Processes of sterile inflammation

Natural polysaccharides as promising reno-protective agents for the treatment of various kidney injury

Renal injury, a prevalent clinical outcome with multifactorial etiology, imposes a substantial burden on society. Currently, there remains a lack of effective management and treatments. Extensive research has emphasized the diverse biological effects of natural polysaccharides, which exhibit promising potential for mitigating renal damage. This review commences with the pathogenesis of four common renal diseases and the shared mechanisms underlying renal injury. The renoprotective roles of polysaccharides in vivo and in vitro are summarized in the following five aspects: anti-oxidative stress effects, anti-apoptotic effects, anti-inflammatory effects, anti-fibrotic effects, and gut modulatory effects. Furthermore, we explore the structure-activity relationship and bioavailability of polysaccharides in relation to renal injury, as well as investigate their utility as biomaterials for alleviating renal injury. The clinical experiments of polysaccharides applied to patients with chronic kidney disease are also reviewed. Broadly, this review provides a comprehensive perspective on the research direction of natural polysaccharides in the context of renal injury, with the primary aim to serve as a reference for the clinical development of polysaccharides as pharmaceuticals and prebiotics for the treatment of kidney diseases.

Role of Neutrophils in the Development of Steatotic Liver Disease

This review explores the biological aspects of neutrophils, their contributions to the development of steatotic liver disease, and their potential as therapeutic targets for the disease. Although alcohol-associated and metabolic dysfunction-associated liver diseases originate from distinct etiological factors, the two diseases frequently share excessive lipid accumulation as a common contributor to their pathogenesis, thereby classifying them as types of steatotic liver disease. Dysregulated lipid deposition in the liver induces hepatic injury, triggering the activation of the innate immunity, partially through neutrophil recruitment. Traditionally recognized for their role in microbial clearance, neutrophils have recently garnered attention for their involvement in sterile inflammation, a pivotal component of steatotic liver disease pathogenesis. In conclusion, technological innovations, including single-cell RNA sequencing, have gradually disclosed the existence of various neutrophil subsets; however, how the distinct subsets of neutrophil population contribute differentially to the development of steatotic liver disease remains unclear.

Skeletal Muscle UCHL1 Negatively Regulates Muscle Development and Recovery after Muscle Injury

Ubiquitin C-terminal hydrolase L1 (UCHL1) is a deubiquitinating enzyme originally found in the brain. Our previous work revealed that UCHL1 was also expressed in skeletal muscle and affected myoblast differentiation and metabolism. In this study, we further tested the role of UCHL1 in myogenesis and muscle regeneration following muscle ischemia-reperfusion (IR) injury. In the C2C12 myoblast, UCHL1 knockdown upregulated MyoD and myogenin and promoted myotube formation. The skeletal muscle-specific knockout (smKO) of UCHL1 increased muscle fiber sizes in young mice (1 to 2 months old) but not in adult mice (3 months old). In IR-injured hindlimb muscle, UCHL1 was upregulated. UCHL1 smKO ameliorated tissue damage and injury-induced inflammation. UCHL1 smKO also upregulated myogenic factors and promoted functional recovery in IR injury muscle. Moreover, UCHL1 smKO increased Akt and Pink1/Parkin activities. The overall results suggest that skeletal muscle UCHL1 is a negative factor in skeletal muscle development and recovery following IR injury and therefore is a potential therapeutic target to improve muscle regeneration and functional recovery following injuries.

Mitochondria and NLRP3 inflammasome in cardiac hypertrophy

Cardiac hypertrophy is the main adaptive response of the heart to chronic loads; however, prolonged or excessive hypertrophy promotes myocardial interstitial fibrosis, systolic dysfunction, and cardiomyocyte death, especially aseptic inflammation mediated by NLRP3 inflammasome, which can aggravate ventricular remodeling and myocardial damage, which is an important mechanism for the progression of heart failure. Various cardiac overloads can cause mitochondrial damage. In recent years, the mitochondria have been demonstrated to be involved in the inflammatory response during the development of cardiac hypertrophy in vitro and in vivo. As the NLRP3 inflammasome and mitochondria are regulators of inflammation and cardiac hypertrophy, we explored the potential functions of the NLRP3 inflammasome and mitochondrial dysfunction in cardiac hypertrophy. In particular, we proposed that the induction of mitochondrial dysfunction in cardiomyocytes may promote NLRP3-dependent inflammation during myocardial hypertrophy. Further in-depth studies could prompt valuable discoveries regarding the underlying molecular mechanisms of cardiac hypertrophy, reveal novel anti-inflammatory therapies for cardiac hypertrophy, and provide more desirable therapeutic outcomes for patients with cardiac hypertrophy.

Deleting Mitochondrial Superoxide Dismutase 2 in Salivary Gland Ductal Epithelial Cells Recapitulates Non-Sjögren's Sicca Syndrome

Elevated oxidative stress can play a pivotal role in autoimmune diseases by exacerbating inflammatory responses and tissue damage. In Sjögren's disease (SjD), the contribution of oxidative stress in the disease pathogenesis remains unclear. To address this question, we created mice with a tamoxifen-inducible conditional knockout (KO) of a critical antioxidant enzyme, superoxide dismutase 2 (Sod2), in the salivary glands (i-sg-Sod2 KO mice). Following tamoxifen treatment, Sod2 deletion occurred primarily in the ductal epithelium, and the salivary glands showed a significant downregulation of Sod2 expression. At twelve weeks post-treatment, salivary glands from the i-sg-Sod2 KO mice exhibited increased 3-Nitrotyrosine staining. Bulk RNA-seq revealed alterations in gene expression pathways related to ribosome biogenesis, mitochondrial function, and oxidative phosphorylation. Significant changes were noted in genes characteristic of salivary gland ionocytes. The i-sg-Sod2 KO mice developed reversible glandular hypofunction. However, this functional loss was not accompanied by glandular lymphocytic foci or circulating anti-nuclear antibodies. These data demonstrate that although localized oxidative stress in salivary gland ductal cells was insufficient for SjD development, it induced glandular dysfunction. The i-sg-Sod2 KO mouse resembles patients classified as non-Sjögren's sicca and will be a valuable model for deciphering oxidative-stress-mediated glandular dysfunction and recovery mechanisms.

Terpenes in the management of chronic kidney disease

Chronic kidney disease (CKD) is a chronic and progressive systemic condition that characterizes irreversible alterations in the kidneys' function and structure over an extended period, spanning months to years. CKD is the one of the major causes of mortality worldwide. However, very limited treatment options are available in the market for management of the CKD. Diabetes and hypertension are the key risk factors for the progression of CKD. It is majorly characterised by glomerulosclerosis, tubular atrophy, and interstitial fibrosis. Plants are considered safe and effective in treating various chronic conditions. A diverse group of phytoconstituents, including polyphenols, flavonoids, alkaloids, tannins, saponins, and terpenes, have found significant benefits in managing chronic ailments. Terpenes constitute a diverse group of plant compounds with various therapeutic benefits. Evidence-based pharmacological studies underscore the crucial role played by terpenes in preventing and managing CKD. These substances demonstrate the capacity to hinder detrimental pathways, such as oxidative stress, inflammation and fibrosis, thereby demonstrating benefit in renal dysfunction. This review offers a comprehensive overview of the roles and positive attributes of commonly occurring terpenes in managing the causes and risk factors of CKD and the associated conditions.

Tissue-Resident Macrophages in Solid Organ Transplantation: Harmful or Protective?

Transplanted organs carry donor immune cells into the recipient, the majority of which are tissue-resident macrophages (TRMs). The role they play in guiding the fate of the transplanted organ toward acceptance or rejection remains elusive. TRMs originate from both embryonic and bone marrow-derived precursors. Embryo-derived TRMs retain the embryonic capability to proliferate, so they are able to self-renew and, theoretically, persist for extended periods of time after transplantation. Bone marrow-derived TRMs do not proliferate and must constantly be replenished by adult circulating monocytes. Recent studies have aimed to clarify the different roles and interactions between donor TRMs, recipient monocytes, and monocyte-derived macrophages (MFs) after organ transplantation. This review aims to shed light on how MFs affect the fate of a transplanted organ by differentiating between the role of donor TRMs and that of MFs derived from graft infiltrating monocytes.

