Avaliação dos níveis da citocina pró-inflamatória fator de necrose tumoral-α em pacientes com diabetes tipo 2 e sua relação com variações genéticas de enzimas antioxidantes e obesidade / Evaluation of proinflammatory cytokine tumor necrosis factor-α levels in obese vs nonobese patients with type 2 diabetes and their relationship to CAT C-262T polymorphism

Introdução: Diabetes tipo 2 (DM2) é um distúrbio multifatorial caracterizado pelo aumento dos níveis de radicais livres. Tanto o estresse oxidativo quanto a obesidade contribuem para um estado inflamatório da doença, principalmente pelo aumento da citocina TNF-α. Sabendo-se que a genética individual pode contribuir para o estresse oxidativo, o estudo avaliou o impacto das variações genéticas de enzimas antioxidantes C262T no gene CAT e polimorfismos nulos dos genes GSTM1 e GSTT1 nos níveis de TNF-α, assim como, avaliou se as variantes genéticas atuariam sinergicamente com a obesidade aumentando os níveis da citocina em diabéticos da Grande Vitória/ES, Brasil.Métodos: O polimorfismo no gene CAT foi avaliado pela técnica PCR/RFLP e nos genes GSTM1 e GSTT1 por PCR multiplex, em 56 pacientes, sendo 28 obesos e 28 não obesos. Níveis de TNF-α foram medidos pela técnica de ELISA sanduíche.Resultados: Frequências das variantes nulas de GSTM1 e GSTT1 foram 44,6% e 17,9%, respectivamente. As frequências genotípicas C262T-CAT foram 73,2%, 25% e 1,8% para homozigoto normal, heterozigoto e homozigoto polimórfico, respectivamente. Não houve associação entre genótipos polimórficos e aumento dos níveis de TNF-α, assim como, não foi demonstrado aumento significante da citocina quando avaliado o sinergismo entre obesidade e genética individual do paciente.Conclusão: Níveis de TNF-α não se elevam em diabéticos tipo 2 na presença dos polimorfismos nos genes CAT, GSTM1 e GSTT1, e a obesidade não atua no aumento dessa citocina na população estudada, separadamente ou em conjunto com a genética individual de variantes nos genes CAT, GSTM1 e GSTT1.

Introduction: Type 2 diabetes is a multifactorial disorder characterized by increased levels of free radicals. Both oxidative stress and obesity contribute to an inflammatory state of the disease, mainly by increasing the levels of the proinflammatory cytokine tumor necrosis factor-α (TNF-α). Considering that personal genetics may contribute to oxidative stress, this study assessed the impact of CAT C-262T polymorphism and GSTM1 and GSTT1 null polymorphisms on TNF-α levels in patients with type 2. diabetes. The study also evaluated whether the genetic variants act synergistically with obesity to increase TNF-α levels in patients with diabetes from Grande Vitória, Brazil.Methods: Fifty-six patients were included, of whom 28 were obese and 28 were nonobese. The CAT gene polymorphism was assessed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, whereas GSTM1 and GSTT1 polymorphisms were assessed using multiplex PCR. TNF-α levels were measured using the sandwich ELISA technique.Results: Frequencies of GSTM1 and GSTT1 null polymorphisms were 44.6% and 17.9%, respectively. The genotype frequencies of CATC-262T polymorphism were 73.2%, 25.0%, and 1.8% for normal homozygote, heterozygote, and polymorphic homozygote, respectively. Polymorphic genotypes were not associated with increased TNF-α levels, and there was no significant increase in TNF-α levels when evaluating the synergism between obesity and personal genetics.Conclusion: The presence of CAT, GSTM1, and GSTT1 gene polymorphisms was not associated with increased TNF-α levels in patients with type 2 diabetes. Obesity alone or combined with personal genetics of CAT, GSTM1, and GSTT1gene polymorphisms did not promote increased TNF-α levels in the study population.

Neuronal TNFα, Not α-Syn, Underlies PDD-Like Disease Progression in IFNß-KO Mice.

