Immunophenotypical Characterization of M1/M2 Macrophages and Lymphocytes in Cisplatin-Induced Rat Progressive Renal Fibrosis

Myofibroblast-derived exosomes enhance macrophages to myofibroblasts transition and kidney fibrosis

A critical event in the pathogenesis of kidney fibrosis is the transition of macrophages into myofibroblasts (MMT). Exosomes play an important role in crosstalk among cells in the kidney and the development of renal fibrosis. However, the role of myofibroblast-derived exosomes in the process of MMT and renal fibrosis progression remains unknown. Here, we examined the role of myofibroblast-derived exosomes in MMT and kidney fibrogenesis. In vitro, transforming growth factor-β1 stimulated the differentiation of kidney fibroblasts into myofibroblasts and promoted exosome release from myofibroblasts. RAW264.7 cells were treated with exosomes derived from myofibroblasts. We found purified exosomes from myofibroblasts trigger the MMT. By contrast, inhibition of exosome production with GW4869 or exosome depletion from the conditioned media abolished the ability of myofibroblasts to induce MMT. Mice treatment with myofibroblast-derived exosomes (Myo-Exo) exhibited severe fibrotic lesion and more abundant MMT cells in kidneys with folic acid (FA) injury, which was negated by TANK-banding kinase-1 inhibitor. Furthermore, suppression of exosome production reduced collagen deposition, extracellular matrix protein accumulation, and MMT in FA nephropathy. Collectively, Myo-Exo enhances the MMT and kidney fibrosis. Blockade of exosomes mediated myofibroblasts-macrophages communication may provide a novel therapeutic target for kidney fibrosis.

The role of macrophages in fibrosis of chronic kidney disease

Macrophages are widely distributed throughout various tissues of the body, and mounting evidence suggests their involvement in regulating the tissue microenvironment, thereby influencing disease onset and progression through direct or indirect actions. In chronic kidney disease (CKD), disturbances in renal functional homeostasis lead to inflammatory cell infiltration, tubular expansion, glomerular atrophy, and subsequent renal fibrosis. Macrophages play a pivotal role in this pathological process. Therefore, understanding their role is imperative for investigating CKD progression, mitigating its advancement, and offering novel research perspectives for fibrosis treatment from an immunological standpoint. This review primarily delves into the intrinsic characteristics of macrophages, their origins, diverse subtypes, and their associations with renal fibrosis. Particular emphasis is placed on the transition between M1 and M2 phenotypes. In late-stage CKD, there is a shift from the M1 to the M2 phenotype, accompanied by an increased prevalence of M2 macrophages. This transition is governed by the activation of the TGF-β1/SMAD3 and JAK/STAT pathways, which facilitate macrophage-to-myofibroblast transition (MMT). The tyrosine kinase Src is involved in both signaling cascades. By thoroughly elucidating macrophage functions and comprehending the modes and molecular mechanisms of macrophage-fibroblast interaction in the kidney, novel, tailored therapeutic strategies for preventing or attenuating the progression of CKD can be developed.

Effect of connexin 43 in LPS/IL-4-induced macrophage M1/M2 polarization: An observational study

Lipopolysaccharide (LPS) and interleukin-4 (IL-4) play important roles in inducing M1 and M2 macrophage polarization. Studies have shown that LPS can promote the polarization of macrophages to M1-type and produce many pro-inflammatory cytokines, while IL-4 can promote the polarization of macrophages to M2-type and produce many anti-inflammatory cytokines. Moreover, Connexin 43 (Cx43) is widely expressed in macrophages and has various regulatory functions. However, whether Cx43 is involved in the regulation of macrophage M1/M2 polarization has not been fully studied. This study examined the role of Cx43 and M2 polarization markers using Western blot, immunofluorescence, flow cytometry. Cx43 overexpression was induced using Cx43 overexpressing lentivirus. The statistical software SPSS 20.0 (IBM Corp.) and GraphPad Prism 8.0 (GraphPad Software, La Jolla, CA, United States) were used to analyze the results. P values < .05 were considered to indicate statistically significant differences. Our results showed that LPS promotes the polarization of macrophages to M1-type, which is accompanied by an increase in Cx43 expression from 0 to 24 hours. Moreover, the application of the Cx43-specific blockers Gap19 and Gap26 reduces the expression of macrophage M1-type polarization markers. Thus, the expression of Cx43 increases first, and then, due to the initiation of intracellular autophagy during LPS-induced macrophage M1 polarization. Cx43 is degraded and the expression of Cx43 decreases from 24 hours to 48 hours. IL-4 decreases the expression of Cx43 from 24 hours to 48 hours and promotes the transformation of macrophages to M2-type. The application of Cx43 overexpression lentivirus leads to a reduction in the expression of M2 polarization markers. IL-4-induced M2 polarization of macrophages inhibits cell autophagy, reducing Cx43 degradation and leading to an increase in Cx43 from 24 hours to 48 hours. Thus, Cx43 expression in M2-type polarization experiences a reduction at first and then an increase from 24 hours to 48 hours. The direction of macrophage polarization can be controlled by regulating the expression of Cx43, thus providing a theoretical basis for treating atherosclerosis, tumors, and other diseases associated with macrophage polarization.

An inflammation resolution-promoting intervention prevents atrial fibrillation caused by left ventricular dysfunction

AIMS

Recent studies suggest that bioactive mediators called resolvins promote an active resolution of inflammation. Inflammatory signalling is involved in the development of the substrate for atrial fibrillation (AF). The aim of this study is to evaluate the effects of resolvin-D1 on atrial arrhythmogenic remodelling resulting from left ventricular (LV) dysfunction induced by myocardial infarction (MI) in rats.

METHODS AND RESULTS

MI was produced by left anterior descending coronary artery ligation. Intervention groups received daily intraperitoneal resolvin-D1, beginning before MI surgery (early-RvD1) or Day 7 post-MI (late-RvD1) and continued until Day 21 post-MI. AF vulnerability was evaluated by performing an electrophysiological study. Atrial conduction was analysed by using optical mapping. Fibrosis was quantified by Masson's trichrome staining and gene expression by quantitative polymerase chain reaction and RNA sequencing. Investigators were blinded to group identity. Early-RvD1 significantly reduced MI size (17 ± 6%, vs. 39 ± 6% in vehicle-MI) and preserved LV ejection fraction; these were unaffected by late-RvD1. Transoesophageal pacing induced atrial tachyarrhythmia in 2/18 (11%) sham-operated rats, vs. 18/18 (100%) MI-only rats, in 5/18 (28%, P < 0.001 vs. MI) early-RvD1 MI rats, and in 7/12 (58%, P < 0.01) late-RvD1 MI rats. Atrial conduction velocity significantly decreased post-MI, an effect suppressed by RvD1 treatment. Both early-RvD1 and late-RvD1 limited MI-induced atrial fibrosis and prevented MI-induced increases in the atrial expression of inflammation-related and fibrosis-related biomarkers and pathways.

