TNF-α Transgenic Mice Research Articles

Galectin-8 involves in arthritic condylar bone loss via podoplanin/AKT/ERK axis-mediated inflammatory lymphangiogenesis

The lymphatic system plays a crucial role in the maintenance of tissue fluid homeostasis and the immunological response to inflammation. Galectin-8 (Gal-8) regulates pathological lymphangiogenesis but the effects of which on inflammation-related condylar bone loss in temporomandibular joint (TMJ) have not been well studied. We used TNFα-transgenic (TNFTG) mice and their wildtype (WT) littermates to compare their inflammatory phenotype in TMJs. Next, lymphatic endothelial cells (LECs) were used to examine the effects of which on osteoclast formation, pro-inflammatory factor expression, and inflammatory lymphangiogenesis with or without thiodigalactoside (TDG, a Gal-8 inhibitor) treatment. At last, two murine models (TNFTG arthritic model and forced mouth opening model) were used to explore TDG as a potential drug for the treatment of inflammation-related condylar bone loss. In comparison to WT mice, lymphatic areas of lymphatic vessel endothelial receptor 1 (LYVE1)+/podoplanin (PDPN)+ and Gal-8+/PDPN+, TRAP-positive osteoclast number, and condylar bone loss are increased in TNFTG mice. Inhibition of Gal-8 in LECs by TDG, reduces TNFα-induced osteoclast formation, pro-inflammatory factor expression, and inflammatory lymphangiogenesis. In addition, Gal-8 promotes TNFα-activated AKT/ERK/NF-κB pathways by binding to PDPN. Finally, the administration of TDG attenuates inflammatory lymphangiogenesis, inhibits osteoclast activity, and reduces condylar bone loss in TNFTG arthritic mice and forced mouth opening mice. Our findings reveal the important role of Gal-8-promoted pathological lymphangiogenesis in inflammation-related condylar bone loss.

Gut commensal Parabacteroides distasonis alleviates inflammatory arthritis

ObjectiveGut microbiota dysbiosis is closely linked to the pathogenesis of rheumatoid arthritis (RA). We aimed to identify potential probiotic gut microbes that can ameliorate the development of RA.DesignMicrobiota profiling in...

Teriparatide prevented synovial inflammation and cartilage destruction in mice with DMM

ABSTRACT Aim Emerging data have demonstrated that low-grade inflammation in osteoarthritis, a long-held degenerative disease. The inflamed synovium produces various cytokines that induce cartilage destruction and joint pain. A previous study showed that teriparatide, an FDA approved anti-osteoporotic drug, may enhance cartilage repair. Our study focuses on its role in OA synovitis. Materials and Methods Primary mouse articular chondrocytes were used to determine the most potent cytokines involved in OA inflammation and cartilage destruction. A destabilization of the medial meniscus mouse model was established to investigate the effect of teriparatide in OA, particularly, on synovial inflammation and cartilage degradation. Results In vitro experiments showed that TNF-α was the most potent inducer of cartilage matrix-degrading enzymes, and that teriparatide antagonized the TNF-α of effect. Consistently, articular cartilage samples from TNF-α transgenic mice contained more MMP-13 positive chondrocytes than those from wild type mice. In addition, more type II collagen was cleaved in human OA cartilage than in normal cartilage samples. Conclusions Teriparatide can prevent synovitis and cartilage degradation by suppressing TNF-α mediated MMP-13 overexpression. Together with its chondroregenerative capability, teriparatide may be the first effective disease modifying osteoarthritis drug.

