IL-1R1 signaling in TBI: assessing chronic impacts and neuroinflammatory dynamics in a mouse model of mild closed-head injury.

Neuroinflammation contributes to secondary injury cascades following traumatic brain injury (TBI), with alternating waves of inflammation and resolution. Interleukin-1 (IL-1), a critical neuroinflammatory mediator originating from brain endothelial cells, microglia, astrocytes, and peripheral immune cells, is acutely overexpressed after TBI, propagating secondary injury and tissue damage. IL-1 affects blood-brain barrier permeability, immune cell activation, and neural plasticity. Despite the complexity of cytokine signaling post-TBI, we hypothesize that IL-1 signaling specifically regulates neuroinflammatory response components. Using a closed-head injury (CHI) TBI model, we investigated IL-1's role in the neuroinflammatory cascade with a new global knock-out (gKO) mouse model of the IL-1 receptor (IL-1R1), which efficiently eliminates all IL-1 signaling. We found that IL-1R1 gKO attenuated behavioral impairments 14 weeks post-injury and reduced reactive microglia and astrocyte staining in the neocortex, corpus callosum, and hippocampus. We then examined whether IL-1R1 loss altered acute neuroinflammatory dynamics, measuring gene expression changes in the neocortex at 3, 9, 24, and 72 h post-CHI using the NanoString Neuroinflammatory panel. Of 757 analyzed genes, IL-1R1 signaling showed temporal specificity in neuroinflammatory gene regulation, with major effects at 9 h post-CHI. IL-1R1 signaling specifically affected astrocyte-related genes, selectively upregulating chemokines like Ccl2, Ccl3, and Ccl4, while having limited impact on cytokine regulation, such as Tnfα. This study provides further insight into IL-1R1 function in amplifying the neuroinflammatory cascade following CHI in mice and demonstrates that suppression of IL-1R1 signaling offers long-term protective effects on brain health.

PCB126 exposure during pregnancy alters maternal and fetal gene expression.

Polychlorinated biphenyls (PCBs) are organic pollutants that can have lasting impacts on offspring health. Here, we sought to examine maternal and fetal gene expression differences of aryl hydrocarbon receptor (AHR)-regulated genes in a mouse model of prenatal PCB126 exposure. Female mice were bred and gavaged with 1 µmole/kg bodyweight PCB126 or vehicle control on embryonic days 0 and 14, and maternal and fetal tissues were collected on embryonic day 18.5. Total RNAs were isolated, and gene expression levels were analyzed in both maternal and fetal tissues using the NanoString nCounter system. Interestingly, we found that the expression levels of cytochrome P450 (Cyp)1a1 and Cyp1b1 were significantly increased in response to PCB exposure in the tested maternal and fetal tissues. Furthermore, PCB exposure altered the expression of several other genes related to energy balance, oxidative stress, and epigenetic regulation in a manner that was less consistent across tissue types. These results indicate that maternal PCB126 exposure significantly alters gene expression in both developing fetuses and pregnant dams, and such changes vary in intensity and expressivity depending on tissue type. The altered gene expression may provide insights into pathophysiological mechanisms by which in utero PCB exposures contribute to PCB-induced postnatal metabolic diseases.

Reduced sphingolipid biosynthesis modulates proteostasis networks to enhance longevity.

As the elderly population increases, chronic, age-associated diseases are challenging healthcare systems around the world. Nutrient limitation is well known to slow the aging process and improve health. Regrettably, practicing nutrient restriction to improve health is unachievable for most people. Alternatively, pharmacological strategies are being pursued including myriocin which increases lifespan in budding yeast. Myriocin impairs sphingolipid synthesis, resulting in lowered amino acid pools which promote entry into a quiescent, long-lived state. Here we present transcriptomic data during the first 6 hours of drug treatment that improves our mechanistic understanding of the cellular response to myriocin and reveals a new role for ubiquitin in longevity. Previously we found that the methionine transporter Mup1 traffics to the plasma membrane normally in myriocin-treated cells but is not active and undergoes endocytic clearance. We now show that UBI4, a gene encoding stressed-induced ubiquitin, is vital for myriocin-enhanced lifespan. Furthermore, we show that Mup1 fused to a deubiquitinase domain impairs myriocin-enhanced longevity. Broader effects of myriocin treatment on ubiquitination are indicated by our finding of a significant increase in K63-linked ubiquitin polymers following myriocin treatment. Although proteostasis is broadly accepted as a pillar of aging, our finding that ubiquitination of an amino acid transporter promotes longevity in myriocin-treated cells is novel. Addressing the role of ubiquitination/deubiquitination in longevity has the potential to reveal new strategies and targets for promoting healthy aging.

