Mechanosensing regulates tissue repair program in macrophages

Cancer-intrinsic Cxcl5 orchestrates a global metabolic reprogramming for resistance to oxidative cell death in 3D

Pancreatic ductal adenocarcinoma is characterized by a three-dimensional (3D) tumor microenvironment devoid of oxygen and nutrients but enriched in extracellular matrix, which acts as a physical and chemical barrier. In 3D, cancer cells reprogram their metabolic pathways in ways that help them survive hostile conditions. However, little is known about the metabolic phenotypes of cancer cells in 3D and the intrinsic cues that modulate them. We found that Cxcl5 deletion restricted pancreatic tumor growth in a 3D spheroid-in-Matrigel culture system without affecting cancer cell growth in 2D culture. Cxcl5 deletion impaired 3D-specific global metabolic reprogramming, resistance to hypoxia-induced cell death, and upregulation of Hif1α and Myc. Overexpression of Hif1α and Myc, however, effectively restored 3D culture-induced metabolic reconfiguration, growth, redox homeostasis, and mitochondrial function in Cxcl5-/- cells, reducing ferroptosis. We also found that pancreatic cancer patients with higher expression of hypoxia and metabolism-related genes whose expression is well-correlated with CXCL5 generally have poorer prognosis. Together, our findings identify an unanticipated role of Cxcl5 in orchestrating the cancer metabolic reprogramming in 3D culture that is required for energy and biomass maintenance and that restricts oxidative cell death. Thus, our results provide a rationale for targeting CXCL5 as a promising therapeutic strategy.

Molecular mechanism on autophagy associated cardiovascular dysfunction in Drosophila melanogaster

As a highly conserved cellular process, autophagy has been the focus of extensive research due to its critical role in maintaining cellular homeostasis and its implications in cardiovascular pathogenesis. The decline in muscular function, along with the neuronal system, and increased sensitivity to stress have been recognized in multiple animal models. Autophagic defects in cardiovascular architecture and cellular dysfunction have been linked to both physiological and pathological conditions of the heart in mammals and Drosophila. In this review, we systematically analyze the autophagy-associated pathways in the hearts of fruit flies and aim to provide a comprehensive understanding for developing potential treatments for patients and effective strategies for agricultural applications. This analysis elucidates the molecular mechanisms of autophagy in cardiovascular function under both physiological and pathological conditions in Drosophila, offering significant insights into the development of cardiovascular diseases. The loss of key autophagy-associated proteins, including the transmembrane protein Atg9 and its partners Atg2 or Atg18, along with DmSestrin, leads to cardiac hypertrophy and structural abnormalities in Drosophila, resembling the age-dependent deterioration of cardiac function. Members of the autophagy-related (Atg) gene family, cellular or nuclear skeletal lamins, and the mechanistic or mammalian target of rapamycin (mTOR) signaling pathways are critically influential in heart function in Drosophila, with autophagy activation shown to suppress cardiac laminopathy. The mTORC1/C2 complexes, along with axis of Atg2-AMPK/Sirt1/PGC-1α pathway, are essential in the hearts of both mammals and fruit flies, governing cardiac development, growth, maturation, and the maintenance of cardiac homeostasis. The beneficial effects of several interventions that enhance cardiac function, including exercise and cold stress, can influence autophagy-dependent TOR activity of the serine/threonine protein kinase signaling in both mammals and Drosophila. Exercise has been shown to increase autophagy when it is deficient and to inhibit it when it is excessive, highlighting the dual role of autophagy in cardiac health. This review evaluates the functional significance of autophagy in the heart, particularly in the context of Drosophila, in relation to mTORC-associated autophagy and the axis of Atg2-AMPK/Sirt1/PGC-1α pathways. It systematically contrasts the molecular mechanisms underlying autophagy-related cardiovascular physiological and pathological conditions in both fruit flies and mammals. The evolutionary conservation of autophagy underscores the value of Drosophila as a model for understanding broader mechanisms of autophagy across species. This study not only deepens our understanding of autophagy's role in cardiovascular function but also provides a theoretical foundation for the potential application of autophagy in agricultural pest control.

