Conjugated bile acids are nutritionally re-programmable antihypertensive metabolites

BACKGROUND

Hypertension is the largest risk factor affecting global mortality. Despite available medications, uncontrolled hypertension is on the rise, whereby there is an urgent need to develop novel and sustainable therapeutics. Because gut microbiota is now recognized as an important entity in blood pressure regulation, one such new avenue is to target the gut-liver axis wherein metabolites are transacted via host-microbiota interactions. Knowledge on which metabolites within the gut-liver axis regulate blood pressure is largely unknown.

METHOD

To address this, we analyzed bile acid profiles of human, hypertensive and germ-free rat models and report that conjugated bile acids are inversely correlated with blood pressure in humans and rats.

RESULTS

Notably intervening with taurine or tauro-cholic acid rescued bile acid conjugation and reduced blood pressure in hypertensive rats. Subsequently, untargeted metabolomics uncovered altered energy metabolism following conjugation of bile acids as a mechanism alleviating high blood pressure.

CONCLUSION

Together this work reveals conjugated bile acids as nutritionally re-programmable anti-hypertensive metabolites.

Identification of a Gut Commensal That Compromises the Blood Pressure-Lowering Effect of Ester Angiotensin-Converting Enzyme Inhibitors

Background:

Despite the availability of various classes of antihypertensive medications, a large proportion of hypertensive individuals remain resistant to treatments. The reason for what contributes to low efficacy of antihypertensive medications in these individuals is elusive. The knowledge that gut microbiota is involved in pathophysiology of hypertension and drug metabolism led us to hypothesize that gut microbiota catabolize antihypertensive medications and compromised their blood pressure (BP)-lowering effects.

Methods and Results:

To test this hypothesis, we examined the BP responses to a representative ACE (angiotensin-converting enzyme) inhibitor quinapril in spontaneously hypertensive rats (SHR) with or without antibiotics. BP-lowering effect of quinapril was more pronounced in the SHR+antibiotics, indicating that gut microbiota of SHR lowered the antihypertensive effect of quinapril. Depletion of gut microbiota in the SHR+antibiotics was associated with decreased gut microbial catabolism of quinapril as well as significant reduction in the bacterial genus Coprococcus. C. comes, an anaerobic species of Coprococcus, harbored esterase activity and catabolized the ester quinapril in vitro. Co-administration of quinapril with C. comes reduced the antihypertensive effect of quinapril in the SHR. Importantly, C. comes selectively reduced the antihypertensive effects of ester ramipril but not nonester lisinopril.

Conclusions:

Our study revealed a previously unrecognized mechanism by which human commensal C. comes catabolizes ester ACE inhibitors in the gut and lowers its antihypertensive effect.

Deep oncopanel sequencing reveals within block position-dependent quality degradation in FFPE processed samples

Background

Clinical laboratories routinely use formalin-fixed paraffin-embedded (FFPE) tissue or cell block cytology samples in oncology panel sequencing to identify mutations that can predict patient response to targeted therapy. To understand the technical error due to FFPE processing, a robustly characterized diploid cell line was used to create FFPE samples with four different pre-tissue processing formalin fixation times. A total of 96 FFPE sections were then distributed to different laboratories for targeted sequencing analysis by four oncopanels, and variants resulting from technical error were identified.

Results

Tissue sections that fail more frequently show low cellularity, lower than recommended library preparation DNA input, or target sequencing depth. Importantly, sections from block surfaces are more likely to show FFPE-specific errors, akin to “edge effects” seen in histology, while the inner samples display no quality degradation related to fixation time.

Conclusions

To assure reliable results, we recommend avoiding the block surface portion and restricting mutation detection to genomic regions of high confidence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13059-022-02709-8.

