay. These results show that irf5-siRNA loaded PEI-LBL-NCs are a promising therapeutic approach to tune macrophage polarization for improved wound healing.

The Expression Levels of Toll-like Receptors after Metallic Particle and Ion Exposition in the Synovium of a Murine Model

To date, the exact role of specific Toll-like receptors (TLRs) in regulating immune reactivity to metallic byproducts of orthopedic implants has not been fully clarified. In light of the situation, our objective in this investigation was to assess the expression levels of surface TLRs after metallic particle and ion exposure in an established animal model. Ten female BALB/c mice in each group received intra-articular injections of phosphate buffer (PBS) (control), metallic particles (MP), and metallic ions (MI), respectively. Seven days later, immunohistochemical staining was undertaken in the synovial layer of the murine knee joints using anti-TLR 1, 2, 4, 5, and 6 polyclonal antibodies. In addition to increased cellular infiltrates and a hyperplastic synovial membrane, the MP group showed significantly elevated TLR expression compared to the control group and had higher TLR 1-, 4-, and 6-positive cells than the MI group (p < 0.0167). TLR 4- and TLR 6-positive cells were significantly augmented for the MI group compared to the control group (p < 0.0167). Additionally, greenish corrosion particles found in the necrotic tissue suggested that metallic particles might release a certain level of locally toxic metallic ions in vivo.

Diagnosis and management of cardiac allograft vasculopathy

One of the main causes of death beyond the first year after heart transplantation is cardiac allograft vasculopathy (CAV). This review summarises the current understanding of its complex pathophysiology, detection and treatment, including the available data on non-invasive imaging modalities used for screening and diagnosis. A better understanding of this entity is crucial to improving the long-term outcomes of the growing population of patients with a heart transplant.

Bioactive compounds from Physalis angulata and their anti-inflammatory and cytotoxic activities

A new compound, physalucoside A (1), together with seven withanolides (2-8) and three flavonoids (9-11), were isolated from Physalis angulata L. (Solanaceae), a medicinal plant native to Vietnam. The chemical structures of these compounds were elucidated by one- and two-dimensional NMR spectra, high-resolution electrospray ionization mass spectrometry analyses, and chemical reactivity. The anti-inflammatory and cytotoxic activities of isolated compounds were also evaluated. These data suggest that the anti-inflammatory activity of P. angulata is due primarily to its withanolide content. This study demonstrates the potential of withanolides as promising candidates for the development of new anti-inflammatory drugs.

Multiple versus solitary giant cell lesions of the jaw: Similar or distinct entities?

The majority of giant cell lesions of the jaw present as a solitary focus of disease in bones of the maxillofacial skeleton. Less frequently they occur as multifocal lesions. This raises the clinical dilemma if these should be considered distinct entities and therefore each need a specific therapeutic approach. Solitary giant cell lesions of the jaw present with a great diversity of symptoms. Recent molecular analysis revealed that these are associated with somatic gain-of-function mutations in KRAS, FGFR1 or TRPV4 in a large component of the mononuclear stromal cells which all act on the RAS/MAPK pathway. For multifocal lesions, a small group of neoplastic multifocal giant cell lesions of the jaw remain after ruling out hyperparathyroidism. Strikingly, most of these patients are diagnosed with jaw lesions before the age of 20 years, thus before the completion of dental and jaw development. These multifocal lesions are often accompanied by a diagnosis or strong clinical suspicion of a syndrome. Many of the frequently reported syndromes belong to the so-called RASopathies, with germline or mosaic mutations leading to downstream upregulation of the RAS/MAPK pathway. The other frequently reported syndrome is cherubism, with gain-of-function mutations in the SH3BP2 gene leading through assumed and unknown signaling to an autoinflammatory bone disorder with hyperactive osteoclasts and defective osteoblastogenesis. Based on this extensive literature review, a RAS/MAPK pathway activation is hypothesized in all giant cell lesions of the jaw. The different interaction between and contribution of deregulated signaling in individual cell lineages and crosstalk with other pathways among the different germline- and non-germline-based alterations causing giant cell lesions of the jaw can be explanatory for the characteristic clinical features. As such, this might also aid in the understanding of the age-dependent symptomatology of syndrome associated giant cell lesions of the jaw; hopefully guiding ideal timing when installing treatment strategies in the future.

Cell-Inspired Biomaterials for Modulating Inflammation

Inflammation is a crucial part of wound healing and pathogen clearance. However, it can also play a role in exacerbating chronic diseases and cancer progression when not regulated properly. A subset of current innate immune engineering research is focused on how molecules such as lipids, proteins, and nucleic acids native to a healthy inflammatory response can be harnessed in the context of biomaterial design to promote healing, decrease disease severity, and prolong survival. The engineered biomaterials in this review inhibit inflammation by releasing anti-inflammatory cytokines, sequestering proinflammatory cytokines, and promoting phenotype switching of macrophages in chronic inflammatory disease models. Conversely, other biomaterials discussed here promote inflammation by mimicking pathogen invasion to inhibit tumor growth in cancer models. The form that these biomaterials take spans a spectrum from nanoparticles to large-scale hydrogels to surface coatings on medical devices. Cell-inspired molecules have been incorporated in a variety of creative ways, including loaded into or onto the surface of biomaterials or used as the biomaterials themselves.

Revisiting the Mechanisms of Immune Evasion Employed by Human Parasites

For the establishment of a successful infection, i.e., long-term parasitism and a complete life cycle, parasites use various diverse mechanisms and factors, which they may be inherently bestowed with, or may acquire from the natural vector biting the host at the infection prelude, or may take over from the infecting host, to outmaneuver, evade, overcome, and/or suppress the host immunity, both innately and adaptively. This narrative review summarizes the up-to-date strategies exploited by a number of representative human parasites (protozoa and helminths) to counteract the target host immune defense. The revisited information should be useful for designing diagnostics and therapeutics as well as vaccines against the respective parasitic infections.

Two-Photon, Ratiometric, Quantitative Fluorescent Probe Reveals Fluctuation of Peroxynitrite Regulated by Arginase 1

Peroxynitrite, a transient reactive oxygen species (ROS), is believed to play a deleterious role in physiological processes. Herein, we report a two-photon ratiometric fluorescent probe that selectively reacts with peroxynitrite yielding a >200-fold change upon reaction. The probe effectively visualized fluctuations in peroxynitrite generation by arginase 1 in vivo and in vitro. This provides evidence that arginase 1 is a critical regulator of peroxynitrite.

Macrophage Responses to Environmental Stimuli During Homeostasis and Disease

Work over the last 40 years has described macrophages as a heterogeneous population that serve as the frontline surveyors of tissue immunity. As a class, macrophages are found in almost every tissue in the body and as distinct populations within discrete microenvironments in any given tissue. During homeostasis, macrophages protect these tissues by clearing invading foreign bodies and/or mounting immune responses. In addition to varying identities regulated by transcriptional programs shaped by their respective environments, macrophage metabolism serves as an additional regulator to temper responses to extracellular stimuli. The area of research known as "immunometabolism" has been established within the last decade, owing to an increase in studies focusing on the crosstalk between altered metabolism and the regulation of cellular immune processes. From this research, macrophages have emerged as a prime focus of immunometabolic studies, although macrophage metabolism and their immune responses have been studied for centuries. During disease, the metabolic profile of the tissue and/or systemic regulators, such as endocrine factors, become increasingly dysregulated. Owing to these changes, macrophage responses can become skewed to promote further pathophysiologic changes. For instance, during diabetes, obesity, and atherosclerosis, macrophages favor a proinflammatory phenotype; whereas in the tumor microenvironment, macrophages elicit an anti-inflammatory response to enhance tumor growth. Herein we have described how macrophages respond to extracellular cues including inflammatory stimuli, nutrient availability, and endocrine factors that occur during and further promote disease progression.

