When does infrastructure hybridisation outperform centralised infrastructure paradigms? - Exploring economic and hydraulic impacts of decentralised urban wastewater system expansion

We explore the dynamics of centralised and decentralised wastewater infrastructure across various scenarios and introduce novel insights into their performance regarding structural vulnerability, hydraulic capacity, and costs. This study determines circumstances under which infrastructure hybridisation outperforms traditional centralised infrastructure paradigms. We combined system analysis to map out the modelling problem with the model-based exploration of the transition space using the novel TURN-Sewers model. System diagramming was used to identify the parameters or combinations of parameters that significantly influence the performance indicators being assessed. This allowed the creation of relevant simulation scenarios to identify circumstances where a decentralised sewer system could outperform a centralised one. TURN-Sewers was applied to model the infrastructure maintenance and generation of new infrastructure over 20 years for a municipality on the Swiss Plateau, considering a population growth rate of 0.03 a-1. Results show that decentralisation in expansion areas with higher densification can outperform the hydraulic performance and structural vulnerability of expanding centralised sanitary wastewater infrastructure. Decentralised systems can also offer economic advantages when capital expenditure costs for small-scale wastewater treatment plants are significantly reduced compared to current costs, particularly at higher discount rates, e.g. reaping effects of economies of scale. The findings of this study emphasise the potential of transition pathways towards decentralisation in urban water infrastructures and the value of models that allow the exploration of this transition space.

The Burden of Suboptimal Insulin Dosing in People with Diabetes in Spain: Barriers and Solutions from the Physician Perspective

Background

This study aimed to determine physicians' perceptions of the extent of suboptimal insulin dosing and the barriers and solutions to optimal dosing in people with diabetes (PwD) treated with insulin.

Methods

A cross-sectional online survey was conducted in four countries with primary care physicians and endocrinologists treating PwD using insulin pens, which included 53 questions on physicians' characteristics and their perceptions of the behaviors of PwD in relation to insulin dosing routines, unmet needs and potential solutions. Analyses were descriptive.

Results

Of the 160 physicians (80 primary care physicians, 80 specialists) surveyed in Spain, 58.1% were male and 88.8% had been qualified to practice for more than five years. Most physicians (>65%) indicated that 0-30% of PwD missed or skipped, mistimed, or miscalculated an insulin dose in the last 30 days. Common reasons for these actions were that PwD forgot, were out of their normal routine, were too busy or distracted, or were unsure of how much insulin to take. To optimize insulin dosing, over 75% of physicians considered it very helpful for PwD to have real-time insulin dosing calculation guidance, mobile app reminders, a device automatically recording glucose measurements and/or insulin, having insulin and glucose data in one place, and having the time for more meaningful conversations about insulin dosing routines.

Conclusion

According to physicians' perspectives, suboptimal insulin dosing remains common among PwD. This survey highlights the need for integrated and automated insulin dosing support to manage the complexity of insulin treatment, improve communications between PwD and physicians, and ultimately improve outcomes for PwD.

Which people with diabetes are treated with a disposable, half-unit insulin pen? A real-world, retrospective, database study in Spain

INTRODUCTION

Insulin lispro 100 units/mL Jr KwikPen is the first prefilled, disposable, half-unit insulin pen that delivers 0.5-30 units in increments of 0.5 units for the treatment of patients with diabetes. This study describes the profile of patients in Spain who initiated insulin therapy with Jr KwikPen in a real-world setting.

METHODS

This retrospective, observational study based on IQVIA's electronic medical records database included patients with Type 1 (T1D) or Type 2 (T2D) diabetes who initiated therapy with Jr KwikPen between May 2018 and December 2020. Sociodemographic, clinical, and treatment characteristics at treatment initiation were analysed descriptively.

