Aging results in accumulation of M1 and M2 hepatic macrophages and a differential response to gadolinium chloride

Deposition of Gadolinium in the Central and Peripheral Nervous Systems and Its Effects on Sensory, Cognitive, and Athletic Implications after Multiple Injections of Gadolinium-Based Contrast Agents in Rats

BACKGROUND AND PURPOSE

After repeat administration of gadolinium-based contrast agents (GBCAs), the association between gadolinium retention in the central and peripheral nervous systems and the main manifestations of myelopathy and progressive neurologic symptoms remains unclear. We investigated the effects of the repeat administration of GBCAs on gadolinium retention in the central and peripheral nervous systems and the sensory, cognitive, and athletic implications.

MATERIALS AND METHODS

Forty-eight male Wistar rats (6 weeks of age) were randomly divided into 4 experimental groups (12 rats in each group): the gadodiamide group (linear and nonionic GBCAs), the gadopentetate dimeglumine group (linear and ionic GBCAs), the gadoterate meglumine group (macrocyclic and ionic GBCAs), and the control group (0.9% saline solution). The brains of the rats were scanned using 9.4T MRI. Sensory behavioral tests were performed to assess the effect of GBCAs on pain sensitivity function. Gadolinium deposition in the brain, spinal cord, and peripheral nerves was determined by inductively coupled plasma mass-spectrometry. Transmission electron microscopy was used to observe the microscopic distribution of gadolinium after deposition in the spinal cord. The histopathologic features in the spinal cord were analyzed by H&E staining, Nissl staining, glial fibrillary acidic protein staining, and neuron-specific enolase staining after administration of GBCAs.

RESULTS

All GBCAs resulted in gadolinium deposition in the central and peripheral nerve tissues, with the highest deposition in the sciatic nerve tissue (mean, 62.86 [SD, 12.56] nmol/g). Decreased muscle power, impairment of spatial cognitive function power, and pain hypersensitivity to thermal and mechanical stimuli were observed after exposure to gadodiamide. At the spinal cord, transmission electron microscopy found that the region of gadolinium depositions had a spheric structure similar to "sea urchins" and was mainly located near the vascular basement membrane.

CONCLUSIONS

Multiple injections of GBCAs caused gadolinium deposition in the brain, spinal cord, and peripheral nerves, especially in the spinal cords of the gadodiamide group. Gadodiamide led to pain hypersensitivity and decreased muscle power and cognitive ability. For the patients who are hypersensitive to pain and need multiple MRI examinations, we recommend using macrocyclic GBCAs and the lowest dose possible.

Systematic review of the osteogenic effect of rare earth nanomaterials and the underlying mechanisms

Rare earth nanomaterials (RE NMs), which are based on rare earth elements, have emerged as remarkable biomaterials for use in bone regeneration. The effects of RE NMs on osteogenesis, such as promoting the osteogenic differentiation of mesenchymal stem cells, have been investigated. However, the contributions of the properties of RE NMs to bone regeneration and their interactions with various cell types during osteogenesis have not been reviewed. Here, we review the crucial roles of the physicochemical and biological properties of RE NMs and focus on their osteogenic mechanisms. RE NMs directly promote the proliferation, adhesion, migration, and osteogenic differentiation of mesenchymal stem cells. They also increase collagen secretion and mineralization to accelerate osteogenesis. Furthermore, RE NMs inhibit osteoclast formation and regulate the immune environment by modulating macrophages and promote angiogenesis by inducing hypoxia in endothelial cells. These effects create a microenvironment that is conducive to bone formation. This review will help researchers overcome current limitations to take full advantage of the osteogenic benefits of RE NMs and will suggest a potential approach for further osteogenesis research.

