Which factors influence Demodex mite density in standardized superficial skin biopsy in patients with rosacea? A prospective cross-sectional analysis.

Rosacea is a chronic cutaneous disease that manifests with facial erythema, telangiectasia, papules and pustules on the central face. Although the pathogenesis is not well established, rosacea appears to have a close relationship with Demodex mites. The aim of the study was to elucidate the factors influencing Demodex mite density by standardized superficial skin biopsy (SSSB) in patients with rosacea. This prospective, cross-sectional study included 200 patients with rosacea. Clinical characteristics of the patients were recorded and SSSB was used to measure Demodex density (Dd). If Dd was < 5 D/cm2 in the first SSSB, SSSB was repeated 4 more times to avoid false negative results. Of 200 patients, 152 (76%) were females and 48 (24%) males with a mean age of 43.47 ± 11.87 years. Ninety-nine patients (49.5%) had erythematotelangiectatic (ETR) and 101 patients (50.5%) had papulopustular (PPR) subtype of rosacea. Among 200 patients, the ratio of cumulative positive results of the consecutive SSSBs were as follows: 1st SSSB = 125 (62.5%), 2nd SSSB = 155 (77.5%), 3rd SSSB = 170 (85%), 4th SSSB = 173 (86.5%) and 5th SSSB = 174 (87%). The ratio of detecting Demodex infestation in the first SSSB was significantly lower in patients with PPR (55/101, 54.5%) than in patients with ETR (70/99, 70.7%). Median total Demodex mite density and D. folliculorum density were significantly higher in the ETR group than in the PPR group. There was a statistically significant relationship between density of Demodex tails in dermoscopy and positive/negative results of Demodex infestation in SSSB. As a conclusion, Demodex mite density by SSSB was influenced by various factors such as subtypes of rosacea, types of Demodex species, and dermoscopic findings.

The effect of COVID-19 on development of hair and nail disorders: a Turkish multicenter, controlled study.

BACKGROUND: A broad spectrum of skin diseases, including hair and nails, can be directly or indirectly triggered by COVID-19. It is aimed to examine the type and frequency of hair and nail disorders after COVID-19 infection. METHODS: This is a multicenter study conducted on consecutive 2171 post-COVID-19 patients. Patients who developed hair and nail disorders and did not develop hair and nail disorders were recruited as subject and control groups. The type and frequency of hair and nail disorders were examined. RESULTS: The rate of the previous admission in hospital due to COVID-19 was statistically significantly more common in patients who developed hair loss after getting infected with COVID-19 (P < 0.001). Telogen effluvium (85%) was the most common hair loss type followed by worsening of androgenetic alopecia (7%) after COVID-19 infection. The mean stress scores during and after getting infected with COVID-19 were 6.88 ± 2.77 and 3.64 ± 3.04, respectively, in the hair loss group and were 5.77 ± 3.18 and 2.81 ± 2.84, respectively, in the control group (P < 0.001, P < 0.001). The frequency of recurrent COVID-19 was statistically significantly higher in men with severe androgenetic alopecia (Grades 4-7 HNS) (P = 0.012; Odds ratio: 2.931 [1.222-7.027]). The most common nail disorders were leukonychia, onycholysis, Beau's lines, onychomadesis, and onychoschisis, respectively. The symptoms of COVID-19 were statistically significantly more common in patients having nail disorders after getting infected with COVID-19 when compared to the control group (P < 0.05). CONCLUSION: The development of both nail and hair disorders after COVID-19 seems to be related to a history of severe COVID-19.

Comparison of the psychosocial impact of acne in adolescents and adults; body satisfaction, self-esteem, and quality of life.