RESULTS

A total of 416 patients were included. The main characteristics of the T1D/T2D groups (N = 326/90), respectively were as follows: female sex, 61.7%/65.6%; mean age (standard deviation [SD]), 32.5 (20.7)/55.5 (16.6) years; body mass index, 20.9 (4.2)/25.2 (4.6) kg/m2 (N = 239/77); HbA1c, 7.8 (1.7)%/8.0 (1.5)% (N = 141/64); and presence of diabetes-associated comorbidities, 27.9%/64.4%. Only 32.8% of patients with T1D were < 18 years old. Among Jr KwikPen users, 12.3% (T1D/T2D, 7.7%/28.9%) were ≥ 65 years old, 17.1% patients were newly diagnosed, and 3.8% were pregnant women. The mean (SD) total insulin dose pre-index for T1D/T2D was 43.1 (23.6) and 40.7 (21.6) UI/day, respectively. The mean (SD) insulin dose at the start of Jr KwikPen use was 26.63 (16.56) and 22.58 (13.59) UI/day for T1D/T2D, respectively. Jr KwikPen was first prescribed mainly by endocrinologists (58.7%) or paediatricians (22.6%).

CONCLUSIONS

The profile of patients who initiated therapy with Jr KwikPen in routine practice was broad with many patients being adults. Most of these patients had T1D, inadequate glycemic control, and multiple associated comorbidities. These results suggest that Jr KwikPen is prescribed in patients who may benefit from finer insulin dose adjustments, namely children, adolescents, adults, older individuals, or pregnant women with T1D or T2D.

Profile of Patients with Diabetes Treated with Insulin Lispro 200 U/ml: A Real-World Study from Spain

INTRODUCTION

Insulin lispro 200 U/ml (IL200) is a rapid-acting concentrated insulin used for the treatment of adults with diabetes requiring daily doses of > 20 units of rapid-acting insulin. The aim of this study was to describe the clinical/demographic and treatment characteristics of patients who initiated insulin IL200 therapy in Spain in a real-world setting (PROFILE-IL200).

METHODS

This retrospective observational study based on the IQVIA database included adult (≥ 18 years) patients with type 1 (T1D) or type 2 (T2D) diabetes who initiated IL200 between June 2015 and December 2019. Demographic and clinical characteristics were analyzed descriptively.

RESULTS

Main characteristics for the T1D/T2D groups (N = 65/167) were as follows: male, 63.1/55.7%; mean (standard deviation [SD]) age, 46.5 (15.5)/62.6 (12.8) years; time since first diabetes record, 6.6 (4.2)/7.9 (2.9) years; body mass index (BMI), 30.9 (5.8)/33.1 (5.5) kg/m²; glycated hemoglobin, 8.3 (2.1)/8.8 (1.8)%; and diabetes-associated comorbidity, 55.4/92.8%. Among patients with T1D/T2D and a prior diagnosis (N = 54/164), 96.3/90.2% had received previous insulin (rapid insulin in 81.5/62.2%), and 13.0/97.6% had received previous noninsulin antihyperglycemic therapy. The mean (SD) total insulin dose before IL200 initiation for T1D/T2D was 98.0 (73.9)/95.2 (59.8) U/day; IL200 was initiated at a dose of 56.3 (43.8)/51.5 (34.3) U/day, with basal insulin in 86.2/83.2% of the patients. IL200 was first prescribed by an endocrinologist or a primary care physician in 48.7% and 46.6% of patients, respectively.

CONCLUSIONS

PROFILE-IL200 described the profile of patients treated with IL200 in clinical practice in Spain. Patients were middle-aged, with poor glycemic control, high BMI and associated comorbidities, and received high doses of insulin at IL200 initiation.