CONCLUSIONS

RvD1 suppressed MI-related atrial arrhythmogenic remodelling. Early-RvD1 had MI sparing and atrial remodelling suppressant effects, whereas late-RvD1 attenuated atrial remodelling and AF promotion without ventricular protection, revealing atrial-protective actions unrelated to ventricular function changes. These results point to inflammation resolution-promoting compounds as novel cardio-protective interventions with a particular interest in attenuating AF substrate development.

The Potential of Twendee X® as a Safe Antioxidant Treatment for Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by systemic skin hardening, which combines Raynaud's phenomenon and other vascular disorders, skin and internal organ fibrosis, immune disorders, and a variety of other abnormalities. Symptoms vary widely among individuals, and personalized treatment is sought for each patient. Since there is no fundamental cure for SSc, it is designated as an intractable disease with patients receiving government subsidies for medical expenses in Japan. Oxidative stress (OS) has been reported to play an important role in the cause and symptoms of SSc. HOCl-induced SSc mouse models are known to exhibit skin and visceral fibrosis, vascular damage, and autoimmune-like symptoms observed in human SSc. The antioxidant combination Twendee X® (TwX) is a dietary supplement consisting of vitamins, amino acids, and CoQ10. TwX has been proven to prevent dementia in humans with mild cognitive impairment and significantly improve cognitive impairment in an Alzheimer's disease mouse model by regulating OS through a strong antioxidant capacity that cannot be achieved with a single antioxidant ingredient. We evaluated the effectiveness of TwX on various symptoms of HOCl-induced SSc mice. TwX-treated HOCl-induced SSc mice showed significantly reduced lung and skin fibrosis compared to untreated HOCl-induced SSc mice. TwX also significantly reduced highly oxidized protein products (AOPP) in serum and suppressed Col-1 gene expression and activation of B cells involved in autoimmunity. These findings suggest that TwX has the potential to be a new antioxidant treatment for SSc without side effects.

Protective Effect of Platelet-Rich Plasma on Cisplatin-Induced Nephrotoxicity in Adult Male Albino Rats: Histological and Immunohistochemical Study

Cisplatin is a potent antineoplastic drug that is used for treatment of many solid tumors. It has a wide range of adverse effects. Nephrotoxicity is the most common one of them. Platelet-rich plasma (PRP) is an autologous human plasma that activates the tissue regeneration through cell proliferation and differentiation. Study the role of PRP in amelioration of cisplatin-induced nephrotoxicity on the kidney of adult male albino rats by biochemical, morphometric, histological, and immunohistochemical studies. Thirty-five adult male albino rats were used. Thirty rats were included as experimental group and five were used to obtain the PRP. The experimental group was classified into as follows: control group which received 1mL of sterile saline by intraperitoneal injection (IP), cisplatin-treated group which received cisplatin 7.5 mg/kg IP in a single dose and cisplatin and PRP-treated group rats received cisplatin 7.5 mg/kg single IP dose followed by 1ml of PRP IP after 24 h of cisplatin injection. There was a significant increase in urea and creatinine levels in cisplatin-treated group in comparison to the control and the PRP groups. The kidneys of cisplatin-treated group showed distorted renal structure, where specimens of PRP-treated group revealed restoration of the classical appearance of the renal tissue similar to the control group. PRP has protective effects on renal structure and functions and it helps to ameliorate the histological changes induced by cisplatin.

Macrophages polarization in renal inflammation and fibrosis animal models (Review)

Chronic kidney disease (CKD) is a significant public health concern. Renal fibrosis is the final common pathway in the progression of kidney diseases, irrespective of the initial injury. Substantial evidence underscores the pivotal role of renal inflammation in the genesis of renal fibrosis. The presence of macrophages within normal renal tissue is significantly increased within diseased renal tissue, indicative of their crucial regulatory function in inflammation and fibrosis. Macrophages manifest a high degree of heterogeneity, exhibiting distinct phenotypic and functional traits in response to diverse stimuli within the local microenvironment in various types of kidney diseases. Broadly, macrophages are categorized into two principal groups: Classically activated, designated as M1 macrophages and alternatively activated, designated as M2 macrophages. A number of experimental models are widely used to study the underlying mechanisms driving renal inflammation and fibrosis progression. The present review delineated the phenotypic and functional attributes of macrophages present in diverse induced models, analyzing their disposition in relation to M1 and M2 polarization states.

Adipose Stromal Cell-Derived Secretome Attenuates Cisplatin-Induced Injury In Vitro Surpassing the Intricate Interplay between Proximal Tubular Epithelial Cells and Macrophages

(1) Background: The chemotherapeutic drug cisplatin exerts toxic side effects causing acute kidney injury. Mesenchymal stromal cells can ameliorate cisplatin-induced kidney injury. We hypothesize that the MSC secretome orchestrates the vicious cycle of injury and inflammation by acting on proximal tubule epithelial cells (PTECs) and macrophages individually, but further by counteracting their cellular crosstalk. (2) Methods: Conditioned medium (CM) from adipose stromal cells was used, first assessing its effect on cisplatin injury in PTECs. Second, the effects of cisplatin and the CM on macrophages were measured. Lastly, in an indirect co-culture system, the interplay between the two cell types was assessed. (3) Results: First, the CM rescued PTECs from cisplatin-induced apoptosis by reducing oxidative stress and expression of nephrotoxicity genes. Second, while cisplatin exerted only minor effects on macrophages, the CM skewed macrophage phenotypes to the anti-inflammatory M2-like phenotype and increased phagocytosis. Finally, in the co-culture system, the CM suppressed PTEC death by inhibiting apoptosis and nuclei fragmentation. The CM lowered TNF-α release, while cisplatin inhibited macrophage phagocytosis, PTECs, and the CM to a greater extent, thus enhancing it. The CM strongly dampened the inflammatory macrophage cytokine secretion triggered by PTECs. (4) Conclusions: ASC-CM surpasses the PTEC-macrophage crosstalk in cisplatin injury. The positive effects on reducing cisplatin cytotoxicity, on polarizing macrophages, and on fine-tuning cytokine secretion underscore MSCs' CM benefit to prevent kidney injury progression.

LncRNA CASC2 Alleviates Renal Interstitial Inflammation and Fibrosis through MEF2C Downregulation-Induced Hinderance of M1 Macrophage Polarization

INTRODUCTION

Long noncoding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2) alleviates the progression of diabetic nephropathy by inhibiting inflammation and fibrosis. This study investigated how CASC2 impacts renal interstitial fibrosis (RIF) through regulating M1 macrophage (M1) polarization.

METHOD

Nine-week-old mice underwent unilateral ureteral obstruction (UUO) establishment. Macrophages were induced toward M1 polarization using lipopolysaccharide (LPS) in vitro and cocultured with fibroblasts to examine how M1 polarization influences RIF. LnCeCell predicted that CASC2 interacted with myocyte enhancer factor 2 C (MEF2C), which was validated by dual-luciferase reporter assay. CASC2/MEF2C overexpression was achieved by lentivirus-expressing lncRNA CASC2 injection in vivo or CASC2 and MEF2C transfection in vitro. Renal injury was evaluated through biochemical analysis and hematoxylin-eosin/Masson staining. Macrophage infiltration and M1 polarization in the kidney and/or macrophages were detected by immunofluorescence, flow cytometry, and/or quantitative reverse transcription polymerase chain reaction (qRT-PCR). Expressions of CASC2, MEF2C, and markers related to inflammation/M1/fibrosis in the kidney/macrophages/fibroblasts were analyzed by qRT-PCR, fluorescence in situ hybridization, enzyme-linked immunosorbent assay, and/or Western blot.

