Conditional TNF-α Overexpression in the Tooth and Alveolar Bone Results in Painful Pulpitis and Osteitis.

Tumor necrosis factor-α (TNF-α) is a proalgesic cytokine that is commonly expressed following tissue injury. TNF-α expression not only promotes inflammation but can also lead to pain hypersensitivity in nociceptors. With the established link between TNF-α and inflammatory pain, we identified its increased expression in the teeth of patients affected with caries and pulpitis. We generated a transgenic mouse model (TNF-α(glo)) that could be used to conditionally overexpress TNF-α. These mice were bred with a dentin matrix protein 1 (DMP1)-Cre line for overexpression of TNF-α in both the tooth pulp and bone to study oral pain that would result from subsequent development of pulpitis and bone loss. The resulting DMP1/TNF-α(glo) mice show inflammation in the tooth pulp that resembles pulpitis while also displaying periodontal bone loss. Inflammatory infiltrates and enlarged blood vessels were observed in the tooth pulp. Pulpitis and osteitis affected the nociceptive neurons innervating the orofacial region by causing increased expression of inflammatory cytokines within the trigeminal ganglia. With this new mouse model morphologically mimicking pulpitis and osteitis, we tested it for signs of oral pain with an oral function assay (dolognawmeter). This assay/device records the time required by a mouse to complete a discrete gnawing task. The duration of gnawing required by the DMP1/TNF-α(glo) mice to complete the task was greater than that for the controls; extended gnaw time in a dolognawmeter indicates reduced orofacial function. With the DMP1/TNF-α(glo) mice, we have shown that TNF-α expression alone can produce inflammation similar to pulpitis and osteitis and that this mouse model can be used to study dental inflammatory pain.

Cyclin-dependent kinase 5 activator p35 over-expression and amyloid beta synergism increase apoptosis in cultured neuronal cells.

Alzheimer disease (AD) is a neurodegenerative disorder characterized by neuronal loss, dementia and pain. Two main protein aggregates, extracellular (senile plaques, SP) and intracellular (neurofibrillary tangles, NFT), are associated with AD. NFT are mainly composed of hyperphosphorylated microtubule-associated protein tau. Nowadays several protein kinases have been implicated in the phosphorylation of tau, including glycogen synthase kinase 3 beta (GSK3beta), MAP kinase, protein kinase A and cyclin-dependent kinase 5 (Cdk5). A deregulation in the activity of Cdk5 has been postulated to participate in the abnormal tau hyperphosphorylation in AD. Activation of Cdk5 occurs after its association with p35, a neuron-specific activator, predominantly in the nervous system. Therefore, in this study we used the tetracycline transactivator system to increase p35/GFP in neuronal cells, treated with amyloid beta 1-42 (Abeta(1-42)) peptide. These cells showed an increase of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and cleaved caspase-3 staining, indicating increased apoptosis of neuronal cells. This effect could be reversed by the addition of tetracycline in the culture medium, suggesting synergistic effects of p35 over-expression and Abeta treatment in the apoptosis of neuronal cells. These results represent a linkage between amyloidogenic and cdk5 pathways leading to apoptosis of neuronal cells.

Expression of intercellular adhesion molecule 1 (ICAM-1) on the human oviductal epithelium and mediation of lymphoid cell adherence.

The epithelium of the human oviduct expresses the major histocompatibility complex (MHC) class II and shows endocytic properties towards luminal antigens. Therefore, the epithelial cells might behave as antigen-presenting cells, inducing a local immune response. The activation of antigen-specific T cells not only requires presentation of the peptide antigen by MHC class II, but also the presence of co-stimulatory molecules in the antigen-presenting cells. Therefore, the expression of the intercellular adhesion molecule 1 (ICAM-1) was examined in the epithelium of the human oviduct. Most oviducts showed epithelial ICAM-1 expression, as assessed by immunocytochemistry, western blot analysis and RT-PCR assay, and the expression was restricted to the luminal border of ciliated and secretory cells. Interferon gamma, interleukin 1 and lipopolysaccharide treatments increased the percentage of ICAM-1-positive cells in primary cultures, indicating that the expression of ICAM-1 in the oviduct might be upregulated in vivo by inflammatory cytokines or bacterial infections. Binding assays between allogenic phytohaemagglutinin-activated lymphocytes and epithelial monolayers expressing ICAM-1 demonstrated that this molecule stimulated lymphocyte adherence. The presence of ICAM-1, in addition to MHC class II, supports the putative role of the oviductal epithelium in antigen presentation. The exclusive apical distribution of ICAM-1 indicates that T-cell activation would occur in a polarized manner. Binding of lymphoid cells to the surface of the oviductal epithelium may help to retain these immune cells that are required for the clearance of pathogens.

Lactation inhibits the potentiating effect of galanin upon the GnRH-induced LH release observed in diestrous-1 rat.

Recent demonstrations of no changes in hypothalamic gonadotropin releasing hormone (GnRH) gene expression and GnRH levels detected at the pituitary gland in diestrous and lactating rats, indicate that lactational hypogonadotropism in this species is not associated with inhibition of hypothalamic GnRH synthesis and secretion. Hypothalamic galanin potentiates GnRH effects on luteinizing hormone (LH) secretion in male and cycling rats. To explore the interaction between GnRH and galanin during lactation, we studied in vitro the effects of pulsatile stimulation with those peptides upon LH synthesis and secretion from rat pituitaries on diestrous 1 or day 10 of lactation. Hemipituitaries were separately incubated in 1 ml Dulbecco's Minimal Essential Medium supplemented with 1% penicillin-streptomycin and fetal calf serum, at 37 degrees C in 5% CO2-air. The hemipituitaries were stimulated during 12 h with hourly pulses, 6 min each, of (a) gonadotropin releasing hormone (GnRH 25 ng/pulse), (b) rat galanin (600 ng/pulse), (c) GnRH plus galanin, or (d) saline. Medium was collected before each pulse to determine LH by radioimmunoassay. After the 12 h pulsatile regime total RNA was extracted and both actin and beta-LH mRNA were determined by reverse transcriptase polymerase chain reaction. There was a significant stimulation of LH secretion by GnRH (ANOVA, p < 0.001) without significant differences between diestrous and lactation pituitaries. Galanin alone did not modify LH secretion but it potentiated the effect of GnRH upon pituitaries from diestrous (p = 0.036) but not lactating rats. Neither peptide alone or its combination modified pituitary beta-LH mRNA levels. Results show that galanin regulates differently the secretion and synthesis of LH at the pituitary level. The disappearance of galanin-induced potentiation of GnRH effects upon LH secretion during lactation might contribute to the hypogonadotropism of lactation in the rat.