Beyond the Gastrointestinal Tract: Oral and Sex-Specific Skin Microbiota Are Associated with Hypertension in Rats with Genetic Disparities

Current knowledge of the link between microbiota and hypertension is limited to the gut. Besides the gut, oral cavity and skin are other locations where sodium chloride (NaCl) is in direct contact with microbiota. While oral nitrate reducing-bacteria generate nitric oxide, which lead to vasodilation and lowering of blood pressure (BP), the skin excretes sodium via sweat glands and is an important site for sodium and BP homeostasis. However, knowledge on the contributions of oral and skin microbiota to BP regulation, is limited. Therefore, the current study was conducted to compare the tripartite relationship between site, sex, and genetic effects on the composition of oral, skin and gut microbiota impacting hypertension. Microbiota were profiled from the oral cavity, skin and feces of both male and female hypertensive Dahl salt-sensitive (S) and congenic rats with genomic substitutions on rat chromosomes (RNO) 1, 5, 9 and 10, demonstrating disparate BP effects. Sex-specific differences in β-diversity were observed only in skin microbiota. The most abundant taxa of the oral and skin microbiota were Actinobacteria and Cyanobacteria, respectively. Oral Actinobacteria were inversely associated with BP. While the abundance of oral Actinobacteria was upregulated by the BP locus on RNO10 in both sexes, depletion of skin Cyanobacteria decreased the protection from hypertension in the RNO5 female, but not male, congenic strain. In conclusion, this is the first study to identify specific microbiota in sites other than gut as contributors to BP regulation. Notably, both oral Actinobacteria and skin Cyanobacteria were beneficial for lowering BP.

Gut Microbiota of Wild Fish as Reporters of Compromised Aquatic Environments Sleuthed through Machine Learning

Human-generated negative impacts on aquatic environments are rising. Despite wild fish playing a key role in aquatic ecologies and comprising a major global food source, physiological consequences of these impacts to them are poorly understood. Here we address the issue through the lens of interrelationship between wild fish and their gut microbiota, hypothesizing that fish microbiota are reporters of the aquatic environs. Two geographically separate teleost wild-fish species were studied (Lake Erie, Ohio and Caribbean Sea, US Virgin Islands). At each geo-location, fresh fecal samples were collected from fish in areas of presence or absence of known aquatic compromise. Gut microbiota was assessed via microbial 16S-rRNA gene sequencing and represents the first complete report for both fish species. Despite marked differences in geography, climate, water type, fish species, habitat, diet and gut microbial compositions, the pattern of shifts in microbiota shared by both fish species was nearly identical due to aquatic compromise. Next, these data were subjected to Machine Learning (ML) to examine reliability for using the fish-gut microbiota as an eco-marker for anthropogenic aquatic impacts. Independent of geo-location, ML predicted aquatic compromise with remarkable accuracy (>90%). Overall, this study represents the first multi-species stress-related comparison of its kind and demonstrates the potential of artificial intelligence via ML as a tool for bio-monitoring and detecting compromised aquatic conditions.

Reconstitution of the host holobiont in germ-free born male rats acutely increases bone growth and affects marrow cellular content

Integration of microbiota in a host begins at birth and progresses during adolescence, forming a multidirectional system of physiological interactions. Here, we present an instantaneous effect of natural, bacterial gut colonization on the acceleration of longitudinal and radial bone growth in germ-free born, 7-wk-old male rats. Changes in bone mass and structure were analyzed after 10 days following the onset of colonization through cohousing with conventional rats and revealed unprecedented acceleration of bone accrual in cortical and trabecular compartments, increased bone tissue mineral density, improved proliferation and hypertrophy of growth plate chondrocytes, bone lengthening, and preferential deposition of periosteal bone in the tibia diaphysis. In addition, the number of small in size adipocytes increased, whereas the number of megakaryocytes decreased, in the bone marrow of conventionalized germ-free rats indicating that not only bone mass but also bone marrow environment is under control of gut microbiota signaling. The changes in bone status paralleled with a positive shift in microbiota composition toward short-chain fatty acids (SCFA)-producing microbes and a considerable increase in cecal SCFA concentrations, specifically butyrate. Furthermore, reconstitution of the host holobiont increased hepatic expression of IGF-1 and its circulating levels. Elevated serum levels of 25-hydroxy vitamin D and alkaline phosphatase pointed toward an active process of bone formation. The acute stimulatory effect on bone growth occurred independently of body mass increase. Overall, the presented model of conventionalized germ-free rats could be used to study microbiota-based therapeutics for combatting dysbiosis-related bone disorders.

Abstract MP38: Identification Of A Gut Microbe That Attenuates The Blood Pressure Lowering Effect Of ACEi Quinapril

Introduction: Treatment resistant hypertension (rHTN) is present in ~20% of all hypertensive patients. rHTN is critical in African American patients who experience early onset, severe outcomes, and weak responsiveness to angiotensin converting enzyme inhibitor (ACEi). The mechanism for drug resistance is unknown. Gut microbiota harbors biotransformative enzymes such as esterase, which may hydrolyze ACEis, reducing absorption. Our study was to identify microbe responsible for ACEi resistance.