RESULT

In the kidneys of mice, CASC2 was downregulated and macrophage infiltration was promoted time-dependently from days 3 to 14 post-UUO induction; CASC2 overexpression alleviated renal histological abnormalities, hindered macrophage infiltration and M1 polarization, downregulated renal function markers serum creatinine and blood urea nitrogen and inflammation/M1/fibrosis-related makers, and offset UUO-induced MEF2C upregulation. LncRNA CASC2 overexpression inhibited fibroblast fibrosis and M1 polarization in cocultured fibroblasts with LPS-activated macrophages. Also, CASC2 bound to MEF2C and inhibited its expression in LPS-activated macrophages. Furthermore, MEF2C reversed the inhibitory effects of lncRNA CASC2 overexpression.

CONCLUSION

CASC2 alleviates RIF by inhibiting M1 polarization through directly downregulating MEF2C expression. CASC2 might represent a promising value of future investigations on treatment for RIF.

Depletion of macrophages with clodronate liposomes partially attenuates renal fibrosis on AKI-CKD transition

Clodronate liposomes are bisphosphonates encapsulated by liposomes that are known to induce macrophage depletion in vivo. In a previous study, clodronate liposomes improved renal ischemia/reperfusion (I/R) injury in mice, which may be due to effects on macrophage phenotypes. However, how inflammatory cytokines secretion participates is unknown. In this study, we investigated the effect of macrophages in the I/R kidney by depleting macrophages with clodronate liposomes and changing inflammatory cytokines. C57BL/6 mice underwent I/R injury with or without clodronate liposomes administration on Days 5 and 15. Tubular injury, collagen deposition, and fibrosis were detected and analyzed by histological staining, immunocytochemistry (IHC), flow cytometry (FACS), and reverse transcription-polymerase chain reaction (RT-PCR). Inflammatory cytokines were detected and analyzed by Western blotting and RT-PCR. We found that clodronate liposomes alleviated renal fibrosis and tissue damage on both Days 5 and 15. KIM-1, IL-10, and TGF-β were reduced significantly in the clodronate liposomes treatment group. However, TNF-α was not different between the clodronate liposomes treatment group and the phosphate-buffered saline treatment group on either Day 5 or Day 15. Thus, clodronate liposomes can alleviate renal fibrosis and tissue damage and reduce the inflammatory cytokines IL-10 and TGF-β, suggesting that clodronate liposomes alleviate renal fibrosis may because of M1/M2 polarization.

Berberine ameliorates renal interstitial inflammation and fibrosis in mice with unilateral ureteral obstruction

Berberine acts via multiple pathways to alleviate fibrosis in various tissues and shows renoprotective effects. However, its role and underlying mechanisms in renal fibrosis remain unclear. Herein, we aimed to investigate the protective effects and molecular mechanisms of berberine against unilateral ureteric obstruction-induced renal fibrosis. The results indicated that berberine treatment (50 mg/kg/day) markedly alleviated histopathological alterations, collagen deposition and inflammatory cell infiltration in kidney tissue and restored mouse renal function. Mechanistically, berberine intervention inhibited NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation and the levels of the inflammatory cytokine IL-1β in the kidneys of unilateral ureteric obstruction mice. In addition, berberine relieved unilateral ureteric obstruction-induced renal injury by activating adenosine monophosphate-activated protein kinase (AMPK) signalling and promoting fatty acid β-oxidation. In vitro models showed that berberine treatment prevented the TGF-β1-induced profibrotic phenotype of hexokinase 2 (HK-2) cells, characterized by loss of an epithelial phenotype (alpha smooth muscle actin [α-SMA]) and acquisition of mesenchymal marker expression (E-cadherin), by restoring abnormal fatty acid β-oxidation and upregulating the expression of the fatty acid β-oxidation related-key enzymes or regulators (phosphorylated-AMPK, peroxisome proliferator activated receptor alpha [PPARα] and carnitine palmitoyltransferase 1A [CPT1A]). Collectively, berberine alleviated renal fibrosis by inhibiting NLRP3 inflammasome activation and protected tubular epithelial cells by reversing defective fatty acid β-oxidation. Our findings might be exploited clinically to provide a potential novel therapeutic strategy for renal fibrosis.

Macrophage RAGE deficiency prevents myocardial fibrosis by repressing autophagy-mediated macrophage alternative activation

Myocardial fibrosis (MF) is the characteristic pathological feature of various cardiovascular diseases that lead to heart failure (HF) or even fatal outcomes. Alternatively, activated macrophages are involved in the development of fibrosis and tissue remodeling. Although the receptor for advanced glycation end products (RAGE) is involved in MF, its potential role in regulating macrophage function in cardiac fibrosis has not been fully investigated. We aimed to determine the role of macrophage RAGE in transverse aortic constriction (TAC)-induced MF. In this study, we found that RAGE expression was markedly increased in the infiltrated alternatively activated macrophages within mice hearts after TAC. RAGE knockout mice showed less infiltration of alternatively activated macrophages and attenuated cardiac hypertrophy and fibrosis compared to the wild-type mice. Our data suggest that mice with macrophage-specific genetic deletion of RAGE were protected from interstitial fibrosis and cardiac dysfunction when subjected to pressure overload, which led to a decreased proportion of alternatively activated macrophages in heart tissues. Our in vitro experiments demonstrated that RAGE deficiency inhibited the differentiation into alternatively activated macrophages by suppressing autophagy activation. In the co-culture system, in vitro polarization of RAW264.7 macrophages toward an alternatively activated phenotype stimulated the expression of α-smooth muscle actin and collagen in cardiac fibroblasts. However, the knockdown of RAGE and inhibition of autophagy in macrophages showed reduced fibroblast-to-myofibroblast transition (FMT). Collectively, our results suggest that RAGE plays an important role in the recruitment and activation of alternatively activated macrophages by regulating autophagy, which contributes to MF. Thus, blockage of RAGE signaling may be an attractive therapeutic target for the treatment of hypertensive heart disease.

The effects of the differentiated macrophages by dexamethasone on the immune responses

The characteristics of M2 macrophages suggest immunotherapeutic approaches for inducing immunological tolerance. The current study aimed to evaluate the effect of Dexamethasone (Dex) treatment on monocytes polarization and its impact on immune responses. The monocytes were extracted from the rat's blood samples. The effects of Dex concentration and treatment duration on monocyte viability, phagocytosis of rabbit red blood cell (RRBC) antigens, and cytokine gene expression were evaluated using MTT, ELISA, and Real-Time PCR analysis, respectively. The monocytes treated with Dex were injected into the rats as an autograft. The effects of the grafted cells were assessed on immune responses, monocyte differentiation, and pathological lesions, in comparison to the control groups. Treatment of monocytes with 10-5 M of Dex for 48 h increased the expression of IL-10 and TGF-β genes, while reducing the expression of TNF-α and IL-1 genes. The monocytes treated with antigen and Dex showed higher CD206 gene expression compared to CD80. The cells that were treated with Dex had the highest concentration of antigens after five days. Administration of the grafted cells to the animals has some significant effects on innate immune responses and no impact on pathological lesions. The group that received cells treated with Dex and antigen experienced a significant decrease in anti-RBC antibody titers. Additionally, there was a significant difference in the expression of cytokine genes and M2 differentiation markers among the groups that were evaluated. The effects of Dex on the viability and differentiation of monocytes depend on the dosage, timing, and duration of the treatment.