Maackia amurensis seed lectin (MASL) ameliorates articular cartilage destruction and increases movement velocity of mice with TNFα induced rheumatoid arthritis

Up to 70 million people around the world suffer from rheumatoid arthritis. Current treatment options have varied efficacy and can cause unwanted side effects. New approaches are needed to treat this condition. Sialic acid modifications on chondrocyte receptors have been associated with arthritic inflammation and joint destruction. For example, the transmembrane mucin receptor protein podoplanin (PDPN) has been identified as a functionally relevant receptor that presents extracellular sialic acid motifs. PDPN signaling promotes inflammation and invasion associated with arthritis and, therefore, has emerged as a target that can be used to inhibit arthritic inflammation. Maackia amurensis seed lectin (MASL) can target PDPN on chondrocytes to decrease inflammatory signaling cascades and reduce cartilage destruction in a lipopolysaccharide induced osteoarthritis mouse model. Here, we investigated the effects of MASL on rheumatoid arthritis progression in a TNFα transgenic (TNF-Tg) mouse model. Results from this study indicate that MASL can be administered orally to ameliorate joint malformation and increase velocity of movement exhibited by these TNF-Tg mice. These data support the consideration of MASL as a potential treatment for rheumatoid arthritis.

TRAPS mutations in Tnfrsf1a decrease the responsiveness to TNFα via reduced cell surface expression of TNFR1.

Tumor necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS) is an autoinflammatory periodic fever syndrome associated with heterozygous mutations in TNFRSF1A, which encodes TNF receptor type I (TNFR1). Although possible proinflammatory mechanisms have been proposed, most previous studies were performed using in vitro overexpression models, which could lead to undesirable inflammatory responses due to artificial overexpression. It is crucial to reproduce heterozygous mutations at physiological expression levels; however, such studies remain limited. In this study, we generated TRAPS mutant mice and analyzed their phenotypes. Three Tnfrsf1a mutant strains were generated by introducing T79M, G87V, or T90I mutation. T79M is a known mutation responsible for TRAPS, whereas G87V is a TRAPS mutation that we have reported, and T90I is a variant of unknown significance. Using these murine models, we investigated whether TRAPS mutations could affect the inflammatory responses in vivo and in vitro. We found that none of the mutant mice exhibited detectable inflammatory phenotypes under standard housing conditions for 1 year. Interestingly, TRAPS mutant (T79M and G87V) mice had reduced mortality rates after the administration of lipopolysaccharide (LPS) and D-galactosamine, which induce TNFα-dependent lethal hepatitis. Moreover, TRAPS mutations strongly suppressed the development of TNFα-mediated arthritis when crossed with human TNFα transgenic mice. In in vitro primary bone marrow-derived macrophage cultures, the T79M and G87V mutations attenuated the inflammatory responses to TNFα compared with the wild-type, whereas these mutations did not alter the responsiveness of these cells to LPS. The T90I mutant macrophages behaved similarly to wild type in response to LPS and TNFα. The TNFR1 levels were increased in whole-cell lysates of TRAPS mutant macrophages, whereas the cell surface expression of TNFR1 was significantly decreased in TRAPS mutant macrophages. Taken together, TRAPS mutations did not augment the inflammatory responses to TNFα and LPS; instead, they suppressed the response to TNFα via decreased cell surface expression of TNFR1. The stimulation of lymphotoxin-α, adenosine triphosphate, and norepinephrine in primary macrophages or various stimuli in murine splenocytes did not induce detectable inflammatory responses. In conclusion, TRAPS mutations suppressed responsiveness to TNFα, and TRAPS-associated inflammation is likely induced by unconfirmed disease-specific proinflammatory factors.

Tumor necrosis factor-α promotes osteoclast differentiation via sialylation in mice