Transection injury differentially alters the proteome of the human sural nerve.

Regeneration after severe peripheral nerve injury is often poor. Knowledge of human nerve regeneration and the growth microenvironment is greatly lacking. We aimed to identify the regenerative proteins in human peripheral nerve by comparing the proteome before and after a transection injury. In a unique study design, we collected closely matched samples of naïve and injured sural nerve. Naïve and injured (two weeks after injury) samples were analyzed using mass spectrometry and immunoassays. We found significantly altered levels following the nerve injury. Mass spectrometry revealed that injury samples had 568 proteins significantly upregulated and 471 significantly downregulated compared to naïve samples (q-value ≤ 0.05 and Z ≥ |2| (log2)). We used Gene Ontology (GO) pathway overrepresentation analysis to highlight groups of proteins that were significantly upregulated or downregulated with injury-induced degeneration and regeneration. Significant protein changes in key pathways were identified including growth factor levels, Schwann cell de-differentiation, myelination downregulation, epithelial-mesenchymal transition (EMT), and axonal regeneration pathways. The proteomes of the uninjured nerve compared to the degenerating/regenerating nerve may reveal biomarkers to aid in the development of repair strategies such as infusing supplemental trophic factors and in monitoring neural tissue regeneration.

Monosomy X in Female Mice Influences the Regional Formation and Augments the Severity of Angiotensin II-Induced Aortopathies.

OBJECTIVE: Turner syndrome women (monosomy X) have high risk of aortopathies consistent with a role for sex chromosomes in disease development. We demonstrated that sex chromosomes influence regional development of Ang II (angiotensin II)-induced aortopathies in mice. In this study, we determined if the number of X chromosomes regulates regional development of Ang II-induced aortopathies. Approach and Results: We used females with varying numbers of X chromosomes (XX female mice [XXF] or XO female mice [XOF]) on an C57BL/6J (ascending aortopathies) or low-density lipoprotein receptor deficient (Ldlr-/-) background (descending and abdominal aortopathies) compared with XY males (XYM). To induce aortopathies, mice were infused with Ang II. XOF (C57BL/6J) exhibited larger percent increases in ascending aortic lumen diameters than Ang II-infused XXF or XYM. Ang II-infused XOF (Ldlr-/-) exhibited similar incidences of thoracic (XOF, 50%; XYM, 71%) and abdominal aortopathies (XOF, 83%; XYM, 71%) as XYM, which were greater than XXF (XXF, 0%). Abdominal aortic lumen diameters and maximal external diameters were similar between XOF and XYM but greater than XXF, and these effects persisted with extended Ang II infusions. Larger aortic lumen diameters, abdominal aortopathy incidence (XXF, 20%; XOF, 75%), and maximal aneurysm diameters (XXF, 1.02±0.17; XOF, 1.96±0.32 mm; P=0.027) persisted in ovariectomized Ang II-infused XOF mice. Data from RNA-seq demonstrated that X chromosome genes that escape X-inactivation (histone lysine demethylases Kdm5c and Kdm6a) exhibited lower mRNA abundance in aortas of XOF than XXF (P=0.033 and 0.024, respectively). Conversely, DNA methylation was higher in aortas of XOF than XXF (P=0.038). CONCLUSIONS: The absence of a second X chromosome promotes diffuse Ang II-induced aortopathies in females.

RNA Sequencing of Human Peripheral Nerve in Response to Injury: Distinctive Analysis of the Nerve Repair Pathways.