Immunohistochemical Characterization of M1, M2, and M4 Macrophages in Leprosy Skin Lesions

Mycobacterium leprae is the etiological agent of leprosy. Macrophages (Mφs) are key players involved in the pathogenesis of leprosy. In this study, immunohistochemical analysis was performed to examine the phenotype of Mφ subpopulations, namely M1, M2, and M4, in the skin lesions of patients diagnosed with leprosy. Based on the database of treatment-naïve patients treated between 2015 and 2019 at the Department of Dermatology of the University of the State of Pará, Belém, routine clinical screening samples were identified. The monolabeling protocol was used for M1 macrophages (iNOS, IL-6, TNF-α) and M2 macrophages (IL-10, IL-13, CD163, Arginase 1, TGF-β, FGFb), and the double-labeling protocol was used for M4 macrophages (IL-6, MMP7, MRP8, TNF-α e CD68). To confirm the M4 macrophage lineage, double labeling of the monoclonal antibodies CD68 and MRP8 was also performed. Our results demonstrated a statistically significant difference for the M1 phenotype among the Virchowian (VV) (4.5 ± 1.3, p < 0.0001), Borderline (1.6 ± 0.4, p < 0.0001), and tuberculoid (TT) (12.5 ± 1.8, p < 0.0001) clinical forms of leprosy. Additionally, the M2 phenotype showed a statistically significant difference among the VV (12.5 ± 2.3, p < 0.0001), Borderline (1.3 ± 0.2, p < 0.0001), and TT (3.2 ± 0.7, p < 0.0001) forms. For the M4 phenotype, a statistically significant difference was observed in the VV (9.8 ± 1.7, p < 0.0001), Borderline (1.2 ± 0.2, p < 0.0001), and TT (2.6 ± 0.7, p < 0.0001) forms. A significant correlation was observed between the VV M1 and M4 (r = 0.8712; p = 0.0000) and between the VV M2 × TT M1 (r = 0.834; p = 0.0002) phenotypes. The M1 Mφs constituted the predominant Mφ subpopulation in the TT and Borderline forms of leprosy, whereas the M2 Mφs showed increased immunoexpression and M4 was the predominant Mφ phenotype in VV leprosy. These results confirm the relationship of the Mφ profile with chronic pathological processes of the inflammatory response in leprosy.

M2 macrophage-derived exosomes promote diabetic fracture healing by acting as an immunomodulator

Diabetes mellitus is a chronically inflamed disease that predisposes to delayed fracture healing. Macrophages play a key role in the process of fracture healing by undergoing polarization into either M1 or M2 subtypes, which respectively exhibit pro-inflammatory or anti-inflammatory functions. Therefore, modulation of macrophage polarization to the M2 subtype is beneficial for fracture healing. Exosomes perform an important role in improving the osteoimmune microenvironment due to their extremely low immunogenicity and high bioactivity. In this study, we extracted the M2-exosomes and used them to intervene the bone repair in diabetic fractures. The results showed that M2-exosomes significantly modulate the osteoimmune microenvironment by decreasing the proportion of M1 macrophages, thereby accelerating diabetic fracture healing. We further confirmed that M2-exosomes induced the conversion of M1 macrophages into M2 macrophages by stimulating the PI3K/AKT pathway. Our study offers a fresh perspective and a potential therapeutic approach for M2-exosomes to improve diabetic fracture healing.

Role of Caveolin-1 on the molybdenum and cadmium exposure induces pulmonary ferroptosis and fibrosis in the sheep

Molybdenum (Mo) is an essential trace element that exists in all tissues of the human body, but excessive Mo intake has a toxic effect. Cadmium (Cd) is a widely known and harmful heavy metal that exists in the environment. Although studies on Mo and Cd are available, it is still unknown how the combination of Mo and Cd causes pulmonary injury. Forty-eight sheep that were 2 months old were chosen and randomly separated into four groups as follows: Control group, Mo group, Cd group, and Mo + Cd group. The experiment lasted 50 days. The results showed that Mo and/or Cd caused significant pathological damage and oxidative stress in the lungs of sheep. Moreover, Mo and/or Cd exposure could downregulate the expression levels of xCT (SLC7A11 and SLC3A2), GPX4 and FTH-1 and upregulate the expression levels of PTGS2 and NCOA4, which led to iron overload and ferroptosis. Ferroptosis induced Wnt/β-catenin-mediated fibrosis by elevating the expression levels of Caveolin-1 (CAV-1), Wnt 1, Wnt3a, β-catenin (CTNNB1), TCF4, Cyclin D1, mmp7, α-SMA (ACTA2), Collagen 1 (COL1A1) and Vimentin. These changes were particularly noticeable in the Mo and Cd combination group. In conclusion, these data demonstrated that Mo and/or Cd exposure led to lung ferroptosis by inhibiting the SLC7A11/GSH/GPX4 axis, which in turn increases CAV-1 expression and subsequently activates the Wnt/β-catenin pathway, leading to fibrosis in sheep lungs.

Stem cell pathology: histogenesis of malignant fibrous histiocytoma and characterization of myofibroblasts appearing in fibrotic lesions

The concept of "stem cell pathology" is to establish the role of the stem cells by exploring their contribution to lesion development. The somatic stem cells are present in the body. Malignant fibrous histiocytoma (MFH; recently named "undifferentiated pleomorphic sarcoma") includes pluripotential undifferentiated mesenchymal stem cells as a cell element. An antibody (A3) generated by using rat MFH cells as the antigen labels somatic stem cells such as bone marrow stem cells and immature endothelial cells and pericytes, as well as immature epithelial cells in epithelialization. By using A3 and other antibodies recognizing somatic stem cells, it is considered that myofibroblasts appearing in rat fibrotic lesions are developed partly from immature hepatic stellate cells in hepatic fibrosis, immature pancreatic stellate cells in pancreatic fibrosis, pericytes/endothelial cells in neovascularization in injured tissues, as well as via the epithelial-mesenchymal transition. These progenitors may be in the stem cell lineage. In this review, the author introduces the histogenesis of MFH and the characteristics of myofibroblasts appearing in fibrosis, based mainly on the author's studies.