The interplay of DAMPs, TLR4, and proinflammatory cytokines in pulmonary fibrosis

Pulmonary fibrosis is a chronic debilitating condition characterized by progressive deposition of connective tissue, leading to a steady restriction of lung elasticity, a decline in lung function, and a median survival of 4.5 years. The leading causes of pulmonary fibrosis are inhalation of foreign particles (such as silicosis and pneumoconiosis), infections (such as post COVID-19), autoimmune diseases (such as systemic autoimmune diseases of the connective tissue), and idiopathic pulmonary fibrosis. The therapeutics currently available for pulmonary fibrosis only modestly slow the progression of the disease. This review is centered on the interplay of damage-associated molecular pattern (DAMP) molecules, Toll-like receptor 4 (TLR4), and inflammatory cytokines (such as TNF-α, IL-1β, and IL-17) as they contribute to the pathogenesis of pulmonary fibrosis, and the possible avenues to develop effective therapeutics that disrupt this interplay.

Zebrafish Models for the Safety and Therapeutic Testing of Nanoparticles with a Focus on Macrophages

New nanoparticles and biomaterials are increasingly being used in biomedical research for drug delivery, diagnostic applications, or vaccines, and they are also present in numerous commercial products, in the environment and workplaces. Thus, the evaluation of the safety and possible therapeutic application of these nanomaterials has become of foremost importance for the proper progress of nanotechnology. Due to economical and ethical issues, in vitro and in vivo methods are encouraged for the testing of new compounds and/or nanoparticles, however in vivo models are still needed. In this scenario, zebrafish (Danio rerio) has demonstrated potential for toxicological and pharmacological screenings. Zebrafish presents an innate immune system, from early developmental stages, with conserved macrophage phenotypes and functions with respect to humans. This fact, combined with the transparency of zebrafish, the availability of models with fluorescently labelled macrophages, as well as a broad variety of disease models offers great possibilities for the testing of new nanoparticles. Thus, with a particular focus on macrophage-nanoparticle interaction in vivo, here, we review the studies using zebrafish for toxicological and biodistribution testing of nanoparticles, and also the possibilities for their preclinical evaluation in various diseases, including cancer and autoimmune, neuroinflammatory, and infectious diseases.

Identification of a potent ionizable lipid for efficient macrophage transfection and systemic anti-interleukin-1β siRNA delivery against acute liver failure

RNA interference (RNAi) therapy has great potential for treating inflammatory diseases. However, the development of potent carrier materials for delivering siRNA to macrophages is challenging. Herein, we design a set of ionizable lipid nanoparticles (LNPs) to screen and identify a potent carrier of siRNA for silencing an essential pro-inflammatory cytokine, interleukin-1β (IL-1β) in macrophages. The top performance LNP (114-LNP), containing ionizable lipid with spermine as an amine-head group, facilitated efficient siRNA internalization via multiple endocytosis pathways and achieved effective endosome escape in macrophages. The optimized LNP/siIL-1β achieved strong silencing of IL-1β in both activated Raw 264.7 cells and primary macrophages. Furthermore, systematic administration of 114-LNP/siIL-1β complexes could effectively inhibit IL-1β expression in an acute liver failure model and significantly attenuated hepatic inflammation and liver damage. These results suggest that the optimized ionizable lipid nanoparticle represents a promising platform for anti-inflammation therapies.

S100A9 Derived From Myeloma Associated Myeloid Cells Promotes TNFSF13B/TNFRSF13B-Dependent Proliferation and Survival of Myeloma Cells

Multiple myeloma (MM) is a lethal hematological malignancy characterized by abundant myeloid cells in the microenvironment that fuel tumor progression. But the mechanism by which myeloid cells support myeloma cells has not been fully explored. We aimed to examine their effect on bone marrow cells of MM patients by scRNA-seq transcriptome analysis and reveal a high-resolution gene profile of myeloma cells and myeloma-associated myeloid cells. Based on correlation analysis of integrated scRNA-seq and bulk RNA-seq datasets from patients, we confirmed that myeloid-derived S100A9 was involved in TNFSF13B-dependent myeloma cell proliferation and survival. In the animal experiments, S100A9 was found to be critical for MM cell proliferation and survival via TNFSF13B production by myeloid cells, neutrophils, and macrophages. In-vitro analysis of patient primary myeloma cells further demonstrated that enhanced TNFSF13B signaling triggered the canonical NF-κB pathway to boost tumor cell proliferation. All these results suggest that myeloid-derived S100A9 is required for TNFSF13B/TNFRSF13B-dependent cell-fate specification, which provides fresh insights into MM progression.

Lactobacillus acidophilus KLDS 1.0738 inhibits TLR4/NF-κB inflammatory pathway in β-lactoglobulin-induced macrophages via modulating miR-146a

Our previous study has confirmed that Lactobacillus acidophilus KLDS 1.0738 (La KLDS 1.0738) could alleviate β-lactoglobulin (β-Lg)-induced allergic inflammation. This study further explored its molecular regulation mechanism through an in vitro macrophage model. β-Lg-induced macrophages were treated with strains of viable or non-viable L. acidophilus and Toll-like receptor 4 (TLR4) inhibitor or miR-146a inhibitor. Our results revealed that β-Lg stimulation led to the increased expression of TLR4/NF-κB signal pathway in macrophages. Similar to TLR4 inhibitor treatment, La KLDS 1.0738 interventions significantly reduced the allergic inflammation by inhibition of TLR4 pathway, which was superior to the commercial L. acidophilus GMNL-185 strains (La GMNL-185) or the control, especially in living L. acidophilus-treated group. Furthermore, La KLDS 1.0738 strains could remarkably reduce transduction of TLR4 and inflammatory cytokine production, which was closely associated with up-regulation of miR-146a levels. MiR-146a inhibitor attenuated the alleviative effect of La KLDS 1.0738, indicating miR-146a might be a crucial mediator of L. acidophilus strains to reduce β-Lg-induced inflammation in macrophages through TLR4 pathway. In conclusion, these observations highlighted that probiotics might regulate host miRNA levels to down-regulate TLR4/NF-κB-dependent inflammation. PRACTICAL APPLICATIONS: Cow's milk allergy (CMA) is one of the most common diseases of food allergy, which has a high prevalence in infants and young children. La KLDS 1.0738 has been shown to be effective in alleviating β-Lg-induced allergic inflammation. Our study further found that treatment with La KLDS 1.0738 could suppress the TLR4/NF-κB signaling pathway via modulating miR-146a expression, thereby reducing the overexpression of downstream inflammatory factors. This study not only elucidates the specific pathway of La KLDS 1.0738 to relieve allergic inflammation, but also provides a new insight into the molecular mechanism for the remission and treatment of CMA by probiotics.

Capturing Cytokines with Advanced Materials: A Potential Strategy to Tackle COVID-19 Cytokine Storm

The COVID-19 pandemic, induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused great impact on the global economy and people's daily life. In the clinic, most patients with COVID-19 show none or mild symptoms, while approximately 20% of them develop severe pneumonia, multiple organ failure, or septic shock due to infection-induced cytokine release syndrome (the so-called "cytokine storm"). Neutralizing antibodies targeting inflammatory cytokines may potentially curb immunopathology caused by COVID-19; however, the complexity of cytokine interactions and the multiplicity of cytokine targets make attenuating the cytokine storm challenging. Nonspecific in vivo biodistribution and dose-limiting side effects further limit the broad application of those free antibodies. Recent advances in biomaterials and nanotechnology have offered many promising opportunities for infectious and inflammatory diseases. Here, potential mechanisms of COVID-19 cytokine storm are first discussed, and relevant therapeutic strategies and ongoing clinical trials are then reviewed. Furthermore, recent research involving emerging biomaterials for improving antibody-based and broad-spectrum cytokine neutralization is summarized. It is anticipated that this work will provide insights on the development of novel therapeutics toward efficacious management of COVID-19 cytokine storm and other inflammatory diseases.