BACKGROUND: Dermatological diseases, including acne vulgaris, have significant psychosocial effects on patients. AIMS: To compare body satisfaction, self-esteem, and quality of life (QoL) in adolescents and adults with acne. METHODS: A total of 192 acne patients (132 female, 60 male; aged 19.42 ± 3.50 years) were included in the study. Global Acne Grading System, Rosenberg Self-Esteem Scale (RSES), Turkish Acne Quality of Life Index (TAQoLI), and Body Cathexis Scale (BCS) were used. The patients were divided into two groups: under 20 years old (adolescents) and 20 years and above (adults). RESULTS: The mean RSES score was found as 19.49 ± 5.11, the mean BCS score was 143.95 ± 20.92 and the mean TAQoLI score was 23.44 ± 10.02. There was no difference between adolescents and adults in terms of the mean value of the RSES score, TAQoLI score, and BCS score (p > 0.05). But, the proportion of those whose RSES score is below 15 is higher in patients under 20 years of age (28%) than patients aged 20 and over (14%) (p < 0.05). Linear regression analysis revealed that the most important determinant of body satisfaction was self-esteem (ß = 0.287, p < 0.05), the most important determinants of self-esteem were body satisfaction (ß = 0.208, p < 0.05), QoL (ß = -0.398, p < 0.001), and education level (ß = 0.245, p = 0.007) and, one of the most important determinant of QoL was self-esteem (ß = -0.403, p < 0.001). CONCLUSIONS: This study demonstrates that acne vulgaris negatively affects an individual's body satisfaction, self-esteem, and QoL. The psychosocial burden of acne is as significant for adults as for adolescents. Body satisfaction, self-esteem, and QoL are in interaction with each other.

The course of acne in healthcare workers during the COVID-19 pandemic and evaluation of possible risk factors.

BACKGROUND: There are a limited number of publications reporting an increase in acne in the COVID-19 outbreak. OBJECTIVE: The study aimed to evaluate the course and the clinical features of acne and possible risk factors during the COVID-19 pandemic in healthcare workers. METHOD: A total of 172 physicians (female, n = 159, male; n = 13, mean age = 35.03 ± 5.27 years) who had acne in any period of their life were included in the study. A self-administered online questionnaire was applied. RESULTS: During the COVID-19 pandemic, 45.35% of the participants reported that their acne complaints increased, 27.33% reported relapses, and 7.56% reported occurrence for the first time. Newly formed acne was reported most frequently on the chin (78.26%). The number of female participants, smoking, increased stress, and the rate of surgical mask use were found to be higher in the group whose acne occurred for the first time, relapsed, or increased than in the group whose acne complaints were unchanged or decreased (p < 0.05). In the group whose acne relapsed or increased, adult-onset acne, presence of scar, and use of systemic acne treatment before the COVID-19 pandemic were more common than in the group whose acne complaints were unchanged or decreased (p < 0.05). CONCLUSION: Almost half of the participants reported an increase in acne. More than a third of the participants reported that their acne relapsed or they had acne for the first time. In addition to the use of surgical masks, factors such as increased stress, smoking, adult-onset acne, presence of scar, and previous systemic acne treatment were found to be responsible for acne development.

New-onset or Exacerbated Occupational Hand Eczema among Healthcare Workers During the COVID-19 Pandemic: A Growing Health Problem.

Hand hygiene is one of the cornerstones in ensuring effective infection control during the Coronavirus disease 2019 (COVID-19) outbreak. We aimed to investigate the prevalence of new-onset occupational HE during the COVID-19 outbreak in healthcare workers (HCWs) and the clinical course, clinical features, and risk factors of occupational hand eczema (HE). A total of 159 volunteer HCWs (female: n=112; male: n=47, mean age=35.55±7.03 years) working in a pandemic hospital were included. Participants were questioned in terms of daily hand hygiene, use of gloves, and signs and symptoms associated with HE before and during the COVID-19 pandemic. HCWs were divided into two groups classified as non-COVID and COVID, according to the unit they worked in. In our study, 55 participants reported new-onset signs and/or symptoms associated with HE during the COVID-19 pandemic. 59 participants described an increase in signs and/or symptoms associated with HE. The presence of newly-formed or increased signs and/or symptoms associated with HE was found to be 71.7%. A significant increase in dryness, itching, pain/burning, erythema, and scaling was observed (P<0.05). No difference was found between the COVID and non-COVID groups in terms of newly formed and/or increased signs and symptoms (P>0.05). The study included a limited number of participants, and the participants self-reported the signs and symptoms associated with HE. During the COVID-19 period, there has been a significant increase in the signs and symptoms of occupational HE as a result of increased hand hygiene practices in HCWs.

Internalized stigma: One of the main factors responsible for the psychosocial burden of melasma?

