Contrasting nutrient-disease relationships: Potassium gradients in barley leaves have opposite effects on two fungal pathogens with different sensitivities to jasmonic acid

Understanding the interactions between mineral nutrition and disease is essential for crop management. Our previous studies with Arabidopsis thaliana demonstrated that potassium (K) deprivation induced the biosynthesis of jasmonate (JA) and increased the plant's resistance to herbivorous insects. Here we addressed the question how tissue K affects the development of fungal pathogens and whether sensitivity of the pathogens to JA could play a role for the K‐disease relationship in barley (Hordeum vulgare cv. Optic). We report that K‐deprived barley plants showed increased leaf concentrations of JA and other oxylipins. Furthermore, a natural tip‐to base K‐concentrations gradient within leaves of K‐sufficient plants was quantitatively mirrored by the transcript levels of JA‐responsive genes. The local leaf tissue K concentrations affected the development of two economically important fungi in opposite ways, showing a positive correlation with powdery mildew (Blumeria graminis) and a negative correlation with leaf scald (Rhynchosporium commune) disease symptoms. B. graminis induced a JA‐response in the plant and was sensitive to methyl‐JA treatment while R. commune initiated no JA‐response and was JA‐insensitive. Our study challenges the view that high K generally improves plant health and suggests that JA‐sensitivity of pathogens could be an important factor determining the exact K‐disease relationship

High resolution molecular and histological analysis of renal disease progression in ZSF1 fa/faCP rats, a model of type 2 diabetic nephropathy.

ZSF1 rats exhibit spontaneous nephropathy secondary to obesity, hypertension, and diabetes, and have gained interest as a model system with potentially high translational value to progressive human disease. To thoroughly characterize this model, and to better understand how closely it recapitulates human disease, we performed a high resolution longitudinal analysis of renal disease progression in ZSF1 rats spanning from early disease to end stage renal disease. Analyses included metabolic endpoints, renal histology and ultrastructure, evaluation of a urinary biomarker of fibrosis, and transcriptome analysis of glomerular-enriched tissue over the course of disease. Our findings support the translational value of the ZSF1 rat model, and are provided here to assist researchers in the determination of the model's suitability for testing a particular mechanism of interest, the design of therapeutic intervention studies, and the identification of new targets and biomarkers for type 2 diabetic nephropathy

A protein kinase C α and β inhibitor blunts hyperphagia to halt renal function decline and reduces adiposity in a rat model of obesity-driven type 2 diabetes

Abstract Type 2 diabetes (T2D) and its complications can have debilitating, sometimes fatal consequences for afflicted individuals. The disease can be difficult to control, and therapeutic strategies to prevent T2D-induced tissue and organ damage are needed. Here we describe the results of administering a potent and selective inhibitor of Protein Kinase C (PKC) family members PKCα and PKCβ, Cmpd 1, in the ZSF1 obese rat model of hyperphagia-induced, obesity-driven T2D. Although our initial intent was to evaluate the effect of PKCα/β inhibition on renal damage in this model setting, Cmpd 1 unexpectedly caused a marked reduction in the hyperphagic response of ZSF1 obese animals. This halted renal function decline but did so indirectly and indistinguishably from a pair feeding comparator group. However, above and beyond this food intake effect, Cmpd 1 lowered overall animal body weights, reduced liver vacuolation, and reduced inguinal adipose tissue (iWAT) mass, inflammation, and adipocyte size. Taken together, Cmpd 1 had strong effects on multiple disease parameters in this obesity-driven rodent model of T2D. Further evaluation for potential translation of PKCα/β inhibition to T2D and obesity in humans is warranted

Obese ZSF1 have histologically evident renal fibrosis by 20 weeks of age that worsens over time.

