Lowe syndrome patient cells display mTOR- and RhoGTPase-dependent phenotypes alleviated by rapamycin and statins.

Lowe syndrome (LS) is an X-linked developmental disease characterized by cognitive deficiencies, bilateral congenital cataracts and renal dysfunction. Unfortunately, this disease leads to the early death of affected children often due to kidney failure. Although this condition was first described in the early 1950s and the affected gene (OCRL1) was identified in the early 1990s, its pathophysiological mechanism is not fully understood and there is no LS-specific cure available to patients. Here we report two important signaling pathways affected in LS patient cells. While RhoGTPase signaling abnormalities led to adhesion and spreading defects as compared to normal controls, PI3K/mTOR hyperactivation interfered with primary cilia assembly (scenario also observed in other ciliopathies with compromised kidney function). Importantly, we identified two FDA-approved drugs able to ameliorate these phenotypes. Specifically, statins mitigated adhesion and spreading abnormalities while rapamycin facilitated ciliogenesis in LS patient cells. However, no single drug was able to alleviate both phenotypes. Based on these and other observations, we speculate that Ocrl1 has dual, independent functions supporting proper RhoGTPase and PI3K/mTOR signaling. Therefore, this study suggest that Ocrl1-deficiency leads to signaling defects likely to require combinatorial drug treatment to suppress patient phenotypes and symptoms.

Cerebro- and renoprotective activities through platelet-derived biomaterials against cerebrorenal syndrome in rat model.

Though the cross-induction of either acute kidney (AKI) injury to ischemic stroke (IS) or IS to AKI might not be encountered in the early stages of cerebrorenal syndrome (CRS), both pathologies coexist in late stages. Therefore, we firstly established a late stage CRS rat model by simultaneous induction of both diseases, and further, cerebro and reno-protective activities of human platelet-rich plasma (hPRP), a blood-derived tissue engineering biomaterial, were tested in this pathology. hPRP was administrated via left common carotid artery and abdominal aorta 2 h post-sham procedure in Sprague-Dawley rats. Circulatory inflammatory markers (TNF-α/MPO/IL-6/Ly6G/CD11b/c), histopathologic cerebro and renal changes and oxidative stress were determined. Inflammation, infarct size, brain-associated inflammatory/DNA and mitochondrial damage and oxidative-stress with reduced neurons and neurological function were manifested in CRS group compared to other groups. CRS group also demonstrated declined renal function, accelerated renal collagen deposition, fibrosis and compromised glomerular podocyte components (podocin/ZO-1/fibronectin/synaptopodin). However, hPRP simultaneously suppressed all the inflammatory, cerebral and renal pathologic characteristics. hPRP also inhibited the expression of brain-associated inflammatory/DNA/mitochondrial damage and oxidative-stress biomarkers. These findings imply that hPRP may effectively exert cerebro- and renoprotective activities in late stage CRS through anti-oxidative, anti-inflammatory, anti-DNA and anti-mitochochondrial damaging activities.

Amelioration of hypophosphatemic rickets and osteoporosis with pamidronate and growth hormone in Lowe syndrome.

The oculocerebrorenal syndrome of Lowe, an X-linked multisystem disorder, was diagnosed in a male patient who presented with typical abnormalities of the eyes, kidneys and nervous system. Besides congenital cataracts, renal tubular dysfunction and psychomotor retardation, the patient had also suffered from profound failure to thrive, growth hormone deficiency, severe osteoporosis with hypophosphatemic rickets, and progressive renal dysfunction since early childhood, which were attributed to the metabolic derangements following Fanconi syndrome. Direct sequencing of the OCRL1 gene (responsible for the oculocerebrorenal syndrome of Lowe) revealed a de novo c.2282_2283insT in exon 20, which resulted in premature termination of translation (D762X). After monthly intravenous administration of pamidronate since the age of 17.8 years, his urine creatinine clearance and tubular resorption of phosphate increased slightly and bone mineral density was much improved (Z score increased from -7.3 to -3.3) without deterioration of renal function. Simultaneous growth hormone therapy enhanced the positive response. The beneficial osseous and renal effects of the bisphosphonate, along with growth hormone treatment in Lowe syndrome with hypophosphatemia, may be related to reduced renal calcium and phosphate excretion.

Oculocerebrorenal Lowe syndrome: a literature review and two case reports.

The present paper reviews the dental findings in oculocerebrorenal Lowe syndrome and presents two case histories. Reports of different patients are useful in order to enhance knowledge about the syndrome, because there are so many different oral manifestations.

Oral carnitine therapy in children with cystinosis and renal Fanconi syndrome.

11 children with either cystinosis or Lowe's syndrome had a reduced content of plasma and muscle carnitine due to renal Fanconi syndrome. After treatment with oral L-carnitine, 100 mg/kg per d divided every 6 h, plasma carnitine concentrations became normal in all subjects within 2 d. Initial plasma free fatty acid concentrations, inversely related to free carnitine concentrations, were reduced after 7-20 mo of carnitine therapy. Muscle lipid accumulation, which varied directly with duration of carnitine deficiency (r = 0.73), improved significantly in three of seven rebiopsied patients after carnitine therapy. One Lowe's syndrome patient achieved a normal muscle carnitine level after therapy. Muscle carnitine levels remained low in all cystinosis patients, even though cystinotic muscle cells in culture took up L-[3H]carnitine normally. The half-life of plasma carnitine for cystinotic children given a single oral dose approximated 6.3 h; 14% of ingested L-carnitine was excreted within 24 h. Studies in a uremic patient with cystinosis showed that her plasma carnitine was in equilibrium with some larger compartment and may have been maintained by release of carnitine from the muscle during dialysis. Because oral L-carnitine corrects plasma carnitine deficiency, lowers plasma free fatty acid concentrations, and reverses muscle lipid accumulation in some patients, its use as therapy in renal Fanconi syndrome should be considered. However, its efficacy in restoring muscle carnitine to normal, and the optimal dosage regimen, have yet to be determined.