Tumor necrosis factors in 1996

Impaired Periodontitis-Induced Cytokine Production by Peripheral Blood Monocytes and Myeloid Dendritic Cells in Patients with Rheumatoid Arthritis: A Case-Control Study

Background: Immune cells from rheumatoid arthritis (RA) patients display a reduced in vitro response to Porphyromonas gingivalis (P. gingivalis), which may have functional immune consequences. The aim of this study was to characterize, by flow cytometry, the frequency/activity of monocytes and naturally occurring myeloid dendritic cells (mDCs) in peripheral blood samples from patients with periodontitis and patients with periodontitis and RA. Methods: The relative frequency of monocytes and mDCs in the whole blood, the frequency of these cells producing TNFα or IL-6 and the protein expression levels for each cytokine, before and after stimulation with lipopolysaccharide (LPS) from Escherichia coli plus interferon-γ (IFN-γ), were assessed by flow cytometry, in peripheral blood samples from 10 healthy individuals (HEALTHY), 10 patients with periodontitis (PERIO) and 17 patients with periodontitis and RA (PERIO+RA). Results: The frequency of monocytes and mDCs producing IL-6 or TNF-α and the expression of IL-6 and TNF-α in the PERIO group were generally higher. Within the PERIO+RA group, P. gingivalis and related antibodies were negatively correlated with the monocyte and mDC expression of IL-6. A subgroup of the PERIO+RA patients that displayed statistically significantly lower frequencies of monocytes producing IL-6 after activation presented statistically significantly higher peptidylarginine deiminase (PAD)2/4 activity, anti-arg-gingipain (RgpB) IgG levels, mean probing depth (PD), periodontal inflamed surface area (PISA) and bleeding on probing (BoP). Conclusions: In the patients with PERIO+RA, innate immune cells seemed to produce lower amounts of pro-inflammatory cytokines, which are correlated with worse periodontitis-related clinical and microbiological parameters.

Host Responses in the Link Between Periodontitis and Rheumatoid Arthritis

Periodontitis and rheumatoid arthritis (RA) are common chronic inflammatory conditions and share many clinical and pathologic features. There is evidence to suggest that similar profiles of cytokine genotypes and their coding proteins are involved in the pathogenesis of periodontitis and RA. In particular, constitutive overproduction of pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), has been implicated to play a pathologic role in the two inflammatory diseases. Results from studies with animal and human subjects have suggested an improvement of periodontal inflammatory condition after treatment with TNF-α inhibitors. Likewise, IL-6 receptor inhibition therapy has been suggested to have an effect on control of periodontal inflammation in patients with RA. In the present review, we provide an overview of studies showing the pathological role of cytokines in the linkage between periodontitis and RA, and further summarize the current studies assessing the effect of cytokine targeted therapy on periodontal condition.

The role of osteoimmunology in periodontal disease

Periodontal disease is a pathological condition that involves inflammation of the tooth supporting structures. It occurs in response to the presence of bacterial plaque on the tooth structure. The host defense system, including innate and adaptive immunity, is responsible for combating the pathologic bacteria invading the periodontal tissue. Failure to eradicate the invading pathogens will result in a continuous state of inflammation where inflammatory cells such as lymphocytes, PMNs, and macrophages will continue to produce inflammatory mediators in an effort to destroy the invaders. Unfortunately, these inflammatory mediators have a deleterious effect on the host tissue as well as foreign microbes. One of the effects of these mediators on the host is the induction of matrix degradation and bone resorption through activation of proteases and other inflammatory mediators that activate osteoclasts.

Emerging role for TNF-α in erectile dysfunction

INTRODUCTION

A role for cytokines in the pathophysiology of erectile dysfunction (ED) has emerged. Cytokines induce genes that synthesize other peptides in the cytokine family and several mediators, such as prostanoids, leukotrienes, nitric oxide, bradykinin, reactive oxygen species, and platelet-activating factor, all of which can affect vascular function. Consistent with the fact that the cavernosal tissue is a complex extension of the vasculature, risk factors that affect the vasculature have been shown to affect cavernosal function as well. Accordingly, the penile tissue has been recognized as an early sentinel for atherosclerosis that underlies coronary artery disease and cardiovascular diseases (CVD).

