Bispecific antibodies targeting tumor-associated antigens and neutralizing complement regulators increase the efficacy of antibody-based immunotherapy in mice.

The efficacy of antibody-based immunotherapy is due to the activation of apoptosis, the engagement of antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity (CDC). We developed a novel strategy to enhance CDC using bispecific antibodies (bsAbs) that neutralize the C-regulators CD55 and CD59 to enhance C-mediated functions. Two bsAbs (MB20/55 and MB20/59) were designed to recognize CD20 on one side. The other side neutralizes CD55 or CD59. Analysis of CDC revealed that bsAbs could kill 4-25 times more cells than anti-CD20 recombinant antibody in cell lines or cells isolated from patients with chronic lymphocytic leukemia. The pharmacokinetics of the bsAbs was evaluated in a human-SCID model of Burkitt lymphoma. The distribution profile of bsAbs mimics the data obtained by studying the pharmacokinetics of anti-CD20 antibodies, showing a peak in the tumor mass 3-4 days after injection. The treatment with bsAbs completely prevented the development of human/SCID lymphoma. The tumor growth was blocked by the activation of the C cascade and by the recruitment of macrophages, polymorphonuclear and natural killer cells. This strategy can easily be applied to the other anti-tumor C-fixing antibodies currently used in the clinic or tested in preclinical studies using the same vector with the appropriate modifications.

NIR-labeled nanoparticles engineered for brain targeting: in vivo optical imaging application and fluorescent microscopy evidences.

The presence of the blood-brain barrier (BBB) makes extremely difficult to develop efficacious strategies for targeting contrast agents and delivering drugs inside the Central Nervous System (CNS). To overcome this drawback, several kinds of CNS-targeted nanoparticles (NPs) have been developed. In particular, we proposed poly-lactide-co-glycolide (PLGA) NPs engineered with a simil-opioid glycopeptide (g7), which have already proved to be a promising tool for achieving a successful brain targeting after i.v. administration in rats. In order to obtain CNS-targeted NPs to use for in vivo imaging, we synthesized and administrated in mice PLGA NPs with double coverage: near-infrared (NIR) probe (DY-675) and g7. The optical imaging clearly showed a brain localization of these novel NPs. Thus, a novel kind of NIR-labeled NPs were obtained, providing a new, in vivo detectable nanotechnology tool. Besides, the confocal and fluorescence microscopy evidences allowed to further confirm the ability of g7 to promote not only the rat, but also the mouse BBB crossing.

Two novel cosegregating mutations in tRNAMet and COX III, in a patient with exercise intolerance and autoimmune polyendocrinopathy.

We report a 12-year-old patient with growth retardation, exercise intolerance, lactic acidosis (increasing after exercise) and autoimmune polyendocrinopathy type 2. Muscle biopsy shows abundant COX-negative fibers, subsarcolemmal mitochondrial aggregates and markedly reduced activities of all respiratory chain complexes. Genetic analysis identified two new cosegregating mutations in Met-tRNA (m.4415A>G) and Cox III (m.9922A>C), located in highly conserved regions of MtDNA. Both the mutations are heteroplasmics in multiple patients' tissues. Single-muscle fiber analysis showed significantly higher levels of both the mutations in COX-negative than in normal fibers. In addition, a possible link between the mitochondrial dysfunction and the autoimmune disease is suggested.

Two novel POLG mutations causing hepatic mitochondrial DNA depletion with recurrent hypoketotic hypoglycaemia and fatal liver dysfunction.

BACKGROUND: Inherited mtDNA depletion syndromes (MDS) are a group of severe mitochondrial disorders resulting from defects in nucleus-encoded factors and often associated with severe or fatal liver failure. PATIENT: In this article, we describe the case of an 18-month-old patient with recurrent hypoketotic hypoglycaemia and fatal hepatic dysfunction with liver mtDNA depletion. METHODS: The assessment of mtDNA copy number was performed on leucocytes, liver and muscle biopsy by Quantitative Real Time PCR and total RNA from liver biopsy was used as a template to amplify the cDNA of the POLG1 gene. RESULTS: Sequence analysis identified two previously undescribed mutations (1868T>G and 2263A>G) located in the gene coding the catalytic subunit of mitochondrial DNA polymerase gamma (POLG), predicting an L623W and K755E amino acid change, respectively. Both mutations were located in the highly conserved linker region of the protein and were absent in more than 200 healthy unrelated control subjects. The identification of these two mutations allowed us to perform genetic counselling and prenatal diagnosis. CONCLUSION: Our data further expand the spectrum of POLG1 gene mutations and the unique phenotype reported (late onset isolated liver disease without lactic acidosis) increase the variability of clinical presentations associated with mutations in this gene.