To explore the mechanism through which tumor necrosis factor-α (TNF-α) promotes osteoclast differentiation. Bilateral knee joint samples were collected from 4-month-old wild-type mice and TNF-α transgenic mice for CT scan analysis, TRAP staining and sialic acid staining analysis. The osteoclast precursor (RAW264.7) cells were cultured for 3 days in induction medium in the presence of vehicle, TNF-α, or TNF-α and sialidase, and were then examined with RT-qPCR, TRAP staining, and sialic acid immunofluorescence co-localization staining. Bone marrow-derived macrophages isolated from the wild-type mice and TNF-α transgenic mouse and cultured in induction medium with or without the addition of sialidase, and TRAP and sialic acid staining was performed after 3 days of cell culture. TRAP staining showed that the number of osteoclasts increased significantly in TNF-α transgenic mice as compared with the wild-type mice (P < 0.0001), and micro-CT analysis revealed significant reductions of BV/TV, Tb.N, and Tb.Th in TNF-α transgenic mice (P < 0.001). The osteoclasts in TNF-α transgenic mice also showed a significantly increased expression of sialic acid (P=0.004). In the cell experiment, RAW264.7 cells cultured with TNF-α showed a significantly higher expression of sialic acid (P < 0.0001) and a greater osteoclast formation rate (P=0.0007) than the the control cells, while the addition of sialidase significantly reduced sialic acid expression, osteoclast formation rate and TRAP mRNA level in TNF-α-treated cells (P < 0.0001). Similarly, in the bone marrow-derived macrophages, sialic acid expression and osteoclast formation rate were significantly increased by incubation with TNF-α (P < 0.0001), but the increments were obviously reduced by addition of sialidase in the medium (P < 0.0001). TNF-α can promote the differentiation and activity of osteoclasts by increasing the sialylation level in the osteoclasts.

TNFα induces endothelial dysfunction in rheumatoid arthritis via LOX-1 and arginase 2: reversal by monoclonal TNFα antibodies.

Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting joints and blood vessels. Despite low levels of low-density lipoprotein cholesterol (LDL-C), RA patients exhibit endothelial dysfunction and are at increased risk of death from cardiovascular complications, but the molecular mechanism of action is unknown. We aimed in the present study to identify the molecular mechanism of endothelial dysfunction in a mouse model of RA and in patients with RA. Endothelium-dependent relaxations to acetylcholine were reduced in aortae of two tumour necrosis factor alpha (TNFα) transgenic mouse lines with either mild (Tg3647) or severe (Tg197) forms of RA in a time- and severity-dependent fashion as assessed by organ chamber myograph. In Tg197, TNFα plasma levels were associated with severe endothelial dysfunction. LOX-1 receptor was markedly up-regulated leading to increased vascular oxLDL uptake and NFκB-mediated enhanced Arg2 expression via direct binding to its promoter resulting in reduced NO bioavailability and vascular cGMP levels as shown by ELISA and chromatin immunoprecipitation. Anti-TNFα treatment with infliximab normalized endothelial function together with LOX-1 and Arg2 serum levels in mice. In RA patients, soluble LOX-1 serum levels were also markedly increased and closely related to serum levels of C-reactive protein. Similarly, ARG2 serum levels were increased. Similarly, anti-TNFα treatment restored LOX-1 and ARG2 serum levels in RA patients. Increased TNFα levels not only contribute to RA, but also to endothelial dysfunction by increasing vascular oxLDL content and activation of the LOX-1/NFκB/Arg2 pathway leading to reduced NO bioavailability and decreased cGMP levels. Anti-TNFα treatment improved both articular symptoms and endothelial function by reducing LOX-1, vascular oxLDL, and Arg2 levels.

BAD inactivation exacerbates rheumatoid arthritis pathology by promoting survival of sublining macrophages.

The resistance of synovial sublining macrophages to apoptosis has a crucial role in joint inflammation and destruction in rheumatoid arthritis (RA). However, the underlying mechanism is incompletely understood. Here we report that inactivation of the pro-apoptotic BCL-2 family protein BAD is essential for survival of synovial sublining macrophage in RA. Genetic disruption of Bad leads to more severe joint inflammation and cartilage and bone damage with reduced apoptosis of synovial sublining macrophages in collagen-induced arthritis (CIA) and TNFα transgenic (TNF-Tg) mouse models. Conversely, Bad3SA/3SA mice, in which BAD can no longer be inactivated by phosphorylation, are protected from collagen-induced arthritis. Mechanistically, phosphorylation-mediated inactivation of BAD specifically protects synovial sublining macrophages from apoptosis in highly inflammatory environment of arthritic joints in CIA and TNF-Tg mice, and in patients with RA, thereby contributing to RA pathology. Our findings put forward a model in which inactivation of BAD confers the apoptosis resistance on synovial sublining macrophages, thereby contributing to the development of arthritis, suggesting that BAD may be a potential therapeutic target for RA.

