Decellularized Extracellular Matrix: The Role of This Complex Biomaterial in Regeneration.

Organ transplantation is understood as a technique where an organ from a donor patient is transferred to a recipient patient. This practice gained strength in the 20th century and ensured advances in areas of knowledge such as immunology and tissue engineering. The main problems that comprise the practice of transplants involve the demand for viable organs and immunological aspects related to organ rejection. In this review, we address advances in tissue engineering for reversing the current challenges of transplants, focusing on the possible use of decellularized tissues in tissue engineering. We address the interaction of acellular tissues with immune cells, especially macrophages and stem cells, due to their potential use in regenerative medicine. Our goal is to exhibit data that demonstrate the use of decellularized tissues as alternative biomaterials that can be applied clinically as partial or complete organ substitutes.

Experimentally exposed toxic effects of long-term exposure to environmentally relevant concentrations of CIP in males and females of the silver catfish Rhamdia quelen.

Ciprofloxacin (CIP) is an antibiotic commonly used in human and veterinary medicine. It is present in the aquatic environment, but we still know very little about its effect on non-targeted organisms. This study aimed to evaluate the effects of long-term exposure to environmental CIP concentrations (1, 10, and 100 µg.L-1) in males and females of Rhamdia quelen. After 28 days of exposure, we collected the blood for the analysis of hematological and genotoxic biomarkers. Additionally, we measured 17 ß-estradiol and 11 keto-testosterone levels. After the euthanasia, we collected the brain and the hypothalamus to analyze acetylcholinesterase (AChE) activity and neurotransmitters, respectively. The liver and gonads were assessed for biochemical, genotoxic, and histopathological biomarkers. At 100 µg.L-1 CIP, we observed genotoxicity in the blood, nuclear morphological changes, apoptosis, leukopenia, and a reduction of AChE in the brain. In the liver was observed oxidative stress and apoptosis. At 10 µg.L-1 CIP, leukopenia, morphological changes, and apoptosis were presented in the blood and a reduction of AChE in the brain. Apoptosis, leukocyte infiltration, steatosis, and necrosis occurred in the liver. Even at the lowest concentration (1 µg.L-1), adverse effects such as erythrocyte and liver genotoxicity, hepatocyte apoptosis, oxidative stress, and a decrease in somatic indexes were observed. The results showed the importance of monitoring CIP concentrations in the aquatic environment that cause sublethal effects on fish.

A novel insight on SARS-CoV-2 S-derived fragments in the control of the host immunity.

Despite all efforts to combat the pandemic of COVID-19, we are still living with high numbers of infected persons, an overburdened health care system, and the lack of an effective and definitive treatment. Understanding the pathophysiology of the disease is crucial for the development of new technologies and therapies for the best clinical management of patients. Since the manipulation of the whole virus requires a structure with an adequate level of biosafety, the development of alternative technologies, such as the synthesis of peptides from viral proteins, is a possible solution to circumvent this problem. In addition, the use and validation of animal models is of extreme importance to screen new drugs and to compress the organism's response to the disease. Peptides derived from recombinant S protein from SARS-CoV-2 were synthesized and validated by in silico, in vitro and in vivo methodologies. Macrophages and neutrophils were challenged with the peptides and the production of inflammatory mediators and activation profile were evaluated. These peptides were also inoculated into the swim bladder of transgenic zebrafish larvae at 6 days post fertilization (dpf) to mimic the inflammatory process triggered by the virus, which was evaluated by confocal microscopy. In addition, toxicity and oxidative stress assays were also developed. In silico and molecular dynamics assays revealed that the peptides bind to the ACE2 receptor stably and interact with receptors and adhesion molecules, such as MHC and TCR, from humans and zebrafish. Macrophages stimulated with one of the peptides showed increased production of NO, TNF-α and CXCL2. Inoculation of the peptides in zebrafish larvae triggered an inflammatory process marked by macrophage recruitment and increased mortality, as well as histopathological changes, similarly to what is observed in individuals with COVID-19. The use of peptides is a valuable alternative for the study of host immune response in the context of COVID-19. The use of zebrafish as an animal model also proved to be appropriate and effective in evaluating the inflammatory process, comparable to humans.

Genetic and Epigenetic Regulation of the Innate Immune Response to Gout.