Targeting Macrophages in Organ Transplantation: A Step Toward Personalized Medicine

Organ transplantation remains the most optimal strategy for patients with end-stage organ failure. However, prevailing methods of immunosuppression are marred by adverse side effects, and allograft rejection remains common. It is imperative to identify and comprehensively characterize the cell types involved in allograft rejection, and develop therapies with greater specificity. There is increasing recognition that processes mediating allograft rejection are the result of interactions between innate and adaptive immune cells. Macrophages are heterogeneous innate immune cells with diverse functions that contribute to ischemia-reperfusion injury, acute rejection, and chronic rejection. Macrophages are inflammatory cells capable of innate allorecognition that strengthen their responses to secondary exposures over time via "trained immunity." However, macrophages also adopt immunoregulatory phenotypes and may promote allograft tolerance. In this review, we discuss the roles of macrophages in rejection and tolerance, and detail how macrophage plasticity and polarization influence transplantation outcomes. A comprehensive understanding of macrophages in transplant will guide future personalized approaches to therapies aimed at facilitating tolerance or mitigating the rejection process.

Role of HIF in fish inflammation

The hypoxia-inducing factor (HIF) is a central transcription factor in cellular oxygen sensing and regulation. It is common that the inflammation always appears in many diseases, like infectious diseases in fishes, and the inflammation is often accompanied by hypoxia, as a hallmark of inflammation. Besides coordinating cellular responses to low oxygen, HIF-mediated hypoxia signaling pathway is also crucial for immune responses such as the regulations of innate immune cell phenotype and function, as well as metabolic reprogramming under the inflammation. However, the understanding of the molecular mechanisms by which HIFs regulate the inflammatory response in fish is still very limited. Here, we review the characteristics of HIF as well as its roles in innate immune cells and the infections caused by bacteria and viruses. The regulatory effects of HIF on the metabolic reprogramming of innate immune cells are also discussed and the future research directions are outlooked. This paper will serve as a reference for elucidating the molecular mechanism of HIF regulating inflammation and identifying treatment strategies to target HIF for fish disease.

Impact of nanoparticles on human health and disease

Nanoparticles (NPs) are small particles with a surface area ranging from 1 to 100 nm in diameter that are rampantly used in different fields, e.g., medicine, engineering, and others. Because of their unique properties, such as their tiny size, magnetic properties, quantum size effects, and macroscopic quantum tunnelling effects, they are crucial for a wide range of potential applications. NPs play a significant role in the treatment of vascular disorders, the production of vaccines, and the development of drug carriers for diverse therapies due to their bioavailability, targeting ability, and efficacy. However, significant risks to the environment and health are also associated with it. NPs cause necrotic plasma membrane rupture or apoptosis, which leads to cell death. NPs interfere with cell signalling, endosomal membranes, and organelles like the nucleus or mitochondria, affecting their function. NPs cause autophagic cell death, which causes a stress response and sterile inflammation. The primary routes for the entry of NPs into the human body are inhalation, ingestion, and skin contact. NPs accumulate in the respiratory system based on their size, shape, and surface properties. NPs can cause lung inflammation and fibrosis, disrupt the endocrine system by attaching to hormone receptors, and produce reactive oxygen species (ROS) associated with DNA damage, oligospermia, and male infertility. Carcinogenic properties of NPs cause mutations, apoptosis, and inflammatory responses. Collaborative research between ecologists and epidemiologists may enlighten ways to reduce the harmful effects of NPs.

TLR2 mediates renal apoptosis in neonatal mice subjected experimentally to obstructive nephropathy

Urinary tract obstruction during renal development leads to inflammation, tubular apoptosis, and interstitial fibrosis. Toll like receptors (TLRs) expressed on leukocytes, myofibroblasts and renal cells play a central role in acute inflammation. TLR2 is activated by endogenous danger signals in the kidney; its contribution to renal injury in early life is still a controversial topic. We analyzed TLR2 for a potential role in the neonatal mouse model of congenital obstructive nephropathy. Inborn obstructive nephropathies are a leading cause of end-stage kidney disease in children. Thus, newborn Tlr2-/- and wild type (WT) C57BL/6 mice were subjected to complete unilateral ureteral obstruction (UUO) or sham-operation on the 2nd day of life. The neonatal kidneys were harvested and analyzed at days 7 and 14 of life. Relative expression levels of TLR2, caspase-8, Bcl-2, Bax, GSDMD, GSDME, HMGB1, TNF, galectin-3, α-SMA, MMP-2, and TGF-β proteins were quantified semi-quantitatively by immunoblot analyses. Tubular apoptosis, proliferation, macrophage- and T-cell infiltration, tubular atrophy, and interstitial fibrosis were analyzed immunohistochemically. Neonatal Tlr2-/- mice kidneys exhibited less tubular and interstitial apoptosis as compared to those of WT C57BL/6 mice after UUO. UUO induced neonatally did trigger pyroptosis in kidneys, however to similar degrees in Tlr2-/- and WT mice. Also, tubular atrophy, interstitial fibrosis, tubular proliferation, as well as macrophage and T-cell infiltration were unremarkable. We conclude that while TLR2 mediates apoptosis in the kidneys of neonatal mice subjected to UUO, leukocyte recruitment, interstitial fibrosis, and consequent neonatal obstructive nephropathy might lack a TLR2 involvement.

Being Eaten Alive: How Energy-Deprived Cells Are Disposed of, Mediated by C-Reactive Protein-Including a Treatment Option

In medicine, C-reactive protein (CRP) has become established primarily as a biomarker, predicting patient prognosis in many indications. Recently, however, there has been mounting evidence that it causes inflammatory injury. As early as 1999, CRP was shown to induce cell death after acute myocardial infarction (AMI) in rats and this was found to be dependent on complement. The pathological effect of CRP was subsequently confirmed in further animal species such as rabbit, mouse and pig. A conceptual gap was recently closed when it was demonstrated that ischemia in AMI or ischemia/hypoxia in the severe course of COVID-19 causes a drastic lack of energy in involved cells, resulting in an apoptotic presentation because these cells cannot repair/flip-flop altered lipids. The deprivation of energy leads to extensive expression on the cell membranes of the CRP ligand lysophosphatidylcholine. Upon attachment of CRP to this ligand, the classical complement pathway is triggered leading to the swift elimination of viable cells with the appearance of an apoptotic cell by phagocytes. They are being eaten alive. This, consequently, results in substantial fibrotic remodeling within the involved tissue. Inhibiting this pathomechanism via CRP-targeting therapy has been shown to be beneficial in different indications.

Pharmacology of a Potent and Novel Inhibitor of the NOD-Like Receptor Pyrin Domain-Containing Protein 3 (NLRP3) Inflammasome that Attenuates Development of Nonalcoholic Steatohepatitis and Liver Fibrosis

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome is a multiprotein complex and component of the innate immune system that is activated by exogenous and endogenous danger signals to promote activation of caspase-1 and the maturation and release of the proinflammatory cytokines interleukin (IL)-1β and IL-18. Inappropriate activation of NLRP3 has been implicated in the pathophysiology of multiple inflammatory and autoimmune diseases, including cardiovascular disease, neurodegenerative diseases, and nonalcoholic steatohepatitis (NASH), thus increasing the clinical interest of this target. We describe in this study the preclinical pharmacologic, pharmacokinetic, and pharmacodynamic properties of a novel and highly specific NLRP3 inhibitor, JT001 (6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine-3-sulfonylurea). In cell-based assays, JT001 potently and selectively inhibited NLRP3 inflammasome assembly, resulting in the inhibition of cytokine release and the prevention of pyroptosis, a form of inflammatory cell death triggered by active caspase-1. Oral administration of JT001 to mice inhibited IL-1β production in peritoneal lavage fluid at plasma concentrations that correlated with mouse in vitro whole blood potency. Orally administered JT001 was effective in reducing hepatic inflammation in three different murine models, including the Nlrp3A350V /+CreT model of Muckle-Wells syndrome (MWS), a diet-induced obesity NASH model, and a choline-deficient diet-induced NASH model. Significant reductions in hepatic fibrosis and cell damage were also observed in the MWS and choline-deficient models. Our findings demonstrate that blockade of NLRP3 attenuates hepatic inflammation and fibrosis and support the use of JT001 to investigate the role of NLRP3 in other inflammatory disease models. SIGNIFICANCE STATEMENT: Persistent inflammasome activation is the consequence of inherited mutations of NLRP3 and results in the development of cryopyrin-associated periodic syndromes associated with severe systemic inflammation. NLRP3 is also upregulated in nonalcoholic steatohepatitis, a metabolic chronic liver disease currently missing a cure. Selective and potent inhibitors of NLRP3 hold great promise and have the potential to overcome an urgent unmet need.