Toxicity Mechanisms of Gadolinium and Gadolinium-Based Contrast Agents-A Review

Gadolinium-based contrast agents (GBCAs) have been used for more than 30 years to improve magnetic resonance imaging, a crucial tool for medical diagnosis and treatment monitoring across multiple clinical settings. Studies have shown that exposure to GBCAs is associated with gadolinium release and tissue deposition that may cause short- and long-term toxicity in several organs, including the kidney, the main excretion organ of most GBCAs. Considering the increasing prevalence of chronic kidney disease worldwide and that most of the complications following GBCA exposure are associated with renal dysfunction, the mechanisms underlying GBCA toxicity, especially renal toxicity, are particularly important. A better understanding of the gadolinium mechanisms of toxicity may contribute to clarify the safety and/or potential risks associated with the use of GBCAs. In this work, a review of the recent literature concerning gadolinium and GBCA mechanisms of toxicity was performed.

Overview of Innate Immune Cell Landscape in Liver Aging

Aging is a biological process with a gradual decline in functional capacity, and this process often enhances the risk of chronic disease morbidity and mortality. With advanced age, the immune system undergoes a process of remodeling that can lead to a chronic inflammatory state, termed immunosenescence and inflammaging, respectively. Immunosenescence is accompanied by changes in the number, proportion, and functional capacity of the innate immune cells. The accumulation of dysfunctional immune cells and the presence of low-grade inflammation can lead to organ damage and expedite the aging process. The liver, crucial in regulating the body's metabolism and immune function, is not exempt from these effects. Age-related modifications affect its immune function and regenerative abilities, potentially increasing the prevalence of age-related liver diseases. While aging's impact on the liver is relatively less severe compared to other organ systems, it still experiences an infiltration of innate immune cells and heightened inflammation levels. This review will elaborate on how aging affects the liver's innate immune cells, such as neutrophils, macrophages, dendritic cells, mast cells, and innate lymphoid cells. It will also explore potential strategies for delaying immunosenescence to alleviate these age-related changes.

The Role of Punicalagin and Its Metabolites in Atherosclerosis and Risk Factors Associated with the Disease

Atherosclerotic cardiovascular disease (ACVD) is the leading cause of death worldwide. Although current therapies, such as statins, have led to a marked reduction in morbidity and mortality from ACVD, they are associated with considerable residual risk for the disease together with various adverse side effects. Natural compounds are generally well-tolerated; a major recent goal has been to harness their full potential in the prevention and treatment of ACVD, either alone or together with existing pharmacotherapies. Punicalagin (PC) is the main polyphenol present in pomegranates and pomegranate juice and demonstrates many beneficial actions, including anti-inflammatory, antioxidant, and anti-atherogenic properties. The objective of this review is to inform on our current understanding of the pathogenesis of ACVD and the potential mechanisms underlying the beneficial actions of PC and its metabolites in the disease, including the attenuation of dyslipidemia, oxidative stress, endothelial cell dysfunction, foam cell formation, and inflammation mediated by cytokines and immune cells together with the regulation of proliferation and migration of vascular smooth muscle cells. Some of the anti-inflammatory and antioxidant properties of PC and its metabolites are due to their strong radical-scavenging activities. PC and its metabolites also inhibit the risk factors of atherosclerosis, including hyperlipidemia, diabetes mellitus, inflammation, hypertension, obesity, and non-alcoholic fatty liver disease. Despite the promising findings that have emerged from numerous in vitro, in vivo, and clinical studies, deeper mechanistic insights and large clinical trials are required to harness the full potential of PC and its metabolites in the prevention and treatment of ACVD.

Ameliorative Effect of Citrus Lemon Peel Extract and Resveratrol on Premature Ovarian Failure Rat Model: Role of iNOS/Caspase-3 Pathway

Premature ovarian failure (POF) is described as a loss of oocytes and the absence of folliculogenesis and is considered an adverse effect of chemotherapeutic drugs, which leads to infertility. Subsequently, the existing inquiry was achieved by exploring the potential suspicious influences of lemon peel extract (LPE), and resveratrol (RES) on cyclophosphamide (CPA) induced-POF. The results showed that CPA-induced POF significantly decreased serum estradiol (E2) and progesterone levels, along with a considerable rise in serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels. Moreover, CPA administration to rats significantly increased the serum level of Malondialdehyde (MDA) and significantly lowered the levels of reduced glutathione (GSH) and superoxide dismutase (SOD); in addition, it increased nuclear factor kappa B (NF-κB) levels, tumor necrosis factor-α (TNF-α), as well as cyclooxygenase 2 (COX-2) with the spread expression of inducible nitric oxide synthase (iNOS) mRNA levels and caspase-3 (Casp3) levels in ovarian tissues versus the control rats. However, treatment with LPE and RES suppressed the triggering of NF- κB pathways, evidenced by a considerable reduction in Casp3 & iNOS mRNA expression level and significant ameliorative effects in all evaluated parameters, as confirmed by the histological and immunohistochemical investigation when comparing the model group. In overall findings, both lemon peel extract and resveratrol can mitigate the adverse effects of CPA-induced POF. Most crucially, its combination therapy is a promising pharmacological agent for this disease.

