Tissue accumulation kinetics of ciclesonide-active metabolite and budesonide in mice.

Inhaled corticosteroids (ICS) are mainstay treatment of asthma and chronic obstructive pulmonary disease. However, highly lipophilic ICS accumulate in systemic tissues, which may lead to adverse systemic effects. The accumulation of a new, highly lipophilic ICS, ciclesonide and its active metabolite (des-CIC) has not yet been reported. Here, we have compared tissue accumulation of des-CIC and an ICS of a moderate lipophilicity, budesonide (BUD), after 14 days of once-daily treatment in mice. Single, three or 14 daily doses of [(3) H]-des-CIC or [(3) H]-BUD were administered subcutaneously to male CD1 albino mice, which were killed at 4 hr, 24 hr or 5 days after the last dose. Distribution of tissue concentration of radioactivity was studied by quantitative whole-body autoradiography. Pattern of radioactivity distribution across most tissues was similar for both corticosteroids after a single as well as after repeated dosing. However, tissue concentration of radioactivity differed between des-CIC and BUD. After a single dose, concentrations of radioactivity for both corticosteroids were low for most tissues but increased over 14 days of daily dosing. The tissue radioactivity of des-CIC at 24 hr and 5 days after the 14th dose was 2-3 times higher than that of BUD in majority of tissues. Tissue accumulation, assessed as concentration of tissue radioactivity 5 days after the 14th versus 3rd dose, showed an average ratio of 5.2 for des-CIC and 2.7 for BUD (p < 0.0001). In conclusion, des-CIC accumulated significantly more than BUD. Systemic accumulation may lead to increased risk of adverse systemic side effects during long-term therapy.

Whole-body autoradiography reveals that the Peptostreptococcus magnus immunoglobulin-binding domains of protein L preferentially target B lymphocytes in the spleen and lymph nodes in vivo.

Protein L is an immunoglobulin (Ig)-binding protein produced by the Gram-positive bacterium Peptostreptococcus magnus that interacts with the variable region of Ig kappa light chains. The Ig light chain-binding capacity of protein L gives it the potential to interact with cells expressing surface Ig such as B cells. The present study was performed to address the in vivo trafficking of protein L at both the organ and the cellular level. Using the powerful technique of whole-body autoradiography in a murine model system, we demonstrate specific targeting of protein L to secondary lymphoid tissues in whole-animal analysis. The observed targeting depends on the capacity to interact with murine Ig, as tissue targeting was not apparent in mice given protein H, an Ig-binding protein produced by Streptococcus pyogenes with affinity for human but not murine Ig. Tissue targeting data were combined with flow cytometry analysis, which demonstrated the capacity of protein L to target and activate B lymphocytes in vivo. B cells targeted by protein L had increased surface expression of CD86 and MHC-II, and protein L was present in vacuolar compartments of B cells. Protein L did not bind T cells or natural killer cells but had some capacity to target dendritic cells and macrophages. The data show that protein L preferentially targets secondary lymphoid organs, and activates and is internalized by B cells in vivo. Furthermore, the observed tissue and cell targeting properties require an affinity for murine Ig. These data support the potential use of this Ig-binding protein as a targeting approach to deliver agents to defined cell populations in vivo.

Camptothecin poly[n-(2-hydroxypropyl) methacrylamide] copolymers in antitopoisomerase-I tumor therapy: intratumor release and antitumor efficacy.

Soluble copolymers of camptothecin (CPT), based on poly[N-(2-hydroxypropyl) methacrylamide] (pHPMA), were obtained by conjugation through the degradable spacers -Gly-Phe-Leu-Gly- or -Gly-6-aminohexanoyl-Gly-. We investigated to what extent passive accumulation and retention of hydroxypropyl methacrylamide copolymer of CPT (pHPMA-CPT) in tumors and modulation of the drug release influence efficacy. Release of CPT in vivo was detected by time-resolved phase-shift fluorescence imaging on tumor specimens, based on the evidence that free and bound drug had different fluorescence lifetimes in solution. HT-29 murine specimens, obtained at several times after treatment with (3)H-labeled free CPT, pHPMA-Gly-Phe-Leu-Gly-CPT, or pHPMA-Gly-6-aminohexanoyl-Gly-CPT, were either imaged for time-resolved phase-shift fluorescence or subjected to autoradiography. Phase shifts of CPT conjugates were equal or longer than those of free CPT, indicating the presence of both free and polymer-bound drug in the tumor, in agreement with autoradiograms. pHPMA-Gly-Phe-Leu-Gly-CPT underwent relevant intratumor hydrolysis during the first 24 h, whereas the hydrolysis of pHPMA-Gly-6-aminohexanoyl-Gly-CPT was slow. The latter showed antitumor activity at doses from 10 to 22.5 mg/kg/day against s.c. HT-29, A2780, M14, and A549 s.c. xenografts. Moreover, inhibition of tumor growth lasted for up to 73-88 days, and cures were observed on mice with orthotopic implanted HT-29; pHPMA-Gly-Phe-Leu-Gly-CPT was 2-fold more potent than pHPMA-Gly-6-aminohexanoyl-Gly-CPT but less tolerated. Our data suggest that the efficacy of pHPMA-CPT copolymers is related to their intratumor accumulation, and in vivo properties of releasing CPT by esterolytic and proteolytic degradation.