Gout is a disease caused by uric acid (UA) accumulation in the joints, causing inflammation. Two UA forms - monosodium urate (MSU) and soluble uric acid (sUA) have been shown to interact physically with inflammasomes, especially with the nod-like receptor (NLR) family pyrin domain containing 3 (NLRP3), albeit the role of the immune response to UA is poorly understood, given that asymptomatic hyperuricemia does also exist. Macrophage phagocytosis of UA activate NLRP3, lead to cytokines release, and ultimately, lead to chemoattract neutrophils and lymphocytes to the gout flare joint spot. Genetic variants of inflammasome genes and of genes encoding their molecular partners may influence hyperuricemia and gout susceptibility, while also influencing other comorbidities such as metabolic syndrome and cardiovascular diseases. In this review, we summarize the inflammatory responses in acute and chronic gout, specifically focusing on innate immune cell mechanisms and genetic and epigenetic characteristics of participating molecules. Unprecedently, a novel UA binding protein - the neuronal apoptosis inhibitor protein (NAIP) - is suggested as responsible for the asymptomatic hyperuricemia paradox.Abbreviation: ß2-integrins: leukocyte-specific adhesion molecules; ABCG2: ATP-binding cassete family/breast cancer-resistant protein; ACR: American college of rheumatology; AIM2: absent in melanoma 2, type of pattern recognition receptor; ALPK1: alpha-protein kinase 1; ANGPTL2: angiopoietin-like protein 2; ASC: apoptosis-associated speck-like protein; BIR: baculovirus inhibitor of apoptosis protein repeat; BIRC1: baculovirus IAP repeat-containing protein 1; BIRC2: baculoviral IAP repeat-containing protein 2; C5a: complement anaphylatoxin; cAMP: cyclic adenosine monophosphate; CARD: caspase activation and recruitment domains; CARD8: caspase recruitment domain-containing protein 8; CASP1: caspase 1; CCL3: chemokine (C-C motif) ligand 3; CD14: cluster of differentiation 14; CD44: cluster of differentiation 44; Cg05102552: DNA-methylation site, usually cytosine followed by guanine nucleotides; contains arbitrary identification code; CIDEC: cell death-inducing DNA fragmentation factor-like effector family; CKD: chronic kidney disease; CNV: copy number variation; CPT1A: carnitine palmitoyl transferase - type 1a; CXCL1: chemokine (CXC motif) ligand 1; DAMPs: damage associated molecular patterns; DC: dendritic cells; DNMT(1): maintenance DNA methyltransferase; eQTL: expression quantitative trait loci; ERK1: extracellular signal-regulated kinase 1; ERK2: extracellular signal-regulated kinase 2; EULAR: European league against rheumatism; GMCSF: granulocyte-macrophage colony-stimulating factor; GWAS: global wide association studies; H3K27me3: tri-methylation at the 27th lysine residue of the histone h3 protein; H3K4me1: mono-methylation at the 4th lysine residue of the histone h3 protein; H3K4me3: tri-methylation at the 4th lysine residue of the histone h3 protein; HOTAIR: human gene located between hoxc11 and hoxc12 on chromosome 12; IκBα: cytoplasmatic protein/Nf-κb transcription inhibitor; IAP: inhibitory apoptosis protein; IFNγ: interferon gamma; IL-1ß: interleukin 1 beta; IL-12: interleukin 12; IL-17: interleukin 17; IL18: interleukin 18; IL1R1: interleukin-1 receptor; IL-1Ra: interleukin-1 receptor antagonist; IL-22: interleukin 22; IL-23: interleukin 23; IL23R: interleukin 23 receptor; IL-33: interleukin 33; IL-6: interleukin 6; IMP: inosine monophosphate; INSIG1: insulin-induced gene 1; JNK1: c-jun n-terminal kinase 1; lncRNA: long non-coding ribonucleic acid; LRR: leucine-rich repeats; miR: mature non-coding microRNAs measuring from 20 to 24 nucleotides, animal origin; miR-1: miR followed by arbitrary identification code; miR-145: miR followed by arbitrary identification code; miR-146a: miR followed by arbitrary identification code, "a" stands for mir family; "a" family presents similar mir sequence to "b" family, but different precursors; miR-20b: miR followed by arbitrary identification code; "b" stands for mir family; "b" family presents similar mir sequence to "a" family, but different precursors; miR-221: miR - followed by arbitrary identification code; miR-221-5p: miR followed by arbitrary identification code; "5p" indicates different mature miRNAs generated from the 5' arm of the pre-miRNA hairpin; miR-223: miR followed by arbitrary identification code; miR-223-3p: mir followed by arbitrary identification code; "3p" indicates different mature miRNAs generated from the 3' arm of the pre-miRNA hairpin; miR-22-3p: miR followed by arbitrary identification code, "3p" indicates different mature miRNAs generated from the 3' arm of the pre-miRNA hairpin; MLKL: mixed lineage kinase domain-like pseudo kinase; MM2P: inductor of m2-macrophage polarization; MSU: monosodium urate; mTOR: mammalian target of rapamycin; MyD88: myeloid differentiation primary response 88; n-3-PUFAs: n-3-polyunsaturated fatty-acids; NACHT: acronym for NAIP (neuronal apoptosis inhibitor protein), C2TA (MHC class 2 transcription activator), HET-E (incompatibility locus protein from podospora anserina) and TP1 (telomerase-associated protein); NAIP: neuronal apoptosis inhibitory protein (human); Naip1: neuronal apoptosis inhibitory protein type 1 (murine); Naip5: neuronal apoptosis inhibitory protein type 5 (murine); Naip6: neuronal apoptosis inhibitory protein type 6 (murine); NBD: nucleotide-binding domain; Nek7: smallest NIMA-related kinase; NET: neutrophil extracellular traps; Nf-κB: nuclear factor kappa-light-chain-enhancer of activated b cells; NFIL3: nuclear-factor, interleukin 3 regulated protein; NIIMA: network of immunity in infection, malignancy, and autoimmunity; NLR: nod-like receptor; NLRA: nod-like receptor NLRA containing acidic domain; NLRB: nod-like receptor NLRA containing BIR domain; NLRC: nod-like receptor NLRA containing CARD domain; NLRC4: nod-like receptor family CARD domain containing 4; NLRP: nod-like receptor NLRA containing PYD domain; NLRP1: nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 1; NLRP12: nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 12; NLRP3: nod-like receptor family pyrin domain containing 3; NOD2: nucleotide-binding oligomerization domain; NRBP1: nuclear receptor-binding protein; Nrf2: nuclear factor erythroid 2-related factor 2; OR: odds ratio; P2X: group of membrane ion channels activated by the binding of extracellular; P2X7: p2x purinoceptor 7 gene; p38: member of the mitogen-activated protein kinase family; PAMPs: pathogen associated molecular patters; PBMC: peripheral blood mononuclear cells; PGGT1B: geranylgeranyl transferase type-1 subunit beta; PHGDH: phosphoglycerate dehydrogenase; PI3-K: phospho-inositol; PPARγ: peroxisome proliferator-activated receptor gamma; PPARGC1B: peroxisome proliferative activated receptor, gamma, coactivator 1 beta; PR3: proteinase 3 antigen; Pro-CASP1: inactive precursor of caspase 1; Pro-IL1ß: inactive precursor of interleukin 1 beta; PRR: pattern recognition receptors; PYD: pyrin domain; RAPTOR: regulatory associated protein of mTOR complex 1; RAS: renin-angiotensin system; REDD1: regulated in DNA damage and development 1; ROS: reactive oxygen species; rs000*G: single nuclear polymorphism, "*G" is related to snp where replaced nucleotide is guanine, usually preceded by an id number; SLC2A9: solute carrier family 2, member 9; SLC7A11: solute carrier family 7, member 11; SMA: smooth muscular atrophy; Smac: second mitochondrial-derived activator of caspases; SNP: single nuclear polymorphism; Sp3: specificity protein 3; ST2: serum stimulation-2; STK11: serine/threonine kinase 11; sUA: soluble uric acid; Syk: spleen tyrosine kinase; TAK1: transforming growth factor beta activated kinase; Th1: type 1 helper T cells; Th17: type 17 helper T cells; Th2: type 2 helper T cells; Th22: type 22 helper T cells; TLR: tool-like receptor; TLR2: toll-like receptor 2; TLR4: toll-like receptor 4; TNFα: tumor necrosis factor alpha; TNFR1: tumor necrosis factor receptor 1; TNFR2: tumor necrosis factor receptor 2; UA: uric acid; UBAP1: ubiquitin associated protein; ULT: urate-lowering therapy; URAT1: urate transporter 1; VDAC1: voltage-dependent anion-selective channel 1.