Applications of biomaterials for immunosuppression in tissue repair and regeneration

The immune system plays an essential role in tissue repair and regeneration. Regardless of innate or adaptive immune responses, immunosuppressive strategies such as macrophage polarization and regulatory T (Treg) cell induction can be used to modulate the immune system to promote tissue repair and regeneration. Biomaterials can improve the production of anti-inflammatory macrophages and Treg cells by providing physiochemical cues or delivering therapeutics such as cytokines, small molecules, microRNA, growth factors, or stem cells in the damaged tissues. Herein, we present an overview of immunosuppressive modulation by biomaterials in tissue regeneration and highlight the mechanisms of macrophage polarization and Treg cell induction. Overall, we foresee that future biomaterials for regenerative strategies will entail more interactions between biomaterials and the immune cells, and more mechanisms of immunosuppression related to T cell subsets remain to be discovered and applied to develop novel biomaterials for tissue repair and regeneration. STATEMENT OF SIGNIFICANCE: Immunosuppression plays a key role in tissue repair and regeneration, and biomaterials can interact with the immune system through their biological properties and by providing physiochemical cues. Here, we summarize the studies on biomaterials that have been used for immunosuppression to facilitate tissue regeneration. In the first part of this review, we demonstrate the crucial role of macrophage polarization and induction of T regulatory (Treg) cells in immunosuppression. In the second part, distinct approaches used by biomaterials to induce immunosuppression are introduced, which show excellent performance in terms of promoting tissue regeneration.

Macrophages in microgravity: the impact of space on immune cells

The effects of a microgravity environment on the myriad types of immune cells present within the human body have been assessed both by bench-scale simulation and suborbital methods, as well as in true spaceflight. Macrophages have garnered increased research interest in this context in recent years. Their functionality in both immune response and tissue remodeling makes them a unique cell to investigate in regards to gravisensitive effects as well as parameters of interest that could impact astronaut health. Here, we review and summarize the literature investigating the effects of microgravity on macrophages and monocytes regarding the microgravity environment simulation/generation methods, cell sources, experiment durations, and parameters of interest utilized within the field. We discuss reported findings on the impacts of microgravity on macrophage/monocyte structure, adhesion and migration, proliferation, genetic expression, cytokine secretion, and reactive oxygen species production, as well as polarization. Based on this body of data, we make recommendations to the field for careful consideration of experimental design to complement existing reports, as the multitude of disparate study methods previously published can make drawing direct comparisons difficult. However, the breadth of different testing methodologies can also lend itself to attempting to identify the most robust and consistent responses to microgravity across various testing conditions.

Damage-Induced Calcium Signaling and Reactive Oxygen Species Mediate Macrophage Activation in Zebrafish

Immediately after a wound, macrophages are activated and change their phenotypes in reaction to danger signals released from the damaged tissues. The cues that contribute to macrophage activation after wounding in vivo are still poorly understood. Calcium signaling and Reactive Oxygen Species (ROS), mainly hydrogen peroxide, are conserved early wound signals that emanate from the wound and guide neutrophils within tissues up to the wound. However, the role of these signals in the recruitment and the activation of macrophages is elusive. Here we used the transparent zebrafish larva as a tractable vertebrate system to decipher the signaling cascade necessary for macrophage recruitment and activation after the injury of the caudal fin fold. By using transgenic reporter lines to track pro-inflammatory activated macrophages combined with high-resolutive microscopy, we tested the role of Ca²⁺ and ROS signaling in macrophage activation. By inhibiting intracellular Ca²⁺ released from the ER stores, we showed that macrophage recruitment and activation towards pro-inflammatory phenotypes are impaired. By contrast, ROS are only necessary for macrophage activation independently on calcium. Using genetic depletion of neutrophils, we showed that neutrophils are not essential for macrophage recruitment and activation. Finally, we identified Src family kinases, Lyn and Yrk and NF-κB as key regulators of macrophage activation in vivo, with Lyn and ROS presumably acting in the same signaling pathway. This study describes a molecular mechanism by which early wound signals drive macrophage polarization and suggests unique therapeutic targets to control macrophage activity during diseases.

Class IIa Histone Deacetylases Drive Toll-like Receptor-Inducible Glycolysis and Macrophage Inflammatory Responses via Pyruvate Kinase M2

Histone deacetylases (HDACs) drive innate immune cell-mediated inflammation. Here we identify class IIa HDACs as key molecular links between Toll-like receptor (TLR)-inducible aerobic glycolysis and macrophage inflammatory responses. A proteomic screen identified the glycolytic enzyme pyruvate kinase M isoform 2 (Pkm2) as a partner of proinflammatory Hdac7 in murine macrophages. Myeloid-specific Hdac7 overexpression in transgenic mice amplifies lipopolysaccharide (LPS)-inducible lactate and promotes a glycolysis-associated inflammatory signature. Conversely, pharmacological or genetic targeting of Hdac7 and other class IIa HDACs attenuates LPS-inducible glycolysis and accompanying inflammatory responses in macrophages. We show that an Hdac7-Pkm2 complex acts as an immunometabolism signaling hub, whereby Pkm2 deacetylation at lysine 433 licenses its proinflammatory functions. Disrupting this complex suppresses inflammatory responses in vitro and in vivo. Class IIa HDACs are thus pivotal intermediates connecting TLR-inducible glycolysis to inflammation via Pkm2.

Unique histological features of the tail skin of cotton rat (Sigmodon hispidus) related to caudal autotomy

Caudal autotomy in rodents is an evolutionarily acquired phenomenon enabling escape from predators, by discarding the tail skin after traumatic injuries. The histological mechanisms underlying caudal autotomy seem to differ among species. Cotton rats (Sigmodon hispidus), which are important laboratory rodents for human infectious diseases, possess a fragile tail. In this study, we compared the tail histology of cotton rats with that of laboratory rats (Rattus norvegicus), which have no fragility on their tail, to elucidate the process of rodent caudal autotomy. First, the cotton rats developed a false autotomy characterized by loss of the tail sheath with the caudal vertebrae remaining without tail regeneration. Second, we found the fracture plane was continuous from the interscale of the tail epidermis to the dermis, which was lined with an alignment of E-cadherin⁺ cells. Third, we found an obvious cleavage plane between the dermis and subjacent tissues of the cotton-rat tail, where the subcutis was composed of looser, finer, and fragmented collagen fibers compared with those of the rat. Additionally, the cotton-rat tail was easily torn, with minimum bleeding. The median coccygeal artery of the cotton rat had a thick smooth muscle layer, and its lumen was filled with the peeled intima with fibrin coagulation, which might be associated with reduced bleeding following caudal autotomy. Taken together, we reveal the unique histological features of the tail relating to the caudal autotomy process in the cotton rat, and provide novel insights to help clarify the rodent caudal autotomy mechanism.

Summary: The unique histological structures in derimis, subcutis and coccygeal artery of the tail skin are related to the caudal autotomy mechanism in the cotton rat.

RNA editing enzyme APOBEC3A promotes pro-inflammatory M1 macrophage polarization

Pro-inflammatory M1 macrophage polarization is associated with microbicidal and antitumor responses. We recently described APOBEC3A-mediated cytosine-to-uracil (C > U) RNA editing during M1 polarization. However, the functional significance of this editing is unknown. Here we find that APOBEC3A-mediated cellular RNA editing can also be induced by influenza or Maraba virus infections in normal human macrophages, and by interferons in tumor-associated macrophages. Gene knockdown and RNA_Seq analyses show that APOBEC3A mediates C>U RNA editing of 209 exonic/UTR sites in 203 genes during M1 polarization. The highest level of nonsynonymous RNA editing alters a highly-conserved amino acid in THOC5, which encodes a nuclear mRNA export protein implicated in M-CSF-driven macrophage differentiation. Knockdown of APOBEC3A reduces IL6, IL23A and IL12B gene expression, CD86 surface protein expression, and TNF-α, IL-1β and IL-6 cytokine secretion, and increases glycolysis. These results show a key role of APOBEC3A cytidine deaminase in transcriptomic and functional polarization of M1 macrophages.