OBJECTIVE: Parkinson's disease (PD) manifests in motor dysfunction, non-motor symptoms, and eventual dementia (PDD). Neuropathological hallmarks include nigrostriatal neurodegeneration, Lewy body (LB) pathology, and neuroinflammation. Alpha-synuclein (α-syn), a primary component of LBs, is implicated in PD pathogenesis, accumulating, and aggregating in both familial and sporadic PD. However, as α-syn pathology is often comorbid with amyloid-beta (Aß) plaques and phosphorylated tau (pTau) tangles in PDD, it is still unclear whether α-syn is the primary cause of neurodegeneration in sporadic PDD. We aimed to determine how the absence of α-syn would affect PDD manifestation. METHODS: IFN-ß knockout (Ifnb-/- ) mice spontaneously develop progressive behavior abnormalities and neuropathology resembling PDD, notably with α-syn+ LBs. We generated Ifnb/Snca double knockout (DKO) mice and evaluated their behavior and neuropathology compared with wild-type (Wt), Ifnb-/- , and Snca-/- mice using immunohistochemistry, electron microscopy, immunoblots, qPCR, and modification of neuronal signaling. RESULTS: Ifnb/Snca DKO mice developed all clinical PDD-like behavioral manifestations induced by IFN-ß loss. Independently of α-syn expression, lack of IFN-ß alone induced Aß plaques, pTau tangles, and LB-like Aß+ /pTau+ inclusion bodies and neuroinflammation. IFN-ß loss caused significant elevated glial and neuronal TNF-α and neuronal TNFR1, associated with neurodegeneration. Restoring neuronal IFN-ß signaling or blocking TNFR1 rescued caspase 3/t-BID-mediated neuronal-death through upregulation of c-FLIPS and lowered intraneuronal Aß and pTau accumulation. INTERPRETATION: These findings increase our understanding of PD pathology and suggest that targeting α-syn alone is not sufficient to mitigate disease. Targeting specific aspects of neuroinflammation, such as aberrant neuronal TNF-α/TNFR1 or IFN-ß/IFNAR signaling, may attenuate disease. ANN NEUROL 2021;90:789-807.

Asymptomatic SARS-CoV-2 infection: is it all about being refractile to innate immune sensing of viral spare-parts?-Clues from exotic animal reservoirs.

A vast proportion of coronavirus disease 2019 (COVID-19) individuals remain asymptomatic and can shed severe acute respiratory syndrome (SARS-CoV) type 2 virus to transmit the infection, which also explains the exponential increase in the number of COVID-19 cases globally. Furthermore, the rate of recovery from clinical COVID-19 in certain pockets of the globe is surprisingly high. Based on published reports and available literature, here, we speculated a few immunovirological mechanisms as to why a vast majority of individuals remain asymptomatic similar to exotic animal (bats and pangolins) reservoirs that remain refractile to disease development despite carrying a huge load of diverse insidious viral species, and whether such evolutionary advantage would unveil therapeutic strategies against COVID-19 infection in humans. Understanding the unique mechanisms that exotic animal species employ to achieve viral control, as well as inflammatory regulation, appears to hold key clues to the development of therapeutic versatility against COVID-19.

Experimental Modeling of Leprosy in BALB/c, BALB/c Nude, CBA, and C57BL/6ТNF-/- Mice.

Leprosy was modeled in an experiment on BALB/c, BALB/cNude, CBA, and C57BL/6ТNF-/- mice using three Mycobacterium leprae strains obtained from patients with a diagnosis of A30 according to ICD-10 from different regions of the Russian Federation. Proliferation of M. leprae of the used strains showed a temporal-quantitative dependence on the used mouse line. CBA and BALB/cNude mice were optimal for strain R and BALB/c and BALB/cNude lines were optimal for strain I. BALB/cNude mice infected with strain I had low lifespan. M. leprae strain M showed low proliferation activity in BALB/cNude and C57BL/6ТNF-/- mice.

Tumor Necrosis Factor Alpha Deficiency Improves Endothelial Function and Cardiovascular Injury in Deoxycorticosterone Acetate/Salt-Hypertensive Mice.

