Inhibiting PNP for the therapy of hyperuricemia in Lesch-Nyhan disease: Preliminary in vitro studies with analogues of immucillin-G

Lesch-Nyhan disease (LND) is a rare X-linked genetic disorder, with complete hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency, uric acid (UA), hypoxanthine and xanthine accumulation, and a devastating neurologic syndrome. UA excess, causing renal failure, is commonly decreased by xanthine oxidoreductase (XOR) inhibitors, such as allopurinol, yielding a xanthine and hypoxanthine increase. Xanthine accumulation may result in renal stones, while hypoxanthine excess seems involved in the neurological disorder. Inhibition of purine nucleoside phosphorylase (PNP) represents a different strategy for lowering urate. PNP catalyzes the cleavage of purine ribo- and d-ribo-nucleosides into ribose/deoxyribose phosphate and free bases, starting catabolism to uric acid. Clinical trials demonstrated that PNP inhibitors, initially developed as anticancer drugs, lowered UA in some gouty patients, in association or not with allopurinol. The present study tested the reliability of an analogue of immucillin-G (C1a), a PNP inhibitor, as a therapy for urate, hypoxanthine, and xanthine excess in LND patients by blocking hypoxanthine production upstream. The therapeutic aim is to limit the administration of XOR inhibitors to LND patients by supplying the PNP inhibitor in low doses, avoiding d-nucleoside toxicity. We report studies conducted in primary cultures of skin fibroblasts from controls and LND patients grown in the presence of the PNP inhibitor. Cell viability, oxypurine release in culture medium, and endocellular nucleotide pattern have been monitored in different growth conditions (inhibitor concentration, time, added inosine). Our results demonstrate effective PNP inhibition by low inhibitor concentration, with reduced hypoxanthine release, and no appreciable toxicity in control or patient cells, suggesting a new therapeutic strategy for LND hyperuricemia.

Primary fibroblasts cultures reveal TDP-43 abnormalities in amyotrophic lateral sclerosis patients with and without SOD1 mutations

TAR DNA-binding protein 43 (TDP-43) is a major component of the pathologic inclusions observed in the motor neurons of amyotrophic lateral sclerosis (ALS) patients. We examined TDP-43 expression in primary fibroblasts cultures from 22 ALS patients, including cases with SOD1 (n = 4), TARDBP (n = 4), FUS (n = 2), and C9ORF72 (n = 3) mutations and 9 patients without genetic defect. By using a phosphorylation-independent antibody, 15 patients showed notable alterations of TDP-43 level in the nuclear or cytoplasmic compartments. In particular, a marked accumulation of TDP-43 was observed in the cytoplasm of all cases with C9ORF72 and TARDBP mutations, 1 patient with FUS mutation and 3 patients without genetic defect. Patients with SOD1 mutations revealed a significant reduction of TDP-43 in the nuclei without cytoplasmic mislocalization. These changes were associated with the presence of truncated and phosphorylated TDP-43 species. Our results show that fibroblasts recapitulate some of hallmark TDP-43 abnormalities observed in neuronal cells. The reduction of full-length TDP-43 level in mutant SOD1 cells indicates that at least some SOD1 mutations alter TDP-43 metabolism.

Seed oil of Joannesia princeps improves cutaneous wound closure in experimental mice

Joannesia princeps (Cotieira) is a well known medicinal plant in Brazil, however, the therapeutic effects of oil obtained from its seeds have still not been demonstrated. The beneficial effects of J. princeps seed oil on cutaneous wound healing on the back of experimental mice were investigated. An excisional lesion in male Swiss mice (n=20 per group) was topically treated with mineral oil or J. princeps seed oil once a day beginning on the day of lesion until the third day after wounding. Animals were killed and lesions collected after 14 days. Murine skin fibroblast cultures were treated with J. princeps seed oil and fibroblast activity was evaluated. In the in vivo assay, J. princeps seed oil increased wound contraction and migratory tongue length, but reduced neutrophil and macrophage number when compared with the control group. Blood vessel number, collagen deposition, and VEGF levels were increased in treated lesions when compared with control lesions. However, J. princeps seed oil reduced myofibroblast density and carbonyl protein levels when compared with the control group. In the in vitro assay, treatment with J. princeps seed oil increased fibroblast migration and proliferation, but reduced myofibroblastic differentiation in vitro. In conclusion, J. princeps seed oil accelerates wound closure increasing angiogenesis, keratinocyte migration, and fibroblast activity while reducing inflammatory response and oxidative damage.