The development of regenerative therapies for central nervous system diseases can likely benefit from an understanding of the peripheral nervous system repair process, particularly in identifying potential gene pathways involved in human nerve repair. This study employed RNA sequencing (RNA-seq) technology to analyze the whole transcriptome profile of the human peripheral nerve in response to an injury. The distal sural nerve was exposed, completely transected, and a 1 to 2 cm section of nerve fascicles was collected for RNA-seq from six participants with Parkinson's disease, ranging in age between 53 and 70 yr. Two weeks after the initial injury, another section of the nerve fascicles of the distal and pre-degenerated stump of the nerve was dissected and processed for RNA-seq studies. An initial analysis between the pre-lesion status and the postinjury gene expression revealed 3,641 genes that were significantly differentially expressed. In addition, the results support a clear transdifferentiation process that occurred by the end of the 2-wk postinjury. Gene ontology (GO) and hierarchical clustering were used to identify the major signaling pathways affected by the injury. In contrast to previous nonclinical studies, important changes were observed in molecular pathways related to antiapoptotic signaling, neurotrophic factor processes, cell motility, and immune cell chemotactic signaling. The results of our current study provide new insights regarding the essential interactions of different molecular pathways that drive neuronal repair and axonal regeneration in humans.

Long-Term Intranasal Insulin Aspart: A Profile of Gene Expression, Memory, and Insulin Receptors in Aged F344 Rats.

Intranasal insulin is a safe and effective method for ameliorating memory deficits associated with pathological brain aging. However, the impact of different formulations and the duration of treatment on insulin's efficacy and the cellular processes targeted by the treatment remain unclear. Here, we tested whether intranasal insulin aspart, a short-acting insulin formulation, could alleviate memory decline associated with aging and whether long-term treatment affected regulation of insulin receptors and other potential targets. Outcome variables included measures of spatial learning and memory, autoradiography and immunohistochemistry of the insulin receptor, and hippocampal microarray analyses. Aged Fischer 344 rats receiving long-term (3 months) intranasal insulin did not show significant memory enhancement on the Morris water maze task. Autoradiography results showed that long-term treatment reduced insulin binding in the thalamus but not the hippocampus. Results from hippocampal immunofluorescence revealed age-related decreases in insulin immunoreactivity that were partially offset by intranasal administration. Microarray analyses highlighted numerous insulin-sensitive genes, suggesting insulin aspart was able to enter the brain and alter hippocampal RNA expression patterns including those associated with tumor suppression. Our work provides insights into potential mechanisms of intranasal insulin and insulin resistance, and highlights the importance of treatment duration and the brain regions targeted.

XX sex chromosome complement promotes atherosclerosis in mice.

Men and women differ in circulating lipids and coronary artery disease (CAD). While sex hormones such as estrogens decrease CAD risk, hormone replacement therapy increases risk. Biological sex is determined by sex hormones and chromosomes, but effects of sex chromosomes on circulating lipids and atherosclerosis are unknown. Here, we use mouse models to separate effects of sex chromosomes and hormones on atherosclerosis, circulating lipids and intestinal fat metabolism. We assess atherosclerosis in multiple models and experimental paradigms that distinguish effects of sex chromosomes, and male or female gonads. Pro-atherogenic lipids and atherosclerosis are greater in XX than XY mice, indicating a primary effect of sex chromosomes. Small intestine expression of enzymes involved in lipid absorption and chylomicron assembly are greater in XX male and female mice with higher intestinal lipids. Together, our results show that an XX sex chromosome complement promotes the bioavailability of dietary fat to accelerate atherosclerosis.

Tau drives translational selectivity by interacting with ribosomal proteins.

There is a fundamental gap in understanding the consequences of tau-ribosome interactions. Tau oligomers and filaments hinder protein synthesis in vitro, and they associate strongly with ribosomes in vivo. Here, we investigated the consequences of tau interactions with ribosomes in transgenic mice, in cells, and in human brain tissues to identify tau as a direct modulator of ribosomal selectivity. First, we performed microarrays and nascent proteomics to measure changes in protein synthesis. Using regulatable rTg4510 tau transgenic mice, we determined that tau expression differentially shifts both the transcriptome and the nascent proteome, and that the synthesis of ribosomal proteins is reversibly dependent on tau levels. We further extended these results to human brains and found that tau pathologically interacts with ribosomal protein S6 (rpS6 or S6), a crucial regulator of translation. Consequently, protein synthesis under translational control of rpS6 was reduced under tauopathic conditions in Alzheimer's disease brains. Our data establish tau as a driver of RNA translation selectivity. Moreover, since regulation of protein synthesis is critical for learning and memory, aberrant tau-ribosome interactions in disease could explain the linkage between tauopathies and cognitive impairment.

