Comparison of gene therapy strategies for treatment of liver diseases

Abstract   Liver-directed gene therapy can be aimed at replacing a missing gene product, overexpressing or ectopically expressing a gene product in the liver, generating proteins that are normally not produced in the liver (e.g. hormones, vaccines), down-regulating specific gene expression and targeted repair of genetic mutations. A common critical requirement for achieving these goals is the availability of efficient methods for transferring DNA and RNA into target organ in vivo . Both recombinant viruses and non-viral vectors are being explored for transferring nucleic acids to cells in vitro and in vivo . This review compares the characteristics of these vectors in the context of their potential application in liver-directed gene therapy for various inherited or acquired disorders.     

TNF-α, nitric oxide and IFN-γ are all critical for development of necrosis in the small intestine and early mortality in genetically susceptible mice infected perorally with Toxoplasma gondii

We previously reported that genetic susceptibility of mice to peroral infection with T. gondii is associated with CD4+ T cell-dependent, interferon (IFN)-gamma-mediated necrosis of their small intestine. We examined the role of tumour necrosis factor (TNF)-alpha and nitric oxide (NO), in addition to IFN-gamma. At 7 days after infection, a marked increase in CD4+ T cells was observed in lamina propria mononuclear cells (LPC) of the small intestine as compared with normal mice, and significantly greater amounts of mRNA for IFN-gamma, TNF-alpha, and inducible NO synthase (iNOS) were detected in LPC of the small intestine of infected than uninfected animals. Treatment of infected mice with anti-TNF-alpha monoclonal antibody (mAb) or the iNOS inhibitor, aminoguanidine, prevented necrosis and prolonged time to death. Infected iNOS-targeted mutant mice did not develop the disease whereas infected, control mice did. Treatment with anti-TNF-alpha mAb did not affect the expression of IFN-gamma in the LPC but inhibited expression of iNOS in the infected mice, indicating the role of TNF-alpha in the induction of iNOS. These results suggest that NO induced by a combination of IFN-gamma and TNF-alpha through activation of iNOS is a critical mediator of intestinal pathology and contributes to early mortality in genetically susceptible mice.     

Tissue Drug Accumulation and Ultrastructural Changes during Amiodarone Administration in Rats

Pulmonary and hepatotoxicity arc the two major side effectsof chronic amiodarone therapy. We studied the accumulation ofamiodarone and its principal metabolite, desethylamiodarone,in lung and liver of rats treated ip for 21 to 23 days witheither 40 or 80 mg/kg/day amiodarone. The ultrastructural changesin liver, lung, and alveolar macro-phages in saline controlsand in rats on the two amiodarone dosage regimens were investigated.There was a dose-dependent increase in amiodarone and desethylamiodaronelevels in serum and in tissues. The desethylamiodarone/amiodaroneratios in liver and lung, but not in serum, increased significantlywith increasing dose. Serum also contained another metabolite,mono-deiodinated desethylamiodarone. Increase in vacuolizationand presence of whorled lamellar inclusion bodies in alveolarmacrophages occurred with an increase in dose and higher lungamiodarone and desethylamiodarone levels. Electron microscopyof the liver of amiodarone-treated rats revealed the presenceof large inclusion bodies partially filled with amorphous materialin the cytoplasm. The quantitative relationship of the abovechanges to organ toxicity and to phospholipidosis that accompaniesamiodarone administration remains to be established.     

Aetiology and outcome of acute viral hepatitis in pregnancy

The aetiologic types of sporadic acute viral hepatitis in 169 pregnant women were compared with those of 70 non-pregnant women and 287 adult men. The majority of pregnant women (87.6%) came with acute hepatitis in the last trimester of pregnancy. Non-A, non-B (NANB) hepatitis accounted for 81.6% of hepatitis during pregnancy in comparison with 48.6% in non-pregnant women and 57.1% in adult men. Hepatitis A was extremely uncommon during pregnancy. Hepatitis B infection accounted for 17% of all cases in pregnant women compared with 45% in controls. Acute viral hepatitis in pregnancy had a poor outcome as assessed by maternal and/or fetal mortality (28.5%). The outcome was equally bad in hepatitis NANB and hepatitis B. Pregnant women generally had significantly lower immunoglobulin levels in comparison with non-pregnant women. In acute NANB hepatitis during pregnancy, serum IgG and IgM levels were lower and higher, respectively, compared with those in non-pregnant women and pregnant women with acute hepatitis B. It is suggested that an immune suppression during pregnancy might be responsible for increased susceptibility to acute NANB viral hepatitis, which, by itself, seems to induce only a transient acute phase IgM response.