Role of Tristetraprolin in the Resolution of Inflammation

Simple Summary

Chronic inflammatory diseases account for up to 60% of deaths worldwide and, thus, are considered a great threat for human health by the World Health Organization. Nevertheless, acute inflammatory reactions are an integral part of the host defense against invading pathogens or injuries. To avoid excessive damage due to the persistence of a highly reactive environment, inflammations need to resolve in a coordinate and timely manner, ensuring for the immunological normalization of the affected tissues. Since post-transcriptional regulatory mechanisms are essential for effective resolution, the present review discusses the key role of the RNA-binding and post-transcriptional regulatory protein tristetraprolin in establishing resolution of inflammation.

Abstract

Inflammation is a crucial part of immune responses towards invading pathogens or tissue damage. While inflammatory reactions are aimed at removing the triggering stimulus, it is important that these processes are terminated in a coordinate manner to prevent excessive tissue damage due to the highly reactive inflammatory environment. Initiation of inflammatory responses was proposed to be regulated predominantly at a transcriptional level, whereas post-transcriptional modes of regulation appear to be crucial for resolution of inflammation. The RNA-binding protein tristetraprolin (TTP) interacts with AU-rich elements in the 3′ untranslated region of mRNAs, recruits deadenylase complexes and thereby facilitates degradation of its targets. As TTP regulates the mRNA stability of numerous inflammatory mediators, it was put forward as a crucial post-transcriptional regulator of inflammation. Here, we summarize the current understanding of the function of TTP with a specific focus on its role in adding to resolution of inflammation.

MicroRNA-22 negatively regulates LPS-induced inflammatory responses by targeting HDAC6 in macrophages

Dysregulation of histone deacetylase 6 (HDAC6) can lead to the pathologic states and result in the development of various diseases including cancers and inflammatory diseases. The objective of this study was to elucidate the regulatory role of microRNA-22 (miR-22) in HDAC6-mediated expression of proinflammatory cytokines in lipopolysaccharide (LPS)-stimulated macrophages. LPS stimulation induced HDAC6 expression, but suppressed miR-22 expression in macrophages, suggesting possible correlation between HDAC6 and miR-22. Luciferase reporter assays revealed that 3'UTR of HDAC6 was a bona fide target site of miR-22. Transfection of miR-22 mimic significantly inhibited LPS-induced HDAC6 expression, while miR-22 inhibitor further increased LPS-induced HDAC6 expression. LPS-induced activation of NF-κB and AP-1 was inhibited by miR-22 mimic, but further increased by miR-22 inhibitor. LPS-induced expression of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6 was inhibited by miR-22 mimic, but further increased by miR-22 inhibitor. Taken together, these data provide evidence that miR-22 can downregulate LPS-induced expression of proinflammatory cytokines via suppression of NF-κB and AP-1 axis by targeting HDAC6 in macrophages. [BMB Reports 2020; 53(4): 223-228].

Role of Cardiac Macrophages on Cardiac Inflammation, Fibrosis and Tissue Repair

The immune system plays a pivotal role in the initiation, development and resolution of inflammation following insult or damage to organs. The heart is a vital organ which supplies nutrients and oxygen to all parts of the body. Heart failure (HF) has been conventionally described as a disease associated with cardiac tissue damage caused by systemic inflammation, arrhythmia and conduction defects. Cardiac inflammation and subsequent tissue damage is orchestrated by the infiltration and activation of various immune cells including neutrophils, monocytes, macrophages, eosinophils, mast cells, natural killer cells, and T and B cells into the myocardium. After tissue injury, monocytes and tissue-resident macrophages undergo marked phenotypic and functional changes, and function as key regulators of tissue repair, regeneration and fibrosis. Disturbance in resident macrophage functions such as uncontrolled production of inflammatory cytokines, growth factors and inefficient generation of an anti-inflammatory response or unsuccessful communication between macrophages and epithelial and endothelial cells and fibroblasts can lead to aberrant repair, persistent injury, and HF. Therefore, in this review, we discuss the role of cardiac macrophages on cardiac inflammation, tissue repair, regeneration and fibrosis.

Regulation of Toll-like receptors Expression in Muscle cells by Exercise-induced Stress

Objective

This study investigates the expression patterns of toll-like receptors (TLRs) and intracellular mediators in horse muscle cells after exercise, and the relationship between TLRS expression in stressed horse muscle cells and immune cell migration toward them.

Methods

The expression patterns of the TLRs (TLR2, TLR4, and TLR8) and downstream signaling pathway-related genes (myeloid differentiation primary response 88 [MYD88]; activating transcription factor 3 [ATF3]) are examined in horse tissues, and horse peripheral blood mononuclear cells (PBMCs), polymorphonuclear cells (PMNs) and muscles in response to exercise, using the quantitative reverse transcription-polymerase chain reaction (qPCR). Expressions of chemokine receptor genes, i.e., C-X-C motif chemokine receptor 2 (CXCR2) and C-C motif chemokine receptor 5 (CCR5), are studied in PBMCs and PMNs. A horse muscle cell line is developed by transfecting SV-T antigen into fetal muscle cells, followed by examination of muscle-specific genes. Horse muscle cells are treated with stressors, i.e., cortisol, hydrogen peroxide (H₂O₂), and heat, to mimic stress conditions in vitro, and the expression of TLR4 and TLR8 are examined in stressed muscle cells, in addition to migration activity of PBMCs toward stressed muscle cells.

Results

The qPCR revealed that TLR4 message was expressed in cerebrum, cerebellum, thymus, lung, liver, kidney, and muscle, whereas TLR8 expressed in thymus, lung, and kidney, while TLR2 expressed in thymus, lung, and kidney. Expressions of TLRs, i.e., TLR4 and TLR8, and mediators, i.e., MYD88 and ATF3, were upregulated in muscle, PBMCs and PMNs in response to exercise. Expressions of CXCR2 and CCR5 were also upregulated in PBMCs and PMNs after exercise. In the muscle cell line, TLR4 and TLR8 expressions were upregulated when cells were treated with stressors such as cortisol, H₂O₂, and heat. Migration of PBMCs toward stressed muscle cells was increased by exercise and oxidative stresses, and combinations of these. Treatment with methylsulfonylmethane (MSM), an antioxidant on stressed muscle cells, reduced migration of PBMCs toward stressed muscle cells.

Conclusion

In this study, we have successfully cultured horse skeletal muscle cells, isolated horse PBMCs, and established an in vitro system for studying stress-related gene expressions and function. Expression of TLR4, TLR8, CXCR2, and CCR5 in horse muscle cells was higher in response to stressors such as cortisol, H₂O₂, and heat, or combinations of these. In addition, migration of PBMCs toward muscle cells was increased when muscle cells were under stress, but inhibition of reactive oxygen species by MSM modulated migratory activity of PBMCs to stressed muscle cells. Further study is necessary to investigate the biological function(s) of the TLR gene family in horse muscle cells.

Immunomodulatory Effects of Recombinant Mycobacterium smegmatis Expressing Antigen-85B Epitopes in Infected J774A.1 Murine Macrophages

Tuberculosis (TB) causes more than 1.5 million deaths each year, remaining a significant global health problem. Mycobacterium smegmatis (M. smegmatis) and Mycobacterium tuberculosis (M. tuberculosis) share features, which support the use of the former use in new generation TB vaccine development. In a previous study, the specific humoral and cellular immunogenicity of a recombinant M. smegmatis strain expressing epitopes from M. tuberculosis Ag85B protein (rMs064), was demonstrated in mice. In the current study, the immunomodulatory capacity of rMs064 was determined in a J774A.1 murine macrophage cell line. To determine the immunomodulatory effect of rMs064 in J774A.1 macrophages, the expression of inducible nitric oxide synthase (iNOS) and production of nitric oxide (NO) was evaluated. The expression of activation surface markers (MHC-II, CD40, CD80 and CD86) and the production of cytokines (IL-1β, TNF-α, IL-12p70 and IL-6) was also determined in rMs064 infected J774A.1 macrophages. Our findings showed the ability of rMs064 to induce substantial increases in macrophage activation markers expression; MHC class II and CD40, compared with M. smegmatis transformed with the empty vector (rMs012) and uninfected cells. rMs064 induced significant increases in IL-12p70 compared to uninfected cells. The expression of iNOS and CD86, and the production of IL-1β, and TNF-α were increased in rMs064 and rMs012, compared to uninfected cells. rMs064 demonstrated its immunomodulatory ability by stimulating the innate immune response, which supports its further evaluation as a TB vaccine candidate.

