Tumor-Shed PGE2 Impairs IL2Rγc-Signaling to Inhibit CD4+ T Cell Survival: Regulation by Theaflavins

BACKGROUND:Many tumors are associated with decreased cellular immunity and elevated levels of prostaglandin E2 (PGE2), a known inhibitor of CD4+ T cell activation and inducer of type-2 cytokine bias. However, the role of this immunomodulator in the survival of T helper cells remained unclear. Since CD4+ T cells play critical roles in cell-mediated immunity, detail knowledge of the effect tumor-derived PGE2 might have on CD4+ T cell survival and the underlying mechanism may, therefore, help to overcome the overall immune deviation in cancer. METHODOLOGY/PRINCIPAL FINDINGS:By culturing purified human peripheral CD4+ T cells or Jurkat cells with spent media of theaflavin- or celecoxib-pre-treated MCF-7 cells, we show that tumor-shed PGE2 severely impairs interleukin 2 receptor gammac (IL2Rgammac)-mediated survival signaling in CD4+ T cells. Indeed, tumor-shed PGE2 down-regulates IL2Rgammac expression, reduces phosphorylation as well as activation of Janus kinase 3 (Jak-3)/signal transducer and activator of transcription 5 (Stat-5) and decreases Bcl-2/Bax ratio thereby leading to activation of intrinsic apoptotic pathway. Constitutively active Stat-5A (Stat-5A1 6) over-expression efficiently elevates Bcl-2 levels in CD4+ T cells and protects them from tumor-induced death while dominant-negative Stat-5A over-expression fails to do so, indicating the importance of Stat-5A-signaling in CD4+ T cell survival. Further support towards the involvement of PGE2 comes from the results that (a) purified synthetic PGE2 induces CD4+ T cell apoptosis, and (b) when knocked out by small interfering RNA, cyclooxygenase-2 (Cox-2)-defective tumor cells fail to initiate death. Interestingly, the entire phenomena could be reverted back by theaflavins that restore cytokine-dependent IL2Rgammac/Jak-3/Stat-5A signaling in CD4+ T cells thereby protecting them from tumor-shed PGE2-induced apoptosis. CONCLUSIONS/SIGNIFICANCE:These data strongly suggest that tumor-shed PGE2 is an important factor leading to CD4+ T cell apoptosis during cancer and raise the possibility that theaflavins may have the potential as an effective immunorestorer in cancer-bearer

Računarski program za procenu troškova poljoprivrednih mašina

A user-friendly computer program is developed in Visual Basic environment to determine the all types of machinery costs on hour and hectare basis. The program is also capable to compute breakeven area and time of use of machines to get back return on investment. The input parameters of the developed program are mainly initial price, life of machine, rate of interest, fuel cost, labor wages etc. for power source as well as implement. The total cost is being calculated in two heads namely fixed and variable cost. The fixed cost consists of depreciation, interest, taxes, housing and insurance cost, while variable costs includes fuel, lubrication, wages, repair and maintenance cost. The developed program successfully calculates the cost of operation in rupees per hour and in rupees per hectare of different combinations of power sources and implements. The breakeven analysis of any combination of the power source and implement can also be analyzed. This program can be a useful tool for suggesting the farmers in purchasing a machine as well as in deciding the custom hiring rates etc. This can also help to entrepreneurs who are engaged in custom hiring services to decide the hiring rate of different machinery on the basis of breakeven analysis.Kompjuterski program prilagođen korisniku je razvijen u Visual Basic okruženju da odredi sve tipove troškova mašina po času i hektaru. Program takođe omogućuje izračunavanje oblasti izjednačenja i vreme upotrebe mašina do povraćaja investicije. Ulazni parametric razvijenog programa su uglavnom početna cena, radni vek mašine, kamatna stopa, troškovi goriva, troškovi rada itd, za pogonske mašine i priključke. Ukupni troškovi se izračunavaju u dve grupe, fiksni i varijabilni troškovi. Fiksni troškovi se sastoje od depresijacije, kamate, poreza, smeštaja i osiguranja, dok varijabilni troškovi uključuju gorivo, mazivo, plate, popravke i održavanje. Razvijeni program uspešno izračunava troškove rada po času rada i po hektaru, za agregate različitih pogonskih i priključnih mašina. Analiza bilansa svakog agregata takođe može da se izvede. Ovaj program može da bude korisno sredstvo za preporuke farmerima pri kupovini mašina, pri određivanju cene iznajmljivanja i sl. Ovo takođe može da pomogne preduzimačima u servisima da odrede cene iznajmljivanja različitih mašina na osnovu analize bilansa

Cell free tumor supernatant leads to CD4⁺ T cell depletion by inducing apoptosis.

<p>A, Purified human peripheral CD4⁺ T cells were cultured in the presence of media alone or cell-free MCF-7-spent media (±theaflavins, doses from 6.25 µg/ml to 50 µg/ml). After 48 hours, viable cell numbers were scored by Trypan Blue exclusion method. B, Graphical representation of percent apoptosis of CD4⁺ T cells (<i>left panel</i>) and Jurkat T cells (<i>right panel</i>). CD4⁺ T cells labelled with Annexin V-PE and 7AAD were analyzed flow cytometrically. Annexin V/7AAD-positive cells were regarded as apoptotic cells. Values are mean±S.E.M. of five independent sets of experiments.</p