Analyses of damage-associated molecular patterns, particularly biglycan, in cisplatin-induced rat progressive renal fibrosis

Damage-associated molecular patterns (DAMPs) and their receptors (TLR-2 and -4) may play important roles in renal fibrosis, of which the pathogenesis is complicated. We used rat renal lesions induced by a single intraperitoneal injection of cisplatin at 6 mg/kg body weight; consisting of tissue damage of renal tubules on days 1 and 3, further damage and regeneration with inflammation mainly on days 5 and 7, and interstitial fibrosis on days 9, 12, 15, and 20. Microarray analyses on days 5 (the commencement of inflammation) and 9 (the commencement of interstitial fibrosis) showed that DAMPs increased by more than two-fold relative to control included common extra-cellular matrix (ECM) components such as laminin (Lamc2) and fibronectin, and heat shock protein family, as well as fibrinogen, although it was limited analysis; Lamc2, an element of basement membrane, may be regarded as an indicator for damaged renal tubules. In the real-time RT-PCR analyses, TLR-2 significantly increased transiently on day 1, whereas TLR-4 significantly increased on days 9 and 15, almost in agreement with the increased biglycan (a small leucine-rich proteoglycan as ubiquitous ECM component). As M1/M2 macrophages participated in renal lesions, such as inflammation and fibrosis, presumably, TLR-4, which may be expressed in immune cells, could play crucial roles in the formation of renal lesions in association with biglycan.

Molecular Mechanisms and Risk Factors Related to the Pathogenesis of Peyronie's Disease

Peyronie's disease (PD) is a benign condition caused by plaque formation on the tunica albuginea of the penis. It is associated with penile pain, curvature, and shortening, and contributes to erectile dysfunction, which worsens patient quality of life. In recent years, research into understanding of the detailed mechanisms and risk factors involved in the development of PD has been increasing. In this review, the pathological mechanisms and several closely related signaling pathways, including TGF-β, WNT/β-catenin, Hedgehog, YAP/TAZ, MAPK, ROCK, and PI3K/AKT, are described. Findings regarding cross-talk among these pathways are then discussed to elucidate the complicated cascade behind tunica albuginea fibrosis. Finally, various risk factors including the genes involved in the development of PD are presented and their association with the disease summarized. The purpose of this review is to provide a better understanding regarding the involvement of risk factors in the molecular mechanisms associated with PD pathogenesis, as well as to provide insight into disease prevention and novel therapeutic interventions.

Regulatory Mechanism of M1/M2 Macrophage Polarization in the Development of Autoimmune Diseases

Macrophages are innate immune cells in the organism and can be found in almost tissues and organs. They are highly plastic and heterogeneous cells and can participate in the immune response, thereby playing a crucial role in maintaining the immune homeostasis of the body. It is well known that undifferentiated macrophages can polarize into classically activated macrophages (M1 macrophages) and alternatively activated macrophages (M2 macrophages) under different microenvironmental conditions. The directions of macrophage polarization can be regulated by a series of factors, including interferon, lipopolysaccharide, interleukin, and noncoding RNAs. To elucidate the role of macrophages in various autoimmune diseases, we searched the literature on macrophages with the PubMed database. Search terms are as follows: macrophages, polarization, signaling pathways, noncoding RNA, inflammation, autoimmune diseases, systemic lupus erythematosus, rheumatoid arthritis, lupus nephritis, Sjogren's syndrome, Guillain-Barré syndrome, and multiple sclerosis. In the present study, we summarize the role of macrophage polarization in common autoimmune diseases. In addition, we also summarize the features and recent advances with a particular focus on the immunotherapeutic potential of macrophage polarization in autoimmune diseases and the potentially effective therapeutic targets.

Atherosclerosis and Inflammation: Insights from the Theory of General Pathological Processes

Recent advances have greatly improved our understanding of the molecular mechanisms behind atherosclerosis pathogenesis. However, there is still a need to systematize this data from a general pathology perspective, particularly with regard to atherogenesis patterns in the context of both canonical and non-classical inflammation types. In this review, we analyze various typical phenomena and outcomes of cellular pro-inflammatory stress in atherosclerosis, as well as the role of endothelial dysfunction in local and systemic manifestations of low-grade inflammation. We also present the features of immune mechanisms in the development of productive inflammation in stable and unstable plaques, along with their similarities and differences compared to canonical inflammation. There are numerous factors that act as inducers of the inflammatory process in atherosclerosis, including vascular endothelium aging, metabolic dysfunctions, autoimmune, and in some cases, infectious damage factors. Life-critical complications of atherosclerosis, such as cardiogenic shock and severe strokes, are associated with the development of acute systemic hyperinflammation. Additionally, critical atherosclerotic ischemia of the lower extremities induces paracoagulation and the development of chronic systemic inflammation. Conversely, sepsis, other critical conditions, and severe systemic chronic diseases contribute to atherogenesis. In summary, atherosclerosis can be characterized as an independent form of inflammation, sharing similarities but also having fundamental differences from low-grade inflammation and various variants of canonical inflammation (classic vasculitis).

Characteristic submucosal alteration in biliary carcinogenesis of pancreaticobiliary maljunction with a focus on inflammasome activation

BACKGROUND

This study investigated submucosal alterations in biliary carcinogenesis of pancreaticobiliary maljunction (PBM).

METHODS

Thirty-three patients with PBM (including seven with gallbladder [GB] cancer), four with neither biliary tract cancer nor PBM who underwent pancreaticoduodenectomy (controls), and seven with chronic cholecystitis without PBM were enrolled. Protein expression of α-smooth muscle actin (αSMA), CD68, and CD204 in the GB lamina propria and that of NLRP3 and caspase 1 in the GB epithelium and lamina propria were examined.

RESULTS

Compared with the control and cholecystitis groups, αSMA expression was higher in the cancerous part (stroma) of the GB in patients with GB cancer + PBM and in the lamina propria of patients with PBM. The CD204/CD68 ratio in the lamina propria was higher in the PBM group than in the control and cholecystitis groups. NLRP3 and caspase 1 expression in both the lamina propria and epithelium was higher in the PBM than control group. In the PBM group, NLRP3- and caspase 1-positive cells in the lamina propria were located near the epithelium.

CONCLUSION

Activated fibroblasts and M2 macrophages in the GB lamina propria may be associated with biliary carcinogenesis of PBM, possibly through inflammasome activation.

The role of macrophages in the tumor microenvironment and tumor metabolism

The complexity and plasticity of the tumor microenvironment (TME) make it difficult to fully understand the intratumoral regulation of different cell types and their activities. Macrophages play a crucial role in the signaling dynamics of the TME. Among the different subtypes of macrophages, tumor-associated macrophages (TAMs) are often associated with poor prognosis, although some subtypes of TAMs can at the same time improve treatment responsiveness and lead to favorable clinical outcomes. TAMs are key regulators of cancer cell proliferation, metastasis, angiogenesis, extracellular matrix remodeling, tumor metabolism, and importantly immunosuppression in the TME by modulating various chemokines, cytokines, and growth factors. TAMs have been identified as a key contributor to resistance to chemotherapy and cancer immunotherapy. In this review article, we aim to discuss the mechanisms by which TAMs regulate innate and adaptive immune signaling in the TME and summarize recent preclinical research on the development of therapeutics targeting TAMs and tumor metabolism.