AIM

To review the literature pertaining to the role of tumor necrosis factor-alpha (TNF-α) in ED.

METHODS

PubMed search for pertinent publications on the role of cytokines, particularly TNF-α, in CVD and ED.

MAIN OUTCOME MEASURES

Clinical and experimental evidence demonstrates that TNF-α may play a role in ED.

RESULTS

TNF-α has been shown to play an important role in CVD, mainly due to its direct effects on the vasculature. In addition, high levels of TNF-α were demonstrated in patients with ED. In this review, we present a short description of the physiology of erection and the cytokine network. We focus on vascular actions of TNF-α that support a role for this cytokine as a potential candidate in the pathophysiology of ED, particularly in the context of CVD. A brief overview of its discovery, mechanisms of synthesis, receptors, and its main actions on the systemic and penile vasculature is also presented.

CONCLUSIONS

Considering that ED results from a systemic arterial defect not only confined to the penile vasculature, implication of TNF-α in the pathophysiology of ED offers a humoral linking between CVD and ED.

Anti-tumor necrosis factor-alpha therapy and periodontal parameters in patients with rheumatoid arthritis

BACKGROUND

The aim of this study was to evaluate the influence of anti-tumor necrosis factor-alpha (TNF-alpha) therapy on the clinical and immunologic parameters of the periodontium.

METHODS

Ten patients with rheumatoid arthritis (RA) who routinely received infusions of infliximab, 200 mg (RA+), 10 patients with RA without anti-TNF-alpha therapy (RA-), and 10 healthy controls (C) were included. Clinical parameters, including the plaque index (PI), gingival index (GI), probing depth (PD), clinical attachment loss (AL), and bleeding on probing (BOP), were assessed, and total gingival crevicular fluid (GCF) TNF-alpha level was determined using enzyme-linked immunosorbent assay. Analysis of variance with Scheffe modification and the Pearson correlation test were used for statistical analysis.

RESULTS

The ages of the patients ranged from 22 to 76 years (mean, 50.73 +/- 9.1 years). The mean PI was similar among the groups. However, mean inflammatory parameters in the three groups varied significantly; GI was greater in the RA- group compared to RA+ and C groups (P = 0.0042). The RA+ group exhibited less BOP than RA- and C groups (21.1% +/- 3.0%, 45.9% +/- 6.2%, and 39.1% +/- 7.2%, respectively; P = 0.0146). The mean PD in the RA+ group was shallower than in RA- and C groups (3.22 +/- 0.13 mm, 3.85 +/- 0.22 mm, and 3.77 +/- 0.20 mm, respectively; P = 0.055). Clinical AL in the RA+ group was lower than in RA- and C groups (3.68 +/- 0.11 mm, 4.52 +/- 0.26 mm, and 4.35 +/- 0.24 mm, respectively; P = 0.0273). TNF-alpha levels in the GCF of the RA+ group were the lowest compared to RA- and C groups (0.663, 1.23, and 0.949 ng/site, respectively; P = 0.0401). A significant positive correlation was found between TNF-alpha levels in the GCF and clinical AL (r = 0.448; P = 0.0283).

CONCLUSIONS

Patients with RA receiving anti-TNF-alpha medication had lower periodontal indices and GCF TNF-alpha levels. Thus, suppression of proinflammatory cytokines might prove beneficial in suppressing periodontal diseases.

Evidence for involvement of TNFR1 and TIMPs in pathogenesis of post-kala-azar dermal leishmaniasis

Semi-quantitative RT-PCR was exploited to analyse the intralesional cytokine gene expression in 14 post-kala-azar dermal leishmaniasis (PKDL) and 10 kala-azar (KA) patients. The data provided evidence for both inflammatory and non-inflammatory responses, as reflected by elevated tumour necrosis factor (TNF)-alpha and interleukin (IL)-10 in PKDL lesions compared with normal skin tissue (n = 6). The ratio of TNF-alpha : IL-10 message was 2.66 in PKDL cases, substantially higher than in KA (1.18). Investigation of TNF-alpha receptors (TNFR1 and TNFR2) revealed a significant down-regulation of TNFR1 transcript in both PKDL and KA compared with control. In the presence of elevated levels of TNF-alpha transcript, interference with type 1 effector activity in PKDL may be due to minimal expression of the TNFR1 gene. Investigation of matrix metalloproteinases, known to be induced by TNF-alpha, and the tissue inhibitors of matrix metalloproteinases (TIMPs), provided evidence for the roles of TIMP-1 and TIMP-3 in the pathogenesis of PKDL.