Hepatic Macrophage Abundance and Phenotype in Aging and Liver Iron Accumulation

Liver macrophages serve important roles in iron homeostasis through phagocytosis of effete erythrocytes and the export of iron into the circulation. Conversely, intracellular iron can alter macrophage phenotype. Aging increases hepatic macrophage number and nonparenchymal iron, yet it is unknown whether age-related iron accumulation alters macrophage number or phenotype. To evaluate macrophages in a physiological model of iron loading that mimicked biological aging, young (6 mo) Fischer 344 rats were given one injection of iron dextran (15 mg/kg), and macrophage number and phenotype were evaluated via immunohistochemistry. A separate group of old (24 mo) rats was treated with 200 mg/kg deferoxamine every 12 h for 4 days. Iron administration to young rats resulted in iron concentrations that matched the values and pattern of tissue iron deposition observed in aged animals; however, iron did not alter macrophage number or phenotype. Aging resulted in significantly greater numbers of M1 (CD68⁺) and M2 (CD163⁺) macrophages in the liver, but neither macrophage number nor phenotype were affected by deferoxamine. Double-staining experiments demonstrated that both M1 (iNOS⁺) and M2 (CD163⁺) macrophages contained hemosiderin, suggesting that macrophages of both phenotypes stored iron. These results also suggest that age-related conditions other than iron excess are responsible for the accumulation of hepatic macrophages with aging.

Gadolinium chloride protects neurons by regulating the activation of microglia in the model of optic nerve crush

The pathological basis of optic nerve crush (ONC) is the apoptosis of retinal ganglion cells (RGCs), which leads to an irreversible impairment of visual function. When stimulated by external stimuli, microglia polarize into different types and play different roles in repairing retinal injury. In this study, gadolinium chloride (GdCl₃) could inhibit the excessive proliferation and activation of microglia in the retina after ONC and significantly inhibited the morphological changes of microglia in the ganglion cell layer (GCL) and inner plexiform layer (IPL). In the early stage of optic nerve injury, blood-derived immune cells did not play an essential role in retinal repair. In addition, transcriptome analysis showed that GdCl₃ inhibited the expression of microglia proliferation-related factors and regulated signaling pathways related to skeletonization and inflammation. After GdCl₃ treatment, M1 markers were significantly down-regulated, while M2 markers were increased. In conclusion, this study demonstrated that GdCl₃ could regulate the distribution and morphological change of the retinal microglia and protect the ganglion cells by eliminating M1 microglia selectively, which provided a theoretical basis for further localizing different types of microglia in retina related diseases.

The preventive effects of colony-stimulating factor 1 receptor (CSF-1R) inhibition on bladder outlet obstruction induced remodeling

INTRODUCTION

Bladder outlet obstruction (BOO) is a common problem that can affect bladder structure and function. Currently, there is no effective drugs available to prevent BOO-induced remodeling. Previous reports have demonstrated that the pathogenesis of BOO is associated with macrophage infiltration and polarization, which is physiologically dependent on colony-stimulating factor 1 receptor (CSF-1R) activation. Here we utilized a highly selective CSF-1R inhibitor, GW2580, to determine its preventive effects on BOO-induced remodeling.

METHODS

A total of 24 Sprague-Dawley rats were randomly divided into sham, BOO + vehicle, and BOO + GW2580 group. GW2580 or vehicle control was administrated by oral gavage at daily doses of 40 mg/kg for 6 weeks. Bladder samples were collected for histopathology, immunohistochemistry, immunofluorescence, western blotting, and flow cytometry analysis.