Aging-Related Calcium Dysregulation in Rat Entorhinal Neurons Homologous with the Human Entorhinal Neurons in which Alzheimer's Disease Neurofibrillary Tangles First Appear.

Aging is the leading risk factor for idiopathic Alzheimer's disease (AD), indicating that normal aging processes promote AD and likely are present in the neurons in which AD pathogenesis originates. In AD, neurofibrillary tangles (NFTs) appear first in entorhinal cortex, implying that aging processes in entorhinal neurons promote NFT pathogenesis. Using electrophysiology and immunohistochemistry, we find pronounced aging-related Ca2 + dysregulation in rat entorhinal neurons homologous with the human neurons in which NFTs originate. Considering that humans recapitulate many aspects of animal brain aging, these results support the hypothesis that aging-related Ca2 + dysregulation occurs in human entorhinal neurons and promotes NFT pathogenesis.

Acute psychosocial stress in mid-aged male rats causes hyperthermia, cognitive decline, and increased deep sleep power, but does not alter deep sleep duration.

Aging is associated with altered sleep architecture and worsened hippocampus-dependent cognition, highly prevalent clinical conditions that detract from quality of life for the elderly. Interestingly, exposure to psychosocial stress causes similar responses in young subjects, suggesting that age itself may act as a stressor. In prior work, we demonstrated that young animals show loss of deep sleep, deficits in cognition, and elevated body temperature after acute stress exposure, whereas aged animals are hyporesponsive on these measures. However, it is unclear if these age-altered stress responses occur in parallel over the course of aging. To address this, here we repeated the experiment in mid-aged animals. We hypothesized that mid-aged stress responses would be intermediate between those of young and aged subjects. Sixteen mid-aged (12 months) male F344 rats were implanted with EEG/EMG emitters to monitor sleep architecture and body temperature, and were trained on the Morris water maze for 3 days. On the fourth day, half of the subjects were restrained for 3 hours immediately before the water maze probe trial. Sleep architecture and body temperature were measured during the ensuing inactive period, and on the following day, endpoint measures were taken. Restrained mid-aged animals showed resistance to deep sleep loss, but demonstrated stress-induced water maze probe trial performance deficits as well as postrestraint hyperthermia. Taken in the context of prior work, these data suggest that age-related loss of sleep architecture stress sensitivity may precede both cognitive and body temperature-related stress insensitivity.

Sex Chromosome Complement Defines Diffuse Versus Focal Angiotensin II-Induced Aortic Pathology.

OBJECTIVE: Aortic pathologies exhibit sexual dimorphism, with aneurysms in both the thoracic and abdominal aorta (ie, abdominal aortic aneurysm [AAA]) exhibiting higher male prevalence. Women have lower prevalence of aneurysms, but when they occur, aneurysms progress rapidly. To define mechanisms for these sex differences, we determined the role of sex chromosome complement and testosterone on the location and progression of angiotensin II (AngII)-induced aortic pathologies. APPROACH AND RESULTS: We used transgenic male mice expressing Sry (sex-determining region Y) on an autosome to create Ldlr (low-density lipoprotein receptor)-deficient male mice with an XY or XX sex chromosome complement. Transcriptional profiling was performed on abdominal aortas from XY or XX males, demonstrating 1746 genes influenced by sex chromosomes or sex hormones. Males (XY or XX) were either sham-operated or orchiectomized before AngII infusions. Diffuse aortic aneurysm pathology developed in XY AngII-infused males, whereas XX males developed focal AAAs. Castration reduced all AngII-induced aortic pathologies in XY and XX males. Thoracic aortas from AngII-infused XY males exhibited adventitial thickening that was not present in XX males. We infused male XY and XX mice with either saline or AngII and quantified mRNA abundance of key genes in both thoracic and abdominal aortas. Regional differences in mRNA abundance existed before AngII infusions, which were differentially influenced by AngII between genotypes. Prolonged AngII infusions resulted in aortic wall thickening of AAAs from XY males, whereas XX males had dilated focal AAAs. CONCLUSIONS: An XY sex chromosome complement mediates diffuse aortic pathology, whereas an XX sex chromosome complement contributes to focal AngII-induced AAAs.