The dual role of p55 tumour necrosis factor-alpha receptor in Actinobacillus actinomycetemcomitans-induced experimental periodontitis: host protection and tissue destruction

Inflammatory immune reactions in response to periodontopathogens are thought to protect the host against infection, but may trigger periodontal destruction. Thus, we examined the mechanisms by which the proinflammatory cytokine tumour necrosis factor (TNF)-alpha modulates the outcome of Actinobacillus actinomycetemcomitans-induced periodontal disease in mice. Our results showed that TNF-alpha receptor p55-deficient mice [p55TNF-knock-out (KO)] developed a less severe periodontitis in response to A. actinomycetemcomitans infection, characterized by significantly less alveolar bone loss and inflammatory reaction. Real-time polymerase chain reaction (PCR) demonstrated that levels of chemokines (CXCL1, 3 and 10; CCL3 and 5) and their receptors (CXCR2 and 3, CCR5) were lower in p55TNF-KO mice, as were matrix metalloproteinase (MMP)-1, 2 and 9 and receptor activator of nuclear factor kB ligand (RANKL) mRNA levels. However, the absence of the TNF-alpha p55 results in an impairment of protective immunity to A. actinomycetemcomitans infection, characterized by increased bacterial load and higher levels of C-reactive protein during the course of disease. Such impaired host response may be the result of the reduced chemoattraction of lymphocytes, neutrophils and macrophages, and reduced inducible nitric oxide synthase expression (iNOS) and myeloperoxidase (MPO) production in periodontal tissues of p55 TNF-KO mice. Our results demonstrate the mechanisms involved determining periodontal disease severity by TNF-alpha receptor p55, and its role in providing immune protection to A. actinomycetemcomitans periodontal infection.

The contribution of interleukin-1 and tumor necrosis factor to periodontal tissue destruction

Interleukin (IL)-1 and tumor necrosis factor (TNF) represent proinflammatory cytokines that stimulate a number of events which occur during periodontal disease. These include the induction of adhesion molecules and other mediators that facilitate and amplify the inflammatory response, the stimulation of matrix metalloproteinase, and bone resorption. The activity of these cytokines coincides with the critical events that occur during periodontal disease, namely, loss of attachment and bone resorption. The use of antagonists to IL-1 and TNF in experimental periodontitis have demonstrated a cause-and-effect relationship between the activity of these cytokines and the spread of an inflammatory front to deeper areas in the connective tissue, loss of connective tissue attachment, osteoclast formation, and loss of alveolar bone. In addition, the loss of fibroblasts that occurs during infection with periodontal pathogens is, in part, mediated by TNF. Thus, much of the damage that occurs during periodontal tissue destruction can be attributed to IL-1 and TNF activity. This destruction may very well represent an overreaction of the host response to periodontal pathogens caused by excessive production of IL-1 and TNF.

Structural development of biological response modifiers based on thalidomide

Thalidomide (N-alpha-phthalimidoglutarimide) is a teratogenic hypnotic/sedative agent which was used widely in the late 1950s and the early 1960s. In spite of its withdrawal from the market because of its severe teratogenicity, there has been a resurgence of interest in the drug in recent years due to its potential usefulness for the treatment of various diseases, including acquired immunodeficiency syndrome (AIDS) and various cancers. It has been revealed that thalidomide elicits pleiotropic effects and is a multi-target drug. Our structural development studies of thalidomide, focusing on tumor necrosis factor-alpha(TNF-alpha) production-regulating activity, anti-androgenic activity, puromycin-sensitive aminopeptidase-inhibiting activity, alpha-glucosidase-inhibiting activity, and inhibitory activities toward some other enzymes, are reviewed in relation to the pharmacological effects of thalidomide.