The Intersection between Immune System and Idiopathic Pulmonary Fibrosis-A Concise Review

Idiopathic pulmonary fibrosis (IPF) is marked by progressive alveolar destruction, impaired tissue regeneration, and relentless fibrogenesis, culminating in respiratory failure and death. A diverse array of resident and non-resident cells within the lung contribute to disease pathogenesis. Notably, immune cells, both resident and recruited, respond to cues from sites of lung injury by undergoing phenotypic transitions and producing a wide range of mediators that influence, initiate, or dictate the function, or dysfunction, of key effector cells in IPF pathology, such as alveolar epithelial cells, lung fibroblasts, and capillary endothelial cells. The role of the immune system in IPF has undergone an interesting evolution, oscillating from initial enthusiasm to skepticism, and now to a renewed focus. This shift reflects both the past failures of immune-targeting therapies for IPF and the unprecedented insights into immune cell heterogeneity provided by emerging technologies. In this article, we review the historical evolution of perspectives on the immune system's role in IPF pathogenesis and examine the lessons learned from previous therapeutic failures targeting immune responses. We discuss the major immune cell types implicated in IPF progression, highlighting their phenotypic transitions and mechanisms of action. Finally, we identify key knowledge gaps and propose future directions for research on the immune system in IPF.

Eu-Doped TiO2 Coatings via One-Step In Situ Preparation Enhance Macrophage Polarization and Osseointegration of Implants

The controllable regulation of immune and osteogenic processes plays a critical role in the modification of biocompatible materials for tissue regeneration. In this study, titanium dioxide-europium coatings (MAO/Eu) were prepared on the surface of a titanium alloy (Ti-6Al-4V) via a one-step process combining microarc oxidation (MAO) and in situ doping. The incorporation of Eu significantly improved the hydrophilic and mechanical properties of the TiO2 coatings without altering their morphology. The presence of Eu effectively stimulated calcium influx in macrophages and activated β-catenin through the wnt/β-catenin signaling pathway. Consequently, macrophage M2 polarization was accelerated through the overexpression of prostaglandin E2 (PGE2). Additionally, Ca2+ promoted the osteogenic differentiation of MC3T3-E1 cells through the synergistic upregulation of transcription factors (e.g., AP-1, BMP-2). In vivo studies demonstrated that MAO/Eu coatings significantly enhanced osseointegration compared with the titanium alloy group. Therefore, MAO/Eu shows promising potential as an ideal coating for implants that offers effective immunomodulatory strategies and improves bone integration.

Mild Hyperthermia Accelerates Bone Repair by Dynamically Regulating iNOS/Arg1 Balance in the Early Stage

Mild hyperthermia therapy has garnered interest as an adjunctive treatment for bone repair. However, its optimal timing, duration, and underlying mechanisms remain unclear. In this study, how mild hyperthermia supports bone repair during the early stages is assesed. These findings reveal that mild hyperthermia accelerates bone regeneration by dynamically regulating inducible nitric oxide synthase/arginase 1 (iNOS/Arg1) balance. This process involves macrophage polarization to the M1 phenotype through iNOS activation, followed by a rapid transition to the M2 phenotype through Arg1 activation after 3 days of sustained mild hyperthermia. RNA-Seq reveals that a single day of mild hyperthermia induced immune alterations aligned with the early inflammatory phase of bone repair, characterized by osteoclast activation, cell recruitment, and neovascularization, thereby preparing for the transition to the repair phase. Experiments involving subcutaneous abscesses, subcutaneous embedding, and critical cranial bone defects further confirm that early mild hyperthermia treatment dynamically regulates macrophage phenotypes. This regulation enhances early antibacterial activity, promotes angiogenesis, and facilitates the transition from inflammation to repair, ultimately accelerating bone-defect repair. This study is the first to elucidate the dual temporal effects of early mild hyperthermia on immune regulation, offering insights into the optimal timing and duration of photothermal therapy following bone repair surgery.