BACKGROUND: Internalized stigma is the acceptance of negative stereotypes about the disease created by society and withdrawing self from society with emotions such as worthlessness and shame. AIMS: This study aimed to investigate the internalized stigma state of patients with melasma, and to identify the factors affecting the internalized stigma. METHODS: A total of 55 melasma patients were included. The sociodemographic and clinical characteristics of the patients were recorded. Melasma Severity Index, the Turkish version of the Melasma Quality of Life Scale (MelasQoL-TR), and Internalized Stigma Scale (ISS) were used. Besides, patients answered the Perceived Health Status (PHS) and the General Health Questionnaire 12 scales (GHQ-12) surveys. RESULTS: The mean ISS total score was found as 49.49 ± 13.15. Cronbach's alpha coefficient for the whole scale was calculated as 0.92 for melasma patients. There was a significant correlation between the ISS total score and MelasQoL-TR (r = 0.608, P < .001). Besides, statistically significant positive correlations were also found between the overall scores of ISS and GHQ-12 (r = 0.578, P < .001). Linear regression analysis revealed that the most important determinant of internalized stigma was MelasQoL-TR (ß = 0.313, P < .001). CONCLUSIONS: This study demonstrates that patients with melasma internalize the negative stereotype judgments of the society about the disease. High levels of internalized stigma are related to poor quality of life and psychological illnesses. Therefore, internalized stigma may be one of the main factors responsible for the psychosocial burden of melasma.

Different subpopulations of kidney interstitial cells produce erythropoietin and factors supporting tissue oxygenation in response to hypoxia in vivo.

Genetic induction of hypoxia signaling by deletion of the von Hippel-Lindau (Vhl) protein in mesenchymal PDGFR-ß+ cells leads to abundant HIF-2 dependent erythropoietin (EPO) expression in the cortex and outer medulla of the kidney. This rather unique feature of kidney PDGFR-ß+ cells promote questions about their special characteristics and general functional response to hypoxia. To address these issues, we characterized kidney PDGFR-ß+ EPO expressing cells based on additional cell markers and their gene expression profile in response to hypoxia signaling induced by targeted deletion of Vhl or exposure to low oxygen and carbon monoxide respectively, and after unilateral ureteral obstruction. CD73+, Gli1+, tenascin C+ and interstitial SMMHC+ cells were identified as zonally distributed subpopulations of PDGFR-ß+ cells. EPO expression could be induced by Vhl deletion in all PDGFR-ß+ subpopulations. Under hypoxemic conditions, recruited EPO+ cells were mostly part of the CD73+ subpopulation. Besides EPO production, expression of adrenomedullin and regulator of G-protein signaling 4 was upregulated in PDGFR-ß+ subpopulations in response to the different hypoxic stimuli. Thus, different kidney interstitial PDGFR-ß+ subpopulations exist, capable of producing EPO in response to different stimuli. Activation of hypoxia signaling in these cells also induces factors likely contributing to improved kidney interstitial tissue oxygenation.

Activation of Hypoxia Signaling in Stromal Progenitors Impairs Kidney Development.

Intrauterine hypoxia is a reason for impaired kidney development. The cellular and molecular pathways along which hypoxia exerts effects on nephrogenesis are not well understood. They are likely triggered by hypoxia-inducible transcription factors (HIFs), and their effects appear to be dependent on the cell compartment contributing to kidney formation. In this study, we investigated the effects of HIF activation in the developing renal stroma, which also essentially modulates nephron development from the metanephric mesenchyme. HIF activation was achieved by conditional deletion of the von Hippel-Lindau tumor suppressor (VHL) protein in the forkhead box FOXD1 cell lineage, from which stromal progenitors arise. The resulting kidneys showed maturation defects associated with early postnatal death. In particular, nephron formation, tubular maturation, and the differentiation of smooth muscle, renin, and mesangial cells were impaired. Erythropoietin expression was strongly enhanced. Codeletion of VHL together with HIF2A but not with HIF1A led to apparently normal kidneys, and the animals reached normal age but were anemic because of low erythropoietin levels. Stromal deletion of HIF2A or HIF1A alone did not affect kidney development. These findings emphasize the relevance of sufficient intrauterine oxygenation for normal renal stroma differentiation, suggesting that chronic activity of HIF2 in stromal progenitors impairs kidney development. Finally, these data confirm the concept that normal stroma function is essential for normal tubular differentiation.