A Simplified Sanitary Sewer System Generator for Exploratory Modelling at City-Scale

Future climatic, demographic, technological, urban and socio-economic challenges call for more flexible and sustainable wastewater infrastructure systems. Exploratory modelling can help to investigate the consequences of these developments on the infrastructure. In order to explore large numbers of adaptation strategies, we need to re-balance the degree of realism of sewer network and ability to reflect key performance characteristics against the model's parsimony and computational efficiency. We present a spatially explicit algorithm for creating sanitary sewer networks that realistically represent key characteristics of a real system. Basic topographic, demographic and urban characteristics are abstracted into a squared grid of 'Blocks' which are the foundation for the sewer network's topology delineation. We compare three different pipe dimensioning approaches and found a good balance between detail and computational efficiency. With a basic hydraulic performance assessment, we demonstrate that we attain a computationally efficient and high-fidelity wastewater sewer network with adequate hydraulic performance. A spatial resolution of 250 m Block size in combination with a sequential Pipe-by-Pipe (PBP) design algorithm provides a sound trade-off between computational time and fidelity of relevant structural and hydraulic properties for exploratory modelling. We can generate a simplified sewer network (both topology and hydraulic design) in 18 s using PBP, versus 36 min using a highly detailed model or 1 s using a highly abstract model. Moreover, this simplification can cut up to 1/10th to 1/50th the computational time for the hydraulic simulations depending on the routing method implemented. We anticipate our model to be a starting point for sophisticated exploratory modelling into possible infrastructure adaptation measures of topological and loading changes of sewer systems for long-term planning.

New PAX2 Mutation Associated with Polycystic Kidney Disease: A Case Report

BACKGROUND

Congenital anomalies of the kidney and urinary tract (CAKUT) are the leading cause of end stage renal disease in children. Diagnosis by genetic testing has proven challenging due to its genetic and phenotypic heterogeneity, as well as incomplete penetrance. We report a case on a 16-months old female with a history of renal cysts and a PAX2 mutation.

CASE PRESENTATION

The patient presented with a prenatal diagnosis of Potter sequence and a postnatal diagnosis of renal cysts. An ultrasound at 20 weeks gestation revealed right renal agenesis and possible left renal dysplasia. Post natal genetic analyses identified a novel mutation in PAX2.

CONCLUSION

Cystic kidney disease is often underdiagnosed due to its variable expressivity and wide range of clinical manifestations; PAX2 genetic screening should be considered for all patients with CAKUT.

Nefropatía por inmunoglobulina A en pediatría, desenlaces clínicos con diferentes esquemas de manejo

Introducción:la nefropatía por inmunoglobulina A (NIgA) es la enfermedad glomerular más común en el mundo. En Colombia, el 11-22 % de las glomerulonefritis primarias en niños corresponden a NIgA y de estos casos, el 30 % progresa a enfermedad renal terminal. Objetivo: describir las características paraclínicas e histopatológicas de la NIgA, así como los resultados clínicos según tres tipos de tratamiento en pacientes pediátricos con esta enfermedad atendidos en un hospital de alta complejidad del suroccidente colombiano. Materiales y métodos: estudio retrospectivo realizado en pacientes pediátricos de entre 1 mes y 18 años de edad con diagnóstico de NIgA. Las variables categóricas se presentaron como proporciones y las continuas con medianas y rango intercuartílico. Se usó la prueba de Fisher para comparar los tres esquemas de tratamiento. Resultados:se incluyeron 58 pacientes pediátricos atendidos entre 1996 y 2013. La media de edad al inicio de síntomas fue 7,5±4,2 años y al momento de la biopsia renal, 10±3,8 años. El 77,6 % de los pacientes presentó hematuria microscópica y el 27,6 %, macroscópica. Además, el Histológicamente, el 10 % se clasificó como grado I, el 62 % como grado II, el 21 % como grado III y el 7 % como grado IV. Tres pacientes requirieron diálisis 81 % tuvo proteinuria, siendo severa el 29 %. y dos, trasplante renal. Los esquemas terapéuticos evaluados fueron: solo prednisona (n=20, 34,5 %), prednisona y mofetil micofenolato (MMF) (n=13, 22,4 %) y sin prednisona ni MMF (n=25, 43,1 %). La diferencia en la presencia de hematuria entre los grupos fue significativa (p>0,001), siendo más frecuente en el grupo sin prednisona ni MMF (68 %). No hubo diferencia entre los grupos de proteinuria, hipertensión arterial y valor de creatinina. La mediana de años entre la biopsia renal y el ultimo control fue de 4 años (RIC 1-7). La supervivencia de la función renal fue del 89,1 % a los 5 años. Conclusión:la NIgA amerita reconocimiento temprano y seguimiento estricto, ya que puede tener desenlaces ominosos como enfermedad renal crónica.  