Cranial bone maneuver ameliorates Alzheimer's disease pathology via enhancing meningeal lymphatic drainage function

INTRODUCTION

Alzheimer's disease (AD) is a progressive neurodegenerative disease and the leading cause of dementia. Recent research highlights meningeal lymphatics as key regulators in neurological diseases, suggesting that enhancing their drainage function could be a potential therapeutic strategy for AD. Our proof-of-concept study demonstrated that cranial bone transport can improve meningeal lymphatic drainage function and promote ischemic stroke recovery.

METHODS

This study defined cranial bone maneuver (CBM) technique. After osteotomy, a small circular bone flap was made and attached to an external fixator for subsequent maneuver in a controlled fashion for a defined period using 5xFAD mice.

RESULTS

CBM treatment improved memory functions, reduced amyloid deposits, and promoted meningeal lymphatic drainage function. CBM induced cascades of inflammatory and lymphangiogenic processes in skull and meninges. Meningeal lymphatics are indispensable elements for the therapeutic effects of CBM.

DISCUSSION

CBM might be a promising innovative therapy for AD management, warranting further clinical investigation.

HIGHLIGHTS

Cranial bone maneuver (CBM) alleviated memory deficits and amyloid depositions. CBM promoted meningeal lymphangiogenesis and lymphatic drainage function. The beneficial effects of CBM lasted for a long time following the CBM procedures. CBM induced cascades of inflammatory and lymphangiogenic processes in the meninges. Meningeal lymphatic vessels are indispensable elements for CBM therapeutic effects.

Inhibition of Mitochondrial Succinate Dehydrogenase with Dimethyl Malonate Promotes M2 Macrophage Polarization by Enhancing STAT6 Activation

Macrophages exhibit diverse phenotypes depending on environment status, which contribute to physiological and pathological processes of immunological diseases, including sepsis, asthma, multiple sclerosis and colitis. The alternative activation of macrophages is tightly regulated to avoid excessive activation and damage of tissues and organs. Certain works characterized that succinate dehydrogenase (SDH) altered function of macrophages and promoted inflammatory response in M1 macrophages via mitochondrial reactive oxygen species (ROS). However, the effect of succinate dehydrogenase on M2 macrophage polarization remains incompletely understood. We employed dimethyl malonate (DMM) to inhibit succinate dehydrogenase activity and took use of RNA-seq to analyze the changes of inflammatory response of LPS-activated M1 macrophages or IL 4-activated M2 macrophages. Our data revealed that inhibition of SDH with DMM increased expression of M2 macrophages-associated signature genes, including Arg1, Ym1 and Mrc1. Consistent with previous work, we also observed that inhibition of SDH decreased the expression of IL-1β and enhanced the levels of IL-10 in M1 macrophages. Additionally, inhibition of SDH with DMM inhibited the production of chemokines, such as Cxcl3, Cxcl12, Ccl20 and Ccl9. DMM also amplified the M2 macrophages-related signature genes in IL-13-activated M2 macrophages. Mechanistic studies revealed that DMM promoted M2 macrophages polarization through mitochondrial ROS dependent STAT6 activation. Blocking ROS with mitoTEMPO or inhibiting STAT6 activation with ruxolitinib abrogated the promotion effect of DMM on M2 macrophages. Finally, dimethyl malonate treatment promoted peritoneal M2 macrophages differentiation and exacerbated OVA-induced allergy asthma in vivo. Collectively, we identified SDH as a braker to suppress M2 macrophage polarization via mitochondrial ROS, suggesting a novel strategy to treatment of M2 macrophages-mediated inflammatory diseases.