It has been shown that the inflammatory cytokine tumor necrosis factor α (TNFα) plays a role in the development of hypertension and end-stage renal diseases. We hypothesize that TNFα contributes to endothelial dysfunction and cardiac and vascular injury in deoxycorticosterone acetate (DOCA)/salt-hypertensive mice. The wild-type or TNFα-deficient mice were uninephrectomized and implanted with DOCA pellet treatment for 5 weeks; the mice were given either tap water or 1% NaCl drinking water. DOCA mice developed hypertension (systolic blood pressure (SBP): 167 ± 5 vs. 110 ± 4 mmHg in control group, p < 0.05), cardiac and vascular hypertrophy, and the impairment of endothelium-dependent relaxation to acetylcholine (EDR). TNFα deficiency improved EDR and lowered cardiac and vascular hypertrophy with a mild reduction in SBP (152 ± 4 vs. 167 ± 5 mmHg in DOCA group, p < 0.05) in DOCA mice. The mRNA expressions of the inflammatory cytokines, including TNFα, interleukin 1ß (IL1ß), monocyte chemotactic protein 1 (MCP1), and monocyte/macrophage marker F4/80 were significantly increased in the aorta of DOCA-hypertensive mice; TNFα deficiency reduced these inflammatory gene expressions. DOCA-hypertensive mice also exhibited an increase in the vascular oxidative fluorescence intensities, the protein expressions of gp91phox and p22phox, and the fibrotic factors transforming growth factor ß and fibronectin. TNFα deficiency reduced oxidative stress and fibrotic protein expressions. The DOCA mice also showed a decrease in the protein expression of eNOS associated with increased miR155 expression; TNFα deficiency prevented a decrease in eNOS expression and an increase in miR155 expression in DOCA mice. These results support the idea that TNFα significantly contributes to vascular inflammation, vascular dysfunction, and injury in hypertension.

TNFR2 knockdown triggers apoptosis-induced proliferation in primarily cultured Schwann cells.

After sciatic nerve injury, Schwann cells in the distal segments of injury site undergo apoptosis and meanwhile proliferation. Although apoptosis-induced proliferation (AiP) has been characterized in various models, whether the proliferation of Schwann cells in the distal segments is triggered by apoptosis remains unelucidated. In this study, we used small interfering RNA to knock down the expression of TNFR1 and TNFR2 in primarily cultured Schwann cells, respectively and observed its effects on apoptosis and proliferation. The downregulation of TNFR1 or TNFR2 resulted in a remarkable decrease of cell viability and dramatically increased the apoptosis of Schwann cells. In contrast, the cell apoptosis induced by the knockdown of TNFR2, but not TNFR1, promoted the Schwann cell proliferation. Together, these observations indicated that Schwann cells can undergo AiP, and TNFR2 knockdown triggers the process. Additionally, we established the sciatic nerve injury model on TNF-α knock-out (KO) mice, and found that the Schwann cells of KO mice occurred significantly less apoptosis and proliferation than that of wild-type mice in the distal segments, which indicated TNF-α and its receptors were essential in the massive apoptosis and the apoptosis-induced proliferation of Schwann cells after sciatic nerve injury. The finding of AiP in Schwann cells may be beneficial to develop new approaches to promote axon regeneration and thereby improve the functional recovery after peripheral nerve injury.

Chronic Alcohol Consumption Enhances Skeletal Muscle Wasting in Mice Bearing Cachectic Cancers: The Role of TNFα/Myostatin Axis.

BACKGROUND: Chronic alcohol consumption enhances cancer-associated cachexia, which is one of the major causes of decreased survival. The precise molecular mechanism of how alcohol consumption enhances cancer-associated cachexia, especially skeletal muscle loss, remains to be elucidated. METHODS: We used a mouse model of chronic alcohol consumption, in which 20% (w/v) alcohol was provided as sole drinking fluid, and Lewis lung carcinoma to study the underlying mechanisms. RESULTS: We found that alcohol consumption up-regulated the expression of MAFbx, MuRF-1, and LC3 in skeletal muscle, suggesting that alcohol enhanced ubiquitin-mediated proteolysis and LC3-mediated autophagy. Alcohol consumption enhanced phosphorylation of Smad2/3, p38, and ERK and decreased the phosphorylation of FOXO1. These are the signaling molecules governing protein degradation pathways. Moreover, alcohol consumption slightly up-regulated the expression of insulin receptor substrate-1, did not affect phosphatidylinositol-3 kinase, but decreased the phosphorylation of Akt and mammalian target of rapamycin (mTOR), and down-regulated the expression of Raptor and p70 ribosomal kinase S6 kinase, suggesting that alcohol impaired protein synthesis signaling pathway in skeletal muscle of tumor-bearing mice. Alcohol consumption enhanced the expression of myostatin in skeletal muscle, plasma, and tumor, but did not affect the expression of myostatin in non-tumor-bearing mice. In TNFα knockout mice, the effects of alcohol-enhanced expression of myostatin and protein degradation-related signaling molecules, and decreased protein synthesis signaling in skeletal muscle were abolished. Consequently, alcohol consumption neither affected cancer-associated cachexia nor decreased the survival of TNFα KO mice bearing cachectic cancer. CONCLUSIONS: Chronic alcohol consumption enhances cancer-associated skeletal muscle loss through suppressing Akt/mTOR-mediated protein synthesis pathway and enhancing protein degradation pathways. This process is initiated by TNFα and mediated by myostatin.