Targeting Glioblastoma-Associated Macrophages for Photodynamic Therapy Using AGuIX®-Design Nanoparticles

Glioblastoma (GBM) is the most difficult brain cancer to treat, and photodynamic therapy (PDT) is emerging as a complementary approach to improve tumor eradication. Neuropilin-1 (NRP-1) protein expression plays a critical role in GBM progression and immune response. Moreover, various clinical databases highlight a relationship between NRP-1 and M2 macrophage infiltration. In order to induce a photodynamic effect, multifunctional AGuIX^®-design nanoparticles were used in combination with a magnetic resonance imaging (MRI) contrast agent, as well as a porphyrin as the photosensitizer molecule and KDKPPR peptide ligand for targeting the NRP-1 receptor. The main objective of this study was to characterize the impact of macrophage NRP-1 protein expression on the uptake of functionalized AGuIX^®-design nanoparticles in vitro and to describe the influence of GBM cell secretome post-PDT on the polarization of macrophages into M1 or M2 phenotypes. By using THP-1 human monocytes, successful polarization into the macrophage phenotypes was argued via specific morphological traits, discriminant nucleocytoplasmic ratio values, and different adhesion abilities based on real-time cell impedance measurements. In addition, macrophage polarization was confirmed via the transcript-level expression of TNFα, CXCL10, CD-80, CD-163, CD-206, and CCL22 markers. In relation to NRP-1 protein over-expression, we demonstrated a three-fold increase in functionalized nanoparticle uptake for the M2 macrophages compared to the M1 phenotype. The secretome of the post-PDT GBM cells led to nearly a three-fold increase in the over-expression of TNFα transcripts, confirming the polarization to the M1 phenotype. The in vivo relationship between post-PDT efficiency and the inflammatory effects points to the extensive involvement of macrophages in the tumor zone.

Molybdenum and cadmium co-exposure promotes M1 macrophage polarization through oxidative stress-mediated inflammatory response and induces pulmonary fibrosis in Shaoxing ducks (Anas platyrhyncha)

High molybdenum (Mo) and cadmium (Cd) are harmful to the body, but pulmonary toxicity induced by Mo and Cd co-exposure is unknown. To assess the combined impacts of Mo and Cd on fibrosis through M1 polarization in the lung of ducks, 80 healthy 8-day-old Shaoxing ducks (Anas platyrhyncha) were randomly assigned to 4 groups and fed with containing unequal doses of Mo or/and Cd diet. Lung tissues were collected on the 16th week. Results indicated that Mo or/and Cd significantly increased their contents in the lungs, and led to trace elements disorder and histological abnormality, and oxidative stress accompanied by promoting contents of H₂ O₂ and MDA and decreasing activities of T-SOD, GSH-Px, and CAT, then activated the TLR4/NF-κB/NLRP3 pathway accompanied by upregulating Caspase-1, ASC, IL-18, IL-1β, TLR4, NF-κB, and NLRP3 expression levels, and disrupted M1/M2 balance to divert toward M1, which evoked the TGF-β/Smad2/3-mediated fibrosis by elevating TGF-β1, Smad2, Smad3, COL1A1, α-SMA, and MMP2 expression levels, and decreasing Smad7 and TIMP2 expression levels. The changes of the combined group were most obvious. To sum up, the research demonstrated that Mo or/and Cd may cause macrophages to polarize toward M1 by oxidative stress-mediated the TLR4/NF-κB/NLRP3 pathway, then result in fibrosis through the TGF-β1/Smad2/3 pathway in duck lungs. Mo and Cd may worsen lung damage.

Influence of the Immune Microenvironment Provided by Implanted Biomaterials on the Biological Properties of Masquelet-Induced Membranes in Rats: Metakaolin as an Alternative Spacer

Macrophages play a key role in the inflammatory phase of wound repair and foreign body reactions-two important processes in the Masquelet-induced membrane technique for extremity reconstruction. The macrophage response depends largely on the nature of the biomaterials implanted. However, little is known about the influence of the macrophage microenvironment on the osteogenic properties of the induced membrane or subsequent bone regeneration. We used metakaolin, an immunogenic material, as an alternative spacer to standard polymethylmethacrylate (PMMA) in a Masquelet model in rats. Four weeks after implantation, the PMMA- and metakaolin-induced membranes were harvested, and their osteogenic properties and macrophage microenvironments were investigated by histology, immunohistochemistry, mass spectroscopy and gene expression analysis. The metakaolin spacer induced membranes with higher levels of two potent pro-osteogenic factors, transforming growth factor-β (TGF-β) and bone morphogenic protein-2 (BMP-2). These alternative membranes thus had greater osteogenic activity, which was accompanied by a significant expansion of the total macrophage population, including both the M1-like and M2-like subtypes. Microcomputed tomographic analysis showed that metakaolin-induced membranes supported bone regeneration more effectively than PMMA-induced membranes through better callus properties (+58%), although this difference was not significant. This study provides the first evidence of the influence of the immune microenvironment on the osteogenic properties of the induced membranes.

Applications of machine learning in tumor-associated macrophages

Evaluation of tumor-host interaction and intratumoral heterogeneity in the tumor microenvironment (TME) is gaining increasing attention in modern cancer therapies because it can reveal unique information about the tumor status. As tumor-associated macrophages (TAMs) are the major immune cells infiltrating in TME, a better understanding of TAMs could help us further elucidate the cellular and molecular mechanisms responsible for cancer development. However, the high-dimensional and heterogeneous data in biology limit the extensive integrative analysis of cancer research. Machine learning algorithms are particularly suitable for oncology data analysis due to their flexibility and scalability to analyze diverse data types and strong computation power to learn underlying patterns from massive data sets. With the application of machine learning in analyzing TME, especially TAM’s traceable status, we could better understand the role of TAMs in tumor biology. Furthermore, we envision that the promotion of machine learning in this field could revolutionize tumor diagnosis, treatment stratification, and survival predictions in cancer research. In this article, we described key terms and concepts of machine learning, reviewed the applications of common methods in TAMs, and highlighted the challenges and future direction for TAMs in machine learning.

Interaction Between Intrinsic Renal Cells and Immune Cells in the Progression of Acute Kidney Injury

A growing number of studies have confirmed that immune cells play various key roles in the pathophysiology of acute kidney injury (AKI) development. After the resident immune cells and intrinsic renal cells are damaged by ischemia and hypoxia, drugs and toxins, more immune cells will be recruited to infiltrate through the release of chemokines, while the intrinsic cells promote macrophage polarity conversion, and the immune cells will promote various programmed deaths, phenotypic conversion and cycle arrest of the intrinsic cells, ultimately leading to renal impairment and fibrosis. In the complex and dynamic immune microenvironment of AKI, the bidirectional interaction between immune cells and intrinsic renal cells affects the prognosis of the kidney and the progression of fibrosis, and determines the ultimate fate of the kidney.