Manipulating immune activity of macrophages: a materials and mechanics perspective

Macrophage immune cells exist on a plastic spectrum of phenotypes governed by their physical and biochemical environment. Controlling macrophage function to facilitate immunological regeneration or fighting pathology has emerged as a therapeutic possibility. The rate-limiting step in translating macrophage immunomodulation therapies has been the absence of fundamental knowledge of how physics and biochemistry in the macrophage microenvironment converge to inform phenotype. In this review we explore recent trends in bioengineered model systems that integrate physical and biochemical variables applied to macrophage mechanosensing and plasticity. We focus on how tuning of mechanical forces and biomaterial composition orchestrate macrophage function in physiological and pathological contexts. Ultimately, a broader understanding of stimuli-responsiveness in macrophages leads to informed design for future modulatory therapies.

Flexible and multi-functional three-dimensional scaffold based on enokitake-like Au nanowires for real-time monitoring of endothelial mechanotransduction

Endothelial cells are sensitive to mechanical force and can convert it into biochemical signals to trigger mechano-chemo-transduction. Although conventional techniques have been used to investigate the subsequent modifications of cellular expression after mechanical stimulation, the in situ and real-time acquiring the transient biochemical information during mechanotransduction process remains an enormous challenge. In this work, we develop a flexible and multi-functional three-dimensional conductive scaffold that integrates cell growth, mechanical stimulation, and electrochemical sensing by in situ growth of enokitake-like Au nanowires on a three-dimensional porous polydimethylsiloxane substrate. The conductive scaffold possesses stable and desirable electrochemical sensing performance toward nitric oxide under mechanical deformation. The prepared e-AuNWs/CC/PDMS scaffold exhibits a good electrocatalytic ability to NO with a linear range from 2.5 nM to 13.95 μM and a detection limit of 8 nM. Owing to the excellent cellular compatibility, endothelial cells can be cultured directly on the scaffold and the real-time inducing and recording of nitric oxide secretion under physiological and pathological conditions were achieved. This work renders a reliable sensing platform for real-time monitoring cytomechanical signaling during endothelial mechanotransduction and is expected to promote other related biological investigations based on three-dimensional cell culture.

Acute contact with profibrotic macrophages mechanically activates fibroblasts via αvβ3 integrin-mediated engagement of Piezo1

Fibrosis-excessive scarring after injury-causes >40% of disease-related deaths worldwide. In this misguided repair process, activated fibroblasts drive the destruction of organ architecture by accumulating and contracting extracellular matrix. The resulting stiff scar tissue, in turn, enhances fibroblast contraction-bearing the question of how this positive feedback loop begins. We show that direct contact with profibrotic but not proinflammatory macrophages triggers acute fibroblast contractions. The contractile response depends on αvβ3 integrin expression on macrophages and Piezo1 expression on fibroblasts. The touch of macrophages elevates fibroblast cytosolic calcium within seconds, followed by translocation of the transcription cofactors nuclear factor of activated T cells 1 and Yes-associated protein, which drive fibroblast activation within hours. Intriguingly, macrophages induce mechanical stress in fibroblasts on soft matrix that alone suppresses their spontaneous activation. We propose that acute contact with suitable macrophages mechanically kick-starts fibroblast activation in an otherwise nonpermissive soft environment. The molecular components mediating macrophage-fibroblast mechanotransduction are potential targets for antifibrosis strategies.

The role of the cytoskeleton in fibrotic diseases

Fibrosis is the process whereby cells at a damaged site are transformed into fibrotic tissue, comprising fibroblasts and an extracellular matrix rich in collagen and fibronectin, following damage to organs or tissues that exceeds their repair capacity. Depending on the affected organs or tissues, fibrosis can be classified into types such as pulmonary fibrosis, hepatic fibrosis, renal fibrosis, and cardiac fibrosis. The primary pathological features of fibrotic diseases include recurrent damage to normal cells and the abnormal activation of fibroblasts, leading to excessive deposition of extracellular matrix and collagen in the intercellular spaces. However, the etiology of certain specific fibrotic diseases remains unclear. Recent research increasingly suggests that the cytoskeleton plays a significant role in fibrotic diseases, with structural changes in the cytoskeleton potentially influencing the progression of organ fibrosis. This review examines cytoskeletal remodeling and its impact on the transformation or activation of normal tissue cells during fibrosis, potentially offering important insights into the etiology and therapeutic strategies for fibrotic diseases.