Increased SUMO-activating enzyme SAE1/UBA2 promotes glycolysis and pathogenic behavior of rheumatoid fibroblast-like synoviocytes.

Fibroblast-like synoviocytes (FLSs) are critical to joint inflammation and destruction in rheumatoid arthritis (RA). Increased glycolysis in RA FLSs contributes to persistent joint damage. SUMOylation, a posttranslational modification of proteins, plays an important role in initiation and development of many diseases. However, the role of small ubiquitin-like modifier–activating (SUMO-activating) enzyme 1 (SAE1)/ubiquitin like modifier activating enzyme 2 (UBA2) in regulating the pathogenic FLS behaviors is unknown. Here, we found an increased expression of SAE1 and UBA2 in FLSs and synovial tissues from patients with RA. SAE1 or UBA2 knockdown by siRNA and treatment with GA, an inhibitor of SAE1/UBA2-mediated SUMOylation, resulted in reduced glycolysis, aggressive phenotype, and inflammation. SAE1/UBA2-mediated SUMOylation of pyruvate kinase M2 (PKM2) promoted its phosphorylation and nuclear translocation and decreased PK activity. Moreover, inhibition of PKM2 phosphorylation increased PK activity and suppressed glycolysis, aggressive phenotype, and inflammation. We further demonstrated that STAT5A mediated SUMOylated PKM2-induced glycolysis and biological behaviors. Interestingly, GA treatment attenuated the severity of arthritis in mice with collagen-induced arthritis and human TNF-α transgenic mice. These findings suggest that an increase in synovial SAE1/UBA2 may contribute to synovial glycolysis and joint inflammation in RA and that targeting SAE1/UBA2 may have therapeutic potential in patients with RA.

Concomitant Treatment with Etanercept and Tacrolimus Synergistically Attenuates Arthritis Progression via Inhibition of Matrix Metalloproteinase-3 Production and Osteoclastogenesis in Human TNF-α Transgenic Mice.

In the present study, we investigated the effects and mechanisms of action of a combined treatment with etanercept, a soluble tumor necrosis factor receptor (p75) Fc fusion protein, and tacrolimus, a calcineurin inhibitor on the progression of arthritis in human tumor necrosis factor-α (TNF-α) transgenic (hTNF-Tg) mice. Single-drug treatments with etanercept and tacrolimus attenuated the clinical signs but not the radiographic changes associated with the development of arthritis in mice. On the contrary, combined treatment significantly suppressed the radiographic progression and also improved the clinical signs. The combined treatment exhibited synergistic effects of the two drugs in reducing the serum matrix metalloproteinase-3 level and the number of peripheral CD11bhigh osteoclast precursor cells. Moreover, tacrolimus inhibited the cytokine-induced osteoclast differentiation in synergy with etanercept in an in vitro assay. Interestingly, tacrolimus did not inhibit the production of antidrug antibodies (ADAs) against etanercept in the hTNF-Tg mice. This result implies that the synergistic effects of etanercept and tacrolimus are not due to secondary effects derived from the suppression of ADA production by tacrolimus but are due to their primary effects. These findings suggest that concomitant treatment with etanercept and tacrolimus may be one of preferable treatment options to control disease activities for patients with rheumatoid arthritis, especially for those with bone resorption.

Fexofenadine inhibits TNF signaling through targeting to cytosolic phospholipase A2 and is therapeutic against inflammatory arthritis

ObjectiveTumour necrosis factor alpha (TNF-α) signalling plays a central role in the pathogenesis of various autoimmune diseases, particularly inflammatory arthritis. This study aimed to repurpose clinically approved drugs as potential...

Anti-TNF-α restricts dengue virus-induced neuropathy.