TNF deficiency causes alterations in the spatial organization of neurogenic zones and alters the number of microglia and neurons in the cerebral cortex.

BACKGROUND: Although tumor necrosis factor (TNF) inhibitors are used to treat chronic inflammatory diseases, there is little information about how long-term inhibition of TNF affects the homeostatic functions that TNF maintains in the intact CNS. MATERIALS AND METHODS: To assess whether developmental TNF deficiency causes alterations in the naïve CNS, we estimated the number of proliferating cells, microglia, and neurons in the developing neocortex of E13.5, P7 and adult TNF knock out (TNF-/-) mice and wildtype (WT) littermates. We also measured changes in gene and protein expression and monoamine levels in adult WT and TNF-/- mice. To evaluate long-term effects of TNF inhibitors, we treated healthy adult C57BL/6 mice with either saline, the selective soluble TNF inhibitor XPro1595, or the nonselective TNF inhibitor etanercept. We estimated changes in cell number and protein expression after two months of treatment. We assessed the effects of TNF deficiency on cognition by testing adult WT and TNF-/- mice and mice treated with saline, XPro1595, or etanercept with specific behavioral tasks. RESULTS: TNF deficiency decreased the number of proliferating cells and microglia and increased the number of neurons. At the same time, TNF deficiency decreased the expression of WNT signaling-related proteins, specifically Collagen Triple Helix Repeat Containing 1 (CTHRC1) and Frizzled receptor 6 (FZD6). In contrast to XPro1595, long-term inhibition of TNF with etanercept in adult C57BL/6 mice decreased the number of BrdU+ cells in the granule cell layer of the dentate gyrus. Etanercept, but not XPro1595, also impaired spatial learning and memory in the Barnes maze memory test. CONCLUSION: TNF deficiency impacts the organization of neurogenic zones and alters the cell composition in brain. Long-term inhibition of TNF with the nonselective TNF inhibitor etanercept, but not the soluble TNF inhibitor XPro1595, decreases neurogenesis in the adult mouse hippocampus and impairs learning and memory after two months of treatment.

Effect of Differently Polarized Macrophages on Proliferation and Differentiation of Ependymal Cells from Adult Spinal Cord.

Ependymal cells (EpCs) are a kind of multi-potent stem cells in the central canal of adult spinal cord, which proliferate following spinal cord injury (SCI). Although they can differentiate into functional neurons in vitro, EpC progeny differentiate mainly into astrocytes after SCI, and the mechanism remains unclear. The present study aimed to explore whether neuroinflammation induced by classically activated macrophages (M1) or alternatively activated macrophages (M2) had an effect on EpC proliferation and/or differentiation. EpCs were isolated from intact spinal cord of adult mice and co-cultured with M1 or M2, respectively, in vitro. EpC proliferation was detected using a Cell Counting Kit-8 (CCK8) assay and Ki67 staining. Expression of Sox2 (SRY-box 2) in EpCs derived from different groups was detected by immunofluorescence and western blotting. Also explored was whether the mitogen activated protein kinase (MAPK) signaling pathway was involved in EpC proliferation. Immunofluorescence staining of ßIII-tubulin and MAP2 were performed to assess the differentiation direction of EpCs in different culture conditions. Immunofluorescence and western blotting assays showed much more Sox2-positive EpCs in the group EpCs-M1 than the group EpCs-M2 in vitro (p < 0.01). The percentage of EpCs with positive Sox2 staining was decreased after tumor necrosis factor α (TNFα) antibody was added into the medium of EpCs-M1. Correspondingly, fewer Sox2-positive staining cells were observed in the central canal of TNFα-deficient mice with SCI. M1 co-culture promoted EpC proliferation significantly, which could be downregulated by Sox2 gene silencing (p < 0.01). Interestingly, M1 regulated the expression of Sox2 through the MAPK signaling pathway, especially the activation of ERK and p38 kinase. Co-culture in M2 conditioned medium obviously increased the proportion of ßIII-tubulin-positive cells (p < 0.01). Small amounts of MAP2-positive neurons could be detected on day 7 in the M2 group and the control group. M1 conditioned medium could promote EpC proliferation in response to SCI through the TNFα-MAPK-Sox2 signaling pathway; M2 conditioned medium favors EpCs differentiating toward neurons.