Development of Biomaterials to Modulate the Function of Macrophages in Wound Healing

Wound healing is a complex and precisely regulated process that encompasses multiple stages, including inflammation, anti-inflammation, and tissue repair. It involves various cells and signaling molecules, with macrophages demonstrating a significant degree of plasticity and playing a crucial regulatory role at different stages. In recent years, the use of biomaterials, which include both natural and synthetic polymers or macromolecules, has proliferated for the purpose of enhancing wound healing. This review summarizes how these diverse biomaterials promote wound healing by modulating macrophage behavior and examines the broader implications of these modulations. Additionally, we discuss the limitations associated with the clinical application of immunomodulatory biomaterials and propose potential solutions. Finally, we look towards future developments in the design of immunomodulatory biomaterials intended to enhance wound healing.

Macrophage variants in laboratory research: most are well done, but some are RAW

Macrophages play a pivotal role in the innate immune response. While their most characteristic function is phagocytosis, it is important not to solely characterize macrophages by this activity. Their crucial roles in body development, homeostasis, repair, and immune responses against pathogens necessitate a broader understanding. Macrophages exhibit remarkable plasticity, allowing them to modify their functional characteristics in response to the tissue microenvironment (tissue type, presence of pathogens or inflammation, and specific signals from neighboring cells) swiftly. While there is no single defined "macrophage" entity, there is a diverse array of macrophage types because macrophage ontogeny involves the differentiation of progenitor cells into tissue-resident macrophages, as well as the recruitment and differentiation of circulating monocytes in response to tissue-specific cues. In addition, macrophages continuously sense and respond to environmental cues and tissue conditions, adjusting their functional and metabolic states accordingly. Consequently, it is of paramount importance to comprehend the heterogeneous origins and functions of macrophages employed in in vitro studies, as each available in vitro macrophage model is associated with specific sets of strengths and limitations. This review centers its attention on a comprehensive comparison between immortalized mouse macrophage cell lines and primary mouse macrophages. It provides a detailed analysis of the strengths and weaknesses inherent in these in vitro models. Finally, it explores the subtle distinctions between diverse macrophage cell lines, offering insights into numerous factors beyond the model type that can profoundly influence macrophage function.

Novel 3-D Macrophage Spheroid Model Reveals Reciprocal Regulation of Immunomechanical Stress and Mechano-Immunological Response

Purpose

In many diseases, an overabundance of macrophages contributes to adverse outcomes. While numerous studies have compared macrophage phenotype after mechanical stimulation or with varying local stiffness, it is unclear if and how macrophages directly contribute to mechanical forces in their microenvironment.

Methods

Raw 264.7 murine macrophages were embedded in a confining agarose gel, and proliferated to form spheroids over days/weeks. Gels were synthesized at various concentrations to tune stiffness and were shown to support cell viability and spheroid growth. These cell-agarose constructs were treated with media supplements to promote macrophage polarization. Spheroid geometries were used to computationally model the strain generated in the agarose by macrophage spheroid growth. Agarose-embedded macrophages were analyzed for viability, spheroid size, stress generation, and gene expression.

Results

Macrophages form spheroids and generate growth-induced mechanical forces (i.e., solid stress) within confining agarose gels, which can be maintained for at least 16 days in culture. Increasing agarose concentration increases gel stiffness, restricts spheroid expansion, limits gel deformation, and causes a decrease in Ki67 expression. Lipopolysaccharide (LPS) stimulation increases spheroid growth, though this effect is reversed with the addition of IFNγ. The mechanosensitive ion channels Piezo1 and TRPV4 have reduced expression with increased stiffness, externally applied compression, LPS stimulation, and M1-like polarization.

