Temporomandibular arthropathies: A retrospective study with histopathological characteristics.

BACKGROUND: To investigate the incidence of temporomandibular arthropathies diagnosed in a university center and to describe their histopathological characteristics. MATERIAL AND METHODS: Temporomandibular arthropathy cases with corresponding slides were selected from an oral and maxillofacial surgical pathology service. Cases of exclusively articular disc disease were not included. RESULTS: The mean age was 31.3 years with a predominance of females (69.7%). Of these diagnoses, 53.6% were unilateral condylar hyperplasia, 17.8% were bony ankylosis, 14.3% were degenerative joint disease, 10.7% were osteochondroma, and 3.6% were synovial chondromatosis. Condylar hyperplasia presented as thick fibrocartilage and cartilage nests in the cancellous bone. Bony ankylosis exhibited lamellar bone and nests of chondrocytes. Degenerative joint disease presented as an irregular layer of fibrocartilage with areas of clustered chondrocytes and calcified cartilage. Osteochondroma of the condyle exhibited hyaline cartilage and areas of new bone formation. Synovial chondromatosis presented as immature cartilaginous tissue and randomly arranged chondrocytes. CONCLUSIONS: The pathological alterations verified in these arthropathies involved diseases that were predominantly proliferative, i.e., unilateral condylar hyperplasia, osteochondroma and synovial chondromatosis of the tumor or pseudotumor type and bony ankylosis associated with callus formation of the reparative type, and less frequent degenerative changes for which the disease is so named.

Proliferation is a prerequisite for bacterial superantigen-induced T cell apoptosis in vivo.

Staphylococcal enterotoxin B (SEB) is a bacterial superantigen that binds to major histocompatibility complex class II molecules and selectively interacts with T cells that bear certain T cell receptor (TCR) V beta domains. Administration of SEB in adult mice results in initial proliferation of V beta 8+ T cells followed by a state of unresponsiveness resulting from a combination of clonal deletion and clonal anergy in the SEB-reactive population. At this time, it is unclear what relationship exists between the T cells that have proliferated and those that have been deleted or have become anergic. Here we show that only a fraction of the potentially reactive V beta 8+ T cells proliferate in response to SEB in vivo, and that all the cells that have proliferated eventually undergo apoptosis. Virtually no apoptosis can be detected in the nonproliferating V beta 8+ T cells. These data demonstrate a causal relationship between proliferation and apoptosis in response to SEB in vivo, and they further indicate that T cells bearing the same TCR V beta segment can respond differently to the same superantigen. The implications of this differential responsiveness in terms of activation and tolerance are discussed.

Peripheral T cells undergoing superantigen-induced apoptosis in vivo express B220 and upregulate Fas and Fas ligand.

Staphylococcal enterotoxin B (SEB) is a bacterial superantigen (SAg) that predominantly interacts with V(beta)8+ T cells. In vivo treatment of mice with SEB leads to an initial increase in the percentage of V(beta)8+ T cells, followed by a decrease in the numbers of these cells, eventually reaching lower levels than those found before treatment with the SAg. This decrease is due to apoptosis of the SEB-responding cells. In the present study, we use the distinct light scattering characteristics of apoptotic cells to characterize T cells that are being deleted in response to SEB in vivo. We show that dying, SEB-reactive T cells express high levels of Fas and Fas ligand (Fas-L), which are implicated in apoptotic cell death. In addition, the B cell marker B220 is upregulated on apoptotic cells. Moreover, we show that the generation of cells with an apoptotic phenotype is severely impaired in response to SEB in functional Fas-L-deficient mutant gld mice, confirming the role of the Fas pathway in SAg mediated peripheral deletion in vivo.

Cytokine production by cells in cerebrospinal fluid during experimental allergic encephalomyelitis in SJL/J mice.