TNF May Negatively Regulate Phagocytosis of Devil Facial Tumour Disease Cells by Activated Macrophages.

Introduction: Macrophage phagocytosis of pathogens and tumour cells is an important early event in protection against infectious disease and cancer. As tumour necrosis factor α (TNF) is an important cytokine in macrophage activation, we investigated the involvement of TNF in macrophage phagocytosis of tumour cells. Methods: We used Devil Facial Tumour Disease (DFTD) cancer cells as the target tumour cells. The Tasmanian devil (Sarcophilus harrisii) population is threatened by the transmissible DFTD. Using DFTD cells provided the opportunity to determine if these cells can be phagocytosed and investigate requirement for TNF. As effector cells, bone marrow derived macrophages (BMDMs), generated from C57BL/6 wild type (B6.WT) and C57BL/6 TNF-/- (B6.TNF-/-) mice were used. Phagocytosis of DFTD cells was investigated by confocal microscopy and flow cytometry. Results: DFTD cells were consistently phagocytosed by B6.WT and B6.TNF-/- BMDMs with similar efficiency in vitro. Consequently the DFTD cells are not resistant to phagocytosis. Following activation by exposure to IFNγ and LPS or LPS alone, B6.TNF-/- BMDMs had higher phagocytic efficiency and lower nitric oxide (NO) production compared to wild-type controls. In addition, NO seems to be unlikely to be the involved in phagocytosis efficiency in IFNγ and LPS activated B6.TNF-/- macrophages and consequences thereof. Conclusion: Our results indicate that TNF is not required for IFNγ and LPS or LPS alone activation of macrophage phagocytosis. TNF may negatively regulate macrophage phagocytosis of tumour cells.

Cellular metabolism constrains innate immune responses in early human ontogeny.

Pathogen immune responses are profoundly attenuated in fetuses and premature infants, yet the mechanisms underlying this developmental immaturity remain unclear. Here we show transcriptomic, metabolic and polysome profiling and find that monocytes isolated from infants born early in gestation display perturbations in PPAR-γ-regulated metabolic pathways, limited glycolytic capacity and reduced ribosomal activity. These metabolic changes are linked to a lack of translation of most cytokines and of MALT1 signalosome genes essential to respond to the neonatal pathogen Candida. In contrast, they have little impact on house-keeping phagocytosis functions. Transcriptome analyses further indicate a role for mTOR and its putative negative regulator DNA Damage Inducible Transcript 4-Like in regulating these metabolic constraints. Our results provide a molecular basis for the broad susceptibility to multiple pathogens in these infants, and suggest that the fetal immune system is metabolically programmed to avoid energetically costly, dispensable and potentially harmful immune responses during ontogeny.

Inflammation leads to distinct populations of extracellular vesicles from microglia.