Conclusions

Macrophages alone both respond to and generate solid stress. Understanding how macrophage generation of growth-induced solid stress responds to different environmental conditions will help to inform treatment strategies for the plethora of diseases that involve macrophage accumulation and inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-024-00824-z.

Transcriptomic and Multi-scale Network Analyses Reveal Key Drivers of Cardiovascular Disease

Cardiovascular diseases (CVDs) and pathologies are often driven by changes in molecular signaling and communication, as well as in cellular and tissue components, particularly those involving the extracellular matrix (ECM), cytoskeleton, and immune response. The fine-wire vascular injury model is commonly used to study neointimal hyperplasia and vessel stiffening, but it is not typically considered a model for CVDs. In this paper, we hypothesize that vascular injury induces changes in gene expression, molecular communication, and biological processes similar to those observed in CVDs at both the transcriptome and protein levels. To investigate this, we analyzed gene expression in microarray datasets from injured and uninjured femoral arteries in mice two weeks post-injury, identifying 1,467 significantly and differentially expressed genes involved in several CVDs such as including vaso-occlusion, arrhythmia, and atherosclerosis. We further constructed a protein-protein interaction network with seven functionally distinct clusters, with notable enrichment in ECM, metabolic processes, actin-based process, and immune response. Significant molecular communications were observed between the clusters, most prominently among those involved in ECM and cytoskeleton organizations, inflammation, and cell cycle. Machine Learning Disease pathway analysis revealed that vascular injury-induced crosstalk between ECM remodeling and immune response clusters contributed to aortic aneurysm, neovascularization of choroid, and kidney failure. Additionally, we found that interactions between ECM and actin cytoskeletal reorganization clusters were linked to cardiac damage, carotid artery occlusion, and cardiac lesions. Overall, through multi-scale bioinformatic analyses, we demonstrated the robustness of the vascular injury model in eliciting transcriptomic and molecular network changes associated with CVDs, highlighting its potential for use in cardiovascular research.

The immunomicrotope of Leishmania control and persistence

Leishmania is an intracellular protozoan transmitted by sand fly vectors; it causes cutaneous, mucocutaneous, or visceral disease. Its growth and survival are impeded by type 1 T helper cell responses, which entail interferon (IFN)-γ-mediated macrophage activation. Leishmania partially escapes this host defense by triggering immune cell and cytokine responses that favor parasite replication rather than killing. Novel methods for in situ analyses have revealed that the pathways of immune control and microbial evasion are strongly influenced by the tissue context, the micro milieu factors, and the metabolism at the site of infection, which we collectively term the 'immunomicrotope'. Understanding the components and the impact of the immunomicrotope will enable the development of novel strategies for the treatment of chronic leishmaniasis.

Mechanoimmune-Driven Backpack Sustains Dendritic Cell Maturation for Synergistic Tumor Radiotherapy

Cell backpacks present significant potential in both therapeutic and diagnostic applications, making it essential to further explore their interactions with host cells. Current evidence indicates that backpacks can induce sustained immune responses. Our original objective was to incorporate a model antigen into the backpacks to promote dendritic cell maturation and facilitate antigen presentation, thereby inducing immune responses. However, we unexpectedly discovered that both antigen-loaded backpacks and empty backpacks demonstrated comparable abilities to induce dendritic cell maturation, resulting in nearly identical potency in T-cell proliferation. Our mechanistic studies suggest that the attachment of backpacks induces mechanical forces on dendritic cells via opening the PIEZO1 mechanical ion channel. This interaction leads to the remodeling of the intracellular cytoskeleton and facilitates the production of type I interferons by dendritic cells. Consequently, the mechano-immune-driven dendritic cell backpacks, when combined with radiotherapy, induce a robust antitumor effect. This research presents an avenue for leveraging mechanotransduction to enhance combination immunotherapeutic strategies, potentially leading to groundbreaking advancements in the field.