Evaluation of the effects of Loxosceles intermedia's venom in zebrafish.

The zebrafish is an animal model of increasing use in many biomedical fields of study, including toxicology, inflammation, and tissue regeneration. In this paper, we have investigated the inflammatory effects of Loxosceles intermedia's venom (LIV) on zebrafish, as well as the effects of Maresin 2 (Mar2) and Resolvin D5 (RvD5), two specialized pro-resolving mediators (SPMs), in the context of tissue regeneration after fin fold amputation. Furthermore, increasing concentrations of LIV (250-2000 ng) were assayed for their haemolytic effects in vitro, and, afterwards, the same concentrations were evaluated in vivo, when injected intraperitoneally. LIV caused haemolysis in human red blood cells (RBCs), but not in zebrafish RBCs. The survival curve was also not altered by LIV injection, regardless of venom dosage. Histological analysis of renal and hepatic tissues, as well as the whole animal, revealed no pathological differences between LIV-injected and PBS-injected groups. Fin fold regeneration was not altered between LIV-injected and control groups, nor in the presence of MaR2 and RvD5. Results of swimming behavioral analysis also did not differ between groups. Moreover, in silico data indicated differences between human and zebrafish cell membrane lipid constitutions, such as in phospholipases D preferred substrates, that could lead to the protection of zebrafish against LIV. Although our data implies that zebrafish cannot be used as a toxicological model for LIV studies, the absence of observed toxicological effects paves the way for the comprehension of the venom's mechanism of action in mammals and the fundamental evolutionary processes involved.

The dual effect of acetate on microglial TNF-α production.

INTRODUCTION: Short-Chain Fatty Acids (SCFA) are products of intestinal microbial metabolism that can reach the brain and alter microglia in health and disease contexts. However, data are conflicting on the effect of acetate, the most abundant SCFA in the blood, in these cells. OBJECTIVE: The authors aimed to investigate acetate as a modulator of the inflammatory response in microglia stimulated with LPS. METHOD: The authors used an immortalized cell line, C8-B4, and primary cells for in vitro treatments with acetate and LPS. Cell viability was analyzed by MTT, cytokine by RT-PCR, ELISA, and flow cytometry. The authors also performed in vivo and in silico analyses to study the role of acetate and the TNF-α contribution to the development of Experimental Autoimmune Encephalomyelitis (EAE). RESULTS: Acetate co-administered with LPS was able to exacerbate the production of pro-inflammatory cytokines at gene and protein levels in cell lines and primary culture of microglia. However, the same effects were not observed when acetate was administered alone or as pretreatment, prior to the LPS stimulus. Additionally, pharmacological inhibition of histone deacetylase concomitantly with acetate and LPS led to decreased TNF-α production. In silico analysis showed a crucial role of the TNF-α pathway in EAE development. Moreover, acetate administration in vivo during the initial phase of EAE led to a better disease outcome and reduced TNF-α production. CONCLUSION: Treatment with acetate was able to promote the production of TNF-α in a concomitant LPS stimulus of microglia. However, the immune modulation of microglia by acetate pretreatment may be a component in the generation of future therapies for neurodegenerative diseases.

Vitamin D and Omega-3 Polyunsaturated Fatty Acids in Type 1 Diabetes Modulation.

BACKGROUND: Type 1 diabetes (T1D) is a chronic autoimmune disease affecting people globally. Usually developed during childhood, T1D is characterized by the destruction of pancreatic ß-cells due to immune cell attack and the establishment of an inflammatory process. OBJECTIVE: The study aimed to investigate the effects of vitamin D through its nuclear receptor and the ω-3 polyunsaturated fatty acids (PUFAs) through their lipid derivatives in T1D modulation. Both components exert anti-inflammatory activity and act directly on cells of the immune system, attenuating the destruction of insulin-producing cells. Furthermore, they lead to a better glycemic level, reducing the need for insulin and a normal immune state, such as C-peptide maintenance. METHODS: Presently, our review highlights the significant studies that evaluated the supplementation of vitamin D and ω-3 PUFAs in humans and animal models in the modulation of T1D. CONCLUSION: The data collected suggests that supplementation can provide potential benefits, mainly when done early in the diagnosis, since it reduces the need for insulin and the risk of complications generated by the disease.