Cytokine production by T cells in the cerebrospinal fluid (CSF) and central nervous system (CNS) of SJL/J mice during myelin basic protein (MBP)-induced experimental allergic encephalomyelitis (EAE) was examined. Reverse transcriptase/polymerase chain reaction (RT/PCR) was used to measure interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) mRNA levels from perfused CNS tissue (brain and spinal cord) and from cells isolated from CSF. Animals were grouped according to EAE severity, ranging from asymptomatic (adjuvant only) to severe disease (paralysis or severe paresis). Cytokine signals, normalized to actin, were almost undetectable in control tissues, and only slightly elevated in whole CNS tissue from animals with mild EAE. Both cytokine messages were strongly upregulated in CNS tissues derived from severely affected animals, consistent with previous observations correlating disease progression with infiltration by memory/effector CD4+ T cells, the major source of these cytokines. This cytokine upregulation was specific to the CNS, since other organs from the same animals did not express significant levels of IL-2 and IFN-gamma. CSF was obtained from the cisterna magna of unperfused mice and verified as such by absence of red blood cells (RBCs) and by immunoglobulin concentration orders of magnitude lower than in serum. Cytokine message was measured in RNA isolated from cells in CSF. Levels of IL-2 and IFN-gamma mRNA in CSF cells were significantly elevated in mild EAE and strongly upregulated in severe disease, correlating with those in total CNS tissue. These results confirm the CSF as representative of the immune status of the CNS and indicate a role for IL-2 and IFN-gamma in inflammatory CNS disease.

LAMTOR1 depletion induces p53-dependent apoptosis via aberrant lysosomal activation.

Lysosomal regulation is a poorly understood mechanism that is central to degradation and recycling processes. Here we report that LAMTOR1 (late endosomal/lysosomal adaptor, MAPK and mTOR activator 1) downregulation affects lysosomal activation, through mechanisms that are not solely due to mTORC1 inhibition. LAMTOR1 depletion strongly increases lysosomal structures that display a scattered intracellular positioning. Despite their altered positioning, those dispersed structures remain overall functional: (i) the trafficking and maturation of the lysosomal enzyme cathepsin B is not altered; (ii) the autophagic flux, ending up in the degradation of autophagic substrate inside lysosomes, is stimulated. Consequently, LAMTOR1-depleted cells face an aberrant lysosomal catabolism that produces excessive reactive oxygen species (ROS). ROS accumulation in turn triggers p53-dependent cell cycle arrest and apoptosis. Both mTORC1 activity and the stimulated autophagy are not necessary to this lysosomal cell death pathway. Thus, LAMTOR1 expression affects the tuning of lysosomal activation that can lead to p53-dependent apoptosis through excessive catabolism.

dsRNA induces apoptosis through an atypical death complex associating TLR3 to caspase-8.

Toll-like receptor 3 (TLR3) is a pattern-recognition receptor known to initiate an innate immune response when stimulated by double-stranded RNA (dsRNA). Components of TLR3 signaling, including TIR domain-containing adapter inducing IFN-α (TRIF), have been demonstrated to contribute to dsRNA-induced cell death through caspase-8 and receptor interacting protein (RIP)1 in various human cancer cells. We provide here a detailed analysis of the caspase-8 activating machinery triggered in response to Poly(I:C) dsRNA. Engagement of TLR3 by dsRNA in both type I and type II lung cancer cells induces the formation of an atypical caspase-8-containing complex that is devoid of classical death receptors of the TNFR superfamily, but instead is physically associated to TLR3. The recruitment of caspase-8 to TLR3 requires RIP1, and is negatively modulated by cellular inhibitor of apoptosis protein (cIAP)2-TNF receptor-associated factor (TRAF)2-TNFR-associated death domain (TRADD) ubiquitin ligase complex, which regulates RIP1 ubiquitination. Intriguingly, unlike Fas- or TRAILR-dependent death signaling, caspase-8 recruitment and activation within the TLR3 death-signaling complex appears not to be stringently dependent on Fas-associated with death domain (FADD). Our findings uncover a novel aspect of the molecular mechanisms involved during apoptosis induced by the innate immune receptor TLR3 in cancer cells.

A highly sensitive in vitro infection assay to explore early stages of mouse mammary tumor virus infection.

Mouse mammary tumor virus (MMTV) infection of adult mice induces a strong response to superantigen (Sag) in their draining lymph nodes, which results from the presentation of Sag by MMTV-infected B cells to Sag-reactive T cells. To date, infection with physiologically relevant doses of MMTV can be detected in vivo only after several days of Sag-mediated T-cell-dependent amplification of infected B cells. Furthermore, no efficient in vitro system of detecting MMTV infection is available. Such a model would allow the dissection of the early phase of infection, the assessment of the contributions of different cell types, and the screening of large panels of molecules for their potential roles in infection and Sag response. For these reasons, we have established an in vitro model for detecting infection which is as sensitive and reproducible as the in vivo model. We found that the viral envelope (Env) protein is crucial for target cell infection but not for presentation of Sag. Furthermore, we show that infection of purified B cells with MMTV induces entry of Sag-responsive T cells into the cell cycle, while other professional antigen-presenting cells, such as dendritic cells, are much less efficient in inducing a response.