BACKGROUND: Activated microglia play an essential role in inflammatory responses elicited in the central nervous system (CNS). Microglia-derived extracellular vesicles (EVs) are suggested to be involved in propagation of inflammatory signals and in the modulation of cell-to-cell communication. However, there is a lack of knowledge on the regulation of EVs and how this in turn facilitates the communication between cells in the brain. Here, we characterized microglial EVs under inflammatory conditions and investigated the effects of inflammation on the EV size, quantity, and protein content. METHODS: We have utilized western blot, nanoparticle tracking analysis (NTA), and mass spectrometry to characterize EVs and examine the alterations of secreted EVs from a microglial cell line (BV2) following lipopolysaccharide (LPS) and tumor necrosis factor (TNF) inhibitor (etanercept) treatments, or either alone. The inflammatory responses were measured with multiplex cytokine ELISA and western blot. We also subjected TNF knockout mice to experimental stroke (permanent middle cerebral artery occlusion) and validated the effect of TNF inhibition on EV release. RESULTS: Our analysis of EVs originating from activated BV2 microglia revealed a significant increase in the intravesicular levels of TNF and interleukin (IL)-6. We also observed that the number of EVs released was reduced both in vitro and in vivo when inflammation was inhibited via the TNF pathway. Finally, via mass spectrometry, we identified 49 unique proteins in EVs released from LPS-activated microglia compared to control EVs (58 proteins in EVs released from LPS-activated microglia and 37 from control EVs). According to Gene Ontology (GO) analysis, we found a large increase of proteins related to translation and transcription in EVs from LPS. Importantly, we showed a distinct profile of proteins found in EVs released from LPS treated cells compared to control. CONCLUSIONS: We demonstrate altered EV production in BV2 microglial cells and altered cytokine levels and protein composition carried by EVs in response to LPS challenge. Our findings provide new insights into the potential roles of EVs that could be related to the pathogenesis in neuroinflammatory diseases.

Ovariectomy-induced bone loss in TNFα and IL6 gene knockout mice is regulated by different mechanisms.

We examined the effects of tumor necrosis factor-α (TNFα) and interleukin-6 (IL6) gene knockout in preserving the bone loss induced by ovariectomy (OVX) and the mechanisms involved in bone metabolism. Twenty female wild-type (WT), TNFα-knockout (TNFα-/-) or IL6-knockout (IL6-/-) mice aged 12 weeks were sham-operated (SHAM) or subjected to OVX and killed after 4 weeks. Bone mass and skeletal microarchitecture were determined using micro-CT. Bone marrow stromal cells (BMSCs) from all three groups (WT, TNFα-/- and IL6-/-) were induced to differentiate into osteoblasts or osteoclasts and treated with 17-ß-estradiol. Bone metabolism was assessed by histological analysis, serum analyses and qRT-PCR. OVX successfully induced a high turnover in all mice, but a repair effect was observed in TNFα-/- and IL6-/- mice. The ratio of femoral trabecular bone volume to tissue volume, trabecular number and trabecular thickness were significantly decreased in WT mice subjected to OVX, but increased in TNFα-/- mice (1.62, 1.34, 0.27-fold respectively; P < 0.01) and IL6-/- mice (1.34, 0.80, 0.22-fold respectively; P < 0.01). Furthermore, we observed a 29.6% increase in the trabecular number in TNFα-/- mice when compared to the IL6-/- mice. Both, TNFα-/- and IL6-/- BMSCs exhibited decreased numbers of TRAP-positive cells and an increase in ALP-positive cells, with or without E2 treatment (P < 0.05). While the knockout of TNFα or IL6 significantly upregulated mRNA expressions of osteoblast-related genes (Runx2 and Col1a1) and downregulated osteoclast-related mRNA for TRAP, MMP9 and CTSK in vivo and in vitro, TNFα knockout appeared to have roles beyond IL6 knockout in upregulating Col1a1 mRNA expression and downregulating mRNA expressions of WNT-related genes (DKK1 and Sost) and TNF-related activation-induced genes (TRAF6). TNFα seemed to be more potentially invasive in inhibiting bone formation and enhancing TRAF6-mediated osteoclastogenesis than IL6, implying that the regulatory mechanisms of TNFα and IL6 in bone metabolism may be different.

Pivotal Role of TNF-α in the Development and Progression of Nonalcoholic Fatty Liver Disease in a Murine Model.