FK506-Binding Protein 12.6/1b, a Negative Regulator of [Ca2+], Rescues Memory and Restores Genomic Regulation in the Hippocampus of Aging Rats.

Hippocampal overexpression of FK506-binding protein 12.6/1b (FKBP1b), a negative regulator of ryanodine receptor Ca2+ release, reverses aging-induced memory impairment and neuronal Ca2+ dysregulation. Here, we tested the hypothesis that FKBP1b also can protect downstream transcriptional networks from aging-induced dysregulation. We gave hippocampal microinjections of FKBP1b-expressing viral vector to male rats at either 13 months of age (long-term, LT) or 19 months of age (short-term, ST) and tested memory performance in the Morris water maze at 21 months of age. Aged rats treated ST or LT with FKBP1b substantially outperformed age-matched vector controls and performed similarly to each other and young controls (YCs). Transcriptional profiling in the same animals identified 2342 genes with hippocampal expression that was upregulated/downregulated in aged controls (ACs) compared with YCs (the aging effect). Of these aging-dependent genes, 876 (37%) also showed altered expression in aged FKBP1b-treated rats compared with ACs, with FKBP1b restoring expression of essentially all such genes (872/876, 99.5%) in the direction opposite the aging effect and closer to levels in YCs. This inverse relationship between the aging and FKBP1b effects suggests that the aging effects arise from FKBP1b deficiency. Functional category analysis revealed that genes downregulated with aging and restored by FKBP1b were associated predominantly with diverse brain structure categories, including cytoskeleton, membrane channels, and extracellular region. Conversely, genes upregulated with aging but not restored by FKBP1b associated primarily with glial-neuroinflammatory, ribosomal, and lysosomal categories. Immunohistochemistry confirmed aging-induced rarefaction and FKBP1b-mediated restoration of neuronal microtubular structure. Therefore, a previously unrecognized genomic network modulating diverse brain structural processes is dysregulated by aging and restored by FKBP1b overexpression.SIGNIFICANCE STATEMENT Previously, we found that hippocampal overexpression of FK506-binding protein 12.6/1b (FKBP1b), a negative regulator of intracellular Ca2+ responses, reverses both aging-related Ca2+ dysregulation and cognitive impairment. Here, we tested whether hippocampal FKBP1b overexpression also counteracts aging changes in gene transcriptional networks. In addition to reducing memory deficits in aged rats, FKBP1b selectively counteracted aging-induced expression changes in 37% of aging-dependent genes, with cytoskeletal and extracellular structure categories highly associated with the FKBP1b-rescued genes. Our results indicate that, in parallel with cognitive processes, a novel transcriptional network coordinating brain structural organization is dysregulated with aging and restored by FKBP1b.

Transcriptional signatures of brain aging and Alzheimer's disease: What are our rodent models telling us?

Aging is the biggest risk factor for idiopathic Alzheimer's disease (AD). Recently, the National Institutes of Health released AD research recommendations that include: appreciating normal brain aging, expanding data-driven research, using open-access resources, and evaluating experimental reproducibility. Transcriptome data sets for aging and AD in humans and animal models are available in NIH-curated, publically accessible databases. However, little work has been done to test for concordance among those molecular signatures. Here, we test the hypothesis that brain transcriptional profiles from animal models recapitulate those observed in the human condition. Raw transcriptional profile data from twenty-nine studies were analyzed to produce p-values and fold changes for young vs. aged or control vs. AD conditions. Concordance across profiles was assessed at three levels: (1) # of significant genes observed vs. # expected by chance; (2) proportion of significant genes showing directional agreement; (3) correlation among studies for magnitude of effect among significant genes. The highest concordance was found within subjects across brain regions. Normal brain aging was concordant across studies, brain regions, and species, despite profound differences in chronological aging among humans, rats and mice. Human studies of idiopathic AD were concordant across brain structures and studies, but were not concordant with the transcriptional profiles of transgenic AD mouse models. Further, the five transgenic AD mouse models that were assessed were not concordant with one another. These results suggest that normal brain aging is similar in humans and research animals, and that different transgenic AD model mice may reflect selected aspects of AD pathology.

Female Mice With an XY Sex Chromosome Complement Develop Severe Angiotensin II-Induced Abdominal Aortic Aneurysms.