Fibronectin Fragments and Inflammation During Canine Intervertebral Disc Disease

Background: Canine intervertebral disc disease (IVDD) represents a significant clinical problem in veterinary medicine, with similarities to the human pathology. Host-derived damage-associated molecular patterns like fibronectin fragments (FnF) that develop during tissue dysfunction may be of specific relevance to IVD pathologies by inducing an inflammatory response in resident cells. Aim: This project aimed to determine the presence and pathobiological role of FnF during IVD herniation in dogs, with a focus on inflammation. Methods: Herniated nucleus pulposus (NP) material from five dogs as well as non-herniated adjacent NP material from three dogs was collected during spinal surgery required due to acute IVD herniation. The presence of different types of FnF were determined by Western blot analysis. NP cells isolated from six herniated canine IVDs were then exposed to 30 kDa FnF. NP cell inflammation and catabolism was examined by investigating the expression of IL-1β, IL-6, IL-8, and COX-2, as well as MMP-1 and MMP-3 by qPCR (all targets) and ELISA (IL-6, PGE2). Results: Amongst multiple sized FnF (30, 35, 45, and >170kDa), N-terminal fragments at a size of ~30 kDa were most consistently expressed in all five herniated IVDs. Importantly, these fragments were exclusively present in herniated, but not in non-herniated IVDs. Exposure of canine NP cells to 500 nM 30 kDa FnF caused a significant upregulation of IL-6 (62.5 ± 79.9, p = 0.032) and IL-8 (53.0 ± 75.7, p = 0.031) on the gene level, whereas IL-6 protein analysis was inconclusive. Donor-donor variation was observed in response to FnF treatment, whereby this phenomenon was most evident for COX-2, with three donors demonstrating a significant downregulation (0.67 ± 0.03, p = 0.003) and three donors showing upregulation (6.9 ± 5.5, p = 0.21). Co-treatment with Sparstolonin B, a TRL-2/TRL-4 antagonist, showed no statistical difference to FnF treatment alone in all tested target genes. Conclusion: Given the presence of the 30 kDa FnF in canine herniated IVDs and the proinflammatory effect of 30 kDa FnF on NP cells, we concluded that the accumulation of FnF may be involved in the pathogenesis of canine IVDD. These results correspond to the findings in humans with IVDD.

Organ-Specific Effects of Low Dose Radiation Exposure: A Comprehensive Review

Ionizing radiation (IR) is a high-energy radiation whose biological effects depend on the irradiation doses. Low-dose radiation (LDR) is delivered during medical diagnoses or by an exposure to radioactive elements and has been linked to the occurrence of chronic diseases, such as leukemia and cardiovascular diseases. Though epidemiological research is indispensable for predicting and dealing with LDR-induced abnormalities in individuals exposed to LDR, little is known about epidemiological markers of LDR exposure. Moreover, difference in the LDR-induced molecular events in each organ has been an obstacle to a thorough investigation of the LDR effects and a validation of the experimental results in in vivo models. In this review, we summarized the recent reports on LDR-induced risk of organ-specifically arranged the alterations for a comprehensive understanding of the biological effects of LDR. We suggested that LDR basically caused the accumulation of DNA damages, controlled systemic immune systems, induced oxidative damages on peripheral organs, and even benefited the viability in some organs. Furthermore, we concluded that understanding of organ-specific responses and the biological markers involved in the responses is needed to investigate the precise biological effects of LDR.

Paclitaxel alleviates the sepsis-induced acute kidney injury via lnc-MALAT1/miR-370-3p/HMGB1 axis

AIMS

To investigate the effects of paclitaxel on lipopolysaccharide (LPS)-induced acute kidney injury (AKI) and its related mechanisms.

MAIN METHODS

The sepsis-associated AKI was induced by LPS using HK-2 cells. Then the mRNA and protein expression levels of relevant genes in the serum of sepsis patients and HK-2 cells with LPS-induced AKI were detected by qRT-PCR and western blot analyses before and after paclitaxel treatment, respectively. Subsequently, the cell counting kit-8 (CCK-8) and flow cytometry assays were performed to estimate the effects of paclitaxel, lnc-MALAT1, miR-370-3p and HMGB1 on the proliferation and apoptosis of HK-2 cells injured by LPS.

KEY FINDINGS

Lnc-MALAT1 was increased both in the serum of sepsis patients and cells injured by LPS, which could inhibit the cell proliferation, promote the cell apoptosis and increase the expression of TNF-α, IL-6 and IL-1β caused by paclitaxel. Moreover, lnc-MALAT1 was sponged with miR-370-3p which had the inverse effects with lnc-MALAT1 in LPS induced HK-2 cells. What's more, miR-370-3p targeted HMGB1 which was induced in serum and cells of sepsis. Knockdown of miR-370-3p inhibited the expression of HMGB1 and suppressed the proliferation but promoted the apoptosis of HK-2 cells injured by LPS as well as the expression of TNF-α, IL-6 and IL-1β. Besides, paclitaxel restrained the expression of HMGB1 via regulating lnc-MALAT1/miR-370-3p axis.

SIGNIFICANCE

Paclitaxel could protect against LPS-induced AKI via the regulation of lnc-MALAT1/miR-370-3p/HMGB1 axis and the expression of TNF-α, IL-6 and IL-1β, revealing that paclitaxel might act as a therapy drug in reducing sepsis-associated AKI.

Bioactive hyaluronic acid fragments inhibit lipopolysaccharide-induced inflammatory responses via the Toll-like receptor 4 signaling pathway

The high- and the low-molecular weight hyaluronic acids (HMW-HA and LMW-HA, respectively) showed different biological activities in inflammation. However, the role of LMW-HA in inflammatory response is controversial. In this study, we aimed to investigate the effect of bioactive hyaluronan (B-HA) on lipopolysaccharide (LPS)-induced inflammatory responses in human macrophages and mice. B-HA was produced from HA treated with glycosylated recombinant human hyaluronidase PH20. Human THP-1 cells were induced to differentiate into macrophages. THP-1-derived macrophages were treated with B-HA, LPS, or B-HA + LPS. The mRNA expression and the production of inflammatory cytokines were determined using quantitative real-time PCR and enzyme-linked immunosorbent assay. The phosphorylation levels of proteins in the nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and IRF-3 signaling pathways were measured using Western blot. The in vivo efficacy of B-HA was assessed in a mouse model of LPS-induced inflammation. Results showed that B-HA inhibited the expression of TNF-α, IL-6, IL-1, and IFN-β, and enhanced the expression of the antiinflammatory cytokine IL-10 in LPS-induced inflammatory responses in THP-1-derived macrophages and in vivo. B-HA significantly suppressed the phosphorylation of the TLR4 signaling pathway proteins p65, IKKα/β, IκBα, JNK1/2, ERK1/2, p38, and IRF-3. In conclusion, our results demonstrated that the B-HA attenuated the LPS-stimulated inflammatory response by inhibiting the activation of the TLR4 signaling pathway. B-HA could be a potential anti-inflammatory drug in the treatment of inflammatory disease.