Methods: 16-week-old male Spontaneously Hypertensive Rats (SHR) were gavaged with (N=12) or without (N=6) Vancomycin, Meropenem, and Omeprazole (VMO) 50 mg/kg/day for five days to deplete the gut microbiota. A single 8mg/kg dose of quinapril was given to SHR and SHR+VMO before blood pressure (BP) recording via telemetry. Quinapril catabolism was quantified by liquid chromatography-mass spectrometry. Bacterial esterase activity was monitored by hydrolysis of p-nitro-phenylbutyrate. Cecal microbiota was analyzed by 16S rDNA. Fecal microbiota were analyzed by metagenomics in 29 (16 black, 13 white) HTN patients.

Results: Quinapril lowered BP more in the SHR+VMO than SHR ( P <0.0001). With a 50% reduction in bacterial 16S copy numbers ( P <0.0001), the SHR+VMO group showed (1) reduced Coprococcus ( P <0.0001); (2) lower esterase activity per gram of cecal microbiota to hydrolyze quinapril ( P =0.0065); (3) a 50% lower reduction in quinapril quantity (nmol) after incubation with 1mg of cecal lysate for 3 hr ( P <0.0001); (4) decreased bacterial genes in KEGG drug metabolism pathway ( P <0.0001). The abundance of Coprococcus positively correlated with genes in drug metabolism ( P <0.0001). Importantly, co-administration of quinapril with C. comes, a species in Coprococcus genus, reduced the BP-lowering effects of quinapril in the SHR ( P <0.0001). Comparison of human microbiota demonstrated a higher abundance of C. comes in the black hypertensives (poor ACEi responder) than the white (ACEi responder) ( P =0.0167).

Conclusion: We, for the first time, demonstrate a previously unrecognized role of gut microbes in reducing ACEi effectiveness. This serves a foundation for expanding clinical management of antihypertensive drug resistance via manipulation of gut microbiota.

Sexual dimorphism in the progression of type 2 diabetic kidney disease in T2DN rats

Diabetic kidney disease (DKD) is a common complication of diabetes, which frequently leads to end-stage renal failure and increases cardiovascular disease risk. Hyperglycemia promotes renal pathologies such as glomerulosclerosis, tubular hypertrophy, microalbuminuria, and a decline in glomerular filtration rate. Importantly, recent clinical data have demonstrated distinct sexual dimorphism in the pathogenesis of DKD in people with diabetes, which impacts both severity- and age-related risk factors. This study aimed to define sexual dimorphism and renal function in a nonobese type 2 diabetes model with the spontaneous development of advanced diabetic nephropathy (T2DN rats). T2DN rats at 12- and over 48-wk old were used to define disease progression and kidney injury development. We found impaired glucose tolerance and glomerular hyperfiltration in T2DN rats to compare with nondiabetic Wistar control. The T2DN rat displays a significant sexual dimorphism in insulin resistance, plasma cholesterol, renal and glomerular injury, urinary nephrin shedding, and albumin handling. Our results indicate that both male and female T2DN rats developed nonobese type 2 DKD phenotype, where the females had significant protection from the development of severe forms of DKD. Our findings provide further evidence for the T2DN rat strain's effectiveness for studying the multiple facets of DKD.

Microbiota Introduced to Germ-Free Rats Restores Vascular Contractility and Blood Pressure

Commensal gut microbiota are strongly correlated with host hemodynamic homeostasis but only broadly associated with cardiovascular health. This includes a general correspondence of quantitative and qualitative shifts in intestinal microbial communities found in hypertensive rat models and human patients. However, the mechanisms by which gut microbes contribute to the function of organs important for blood pressure (BP) control remain unanswered. To examine the direct effects of microbiota on BP, we conventionalized germ-free (GF) rats with specific pathogen-free rats for a short-term period of 10 days, which served as a model system to observe the dynamic responses when reconstituting the holobiome. The absence of microbiota in GF rats resulted with relative hypotension compared with their conventionalized counterparts, suggesting an obligatory role of microbiota in BP homeostasis. Hypotension observed in GF rats was accompanied by a marked reduction in vascular contractility. Both BP and vascular contractility were restored by the introduction of microbiota to GF rats, indicating that microbiota could impact BP through a vascular-dependent mechanism. This is further supported by the decrease in actin polymerization in arteries from GF rats. Improved vascular contractility in conventionalized GF rats, as indicated through stabilized actin filaments, was associated with an increase in cofilin phosphorylation. These data indicate that the vascular system senses the presence (or lack of) microbiota to maintain vascular tone via actin polymerization. Overall, these results constitute a fundamental discovery of the essential nature of microbiota in BP regulation.

