The Use of Antifibrotic Recombinant nAG Protein in a Rat Liver Fibrosis Model.

OBJECTIVES: The "nAG" protein is the key protein mediating the regeneration of amputated limbs in salamanders. The senior author (MMA) developed the original hypothesis that since "nAG" is a "regenerative" protein, it must be also an "antifibrotic' protein. The antifibrotic properties were later confirmed in a rabbit skin hypertrophic scar model as well as in a rat spinal cord injury model. The aim of this study is to evaluate the potential therapeutic properties of the nAG protein in a rat liver fibrosis model. METHODOLOGY: Liver fibrosis was induced using intraperitoneal injections of carbon tetrachloride (CCL4). A total of 45 rats were divided equally into 3 groups: Group I (the control group) received normal saline injections for 8 weeks, Group II received CCL4 for 8 weeks, and Group III received CCL4 and nAG for 8 weeks. At the end of the experiment, the serum levels of 6 proteins (hyaluronic acid, PDGF-AB, TIMP-1, laminin, procollagen III N-terminal peptide, and collagen IV-alpha 1 chain) were measured. Liver biopsies were also taken and the stages of live fibrosis were assessed histologically. RESULTS: The CCL4 treatment resulted in a significant increase in the serum levels of all 6 measured proteins. The nAG treatment significantly reduced these high levels. The degree of liver fibrosis was also significantly reduced in the CCL4/nAG group compared to the CCL4 group. CONCLUSIONS: nAG treatment was able to significantly reduce the serum levels of several protein markers of liver fibrosis and also significantly reduced the histological degree of liver fibrosis.

The Use of Recombinant nAG Protein in Spinal Cord Crush Injury in a Rat Model.

OBJECTIVE: To evaluate the therapeutic properties of nAG protein during the recovery following acute spinal cord injuries in the rat. STUDY DESIGN: An experimental study. PLACE AND DURATION OF STUDY: King Saud University, Riyadh, Saudi Arabia, from September 2014 to September 2015. METHODOLOGY: Eight rats were studied (4 control rats and 4 experimental rats; and hence 50% were controls and 50% were experimental). All rats were subjected to an acute spinal cord injury using the aneurysmal clip injury model. Immediately after the injury, a single intra-dural injection of either normal saline (in the control group) or the nAG protein (in the experimental group) was done. Assessment of both groups was done over a 6-week period with regard to weight maintenance, motor recovery scores, MRI and histopathology of the injury site. RESULTS: Weight maintenance was seen in the experimental and not in the control rats. Starting at 3 weeks after injury, the motor recovery was significantly (p<0.05) better in the experimental group. MRI assessment at 6 weeks showed better maintenance of cord continuity and less fluid accumulation at the injury site in the nAG-treated group. Just proximal to the injury site, there was less gliosis in the experimental group compared to the control group. At the crush injury site, there was less tissue architecture distortion, less vacuole formation, and less granulation tissue formation in the experimental group. CONCLUSION: The local injection nAG protein enhances neuro-restoration, reduces gliosis, and reduces vacuole/ granulation tissue formation following acute spinal cord crush injury in the rat aneurysmal clip animal model.

Salamander-derived, human-optimized nAG protein suppresses collagen synthesis and increases collagen degradation in primary human fibroblasts.

Unlike humans, salamanders regrow their amputated limbs. Regeneration depends on the presence of regenerating axons which upregulate the expression of newt anterior gradient (nAG) protein. We had the hypothesis that nAG might have an inhibitory effect on collagen production since excessive collagen production results in scarring, which is a major enemy to regeneration. nAG gene was designed, synthesized, and cloned. The cloned vector was then transfected into primary human fibroblasts. The results showed that the expression of nAG protein in primary human fibroblast cells suppresses the expression of collagen I and III, with or without TGF- ß 1 stimulation. This suppression is due to a dual effect of nAG both by decreasing collagen synthesis and by increasing collagen degradation. Furthermore, nAG had an inhibitory effect on proliferation of transfected fibroblasts. It was concluded that nAG suppresses collagen through multiple effects.