Macrophage polarization in intestinal inflammation and gut homeostasis

Gut homeostasis is a process that requires a prudent balance of host responses to the beneficial enteric microbial community and the pathogenic stimuli that can arise. The lack of this balance in the intestine can result in inflammatory bowel diseases, where the immune system dysfunctions leading to exacerbated inflammatory responses. In this process, macrophages are considered to play a pivotal role. In this review, we describe the important role of macrophages in maintaining intestinal homeostasis and we discuss how altered macrophage function may lead to inflammatory bowel diseases. The plasticity of macrophages during the gut inflammatory response shows the broad role of these cells in orchestrating not only the onset of inflammation but also its termination as well as healing and repair. Indeed, the state of macrophage polarization can be the key factor in defining the resolution or the progression of inflammation and disease. Here, we discuss the different populations of macrophages and their implication in development, propagation, control and resolution of inflammatory bowel diseases.

Lung-derived HMGB1 is detrimental for vascular remodeling of metabolically imbalanced arterial macrophages

Pulmonary disease increases the risk of developing abdominal aortic aneurysms (AAA). However, the mechanism underlying the pathological dialogue between the lungs and aorta is undefined. Here, we find that inflicting acute lung injury (ALI) to mice doubles their incidence of AAA and accelerates macrophage-driven proteolytic damage of the aortic wall. ALI-induced HMGB1 leaks and is captured by arterial macrophages thereby altering their mitochondrial metabolism through RIPK3. RIPK3 promotes mitochondrial fission leading to elevated oxidative stress via DRP1. This triggers MMP12 to lyse arterial matrix, thereby stimulating AAA. Administration of recombinant HMGB1 to WT, but not Ripk3^-/- mice, recapitulates ALI-induced proteolytic collapse of arterial architecture. Deletion of RIPK3 in myeloid cells, DRP1 or MMP12 suppression in ALI-inflicted mice repress arterial stress and brake MMP12 release by transmural macrophages thereby maintaining a strengthened arterial framework refractory to AAA. Our results establish an inter-organ circuitry that alerts arterial macrophages to regulate vascular remodeling.

Modeling Cancer Using Zebrafish Xenografts: Drawbacks for Mimicking the Human Microenvironment

The first steps towards establishing xenografts in zebrafish embryos were performed by Lee et al., 2005 and Haldi et al., 2006, paving the way for studying human cancers using this animal species. Since then, the xenograft technique has been improved in different ways, ranging from optimizing the best temperature for xenografted embryo incubation, testing different sites for injection of human tumor cells, and even developing tools to study how the host interacts with the injected cells. Nonetheless, a standard protocol for performing xenografts has not been adopted across laboratories, and further research on the temperature, microenvironment of the tumor or the cell-host interactions inside of the embryo during xenografting is still needed. As a consequence, current non-uniform conditions could be affecting experimental results in terms of cell proliferation, invasion, or metastasis; or even overestimating the effects of some chemotherapeutic drugs on xenografted cells. In this review, we highlight and raise awareness regarding the different aspects of xenografting that need to be improved in order to mimic, in a more efficient way, the human tumor microenvironment, resulting in more robust and accurate in vivo results.

Biological Properties of Yeast-based Mannoprotein for Prospective Biomedical Applications

BACKGROUND

Natural products constitute more than half of all biomolecules lately being used in clinical settings. Mannoprotein derived from the yeast cell wall has found full biotechnological applications.

OBJECTIVE

This study was intended to investigate the antioxidant, anticancer, and toxicological properties of Kluyveromyces marxianus mannoprotein (KM).

METHODS

The KM extract was obtained through a sequence of operations, including centrifugation for cell isolation, precipitation with potassium citrate/sodium metabisulfite, and recovery and purification. Its antioxidant, growth inhibition, macrophage mitogenic, and toxic activities were evaluated for its future use in the biomedical field.

RESULTS

Significant inhibitory effects of KM were obtained on reactive species. It showed antiproliferative activity against HeLa (human cervical adenocarcinoma) and MCF-7 (human breast cancer) cell lines with no toxic effects on HUVECs (human umbilical vein endothelial cells). The in vitro model of CHO-K1 (Chinese hamster ovary) cell lines did not show the cytotoxic and genotoxic of KM. Moreover, it enhanced macrophage activity in terms of nitric oxide (NO) production and viability. No sign of acute toxicity was found in BALB/c mice, and body weight remained unchanged in guinea pigs over three months.

CONCLUSION

Comprehensive biological evaluations in this study are expected to expand the potential of KM as a natural material.

Polymyxin-Induced Cell Death of Human Macrophage-Like THP-1 and Neutrophil-Like HL-60 Cells Associated with the Activation of Apoptotic Pathways

Innate immunity is crucial for the host to defend against infections, and understanding the effect of polymyxins on innate immunity is important for optimizing their clinical use. In this study, we investigated the potential toxicity of polymyxins on human macrophage-like THP-1 and neutrophil-like HL-60 cells. Differentiated THP-1 human macrophages (THP-1-dMs) and HL-60 human neutrophils (HL-60-dNs) were employed. Flow cytometry was used to measure the concentration-dependent effects (100 to 2,500 μM for THP-1-dMs and 5 to 2,500 μM for HL-60-dNs) and time-dependent effects (1,000 μM for THP-1-dMs and 300 μM for HL-60-dNs) of polymyxin B over 24 h. Effects of polymyxin B on mitochondrial activity, activation of caspase-3, caspase-8, and caspase-9, and Fas ligand (FasL) expression in both cell lines were examined using fluorescence imaging, colorimetric, and fluorometric assays. In both cell lines, polymyxin B induced concentration- and time-dependent loss of viability at 24 h with 50% effective concentration (EC₅₀) values of 751.8 μM (95% confidence interval [CI], 692.1 to 816.6 μM; Hill slope, 3.09 to 5.64) for THP-1-dM cells and 175.4 μM (95% CI, 154.8 to 198.7 μM; Hill slope, 1.42 to 2.21) for HL-60-dN cells. A concentration-dependent loss of mitochondrial membrane potential and generation of mitochondrial superoxide was also observed. Polymyxin B-induced apoptosis was associated with concentration-dependent activation of all three tested caspases. The death receptor apoptotic pathway activation was demonstrated by a concentration-dependent increase of FasL expression. For the first time, our results reveal that polymyxin B induced concentration- and time-dependent cell death in human macrophage-like THP-1 and neutrophil-like HL-60 cells associated with mitochondrial and death receptor apoptotic pathways.

Inter-individual differences in immune profiles of outbred rats screened for an emotional reactivity phenotype

Inter-individual differences in emotional reactivity predict susceptibility versus resilience to mood pathology. Using experimentally-naïve outbred rats that vary in locomotor reactivity to the mild stress of an inescapable novel environment [i.e., top and bottom 1/3rd of the population identified as high responders (HR) and low responders (LR) respectively], we determined baseline variations in immune functions. Innate and adaptive immune responses vary basally in LRHR rats, namely a shift towards TH1 in LRs and TH2 in HRs was observed. These inter-individual variations in immune profiles in LRHRs could have significant implications in mood alterations and immune reactivity to microbes and cancer.

Nanomedicine therapies modulating Macrophage Dysfunction: a potential strategy to attenuate Cytokine Storms in severe infections

Cytokine storms, defined by the dysregulated and excessive production of multiple pro-inflammatory cytokines, are closely associated with the pathology and mortality of several infectious diseases, including coronavirus disease 2019 (COVID-19). Effective therapies are urgently needed to block the development of cytokine storms to improve patient outcomes, but approaches that target individual cytokines may have limited effect due to the number of cytokines involved in this process. Dysfunctional macrophages appear to play an essential role in cytokine storm development, and therapeutic interventions that target these cells may be a more feasible approach than targeting specific cytokines. Nanomedicine-based therapeutics that target macrophages have recently been shown to reduce cytokine production in animal models of diseases that are associated with excessive proinflammatory responses. In this mini-review, we summarize important studies and discuss how macrophage-targeted nanomedicines can be employed to attenuate cytokine storms and their associated pathological effects to improve outcomes in patients with severe infections or other conditions associated with excessive pro-inflammatory responses. We also discuss engineering approaches that can improve nanocarriers targeting efficiency to macrophages, and key issues should be considered before initiating such studies.