The dual effect of acetate on microglial TNF-α production

Abstract Introduction: Short-Chain Fatty Acids (SCFA) are products of intestinal microbial metabolism that can reach the brain and alter microglia in health and disease contexts. However, data are conflicting on the effect of acetate, the most abundant SCFA in the blood, in these cells. Objective: The authors aimed to investigate acetate as a modulator of the inflammatory response in microglia stimulated with LPS. Method: The authors used an immortalized cell line, C8-B4, and primary cells for in vitro treatments with acetate and LPS. Cell viability was analyzed by MTT, cytokine by RT-PCR, ELISA, and flow cytometry. The authors also performed in vivo and in silico analyses to study the role of acetate and the TNF-α contribution to the development of Experimental Autoimmune Encephalomyelitis (EAE). Results: Acetate co-administered with LPS was able to exacerbate the production of pro-inflammatory cytokines at gene and protein levels in cell lines and primary culture of microglia. However, the same effects were not observed when acetate was administered alone or as pretreatment, prior to the LPS stimulus. Additionally, pharmacological inhibition of histone deacetylase concomitantly with acetate and LPS led to decreased TNF-α production. In silico analysis showed a crucial role of the TNF-α pathway in EAE development. Moreover, acetate administration in vivo during the initial phase of EAE led to a better disease outcome and reduced TNF-α production. Conclusion: Treatment with acetate was able to promote the production of TNF-α in a concomitant LPS stimulus of microglia. However, the immune modulation of microglia by acetate pretreatment may be a component in the generation of future therapies for neurodegenerative diseases. HIGHLIGHTS Acetate was able to exacerbate the production of TNF-α in microglia. Acetate administered as pre-treatment to LPS acts as an anti-inflammatory. Histone deacetylase decreased TNF-α production in Acetate- and LPS-treated cells. Depending on the time of administration, Acetate modulates microglia's activation. Acetate may threaten neurodegenerative and neuropsychiatric diseases.

Distinct macrophage phenotypes and redox environment during the fin fold regenerative process in zebrafish.

In contrast to mammals, zebrafish (Danio rerio) has the ability to regenerate injured sites such as different tissues present in the fin. It is known that cells of the innate immune system play essential roles in regeneration; however, some aspects of the molecular mechanisms by which these cells orchestrate regeneration remain unknown. This study aimed to evaluate the infiltration dynamics of neutrophils and macrophages in the regenerative process of fin fold in regard to the influence of the redox environment and oxidative pathways. Fin fold amputation was performed on transgenic larvae for macrophage-expressed gene 1 (mpeg1), lysozyme (lyz), myeloperoxidase (mpo) and tumour necrosis factor alpha (TNFα) at 3 days post-fertilization, followed by confocal microscopy imaging and measurement of the activities of oxidant and antioxidant enzymes. We observed initially an increase in the number of neutrophils (lyz:DsRed+/mpx:GFP+) and then macrophages (mpeg1+) in the injury site followed by a decrease in neutrophils at 7 days post-amputation (dpa). Moreover, macrophages switch from a pro-inflammatory to an anti-inflammatory profile throughout the process, while the activity of superoxide dismutase (SOD) increased at 1 dpa and catalase (CAT) at 5 dpa. Higher levels of lipid peroxidation were also detected during regeneration. Despite oxidative stress, there is, therefore, an antioxidant response throughout the regeneration of the caudal fin. The present work can contribute to future studies on the development of cell therapies, achieving greater effectiveness in the treatment of diseases related to the formation of fibrotic tissue.

Sensing soluble uric acid by Naip1-Nlrp3 platform.

Uric acid (UA), a product of purine nucleotide degradation able to initiate an immune response, represents a breakpoint in the evolutionary history of humans, when uricase, the enzyme required for UA cleavage, was lost. Despite being inert in human cells, UA in its soluble form (sUA) can increase the level of interleukin-1ß (IL-1ß) in murine macrophages. We, therefore, hypothesized that the recognition of sUA is achieved by the Naip1-Nlrp3 inflammasome platform. Through structural modelling predictions and transcriptome and functional analyses, we found that murine Naip1 expression in human macrophages induces IL-1ß expression, fatty acid production and an inflammation-related response upon sUA stimulation, a process reversed by the pharmacological and genetic inhibition of Nlrp3. Moreover, molecular interaction experiments showed that Naip1 directly recognizes sUA. Accordingly, Naip may be the sUA receptor lost through the human evolutionary process, and a better understanding of its recognition may lead to novel anti-hyperuricaemia therapies.

Macrophage inflammatory state in Type 1 diabetes: triggered by NLRP3/iNOS pathway and attenuated by docosahexaenoic acid.

