Anti-Neuron-Derived Neurotrophic Factor Antibodies in Secondary Membranous Nephropathy Caused by Syphilis: A Case Report.

We present the case of a 61-year-old man who developed nephrotic syndrome as a result of syphilis-associated secondary membranous nephropathy (MN). The patient showed nephrotic syndrome remission following antibiotic treatment for syphilis alone. Pathologically, the target antigen of immune complexes accumulated on glomerular basement membranes (GBM) in secondary MN caused by syphilis has been reported to be neuron-derived neurotrophic factor (NDNF). His renal histopathology was consistent with secondary MN caused by syphilis, with a full-house pattern on immunofluorescence microscopy, in addition to NDNF deposits that colocalized with IgG deposits granularly on the GBM. However, to date, there is no serological evidence for the involvement of NDNF in the GBM. In the present study, we found that anti-NDNF autoantibodies in the acute-phase serum disappeared in the convalescent-phase serum of a patient who recovered from syphilis and nephrotic syndrome after antibiotic therapy alone. This result supports the hypothesis that treatment of syphilis with antibiotics suppresses NDNF's antigenicity. In summary, we found new serological evidence emphasizing that NDNF is an etiological antigen in secondary MN caused by syphilis.

Intrathecal delivery of AAV-NDNF ameliorates disease progression of ALS mice.

Amyotrophic lateral sclerosis (ALS) is a uniformly lethal neurodegenerative disease characterized by progressive deterioration of motor neurons and neuromuscular denervation. Adeno-associated virus (AAV)-mediated delivery of trophic factors is being considered as a potential disease-modifying therapeutic avenue. Here we show a marked effect of AAV-mediated over-expression of neuron-derived neurotrophic factor (NDNF) on SOD1G93A ALS model mice. First, we adopt AAV-PHP.eB capsid to enable widespread expression of target proteins in the brain and spinal cord when delivered intrathecally. Then we tested the effects of AAV-NDNF on SOD1G93A mice at different stages of disease. Interestingly, AAV-NDNF markedly improved motor performance and alleviated weight loss when delivered at early post-symptomatic stage. Injection in the middle post-symptomatic stages still improved the locomotion ability, although it did not alleviate the loss of body weight. Injection in the late stage also extended the life span of SOD1G93A mice. Furthermore, NDNF expression promoted the survival of spinal motoneurons, reduced abnormal protein aggregation, and preserved the innervated neuromuscular functions. We further analyzed the signaling pathways of NDNF expression and found that it activates cell survival and growth-associated mammalian target of rapamycin signaling pathway and downregulates apoptosis-related pathways. Thus, intrathecally AAV-NDNF delivery has provided a potential strategy for the treatment of ALS.

Neuron-derived neurotrophic factor functions as a novel modulator that enhances endothelial cell function and revascularization processes.

Strategies to stimulate revascularization are valuable for cardiovascular diseases. Here we identify neuron-derived neurotrophic factor (NDNF)/epidermacan as a secreted molecule that is up-regulated in endothelial cells in ischemic limbs of mice. NDNF was secreted from cultured human endothelial cells, and its secretion was stimulated by hypoxia. NDNF promoted endothelial cell network formation and survival in vitro through activation of Akt/endothelial NOS (eNOS) signaling involving integrin αvß3. Conversely, siRNA-mediated knockdown of NDNF in endothelial cells led to reduction of cellular responses and basal Akt signaling. Intramuscular overexpression of NDNF led to enhanced blood flow recovery and capillary density in ischemic limbs of mice, which was accompanied by enhanced phosphorylation of Akt and eNOS. The stimulatory actions of NDNF on perfusion recovery in ischemic muscles of mice were abolished by eNOS deficiency or NOS inhibition. Furthermore, siRNA-mediated reduction of NDNF in muscles of mice resulted in reduction of perfusion recovery and phosphorylation of Akt and eNOS in response to ischemia. Our data indicate that NDNF acts as an endogenous modulator that promotes endothelial cell function and ischemia-induced revascularization through eNOS-dependent mechanisms. Thus, NDNF can represent a therapeutic target for the manipulation of ischemic vascular disorders.