Abstract P112: Elevated Blood Pressure In Conventionalized Germ-free Rats Is Coupled With Upregulation Of Kynurenic Pathway Metabolites And Central Immune Responses

Background: Recent evidence supports that metabolic dysfunction underlies hypertension. Injection of kynurenate, a metabolite of tryptophan pathway, into the paraventricular nucleus of the hypothalamus (PVN) lowers blood pressure (BP). Intestinal absorption and metabolism of tryptophan are impacted by gut microbiota. Since gut-brain axis contributes to gut dysbiosis-inducd hypertension, we hypothesized that gut microbiota modulates the levels of kynurenic pathway metabolites that have central impact on BP regulation.

Methods: We, for the first time, used 7 weeks old male Germ-free (GF) Spague Dawley (SD) rats (n=5) and GF rats co-housed with conventional SD rats for 10 days (GFC) (n=6). BP was measured by tail-cuff. Serum metabolites were quantified by 6495 triple quandrople mass spectrometryand data was normalized using isotoplic labelled compounds. The nucleus of the solitary tract (NTS), the principal sensory nucleus for peripheral changes, and the PVN, a relay center projecting sympathetic output based on the integrated afferent inputs from brain regions including NTS, were analyzed by microarray hybridization for mRNA expression.

Results: Compared to the GF rats, GFC rats had significantly higher systolic (139 mmHg vs 115 mmHg, p <0.05), diastolic BP (96 mmHg vs 79 mmHg, p <0.05), and serum levels of kynurenic acid (-9.76 vs -10.21, p <0.05) and 3-hydroxy kynurenine (-6.49 vs -7.34, p <0.01). Coupled with these increases in kynurenic pathway metabolites, microarray analyses demonstrated increased immune responses (e.g. Cd74, Il1b, Cxcl1, Mmp14 ) in the PVN (gene ontology analysis, p <0.001) and increased cell differentiation and synaptic plasticity (e.g. Sox11, Tp53, Cdk6, Hoxb4, Foxo4, Cyr61 ) in the NTS (gene ontology analysis, p <0.01).

Conclusion: Colonization of gut microbiota in GF rats induced increased cell differentiation and synaptic plasticity in the NTS and immune responses in the PVN, indicating the restructured sensory neurons of the NTS and enhanced sympathetic output from the PVN. These are in line with increased levels of kynurenic acid and 3-hydroxy kynurenine, and BP, respectively, suggesting that BP regulation by the gut-brain axis may be mediated by kynurenic pathway.

Abstract P238: Bile Acid Metabolites Modulate Hypertension

Hypertension is the single prominent risk factor of epidemic proportions leading to cardiovascular disease and stroke, which comprise the top two reasons for mortality of humans in the modern age. Much of the attention for the unknown causes of hypertension was focused on genetics and dietary salt, but in recent years, host-microbiotal interaction is gaining importance. Host-microbiotal partnership is key for the generation of many bioactive molecules including bile acid (BA) metabolites. Primary bile acids are synthesized and conjugated by the host but deconjugated and further modified to secondary BA by gut commensal bacteria. BA metabolites serve as important ligands for host nuclear receptors and/or G-protein-coupled receptors. These receptors have pivotal roles in blood pressure regulation. However, the effect of the host-microorganism biliary network on blood pressure (BP) remains poorly characterized. Here we report that both dietary salt and genetic factors rewire the composition of bile acids and BP. Specific reductions in conjugated bile acids were noted in human hypertensives as well as in rats with hypertension. Conjugation of bile acids by the host alone, devoid of the deconjugation step by microbiota, was sufficient to decrease BP of germ-free rats compared to germ-free conventionalized rats. Nutritional restoration of the conjugation of bile acids with Taurine increased the availability of circulating conjugated bile acids as ligands and ameliorated host susceptibility to hypertension via BA nuclear receptors and G-protein-coupled receptors. Thus, hosts and their bacterial symbionts can control host BP homeostasis via the resulting pool of bile acid metabolites. Sources of funding: National Institutes of Health (R01HL143082).