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by insulin-producing pancreatic ß-cell destruction and hyperglycemia. While monocytes and NOD-like receptor family-pyrin domain containing 3 (NLRP3) are associated with T1D onset and development, the specific receptors and factors involved in NLRP3 inflammasome activation remain unknown. Herein, we evaluated the inflammatory state of resident peritoneal macrophages (PMs) from genetically modified non-obese diabetic (NOD), NLRP3-KO, wild-type (WT) mice and in peripheral blood mononuclear cells (PBMCs) from human T1D patients. We also assessed the effect of docosahexaenoic acid (DHA) on the inflammatory status. Macrophages from STZ-induced T1D mice exhibited increased inflammatory cytokine/chemokine levels, nitric oxide (NO) secretion, NLRP3 and iNOS protein levels, and augmented glycolytic activity compared to control animals. In PMs from NOD and STZ-induced T1D mice, DHA reduced NO production and attenuated the inflammatory state. Furthermore, iNOS and IL-1ß protein expression levels and NO production were lower in the PMs from diabetic NLRP3-KO mice than from WT mice. We also observed increased IL-1ß secretion in PBMCs from T1D patients and immortalized murine macrophages treated with advanced glycation end products and palmitic acid. The present study demonstrated that the resident PMs are in a proinflammatory state characterized by increased NLRP3/iNOS pathway-mediated NO production, up-regulated proinflammatory cytokine/chemokine receptor expression and altered glycolytic activity. Notably, ex vivo treatment with DHA reverted the diabetes-induced changes and attenuated the macrophage inflammatory state. It is plausible that DHA supplementation could be employed as adjuvant therapy for treating individuals with T1D.

Myeloid Immune Cells CARrying a New Weapon Against Cancer.

Chimeric antigen receptor (CAR) engineering for T cells and natural killer cells (NK) are now under clinical evaluation for the treatment of hematologic cancers. Although encouraging clinical results have been reported for hematologic diseases, pre-clinical studies in solid tumors have failed to prove the same effectiveness. Thus, there is a growing interest of the scientific community to find other immune cell candidate to express CAR for the treatment of solid tumors and other diseases. Mononuclear phagocytes may be the most adapted group of cells with potential to overcome the dense barrier imposed by solid tumors. In addition, intrinsic features of these cells, such as migration, phagocytic capability, release of soluble factors and adaptive immunity activation, could be further explored along with gene therapy approaches. Here, we discuss the elements that constitute the tumor microenvironment, the features and advantages of these cell subtypes and the latest studies using CAR-myeloid immune cells in solid tumor models.

Macrophage inflammatory state in Type 1 diabetes: triggered by NLRP3/iNOS pathway and attenuated by docosahexaenoic acid

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by insulin-producing pancreatic β-cell destruction and hyperglycemia. While monocytes and NOD-like receptor family-pyrin domain containing 3 (NLRP3) are associated with T1D onset and development, the specific receptors and factors involved in NLRP3 inflammasome activation remain unknown. Herein, we evaluated the inflammatory state of resident peritoneal macrophages (PMs) from genetically modified non-obese diabetic (NOD), NLRP3-KO, wild-type (WT) mice and in peripheral blood mononuclear cells (PBMCs) from human T1D patients. We also assessed the effect of docosahexaenoic acid (DHA) on the inflammatory status. Macrophages from STZ-induced T1D mice exhibited increased inflammatory cytokine/chemokine levels, nitric oxide (NO) secretion, NLRP3 and iNOS protein levels, and augmented glycolytic activity compared to control animals. In PMs from NOD and STZ-induced T1D mice, DHA reduced NO production and attenuated the inflammatory state. Furthermore, iNOS and IL-1β protein expression levels and NO production were lower in the PMs from diabetic NLRP3-KO mice than from WT mice. We also observed increased IL-1β secretion in PBMCs from T1D patients and immortalized murine macrophages treated with advanced glycation end products and palmitic acid. The present study demonstrated that the resident PMs are in a proinflammatory state characterized by increased NLRP3/iNOS pathway-mediated NO production, up-regulated proinflammatory cytokine/chemokine receptor expression and altered glycolytic activity. Notably, ex vivo treatment with DHA reverted the diabetes-induced changes and attenuated the macrophage inflammatory state. It is plausible that DHA supplementation could be employed as adjuvant therapy for treating individuals with T1D.

The Role of NLRP3 Inflammasome Activation in the Epithelial to Mesenchymal Transition Process During the Fibrosis.