Albuminuria is associated with an increased prostasin in urine while aldosterone has no direct effect on urine and kidney tissue abundance of prostasin.

The proteinase prostasin is a candidate mediator for aldosterone-driven proteolytic activation of the epithelial sodium channel (ENaC). It was hypothesized that the aldosterone-mineralocorticoid receptor (MR) pathway stimulates prostasin abundance in kidney and urine. Prostasin was measured in plasma and urine from type 2 diabetic patients with resistant hypertension (n = 112) randomized to spironolactone/placebo in a clinical trial. Prostasin protein level was assessed by immunoblotting in (1) human and rat urines with/without nephrotic syndrome, (2) human nephrectomy tissue, (3) urine and kidney from aldosterone synthase-deficient (AS-/-) mice and ANGII- and aldosterone-infused mice, and in (4) kidney from adrenalectomized rats. Serum aldosterone concentration related to prostasin concentration in urine but not in plasma. Plasma prostasin concentration increased significantly after spironolactone compared to control. Urinary prostasin and albumin related directly and were reduced by spironolactone. In patients with nephrotic syndrome, urinary prostasin protein was elevated compared to controls. In rat nephrosis, proteinuria coincided with increased urinary prostasin, unchanged kidney tissue prostasin, and decreased plasma prostasin while plasma aldosterone was suppressed. Prostasin protein abundance in human nephrectomy tissue was similar across gender and ANGII inhibition regimens. Prostasin urine abundance was not different in AS-/- and aldosterone-infused mice. Prostasin kidney level was not different from control in adrenalectomized rats and AS-/- mice. We found no evidence for a direct relationship between mineralocorticoid receptor signaling and kidney and urine prostasin abundance. The reduction of urinary prostasin in spironolactone-treated patients is most likely the result of an improved glomerular filtration barrier function and generally reduced proteinuria.

Erythropoietin production by PDGFR-ß(+) cells.

PDGFR-ß-expressing cells of the kidneys are considered as a relevant site of erythropoietin (EPO) production. The origin of these cells, their contribution to renal EPO production, and if PDGFR-ß-positive cells in other organs are also capable to express EPO are less clear. We addressed these questions in mice, in which hypoxia-inducible transcription factors were stabilized in PDGFR-ß(+) cells by inducible deletion of the von Hippel-Lindau (Vhl) protein. Vhl deletion led to a 600-fold increase of plasma EPO concentration, 170-fold increase of renal EPO messenger RNA (mRNA) levels, and an increase of hematocrit values up to 70 %. Intrarenal localization of EPO-expressing cells coincided with the zonal heterogeneity and distribution of cells expressing PDGFR-ß. Amongst a variety of extrarenal organs only adrenal glands showed significant EPO mRNA expression after Vhl deletion in PDGFR-ß(+) cells. EPO mRNA, plasma EPO, and hematocrit fell to subnormal values if HIF-2α, but not HIF-1α, was deleted either alone or in combination with Vhl in PDGFR-ß(+) cells. Treatment of mice with a prolyl-hydroxylase inhibitor caused an increase of EPO mRNA abundance and plasma EPO concentrations in wild-type mice and in mice lacking HIF-1α in PDGFR-ß(+) cells but exerted no effect in mice lacking HIF-2α in PDGFR-ß(+) cells. These findings suggest that PDGFR-ß(+) cells are the only relevant site of EPO expression in the kidney and that HIF-2 is the essential transcription factor triggering EPO expression therein. Moreover, our findings suggest that PDGFR-ß(+) cells elaborating EPO might arise from the metanephric mesenchyme, rather than from the neural crest.

Piezo1-dependent regulation of urinary osmolarity.

