Sustained-release protamine sulphate-impregnated microspheres may reduce the frequent administration of recombinant interferon α-2b in ovarian cancer: in-vitro characterization.

Parenteral administration of recombinant interferon-α-2b (rINF-α-2b) at a dose of 50×10 IU once a week for 8 weeks is recommended for ovarian cancer. However, short half-life, small therapeutic index and proteolytic degradation cause fluctuations in plasma level and pose barriers in the development of a clinically viable dosage form. Therefore, in the present investigation, fluorescein isothiocynate-tagged rINF-α-2b was loaded into stearic acid (*rINF-α-2b-SMs), pectin (*rINF-α-2b-PMs) and gelatin (*rINF-α-2b-GMs) microspheres. Parameters such as particle size, ζ potential, encapsulation efficiency and in-vitro release were studied to follow the optimization process. The formulation, *rINF-α-2b-GMs of particle size 8.3±2.1 µm with an encapsulation efficiency of 76.0±7.4%, offered 97.4% of *rINF-α-2b release at 288 h. Thus, negatively charged extended-release formulation *rINF-α-2b-GMs was then tethered with a gradient concentration (5-20 mg/ml) of a cationic arginine-rich protein stabilizer, protamine sulphate (Pt). The nanoformulation, *rINF-α-2b-Pt-GMs-15 superimposed with 15 mg/ml of Pt, released 95.0% of *rINF-α-2b at 336 h and was designated as the optimized formulation. The optimized formulation also conserved the primary and secondary structure of *rINF-α-2b as analysed by gel electrophoresis and circular dichroism. Moreover, in-vitro cytotoxicity analysis of SKOV3 cells of the optimized nanoformulation reported significantly (one-way analysis of variance test, P<0.05) lower IC50 (414.3 IU/ml) compared with *rINF-α-2b-GMs (514.3 IU/ml) and pure rINF-α-2b (628.6 IU/ml) at 72 h by offering a prolonged cytotoxic effect. Therefore, *rINF-α-2b-Pt-GMs-15, a promising nanomedicine, warrants further in-depth in-vivo study to scale up the technology for clinical translation.

Two insulin-like peptide family members from the mosquito Aedes aegypti exhibit differential biological and receptor binding activities.

Insects encode multiple ILPs but only one homolog of the vertebrate IR that activates the insulin-signaling pathway. However, it remains unclear whether all insect ILPs are high affinity ligands for the IR or have similar biological functions. The yellow fever mosquito, Aedes aegypti, encodes eight ILPs with prior studies strongly implicating ILPs from the brain in regulating metabolism and the maturation of eggs following blood feeding. Here we addressed whether two ILP family members expressed in the brain, ILP4 and ILP3, have overlapping functional and receptor binding activities. Our results indicated that ILP3 exhibits strong insulin-like activity by elevating carbohydrate and lipid storage in sugar-fed adult females, whereas ILP4 does not. In contrast, both ILPs exhibited dose-dependent gonadotropic activity in blood-fed females as measured by the stimulation of ovaries to produce ecdysteroids and the uptake of yolk by primary oocytes. Binding studies using ovary membranes indicated that ILP4 and ILP3 do not cross compete; a finding further corroborated by cross-linking and immunoblotting experiments showing that ILP3 binds the MIR while ILP4 binds an unknown 55kDa membrane protein. In contrast, each ILP activated the insulin-signaling pathway in ovaries as measured by enhanced phosphorylation of Akt. RNAi and inhibitor studies further indicated that the gonadotropic activity of ILP4 and ILP3 requires the MIR and a functional insulin-signaling pathway. Taken together, our results indicate that two members of the Ae. aegypti ILP family exhibit partially overlapping biological activity and different binding interactions with the MIR.

An insulin-like peptide regulates egg maturation and metabolism in the mosquito Aedes aegypti.

Ingestion of vertebrate blood is essential for egg maturation and transmission of disease-causing parasites by female mosquitoes. Prior studies with the yellow fever mosquito, Aedes aegypti, indicated blood feeding stimulates egg production by triggering the release of hormones from medial neurosecretory cells in the mosquito brain. The ability of bovine insulin to stimulate a similar response further suggested this trigger is an endogenous insulin-like peptide (ILP). A. aegypti encodes eight predicted ILPs. Here, we report that synthetic ILP3 dose-dependently stimulated yolk uptake by oocytes and ecdysteroid production by the ovaries at lower concentrations than bovine insulin. ILP3 also exhibited metabolic activity by elevating carbohydrate and lipid storage. Binding studies using ovary membranes indicated that ILP3 had an IC(50) value of 5.9 nM that was poorly competed by bovine insulin. Autoradiography and immunoblotting studies suggested that ILP3 binds the mosquito insulin receptor (MIR), whereas loss-of-function experiments showed that ILP3 activity requires MIR expression. Overall, our results identify ILP3 as a critical regulator of egg production by A. aegypti.

Blocking of malaria parasite development in mosquito and fecundity reduction by midgut antibodies in Anopheles stephensi (Diptera: Culicidae).

Rabbits were immunized three times with extracts of Anopheles stephensi midgut. Immunized rabbits showed a high titer of antibodies when characterized by ELISA. We investigated the effect of anti-mosquito midgut antibodies on mosquito fecundity, longevity, mortality, engorgement, and the development of the malaria parasite in mosquitoes. Fecundity was reduced significantly (38%) and similarly hatchability by about 43.5%. There was no statistically significant effect on mortality, longevity, and engorgement. When the mosquito blood meal contained anti-midgut antibodies, fewer oocysts of Plasmodium vivax developed in the mosquito midgut and the proportion of mosquitoes becoming infected was significantly reduced. We also found that the midgut antibodies inhibit the development and/or translocation of the sporozoites. Antisera raised against midgut of A. stephensi recognized eight polypeptides (110, 92, 70, 45, 38, 29, 15, 13 kDa) by Western blotting. Cross-reactive antigens/epitopes present in other tissues of A. stephensi were also examined both by Western blotting and in vivo ELISA. Together, these observations open an avenue for research toward the development of a vector-based malaria parasite transmission blocking vaccine and/or anti-mosquito vaccine.

Alterations in polypeptides pattern in malaria vector Anopheles stephensi, fed upon immunized blood causing fecundity reduction.

Changes in polypeptides pattern of haemolymph, midgut, ovary and salivary glands of female mosquito A. stephensi were studied when fed upon anti-mosquito haemolymph antibodies. The expression of almost all polypeptides was reduced in haemolymph and ovary of the immune fed mosquitoes as compared to control. However, there was no significant difference in case of midgut and salivary glands. Seven polypeptides 100, 90, 84, 80, 62, 19 and 12.5 kDa were absent in haemolymph and five 92, 90, 80, 60 and 55 kDa were absent in ovaries. Changes in the polypeptide pattern have been correlated with the fecundity reduction due to immunized blood feeding.