A brain cytokine-independent switch in cortical activity marks the onset of sickness behavior triggered by acute peripheral inflammation

Systemic inflammation triggers protective as well as pro-inflammatory responses in the brain based on neuronal and/or cytokine signaling, and it associates with acutely and protractedly disrupted cognition. However, the multiple mechanisms underlying the peripheral-central inflammatory signaling are still not fully characterized. We used intraperitoneal (i.p.) injection of lipopolysaccharide (LPS) in freely moving mice with chronically implanted electrodes for recording of local field potentials (LFP) and electrocorticography (ECoG) in the hippocampus and neocortex, respectively. We show here that a sudden switch in the mode of network activity occurred in both areas starting at 10-15 min after the LPS injection, simultaneously with a robust change from exploration to sickness behavior. This switch in cortical mode commenced before any elevations in pro-inflammatory cytokines IL-1β, TNFα, CCL2 or IL-6 were detected in brain tissue. Thereafter, this mode dominated cortical activity for the recording period of 3 h, except for a partial and transient recovery around 40 min post-LPS. These effects were closely paralleled by changes in ECoG spectral entropy. Continuous recordings for up to 72 h showed a protracted attenuation in hippocampal activity, while neocortical activity recovered after 48 h. The acute sickness behavior recovered by 72 h post-LPS. Notably, urethane (1.3 mg/kg) administered prior to LPS blocked the early effect of LPS on cortical activity. However, experiments under urethane anesthesia which were started 24 h post-LPS (with neuroinflammation fully developed before application of urethane) showed that both theta-supratheta and fast gamma CA1 activity were reduced, DG delta activity was increased, and sharp-wave ripples were abolished. Finally, we observed that experimental compensation of inflammation-induced hypothermia 24-48 h post-LPS promoted seizures and status epilepticus; and that LPS decreased the threshold of kainate-provoked seizures beyond the duration of acute sickness behavior indicating post-acute inflammatory hyperexcitability. Taken together, the strikingly fast development and initial independence of brain cytokines of the LPS-induced cortical mode, its spectral characteristics and simultaneity in hippocampus and neocortex, as well as inhibition by pre-applied urethane, strongly suggest that the underlying mechanisms are based on activation of the afferent vagus nerve and its mainly cholinergic ascending projections to higher brain areas.

Damage-mediated macrophage polarization in sterile inflammation

Most of the leading causes of death, such as cardiovascular diseases, cancer, dementia, neurodegenerative diseases, and many more, are associated with sterile inflammation, either as a cause or a consequence of these conditions. The ability to control the progression of inflammation toward tissue resolution before it becomes chronic holds significant clinical potential. During sterile inflammation, the initiation of inflammation occurs through damage-associated molecular patterns (DAMPs) in the absence of pathogen-associated molecules. Macrophages, which are primarily localized in the tissue, play a pivotal role in sensing DAMPs. Furthermore, macrophages can also detect and respond to resolution-associated molecular patterns (RAMPs) and specific pro-resolving mediators (SPMs) during sterile inflammation. Macrophages, being highly adaptable cells, are particularly influenced by changes in the microenvironment. In response to the tissue environment, monocytes, pro-inflammatory macrophages, and pro-resolution macrophages can modulate their differentiation state. Ultimately, DAMP and RAMP-primed macrophages, depending on the predominant subpopulation, regulate the balance between inflammatory and resolving processes. While sterile injury and pathogen-induced reactions may have distinct effects on macrophages, most studies have focused on macrophage responses induced by pathogens. In this review, which emphasizes available human data, we illustrate how macrophages sense these mediators by examining the expression of receptors for DAMPs, RAMPs, and SPMs. We also delve into the signaling pathways induced by DAMPs, RAMPs, and SPMs, which primarily contribute to the regulation of macrophage differentiation from a pro-inflammatory to a pro-resolution phenotype. Understanding the regulatory mechanisms behind the transition between macrophage subtypes can offer insights into manipulating the transition from inflammation to resolution in sterile inflammatory diseases.

Relationship between calcium dynamics and inflammatory status in the transition period of dairy cows

Improvements in nutrition, management, and genetics of dairy cows over the last several decades have shifted research focus from clinical diseases to subclinical disorders, to which transition cows are particularly vulnerable. Recent studies on the characterization of subclinical hypocalcemia (SCH) indicate that the combined analysis of the degree, timing of suboptimal blood Ca concentration, and duration are most reflective of the disorder. Therefore, the understanding of blood Ca dynamics in early postpartum cows has emerged as an avenue to investigate the paths leading to a successful metabolic adaptation to lactation or not. The conundrum has been in defining whether SCH is the cause or a reflection of a greater underlying disorder. Immune activation and systemic inflammation have been proposed to be the root cause of SCH. However, there is a paucity of data investigating the mechanisms of how systemic inflammation can lead to reduced blood Ca concentration in dairy cows. The objective of this review is to discuss the links between systemic inflammation and reduced blood Ca concentration, and studies needed to advance knowledge on the interface between systemic inflammation and Ca metabolism for the transition dairy cow.

Inflammation, Mitochondria and Natural Compounds Together in the Circle of Trust

Human diseases are characterized by the perpetuation of an inflammatory condition in which the levels of Reactive Oxygen Species (ROS) are quite high. Excessive ROS production leads to DNA damage, protein carbonylation and lipid peroxidation, conditions that lead to a worsening of inflammatory disorders. In particular, compromised mitochondria sustain a stressful condition in the cell, such that mitochondrial dysfunctions become pathogenic, causing human disorders related to inflammatory reactions. Indeed, the triggered inflammation loses its beneficial properties and turns harmful if dysregulation and dysfunctions are not addressed. Thus, reducing oxidative stress with ROS scavenger compounds has proven to be a successful approach to reducing inflammation. Among these, natural compounds, in particular, polyphenols, alkaloids and coenzyme Q₁₀, thanks to their antioxidant properties, are capable of inhibiting the activation of NF-κB and the expression of target genes, including those involved in inflammation. Even more, clinical trials, and in vivo and in vitro studies have demonstrated the antioxidant and anti-inflammatory effects of phytosomes, which are capable of increasing the bioavailability and effectiveness of natural compounds, and have long been considered an effective non-pharmacological therapy. Therefore, in this review, we wanted to highlight the relationship between inflammation, altered mitochondrial oxidative activity in pathological conditions, and the beneficial effects of phytosomes. To this end, a PubMed literature search was conducted with a focus on various in vitro and in vivo studies and clinical trials from 2014 to 2022.

Amnion-derived serum amyloid A1 participates in sterile inflammation of fetal membranes at parturition

OBJECTIVES

Sterile inflammation of fetal membranes is an indispensable event of normal parturition. However, triggers of sterile inflammation are not fully resolved. Serum amyloid A1 (SAA1) is an acute phase protein produced primarily by the liver. Fetal membranes can also synthesize SAA1 but its functions are not well defined. Given the role of SAA1 in the acute phase response to inflammation, we postulated that SAA1 synthesized in the fetal membranes may be a trigger of local inflammation at parturition.

METHODS

The changes of SAA1 abundance in parturition were studied in the amnion of human fetal membranes. The role of SAA1 in chemokine expression and leukocyte chemotaxis was examined in cultured human amnion tissue explants as well as primary human amnion fibroblasts. The effects of SAA1 on monocytes, macrophages and dendritic cells were investigated in cells derived from a human leukemia monocytic cell line (THP-1).