Cold-inducible RNA-binding protein might determine the severity and the presences of major/minor criteria for severe community-acquired pneumonia and best predicted mortality

Background

Severity of community-acquired pneumonia (CAP) depends on microbial pathogenicity, load and virulence, and immune responses. The Infectious Disease Society of America and the American Thoracic Society (IDSA/ATS) minor criteria responsible for clinical triage of patients with CAP are of unequal weight in predicting mortality. It is unclear whether the IDSA/ATS major/minor criteria might be strongly and positively associated with the immune responses. It is warranted to explore this intriguing hypothesis.

Methods

A prospective cohort study of 404 CAP patients was performed. Cold-inducible RNA-binding protein (CIRP) levels were measured using a sandwich-based enzyme-linked immunosorbent assay. The receiver operating characteristic curves were created and the areas under the curves were calculated to illustrate and compare the accuracy of the indices.

Results

Severe CAP patients meeting the major criteria had the highest plasma concentrations of CIRP. The more the number of most predictive minor criteria strongly associated to mortality, i.e. arterial oxygen pressure/fraction inspired oxygen ≤ 250 mmHg, confusion, and uremia, present, the higher the CIRP level. Interestingly, the patients with non-severe CAP meeting the most predictive minor criteria demonstrated unexpectedly higher CIRP level compared with the patients with severe CAP not fulfilling the criteria. Procalcitonin (PCT), interleukin-6 (IL-6), C-reactive protein (CRP), sequential organ failure assessment (SOFA) and pneumonia severity index (PSI) scores, and mortality confirmed similar intriguing patterns. CIRP was strongly linked to PCT, IL-6, CRP, minor criteria, SOFA and PSI scores, and mortality (increased odds ratio 3.433). The pattern of sensitivity, specificity, positive predictive value, and Youden’s index of CIRP ≥ 3.50 ng/mL for predicting mortality was the optimal. The area under the receiver operating characteristic curve of CIRP was the highest among the indices.

Conclusions

CIRP levels were strongly correlated with the IDSA/ATS major/minor criteria. CIRP might determine the severity and the presences of major/minor criteria and best predicted mortality, and a CIRP of ≥ 3.50 ng/mL might be more valuable cut-off value for severe CAP, suggesting that CIRP might be a novel and intriguing biomarker for pneumonia to monitor host response and predict mortality, which might have implications for more accurate clinical triage decisions.

Profiling the Course of Resolving vs. Persistent Inflammation in Human Monocytes: The Role of IL-1 Family Molecules

Monocytes and macrophages have a central role in all phases of an inflammatory reaction. To understanding the regulation of monocyte activation during a physiological or pathological inflammation, we propose two in vitro models that recapitulate the different phases of the reaction (recruitment, initiation, development, and resolution vs. persistence of inflammation), based on human primary blood monocytes exposed to sequential modifications of microenvironmental conditions. These models exclusively describe the functional development of blood-derived monocytes that first enter an inflammatory site. All reaction phases were profiled by RNA-Seq, and the two models were validated by studying the modulation of IL-1 family members. Genes were differentially modulated, and distinct clusters were identified during the various phases of inflammation. Pathway analysis revealed that both models were enriched in pathways involved in innate immune activation. We observe that monocytes acquire an M1-like profile during early inflammation, and switch to a deactivated M2-like profile during both the resolving and persistent phases. However, during persistent inflammation they partially maintain an M1 profile, although they lose the ability to produce inflammatory cytokines compared to M1 cells. The production of IL-1 family molecules by ELISA reflected the transcriptomic profiles in the distinct phases of the two inflammatory reactions. Based on the results, we hypothesize that persistence of inflammatory stimuli cannot maintain the M1 activated phenotype of incoming monocytes for long, suggesting that the persistent presence of M1 cells and effects in a chronically inflamed tissue is mainly due to activation of newly incoming cells. Moreover, being IL-1 family molecules mainly expressed and secreted by monocytes during the early stages of the inflammatory response (within 4-14 h), and the rate of their production decreasing during the late phase of both resolving and persistent inflammation, we suppose that IL-1 factors are key regulators of the acute defensive innate inflammatory reaction that precedes establishment of longer-term adaptive immunity, and are mainly related to the presence of recently recruited blood monocytes. The well-described role of IL-1 family cytokines and receptors in chronic inflammation is therefore most likely dependent on the continuous influx of blood monocytes into a chronically inflamed site.

The liver fibrosis niche: Novel insights into the interplay between fibrosis-composing mesenchymal cells, immune cells, endothelial cells, and extracellular matrix

Liver fibrosis is a hepatic wound-healing response caused by chronic liver diseases that include viral hepatitis, alcoholic liver disease, non-alcoholic steatohepatitis, and cholestatic liver disease. Liver fibrosis eventually progresses to cirrhosis that is histologically characterized by an abnormal liver architecture that includes distortion of liver parenchyma, formation of regenerative nodules, and a massive accumulation of extracellular matrix (ECM). Despite intensive investigations into the underlying mechanisms of liver fibrosis, developments of anti-fibrotic therapies for liver fibrosis are still unsatisfactory. Recent novel experimental approaches, such as single-cell RNA sequencing and proteomics, have revealed the heterogeneity of ECM-producing cells (mesenchymal cells) and ECM-regulating cells (immune cells and endothelial cells). These approaches have accelerated the identification of fibrosis-specific subpopulations among these cell types. The ECM also consists of heterogenous components. Their production, degradation, deposition, and remodeling are dynamically regulated in liver fibrosis, further affecting the functions of cells responsible for fibrosis. These cellular and ECM elements cooperatively form a unique microenvironment: a fibrotic niche. Understanding the complex interplay between these elements could lead to a better understanding of underlying fibrosis mechanisms and to the development of effective therapies.

Counter Regulation of Spic by NF-κB and STAT Signaling Controls Inflammation and Iron Metabolism in Macrophages

Activated macrophages must carefully calibrate their inflammatory responses to balance efficient pathogen control with inflammation-mediated tissue damage, but the molecular underpinnings of this "balancing act" remain unclear. Using genetically engineered mouse models and primary macrophage cultures, we show that Toll-like receptor (TLR) signaling induces the expression of the transcription factor Spic selectively in patrolling monocytes and tissue macrophages by a nuclear factor κB (NF-κB)-dependent mechanism. Functionally, Spic downregulates pro-inflammatory cytokines and promotes iron efflux by regulating ferroportin expression in activated macrophages. Notably, interferon-gamma blocks Spic expression in a STAT1-dependent manner. High levels of interferon-gamma are indicative of ongoing infection, and in its absence, activated macrophages appear to engage a "default" Spic-dependent anti-inflammatory pathway. We also provide evidence for the engagement of this pathway in sterile inflammation. Taken together, our findings uncover a pathway wherein counter-regulation of Spic by NF-κB and STATs attune inflammatory responses and iron metabolism in macrophages.

Macrophage Dysregulation and Impaired Skin Wound Healing in Diabetes

Monocytes (Mo) and macrophages (Mϕ) play important roles in normal skin wound healing, and dysregulation of wound Mo/Mϕ leads to impaired wound healing in diabetes. Although skin wound Mϕ originate both from tissue resident Mϕ and infiltrating bone marrow-derived Mo, the latter play dominant roles during the inflammatory phase of wound repair. Increased production of bone marrow Mo caused by alterations of hematopoietic stem and progenitor cell (HSPC) niche and epigenetic modifications of HSPCs likely contributes to the enhanced number of wound Mϕ in diabetes. In addition, an impaired transition of diabetic wound Mϕ from “pro-inflammatory” to “pro-healing” phenotypes driven by the local wound environment as well as intrinsic changes in bone marrow Mo is also thought to be partly responsible for impaired diabetic wound healing. The current brief review describes the origin, heterogeneity and function of wound Mϕ during normal skin wound healing followed by discussion of how dysregulated wound Mϕ numbers and phenotype are associated with impaired diabetic wound healing. The review also highlights the possible links between altered bone marrow myelopoiesis and increased Mo production as well as extrinsic and intrinsic factors that drive wound macrophage dysregulation leading to impaired wound healing in diabetes.