Soluble antagonists to interleukin-1 (IL-1) and tumor necrosis factor (TNF) inhibits loss of tissue attachment in experimental periodontitis

BACKGROUND, AIMS

Periodontal disease is a significant cause of tooth loss among adults and is characterized by the alteration and permanent destruction of the deeper periodontal tissues. Although the presence of pathologic microbes is required to trigger this process, the amplification and progression of the diseased state is believed to rely heavily on the production of host mediators in response to bacteria or their metabolic products. The inflammatory response is effective in preventing large-scale colonization of the gingival tissues by bacteria that lie in close proximity to the tooth surface or within the gingival sulcus. It has been postulated that the host-response in some individuals may lead to an over-reaction to invading oral pathogens resulting in the destruction of periodontal tissues.

METHODS

Several host-derived mediators are believed to contribute to this response. Two agents considered to be essential in periodontal destruction are interleukin-1 (IL-1) and tumor necrosis factor (TNF). We investigated the role of IL-1 and TNF in the loss of connective tissue attachment in a Macaca fascicularis primate model of experimental periodontitis. Silk ligatures impregnated with the periodontal pathogen, Porphyromonas gingivalis were wrapped around the posterior teeth and the activity of IL-1 and TNF were inhibited by soluble receptors to these proinflammatory cytokines via local injection into interdental papillae.

RESULTS

Histomorphometric analysis indicates that IL-1 and TNF antagonists significantly reduced the loss of connective tissue attachment by approximately 51% and the loss of alveolar bone height by almost 91%, both of which were statistically significant.

CONCLUSION

This investigation demonstrates that the loss of connective tissue attachment and progression of periodontal disease can be retarded by antagonists to specific host mediators such as IL-1 and TNF and may provide a potential treatment modality to combat the disease process.

The role of TNF-alpha during Wallerian degeneration

The role of TNF-alpha in the course of Wallerian degeneration of the sciatic nerve was studied in control and TNF-alpha deficient mice. In control animals, the characteristic phenomena of Wallerian degeneration such as axon and myelin degeneration as well as macrophage recruitment with subsequent myelin removal were observed. In TNF-alpha deficient mice, in contrast, macrophage recruitment into the degenerating nerves was impaired resulting in a delayed myelin removal. However, the myelin phagocytic capacity of macrophages was not affected as it could be demonstrated by a similar myelin load of control and TNF-alpha deficient macrophages. These data indicate that the main function of TNF-alpha during Wallerian degeneration is the induction of macrophage recruitment from the periphery without affecting myelin damage or phagocytosis.

Interleukin-1 and tumor necrosis factor antagonists inhibit the progression of inflammatory cell infiltration toward alveolar bone in experimental periodontitis

Periodontal disease is a significant cause of tooth loss in humans and is one of the most prevalent diseases associated with bone loss. Following bacterial colonization, the gingiva becomes inflamed and, in some cases, progresses to destruction of alveolar bone. To investigate the temporal movement of inflammatory cells toward alveolar bone and the role of interleukin-1 (IL-1) and tumor necrosis factor (TNF) in this process, studies were carried out in a Macaca fascicularis primate model of experimental periodontitis. IL-1 and TNF activity was inhibited by local application of soluble receptors to IL-1 and TNF by injection into interdental papillae. The results indicate that following induction of experimental periodontitis, the front of inflammatory cells progresses toward alveolar bone and is associated with osteoclast formation. These processes are inhibited by blockers to IL-1 and TNF. These studies suggest that the conversion from gingivitis to periodontitis is directly associated with the movement of an inflammatory infiltrate toward alveolar bone, and that this activity is at least partially dependent upon IL-1 and/ or TNF.