RESULTS

SAA1 synthesis increased significantly in human amnion at parturition. SAA1 evoked multiple chemotaxis pathways in human amnion fibroblasts along with upregulation of a series of chemokines via both toll-like receptor 4 (TLR4) and formyl peptide receptor 2 (FPR2). Moreover, SAA1-conditioned medium of cultured amnion fibroblasts was capable of chemoattracting virtually all types of mononuclear leukocytes, particularly monocytes and dendritic cells, which reconciled with the chemotactic activity of conditioned medium of cultured amnion tissue explants collected from spontaneous labor. Furthermore, SAA1 could induce the expression of genes associated with inflammation and extracellular matrix remodeling in monocytes, macrophages and dendritic cells derived from THP-1.

CONCLUSIONS

SAA1 is a trigger of sterile inflammation of the fetal membranes at parturition.

Effectiveness of targeting the NLRP3 inflammasome by using natural polyphenols: A systematic review of implications on health effects

Globally, inflammation and metabolic disorders pose serious public health problems and are major health concerns. It has been shown that natural polyphenols are effective in the treatment of metabolic diseases, including anti-inflammation, anti-diabetes, anti-obesity, neuron-protection, and cardio-protection. NLRP3 inflammasome, which are multiprotein complexes located within the cytosol, play an important role in the innate immune system. However, aberrant activation of the NLRP3 inflammasome were discovered as essential molecular mechanisms in triggering inflammatory processes as well as implicating it in several major metabolic diseases, such as type 2 diabetes mellitus, obesity, atherosclerosis or cardiovascular disease. Recent studies indicate that natural polyphenols can inhibit NLRP3 inflammasome activation. In this review, the progress of natural polyphenols preventing inflammation and metabolic disorders via targeting NLRP3 inflammasome is systemically summarized. From the viewpoint of interfering NLRP3 inflammasome activation, the health effects of natural polyphenols are explained. Recent advances in other beneficial effects, clinical trials, and nano-delivery systems for targeting NLRP3 inflammasome are also reviewed. NLRP3 inflammasome is targeted by natural polyphenols to exert multiple health effects, which broadens the understanding of polyphenol mechanisms and provides valuable guidance to new researchers in this field.

Interaction Between Adipocytes and B Lymphocytes in Human Metabolic Diseases

Diseases associated with the disorders of carbohydrate and lipid metabolism are widespread in the modern world. Interaction between the cells of adipose tissue - adipocytes - and immune system cells is an essential factor in pathogenesis of such diseases. Long-term increase in the glucose and fatty acid levels leads to adipocyte hypertrophy and increased expression of pro-inflammatory cytokines and adipokines by these cells. As a result, immune cells acquire a pro-inflammatory phenotype, and new leukocytes are recruited. Inflammation of adipose tissue leads to insulin resistance and stimulates formation of atherosclerotic plaques and development of autoimmunity. New studies show that different groups of B lymphocytes play an essential role in regulation of adipose tissue inflammation. Decrease in the number of B-2 lymphocytes suppresses development of a number of metabolic diseases, whereas decreased numbers of the regulatory B lymphocytes and B-1 lymphocytes are associated with more severe pathology. Recent studies showed that adipocytes influence B lymphocyte activity both directly and by altering activity of other immune cells. These findings provide better understanding of the molecular mechanisms of human pathologies associated with impaired carbohydrate and lipid metabolism, such as type 2 diabetes mellitus.

Solid lipid nanoparticles (SLNs), the potential novel vehicle for enhanced in vivo efficacy of hesperidin as an anti-inflammatory agent

Hesperidin (C₂₈H₃₄O₁₅), a flavanone glycoside abundantly present in citrus fruits, has proven therapeutic effects including anti-inflammatory activities. Herein, we report a novel formulation of HESP loaded solid lipid nanoparticles (SLNs) using hot homogenization and ultrasound to improve the poor solubility and bioavailability. In the present study, the formulation was developed and optimized by response surface method and then characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy (FT-IR), and dynamic light scattering (DLS). Encapsulation efficiency was determined and the anti-inflammatory effect was assessed through in vivo ear edema inflammation model. According to the electron microscopy results, the product has a spherical shape. The optimized parameters produced small size (179.8 ± 3.6 nm) HESP-SLNs with high encapsulation efficiency (93.0 ± 3.8 %). The outcomes exhibited that encapsulation in SLNs carriers improves the anti-inflammatory potential of HESP.

Phenotypic and functional characterisation of synovial fluid-derived neutrophils in knee osteoarthritis and knee infection

OBJECTIVE

An increase in the number of neutrophils (NEUs) has long been associated with infections in the knee joints; however, their impact on knee osteoarthritis (KOA) pathophysiology remains largely unexplored.

DESIGN

This study compared the phenotypic and functional characteristics of synovial fluid (SF)-derived NEUs in KOA and knee infection (INF).

RESULTS

KOA NEUs were characterised by a lower expression of CD11b, CD54, and CD64 and higher expression of CD62L, TLR2, and TLR4 compared with INF NEUs. Except for CCL2, lower levels of inflammatory mediators and proteases were detected in KOA SF than in INF SF. Functionally, KOA NEUs displayed increased reactive oxygen species production and phagocytic activity compared with INF NEUs. Moreover, KOA and INF NEUs differed in cell sizes, histological characteristics of the surrounding synovial tissues, and their effects on the endothelial cells assessed by human umbilical vein endothelial cells. When KOA patients were subdivided based on the SF NEU abundance, patients with high NEUs (10%-60%) were characterised by i) elevated SF protein levels of TNF-α, IL-1RA, MMP-9, sTREM-1, VILIP-1 and ii) lower CD54, CD64, TLR2 and TLR4 expression compared to patients with low NEUs (<10%). Analysis of paired SF samples suggests that low or high NEU percentages, respectively, persist throughout the course of disease.

CONCLUSIONS

Our findings suggest that NEU may play a significant role in KOA pathophysiology. Further studies should explore the mechanisms that contribute to the increased number of NEUs in SF and the clinical consequences of neutrophilic phenotype in KOA.

What Exactly Is Inflammation (and What Is It Not?)

In medicine, inflammation is a fuzzy, overused word first coined by the Romans, the intended meaning and precise definition of which varies according to the person and the clinical context. It tends to carry a negative connotation as a response gone awry, like a raging, out-of-control wildfire that requires immediate control and containment lest it destroy all in its path; however, frequently overlooked or lost in the shuffle is the primordial importance of inflammation to health and survival. The precise definition of inflammation matters for several reasons, not least because of the over-liberal use of anti-inflammatory drugs to inhibit inflammation, which may, contrary to prevailing dogma that all inflammation is harmful, act counterproductively to prevent restitutio ad integrum. Using fire as a central analogy, this overview attempts to define inflammation, the better to determine how to manage it, i.e., whether to fan its flames, let it burn out, or suppress it entirely.

Plasma protein biomarkers for primary graft dysfunction after lung transplantation: a single-center cohort analysis

The clinical use of circulating biomarkers for primary graft dysfunction (PGD) after lung transplantation has been limited. In a prospective single-center cohort, we examined the use of plasma protein biomarkers as indicators of PGD severity and duration after lung transplantation. The study comprised 40 consecutive lung transplant patients who consented to blood sample collection immediately pretransplant and at 6, 24, 48, and 72 h after lung transplant. An expert grader determined the severity and duration of PGD and scored PGD at T0 (6 h after reperfusion), T24, T48, and T72 h post-reperfusion using the 2016 ISHLT consensus guidelines. A bead-based multiplex assay was used to measure 27 plasma proteins including cytokines, growth factors, and chemokines. Enzyme-linked immunoassay was used to measure cell injury markers including M30, M65, soluble receptor of advanced glycation end-products (sRAGE), and plasminogen activator inhibitor-1 (PAI-1). A pairwise comparisons analysis was used to assess differences in protein levels between PGD severity scores (1, 2, and 3) at T0, T24, T48, and T72 h. Sensitivity and temporal analyses were used to explore the association of protein expression patterns and PGD3 at T48-72 h (the most severe, persistent form of PGD). We used the Benjamini-Hochberg method to adjust for multiple testing. Of the 40 patients, 22 (55%) had PGD3 at some point post-transplant from T0 to T72 h; 12 (30%) had PGD3 at T48-72 h. In the pairwise comparison, we identified a robust plasma protein expression signature for PGD severity. In the sensitivity analysis, using a linear model for microarray data, we found that differential perioperative expression of IP-10, MIP1B, RANTES, IL-8, IL-1Ra, G-CSF, and PDGF-BB correlated with PGD3 development at T48-72 h (FDR < 0.1 and p < 0.05). In the temporal analysis, using linear mixed modeling with overlap weighting, we identified unique protein patterns in patients who did or did not develop PGD3 at T48-72 h. Our findings suggest that unique inflammatory protein expression patterns may be informative of PGD severity and duration. PGD biomarker panels may improve early detection of PGD, predict its clinical course, and help monitor treatment efficacy in the current era of lung transplantation.

