Failed Induction of Heme Oxygenase 1 in Endothelial Cells Exposed to the Hemoglobin Based Oxygen Carrier Oxyglobin®

Fatty Liver/Adipose Tissue Dual-Targeting Nanoparticles with Heme Oxygenase-1 Inducer for Amelioration of Obesity, Obesity-Induced Type 2 Diabetes, and Steatohepatitis

Persistent uptake of high-calorie diets induces the storage of excessive lipid in visceral adipose tissue. Lipids secreted from obese adipose tissue are accumulated in peripheral tissues such as the liver, pancreas, and muscle, and impair insulin sensitivity causing type 2 diabetes mellitus (T2DM). Furthermore, the accumulation of inflammatory cytokines and lipids in the liver induces apoptosis and fibrogenesis, and ultimately causes nonalcoholic steatohepatitis (NASH). To modulate obese tissue environments, it is challenged to selectively deliver inducers of heme oxygenase-1 (HO-1) to adipose tissue with the aid of a prohibitin targeting drug delivery system. Prohibitin binding peptide (PBP), an oligopeptide targeting prohibitin rich in adipose tissue, is conjugated on the surface of Hemin- or CoPP-loaded poly(lactide-co-glycolide) nanoparticles (PBP-NPs). PBP-NPs efficiently differentiate lipid storing white adipocytes into energy-generating brown adipocytes in T2DM and NASH models. In addition, PBP-NPs are found to target prohibitin overexpressed fatty liver in the NASH model and inhibit hepatic uptake of circulating lipids. Furthermore, PBP-NPs switch phenotypes of inflammatory macrophages in damaged organs and lower inflammation. Taken together, dual-targeted induction of HO-1 in fatty adipose and liver tissues is proven to be a promising therapeutic strategy to ameliorate obesity, insulin resistance, and steatohepatitis by lowering lipids and cytokines.

Biological evaluation of liposome-encapsulated hemoglobin surface-modified with a novel PEGylated nonphospholipid amphiphile

Traumatic injury is often associated with hemorrhagic shock. Liposome-encapsulated hemoglobin (LEH) is being developed as an artificial oxygen carrier to address post-hemorrhage oxygen and volume deficit. Here, we report a new composition of LEH based on the use of polyethylene glycol (PEG2K ) conjugated with nonphospholipid hexadecylcarbamoylmethylhexadecanoate (HDAS) to modify the surface of LEH particles. LEH was manufactured by the high-pressure homogenization method using dipalmitoylphosphatidylcholine (∼38 mol%), cholesterol (∼38 mol%), HDAS (∼20 mol%), and highly purified stroma-free human hemoglobin. HDAS-PEG2K was postinserted into the resultant LEH to generate HDAS-PEG2K -LEH. We investigated the potential immune response to HDAS-PEG2K -LEH in a mice model. At the same time, the preparation was tested in a rat model to study the effect of repeated HDAS-PEG2K -LEH injection over 4 weeks. We found that HDAS-PEG2K modification substantially reduced the circulating levels of anaphylatoxins C3a and C5a, as well as plasma levels of thromboxane B2, in mice. Repeated injections of HDAS-PEG2K -LEH in rats did not appear to alter its clearance profile after 4 weeks of treatment. No antibody response against human hemoglobin or PEG was detected in rat plasma. Histological observations of lung, liver, spleen, and kidney were not significantly different between saline-treated rats and HDAS-PEG2K -LEH-treated rats. Immunohistochemical staining for rat heme oxygenase-1 (HO-1) did not show induced expression of HO-1 in these organs. These results suggest that the new surface modification of LEH is immune-neutral and does not adversely affect histology even after repeated administration.

Heme oxygenase-1 expression and its significance for acute rejection following kidney transplantation in rats

OBJECTIVE

To analyze rejection and antiapoptotic effects of heme oxygenase-1 (HO-1) in kidney transplantations, to investigate the protective effects of endogenous HO-1 induced by hemin on acute rat kidney allograft rejection.

METHODS

We selected 27 Brown-Norway rats and 27 male Lewis rats as donors and recipients, respectively, randomly dividing them into three groups: kidney transplantation alone, hemin treatment group, and cyclosporine (CsA) group (n = 18). Six recipient rats were harvested on the first, fifth, or seventh days after operation among each group to examine histopathologic changes in renal tissue, HO-1 protein expression, and acute rejection as well as to measure serum creatinine values.

RESULTS

HO-1 expression in both the kidney transplantation model group and the hemin-induced groups were higher compared with the CsA group (P < .05-.01). The expression increased with the aggravation of rejection; the expression in the CsA group also increased after transplantation but was obviously lower than that of the hemin-induced group (P < .01). The rejection process was relatively mild as indenset by histopathologic examination. The serum creatinine levels among the hemin-induced group were lower compared to the kidney transplantation control group (P < .05), but higher compared to the CsA group (P < .05).

CONCLUSION

HO-1 provided protection of allografts against rejection in rats, but such effects were poorer than those achieved using potent immunosuppressive agents like CsA.