Inflammatory cytokines in the brain: does the CNS shape immune responses?

Immune responses in the central nervous system (CNS) have traditionally been regarded as representing the intrusion of an unruly, ill-behaved mob of leukocytes into the well-ordered and organized domain of thought and reason. However, results accumulated over the past few years suggest that, far from being an immunologically privileged organ, T lymphocytes may be regular and frequent visitors to the CNS, for purposes of immune surveillance. Here, Trevor Owens and colleagues propose that the brain itself can regulate or shape immune responses therein. Furthermore, given that the immune cells may be subverted to autoimmunity, they suggest that the study of inflammatory autoimmune disease in the brain may shed light on the ability of the local environment to regulate immune responses.

Impaired fetal thymocyte development after efficient adenovirus-mediated inhibition of NF-kappa B activation.

We introduce a new experimental system combining adenovirus-mediated gene transfer and fetal thymic organ culture (FTOC). This system allowed us to efficiently express in developing thymocytes a mutant form of the NF-kappa B inhibitor I kappa B alpha (mut-I kappa B) and to study the maturation defects occurring when NF-kappa B activation is inhibited during fetal development. Fetal thymocytes infected with adenovirus containing mut-I kappa B were found to develop normally until the CD44-CD25+, CD4-CD8- double-negative stage, while production of more mature double-positive and single-positive populations was strongly decreased. Proliferation, as measured by the percentage of cells in cycle appeared normal, as did rearrangement and expression of the TCR beta-chain. However, apoptosis was much higher in FTOC infected with adenovirus containing mut-I kappa B than in FTOC infected with a control virus. Taken together, these results suggest that NF-kappa B plays a crucial role in ensuring the differentiation and survival of thymocytes in the early stages of their development.

Increased severity of experimental autoimmune encephalomyelitis, chronic macrophage/microglial reactivity, and demyelination in transgenic mice producing tumor necrosis factor-alpha in the central nervous system.

Tumor necrosis factor-alpha (TNF-alpha) is an inflammatory cytokine implicated in a number of autoimmune diseases. Apoptotic cell death is induced by TNF-alpha in vitro, and has been suggested as one cause of autoimmune pathology, including autoimmune demyelinating diseases where oligodendrocytes are a target of immune attack. TNF-alpha also regulates macrophage activity which could contribute to autoimmune inflammation. We have expressed TNF-alpha at disease-equivalent levels in the central nervous system of transgenic mice, using a myelin basic protein (MBP) promoter. These mice were normal and showed no spontaneous pathology, but they developed experimental autoimmune encephalomyelitis (EAE) with greater severity than nontransgenic controls when immunized with MBP in adjuvant. Unlike nontransgenic controls, EAE then progressed to a nonabating demyelinating disease. Macrophage/microglial reactivity was evident in demyelinating lesions in spinal cord, but T cells were not detected during chronic disease. The participation of TNF-alpha in the demyelinating process is thus more probably due to the perpetuation of macrophage/microglial activation than to direct cytotoxicity of myelin or oligodendroglia.

Viral superantigen-induced negative selection of TCR transgenic CD4+ CD8+ thymocytes depends on activation, but not proliferation.

T-cell negative selection, a process by which intrathymic immunological tolerance is induced, involves the apoptosis-mediated clonal deletion of potentially autoreactive T cells. Although different experimental approaches suggest that this process is triggered as the result of activation-mediated cell death, the signal transduction pathways underlying this process is not fully understood. In the present report we have used an in vitro system to analyze the cell activation and proliferation requirements for the deletion of viral superantigen (SAg)-reactive Vbeta8.1 T-cell receptor (TCR) transgenic (TG) thymocytes. Our results indicate that in vitro negative selection of viral SAg-reactive CD4+ CD8+ thymocytes is dependent on thymocyte activation but does not require the proliferation of the negatively signaled thymocytes.

Fas ligand-induced apoptosis of infected human macrophages reduces the viability of intracellular Mycobacterium tuberculosis.