A simple model of COVID-19 explains disease severity and the effect of treatments

Considerable effort has been made to better understand why some people suffer from severe COVID-19 while others remain asymptomatic. This has led to important clinical findings; people with severe COVID-19 generally experience persistently high levels of inflammation, slower viral load decay, display a dysregulated type-I interferon response, have less active natural killer cells and increased levels of neutrophil extracellular traps. How these findings are connected to the pathogenesis of COVID-19 remains unclear. We propose a mathematical model that sheds light on this issue by focusing on cells that trigger inflammation through molecular patterns: infected cells carrying pathogen-associated molecular patterns (PAMPs) and damaged cells producing damage-associated molecular patterns (DAMPs). The former signals the presence of pathogens while the latter signals danger such as hypoxia or lack of nutrients. Analyses show that SARS-CoV-2 infections can lead to a self-perpetuating feedback loop between DAMP expressing cells and inflammation, identifying the inability to quickly clear PAMPs and DAMPs as the main contributor to hyperinflammation. The model explains clinical findings and reveal conditions that can increase the likelihood of desired clinical outcome from treatment administration. In particular, the analysis suggest that antivirals need to be administered early during infection to have an impact on disease severity. The simplicity of the model and its high level of consistency with clinical findings motivate its use for the formulation of new treatment strategies.

Histopathological characteristics of larynx in hypothyroidism in an experimental rabbit model

Objective

Hypothyroidism has a significant effect on the patients' voices. This study evaluated the histopathological characteristics of larynx following hypothyroidism in an experimental rabbit model.

Methods

Eleven male Dutch rabbits were included. Methimazole-induced hypothyroidism was done for nine rabbits. The remaining two rabbits were assigned as controls. Six weeks after starting methimazole, a histological examination was performed with parameters of inflammation, ulceration, hemorrhage, and thickness of epithelium, Reinke's space, vocal ligament, thyroarytenoid muscle, collagen deposition, and periodic acid-Schiff (PAS)-positive materials, as well as confirmation of hypothyroidism by T4 measurement.

Results

Histologic examination showed a significant thickening of epithelium, Reinke's space, vocal ligament, and collagen PAS-positive materials deposition in hypothyroid rabbits (p < .05). There was significant reduction in thyroarytenid muscle thickness (p < .05). Inflammation, ulceration, and bleeding were not significantly different between hypothyroid and control rabbits' laryngeal specimens.

Conclusion

Hypothyroidism causes significant changes in the laryngeal tissues. Thickening of epithelium, Reinke's space, vocal ligament, collagen, PAS-positive materials, and reduced thickness of thyroarytenoid muscle are the major findings of this study.

Isolation and Characterization of Efficient Active Compounds Using High-Performance Centrifugal Partition Chromatography (CPC) from Anti-Inflammatory Activity Fraction of Ecklonia maxima in South Africa

Ecklonia maxima is a brown seaweed, which is abundantly distributed in South Africa. This study investigated an efficient approach using high-performance centrifugal partition chromatography (HPCPC), which has been successfully developed for the isolation and purification of phlorotannins, eckmaxol, and dieckol from the ethyl acetate fraction of E. maxima (EEM). We evaluated EEM for its inhibitory effect against lipopolysaccharide (LPS)-induced inflammatory responses in zebrafish embryos. The separation of eckmaxol and dieckol from samples of EEM using HPCPC was found to be of high purity and yield under an optimal solvent system composed of n-hexane:ethyl acetate:methanol:water (2:7:3:7, v/v/v/v). To evaluate the anti-inflammatory efficacy of EEM containing active compounds, zebrafish embryos exposed to LPS were compared with and without EEM treatment for nitric oxide (NO) production, reactive oxygen species (ROS) generation, and cell death two days after fertilization. These evaluations indicate that EEM alleviated inflammation by inhibiting cell death, ROS, and NO generation induced by LPS treatment. According to these results, eckmaxol and dieckol isolated from brown seaweed E. maxima could be considered effective anti-inflammatory agents as pharmaceutical and functional food ingredients.

Specialized Proresolving Lipid Meditators Agonistic to Formyl Peptide Receptor Type 2 Attenuate Ischemia-reperfusion Injury in Rat Lung

BACKGROUND

Lung ischemia-reperfusion injury (IRI) is a form of acute lung injury characterized by nonspecific alveolar damage and lung edema due to robust inflammation. Little is known about the roles of specialized proresolving lipid mediators (SPMs) in lung IRI. Therefore, we aimed to evaluate the dynamic changes in endogenous SPMs during the initiation and resolution of lung IRI and to determine the effects of SPM supplementation on lung IRI.

METHODS

We used a rat left hilar clamp model with 90 min of ischemia, followed by reperfusion. Dynamic changes in endogenous SPMs were evaluated using liquid chromatography-tandem mass spectrometry.

RESULTS

Endogenous SPMs in the left lung showed a decreasing trend after 1 h of reperfusion. Oxygenation improved between 3 and 7 d following reperfusion; however, the level of endogenous SPMs remained low compared with that in the naïve lung. Among SPM receptors, only formyl peptide receptor type 2 (ALX/FPR2) gene expression in the left lung was increased 3 h after reperfusion, and the inflammatory cells were immunohistochemically positive for ALX/FPR2. Administration of aspirin-triggered (AT) resolvin D1 (AT-RvD1) and AT lipoxin A4 (AT-LXA4), which are agonistic to ALX/FPR2, immediately after reperfusion improved lung function, reduced inflammatory cytokine levels, attenuated lung edema, and decreased neutrophil infiltration 3 h after reperfusion. The effects of AT-RvD1 and AT-LXA4 were not observed after pretreatment with the ALX/FPR2 antagonist.

CONCLUSIONS

The level of intrapulmonary endogenous SPMs decreased during lung IRI process and the administration of AT-RvD1 and AT-LXA4 prevented the exacerbation of lung injury via ALX/FPR2.

Review of immunological plasma markers for longitudinal analysis of inflammation and infection in rat models

Disease or trauma of orthopedic tissues, including osteomyelitis, osteoporosis, arthritis, and fracture, results in a complex immune response, leading to a change in the concentration and milieu of immunological cells and proteins in the blood. While C-reactive protein levels and white blood cell counts are used to track inflammation and infection clinically, controlled longitudinal studies of disease/injury progression are limited. Thus, the use of clinically-relevant animal models can enable a more in-depth understanding of disease/injury progression and treatment efficacy. Though longitudinal tracking of immunological markers has been performed in rat models of various inflammatory and infectious diseases, currently there is no consensus on which markers are sensitive and reliable for tracking levels of inflammation and/or infection. Here, we discuss the blood markers that are most consistent with other outcome measures of the immune response in the rat, by reviewing their utility for longitudinal tracking of infection and/or inflammation in the following types of models: localized inflammation/arthritis, injury, infection, and injury + infection. While cytokines and acute phase proteins such as haptoglobin, fibrinogen, and α₂ -macroglobulin demonstrate utility for tracking immunological response in many inflammation and infection models, there is likely not a singular superior marker for all rat models. Instead, longitudinal characterization of these models may benefit from evaluation of a collection of cytokines and/or acute phase proteins. Identification of immunological plasma markers indicative of the progression of a pathology will allow for the refinement of animal models for understanding, diagnosing, and treating inflammatory and infectious diseases of orthopedic tissues.