Review of the renal endpoints used in cardiovascular safety clinical trials in type 2 diabetes mellitus patients and their importance in primary care

Chronic kidney disease (CKD) is one of the most common complications of type 2 diabetes mellitus (T2DM). Furthermore, CKD confers a considerable increase in the risk of cardiovascular (CV) morbidity and mortality. In line with the need to improve knowledge in this field, this article aims to describe the renal endpoints used in the different cardiovascular outcome trials (CVOTs). The objective is to better know the renal variables used in the different CVOTs in order to optimize the implementation of advances in the prevention of progressive diabetic kidney disease in patients with T2DM in clinical practice.

Managing the open abdomen: negative pressure closure versus mesh-mediated fascial traction closure: a randomized trial

PURPOSE

To compare the effectiveness of abdominal wall closure using the vacuum-assisted closure (NPC) as described by Barker et al. with an institutional protocol using a double polyvinyl bag in the first surgery, which is changed in subsequent surgeries to a polyvinyl bag placed over the bowel loops and a prolene mesh attached to the abdominal fascia (MMFC).

METHODS

Randomized controlled trial. Patients with open abdomen (OA) due to a traumatic or a medical cause were included in the study. Variables studied included demographics, indication for surgery, number of interventions, hospital length of stay (HLOS), ICU length of stay, abdominal wound care costs, complication rates, and method and time to definitive fascial closure.

RESULTS

From June 2011 to April 2013, 75 patients were enrolled in the study. Patients who died within 48 h were excluded; therefore, 53 patients in total were assessed. NPC achieved fascial closure in 75% of patients, and MMFC achieved closure in 71.9% of patients. The closure rates in patients with OA secondary to medical causes (80% by NPC vs. 71.4% by MMFC) or traumatic causes (70% by NPC vs. 73.7% by MMFC) were similar in both treatment groups. There were no differences between the groups with respect to cause of OA, complications, length of hospital stay, or the length of stay in the intensive care unit.

CONCLUSION

MMFC is a method comparable to NPC for the temporary management of OA that results in similar closure and complication rates.

Visualization and clustering of sleep states in a frequency domain feature space

Sleep studies assess the recurrent manifestation of stereotype configurations of relevant biosignals. These configurations are known as states (Wake, REM sleep and NonREM sleep) and stages (N1-N3 within NREM sleep). These two fundamental descriptive domains, time course and variable configuration, can be readily rendered available through improved visualization techniques. Time course is summarized by EEG spectrograms, instantaneous frequency analysis of cardio-respiratory signals and other sleep dependent variables. State and stage configurations can be further evidenced as clusters in 2D or 3D spaces whose axis are sleep-relevant extracted variables. The latter techniques also allows for visualization of transition process as pathways from one cluster to another.

Proapoptotic Fas ligand is expressed by normal kidney tubular epithelium and injured glomeruli