BACKGROUND: Abdominal aortic aneurysms (AAAs) are a deadly pathology with strong sexual dimorphism. Similar to humans, female mice exhibit far lower incidences of angiotensin II-induced AAAs than males. In addition to sex hormones, the X and Y sex chromosomes, and their unique complements of genes, may contribute to sexually dimorphic AAA pathology. Here, we defined the effect of female (XX) versus male (XY) sex chromosome complement on angiotensin II-induced AAA formation and rupture in phenotypically female mice. METHODS: Female low-density lipoprotein receptor (Ldlr) deficient mice with an XX or XY sex chromosome complement were infused with angiotensin II for 28 days to induce AAAs. Abdominal aortic lumen diameters were quantified by ultrasound, whereas AAA diameters were quantified at study end point. DNA microarrays were performed on abdominal aortas. To mimic males, female mice were administered a single dose of testosterone as neonates or as adults before angiotensin II infusions. RESULTS: Female Ldlr-/- deficient mice with an XX and XY sex chromosome complement had similar sex organ weights and low serum testosterone concentrations. Abdominal aortas from female XY mice selectively expressed Y chromosome genes, whereas genes known to escape X inactivation were higher in XX females. The majority of aortic gene differences in XY versus XX females fell within inflammatory pathways. AAA incidences doubled and aneurysms ruptured in XY females. AAAs from XY females exhibited inflammation, and plasma interleukin-1ß concentrations were increased in XY females. Moreover, aortas from XY females had augmented matrix metalloproteinase activity and increased oxidative stress. Last, testosterone exposure applied chronically, or as a single bolus at postnatal day 1, markedly worsened AAA outcomes in XY in comparison with XX adult females. CONCLUSIONS: An XY sex chromosome complement in phenotypic females profoundly influenced aortic gene expression profiles and promoted AAA severity. When XY females were exposed to testosterone, aneurysm rupture rates were striking. Mechanisms for augmented AAA severity in XY females include increased inflammation, augmented matrix metalloproteineases, and oxidative stress. Our results demonstrate that genes on the sex chromosomes regulate aortic vascular biology and contribute to sexual dimorphism of AAAs. Sex chromosome genes may serve as novel targets for sex-specific AAA therapeutics.

Intranasal Insulin Improves Age-Related Cognitive Deficits and Reverses Electrophysiological Correlates of Brain Aging.

Peripheral insulin resistance is a key component of metabolic syndrome associated with obesity, dyslipidemia, hypertension, and type 2 diabetes. While the impact of insulin resistance is well recognized in the periphery, it is also becoming apparent in the brain. Recent studies suggest that insulin resistance may be a factor in brain aging and Alzheimer's disease (AD) whereby intranasal insulin therapy, which delivers insulin to the brain, improves cognition and memory in AD patients. Here, we tested a clinically relevant delivery method to determine the impact of two forms of insulin, short-acting insulin lispro (Humalog) or long-acting insulin detemir (Levemir), on cognitive functions in aged F344 rats. We also explored insulin effects on the Ca(2+)-dependent hippocampal afterhyperpolarization (AHP), a well-characterized neurophysiological marker of aging which is increased in the aged, memory impaired animal. Low-dose intranasal insulin improved memory recall in aged animals such that their performance was similar to that seen in younger animals. Further, because ex vivo insulin also reduced the AHP, our results suggest that the AHP may be a novel cellular target of insulin in the brain, and improved cognitive performance following intranasal insulin therapy may be the result of insulin actions on the AHP.

Tunable somatosensory stimulation for selective sleep restriction studies in rodents.

Many methods for sleep restriction in rodents have emerged, but most are intrusive, lack fine control, and induce stress. Therefore, a versatile, non-intrusive means of sleep restriction that can alter sleep in a controlled manner could be of great value in sleep research. In previous work, we proposed a novel system for closed-loop somatosensory stimulation based on mechanical vibration and applied it to the task of restricting Rapid Eye Movement (REM) sleep in mice [1]. While this system was effective, it was a crude prototype and did not allow precise control over the amplitude and frequency of stimulation applied to the animal. This paper details the progression of this system from a binary, "all-or-none" version to one that allows dynamic control over perturbation to accomplish graded, state-dependent sleep restriction. Its preliminary use is described in two applications: deep sleep restriction in rats, and REM sleep restriction in mice.