Flavonoids in Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is a progressive systemic disease, which changes the function and structure of the kidneys irreversibly over months or years. The final common pathological manifestation of chronic kidney disease is renal fibrosis and is characterized by glomerulosclerosis, tubular atrophy, and interstitial fibrosis. In recent years, numerous studies have reported the therapeutic benefits of natural products against modern diseases. Substantial attention has been focused on the biological role of polyphenols, in particular flavonoids, presenting broadly in plants and diets, referring to thousands of plant compounds with a common basic structure. Evidence-based pharmacological data have shown that flavonoids play an important role in preventing and managing CKD and renal fibrosis. These compounds can prevent renal dysfunction and improve renal function by blocking or suppressing deleterious pathways such as oxidative stress and inflammation. In this review, we summarize the function and beneficial properties of common flavonoids for the treatment of CKD and the relative risk factors of CKD.

AMP5A modulates Toll-like receptors 7 and 8 single-stranded RNA immune responses in PMA-differentiated THP-1 and PBMC

BACKGROUND

Dysregulation of antiviral immunity has been implicated in the progression of acute respiratory syndrome coronavirus 2 infection into severe cases of coronavirus disease of 2019 (COVID-19). Imbalances in the inflammatory response drive the overabundant production of pro-inflammatory cytokines and chemokines. The low molecular weight fraction of 5% human serum albumin commercial preparation (AMP5A) is a novel biologic drug currently under clinical investigation for the treatment of osteoarthritis and the hyperinflammatory response associated with COVID-19. This study aims to elucidate AMP5A effects following the activation of immune cells with agonists of Toll-like receptor (TLR) 7 and/or 8, which detect ssRNA viral sequences.

METHODS

CXCL10 ELISAs were used to evaluate the dynamics of myeloid cells activated with CL075 and CL307, agonists of TLR7/8 and TLR7, respectively. In addition, enrichment analysis of gene sets generated by ELISA arrays was utilized to gain insight into the biologic processes underlying the identified differentially expressed cytokine profiles. Finally, relative potency (REP) was employed to confirm the involvement of mechanisms of action paramount to AMP5A activity.

RESULTS

AMP5A inhibits the release of CXCL10 from both CL075- and CL307-activated PMA-differentiated THP-1 and peripheral blood mononuclear cells. Furthermore, AMP5A suppresses a distinct set of pro-inflammatory cytokines (including IL-1β, IL-6, IL-12, and CXCL10) associated with COVID-19 and pro-inflammatory NF-κB activation. REP experiments using antagonists specific for the immunomodulatory transcription factors, peroxisome proliferator-activated receptor γ, and aryl hydrocarbon receptor, also indicate that these pathways are involved in the ability of AMP5A to inhibit CXCL10 release.

CONCLUSION

Due to the biphasic course of COVID-19, therapeutic approaches that augment antiviral immunity may be more beneficial early in infection, whereas later interventions should focus on inflammation suppression. In this study, we show that AMP5A inhibits TLR 7/8 signaling in myeloid cells, resulting in a decrease in inflammatory mediators associated with hyperinflammation and autoimmunity. Furthermore, data demonstrating that AMP5A activates immunomodulatory transcription factors found to be protective in lung disease is provided. These findings suggest that the modes and mechanisms of action of AMP5A are well suited to treat conditions involving dysregulated TLR 7/8 activation.

Macrophages in Transplantation: A Matter of Plasticity, Polarization, and Diversity

Macrophages have emerged at the forefront of research in immunology and transplantation because of recent advances in basic science. New findings have illuminated macrophage populations not identified previously, expanded upon traditional macrophage phenotypes, and overhauled macrophage ontogeny. These advances have major implications for the field of transplant immunology. Macrophages are known to prime adaptive immune responses, perpetuate T-cell-mediated rejection and antibody-mediated rejection, and promote allograft fibrosis. In this review, macrophage phenotypes and their role in allograft injury of solid organ transplants will be discussed with an emphasis on kidney transplantation. Additionally, consideration will be given to the prospect of manipulating macrophage phenotypes as cell-based therapy. Innate immunity and macrophages represent important players in allograft injury and a promising target to improve transplant outcomes.

The genetic deletion of the Dual Specificity Phosphatase 3 (DUSP3) attenuates kidney damage and inflammation following ischaemia/reperfusion injury in mouse

AIM

Dual Specificity Phosphatase 3 (DUSP3) regulates the innate immune response, with a putative role in angiogenesis. Modulating inflammation and perfusion contributes to renal conditioning against ischaemia/reperfusion (I/R). We postulate that the functional loss of DUSP3 is associated with kidney resistance to I/R.

METHODS

Ten C57BL/6 male WT and Dusp3^-/- mice underwent right nephrectomy and left renal I/R (30 min/48 hours). Renal injury was assessed based on serum levels of urea (BUN) and Jablonski score. The expression of CD31 and VEGF vascular markers was quantified by RT-qPCR and immuno-staining. Renal resistivity index (RRI) was measured in vivo by Doppler ultrasound. Comparative phosphoproteomics was conducted using IMAC enrichment of phosphopeptides. Inflammatory markers were quantified at both mRNA and protein levels in ischaemic vs non-ischaemic kidneys in WT vs Dusp3^-/- .

RESULTS

At baseline, we located DUSP3 in renal glomeruli and endothelial cells. CD31-positive vascular network was significantly larger in Dusp3^-/- kidneys compared to WT, with a lower RRI in Dusp3^-/- mice. Following I/R, BUN and Jablonski score were significantly lower in Dusp3^-/- vs WT mice. Phosphoproteomics highlighted a down-regulation of inflammatory pathways and up-regulation of phospho-sites involved in cell metabolism and VEGF-related angiogenesis in Dusp3^-/- vs WT ischaemic kidneys. Dusp3^-/- ischaemic kidneys showed decreased mRNA levels of CD11b, TNF-α, KIM-1, IL-6, IL-1β and caspase-3 compared to controls. The numbers of PCNA-, F4-80- and CD11b-positive cells were reduced in Dusp3^-/- vs WT kidneys post-I/R.

CONCLUSION

Genetic inactivation of Dusp3 is associated with kidney conditioning against I/R, possibly due to attenuated inflammation and improved perfusion.

Biomaterials-Driven Sterile Inflammation

Performance of the biomaterials used for regenerative medicine largely depends on biocompatibility; however, the biological mechanisms underlying biocompatibility of a biomaterial within the host system is poorly understood. In addition to the classical immune response against non-self-entities, the sterile inflammatory response could limit the compatibility of biological scaffolds. Whereas the immediate to short-term host response to a biomaterial implant have been characterized, the long-term progression of host-biomaterial relationship has not been described. This article explores the novel concept of biomaterials-driven sterile inflammation (BSI) in long-term biodegradable implants and throws light for possible explanation for the onset of BSI and the associated damage-associated molecular patterns. The understanding of BSI would advance the current strategies to improve biomaterial-host tissue integration and open novel translational avenues in biomaterials-based tissue regeneration. Impact statement Understanding the novel concept of biomaterials-driven sterile inflammation and associated damage-associated molecular patterns in long-term biodegradable implants would determine their success and improves the tissue engineering and regenerative strategies.

Interventional study with vitamin E in cardiovascular disease and meta-analysis

Cardiovascular disease (CVD) is one of the major causes of morbidity and mortality and atherosclerosis is the common root to most of the CVD. Oxidative stress is one of the most important factors driving atherosclerosis and its complications. Thus, strategies for the prevention and treatment of cardiovascular events had oxidative changes as a potential target. Natural vitamin E consists of a family of eight different compounds, four tocopherols and four tocotrienols. All tocopherols and tocotrienols are potent antioxidants with lipoperoxyl radical-scavenging activities. In addition, α-tocopherol possesses also anti-inflammatory as well as anti-atherothrombotic effects by modulating platelet and clotting system. Experimental and in vitro studies described molecular and cellular signalling pathways regulated by vitamin E antithrombotic and antioxidant properties. While observational studies demonstrated an inverse association between vitamin E serum levels and CVD, interventional trials with vitamin supplements provided negative results. This review focus on the impact of vitamin E in the atherothrombotic process and describes the results of experimental and clinical studies with the caveats related to the interventional trials with vitamin E to prevent CVD.