Previously, we have shown that the adipocyte-specific nuclear form of sterol regulatory element-binding protein-1c (nSREBP-1c) transgenic mice spontaneously developed hepatic lesions that are similar to those of human nonalcoholic steatohepatitis (NASH) with a concomitant elevation of plasma TNF-α. In this study, we analyzed the role of TNF-α in the progression of nonalcoholic fatty liver disease (NAFLD). We established a Tnf knockout nSREBP-1c transgenic mouse line. Glucose tolerance and liver histology were examined at the age of 20 weeks. The gene expression and protein levels were assessed by quantitative RT-PCR and Western blot, respectively. The Tnf knockout improved glucose tolerance and significantly reduced the prevalence of hepatic steatosis (20% vs. 100%, p<0.0001) and fibrosis (15% vs. 65%, p=0.0057). The expressions of Acaca, Scd1, Mcp1, Tgfb1, Col1a1, and Timp1 were increased in the liver from the original nSREBP-1c transgenic mice. However, gene upregulation was reduced in the livers from the Tnf(-/-) nSREBP-1c transgenic mice. Furthermore, the hepatic levels of TIMP1 protein were increased in the original nSREBP-1c transgenic mice but not in Tnf(-/-) nSREBP-1c transgenic mice. To assess the direct effect of TNF-α on the expression of the genes, we cultured primary hepatocytes in the presence of TNF-α and found that TNF-α increased the expression of Mcp1, Tgfb1, and Timp1 in hepatocytes. These observations indicate that TNF-α plays a pivotal role in the development of NAFLD and progression to NASH through upregulating key molecules associated with lipid metabolism, inflammatory cytokines, and fibrosis in the liver.

IL-1ß (Interleukin-1ß) and TNF-α (Tumor Necrosis Factor-α) Impact Abdominal Aortic Aneurysm Formation by Differential Effects on Macrophage Polarization.

OBJECTIVE: Abdominal aortic aneurysms are inflammatory in nature and are associated with some risk factors that also lead to atherosclerotic occlusive disease, most notably smoking. The purpose of our study was to identify differential cytokine expression in patients with abdominal aortic aneurysm and those with atherosclerotic occlusive disease. Based on this analysis, we further explored and compared the mechanism of action of IL (interleukin)-1ß versus TNF-α (tumor necrosis factor-α) in abdominal aortic aneurysm formation. APPROACH AND RESULTS: IL-1ß was differentially expressed in human plasma with lower levels detected in patients with abdominal aortic aneurysm compared with matched atherosclerotic controls. We further explored its mechanism of action using a murine model and cell culture. Genetic deletion of IL-1ß and IL-1R did not inhibit aneurysm formation or decrease MMP (matrix metalloproteinase) expression. The effects of IL-1ß deletion on M1 macrophage polarization were compared with another proinflammatory cytokine, TNF-α. Bone marrow-derived macrophages from IL-1ß-/- and TNF-α-/- mice were polarized to an M1 phenotype. TNF-α deletion, but not IL-1ß deletion, inhibited M1 macrophage polarization. Infusion of M1 polarized TNF-α-/- macrophages inhibited aortic diameter growth; no inhibitory effect was seen in mice infused with M1 polarized IL-1ß-/- macrophages. CONCLUSIONS: Although IL-1ß is a proinflammatory cytokine, its effects on aneurysm formation and macrophage polarization differ from TNF-α. The differential effects of IL-1ß and TNF-α inhibition are related to M1/M2 macrophage polarization and this may account for the differences in clinical efficacy of IL-1ß and TNF-α antibody therapies in management of inflammatory diseases.

Maternal Brain TNF-α Programs Innate Fear in the Offspring.

Tumor necrosis factor alpha (TNF-α) is a cytokine that not only coordinates local and systemic immune responses [1, 2] but also regulates neuronal functions. Most prominently, glia-derived TNF-α has been shown to regulate homeostatic synaptic scaling [3-6], but TNF-α-null mice exhibited no apparent cognitive or emotional abnormalities. Instead, we found a TNF-α-dependent intergenerational effect, as mothers with a deficit in TNF-α programmed their offspring to exhibit low innate fear. Cross-fostering and conditional knockout experiments indicated that a TNF-α deficit in the maternal brain, rather than in the hematopoietic system, and during gestation was responsible for the low-fear offspring phenotype. The level of innate fear governs the balance between exploration/foraging and avoidance of predators and is thus fundamentally important in adaptation, fitness, and survival [7]. Because maternal exercise and activity are known to reduce both brain TNF-α [8] and offspring innate fear [9], whereas maternal stress has been reported to increase brain TNF-α [10] and offspring fear and anxiety [11, 12], maternal brain TNF-α may report environmental conditions to promote offspring behavioral adaptation to their anticipated postnatal environment.

Inactivation of TNF/LT locus alters mouse metabolic response to concentrated ambient PM2.5.