Dose-dependent immunomodulatory effects of metformin on human neonatal monocyte-derived macrophages

While the association of inflammation with bronchopulmonary dysplasia (BPD) has long been appreciated, M1 proinflammatory macrophage population is emerging as the key element in driving the BPD inflammatory environment. Previous study suggests that low-dose metformin elicits an anti-inflammatory response, possibly through modulating macrophages, to improve disease outcome in a rat BPD model. To investigate this concept further, we examined the dose-dependent immunomodulatory function of metformin directly on human macrophages derived from cord blood (CB) monocytes. We demonstrate that low-dose metformin promotes expansion of M2 anti-inflammatory macrophages, contrasted with high-dose treatment, which exacerbates inflammation by favoring M1 polarization and restricting M2 phenotype. These findings highlight that metformin hold immunomodulatory ability by regulating macrophage polarization in a dose-dependent manner, and only when applied at low dose, exhibiting potential for beneficial anti-inflammatory adjuvant in BPD setting.

Inflammation: A New Look at an Old Problem

Pro-inflammatory stress is inherent in any cells that are subject to damage or threat of damage. It is defined by a number of universal components, including oxidative stress, cellular response to DNA damage, unfolded protein response to mitochondrial and endoplasmic reticulum stress, changes in autophagy, inflammasome formation, non-coding RNA response, formation of an inducible network of signaling pathways, and epigenetic changes. The presence of an inducible receptor and secretory phenotype in many cells is the cause of tissue pro-inflammatory stress. The key phenomenon determining the occurrence of a classical inflammatory focus is the microvascular inflammatory response (exudation, leukocyte migration to the alteration zone). This same reaction at the systemic level leads to the development of life-critical systemic inflammation. From this standpoint, we can characterize the common mechanisms of pathologies that differ in their clinical appearance. The division of inflammation into alternative variants has deep evolutionary roots. Evolutionary aspects of inflammation are also described in the review. The aim of the review is to provide theoretical arguments for the need for an up-to-date theory of the relationship between key human pathological processes based on the integrative role of the molecular mechanisms of cellular and tissue pro-inflammatory stress.

Sirtuin 7 Deficiency Reduces Inflammation and Tubular Damage Induced by an Episode of Acute Kidney Injury

Acute kidney injury (AKI) is a public health problem worldwide. Sirtuins are a family of seven NAD+-dependent deacylases, Overexpression of Sirtuin 1, 3, and 5 protect against AKI. However, the role of Sirtuin 7 (Sirt7) in AKI is not known. Here, we analyzed how Sirt7 deficient mice (KO-Sirt7) were affected by AKI. As expected, wild-type and Sirt7 heterozygotes mice that underwent renal ischemia/reperfusion (IR) exhibited the characteristic hallmarks of AKI: renal dysfunction, tubular damage, albuminuria, increased oxidative stress, and renal inflammation. In contrast, the KO-Sirt7+IR mice were protected from AKI, exhibiting lesser albuminuria and reduction in urinary biomarkers of tubular damage, despite similar renal dysfunction. The renoprotection in the Sirt7-KO+IR group was associated with reduced kidney weight, minor expression of inflammatory cytokines and less renal infiltration of inflammatory cells. This anti-inflammatory effect was related to diminished p65 expression and in its active phosphorylation, as well as by a reduction in p65 nuclear translocation. Sirt7 deficient mice are protected from AKI, suggesting that this histone deacetylase promotes tubular damage and renal inflammation. Therefore, our findings indicate that Sirt7 inhibitors may be an attractive therapeutic target to reduce NFκB signaling.

Exosomes derived from inflammatory myoblasts promote M1 polarization and break the balance of myoblast proliferation/differentiation

BACKGROUND

Acute muscle injuries are one of the most common injuries in sports. Severely injured muscles are prone to re-injury due to fibrotic scar formation caused by prolonged inflammation. How to regulate inflammation and suppress fibrosis is the focus of promoting muscle healing. Recent studies have found that myoblasts and macrophages play important roles in the inflammatory phase following muscle injury; however, the crosstalk between these two types of cells in the inflammatory environment, particularly the exosome-related mechanisms, had not been well studied.

AIM

To evaluate the effects of exosomes from inflammatory C2C12 myoblasts (IF-C2C12-Exos) on macrophage polarization and myoblast proliferation/differentiation.

METHODS

A model of inflammation was established in vitro by lipopolysaccharide stimulation of myoblasts. C2C12-Exos were isolated and purified from the supernatant of myoblasts by gradient centrifugation. Multiple methods were used to identify the exosomes. Gradient concentrations of IF-C2C12-Exos were added to normal macrophages and myoblasts. PKH67 fluorescence tracing was used to identify the interaction between exosomes and cells. Microscopic morphology, Giemsa stain, and immunofluorescence were carried out for histological analysis. Additionally, ELISA assays, flow cytometry, and western blot were conducted to analyze molecular changes. Moreover, myogenic proliferation was assessed by the BrdU test, scratch assay, and CCK-8 assay.

RESULTS

We found that the PKH-67-marked C2C12-Exos can be endocytosed by both macrophages and myoblasts. IF-C2C12-Exos induced M1 macrophage polarization and suppressed the M2 phenotype in vitro. In addition, these exosomes also stimulated the inflammatory reactions of macrophages. Furthermore, we demonstrated that IF-C2C12-Exos disrupted the balance of myoblast proliferation/differentiation, leading to enhanced proliferation and suppressed fibrogenic/myogenic differentiation.

CONCLUSION

IF-C2C12-Exos can induce M1 polarization, resulting in a sustained and aggravated inflammatory environment that impairs myoblast differentiation, and leads to enhanced myogenic proliferation. These results demonstrate why prolonged inflammation occurs after acute muscle injury and provide a new target for the regulation of muscle regeneration.

Is the Macrophage Phenotype Determinant for Fibrosis Development?

Fibrosis is a pathophysiological process of wound repair that leads to the deposit of connective tissue in the extracellular matrix. This complication is mainly associated with different pathologies affecting several organs such as lung, liver, heart, kidney, and intestine. In this fibrotic process, macrophages play an important role since they can modulate fibrosis due to their high plasticity, being able to adopt different phenotypes depending on the microenvironment in which they are found. In this review, we will try to discuss whether the macrophage phenotype exerts a pivotal role in the fibrosis development in the most important fibrotic scenarios.

Properties of macrophages and lymphocytes appearing in rat renal fibrosis followed by repeated injection of cisplatin

Properties of macrophages and lymphocytes appearing in renal fibrosis remains to be investigated. F344 rats were injected once a week with cisplatin (2 mg/kg body weight) for 8 weeks and examined at post-final injection weeks 1, 3, 6, 9, and 12. Rats developed progressive renal fibrosis at weeks 1 to 6 as fibrosis-progress phase, and subsequent amelioration at weeks 9 and 12. CD68+ M1-macrophages and major histocompatibility complex (MHC) class II+ macrophages remarkably increased persistently, whereas CD163+ M2-macrophages slightly increased. MHC class II+/CD68+ and MHC class II+/CD163+ macrophages were present, indicating that MHC class II+ macrophages might have both functions of M1- and M2-macrophages. In the fibrosis-progress phase, interleukin (IL)-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ for M1-factors, and transforming growth factor (TGF)-β1 and IL-10 for M2-factors tended to increase; tissue injury by M1 and fibrosis by M2 might have occurred simultaneously. Lots of CD4+ and CD8+ T cells appeared in close relation with MHC class II+ macrophages, and mainly CD4+ T cells formed aggregations. In the lymphocyte aggregates collected by laser microdissection, expression of IL-17A (for Th17 cells) and forkhead box P3 (FoxP3) (for Treg) significantly increased at weeks 1 and 6, respectively; presumably, Th17 cells might be involved in tissue injury, whereas Treg might be related to fibrosis amelioration. These results suggested that macrophages and T cells may contribute interrelatedly to renal fibrosis.