<p>(A-D) Kidney section from a 34-week-old obese rat stained with (A) hematoxylin and eosin (H & E), (B) Periodic Acid Schiff (PAS), (C) Collagen IV (COL IV) IHC, or (D) trichrome. Highlighted features are as follows: (A) hyaline casts and proteinaceous material in dilated tubules (asterisk), thickened glomerular basement membranes (long arrows), and leukocytic infiltrates (short arrows); (B) thickened mesangial matrix (arrows); (C) increased deposition of collagen IV in glomerular mesangial matrix and basement membranes (asterisk and arrows); and (D) increased collagen in mesangial matrix (asterisk and arrows). (E) Glomerular tuft area as determined from H & E staining. (F) PAS positive glomerular mesangial area. (G) Results from Collagen IV immunohistochemistry expressed as Col IV staining area per glomerulus. (H) Results from blinded semi-quantitative trichrome staining for fibrosis severity.</p

Longitudinal expression profiles of top p-value ranked transcripts in glomerular-enriched tissue from a comparison of 41-week-old animals.

<p>The top 18 genes from this analysis are presented in alphabetical order. Obese animals are represented by open circles, and lean animals by closed circles. Data are plotted as log2 RPKM reads per kilobase per million reads (RPKM).</p

Levels of urinary Collagen type III breakdown product (uC3M) positively correlate with renal fibrosis and renal function decline in ZSF1 rats.

<p>(A) Levels of uC3M as determined by ELISA for the MMP9-generated neoepitope KNGETGPQGP, normalized to urine creatinine levels, in all animals over the study duration. Correlation of uC3M to creatinine levels versus Collagen type IV staining area per glomerulus (B), semi-quantitative trichrome staining (C), and microalbumin to creatinine ratios (D). R² values, shown, were determined by linear regression of all values with obese animals represented by open circles and lean animals represented by filled circles.</p

Nephropathy in obese ZSF1 rats is accompanied by ultrastructural changes in glomeruli and proximal tubular epithelial cells (PTEC).

<p>TEM of glomeruli (A) and PTEC (B) of a representative 41-week-old lean animal, and of representative 29-, 34-, and 41-week-old obese animals. Obesity and age-related findings were glomerular basement membrane thickening (b), podocyte foot process effacement (p), mesangial nodules (n) in glomerular capillary lumens, and increased mesangial matrix (m). Findings that were related to obesity, but not age, were glomerular lipid droplets (d) in mesangial cells, proximal tubular basement membrane thickening (t), and cytoplasmic membrane whorls (w). (Lead citrate/uranyl acetate, Magnification = 5,000x for A, and 2,000x for B).</p

Pathway analysis reveals good concordance between weeks 34 and 41 obese ZSF1 animals and a published dataset of human DN glomeruli.

<p>Gene expression changes in glomerular-enriched tissues from obese ZSF1 rats at 12, 19, 24, 29, 34, and 41 weeks of age were from a comparison with age-matched littermates. Differentially expressed genes (DEGs) were populated in IPA Knowledge Base for pathway enrichment analysis. Gene expression changes in human type 2 DN were from Hodgin <i>et al</i>, and are of micro-dissected glomeruli analyzed by Affymetrix microarray [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181861#pone.0181861.ref039" target="_blank">39</a>]. A p-value was calculated using a right-tailed Fisher’s exact test to determine statistically significant over-representation of genes in any known canonical pathway. Activation Z scores indicate activation and inhibition of the pathways with |2| as threshold for significance. Numbers colored in red indicate pathway activation, while those in blue indicate pathway inhibition.</p

Obese ZSF1 rats have metabolic syndrome and evidence of renal impairment by 12 weeks of age.

<p>(A) Serum total cholesterol, (B) serum triglycerides, (C) serum blood urea nitrogen (BUN), (D) urinary microalbumin to creatinine ratio, (E) urinary NGAL to creatinine ratio, and (F) urinary Kim-1 to creatinine ratio in lean and obese animals over the study duration. Each point represents a single animal, with obese animals represented by open circles and lean animals represented by filled circles. Statistical analyses, here and in subsequent Figures, are for each obese group versus age-matched lean group (denoted by *) or for each obese group versus the 12-week-old obese group (denoted by †) using two-way ANOVA Tukey’s multiple comparisons tests.</p