Fibrosis is considered a complex form of tissue damage commonly present in the end stage of many diseases. It is also related to a high percentage of death, whose predominant characteristics are an excessive and abnormal deposition of fibroblasts and myofibroblasts -derived extracellular matrix (ECM) components. Epithelial-to-mesenchymal transition (EMT), a process in which epithelial cells gradually change to mesenchymal ones, is a major contributor in the pathogenesis of fibrosis. The key mediator of EMT is a multifunctional cytokine called transforming growth factor-ß (TGF-ß) that acts as the main inducer of the ECM assembly and remodeling through the phosphorylation of Smad2/3, which ultimately forms a complex with Smad4 and translocates into the nucleus. On the other hand, the bone morphogenic protein-7 (BMP-7), a member of the TGF family, reverses EMT by directly counteracting TGF-ß induced Smad-dependent cell signaling. NLRP3 (NACHT, LRR, and PYD domains-containing protein 3), in turn, acts as cytosolic sensors of microbial and self-derived molecules and forms an immune complex called inflammasome in the context of inflammatory commitments. NLRP3 inflammasome assembly is triggered by extracellular ATP, reactive oxygen species (ROS), potassium efflux, calcium misbalance, and lysosome disruption. Due to its involvement in multiple diseases, NLRP3 has become one of the most studied pattern-recognition receptors (PRRs). Nevertheless, the role of NLRP3 in fibrosis development has not been completely elucidated. In this review, we described the relation of the previously mentioned fibrosis pathway with the NLRP3 inflammasome complex formation, especially EMT-related pathways. For now, it is suggested that the EMT happens independently from the oligomerization of the whole inflammasome complex, requiring just the presence of the NLRP3 receptor and the ASC protein to trigger the EMT events, and we will present different pieces of research that give controversial point of views.

The role of uric acid in inflammasome-mediated kidney injury.

PURPOSE OF REVIEW: Uric acid is produced after purine nucleotide degradation, upon xanthine oxidase catalytic action. In the evolutionary process, humans lost uricase, an enzyme that converts uric acid into allantoin, resulting in increased serum uric acid levels that may vary according to dietary ingestion, pathological conditions, and other factors. Despite the controversy over the inflammatory role of uric acid in its soluble form, crystals of uric acid are able to activate the NLRP3 inflammasome in different tissues. Uric acid, therefore, triggers hyperuricemic-related disease such as gout, metabolic syndrome, and kidney injuries. The present review provides an overview on the role of uric acid in the inflammasome-mediated kidney damage. RECENT FINDINGS: Hyperuricemia is present in 20-35% of patients with chronic kidney disease. However, whether this increased circulating uric acid is a risk factor or just a biomarker of renal and cardiovascular injuries has become a topic of intense discussion. Despite these conflicting views, several studies support the idea that hyperuricemia is indeed a cause of progression of kidney disease, with a putative role for soluble uric acid in activating renal NLRP3 inflammasome, in reprograming renal and immune cell metabolism and, therefore, in promoting kidney inflammation/injury. SUMMARY: Therapies aiming to decrease uric acid levels prevent renal NLRP3 inflammasome activation and exert renoprotective effects in experimental kidney diseases. However, further clinical studies are needed to investigate whether reduced circulating uric acid can also inhibit the inflammasome and be beneficial in human conditions.

Fecal IgA Levels and Gut Microbiota Composition Are Regulated by Invariant Natural Killer T Cells.

BACKGROUND: The gut microbiota is a key element to support host homeostasis and the development of the immune system. The relationship between the microbiota and immunity is a 2-way road, in which the microbiota contributes to the development/function of immune cells and immunity can affect the composition of microbes. In this context, natural killer T cells (NKT cells) are distinct T lymphocytes that play a role in gut immunity and are influenced by gut microbes. In our work, we investigated the involvement of invariant NKT cells (iNKT) in intestinal homeostasis. RESULTS: We found that iNKT-deficient mice (iNKT-KO) had reduced levels of fecal IgA and an altered composition of the gut microbiota, with increased Bacteroidetes. The absence of iNKT cells also affected TGF-ß1 levels and plasma cells, which were significantly reduced in knockout (KO) mice. In addition, when submitted to dextran sodium sulfate colitis, iNKT-KO mice had worsening of colitis when compared with wild-type (WT) mice. To further address iNKT cell contribution to intestinal homeostasis, we adoptively transferred iNKT cells to KO mice, and they were submitted to colitis. Transfer of iNKT cells improved colitis and restored fecal IgA levels and gut microbiota. CONCLUSIONS: Our results indicate that intestinal NKT cells are important modulators of intestinal homeostasis and that gut microbiota composition may be a potential target in the management of inflammatory bowel diseases.

NLRP3 gain-of-function in CD4+ T lymphocytes ameliorates experimental autoimmune encephalomyelitis.