RESULTS

Our results demonstrated that bladder fibrosis was ameliorated by GW2580 compared with the vehicle group (22.01% ± 5.13% vs. 32.15% ± 7.24%, p < 0.01). Furthermore, treatment with GW2580 induced an inhibition of macrophage infiltration (4.41% ± 1.28% vs. 13.57% ± 3.42%, p < 0.001) and M2 macrophage polarization (10.67% ± 4.15% vs. 28.59% ± 6.38%, p < 0.001). There was also a decrease of profibrotic F4/80⁺  α-smooth muscle actin⁺ (α-SMA⁺ ) macrophage to myofibroblast transition (9.11% ± 2.58% vs. 17.33% ± 4.01%, p < 0.001) and CD163⁺ TGF-β1⁺ cells (7.68% ± 2.10% vs. 14.17% ± 4.09%, p < 0.01) in the GW2580 group when compared with the vehicle group.

CONCLUSIONS

In summary, our findings showed that GW2580 is a worthwhile candidate for a follow-up study to test in the treatment of BOO-induced remodeling.

A preliminary study of the innate immune memory of Kupffer cells induced by PEGylated nanoemulsions

The accelerated blood clearance (ABC) phenomenon describes a dilemma of polyethylene glycol (PEG) applied in drug delivery system (DDS) caused by its immunogenicity, that results in the enhanced blood clearance rate and increased hepatic and splenic accumulation after secondary injection of PEGylated nanocarriers. However, the ABC index, as the judgement of ABC phenomenon, only describes the accelerated blood clearance rate, but ignores the enhanced hepatic and splenic accumulation. Therefore, we proposed the hepatic accumulation (HA) index and the splenic accumulation (SA) index as supplements for assessing the ABC phenomenon, to emphasize the contribution of liver and spleen, especially the liver, possessing the most population of tissue resident macrophages. By altering the first injection site from the tail vein to the liver portal vein, there was no impact on anti-PEG IgM production, and the secondary hepatic accumulation of PEGylated nanoemulsions (PE) was observed to be proportionate to the first PE stimulation strength on the liver. We also determined that Kupffer cells (KCs) were the main contributor to this enhancement. On this basis, we revealed a definite phenomenon that PE could induce innate immune memory in KCs, by enhancing the phagocytosis of KCs toward PE during the secondary stimulation. The PE-stimulated KCs could carry this memory to the naïve rats through adoptive transfer, resulting in increased hepatic accumulation in the recipient rats without antibody production. Studies examining the phagocytosis of KCs in vivo, ex vivo and in vitro revealed that the memory of KCs against PE triggered by first-stimulated PE could be maintained independently of other cells or components until 21 days after the first stimulation, and possessing specificity to PEG, which was invalid to long-circulating GE (GM1 modified nanoemulsions). The discovery of immune memory in KCs induced by PE highlights the importance of focusing on the relationship between the innate immune system and PEGylated nanocarriers during the development of DDS to improve medication safety in the clinic.

Transcriptome-Wide Analysis of Human Liver Reveals Age-Related Differences in the Expression of Select Functional Gene Clusters and Evidence for a PPP1R10-Governed 'Aging Cascade'

A transcriptome-wide analysis of human liver for demonstrating differences between young and old humans has not yet been performed. However, identifying major age-related alterations in hepatic gene expression may pinpoint ontogenetic shifts with important hepatic and systemic consequences, provide novel pharmacogenetic information, offer clues to efficiently counteract symptoms of old age, and improve the overarching understanding of individual decline. Next-generation sequencing (NGS) data analyzed by the Mann-Whitney nonparametric test and Ensemble Feature Selection (EFS) bioinformatics identified 44 transcripts among 60,617 total and 19,986 protein-encoding transcripts that significantly (p = 0.0003 to 0.0464) and strikingly (EFS score > 0.3:16 transcripts; EFS score > 0.2:28 transcripts) differ between young and old livers. Most of these age-related transcripts were assigned to the categories 'regulome', 'inflammaging', 'regeneration', and 'pharmacogenes'. NGS results were confirmed by quantitative real-time polymerase chain reaction. Our results have important implications for the areas of ontogeny/aging and the age-dependent increase in major liver diseases. Finally, we present a broadly substantiated and testable hypothesis on a genetically governed 'aging cascade', wherein PPP1R10 acts as a putative ontogenetic master regulator, prominently flanked by IGFALS and DUSP1. This transcriptome-wide analysis of human liver offers potential clues towards developing safer and improved therapeutic interventions against major liver diseases and increased insights into key mechanisms underlying aging.