Fas ligand (FasL) is a cell membrane cytokine that can promote apoptosis through activation of Fas receptors. Fas receptor activation induces glomerular cell apoptosis in vivo and participates in tubular cell death during acute renal failure. However, there is little information on the expression of FasL in the kidney. This study reports that FasL mRNA and protein are present in normal mouse and rat kidney. In situ hybridization and immunohistochemistry showed that proximal tubular epithelium is the main site of FasL expression in the normal kidney. In addition, increased total kidney FasL mRNA and de novo FasL protein expression by glomerular cells were observed in two different models of glomerular injury : rat immune-complex proliferative glumerulonephritis and murine lupus nephritis. Both full-length and soluble FasL were increased in the kidneys of the mice with nephritis. Cultured murine proximal tubular epithelial MCT cells and primary cultures of murine tubular epithelial cells expressed FasL mRNA and protein. Tubular epithelium-derived FasL induced apoptosis in Fassensitive lymphoid cell lines but not in Fas-resistant lymphoid cell lines. By contrast, MCT cells grown in the presence of the survival factors of serum were resistant to FasL, and only became partially sensitive to apoptosis induced by high concentrations (100 ng/ml) of FasL upon serum deprivation. However, MCT cells stimulated with inflammatory mediators (tumor necrosis factor-alpha, interferon-gamma, and lipopolysaccharide) increased cell surface Fas expression and were sensitized to apoptosis induced by FasL (FasL 55 +/- 5% versus control 8.3 +/- 4.1% apoptotic cells at 24 h, P < 0.05). Cytokine-primed primary cultures of tubular epithelial cells also acquired sensitivity to FasL-induced apoptosis. These results suggest that FasL expression by intrinsic renal cells may play a role in cell homeostasis in the normal kidney and during renal injury.

Administration of IgG Fc fragments prevents glomerular injury in experimental immune complex nephritis

Most human nephritis is due to glomerular deposition and/or formation of immune complexes (IC). In cultured mesangial cells, Fc receptor stimulation induces proliferation, matrix synthesis, and release of several mediators implicated in the initiation and progression of glomerular injury. Since Ig Fc fragments in vitro modified these phenomena, we studied the effects of systemic administration of IgG Fc fragments on the evolution of experimental IC nephritis. Fc fragment injection (1 mg/day i.p.) to rats with ongoing nephritis (proteinuria 20-50 mg/24 h vs 9 +/- 0.2 mg/24 h in controls) markedly ameliorates proteinuria, renal function, and morphological renal lesions. This was accompanied by a reduction in the renal synthesis of chemokines (monocyte chemoattractant protein-1, IFN-inducible protein-10, and cytokine-induced neutrophil chemoattractant-1), matrix proteins, and growth factors (platelet-derived growth factor, and TGF-beta), and in the activity of transcription factors. The treatment did not affect the glomerular deposition of IgG IC and complement C1q. In contrast, a decrease in the renal expression and production of C3 was observed without changes in serum complement levels. In vitro, very low complement consumption and no C3b covalent interaction were observed with Fc fragments, confirming that they did not modify systemic complement activity. These results indicate that the administration of Fc fragments prevents the development of glomerular damage in an aggressive model of proliferative glomerulonephritis through mechanisms involving a reduced local generation of complement, chemokines and growth factors. Modulation of IC-mesangial cell interaction by Fc fragment administration could represent a new approach to the treatment of severe immune nephritis.

Long-term protective effect of UR-12670 after warm renal ischemia in uninephrectomized rats

BACKGROUND

The phospholipid platelet-activating factor (PAF) participates in the pathogenesis of renal ischemia/reperfusion injury, and in vitro, it induces synthesis of extracellular matrix proteins by mesangial and tubular epithelial cells. This study investigated the long-term effects of the potent orally active PAF antagonist UR-12670 in warm ischemic uninephrectomized rats, which was given according to different therapeutic schedules.

METHODS

Uninephrectomized male Sprague-Dawley rats were divided into five groups and were followed for 52 weeks: rats without ischemia (SK); ischemic kidney for 60 minutes (SIK); ischemic kidney and UR-12670 from 0 to the 7th day (UR 0-7); ischemic kidney and UR-12670 from day 0 to 52 weeks (UR 0-E); and ischemic kidney and UR-12670 from day 8 to week 52 (UR 8-E). Two more groups (ischemic and UR treated) served to evaluate the UR-12670-protective effect on ischemic acute renal failure at one week.