Subacute cadmium exposure promotes M1 macrophage polarization through oxidative stress-evoked inflammatory response and induces porcine adrenal fibrosis

Cadmium (Cd) is a widely distributed environmental pollutant with immunotoxicity and endocrine toxicity. M1/M2 macrophages participate in the immune response and exert an essential influence on fibrosis. Nevertheless, whether Cd can induce porcineadrenal fibrosis by affecting the polarization of M1/M2 macrophages and its potential regulatory mechanism have not been explored. We added 20 mg/kg CdCl₂ to the pig diet for 40 days to investigate the fibrogenic effect of subacute Cd exposure on the adrenal gland. The results indicated that the ACTH and CORT in serum were decreased by 15.26 % and 21.99 %, respectively. The contents of adrenal mineral elements Cd, Cr, Mn were increased up to 34, 1.93, 1.42 folds and Co, Zn, Sn were reduced by 21.57 %, 20.52 %, 15.75 %. Concurrently, the pro-oxidative indicators (LPO, MDA and H₂O₂) were increased by 1.85, 2.20, 2.77 folds and 3.60, 11.15, 4.11 folds upregulated mRNA levels of TLR4, NF-κB, NLRP3 were observed. Subsequently, the expression of M1 macrophages polarization markers (IL-6, iNOS, TNF-α, CCL2 and CXCL9) were raised by 2.03, 2.30, 2.35, 1.58, 1.56 folds, while M2 macrophages (IL-4, CCL24, Arg1, IL-10, MRC1) showed a 62.34 %, 31.88 %, 50.26 %, 74.00 %, 69.34 % downregulation. The expression levels of AMPK subunits and genes related to glycolysis, oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) were also markedly increased. Additionally, the expression level of TGF-β1, Smad2/3 and downstream pro-fibrotic markers was obviously upregulated. Taken together, we conclude that Cd activates the oxidative stress-mediated TLR4/NF-κB/NLRP3 inflammatory signal transduction, leading to porcine adrenal fibrosis by promoting macrophage polarization toward M1.

Local Inflammatory Response after Intramuscularly Implantation of Anti-Adhesive Plasma-Fluorocarbon-Polymer Coated Ti6AI4V Discs in Rats

Orthopaedic implants and temporary osteosynthesis devices are commonly based on Titanium (Ti). For short-term devices, cell-material contact should be restricted for easy removal after bone healing. This could be achieved with anti-adhesive plasma-fluorocarbon-polymer (PFP) films created by low-temperature plasma processes. Two different PFP thin film deposition techniques, microwave (MW) and radiofrequency (RF) discharge plasma, were applied to receive smooth, hydrophobic surfaces with octafluoropropane (C₃F₈) or hexafluorohexane (C₆F₆) as precursors. This study aimed at examining the immunological local tissue reactions after simultaneous intramuscular implantation of four different Ti samples, designated as MW-C₃F₈, MW-C₆F₆, RF-C₃F₈ and Ti-controls, in rats. A differentiated morphometric evaluation of the inflammatory reaction was conducted by immunohistochemical staining of CD68+ macrophages, CD163+ macrophages, MHC class II-positive cells, T lymphocytes, CD25+ regulatory T lymphocytes, NK cells and nestin-positive cells in cryosections of surrounding peri-implant tissue. Tissue samples were obtained on days 7, 14 and 56 for investigating the acute and chronical inflammation (n = 8 rats/group). Implants with a radiofrequency discharge plasma (RF-C₃F₈) coating exhibited a favorable short- and long-term immune/inflammatory response comparable to Ti-controls. This was also demonstrated by the significant decrease in pro-inflammatory CD68+ macrophages, possibly downregulated by significantly increasing regulatory T lymphocytes.

Role of Macrophages and Related Cytokines in Kidney Disease

Inflammation is a key characteristic of kidney disease, but this immune response is two-faced. In the acute phase of kidney injury, there is an activation of the immune cells to fight against the insult, contributing to kidney repair and regeneration. However, in chronic kidney diseases (CKD), immune cells that infiltrate the kidney play a deleterious role, actively participating in disease progression, and contributing to nephron loss and fibrosis. Importantly, CKD is a chronic inflammatory disease. In early CKD stages, patients present sub-clinical inflammation, activation of immune circulating cells and therefore, anti-inflammatory strategies have been proposed as a common therapeutic target for renal diseases. Recent studies have highlighted the plasticity of immune cells and the complexity of their functions. Among immune cells, monocytes/macrophages play an important role in all steps of kidney injury. However, the phenotype characterization between human and mice immune cells showed different markers; therefore the extrapolation of experimental studies in mice could not reflect human renal diseases. Here we will review the current information about the characteristics of different macrophage phenotypes, mainly focused on macrophage-related cytokines, with special attention to the chemokine CCL18, and its murine functional homolog CCL8, and the macrophage marker CD163, and their role in kidney pathology.

Immunophenotypic analysis of the distribution of hepatic macrophages, lymphocytes and hepatic stellate cells in the adult rat liver

The liver consists of parenchymal hepatocytes and non-parenchymal cells. Non-parenchymal cells, Kupffer cells, hepatic stellate cells and cholangiocytes have crucial roles in liver homeostasis and liver pathology. To establish baseline data, this study investigated immunohistochemically the distribution of non-parenchymal cells in perivenular areas (PV), periportal areas (PP) and Glisson's sheath (GS) of adult rat liver. Liver tissues were collected from the left lateral lobe of rats. CD163-positive macrophages were seen along the sinusoid of PV and PP areas, indicating Kupffer cells. Double immunofluorescence showed, Kupffer cells partly co-expressed CD68 and MHC class II antigens in the liver. The numbers of Kupffer cells were significantly high in PP areas as compared with PV or GS areas. CD68-positive exudative macrophages were highly localized in PP and GS areas and a comparatively low PV area. MHC class II-positive dendritic cells (activated macrophages) were localized mainly in GS. Granzyme B-positive NK cells were mainly localized in the Glisson's sheath. CD3-positive T cells and CD20-positive B cells were distributed along the sinusoids of the PP and PV areas of hepatic lobules. Vimentin and glial fibrillary acidic protein (GFAP)-positive hepatic stellate cells were localized along sinusoids in the hepatic lobules of the liver. Cholangiocytes reacting to cytokeratin 19 were seen on interlobular bile ducts in Glisson's sheath of the liver. This study shows that heterogeneous macrophage populations, liver-resident lymphocytes and hepatic stellate cells localized in PP and PV areas or GS areas of the liver with cells specific patterns.