Proinflammatory TNF-α facilitates dengue virus (DENV) infection in endovascular dysfunction and neurotoxicity. The introduction of TNF-α blocking therapy with Abs is performed to test its therapeutic effect in this study. In DENV-infected mice, TNF-α production in the brain accompanied the progression of neurotoxicity and encephalitis. DENV infection caused the loss of hippocampal neurons with TNF-α expression around damaged regions, and immunostaining showed the induction of apoptosis in hippocampal neurons. TNF-α was expressed in active microglia and astrocytes in DENV-infected mice. TNF-α facilitated DENV-induced neurotoxicity in vitro in murine Neuro-2a cells. Using a currently established encephalitic mouse model in which DENV infection causes progressive hunchback posture, limbic seizures, limbic weakness, paralysis, and lethality 7 days postinfection, we showed that TNF-α transgenic mice represented the progressive disease development and administration of neutralizing TNF-α Ab reduced dengue encephalitis and mortality. These results demonstrate an immunopathogenesis of TNF-α for mediating DENV-induced encephalitis-associated neurotoxicity and that targeting TNF-α can be used as a strategy against dengue encephalitis.

Targeting TNF-α against dengue virus-induced neurotoxicity and acute viral encephalitis-like symptoms

Abstract Pro-inflammatory tumor necrosis factor α (TNF-α) facilitates dengue virus (DENV) infection in endovascular dysfunction and neurotoxicity. The introduction of TNF-α blocking therapy with antibodies and antagonists is performed for testing its therapeutic effects in this study. In DENV-infected mice, TNF-α was produced in the brains accompanied by the progression of neurotoxicity and encephalitis. DENV infection caused loss in hippocampal neurons with TNF-α expression around the damaged regions. Additionally, immunostaining showed the induction of apoptosis in hippocampal neurons. TNF-α was expressed in active microglia as well as astrocytes of DENV-infected mice. TNF-α facilitated DENV-induced neurotoxicity in vitro in murine Neuro-2a cells. By using a currently established encephalitic mice model that DENV infection caused progressive hunchback posture, limbic seizures, limbic weakness, paralysis, and lethality 7 days post-infection, TNF-α transgenic mice represented the progressive disease development while administration of neutralizing TNF-α antibody reduced dengue encephalitis and mortality. These results demonstrate an immunopathogenesis of TNF-α for mediating DENV-induced encephalitis-associated neurotoxicity and targeting TNF-α can be used as a strategy against dengue encephalitis.

Impaired periodontium and temporomandibular joints in tumour necrosis factor-α transgenic mice.

Tumour necrosis factor (TNF)-α is a pathological factor causing the characteristic symptoms of periodontal disease and rheumatoid arthritis. In this study, we describe the phenotypes of human TNF-α transgenic mice (hTNFtg) with respect to their periodontium and the temporomandibular joint (TMJ). Periodontal structures, TMJ and skull shape of hTNFtg mice and wild-type (WT) littermates were assessed by microcomputed tomography, automated segmentation, geometric morphometrics and histologic ground sections. We show that hTNFtg mice have an eroded lamina dura and reduced periodontal ligament space compared to (WT) littermates. Transgenic mice further exhibit severe destruction of the TMJ. Geometric morphometrics revealed that hTNFtg mice have a more laterally positioned TMJ with a concomitantly enlarged zygomatic process. Mandibular and maxillary teeth occluded properly. Our findings suggest that chronic inflammation in hTNFtg mice causes destructive changes of the periodontium and the TMJ.

Cerebral Oxidative Stress and Microvasculature Defects in TNF-α Expressing Transgenic and Porphyromonas gingivalis-Infected ApoE-/- Mice.

