Faculty Bibliography

Therapeutic hypothermia favorably impacts neurologic outcomes in patients after cardiopulmonary arrest, although the appropriate target temperature is less clear. Its safety profile in patients with systemic sclerosis (SSc) and Raynaud phenomenon (RP), who may be at increased risk for ischemic complications, has not been addressed in the literature, to our knowledge. Digital lesions are commonly seen in patients with SSc, and cold-induced myocardial ischemia has also been reported. We describe a case of a man with SSc, RP, and digital ulcers who underwent therapeutic hypothermia after cardiopulmonary arrest. He regained full neurologic function, and except for digital necrosis, no hypothermia-associated adverse events were observed. Other risk factors for ischemia, such as cocaine use, may have contributed to the development of the digital necrosis. However, clinicians should be aware of the risk for ischemic complications in patients with SSc and RP when considering the appropriate target temperature after cardiopulmonary arrest.

Cell-based delivery of cell penetrating peptides (CPPs) could represent a new platform for intracellular peptide delivery to local tissues. Expressed CPPs, coupled to a secretory signal peptide (SP), can support intercellular transport. However, low secretion efficiency, which may correlate with the positive charge of most CPPs, has emerged as one of the main impediments for efficient intercellular transport. We have reported that a modified Tat-based CPP (Tatm) with reduced positive charge is secreted efficiently, but its transduction activity was greatly reduced. We now show that a triple repeat of Tatm (Tatm3x) with an elongated alpha-helical amphipathic structure enhances transduction activity and simultaneously retains its secretion efficacy, although passage through the secretory pathway reduces its cell-penetrating activity. SP-Tatm3x supports intercellular transport of fused fluorescent proteins, as well as cell entry and function of a pro-apoptotic peptide. In addition, SP-Tatm3x largely escapes RNA inhibition, which is identified as another potential impediment to CPP-mediated intercellular transport. Expression of SP-Tatm3x in heparan sulfate proteoglycan-negative cells further improves its transduction activity. These results demonstrate the feasibility of intercellular transport of proteins, but further work is needed to better understand the reduction of cell-penetrating activity associated with secretion of CPP-fusion proteins.

Despite advances in vector technology, inefficient gene transfer still limits clinical efficacy of cancer gene therapy. Cell-penetrating peptides (CPPs), such as the basic domain of the transactivator of transcription (Tat) protein of HIV-1, are internalized by intact cells and have been used to deliver purified recombinant proteins. A combination of gene therapy with protein transduction technology could induce a strong bystander effect and represent a platform to deliver proteins to target cells. However, whether expressed CPP can facilitate intercellular trafficking, i.e., a bystander effect, is controversial. Our data suggest that expressed fusion proteins that contain the basic domain of Tat do not induce a detectable bystander effect. However, Tat-fusion proteins that also contain a secretory signal peptide (SP) can induce a bystander effect in vitro, although the in vivo effect is small. Surprisingly, despite the presence of a SP, the bystander effect does not seem to be related to secretion of the fusion protein. In fact, Tat-fusion proteins are secreted very inefficiently, and protein transduction seems largely mediated by fusion proteins that are released by cell lysis. Modification of Tat can improve secretion efficacy and prevent cleavage by the endoprotease furin, but passage through the secretory pathway is associated with reduced transduction activity of Tat-fusion proteins

Cell penetrating peptides (CPPs) are widely used to deliver proteins and other macromolecules into cells. Generally, CPPs are either synthesized and coupled to the therapeutic payload or expressed in bacteria as fusion proteins followed by various purification steps. However, despite great interest in this technology, difficulties with production, purification and unfavorable pharmacokinetics are still limiting its clinical success. As an alternative approach, expression of CPPs that support intercellular transfer of fused proteins could avoid production and purification needs and serve as a tool to deliver therapeutic proteins. We have previously reported that the basic domain of HIV Tat, fused to fluorescent proteins can support intercellular transfer, but only when coupled to a secretory signal peptide (SP). However, SP-Tat fusion proteins are very inefficiently secreted and transduction seems mostly mediated by fusion proteins released by means other than secretion through the classic pathway. We also demonstrated that a modified Tat-based CPP (Tatm) is secreted much more efficiently, but its transduction activity was greatly reduced compared to Tat. We now show that an elongated 3x repeat sequence of Tatm (Tatm3x) enhances transduction activity. Secretion activity is greatly improved compared to Tat, although somewhat reduced when compared to Tatm. Expressed SP-Tatm3x fusion proteins are localized in the ER and cytoplasm and are secreted mainly via the classical pathway. Fusion proteins that are released through cell lysis have greatly improved transduction activity compared to SP-Tatm. Based on co-culture and mixing experiments, expressed SP-Tatm3x supports intercellular transport of fused fluorescent proteins in vitro. As previously shown for SP-Tatm fusion proteins, travel through the secretory pathway also reduces transduction activity of SP-Tatm3x fusion proteins. In conclusion, expressed SP-Tatm3x displays improved secretion and transduction activity and represents an important step forward in the development of a CPP that supports intercellular transport of fused proteins

OBJECTIVE: To evaluate the effect of angiopoietin-1, an angiogenic growth factor, on lung capillary leakage and survival in a murine model of acute lung injury. DESIGN: Laboratory investigation. SETTING: Research laboratory at New York University School of Medicine and Department of Veterans Affairs, NY Harbor Healthcare System. SUBJECTS: C57BL/6 mice weighing 18-20 g, susceptible to endotoxin-induced acute lung injury. INTERVENTIONS: Acute lung injury was induced in C57BL/6 mice by the intraperitoneal administration of endotoxin. The effects of angiopoietin-1, expressed from a nonreplicating E1a-deleted adenovirus containing the angiopoietin-1 complementary DNA (AdAng1), on survival and lung injury were evaluated. An E1a-deleted adenovirus that does not contain a transgene (Ad312) and phosphate-buffered saline were used as controls. MEASUREMENTS AND MAIN RESULTS: Angiopoietin-1 protein was detected by immunoblotting in the serum of mice that received an intraperitoneal injection of AdAng1 but not in mice that received the control virus Ad312. When compared with control groups, mice that received AdAng1 5 days before endotoxin administration had improved survival and significantly less protein leakage from the circulation into the lungs, as detected by quantitative spectrophotometric measurements of Evans blue dye. Furthermore, when compared with controls, histopathology and immunostaining of lungs against CD31 and smooth muscle actin suggested preservation of vascular integrity and decreased tissue damage in mice pretreated with AdAng1. When endotoxin administration preceded infection with AdAng1 by 3 hrs, no benefit was observed. CONCLUSIONS: These data show that adenoviral mediated expression of angiopoietin-1 can protect against the development of lung capillary protein leak and decrease the mortality induced by endotoxin. However, the timing of AdAng1 administration in relation to the onset of lung injury may be critical