Characteristics of human infant primary fibroblast cultures from Achilles tendons removed post-mortem

Primary cell cultures were investigated as a tool for molecular diagnostics in a forensic setting. Fibroblast cultures had been established from human Achilles tendon resected at autopsies, from cases of sudden infant death syndrome and control infants who died in traumatic events (n=41). After isolation of primary cultures cells were stored at -135°C, and re-established up to 15 years later for experimental intervention. Growth characteristics in cultures were evaluated in relation to the age of the donor, the post mortem interval before sampling, and the storage interval of cells before entry into the study. High interpersonal variation in growth rates and cell doubling time was seen, but no statistically significant differences were found with increasing age of the donor (mean 19 weeks), length of post-mortem interval prior to sampling (6-100 h), or increase in years of storage. Fibroblast cultures established from post-mortem tissue are renewable sources of biological material; they can be the foundation for genetic, metabolic and other functional studies and thus constitute a valuable tool for molecular and pathophysiological investigations in biomedical and forensic sciences.

Increased susceptibility to apoptosis in cultured fibroblasts from antipsychotic-naïve first-episode schizophrenia patients

Altered apoptosis has been proposed as a potential mechanism involved in the abnormal neurodevelopment and neurodegenerative processes associated with schizophrenia. The aim of this study was to investigate in primary fibroblast cultures whether antipsychotic-naïve patients with first-episode schizophrenia have greater apoptotic susceptibility than healthy controls. Cell growth, cell viability and various apoptotic hallmarks (caspase-3 activity, translocation of phosphatidylserine, chromatin condensation and gene expression of AKT1, BAX, BCL2, CASP3, GSK3B and P53) were measured in fibroblast cultures obtained from skin biopsies of patients (n = 11) and healthy controls (n = 8), both in basal conditions and after inducing apoptosis with staurosporine. Compared to controls, cultured fibroblasts from patients showed higher caspase-3 activity and lower BCL2 expression. When exposed to staurosporine, fibroblasts from patients also showed higher caspase-3 activity; a higher percentage of cells with translocated phosphatidylserine and condensed chromatin; and higher p53 expression compared to fibroblasts from controls. No differences in cell viability or cell growth were detected. These results strongly support the hypothesis that first-episode schizophrenia patients may have increased susceptibility to apoptosis, which may be involved in the onset and progression of the disease.

Heat stress and sudden infant death syndrome--stress gene expression after exposure to moderate heat stress

The aim of the present study was to investigate stress gene expression in cultured primary fibroblasts established from Achilles tendons collected during autopsies from sudden infant death syndrome (SIDS) cases, and age-matched controls (infants dying in a traumatic event). Expression of 4 stress responsive genes, HSPA1B, HSPD1, HMOX1, and SOD2, was studied by quantitative reverse transcriptase PCR analysis of RNA purified from cells cultured under standard or various thermal stress conditions. The expression of all 4 genes was highly influenced by thermal stress in both SIDS and control cells. High interpersonal variance found in the SIDS group indicated that they represented a more heterogeneous group than controls. The SIDS group responded to thermal stress with a higher expression of the HSPA1B and HSPD1 genes compared to the control group, whereas no significant difference was observed in the expression of SOD2 and HMOX1 between the two groups. The differences were related to the heat shock treatment as none of the genes were expressed significantly different in SIDS at base levels at 37 °C. SOD2 and HMOX1 were up regulated in both groups, for SOD2 though the expression was lower in SIDS at all time points measured, and may be less related to heat stress. Being found dead in the prone position (a known risk factor for SIDS) was related to a lower HSPA1B up-regulation in SIDS compared to SIDS found on their side or back. The study demonstrates the potential usefulness of gene expression studies using cultured fibroblasts established from deceased individuals as a tool for molecular and pathological investigations in forensic and biomedical sciences.