Promotion of trained innate immunity by nanoparticles

The dogma that immunological memory is an exclusive trait of adaptive immunity has been recently challenged by studies showing that priming of innate cells can also result in modified long-term responsiveness to secondary stimuli, once the cells have returned to a non-activated state. This phenomenon is known as 'innate immune memory', 'trained immunity' or 'innate training'. While the main known triggers of trained immunity are microbial-derived molecules such as β-glucan, endogenous particles such as oxidized low-density lipoprotein and monosodium urate crystals can also induce trained phenotypes in innate cells. Whether exogenous particles can induce trained immunity has been overlooked. Our exposure to particulates has dramatically increased in recent decades as a result of the broad medical use of particle-based drug carriers, theragnostics, adjuvants, prosthetics and an increase in environmental pollution. We recently showed that pristine graphene can induce trained immunity in macrophages, enhancing their inflammatory response to TLR agonists, proving that exogenous nanomaterials can affect the long-term response of innate cells. The consequences of trained immunity can be beneficial, for instance, enhancing protection against unrelated pathogens; however, they can also be deleterious if they enhance inflammatory disorders. Therefore, studying the ability of particulates and biomaterials to induce innate trained phenotypes in cells is warranted. Here we analyse the mechanisms whereby particles can induce trained immunity and discuss how physicochemical characteristics of particulates could influence the induction of innate memory. We review the implications of trained immunity in the context of particulate adjuvants, nanocarriers and nanovaccines and their potential applications in medicine. Finally, we reflect on the unanswered questions and the future of the field.

Podocyte Aging: Why and How Getting Old Matters

The effects of healthy aging on the kidney, and how these effects intersect with superimposed diseases, are highly relevant in the context of the population's increasing longevity. Age-associated changes to podocytes, which are terminally differentiated glomerular epithelial cells, adversely affect kidney health. This review discusses the molecular and cellular mechanisms underlying podocyte aging, how these mechanisms might be augmented by disease in the aged kidney, and approaches to mitigate progressive damage to podocytes. Furthermore, we address how biologic pathways such as those associated with cellular growth confound aging in humans and rodents.

Protective effects of anti-HMGB1 monoclonal antibody on lung ischemia reperfusion injury in mice

During ischemia reperfusion (IR) injury, high mobility group box 1 (HMGB1), a chromatin binding protein, is released from necrotic cells and triggers inflammatory responses. We assessed the therapeutic effect of a neutralizing anti-HMGB1 monoclonal antibody (mAb) on lung IR injury. A murine hilar clamp model of IR was used, where mice were divided into sham and IR groups with intravenous administration of anti-HMGB 1 mAb or control mAb. We analyzed the effect of anti-HMGB1 mAb against IR injury by assessing lung oxygenation, lung injury score, neutrophil infiltration, expression of proinflammatory cytokines and chemokines, levels of mitogen-activated protein kinase (MAPK) signaling, and measurement of apoptotic cells. Anti-HMGB1 mAb significantly decreased the plasma level of HMGB1 elevated by IR. The severity of IR injury represented by oxygenation capacity, lung injury score, and neutrophil infiltration was significantly improved by anti-HMGB1 mAb treatment. The expression of proinflammatory factors, including IL-1β, IL-6, IL-12, TNF-α, CXCL-1, and CXCL-2, and phosphorylation of p38 MAPK were both significantly reduced by anti-HMGB1 mAb treatment. Furthermore, anti-HMGB1 mAb treatment suppressed apoptosis, as determined through TUNEL assays. Overall, anti-HMGB1 mAb ameliorated lung IR injury by reducing inflammatory responses and apoptosis. Our findings indicate that anti-HMGB1 mAb has potential for use as a therapeutic to improve IR injury symptoms during lung transplantation.

Microglia and BDNF at the crossroads of stressor related disorders: Towards a unique trophic phenotype

Stressors ranging from psychogenic/social to neurogenic/injury to systemic/microbial can impact microglial inflammatory processes, but less is known regarding their effects on trophic properties of microglia. Recent studies do suggest that microglia can modulate neuronal plasticity, possibly through brain derived neurotrophic factor (BDNF). This is particularly important given the link between BDNF and neuropsychiatric and neurodegenerative pathology. We posit that certain activated states of microglia play a role in maintaining the delicate balance of BDNF release onto neuronal synapses. This focused review will address how different "activators" influence the expression and release of microglial BDNF and address the question of tropomyosin receptor kinase B (TrkB) expression on microglia. We will then assess sex-based differences in microglial function and BDNF expression, and how microglia are involved in the stress response and related disorders such as depression. Drawing on research from a variety of other disorders, we will highlight challenges and opportunities for modulators that can shift microglia to a "trophic" phenotype with a view to potential therapeutics relevant for stressor-related disorders.

Role of albumin on endothelial basement membrane and hemostasis in a rat model of hemorrhagic shock

BACKGROUND

We sought to determine the extent of loss of endothelial basement membrane (BM), leukocyte recruitment, and changes in coagulation after hemorrhagic shock, followed by limited-volume resuscitation (LVR) with 5% albumin (ALB).

METHODS

Anesthetized rats were bled 40% of blood volume and assigned to treatment groups: untreated (n = 6), LVR with normal saline (NS; n = 8), or LVR with ALB (n = 8). Sham rats (n = 6) underwent all procedures except hemorrhage or resuscitation. Blood samples were assayed for active proteases, such as metalloproteinase 9 (MMP-9) and a disintegrin and metalloproteinase 10 (ADAM-10), BM-type heparan sulfate proteoglycan (perlecan), cell count, and coagulation function. Leukocyte transmigration was used to estimate the net efficiency of leukocyte recruitment in cremaster venules.

RESULTS

Hemorrhage significantly lowered red cell count, but white cell and platelet counts did not change (vs. sham). Ionized calcium in plasma was significantly reduced in untreated and remained so after NS. In contrast, ionized calcium was normalized after ALB. Plasma expansion after NS and ALB further reduced leukocyte and platelet counts. Metalloproteinase 9, ADAM-10, and perlecan were significantly higher in untreated rats (vs. sham). Albumin normalized MMP-9, ADAM-10, and perlecan levels, while NS further increased MMP-9, ADAM-10, and perlecan (vs. sham). Transmigrated leukocytes doubled in the untreated group and remained elevated after NS (vs. sham) but normalized after ALB. Albumin reduced every stage of the leukocyte recruitment process to sham levels.

CONCLUSION

Despite similar plasma expansion, NS weakened platelet function contrary to ALB. Plasma expansion with ALB resulted in restoration of BM integrity and attenuation of leukocyte recruitment to tissues, in contrast to NS. Albumin plays a critical role in restoring BM integrity, attenuating leukocyte recruitment to tissues, and optimizing hemostasis by increasing ionized calcium in plasma.

Suppressing Pyroptosis Augments Post-Transplant Survival of Stem Cells and Cardiac Function Following Ischemic Injury

The acute demise of stem cells following transplantation significantly compromises the efficacy of stem cell-based cell therapeutics for infarcted hearts. As the stem cells transplanted into the damaged heart are readily exposed to the hostile environment, it can be assumed that the acute death of the transplanted stem cells is also inflicted by the same environmental cues that caused massive death of the host cardiac cells. Pyroptosis, a highly inflammatory form of programmed cell death, has been added to the list of important cell death mechanisms in the damaged heart. However, unlike the well-established cell death mechanisms such as necrosis or apoptosis, the exact role and significance of pyroptosis in the acute death of transplanted stem cells have not been explored in depth. In the present study, we found that M1 macrophages mediate the pyroptosis in the ischemia/reperfusion (I/R) injured hearts and identified miRNA-762 as an important regulator of interleukin 1β production and subsequent pyroptosis. Delivery of exogenous miRNA-762 prior to transplantation significantly increased the post-transplant survival of stem cells and also significantly ameliorated cardiac fibrosis and heart functions following I/R injury. Our data strongly suggest that suppressing pyroptosis can be an effective adjuvant strategy to enhance the efficacy of stem cell-based therapeutics for diseased hearts.