The polymicrobial dysbiotic subgingival biofilm microbes associated with periodontal disease appear to contribute to developing pathologies in distal body sites, including the brain. This study examined oxidative stress, in the form of increased protein carbonylation and oxidative protein damage, in the tumor necrosis factor-α (TNF-α) transgenic mouse that models inflammatory TNF-α excess during bacterial infection; and in the apolipoprotein knockout (ApoE-/-) mouse brains, following Porphyromonas gingivalis gingival monoinfection. Following 2,4-dinitrophenylhydrazine derivatization, carbonyl groups were detected in frontal lobe brain tissue lysates by immunoblotting and immunohistochemical analysis of fixed tissue sections from the frontotemporal lobe and the hippocampus. Immunoblot analysis confirmed the presence of variable carbonyl content and oxidative protein damage in all lysates, with TNF-α transgenic blots exhibiting increased protein carbonyl content, with consistently prominent bands at 25 kDa (p = 0.0001), 43 kDa, and 68 kDa, over wild-type mice. Compared to sham-infected ApoE-/- mouse blots, P. gingivalis-infected brain tissue blots demonstrated the greatest detectable protein carbonyl content overall, with numerous prominent bands at 25 kDa (p = 0.001) and 43 kDa (p = 0.0001) and an exclusive band to this group between 30-43 kDa* (p = 0.0001). In addition, marked immunostaining was detected exclusively in the microvasculature in P. gingivalis-infected hippocampal tissue sections, compared to sham-infected, wild-type, and TNF-α transgenic mice. This study revealed that the hippocampal microvascular structure of P. gingivalis-infected ApoE-/- mice possesses elevated oxidative stress levels, resulting in the associated tight junction proteins being susceptible to increased oxidative/proteolytic degradation, leading to a loss of functional integrity.

Arthritis models: usefulness and interpretation

Animal models of arthritis are used to better understand pathophysiology of a disease or to seek potential therapeutic targets or strategies. Focusing on models currently used for studying rheumatoid arthritis, we show here in which extent models were invaluable to enlighten different mechanisms such as the role of innate immunity, T and B cells, vessels, or microbiota. Moreover, models were the starting point of in vivo application of cytokine-blocking strategies such as anti-TNF or anti-IL-6 treatments. The most popular models are the different types of collagen-induced arthritis and arthritis in KBN mice. As spontaneous arthritides, human TNF-α transgenic mice are a reliable model. It is mandatory to use animal models in the respect of ethical procedure, particularly regarding the number of animals and the control of pain. Moreover, design of experiments should be of the highest level, animal models of arthritis being dedicated to exploration of well-based novelties, and never used for confirmation or replication of already proven concepts. The best interpretations of data in animal models of arthritis suppose integrated research, including translational studies from animals to humans.

NAMPT Is an Essential Regulator of RA-Mediated Periodontal Inflammation

Recent studies have indicated a potential correlation between rheumatoid arthritis (RA) and periodontal inflammation. We undertook this study to verify whether RA mediates periodontitis-like phenotypes in experimental mouse models of RA and to explore the role of nicotinamide phosphoribosyltransferase (NAMPT) in periodontal inflammation during RA pathogenesis. Periodontal inflammation and alveolar bone loss have been reported in mice with collagen-induced arthritis (CIA) and in genetically modified tumor necrosis factor–α (TNF-α) transgenic (TG) mouse models. Among the adipokines examined in our study, NAMPT expression was markedly upregulated in the periodontal ligament (PDL) tissues in RA mouse models and in human PDL cells stimulated by the proinflammatory cytokines, interleukin (IL) 1β and TNF-α. When NAMPT was overexpressed with the Nampt-synthesizing adenovirus vector (Ad-Nampt), the PDL cells exhibited an increased expression of cytokines (IL6), chemokines (IL8 and chemokine [C-C motif] ligand 5 [CCL5]), inflammatory mediators (cyclooxygenase 2 [COX-2]), and matrix-degrading enzymes (matrix metalloproteinase [MMP] 1 and MMP3). Inhibition of NAMPT by the intracellular NAMPT (iNAMPT) inhibitor, FK866, or by the sirtuin inhibitor, nicotinamide, in PDL cells led to inhibition of the IL1β or Ad-Nampt–induced upregulation of catabolic factors, whereas treatment with recombinant NAMPT protein or blockade of extracellular NAMPT (eNAMPT) with blocking antibody did not. Moreover, NAMPT inhibition by the intraperitoneal or intragingival injection of FK866 in CIA mice inhibited periodontal tissue damage, under conditions of RA. Thus, our results verified the co-occurrence of RA and periodontal inflammation using experimental mouse models of RA, suggesting that iNAMPT in PDL cells plays a pivotal role in the pathogenesis of RA-mediated periodontal inflammation by regulating the expression levels of catabolic genes, such as IL6, IL8, CCL5, COX-2, MMP1, and MMP3.