RESULTS

UR-12670 administration exerted functional and morphological protection against post-ischemic acute renal failure. The ischemic untreated (SIK) group developed progressive proteinuria from week 12. The onset of proteinuria in ischemic UR-12670-treated groups was delayed to the 24th week, and it was significantly lower than in SIK group throughout the study. Only SIK and ischemic-treated UR 0-7 rats presented with chronic renal failure, as shown by creatinine, creatinine clearance, glomerular filtration rate (GFR), and renal plasma flow (GFR 52 weeks: SK, 2525 +/- 267; SIK, 992 +/- 149; UR 0-7, 1551 +/- 385 microliter/min). Kidneys from the short-term treated group (UR 0-7) showed a reduction of glomerulosclerosis (SK, 14.4 +/- 3.7; SIK, 75.7 +/- 7.7; UR 0-7, 41. 5 +/- 8.5%) and vascular myointimal hyperplasia, but the tubulointerstitial damage (tubulointerstitial score: SK, 0.2 +/- 0. 2; SIK, 4.4 +/- 0.5; UR 0-7, 3.7 +/- 0.7) was similar to that in the ischemic untreated group. Long-term ischemic treated rats (UR 0-E, UR 8-E) did not develop chronic renal failure (GFR: UR 0-E, 2059 +/- 314; UR 8-E, 2410 +/- 208 microliter/min). In these groups, glomerulosclerosis (UR 0-E, 32.8 +/- 5.8; UR 8-E, 24.3 +/- 3.0%), tubulointerstitial damage (tubulointerstitial score: UR 0-E, 2.1 +/- 0.5; UR 8-E, 1.9 +/- 0.3) and vascular myointimal hyperplasia were significantly lower than in the ischemic untreated group. By in situ hybridization, an increase of transforming growth factor-beta1 mRNA expression in glomerular and tubular cells was observed in ischemic untreated and ischemic treated UR 0-7 rats. UR-12670 long-term treated rats showed a clear reduction of transforming growth factor-beta1 mRNA-positive glomerular cells.

CONCLUSION

The chronic administration of the PAF antagonist UR-12670 attenuates the long-term effects of ischemia-reperfusion injury in uninephrectomized rats. The beneficial effect of this agent, even when given beyond the initial ischemia/reperfusion injury, suggests that PAF plays a role in the mechanisms of progression to late renal damage in this model.

Mesangial cells possess an asialoglycoprotein receptor with affinity for human immunoglobulin A

Asialoglycoprotein receptor (ASGP-R), a hepatic lectin involved in the clearance of galactose-terminal glycoproteins, is also present in extrahepatic tissues, but its expression in renal cells is not well established. This study examines the presence of ASGP-R in cultured mesangial cells (MC), key cells involved in the removal of macromolecules deposited in the glomerulus. The binding of asialo-orosomucoid (ASOR) to rat MC was saturable and galactose-specific. In addition, MC internalized and degraded ASOR in a Ca(2+)-dependent manner. Parallel studies were performed in a homologous system (human MC), obtaining similar binding curve and competition with unlabeled ASOR and carbohydrates. The purified receptor from rat MC consisted of two proteins (41 and 55 kD) with similar size to the hepatic receptor. Both subunits were detected by mRNA expression analysis (ratio 2:1). Because the hepatic receptor presents avidity for the carbohydrates of IgA1, a protein deposited in the glomerulus of patients with IgA nephropathy, the interaction of IgA1 with the mesangial ASGP-R was explored. As for the interaction with ASOR, catabolism of IgA1 by rat and human MC was Ca(2+)-dependent and was reduced with galactose. In addition, the interaction of ASOR with rat MC was partially inhibited by incubation with IgA1 and its desialylated form, but not by IgA2, as demonstrated in binding experiments and in receptor purification. It is concluded that MC possess ASGP-R specific for galactose residues of several glycoproteins, including IgA1. These data could be important for a better understanding of the pathogenesis of IgA nephropathy.