Hypoxia-inducible factor-dependent induction of myeloid-derived netrin-1 attenuates natural killer cell infiltration during endotoxin-induced lung injury

Sepsis and sepsis‐associated lung inflammation significantly contribute to the morbidity and mortality of critical illness. Here, we examined the hypothesis that neuronal guidance proteins could orchestrate inflammatory events during endotoxin‐induced lung injury. Through a targeted array, we identified netrin‐1 as the top upregulated neuronal guidance protein in macrophages treated with lipopolysaccharide (LPS). Furthermore, we found that netrin‐1 is highly enriched in infiltrating myeloid cells, particularly in macrophages during LPS‐induced lung injury. Transcriptional studies implicate hypoxia‐inducible factor HIF‐1α in the transcriptional induction of netrin‐1 during LPS treatment. Subsequently, the deletion of netrin‐1 in the myeloid compartment (Ntn1^loxp/loxp LysM Cre) resulted in exaggerated mortality and lung inflammation. Surprisingly, further studies revealed enhanced natural killer cells (NK cells) infiltration in Ntn1^loxp/loxp LysM Cre mice, and neutralization of NK cell chemoattractant chemokine (C‐C motif) ligand 2 (CCL2) reversed the exaggerated lung inflammation. Together, these studies provide functional insight into myeloid cell‐derived netrin‐1 in controlling lung inflammation through the modulation of CCL2‐dependent infiltration of NK cells.

The Role of Macrophages During Mammalian Tissue Remodeling and Regeneration Under Infectious and Non-Infectious Conditions

Several infectious pathologies in humans, such as tuberculosis or SARS-CoV-2, are responsible for tissue or lung damage, requiring regeneration. The regenerative capacity of adult mammals is limited to few organs. Critical injuries of non-regenerative organs trigger a repair process that leads to a definitive architectural and functional disruption, while superficial wounds result in scar formation. Tissue lesions in mammals, commonly studied under non-infectious conditions, trigger cell death at the site of the injury, as well as the production of danger signals favouring the massive recruitment of immune cells, particularly macrophages. Macrophages are also of paramount importance in infected injuries, characterized by the presence of pathogenic microorganisms, where they must respond to both infection and tissue damage. In this review, we compare the processes implicated in the tissue repair of non-infected versus infected injuries of two organs, the skeletal muscles and the lungs, focusing on the primary role of macrophages. We discuss also the negative impact of infection on the macrophage responses and the possible routes of investigation for new regenerative therapies to improve the recovery state as seen with COVID-19 patients.

Heart Donation From Donors After Controlled Circulatory Death

The gold-standard therapy for advanced-stage heart failure is cardiac transplantation. Since the first heart transplant in 1967, the majority of hearts transplanted came from brain death donors. Nevertheless, in recent years, the option of donation after circulatory death (DCD) is gaining importance to increase donor pool. Currently, heart-transplant programs using controlled donation after circulatory death (cDCD) have been implemented in the United Kingdom, Belgium, Australia, United States of America, and, recently, in Spain. In this article, we performed a concise review of the literature in heart cDCD; we summarize the pathophysiology involved in ischemia and reperfusion injury during this process, the different techniques of heart retrieval in cDCD donors, and the strategies that can be used to minimize the damage during retrieval and until transplantation. Heart transplant using DCD hearts is in continuous improvement and must be implemented in experienced cardiac transplant centers.

Dexmedetomidine post-conditioning attenuates cerebral ischemia following asphyxia cardiac arrest through down-regulation of apoptosis and neuroinflammation in rats

Background

Neuroprotection strategies after cardiac arrest (CA)/cardiopulmonary resuscitation (CPR) remain key areas of basic and clinical research. This study was designed to investigate the neuroprotective effects of dexmedetomidine following resuscitation and potential mechanisms.

Methods

Anesthetized rats underwent 6-min asphyxia-based cardiac arrest and resuscitation, after which the experimental group received a single intravenous dose of dexmedetomidine (25 μg/kg). Neurological outcomes and ataxia were assessed after the return of spontaneous circulation. The serum levels and brain expression of inflammation markers was examined, and apoptotic cells were quantified by TUNEL staining.

Results

Neuroprotection was enhanced by dexmedetomidine post-conditioning after the return of spontaneous circulation. This enhancement was characterized by the promotion of neurological function scores and coordination. In addition, dexmedetomidine post-conditioning attenuated the serum levels of the pro-inflammatory cytokine tumor necrosis factor (TNF)-α at 2 h, as well as interleukin IL-1β at 2, 24, and 48 h. TUNEL staining showed that the number of apoptotic cells in the dexmedetomidine post-conditioning group was significantly reduced compared with the control group. Further western blot analysis indicated that dexmedetomidine markedly reduced the levels of caspase-3 and nuclear factor-kappa B (NF-κB) in the brain.

Conclusions

Dexmedetomidine post-conditioning had a neuroprotective effect against cerebral injury following asphyxia-induced cardiac arrest. The mechanism was associated with the downregulation of apoptosis and neuroinflammation.

Inflammation at the Crossroads: the Combined Effects of COVID-19, Ageing, and Air Pollution

The global COVID-19 pandemic has highlighted different vulnerability profiles among individuals. With the highest mortality rate, the elderly are a very sensitive group. With regard to the main symptoms, a failure of the respiratory system, associated with deregulation of the immune system, has been observed. These symptoms may also be encountered in chronic exposure of susceptible populations to air pollution, including exacerbation of the inflammatory response. Is there a relationship between age, pollution exposure and the severity of COVID-19? Although it is unclear how these parameters are related, the same pathways can be activated and appear to find a common mechanism of action in inflammation.

Direct kidney injury or lower extremity ischemia induced indirect kidney injury: Which one is more harmful for kidneys?

OBJECTIVES

The aim of this study was to investigate and compare the severity of kidney damage following lower limb ischemia-reperfusion and direct kidney ischemia-reperfusion.

METHODS

Thirty Sprague Dawley male rats were randomly divided into three groups; lower extremity ischemia-reperfusion group (Group 2), renal ischemia-reperfusion group (Group 3) and control (anesthesia and median laparotomy only) (Group 1). In group 3, 1-h ischemia was performed on the kidney and in group 2, 1-h ischemia was performed on the left lower extremity. This procedure was followed by reperfusion for 24 h. Renal tissues were removed after the reperfusion period and the groups were evaluated for glutathioneperoxidase activity, malondialdehyde and GSH levels, and furthermore, their histolopathological scores were calculated.

RESULTS

Renal malondialdehyde levels were significantly higher in Group 2 and Group 3 than they were in the Control group. There was no significant difference in renal malondialdehyde levels between Group 2 and Group 3. Kidney glutathione (GSH) levels were statistically lower in Group 2 and Group 3 than in the Control group. No statistically significant difference was found between Group 2 and Group 3 regarding their GSH levels. In histological evaluation, there was no statistically significant difference between Group 2 and Group 3 in terms of kidney damage score.

CONCLUSIONS

This study has identified that lower extremity ischemia induces remote kidney damage with similar features to kidney injury, occurring after direct kidney ischemia-reperfusion.

Acute and Sub-Chronic Effects of Microplastics (3 and 10 µm) on the Human Intestinal Cells HT-29

Due to ingestion of contaminated foods, the human gastrointestinal tract is the most likely site of exposure to microplastics (MPs) with gut barrier dysfunction and intestinal inflammation. Aimed to assess the effects induced by MPs with different granulometry (polystyrene (PS) 3 and 10 µm), we performed an in vitro study by using the human intestinal cell line HT29. As a novelty, we assessed the sub-chronic exposure extending the treatment up to 48 days simulating the in vivo situation. In the range of 100–1600 particles mL⁻¹, both the PS suspensions had moderate cytotoxicity after 24 h with percentages of mortality between 6.7 and 21.6 for the 10 µm and 6.1 and 29.6 for the 3 µm PS. Microscopic observation highlighted a more pronounced lysosomal membrane permeabilization in HT29 exposed to PS 3µm. Reactive oxygen species production was higher in cells exposed to PS 10 µm, but sub-chronic exposure highlighted the ability of the cells to partially neutralize this effect. Comet-assay confirmed the temporary oxidative damage that was PS-induced. Overall, considering the very fast turnover of intestinal cells, the increase in cell mortality, equal to 25% and 11% for 3 and 10 µm PS-MPs for each time point, could trigger intestinal disorders due to prolonged exposure.