The collecting duct (CD) is the final segment of the kidney involved in the fine regulation of osmotic and ionic balance. During dehydration, arginine vasopressin (AVP) stimulates the expression and trafficking of aquaporin 2 (AQP2) to the apical membrane of CD principal cells, thereby allowing water reabsorption from the primary urine. Conversely, when the secretion of AVP is lowered, as for instance upon water ingestion or as a consequence of diabetes insipidus, the CD remains water impermeable leading to enhanced diuresis and urine dilution. In addition, an AVP-independent mechanism of urine dilution is also at play when fasting. Piezo1/2 are recently discovered essential components of the non-selective mechanically activated cationic channels. Using quantitative PCR analysis and taking advantage of a ß-galactosidase reporter mouse, we demonstrate that Piezo1 is preferentially expressed in CD principal cells of the inner medulla at the adult stage, unlike Piezo2. Remarkably, siRNAs knock-down or conditional genetic deletion of Piezo1 specifically in renal cells fully suppresses activity of the stretch-activated non-selective cationic channels (SACs). Piezo1 in CD cells is dispensable for urine concentration upon dehydration. However, urinary dilution and decrease in urea concentration following rehydration are both significantly delayed in the absence of Piezo1. Moreover, decreases in urine osmolarity and urea concentration associated with fasting are fully impaired upon Piezo1 deletion in CD cells. Altogether, these findings indicate that Piezo1 is critically required for SAC activity in CD principal cells and is implicated in urinary osmoregulation.

Inducible glomerular erythropoietin production in the adult kidney.

Hypoxia-inducible factor (HIF)-2-triggered erythropoietin production in renal interstitial fibroblast-like cells is the physiologically relevant source of erythropoietin for regulating erythropoiesis. During renal fibrosis, these cells transform into myofibroblasts and lose their ability to produce sufficient erythropoietin leading to anemia. To find if other cells for erythropoietin production might exist in the kidney we tested for the capability of nonepithelial glomerular cells to elaborate erythropoietin. Therefore, HIF transcription factors were stabilized by cell-specific deletion of the von Hippel-Lindau (VHL) gene. Inducible deletion of VHL in glomerular connexin40-expressing cells (endothelial, renin-expressing, and mesangial cells) markedly increased glomerular erythropoietin mRNA expression levels, plasma erythropoietin concentrations, and hematocrit values. These changes were mimicked by inducible cell-specific VHL deletion in renin-expressing and in mesangial cells but not in endothelial cells. The increases of erythropoietin production were absent, when VHL was co-deleted with HIF-2. The induction of glomerular erythropoietin expression was associated with the downregulation of juxtaglomerular renin expression, again in a HIF-2-dependent manner. Thus, VHL deletion in renin-expressing and in mesangial cells induces the capability to produce relevant amounts of erythropoietin and to suppress renin expression in the adult kidney if HIF-2 is stabilized.

Plasticity of renal endocrine function.

The kidneys are important endocrine organs. They secrete humoral factors, such as calcitriol, erythropoietin, klotho, and renin into the circulation, and therefore, they are essentially involved in the regulation of a variety of processes ranging from bone formation to erythropoiesis. The endocrine functions are established by cells, such as proximal or distal tubular cells, renocortical interstitial cells, or mural cells of afferent arterioles. These endocrine cells are either fixed in number, such as tubular cells, which individually and gradually upregulate or downregulate hormone production, or they belong to a pool of cells, which display a recruitment behavior, such as erythropoietin- and renin-producing cells. In the latter case, regulation of humoral function occurs via (de)recruitment of active endocrine cells. As a consequence renin- and erythropoietin-producing cells in the kidney show a high degree of plasticity by reversibly switching between distinct cell states. In this review, we will focus on the characteristics of renin- and of erythropoietin-producing cells, especially on their origin and localization, their reversible transformations, and the mediators, which are responsible for transformation. Finally, we will discuss a possible interconversion of renin and erythropoietin expression.

Inducible deletion of connexin 40 in adult mice causes hypertension and disrupts pressure control of renin secretion.

Genetic loss-of-function defects of connexin 40 in renal juxtaglomerular cells are associated with renin-dependent hypertension. The dysregulation of renin secretion results from an intrarenal displacement of renin cells and an interruption of the negative feedback control of renin secretion by blood pressure. It is unknown whether this phenotype is secondary to developmental defects of juxtaglomerular renin cells due to connexin 40 malfunction, or whether acute functional defects of connexin 40 in the normal adult kidney can also lead to a similar dysregulation of renin secretion and hypertension. To address this question, we generated mice with an inducible deletion of connexin 40 in the adult kidney by crossing connexin 40-floxed mice with mice harboring a ubiquitously expressed tamoxifen-inducible Cre recombinase. Tamoxifen treatment in these mice strongly reduced connexin 40 mRNA and protein expression in the kidneys. These mice displayed persistent hypertension with renin expression shifted from the media layer of afferent arterioles to juxtaglomerular periglomerular cells. Control of renin secretion by the perfusion pressure was abolished in vitro, whereas in vivo plasma renin concentrations were increased. Thus, interruption of the connexin 40 gene in the adult kidney produced very similar changes in the renin system as had embryonic deletion. Hence, impairments of connexin 40 function in the normal adult kidney can cause renin-dependent hypertension.