Interaction of IgA with Fc alpha receptors of human mesangial cells activates transcription factor nuclear factor-kappa B and induces expression and synthesis of monocyte chemoattractant protein-1, IL-8, and IFN-inducible protein 10

The mechanisms of glomerular damage in IgA nephropathy remain undefined. Mesangial cells (MC) possess Fc receptors for IgA (Fc alpha R), and their occupancy triggers cytokine expression, cell proliferation, and extracellular matrix synthesis. In cultured human MC we examined the effects of soluble IgA aggregates (AIgA) on the activation of nuclear factor-kappa B (NF-kappa B) and the production of proinflammatory chemokines monocyte chemoattractant protein-1 (MCP-1), IL-8, and IFN-inducible protein-10 (IP-10). The exposure of MC to AIgA rapidly activated a NF-kappa B complex constituted of p50 and p65 subunits. NF-kappa B activation was dose dependent, abolished by preincubation with IgA Fc fragments (indicating that AIgA effects occur via specific Fc alpha R), and attenuated by kinase inhibitors. MC stimulation with AIgA increased the mRNA expression of MCP-1, IL-8, and IP-10 in a time- and dose-dependent manner. Maximal expression of IL-8 was observed at 3 h (4.5-fold), while IP-10 and MCP-1 peaked at 6 h (5-fold for both). AIgA also induced biosynthesis and release of the chemokines, which presented biological activity in neutrophil and monocyte chemoattractant assays, peaking at 6 and 9 h, respectively. MC pretreatment with the antioxidant pyrrolidine dithiocarbamate inhibited NF-kappa B activation and chemokine mRNA expression. This study shows that stimulation of Fc alphaR in MC induces gene expression of MCP-1, IL-8, and IP-10, a process partially mediated by NF-kappa B activation. These data may be of importance for a better understanding of the pathogenesis of glomerular damage in IgA immune complex-related diseases.

Interaction of IgA with Fc alpha receptors of human mesangial cells activates transcription factor nuclear factor-kappa B and induces expression and synthesis of monocyte chemoattractant protein-1, IL-8, and IFN-inducible protein 10

The mechanisms of glomerular damage in IgA nephropathy remain undefined. Mesangial cells (MC) possess Fc receptors for IgA (Fc alpha R), and their occupancy triggers cytokine expression, cell proliferation, and extracellular matrix synthesis. In cultured human MC we examined the effects of soluble IgA aggregates (AIgA) on the activation of nuclear factor-kappa B (NF-kappa B) and the production of proinflammatory chemokines monocyte chemoattractant protein-1 (MCP-1), IL-8, and IFN-inducible protein-10 (IP-10). The exposure of MC to AIgA rapidly activated a NF-kappa B complex constituted of p50 and p65 subunits. NF-kappa B activation was dose dependent, abolished by preincubation with IgA Fc fragments (indicating that AIgA effects occur via specific Fc alpha R), and attenuated by kinase inhibitors. MC stimulation with AIgA increased the mRNA expression of MCP-1, IL-8, and IP-10 in a time- and dose-dependent manner. Maximal expression of IL-8 was observed at 3 h (4.5-fold), while IP-10 and MCP-1 peaked at 6 h (5-fold for both). AIgA also induced biosynthesis and release of the chemokines, which presented biological activity in neutrophil and monocyte chemoattractant assays, peaking at 6 and 9 h, respectively. MC pretreatment with the antioxidant pyrrolidine dithiocarbamate inhibited NF-kappa B activation and chemokine mRNA expression. This study shows that stimulation of Fc alphaR in MC induces gene expression of MCP-1, IL-8, and IP-10, a process partially mediated by NF-kappa B activation. These data may be of importance for a better understanding of the pathogenesis of glomerular damage in IgA immune complex-related diseases.