Salvia officinalis Extract and 17β-Estradiol Suppresses Ovariectomy Induced Osteoporosis in Female Rats

&lt;b&gt;Background and Objective:&lt;/b&gt; Osteoporosis is a progressive metabolic disorder characterized by an impaired bone formation that leads to increased morbidity and mortality.&lt;i&gt; Salvia officinalis &lt;/i&gt;is a source of phytoestrogens that could help mitigate the risk of osteoporotic rat fracture by exerting sex hormones. Therefore, the present study was designed to investigate the curative effect of &lt;i&gt;Salvia officinalis &lt;/i&gt;Extract&lt;i&gt; &lt;/i&gt;(SOE) and&lt;i&gt; &lt;/i&gt;17β-estradiol (E&lt;sub&gt;2&lt;/sub&gt;) and their combination&lt;i&gt; &lt;/i&gt;on bone loss in female rats with ovariectomy-induced estrogen deficiency &lt;b&gt;Materials and Methods:&lt;/b&gt; Forty adult female albino rats were divided into five groups, which included Sham control (Sham), ovariectomy (OVX), OVX+SOE, OVX+E&lt;sub&gt;2&lt;/sub&gt; and OVX +SOE+E&lt;sub&gt;2&lt;/sub&gt;.&lt;i&gt; &lt;/i&gt;SOE (10 mL kg&lt;sup&gt;&lt;/sup&gt;&lt;sup&gt;1&lt;/sup&gt;) and E&lt;sub&gt;2&lt;/sub&gt; (30 μg kg&lt;sup&gt;&lt;/sup&gt;&lt;sup&gt;1&lt;/sup&gt;) had been daily gavaged in the OVX+SOE, OVX+E&lt;sub&gt;2&lt;/sub&gt; and OVX+SOE+E&lt;sub&gt;2&lt;/sub&gt;, respectively for 6-weeks. &lt;b&gt;Results:&lt;/b&gt; The model of ovariectomy resulted in osteoporosis as demonstrated by the decreased serum Ca, P, vitamin D, E&lt;sub&gt;2&lt;/sub&gt; level associated with a significant increase in PTH levels in comparison to the sham control group. Besides, OVX to rats caused up-regulation in the levels of CTX-1, P1NP, BALP, OC and RANKL comparable to the sham control group. Moreover, SOE and E&lt;sub&gt;2&lt;/sub&gt; significantly modulated the calciotropic parameters and improved all bone turnover markers as well as RANKL as compared to the OVX group. However, Histopathological and immunohistochemical results showed defective mineralization with the destruction of the bone matrix and increased TNF-α expression from the OVX group relative to the treated groups. &lt;b&gt;Conclusion:&lt;/b&gt; These results suggest that both SOE and E&lt;sub&gt;2&lt;/sub&gt; or their combined administration are efficient inhibitors against ovariectomy-induced bone loss in female rats.

The roles of MCP-1/CCR2 mediated macrophage recruitment and polarization in bladder outlet obstruction (BOO) induced bladder remodeling