Improving the efficacy and safety of biologic drugs with tolerogenic nanoparticles.

The development of antidrug antibodies (ADAs) is a common cause for the failure of biotherapeutic treatments and adverse hypersensitivity reactions. Here we demonstrate that poly(lactic-co-glycolic acid) (PLGA) nanoparticles carrying rapamycin, but not free rapamycin, are capable of inducing durable immunological tolerance to co-administered proteins that is characterized by the induction of tolerogenic dendritic cells, an increase in regulatory T cells, a reduction in B cell activation and germinal centre formation, and the inhibition of antigen-specific hypersensitivity reactions. Intravenous co-administration of tolerogenic nanoparticles with pegylated uricase inhibited the formation of ADAs in mice and non-human primates and normalized serum uric acid levels in uricase-deficient mice. Similarly, the subcutaneous co-administration of nanoparticles with adalimumab resulted in the durable inhibition of ADAs, leading to normalized pharmacokinetics of the anti-TNFα antibody and protection against arthritis in TNFα transgenic mice. Adjunct therapy with tolerogenic nanoparticles represents a novel and broadly applicable approach to prevent the formation of ADAs against biologic therapies.

Critical role of tumor necrosis factor receptor 1 in the pathogenesis of pulmonary emphysema in mice.

COPD is a major cause of chronic morbidity and mortality throughout the world. Although tumor necrosis factor-α (TNF-α) has a critical role in the development of COPD, the role of different TNF receptors (TNFRs) in pulmonary emphysema has not been resolved. We aimed to clarify the role of TNFRs in the development of pulmonary emphysema. TNF-α transgenic mice, a murine model of COPD in which the mice spontaneously develop emphysema with a large increase in lung volume and pulmonary hypertension, were crossed with either TNFR1-deficient mice or TNFR2-deficient mice. After 6 months, the gross appearance of the lung, lung histology, and pulmonary and cardiac physiology were determined. In addition, the relationship between apoptosis and emphysema was investigated. Pulmonary emphysema-like changes disappeared with deletion of TNFR1. However, slight improvements were attained with deletion of TNFR2. Apoptotic cells in the interstitium of the lung were observed in TNF-α transgenic mice. The apoptotic signals through TNFR1 appear critical for the pathogenesis of pulmonary emphysema. In contrast, the inflammatory process has a less important role for the development of emphysema.

Copper Deficiency in the Lungs of TNF-α Transgenic Mice.

Tumor necrosis factor (TNF)-α is a well-known pro-inflammatory cytokine. Increased expression of Tnf-α is a feature of inflammatory lung diseases, such as asthma, emphysema, fibrosis, and smoking-induced chronic obstructive pulmonary disease (COPD). Using a mouse line with lung-specific Tnf-α overexpression (SPC-TNF-α) to mimic TNF-α-associated lung diseases, we investigated the role of chronic inflammation in the homeostasis of lung trace elements. We performed a quantitative survey of micronutrients and biometals, including copper (Cu), zinc (Zn), and selenium (Se), in the transgenic mice tissues. We also examined the expression of Cu-dependent proteins in the inflammatory lung tissue to determine whether they were affected by the severe Cu deficiency, including cuproenzymes, Cu transporters, and Cu chaperones. We found consistent lung-specific reduction of the metal Cu, with a mean decrease of 70%; however, Zn and Se were unaffected in all other tissues. RT-PCR showed that two Cu enzymes associated with lung pathology were downregulated: amine oxidase, Cu containing 3 (Aoc3) and lysyl oxidase (Lox). Two factors, vascular endothelial growth factor (Vegf) and focal adhesion kinase (Fak), related with Cu deficiency treatment, showed decreased expression in the transgenic inflammatory lung. We concluded that Cu deficiency occurs following chronic TNF-α-induced lung inflammation and this likely plays an essential role in the inflammation-induced lung damage. These results suggest the restoration of lung Cu status as a potential strategy in both treatment and prevention of chronic lung inflammation and related disorders.