Stimulation of Fc(alpha) receptors induces tyrosine phosphorylation of phospholipase C-gamma(1), phosphatidylinositol phosphate hydrolysis, and Ca2+ mobilization in rat and human mesangial cells

Although knowledge of IgA Fc receptor (Fc(alpha)R) structure and gene organization has progressed in the past few years, signal transduction pathways elicited by its activation have hardly been studied. Previously, we have demonstrated that mesangial cells (MC) possess Fc(alpha)R stimulation triggers several biologic responses. In this work, we studied the early biochemical signals triggered by Fc(alpha)R stimulation in MC. MC incubation with aggregated IgA (AIgA) elicited a dose-dependent increase in cytosolic Ca2+ ([Ca2+]i). The response was rapid and transient, and slowly fell to the original baseline. Ca2+ mobilization was dependent on the Fc region of the IgA, because Fc, but neither Fab fragment nor carbohydrates, inhibited the [Ca2+] rise. The initial induction of [Ca2+]i rise was due to Ca2+ mobilization from inositol trisphosphate (IP3)-sensitive intracellular stores, while sustained levels were maintained through extracellular Ca2+ influx. Stimulation of Fc(alpha)R also resulted in production of IP3, temporally correlated with Ca2+ mobilization. Protein tyrosine kinase inhibitors abolished [Ca2+]i rise, indicating that tyrosine phosphorylation of some substrates is required for Ca2+ mobilization. Stimulation through Fc(alpha)R gave rise to a marked increase in tyrosine phosphorylation of several proteins, including the 147-kDa band, similar in size to phospholipase C-gamma(1) (PLC-gamma(1)). Tyrosine phosphorylation of PLC-gamma(1) reached a maximum 30 s after stimulation, as determined by immunoprecipitation and Western blot. Collectively, these results indicate that the Fc(alpha)R signaling pathway in MC involves PLC-(gamma(1) activation, IP3 formation, and Ca2+ mobilization, and is linked to activation of tyrosine kinases.

Stimulation of Fc(alpha) receptors induces tyrosine phosphorylation of phospholipase C-gamma(1), phosphatidylinositol phosphate hydrolysis, and Ca2+ mobilization in rat and human mesangial cells

Although knowledge of IgA Fc receptor (Fc(alpha)R) structure and gene organization has progressed in the past few years, signal transduction pathways elicited by its activation have hardly been studied. Previously, we have demonstrated that mesangial cells (MC) possess Fc(alpha)R stimulation triggers several biologic responses. In this work, we studied the early biochemical signals triggered by Fc(alpha)R stimulation in MC. MC incubation with aggregated IgA (AIgA) elicited a dose-dependent increase in cytosolic Ca2+ ([Ca2+]i). The response was rapid and transient, and slowly fell to the original baseline. Ca2+ mobilization was dependent on the Fc region of the IgA, because Fc, but neither Fab fragment nor carbohydrates, inhibited the [Ca2+] rise. The initial induction of [Ca2+]i rise was due to Ca2+ mobilization from inositol trisphosphate (IP3)-sensitive intracellular stores, while sustained levels were maintained through extracellular Ca2+ influx. Stimulation of Fc(alpha)R also resulted in production of IP3, temporally correlated with Ca2+ mobilization. Protein tyrosine kinase inhibitors abolished [Ca2+]i rise, indicating that tyrosine phosphorylation of some substrates is required for Ca2+ mobilization. Stimulation through Fc(alpha)R gave rise to a marked increase in tyrosine phosphorylation of several proteins, including the 147-kDa band, similar in size to phospholipase C-gamma(1) (PLC-gamma(1)). Tyrosine phosphorylation of PLC-gamma(1) reached a maximum 30 s after stimulation, as determined by immunoprecipitation and Western blot. Collectively, these results indicate that the Fc(alpha)R signaling pathway in MC involves PLC-(gamma(1) activation, IP3 formation, and Ca2+ mobilization, and is linked to activation of tyrosine kinases.