Inhibition of NF-kappaB activation in combination with bcl-2 expression allows for persistence of first-generation adenovirus vectors in the mouse liver

NF-kappaB is a key regulator of the innate antiviral immune response, due in part to its transcriptional activation of cytokines and adhesion molecules, which, in turn, function in chemotaxis and activation of inflammatory cells. We reported earlier that viral gene expression in hepatocytes transduced with first-generation (E1-deleted) adenoviruses induced NF-kappaB activation, elevation of serum cytokines, and hepatocellular apoptosis during the first days postinfusion. These events did not occur in mice infused with an adenovirus vector deleted for E1, E2, E3, and late gene expression. In the present study, we used an adenovirus expressing an IkappaBalpha supersuppressor (Ad.IkappaBM) and bcl-2 transgenic mice to unravel the role of virus-induced NF-kappaB activation and apoptosis in the clearance of recombinant adenovirus vectors from the liver. The combined action of IkappaBM and Bcl-2 allowed for vector persistence in livers of C57BL/6 x C3H mice. In the absence of Bcl-2, IkappaBM expression in mouse livers significantly reduced NF-kappaB activation, cytokine expression, leukocyte infiltration, and the humoral immune response against the transgene product; however, this was not sufficient to prevent the decline of vector DNA in transduced cells. Infusion of Ad.IkappaBM caused extended apoptosis predominantly in periportal liver regions, indicating that NF-kappaB activation may protect transduced hepatocytes from apoptosis induced by adenovirus gene products. To confer vector persistence, bcl-2 transgene expression was required to block virus-induced apoptosis if NF-kappaB protection was inactivated by IkappaBM. Expression of gene products involved in early stages of apoptotic pathways was up-regulated in response to virus infusion in bcl-2 transgenic mice, which may represent a compensatory effect. Our study supports the idea that the suppression of innate defense mechanisms improves vector persistence.

Tumor necrosis factor-alpha production-inhibiting activity of phthalimide analogues on human leukemia THP-1 cells and a structure-activity relationship study

N-Substituted phthalimides (2-substituted 1H-isoindole-1,3-diones) were prepared and their inhibitory effects on tumor necrosis factor-alpha (TNF-alpha) production by human leukemia cell line THP-1 stimulated with 12-O-tetradecanoylphorbol 13-acetate (TPA) or okadaic acid (OA) were examined. A structure-activity relationship study of these phthalimide analogues revealed that their inhibitory effects on TPA- and OA-induced TNF-alpha production by THP-1 cells are well correlated to each other, i.e. they may involve the same target molecule(s). An analysis by the use of phthalimide analogue-immobilized affinity gels indicated the existence of several phthalimide-binding proteins in THP-1 cell extract.

The role of Kupffer cell activation and viral gene expression in early liver toxicity after infusion of recombinant adenovirus vectors

Systemic application of first-generation adenovirus induces pathogenic effects in the liver. To begin unraveling the mechanisms underlying early liver toxicity after adenovirus infusion, particularly the role of macrophage activation and expression of viral genes in transduced target cells, first-generation adenovirus or adenovirus vectors that lacked most early and late gene expression were administered to C3H/HeJ mice after transient depletion of Kupffer cells by gadolinium chloride treatment. Activation of NF-kappaB, and the serum levels of the proinflammatory cytokines tumor necrosis factor (TNF) and interleukin-6 (IL-6) were studied in correlation with liver damage, apoptosis, and hepatocellular DNA synthesis. While Kupffer cell depletion nearly eliminated adenovirus-induced TNF release, it resulted in a more robust IL-6 release. These responses were greatly reduced in animals receiving the deleted adenovirus. Although there were quantitative differences, NF-kappaB activation was observed within minutes of first-generation or deleted adenovirus vector administration regardless of the status of the Kupffer cells, suggesting that the induction is related to a direct effect of the virus particle on the hepatocyte. Early liver toxicity as determined by serum glutamic-pyruvic transaminase elevation and inflammatory cell infiltrates appeared to be dependent on adenovirus-mediated early gene expression and intact Kupffer cell function. Kupffer cell depletion had little effect on adenovirus-mediated hepatocyte apoptosis but did increase hepatocellular DNA synthesis. Finally, Kupffer cell depletion decreased the persistence of transgene (human alpha1-antitrypsin [hAAT]) expression that was associated with a more pronounced humoral immune response against hAAT. The elucidation of these events occurring after intravenous adenovirus injection will be important in developing new vectors and transfer techniques with reduced toxicity.