Connexin 43 is not essential for the control of renin synthesis and secretion.

The juxtaglomerular areas of mammalian kidneys express the gap junction proteins connexin 37, 40, 43, and 45. Among these, Cx40 plays a major role for the function of juxtaglomerular renin-expressing cells, while Cx37 and Cx45 appear to be less relevant in this context. Since the role of the remaining Cx43 for the function of renin expression is not well understood, this study aimed to systematically characterize the direct role of Cx43 for renin expression and secretion. For this aim, we generated mice with endothelium and with renin cell-specific deletions of Cx43, and we characterized the regulation of renin expression and renin secretion in the kidneys of these mice on normal salt diet and during chronic challenge of the renin system by pretreatment of mice with a low-salt diet in combination with an angiotensin I-converting enzyme inhibitor. We found that renal renin mRNA abundance, plasma renin concentration, and systolic blood pressure did not differ between wild-type, Cx43(fl/fl) Ren1d(+/Cre) mice as well as Cx43(fl/fl) Tie-2(+/Cre) mice under basal conditions nor under chronic stimulation by salt depletion. The localization of renin-expressing cells was also regular in kidneys of all genotypes, and moreover, regulation of renin secretion by beta-adrenergic stimulation and renal perfusion pressure measured in isolated perfused kidneys of Cx43(fl/fl) Ren1d(+/Cre) and Cx43(fl/fl) Tie-2(+/Cre) mice was not different from control. We infer from these results that Cx43 plays if at all only a minor role for the functional control of renin-producing cells in the kidney.

Control of renin secretion from kidneys with renin cell hyperplasia.

In states of loss-of-function mutations of the renin-angiotensin-aldosterone system, kidneys develop a strong hyperplasia of renin-producing cells. Those additional renin cells are located outside the classic juxtaglomerular areas, mainly in the walls of preglomerular vessels and most prominently in multilayers surrounding afferent arterioles. Since the functional behavior of those ectopic renin cells is yet unknown, we aimed to characterize the control of renin secretion from kidneys with renin cell hyperplasia. As a model, we used kidneys from mice lacking aldosterone synthase (AS⁻/⁻ mice), which displayed 10-fold elevations of renin mRNA and plasma renin concentrations. On the absolute level, renin secretion from isolated AS⁻/⁻ kidneys was more than 10-fold increased over wild-type kidneys. On the relative level, the stimulation of renin secretion by the ß-adrenergic activator isoproterenol or by lowering of the concentration of extracellular Ca²âº was very similar between the two genotypes. In addition, the inhibitory effects of ANG II and of perfusion pressure were similar between the two genotypes. Deletion of connexin40 blunted the pressure dependency of renin secretion and the stimulatory effect of low extracellular Ca²âº on renin secretion in the same manner in kidneys of AS⁻/⁻ mice as in wild-type mice. Our findings suggest a high degree of functional similarity between renin cells originating during development and located at different positions in the adult kidney. They also suggest a high similarity in the expression of membrane proteins relevant for the control of renin secretion, such as ß1-adrenergic receptors, ANG II type 1 receptors, and connexin40.

High-level connexin expression in the human juxtaglomerular apparatus.