Bladder outlet obstruction (BOO) can lead to alternation of bladder structure and function, known as bladder remodeling. Macrophage is a heterogeneous cell type and implicated in immunity regulating and tissue repairment. The relationship between macrophage and BOO remains unclear. We determined the pivotal role of macrophage recruitment and polarization in bladder remodeling. Sprague-Dawley rats underwent surgical operation of a BOO for either 1, 3, 6 weeks and were compared with sham-operated rats. The BOO rats in the experimental group were orally administrated with 5 mg/kg RS-504393, a C-C chemokine receptor (CCR2) antagonist, for 6 weeks, and the rats in the control group were treated with vehicle. Bladder tissues were harvested for assays of flow cytometry, quantitative reverse transcription polymerase chain reaction, histological examinations, immunohistochemistry staining and immunofluorescence. After induction of BOO, M1 macrophages were predominantly observed at inflammatory stage while M2 macrophages were mainly found during fibrosis stage. Flow cytometry analysis revealed that the ratio of M1/M2 significantly increased at 3 weeks (P = 0.0013) when compared to the sham-operated group. Interestingly, our results showed that M2 macrophages promoted BOO-induced fibrosis through indirectly secreting TGF-β and directly transforming to collagen-producing myofibroblast. Additionally, RS-504393 treatment significantly decreased the number of M1 and M2 macrophage infiltration in bladder tissue, and bladder fibrosis was attenuated by RS-504393 treatment compared with that in the vehicle-treated rats. In summary, macrophages play a pivotal role in bladder remodeling and targeting MCP-1/CCR2 signaling pathway might be a therapeutic strategy for human bladder fibrosis.

Hepatic macrophage accumulation with aging: cause for concern?

Aging is associated with chronic, low-grade inflammation that adversely affects physiological function. The liver regulates systemic inflammation; it is a source of cytokine production and also scavenges bacteria from the portal circulation to prevent infection of other organs. The cells with primary roles in these functions, hepatic macrophages, become more numerous in the liver with "normal" aging (i.e., in the absence of disease). Here, we demonstrate evidence and potential mechanisms for this phenomenon, which include augmented tumor necrosis factor-α (TNF-α) and intercellular adhesion molecule-1 (ICAM-1) expression in the liver. Also, we discuss how an age-related impairment in autophagy within macrophages leads to a pro-oxidative state and ensuing production of proinflammatory cytokines, particularly interleukin 6 (IL-6). Given that the liver is a rich source of macrophages, we posit that it represents a major source of the elevated systemic IL-6 observed with aging, which is associated with physiological dysfunction. Testing a causal role for liver macrophage production of IL-6 during aging remains a challenge, yet interventions that have targeted macrophages and/or IL-6 have demonstrated promise in treating age-related diseases. These studies have demonstrated an age-related, deleterious reprogramming of macrophage function, which worsens pathology. Therefore, hepatic macrophage accrual is indeed a cause for concern, and therapies that attenuate the aged phenotype of macrophages will likely prove useful in promoting healthy aging.

Zoledronate Causes a Systemic Shift of Macrophage Polarization towards M1 In Vivo

BACKGROUND

Immunomodulatory properties of bisphosphonates (BP) are suggested to contribute to the development of medication-associated osteonecrosis of the jaw (MRONJ). Furthermore, bisphosphonate-derived immune modulation might contribute to the anti-metastatic effect observed in breast cancer patients. Macrophages are potential candidates for the mediation of immunomodulatory effects of bisphosphonates. The study aimed to investigate the influence of bisphosphonates alone and in combination with surgical trauma on systemic macrophage polarization (M1 vs. M2) using an in vivo rat model.

METHODS

A total of 120 animals were divided into four groups. Groups 2 and 4 were treated with 8 × 40 μg/kg body weight of the BP Zoledronate i.p. (week 0-7). Groups 3 and 4 were exposed to surgical trauma (week 8, tooth extraction + tibia fracture), whereas in Group 1 neither medication nor surgical trauma was applied. After 8, 10, 12 and 16 weeks, skin, lung and spleen were immunohistochemically examined for macrophage polarization via expression analysis of CD68, CD163 and iNOS using a tissue microarray (TMA).

RESULTS

A significant shift of macrophage polarization towards M1 was observed in skin, spleen and lung tissue of animals, with and without surgical trauma, treated with BP when compared to those without BP application. Surgical trauma did not cause a significant increase towards M1 polarization.

CONCLUSIONS

BP application leads to a systemic pro-inflammatory situation in vivo, independent of surgical trauma, as evidenced by the shift in macrophage polarization towards M1 in various somatic tissues. This provides a possible explanation for the clinically observed anti-tumor effect of bisphosphonates and might also contribute to pathogenesis of MRONJ.