Diurnal Timing Dependent Alterations in Gut Microbial Composition Are Synchronously Linked to Salt-Sensitive Hypertension and Renal Damage

Alterations of diurnal rhythms of blood pressure (BP) and reshaping of gut microbiota are both independently associated with hypertension. However, the relationships between biorhythms of BP and gut microbial composition are unknown. We hypothesized that diurnal timing-associated alterations of microbial compositions are synchronous with diurnal rhythmicity, dip in BP, and renal function. To test this hypothesis, Dahl salt-sensitive (S) rats on low- and high-salt diets were examined for time of day effects on gut microbiota, BP, and indicators of renal damage. Major shifts in night and day patterns of specific groups of microbiota were observed between the dark (active) and light (rest) phases, which correlated with diurnal rhythmicity of BP. The diurnal abundance of Firmicutes, Bacteroidetes, and Actinobacteria were independently associated with BP. Discrete bacterial taxa were observed to correlate independently or interactively with one or more of the following 3 factors: (1) BP rhythm, (2) dietary salt, and (3) dip in BP. Phylogenetic Investigation of Communities revealed diurnal timing effects on microbial pathways, characterized by upregulated biosynthetic processes during the active phase of host, and upregulated degradation pathways of metabolites in the resting phase. Additional metagenomics functional pathways with rhythm variations were noted for aromatic amino acid metabolism and taurine metabolism. These diurnal timing dependent changes in microbiota, their functional pathways, and BP dip were associated with concerted effects of the levels of renal lipocalin 2 and kidney injury molecule-1 expression. These data provide evidence for a firm and concerted diurnal timing effects of BP, renal damage, and select microbial communities.

Microbial Reconstitution Reverses Early Female Puberty Induced by Maternal High-fat Diet During Lactation

Recent work shows that gut microbial dysbiosis contributes to the risk of obesity in children whose mothers consume a high-fat diet (HFD) during both gestation and lactation or during gestation alone. Obesity predisposes children to developing precocious puberty. However, to date, no study has examined how maternal HFD (MHFD) during lactation regulates the gut microbiota (GM), pubertal timing, and fertility of offspring. Here, we found that MHFD during lactation markedly altered the GM of offspring. The pups developed juvenile obesity, early puberty, irregular estrous cycles, and signs of disrupted glucose metabolism. Remarkably, permitting coprophagia between MHFD and maternal normal chow offspring successfully reversed the GM changes as well as early puberty and insulin insensitivity. Our data suggest that microbial reconstitution may prevent or treat early puberty associated with insulin resistance.

Exposure to Amoxicillin in Early Life Is Associated With Changes in Gut Microbiota and Reduction in Blood Pressure: Findings From a Study on Rat Dams and Offspring

Background

Pediatric hypertension is recognized as an emerging global health concern. Although new guidelines are developed for facilitating clinical management, the reasons for the prevalence of hypertension in children remain unknown. Genetics and environmental factors do not fully account for the growing incidence of pediatric hypertension. Because stable bacterial flora in early life are linked with health outcomes later in life, we hypothesized that reshaping of gut microbiota in early life affects blood pressure (BP) of pediatric subjects.

Methods and Results

To test this hypothesis, we administered amoxicillin, the most commonly prescribed pediatric antibiotic, to alter gut microbiota of young, genetically hypertensive rats (study 1) and dams during gestation and lactation (study 2) and recorded their BP. Reshaping of microbiota with reductions in Firmicutes/Bacteriodetes ratio were observed. Amoxicillin treated rats had lower BP compared with untreated rats. In young rats treated with amoxicillin, the lowering effect on BP persisted even after antibiotics were discontinued. Similarly, offspring from dams treated with amoxicillin showed lower systolic BP compared with control rats. Remarkably, in all cases, a decrease in BP was associated with lowering of Veillonellaceae, which are succinate‐producing bacteria. Elevated plasma succinate is reported in hypertension. Accordingly, serum succinate was measured and found lower in animals treated with amoxicillin.