Mycobacterium tuberculosis-specific cytolytic activity is mediated mostly by CD4+CTL in humans. CD4+CTL kill infected target cells by inducing Fas (APO-1/CD95)-mediated apoptosis. We have examined the effect of Fas ligand (FasL)-induced apoptosis of human macrophages infected in vitro with M. tuberculosis on the viability of the intracellular bacilli. Human macrophages expressed Fas and underwent apoptosis after incubation with soluble recombinant FasL. In macrophages infected either with an attenuated (H37Ra) or with a virulent (H37Rv) strain of M. tuberculosis, the apoptotic death of macrophages was associated with a substantial reduction in bacillary viability. TNF-induced apoptosis of infected macrophages was coupled with a similar reduction in mycobacterial viability, while the induction of nonapoptotic complement-induced cell death had no effect on bacterial viable counts. Infected macrophages also showed a reduced susceptibility to FasL-induced apoptosis correlating with a reduced level of Fas expression. These data suggest that apoptosis of infected macrophages induced through receptors of the TNF family could be an immune effector mechanism not only depriving mycobacteria from their growth environment but also reducing viable bacterial counts by an unknown mechanism. On the other hand, interference by M. tuberculosis with the FasL system might represent an escape mechanism of the bacteria attempting to evade the effect of apoptosis.

Efficient adenoviral transfer of NF-kappaB inhibitor sensitizes melanoma to tumor necrosis factor-mediated apoptosis.

It has been suggested that the in vitro cytotoxicity of tumor necrosis factor (TNF) toward a number of transformed cell lines could make it a useful agent for anti-tumor therapy. However, many tumor cell lines are resistant to TNF-induced cell death. It has been shown that transcription factors of the NF-kappaB family, which are themselves activated by TNF, could protect cells against apoptotic cell death. To test whether melanoma cells, which are normally resistant to TNF-mediated killing, can be made susceptible by inhibiting the activation of NF-kappaB, we generated a recombinant adenovirus expressing a dominant mutant form of IkappaB alpha under the control of a CMV promoter. We show here that adenovirus-mediated inhibition of NF-kappaB function rendered melanoma cells susceptible to the cytotoxic effects of TNF, and thus that NF-kappaB-inhibiting adenoviruses could become useful adjuvants in TNF-based anti-tumor therapies.

Cutting edge: apoptosis of superantigen-activated T cells occurs preferentially after a discrete number of cell divisions in vivo.

Staphylococcal enterotoxins are bacterial products that display superantigen activity in vitro as well as in vivo. For instance, staphylococcal enterotoxin B (SEB) polyclonally activates T cells that bear the Vbeta8 gene segment of the TCR. SEB-activated T cells undergo a burst of proliferation that is followed by apoptosis. Using an in vivo adaptation of a fluorescent cell division monitoring technique, we show here that SEB-activated T cells divide asynchronously, and that apoptosis of superantigen-activated T cells is preferentially restricted to cells which have undergone a discrete number of cell divisions. Collectively, our data suggest that superantigen-activated T cells are programmed to undergo a fixed number of cell divisions before undergoing apoptosis. A delayed death program may provide a mechanistic compromise between effector functions and homeostasis of activated T cells.

The involvement of an ATP-gated ion channel, P(2X1), in thymocyte apoptosis.

In the immune system, apoptosis is involved in intrathymic elimination of self-reactive thymocytes and in peripheral T cell tolerance to exogenous antigens. Here, we describe the role in T cell apoptosis of P(2x1), a nonselective cation channel activated by ATP. P(2X1) molecules are up-regulated in thymocytes during dexamethasone-induced apoptosis, and antagonists to these receptors protect thymocytes from cell death. Moreover, P(2X1) mRNA and protein levels increase in thymocytes induced to die in vivo by the superantigen staphylococcal enterotoxin B. In contrast, T cells undergoing apoptosis in the periphery do not express P(2X1). The demonstration that P(2X1) ion channels play a role in the apoptosis of thymocytes but not peripheral T cells illustrates a novel mechanism contributing to thymocyte cell death and opens new possibilities for investigating clonal deletion in the thymus.

What's new in the field of cancer vaccines?

The observation that in some cases tumors undergo spontaneous regression concomitantly with autoimmune manifestations has been interpreted as an indication of the involvement of the immune system in tumor rejection. This raised the conceptual possibility that the immune system could be used against the tumor. However, since tumor cells are poorly immunogenic by themselves, early attempts to develop immune-based approaches for cancer therapy saw the use of tumor cells transduced with genes coding for cytokines or costimulatory molecules to enhance in vivo immunity. The identification of cytotoxic T lymphocyte (CTL)-defined tumor-associated antigens has allowed the development of new strategies for cancer immunotherapy. Novel adjuvants have been identified, and different modes of antigen delivery were devised which aim at inducing efficient CTL responses in patients. This review will discuss some of what is currently considered as relevant aspects of antitumor immunization.

TNF-alpha expression by resident microglia and infiltrating leukocytes in the central nervous system of mice with experimental allergic encephalomyelitis. Regulation by Th1 cytokines.