NLRP3 inflammasome [NLR (nucleotide-binding domain, leucine-rich repeat containing protein) Pyrin-domain-containing 3 ] functions as an innate sensor of several PAMPs and DAMPs (pathogen- and damage-associated molecular patterns). It has been also reported as a transcription factor related to Th2 pattern, although its role in the adaptive immunity has been controversial, mainly because the studies were performed using gene deletion approaches. In the present study, we have investigated the NLRP3 gain-of-function in the context of encephalomyelitis autoimmune disease (EAE), considered to be a Th1- and Th17-mediated disease. We took advantage of an animal model with NLRP3 gain-of-function exclusively to T CD4+ lymphocytes (CD4CreNLRP3fl/fl). These mice presented reduced clinical score, accompanied by less infiltrating T CD4+ cells expressing both IFN-γ and IL-17 at the central nervous system (CNS) during the peak of the disease. However, besides NLRP3 gain-of-function in lymphocytes, these mice lack NLRP3 expression in non-T CD4+ cells. Therefore, in order to circumvent this deficiency, we transferred naive CD4+ T cells from WT, NLRP3-/- or CD4CreNLRP3fl/fl into Rag-1-/- mice and immunized them with MOG35-55 Likewise, the animals repopulated with CD4CreNLRP3fl/fl T CD4+ cells presented reduced clinical score and decreased IFN-γ production at the peak of the disease. Additionally, primary effector CD4+ T cells derived from these mice presented reduced glycolytic profile, a metabolic profile compatible with Th2 cells. Finally, naive CD4+ T cells from CD4CreNLRP3fl/fl mice under a Th2-related cytokine milieu cocktail exhibited in vitro an increased IL-4 and IL-13 production. Conversely, naive CD4+ T cells from CD4CreNLRP3fl/fl mice under Th1 differentiation produced less IFN-γ and T-bet. Altogether, our data evidence that the NLRP3 gain-of-function promotes a Th2-related response, a pathway that could be better explored in the treatment of multiple sclerosis.

Understanding the Metabolic Profile of Macrophages During the Regenerative Process in Zebrafish.

In contrast to mammals, lower vertebrates, including zebrafish (Danio rerio), have the ability to regenerate damaged or lost tissues, such as the caudal fin, which makes them an ideal model for tissue and organ regeneration studies. Since several diseases involve the process of transition between fibrosis and tissue regeneration, it is necessary to attain a better understanding of these processes. It is known that the cells of the immune system, especially macrophages, play essential roles in regeneration by participating in the removal of cellular debris, release of pro- and anti-inflammatory factors, remodeling of components of the extracellular matrix and alteration of oxidative patterns during proliferation and angiogenesis. Immune cells undergo phenotypical and functional alterations throughout the healing process due to growth factors and cytokines that are produced in the tissue microenvironment. However, some aspects of the molecular mechanisms through which macrophages orchestrate the formation and regeneration of the blastema remain unclear. In the present review, we outline how macrophages orchestrate the regenerative process in zebrafish and give special attention to the redox balance in the context of tail regeneration.

Protective role of NKT cells and macrophage M2-driven phenotype in bleomycin-induced pulmonary fibrosis.

Pulmonary fibrosis is a result of an abnormal wound healing in lung tissue triggered by an excessive accumulation of extracellular matrix proteins, loss of tissue elasticity, and debit of ventilatory function. NKT cells are a major source of Th1 and Th2 cytokines and may be crucial in the polarization of M1/M2 macrophages in pulmonary fibrogenesis. Although there appears to be constant scientific progress in that field, pulmonary fibrosis still exhibits no current cure. From these facts, we hypothesized that NKT cells could influence the development of pulmonary fibrosis via modulation of macrophage activation. Wild type (WT) and NKT type I cell-deficient mice (Jα18-/-) were subjected to the protocol of bleomycin-induced pulmonary fibrosis with or without treatment with NKT cell agonists α-galactosylceramide and sulfatide. The participation of different cell populations, collagen deposition, and protein levels of different cytokines involved in inflammation and fibrosis was evaluated. The results indicate a benign role of NKT cells in Jα18-/- mice and in wild-type α-galactosylceramide-sulfatide-treated groups. These animals presented lower levels of collagen deposition, fibrogenic molecules such as TGF-ß and vimentin and improved survival rates. In contrast, WT mice developed a Th2-driven response augmenting IL-4, 5, and 13 protein synthesis and increased collagen deposition. Furthermore, the arginase-1 metabolic pathway was downregulated in wild-type NKT-activated and knockout mice indicating lower activity of M2 macrophages in lung tissue. Hence, our data suggest that NKT cells play a protective role in this experimental model by down modulating the Th2 milieu, inhibiting M2 polarization and finally preventing fibrosis.