Conclusions

Our results demonstrate a direct correlation between succinate‐producing gut microbiota and early development of hypertension and indicate that reshaping gut microbiota, especially by depleting succinate‐producing microbiota early in life, may have long‐term benefits for hypertension‐prone individuals.

Salt-Responsive Metabolite, β-Hydroxybutyrate, Attenuates Hypertension

Dietary salt reduction and exercise are lifestyle modifications for salt-sensitive hypertensives. While exercise has prominent metabolic effects, salt has an adverse effect on metabolic syndrome, of which hypertension is a hallmark. We hypothesized that dietary salt impacts metabolism in a salt-sensitive model of hypertension. An untargeted metabolomic approach demonstrates lower circulating levels of the ketone body, beta-hydroxybutyrate (βOHB), in high salt-fed hypertensive rats. Despite the high salt intake, specific rescue of βOHB levels by nutritional supplementation of its precursor, 1,3-butanediol, attenuates hypertension and protects kidney function. This beneficial effect of βOHB was likely independent of gut-microbiotal and Th17-mediated effects of salt and instead facilitated by βOHB inhibiting the renal Nlrp3 inflammasome. The juxtaposed effects of dietary salt and exercise on salt-sensitive hypertension, which decrease and increase βOHB respectively, indicate that nutritional supplementation of a precursor of βOHB provides a similar benefit to salt-sensitive hypertension as exercise.

Chakraborty et al. report a link between dietary salt, a ketone, and experimental hypertension. Intake of a high salt diet lowers the ketone body betahydroxybutyrate (βOHB), produced by the liver, which functions to prevent Nlrp3-mediated kidney inflammation. Rescuing βOHB by nutritional supplementation of its precursor attenuates hypertension.

Abstract P3027: Response to Exercise Dictates Metabolic and Microbiotal Effects of a High-Salt Diet With Aging

Individual variation in response to exercise could be critical to sustaining cardiorespiratory fitness with aging. In order to explore this idea, we developed preclinical animal models of low and high response trainer rats (LRT and HRT, respectively) by selective breeding based on change (Δ) in performance on a maximal treadmill running test after an 8-week standardized aerobic training program. To test the hypothesis that individuals with low adaptive capacity to exercise training (like LRT rats) are more vulnerable to the development of hypertension associated with aging compared to individuals with high adaptive ability (like HRT rats), we subjected 24-month old male rats to a high-salt diet (HSD, 2% NaCl) for 32 days and evaluated cardiovascular and metabolic responses. We observed no significant change in resting blood pressure (telemetry implants, DSI) after HSD suggesting neither strain is salt-sensitive (LRT vs. HRT before HSD, 115.9 vs. 120.8; after HSD, 112.4 vs. 118.4 mmHg). However, resting heart rate decreased in both strains in response to HSD (ΔLRT = -32.2 bpm and ΔHRT = -30.9 bpm). Metabolic evaluation (CLAMS, Columbus Instruments) showed LRT rats significantly decreased food intake (ΔLRT vs. ΔHRT, -9.64 vs. 3.86 g/kg/day; P < 0.01) and water consumption (ΔLRT vs. ΔHRT, -11.8 vs. 7.5 ml/kg/day; P < 0.05) after HSD compared to HRT. Interestingly, we found that the respiratory exchange ratio (RER) was significantly lowered in LRT rats (before HSD, 0.95; after HSD, 0.90; P < 0.05), but a trend of increasing RER occurred in HRT rats after HSD. Accordingly, we observed opposite and inverse trends in fat and glucose oxidation indicating that aged LRT and HRT rats reprioritize energy metabolism differently in response to HSD. Both strains maintained their normal body weight and plasma concentration of sodium while coping with HSD. In addition, 16S rRNA profiling of fecal samples revealed that the relative abundance of several gut bacteria including Lactobacillaceae and Turicibacteraceae increased in LRT rats (ΔLRT, 5.6% and 4.6% respectively) but not in HRT rats. Together, these data suggest that rats bred for their ability to respond to exercise adapt differently to a HSD in order to maintain cardiovascular and metabolic homeostasis.