The Challenges of Interstitial Cystitis: Current Status and Future Prospects.

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a syndrome of unpleasant bladder sensations and lower urinary tract symptoms. The three main proposed etiologies are bladder urothelial dysfunction, bladder inflammation (possible neurogenic), and neuropathic pain. Despite decades of basic and clinical research, IC/BPS remains difficult to treat. A variety of treatments are used, each aimed towards one etiology. For example, glycosaminoglycans are thought to improve the urothelial permeability barrier, anti-inflammatory agents are used to decrease general inflammation, and mast cell stabilizers and/or antagonists of mast cell products are used in the treatment of neurogenic inflammation. In the (unfortunately frequent) event that a treatment fails, possible reasons are that (1) the clinician is aiming towards the wrong etiology for that patient (i.e., the treatment is off target) or (2) the correct etiology is being targeted, but the treatment is not ameliorating it (i.e., the treatment is sub-therapeutic). This is a crucial distinction, because an off-target treatment should be abandoned, but a sub-therapeutic treatment should be escalated. Currently, our inability to make this crucial distinction is the greatest obstacle to effective treatment. An important future advance would be to identify urine or serum biomarkers specific to each etiologic target. Then, each biomarker could be used to select appropriate patients for each treatment and monitor the treatment's effect on its intended target.

Reversal of Aging-Related Neuronal Ca2+ Dysregulation and Cognitive Impairment by Delivery of a Transgene Encoding FK506-Binding Protein 12.6/1b to the Hippocampus.

Brain Ca2+ regulatory processes are altered during aging, disrupting neuronal, and cognitive functions. In hippocampal pyramidal neurons, the Ca2+ -dependent slow afterhyperpolarization (sAHP) exhibits an increase with aging, which correlates with memory impairment. The increased sAHP results from elevated L-type Ca2+ channel activity and ryanodine receptor (RyR)-mediated Ca2+ release, but underlying molecular mechanisms are poorly understood. Previously, we found that expression of the gene encoding FK506-binding protein 12.6/1b (FKBP1b), a small immunophilin that stabilizes RyR-mediated Ca2+ release in cardiomyocytes, declines in hippocampus of aged rats and Alzheimer's disease subjects. Additionally, knockdown/disruption of hippocampal FKBP1b in young rats augments neuronal Ca2+ responses. Here, we test the hypothesis that declining FKBP1b underlies aging-related hippocampal Ca2+ dysregulation. Using microinjection of adeno-associated viral vector bearing a transgene encoding FKBP1b into the hippocampus of aged male rats, we assessed the critical prediction that overexpressing FKBP1b should reverse Ca2+ -mediated manifestations of brain aging. Immunohistochemistry and qRT-PCR confirmed hippocampal FKBP1b overexpression 4-6 weeks after injection. Compared to aged vector controls, aged rats overexpressing FKBP1b showed dramatic enhancement of spatial memory, which correlated with marked reduction of sAHP magnitude. Furthermore, simultaneous electrophysiological recording and Ca2+ imaging in hippocampal neurons revealed that the sAHP reduction was associated with a decrease in parallel RyR-mediated Ca2+ transients. Thus, hippocampal FKBP1b overexpression reversed key aspects of Ca2+ dysregulation and cognitive impairment in aging rats, supporting the novel hypothesis that declining FKBP1b is a molecular mechanism underlying aging-related Ca2+ dysregulation and unhealthy brain aging and pointing to FKBP1b as a potential therapeutic target. SIGNIFICANCE STATEMENT: This paper reports critical tests of a novel hypothesis that proposes a molecular mechanism of unhealthy brain aging and possibly, Alzheimer's disease. For more than 30 years, evidence has been accumulating that brain aging is associated with dysregulation of calcium in neurons. Recently, we found that FK506-binding protein 12.6/1b (FKBP1b), a small protein that regulates calcium, declines with aging in the hippocampus, a brain region important for memory. Here we used gene therapy approaches and found that raising FKBP1b reversed calcium dysregulation and memory impairment in aging rats, allowing them to perform a memory task as well as young rats. These studies identify a potential molecular mechanism of brain aging and may also have implications for treatment of Alzheimer's disease.