Recent evidence obtained in rodents indicates that gap junctions in the juxtaglomerular apparatus play an important role in the control of renin-producing cells and in tubuloglomerular signaling. These gap junctions are formed by cell-specific expression patterns of the vascular connexins Cx37, Cx40, Cx43 and Cx45. In order to obtain a first indication if gap junctions might play a similar important functional role in the juxtaglomerular apparatus of human kidneys, this study aimed to characterize the juxtaglomerular localization of Cx40, Cx37, Cx43 and Cx45 in human kidney specimens. We found Cx37, Cx40 and Cx43, but not Cx45 expression in high density in the extraglomerular mesangium. Renin-producing cells displayed strong immunoreactivity for Cx40 and Cx37. Cx37, Cx40 and Cx43 were also seen in the endothelium of arteries/arterioles outside of the glomeruli, whereas Cx45 was located in vascular smooth muscle cells. All four connexins were also expressed within the glomeruli. These findings indicate that the expression pattern of vascular connexins in the human kidney cortex is very similar to that previously found for mouse and rat kidneys, suggesting that the intrarenal expression pattern of vascular connexins is conserved among the mammalian species. Because of this similarity, and in particular in view of the strong expression of Cx37 and Cx40 in the juxtaglomerular area, we infer that those functions of connexins that have already been demonstrated for rodent kidneys, such as a central role of Cx40 for the development and function of renin-producing cells and for tubuloglomerular signal transmission, might hold for human kidneys as well.

Blockade of multiple but not single cytokines abrogates downregulation of angiotensin II type-I receptors and anticipates septic shock.

In this prospective, randomized animal study, the role of proinflammatory cytokines in the pathogenesis sepsis-induced circulatory failure with downregulation of angiotensin-II-type-I-(AT(1))-receptors was investigated. Sepsis in wild-type mice and in mice with deficiencies for TNF-alpha, IL-1beta, IFN-gamma or IL-6 was induced by cecal ligation and puncture (CLP) and wild-type mice were injected with cytokines. Animals were treated with glucocorticoids or small interfering RNA (siRNA) targeting single or multiple cytokines or NF-kappaB. Vascular smooth muscle cells (VSMCs) were incubated with cytokines. CLP resulted in circulatory failure and a significant downregulation of AT(1)-receptors. Injection of single proinflammatory cytokines also strongly downregulated AT(1)-receptors paralleled by a markedly endogenous liberation of further cytokines, whereas, simultaneous blockade of these endogenously activated cytokines by dexamethasone prevented downregulation of AT(1)-receptors. Furthermore, inhibition of multiple but not single cytokines by treatment with siRNA against multiple cytokines or NF-kappaB significantly attenuated CLP-induced AT(1)-receptor downregulation and prevented septic circulatory failure. Our data demonstrate that downregulation of AT(1)-receptors during sepsis is due to multiple but not single cytokines and define a relevant role for NF-kappaB in the pathogenesis of septic shock.

Inhibition of NF-kappaB ameliorates sepsis-induced downregulation of aquaporin-2/V2 receptor expression and acute renal failure in vivo.

Acute renal failure (ARF) is frequently associated with polyuria and urine concentration defects and it is a severe complication of sepsis because it increases the mortality rate. Inhibition of NF-kappaB activation has been suggested to provide a useful strategy for the treatment of septic shock. However, the impact on sepsis-induced ARF is still unclear. Therefore, we examined the effect of pyrrolidine dithiocarbamate (PDTC) and of small interfering RNA (siRNA) silencing NF-kappaB p50/p105 on sepsis-induced downregulation of vasopressin V(2) receptors and aquaporin (AQP)-2 channels using a cecal ligation and puncture (CLP) mouse model. CLP caused a time-dependent downregulation of renal vasopressin V(2) receptor and of AQP2 expression without alterations in plasma vasopressin levels. Renal activation of NF-kappaB in response to CLP was attenuated by PDTC pretreatment, which also attenuated the downregulation of V(2) receptor and AQP2 expression. Furthermore, a strong nuclear staining for the NF-kappaB p50 subunit throughout the whole kidney in response to CLP was observed. siRNA against NF-kappaB p50 attenuated the CLP-induced nuclear translocation of the p50 subunit and the CLP-induced downregulation of V(2) receptor and AQP2 expression. Additionally, PDTC and siRNA pretreatment inhibited the CLP-induced increase in renal TNF-alpha and IL-1beta concentration and NOS-2 mRNA abundance. Moreover, PDTC and siRNA pretreatment ameliorated CLP-induced hypotension and ARF. Our findings suggest that NF-kappaB activation is of importance for the downregulation of AQP2 channel and vasopressin V(2) receptor expression during sepsis. In addition, our data indicate that NF-kappaB inhibition ameliorates sepsis-induced ARF.