Differentiation and behavior of human neural progenitors on micropatterned substrates and in the developing retina

In this study we investigated the differentiation of human neural progenitor cells (hNPCs) in vitro to evaluate their differentiation potential and in vivo to explore their viability and behavior following transplantation. Progenitors were maintained as neurospheres in media containing basic fibroblast growth factor and epidermal growth factor. Micropatterned polystyrene substrates were fabricated and coated with ECL (entactin, collagen, and laminin) to provide physical and chemical guidance during the differentiation of the hNPCs. The hNPCs growing on the micropatterned substrates showed no differences in proliferation or differentiation potential compared with those hNPCs growing on the nonpatterned substrates. However, hNPCs cultured on the micropatterned substrates were aligned in the direction of the micropattern compared with those cells growing on the nonpatterned substrates. Furthermore, hNPC migration was directed in alignment with the micropatterned substrates. Transplantation of the hNPCs into the developing retina was used to evaluate their behavior in vivo. Cells displayed extensive survival, differentiation, and morphological integration following xenotransplant into the retina, even in the absence of immunosuppression. Taken together, our results show that these multipotent hNPCs are a neurogenic progenitor population that can be maintained in culture for extended periods. Although the micropatterned substrates have no major effect on the proliferation or differentiation of the hNPCs, they clearly promoted alignment and directed neurite outgrowth along the pattern as well as directing migration of the cells. These approaches may provide important strategies to guide the growth and differentiation of NPCs in vitro and in vivo.

Parvalbumin-immunoreactive neurons in the inner nuclear layer of zebrafish retina

The purpose of this investigation is to characterize parvalbumin-immunoreactive (IR) neurons in the inner nuclear layer (INL) of zebrafish retina through immunocytochemistry, quantitative analysis, and confocal microscopy. In the INL, parvalbumin-IR neurons were located in the inner marginal portion of the INL. On the basis of dendritic stratification in the inner plexiform layer (IPL), at least two types of amacrine cells were IR for parvalbumin. The first one formed distinctive laminar tiers within s4 (PVs4) of the IPL, and the second within s5 (PVs5). The average number of PVs4 cells was 8263 cells per retina (n=3), and the mean density was 1671cells/mm(2). The average number of PVs5 cells was 1037 cells per retina (n=3), and the mean density was 210cells/mm(2). Quantitatively, 88.9% of anti-parvalbumin labeled neurons were PVs4 cells and 11.1% were PVs5 cells. Their density was highest in the midcentral region of the ventrotemporal retina and lowest in the periphery of the dorsonasal retina. The average regularity index of the PVs4 cell mosaic was 4.09, while the average regularity index of the PVs5 cell mosaic was 3.46. No parvalbumin-IR cells expressed calretinin or disabled-1, markers for AII amacrine cells, in several animals. These results indicate that parvalbumin-IR neurons in zebrafish are limited to specific subpopulations of amacrine cells and the expressional pattern of parvalbumin may not correspond to AII amacrine cells in several other animals. Their distribution suggests that parvalbumin-IR neurons are mainly involved in ON pathway information flow.

The anti-diabetic effects of ethanol extract from two variants of Artemisia princeps Pampanini in C57BL/KsJ-db/db mice

The anti-diabetic effects of two variants of Artemisia princeps Pampanini, sajabalssuk (SB) and sajuarissuk (SS), were investigated in type 2 diabetic animal using their ethanol extracts. Male C57BL/KsJ-db/db (db/db) mice were divided into control, SB ethanol extract (SBE), SS ethanol extract (SSE), or rosiglitazone (RG) groups and their age-matched littermates (db/+) were used. Supplementation of the SBE (0.171 g/100g diet), SSE (0.154 g/100g diet), and RG (0.005 g/100g diet) improved glucose and insulin tolerance and significantly lowered blood glycosylated hemoglobin levels, as compared to the control group. Plasma insulin, C-peptide and glucagon levels in db/db mice were higher in the db/+ mice, however these values were significantly lowered by SBE, SSE or RG-supplement. Hepatic GK activity was significantly lower in the db/db mice than in the db/+ mice, while hepatic G6Pase activity was vice versa. Supplementation of SBE, SSE and RG reversed these hepatic glucose-regulating enzyme activities. In addition, SBE and SSE markedly increased the hepatic glycogen content and muscle ratio as compared to the control group, but they did not alter the food intake, body weight and plasma leptin level. The RG group, however, showed a significant increase in the food intake, body weight and plasma leptin. These results suggest that SBE and SSE exert an anti-diabetic effect in type 2 diabetic mice.