Pregnancy-associated, lymphocyte-derived suppressor factor inhibits protein kinase C activity

Phorbol-12-myristate 13-acetate inhibits Nephronectin gene expression via Protein kinase C alpha and c-Jun/c-Fos transcription factors

Nephronectin (Npnt) is an extracellular matrix protein and ligand of integrin α₈β₁ known to promote differentiation of osteoblasts. A search for factors that regulate Npnt gene expression in osteoblasts revealed that phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (PKC), had a strong effect to suppress that expression. Research was then conducted to elucidate the signaling pathway responsible for regulation of Npnt gene expression by PMA in osteoblasts. Treatment of MC3T3-E1 cells with PMA suppressed cell differentiation and Npnt gene expression. Effects were noted at a low concentration of PMA, and were time- and dose-dependent. Furthermore, treatment with the PKC signal inhibitor Gö6983 inhibited down-regulation of Npnt expression, while transfection with small interfering RNA (siRNA) of PKCα, c-Jun, and c-Fos suppressed that down-regulation. The present results suggest regulation of Npnt gene expression via the PKCα and c-Jun/c-Fos pathway.

Effectiveness of seasonal trivalent influenza vaccination against hospital-attended acute respiratory infections in pregnant women: A retrospective cohort study

BACKGROUND

Pregnant women are at risk of serious influenza infection. Although previous studies indicate maternal influenza vaccination can prevent hospitalisation in young infants, there is limited evidence of the effect in mothers.

METHODS

A cohort of 34,701 pregnant women delivering between 1 April 2012 and 31 December 2013 was created using birth records. Principal diagnosis codes from hospital emergency department (ED) and inpatient records were used to identify episodes of acute respiratory illness (ARI) during the 2012 and 2013 southern hemisphere influenza seasons. Cox regression models were used to calculate adjusted hazard ratios (aHRs) by maternal vaccination status, controlling for Indigenous status, socioeconomic level, medical conditions, and week of delivery.

RESULTS

3,007 (8.7%) women received a seasonal influenza vaccine during pregnancy. Vaccinated women were less likely to visit an ED during pregnancy for an ARI (9.7 visits per 10,000 person-days vs. 35.5 visits per 10,000 person-days; aHR: 0.19, 95% CI: 0.05-0.68). Vaccinated women were also less likely to be hospitalised with an ARI compared to unvaccinated women (16.2 hospitalisations per 10,000 person-days vs. 34.0 hospitalisations per 10,000 person-days; aHR: 0.35, 95% CI: 0.13-0.97).

CONCLUSIONS

Influenza vaccination during pregnancy was associated with significantly fewer hospital attendances for ARI in pregnant women.

C-fos and c-jun expression in human endometrium and myometrium

Estrogen is a mitogen in human endometrium and is considered to be responsible also for myometrial cell proliferation. Signalling pathways of estrogen action in these tissues are not known. In various other estrogen responsive cells, estrogen induces transient expressions of c-fos and c-jun mRNAs. We examined c-fos and c-jun mRNA expressions by Northern blotting in paired samples of endometrium, myometrium and leiomyoma tissues obtained from women under various hormonal environments as well as of endometrium and myometrium at term pregnancy. In nonpregnant endometria, strong expressions of c-fos (2.2 kb) and of c-jun (2.7 kb and 3.2 kb) were detected both in the follicular and luteal phase of the menstrual cycle, and the c-fos expression was significantly stronger in proliferative phase endometrium than in the adjacent myometrium. In most of the myometrial and leiomyoma tissue samples the signals for both protooncogenes were weak, and there were no systematic differences in the expressions between normal myometrium and myomatous tissue. In pregnant endometrium and myometrium, both the c-fos and c-jun mRNA expressions were nearly undetectable, and in pregnant endometrium expressions were significantly lower than those in nonpregnant endometrium. Also in late pregnancy myometria, the expression of c-jun was significantly lower than in nonpregnant tissues. These data suggest that c-fos and c-jun activation may be a part of estrogen-induced signal transduction in the endometrium, and that in term pregnancy endometrium this signalling pathway is inhibited. Due to the strong expression of c-jun and c-fos both in the proliferative and secretory phase endometrium, it is likely that these protooncogenes are related to functions other than epithelial cell proliferation in human endometrium. The weak expressions of c-fos and c-jun in the myometrium and in leiomyomata suggest that signalling pathways mediating steroid hormone action in endometrium and myometrium are different.

Aged lymphocyte proliferation following incorporation and retention of dietary omega-3 fatty acids

T cell activation involves events at the plasma membrane; therefore, molecules such as long chain omega-3 fatty acids that alter the structure of the plasma membrane may affect the activation of aged T cells. In this project we investigated whether the incorporation of omega-3 fatty acids (from fish oil), in the presence of vitamin E, improves age-diminished T cell proliferation. Young and old mice were fed diets rich in either fish (menhaden) oil or saturated fat for various lengths of time. Splenocytes were harvested from these mice and stimulated in culture with either mitogen or the antigen keyhole limpet hemocyanin (for a secondary response); proliferation was estimated by [3H]thymidine incorporation. We found no discernible effect of dietary omega-3 fatty acids (with vitamin E supplementation) on lymphocyte proliferation stimulated by the mitogens concanavalin A or phytohemagglutinin. We did, however, find that the saturated fat diet and the menhaden oil diet in young mice lowered protein kinase C activities in the particulate fractions of spleen cells when compared to chow-fed mice. Middle-aged and old mice were less affected by the experimental diets than young mice, but they demonstrated decreased protein kinase C activity as well. These alterations did not affect the ability of splenocytes to respond to mitogenic stimulation. Fatty acid analysis revealed that lymphocytes from mice fed saturated fat for 8.5 months retained significant amounts of the omega-3 fatty acid docosahexaenoic acid, despite the lack of dietary omega-3 fatty acids. However, when aged (but not young) lymphocytes were clonally expanded by antigen in vivo in the presence of dietary omega-3 fatty acids, they produced a greater secondary proliferative response than old lymphocytes expanded during a saturated fat diet. Although our results suggest that omega-3 fatty acids may enhance aged lymphocyte proliferation, the tenacious retention of these fatty acids makes comparison with omega-3-depleted lymphocytes difficult.