A combinatory genetic strategy for targeting neurogliaform neurons in the mouse basolateral amygdala.

The mouse basolateral amygdala (BLA) contains various GABAergic interneuron subpopulations, which have distinctive roles in the neuronal microcircuit controlling numerous behavioral functions. In mice, roughly 15% of the BLA GABAergic interneurons express neuropeptide Y (NPY), a reasonably characteristic marker for neurogliaform cells (NGFCs) in cortical-like brain structures. However, genetically labeled putative NPY-expressing interneurons in the BLA yield a mixture of interneuron subtypes besides NGFCs. Thus, selective molecular markers are lacking for genetically accessing NGFCs in the BLA. Here, we validated the NGFC-specific labeling with a molecular marker, neuron-derived neurotrophic factor (NDNF), in the mouse BLA, as such specificity has been demonstrated in the neocortex and hippocampus. We characterized genetically defined NDNF-expressing (NDNF+) GABAergic interneurons in the mouse BLA by combining the Ndnf-IRES2-dgCre-D transgenic mouse line with viral labeling, immunohistochemical staining, and in vitro electrophysiology. We found that BLA NDNF+ GABAergic cells mainly expressed NGFC neurochemical markers NPY and reelin (Reln) and exhibited small round soma and dense axonal arborization. Whole-cell patch clamp recordings indicated that most NDNF+ interneurons showed late spiking and moderate firing adaptation. Moreover, ∼81% of BLA NDNF+ cells generated retroaxonal action potential after current injections or optogenetic stimulations, frequently developing into persistent barrage firing. Optogenetic activation of the BLA NDNF+ cell population yielded both GABAA- and GABAB receptor-mediated currents onto BLA pyramidal neurons (PNs). We demonstrate a combinatory strategy combining the NDNF-cre mouse line with viral transfection to specifically target adult mouse BLA NGFCs and further explore their functional and behavioral roles.

Aged Human Multipotent Mesenchymal Stromal Cells Can Be Rejuvenated by Neuron-Derived Neurotrophic Factor and Improve Heart Function After Injury.

Reduced regenerative capacity of aged stem cells hampers the benefits of autologous cell therapy for cardiac regeneration. This study investigated whether neuron-derived neurotrophic factor (NDNF) could rejuvenate aged human bone marrow (hBM)- multipotent mesenchymal stromal cells (MSCs) and whether the rejuvenated hBM-MSCs could improve cardiac repair after ischemic injury. Over-expression of NDNF in old hBM-MSCs decreased cell senescence and apoptosis. Engraftment of NDNF over-expressing old hBM-MSCs into the ischemic area of mouse hearts resulted in improved cardiac function after myocardial infarction, while promoting implanted stem cell survival. Our findings suggest NDNF could be a new factor to rejuvenate aged stem cells and improve their capability to repair the aged heart after injury.

Neudesin as a unique secreted protein with multi-functional roles in neural functions, energy metabolism, and tumorigenesis.

Neudesin was originally identified as a secreted protein with neurotrophic activity, and, thereafter, was also termed neuron-derived neurotrophic factor (NENF) or the candidate oncogene GIG47. Neudesin with a conserved cytochrome 5-like heme/steroid-binding domain activates intracellular signaling pathways possibly through the activation of G protein-coupled receptors. In the brain, hypothalamic Neudesin decreases food intake. Neudesin knockout (KO) mice also exhibit anxiety-like behavior, indicating its roles in the hippocampal anxiety circuitry. Neudesin is also expressed in various peripheral tissues. Neudesin KO mice are strongly resistant to high-fat diet (HFD)-induced obesity due to elevated systemic sympathetic activity, heat production, and adipocytic lipolysis. Neudesin, which is over-expressed or induced by DNA hypomethylation in multiple human cancers, also stimulates tumorigenesis. These findings indicate that Neudesin plays roles in neural functions, energy metabolism, and tumorigenesis and is expected to be a novel target for obesity and anti-cancer treatments.