The inflammatory cytokines IFN-gamma and TNF-alpha have been demonstrated in various autoimmune diseases, and are thought to participate in the induction and pathogenesis of disease. TFN-alpha is a cytopathic cytokine that is cytotoxic for oligodendrocytes in vitro and has been implicated in the pathology of multiple sclerosis and its animal model experimental allergic encephalomyelitis (EAE). We used reverse transcriptase (RT)-PCR to study the kinetics, cellular source, and regulation of cytokine gene expression in the central nervous system (CNS) of SJL/J mice with myelin basic protein-induced EAE at different stages of the disease. The expression of CD3, IL-2, IFN-gamma, and TNF-alpha mRNA was barely detectable in the CNS of unmanipulated mice or mice that were immunized with adjuvant but showed no symptoms. These mRNAs were readily detectable in the CNS of mice during peak disease, then coordinately dropped to background levels during remission. Analysis of cells isolated from the CNS of mice with acute EAE showed that the Th1 cytokines, IL-2 and IFN-gamma, were produced by infiltrating CD4+ T cells. In contrast, TNF-alpha was predominantly transcribed by non-T mononuclear CNS cells, the majority of which were identified as microglia and macrophages by their Mac-1 phenotype. Microglia could be discriminated by their low expression of CD45. Incubation of freshly derived, adult microglia from normal, uninfiltrated, CNS with activated Th1 supernatant induced the production of TNF-alpha mRNA. Therefore, TNF-alpha is made by both CNS-resident microglia and infiltrating macrophages during EAE, and this production is tightly controlled by cytokines secreted by infiltrating CD4+ T cells.

Selective enrichment of Th1 CD45RBlow CD4+ T cells in autoimmune infiltrates in experimental allergic encephalomyelitis.

The cytokine effector status of CD4+ T cells from lymph nodes (LN) and the central nervous system (CNS) of SJL/J mice immunized with autoantigen in adjuvant for the induction of experimental allergic encephalomyelitis (EAE) was compared. CD4+ T cells were FACS sorted based on the levels of expression of the activation marker CD45RB. Low levels of expression of this surface marker are induced by antigen recognition and are associated with 'effector' T cell function. Reverse transcriptase polymerase chain reaction (PCR) was used to analyze the expression of different T cell cytokine genes in the sorted populations. CD45RBlow cells constituted a minority of CD4+ cells in the LN and expressed elevated levels of IL-2, IFN-gamma, and IL-4 mRNA, whereas the CD45RBlow CD4+ population did not express detectable message for these cytokines under linear PCR conditions. By contrast to the LN, CD4+ cells from the CNS were predominantly CD45RBlow and expressed readily detectable levels of IL-2 and IFN-gamma mRNA, but almost no IL-4 transcription could be detected. IL-4 mRNA levels in CNS were 100- to 250-fold lower than in LN. Also, IL-4 message could not be detected in the CNS 1 week after remission. A cytokine-specific immunocytochemical single cell staining technique was used to enumerate cytokine-producing cells in LN cell populations and in CNS infiltrates. Between 1 and 5% cells in isolated LN cells produced detectable IL-2 and IFN-gamma. By contrast, the frequency of cytokine-producing cells stained in perivascular infiltrates in frozen sections from the brains of animals with active EAE was 10-fold higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of B220 on activated T cell blasts precedes apoptosis.

Superantigens are bacterial or viral products that polyclonally activate T cells bearing certain TCR beta chain variable elements. For instance, Vbeta8+ T cells proliferate in response to staphylococcal enterotoxin B (SEB) in vivo and then undergo Fas- and/or TNF-mediated apoptosis. We have recently shown that apoptotic SEB-reactive T cells express the B cell marker B220. Here we report the identification of a novel subset of CD4+ B220+ T cell blasts that are the precursors of these apoptotic cells in SEB-immunized mice. Moreover, we show that the CD4- CD8- B220+ T cells that accumulate in the lymphoid organs of Fas ligand-defective gld mice stably express a form of the B220 molecule which exhibits biochemical similarities to that expressed by activated wild-type T cells, but is distinct from that displayed on the surface of B cells. Surprisingly, we also find a population of CD4+ B220+ pre-apoptotic T cells in FasL-defective gld mice, arguing that these cells can be generated in a Fas-independent fashion. Collectively, our data support a general model whereby upon activation, T cells up-regulate B220 before undergoing apoptosis. When the apoptotic mechanisms are defective, T cells presumably down-regulate their coreceptor molecules but retain expression of B220 as they accumulate in lymphoid organs.