Carboxyamidotriazole exerts anti-inflammatory activity in lipopolysaccharide-induced RAW264.7 macrophages by inhibiting NF-κB and MAPKs pathways

Carboxyamidotriazole (CAI), originally developed as a non-cytotoxic anti-cancer drug, was shown to have anti-inflammatory activity according to recent studies in a number of animal models of inflammation. However, its mechanism of action has not been characterized. Therefore, the present study was performed to identify the anti-inflammatory action of CAI in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages and to identify the signal transduction pathways involved. The in vitro results revealed that CAI had no direct effect on the activity of cyclooxygenase (COX), suggesting a different anti-inflammatory mechanism compared with that of COX-inhibiting non-steroidal anti-inflammatory drugs. Further investigation in RAW264.7 macrophages revealed that CAI decreased the production of nitric oxide via decreasing the LPS-stimulated expression of inducible nitric oxide synthase, and downregulated both mRNA and protein expression levels of the cytokines tumor necrosis factor-α, interleukin (IL)-1β, and IL-6. CAI also significantly reduced the increased DNA-binding activity of nuclear factor (NF)-κB induced by LPS stimulation. With respect to the mechanisms involved on NF-κB activity, CAI exhibited suppression of the phosphorylation and degradation of the inhibitor of nuclear factor-κBα (IκB), and decreased the phosphorylation levels of the p65 subunit and its subsequent nuclear translocation. In addition, CAI significantly decreased the phosphorylated forms of p38, JNK and ERK, which were increased following LPS stimulation, while the total expression levels of p38, JNK and ERK remained unaltered. The results in the present study indicate that CAI alleviates the inflammatory responses of RAW 264.7 macrophages in response to LPS stimulation via attenuating the activation of NF-κB and MAPK signaling pathways and decreasing the levels of pro-inflammatory mediators. This offers a novel perspective for understanding the anti-inflammatory mechanism of CAI and suggests its potential use as a therapeutic treatment in inflammatory diseases with excessive macrophage activation.

IL-1β dominates the promucin secretory cytokine profile in cystic fibrosis

Cystic fibrosis (CF) lung disease is characterized by early and persistent mucus accumulation and neutrophilic inflammation in the distal airways. Identification of the factors in CF mucopurulent secretions that perpetuate CF mucoinflammation may provide strategies for novel CF pharmacotherapies. We show that IL-1β, with IL-1α, dominated the mucin prosecretory activities of supernatants of airway mucopurulent secretions (SAMS). Like SAMS, IL-1β alone induced MUC5B and MUC5AC protein secretion and mucus hyperconcentration in CF human bronchial epithelial (HBE) cells. Mechanistically, IL-1β induced the sterile α motif-pointed domain containing ETS transcription factor (SPDEF) and downstream endoplasmic reticulum to nucleus signaling 2 (ERN2) to upregulate mucin gene expression. Increased mRNA levels of IL1B, SPDEF, and ERN2 were associated with increased MUC5B and MUC5AC expression in the distal airways of excised CF lungs. Administration of an IL-1 receptor antagonist (IL-1Ra) blocked SAMS-induced expression of mucins and proinflammatory mediators in CF HBE cells. In conclusion, IL-1α and IL-1β are upstream components of a signaling pathway, including IL-1R1 and downstream SPDEF and ERN2, that generate a positive feedback cycle capable of producing persistent mucus hyperconcentration and IL-1α and/or IL-1β-mediated neutrophilic inflammation in the absence of infection in CF airways. Targeting this pathway therapeutically may ameliorate mucus obstruction and inflammation-induced structural damage in young CF children.

Wnt signaling modulates macrophage polarization and is regulated by biomaterial surface properties

Macrophages are among the first cells to interact with biomaterials and ultimately determine their integrative fate. Biomaterial surface characteristics like roughness and hydrophilicity can activate macrophages to an anti-inflammatory phenotype. Wnt signaling, a key cell proliferation and differentiation pathway, has been associated with dysregulated macrophage activity in disease. However, the role Wnt signaling plays in macrophage activation and response to biomaterials is unknown. The aim of this study was to characterize the regulation of Wnt signaling in macrophages during classical pro- and anti-inflammatory polarization and in their response to smooth, rough, and rough-hydrophilic titanium (Ti) surfaces. Peri-implant Wnt signaling in macrophage-ablated (MaFIA) mice instrumented with intramedullary Ti rods was significantly attenuated compared to untreated controls. Wnt ligand mRNA were upregulated in a surface modification-dependent manner in macrophages isolated from the surface of Ti implanted in C57Bl/6 mice. In vitro, Wnt mRNAs were regulated in primary murine bone-marrow-derived macrophages cultured on Ti in a surface modification-dependent manner. When macrophageal Wnt secretion was inhibited, macrophage sensitivity to both physical and biological stimuli was abrogated. Loss of macrophage-derived Wnts also impaired recruitment of mesenchymal stem cells and T-cells to Ti implants in vivo. Finally, inhibition of integrin signaling decreased surface-dependent upregulation of Wnt genes. These results suggest that Wnt signaling regulates macrophage response to biomaterials and that macrophages are an important source of Wnt ligands during inflammation and healing.

Allo-priming as a universal anti-viral vaccine: protecting elderly from current COVID-19 and any future unknown viral outbreak

BACKGROUND

We present the rationale for a novel allo-priming approach to serve the elderly as a universal anti-virus vaccine, as well serving to remodel the aging immune system in order to reverse immunosenescence and inflammaging. This approach has the potential to protect the most vulnerable from disease and provide society an incalculable economic benefit. Allo-priming healthy elderly adults is proposed to provide universal protection from progression of any type of viral infection, including protection against progression of the current outbreak of COVID-19 infection, and any future variants of the causative SARS-CoV-2 virus or the next 'Disease X'. Allo-priming is an alternative approach for the COVID-19 pandemic that provides a back-up in case vaccination strategies to elicit neutralizing antibody protection fails or fails to protect the vulnerable elderly population. The allo-priming is performed using activated, intentionally mismatched, ex vivo differentiated and expanded living Th1-like cells (AlloStim^®) derived from healthy donors currently in clinical use as an experimental cancer vaccine. Multiple intradermal injections of AlloStim^® creates a dominate titer of allo-specific Th1/CTL memory cells in circulation, replacing the dominance of exhausted memory cells of the aged immune system. Upon viral encounter, by-stander activation of the allo-specific memory cells causes an immediate release of IFN-ϒ, leading to development of an "anti-viral state", by-stander activation of innate cellular effector cells and activation of cross-reactive allo-specific CTL. In this manner, the non-specific activation of allo-specific Th1/CTL initiates a cascade of spatial and temporal immune events which act to limit the early viral titer. The release of endogenous heat shock proteins (HSP) and DAMP from lysed viral-infected cells, in the context of IFN-ϒ, creates of conditions for in situ vaccination leading to viral-specific Th1/CTL immunity. These viral-specific Th1/CTL provide sterilizing immunity and memory for protection from disease recurrence, while increasing the pool of Th1/CTL in circulation capable of responding to the next viral encounter.

CONCLUSION

Allo-priming has potential to provide universal protection from viral disease and is a strategy to reverse immunosenescence and counter-regulate chronic inflammation (inflammaging). Allo-priming can be used as an adjuvant for anti-viral vaccines and as a counter-measure for unknown biological threats and bio-economic terrorism.