BACKGROUND: Exposure to ambient fine particulate matter (PM2.5) is associated with increased cardiometabolic morbidity and mortality. This is widely believed to be attributable to PM2.5 exposure-induced pulmonary and subsequent systemic inflammation. Tumor necrosis factor alpha (TNFα), lymphotoxin α (LTα), and lymphotoxin ß (LTß) are three homologous pro-inflammatory cytokines, each with both unique and redundant activities in inflammation. Their role in PM2.5 exposure-induced inflammation and adverse cardiometabolic effects has to be determined. METHODS AND RESULTS: LTα/TNFα/LTß triple-knockout (TNF/LT KO) and wildtype (WT) mice were exposed to concentrated ambient PM2.5 (CAP) for 5 months. Lung pathological analysis revealed that TNF/LT deficiency reduced CAP exposure-induced pulmonary inflammation. However, glucose homeostasis assessments showed that TNF/LT deficiency significantly aggravated CAP exposure-induced glucose intolerance and insulin resistance. Consistent with glucose homeostasis assessments, CAP exposure significantly increased the body weight and adiposity of TNF/LT KO but not WT mice. In contrast to its body weight effects, CAP exposure reduced food intake of WT but not TNF/LT KO mice. On the other hand, CAP exposure induced marked fat droplet accumulation in brown adipose tissues of WT mice and significantly decreased their uncoupling protein 1 (UCP1) expression, and these effects were markedly exacerbated in TNF/LT KO mice. CONCLUSION: The present study suggests that TNF/LT deficiency influences PM2.5 exposure-induced response of energy metabolism through alterations in both food intake and energy expenditure.

TNFα deficiency results in increased IL-1ß in an early onset of spontaneous murine colitis.

Inflammatory bowel disease (Crohn's disease (CD) and ulcerative colitis (UC)) is a multifactorial disease resulting from immune dysregulation in the gut. The underlying colitis is characterized by high levels of inflammatory cytokines, including TNFα. Biological intervention for IBD patients using anti-TNFα antibodies is often an effective therapeutic solution. However, TNFα neutralization fails to induce remission in a subgroup of IBD patients, primarily in UC patients. There is a dearth of suitable animal models representing TNFα non-responders. Here we have combined one of the best UC models currently available, namely Winnie and the TNFαKO mouse to generate a TNFα-deficient Winnie to study early onset colitis. The induced TNFα deficiency with underlying colitis does not influence general health (viability and body weight) or clinical parameters (colon weight, colon length and histological colitis) when compared with the Winnie genotype alone. The molecular characterization resulted in identification of Il1ß as the major elevated cytokine during early phases of colitis. Further, in vitro functional assay using bone marrow-derived dendritic cells confirmed IL-1ß as the major cytokine released in the absence of TNFα. This study has generated a successful model of colitis that remains TNFα non-responsive and has demonstrated that IL-1ß expression is a major pathway for the progression of colitis in this system. These data also suggest that IL-1ß can be a potential target for clinical intervention of UC patients who fail to respond to TNFα neutralization.

TNFα induced up-regulation of Na+,K+,2Cl- cotransporter NKCC1 in hepatic ammonia clearance and cerebral ammonia toxicity.

The devastating consequences of hepatic failure include hepatic encephalopathy, a severe, life threatening impairment of neuronal function. Hepatic encephalopathy is caused by impaired hepatic clearance of NH4+. Cellular NH4+ uptake is accomplished mainly by the Na+,K+,2Cl- cotransporter. Here we show that hepatic clearance of NH4+ is impaired in TNFα deficient as well as TNFR1&TNFR2 double knockout mice, which both develop hyperammonemia. Despite impaired hepatic clearance of NH4+, TNFα deficient mice and TNFR1 deficient mice were protected against acute ammonia intoxication. While 54% of the wild-type mice and 60% of TNFR2 deficient mice survived an NH4+ load, virtually all TNFα deficient mice and TNFR1 deficient mice survived the treatment. Conversely, TNFα treatment of wild type mice sensitized the animals to the toxic effects of an NH4+ load. The protection of TNFα-deficient mice against an NH4+ load was paralleled by decreased cerebral expression of NKCC1. According to the present observations, inhibition of TNFα formation and/or NKCC1 may be strategies to favorably influence the clinical course of hepatic encephalopathy.