The role of cow's milk protein intolerance in steroid-resistant nephrotic syndrome

Effect of Combined Gluten-Free, Dairy-Free Diet in Children With Steroid-Resistant Nephrotic Syndrome: An Open Pilot Trial

Introduction

Steroid-resistant nephrotic syndrome (SRNS) affects both children and adults and has a high rate of progression to end-stage renal disease. Although a subset of patients have well-characterized genetic mutation(s), in the majority of cases, the etiology is unknown. Over the past 50 years, a number of case reports have suggested the potential impact of dietary changes in controlling primary nephrotic syndrome, especially gluten and dairy restrictions.

Methods

We have designed a prospective, open-label, nonrandomized, pilot clinical trial, to study the effect of a gluten-free and dairy-free (GF/DF) diet in children with SRNS. The study will be organized as a 4-week summer camp to implement a GF/DF diet in a tightly controlled and monitored setting. Blood, urine, and stool samples will be collected at different time points during the study.

Results

The primary end point is a reduction of more than 50% in the urine protein:creatinine ratio. The secondary end points include changes in urine protein, kidney function, and serum albumin, as well as effects in immune activation, kidney injury biomarkers, and gut microbiome composition and function (metagenomic/metatranscriptomic).

Conclusion

This study will advance the field by testing the effect of dietary changes in patients with SRNS in a highly controlled camp environment. In addition, we hope the results will help to identify a responder profile that may guide the design of a larger trial for further investigation.

Synaptopodin is upregulated by IL-13 in eosinophilic esophagitis and regulates esophageal epithelial cell motility and barrier integrity

Eosinophilic esophagitis (EoE) is an allergic inflammatory disease of the esophagus mediated by an IL-13-driven epithelial cell transcriptional program. Herein, we show that the cytoskeletal protein synaptopodin (SYNPO), previously associated with podocytes, is constitutively expressed in esophageal epithelium and induced during allergic inflammation. In addition, we show that the SYNPO gene is transcriptionally and epigenetically regulated by IL-13 in esophageal epithelial cells. SYNPO was expressed in the basal layer of homeostatic esophageal epithelium, colocalized with actin filaments, and expanded into the suprabasal epithelium in EoE patients, where expression was elevated 25-fold compared with control individuals. The expression level of SYNPO in esophageal biopsies correlated with esophageal eosinophil density and was improved following anti-IL-13 treatment in EoE patients. In esophageal epithelial cells, SYNPO gene silencing reduced epithelial motility in a wound healing model, whereas SYNPO overexpression impaired epithelial barrier integrity and reduced esophageal differentiation. Taken together, we demonstrate that SYNPO is induced by IL-13 in vitro and in vivo, is a nonredundant regulator of epithelial cell barrier function and motility, and is likely involved in EoE pathogenesis.

Pregnancy, Proteinuria, Plant-Based Supplemented Diets and Focal Segmental Glomerulosclerosis: A Report on Three Cases and Critical Appraisal of the Literature

Chronic kidney disease (CKD) is increasingly recognized in pregnant patients. Three characteristics are associated with a risk of preterm delivery or small for gestational age babies; kidney function reduction, hypertension, and proteinuria. In pregnancy, the anti-proteinuric agents (ACE-angiotensin converting enzyme-inhibitors or ARBS -angiotensin receptor blockers) have to be discontinued for their potential teratogenicity, and there is no validated approach to control proteinuria. Furthermore, proteinuria usually increases as an effect of therapeutic changes and pregnancy-induced hyperfiltration. Based on a favourable effect of low-protein diets on proteinuria and advanced CKD, our group developed a moderately protein-restricted vegan-vegetarian diet tsupplemented with ketoacids and aminoacids for pregnant patients. This report describes the results obtained in three pregnant patients with normal renal function, nephrotic or sub-nephrotic proteinuria, and biopsy proven diagnosis of focal segmental glomerulosclerosis, a renal lesion in which hyperfiltration is considered of pivotal importance (case 1: GFR (glomerular filtration rate): 103 mL/min; proteinuria 2.1 g/day; albumin 3.2 g/dL; case 2: GFR 86 mL/min, proteinuria 3.03 g/day, albumin 3.4 g/dL; case 3: GFR 142 mL/min, proteinuria 6.3 g/day, albumin 3.23 g/dL). The moderately restricted diet allowed a stabilisation of proteinuria in two cases and a decrease in one. No significant changes in serum creatinine and serum albumin were observed. The three babies were born at term (38 weeks + 3 days, female, weight 3180 g-62th centile; 38 weeks + 2 days, female, weight 3300 g-75th centile; male, 38 weeks + 1 day; 2770 g-8th centile), thus reassuring us of the safety of the diet. In summary, based on these three cases studies and a review of the literature, we suggest that a moderately protein-restricted, supplemented, plant-based diet might contribute to controlling proteinuria in pregnant CKD women with focal segmental glomerulosclerosis. However further studies are warranted to confirm the potential value of such a treatment strategy.

Nephrotic syndrome: what's new, what's hot?

While the incidence of nephrotic syndrome (NS) is decreasing in Korea, the morbidity of difficult-to-treat NS is significant. Efforts to minimize treatment toxicity showed that prolonged treatment after an initial treatment for 2-3 months with glucocorticosteroids was not effective in reducing frequent relapses. For steroid-dependent NS, rituximab, a monoclonal antibody against the CD20 antigen on B cells, was proven to be as effective, and short-term daily low-dose steroids during upper respiratory infections reduced relapses. Steroid resistance or congenital NS are indications for genetic study and renal biopsy, since the list of genes involved in NS is lengthening.

Effects of gluten-free, dairy-free diet on childhood nephrotic syndrome and gut microbiota

Emerging evidence suggests an association between food sensitivity and gut microbiota in children with nephrotic syndrome. Diminished proteinuria resulted from eliminating cow's milk and the use of an oligoantigenic diet which excluded gluten, especially in patients with immune-related conditions, i.e., celiac disease and nephrotic syndrome. The mechanisms underlying the association of diet, gut microbiota, and dysregulation of the immune system are unknown. Gut microbiota is influenced by a number of factors including diet composition and other environmental epigenetic exposures. The imbalance in gut microbiota may be ameliorated by gluten-free and dairy-free diets. Gluten-free diet increased the number of unhealthy bacteria while reducing bacterial-induced cytokine production of IL-10. Thus, gluten-free diet may influence the composition and immune function of gut microbiota and should be considered a possible environmental factor associated with immune-related disease, including nephrotic syndrome. Furthermore, the imbalance of gut microbiota may be related to the development of cow's milk protein allergy. Investigations are needed to fill the gaps in our knowledge concerning the associations between the gut microbiome, environmental exposures, epigenetics, racial influences, and the propensity for immune dysregulation with its inherent risk to the developing individual.

Idiopathic nephrotic syndrome and atopy: is there a common link?

Numerous reports during the last 60 years have reported a strong association between idiopathic nephrotic syndrome and atopic disorders. Idiopathic nephrotic syndrome can be precipitated by allergic reactions and has been associated with both aeroallergens (pollens, mold, and dust) and food allergies. Patients with idiopathic nephrotic syndrome also may show increased serum immunoglobulin E (IgE) levels. A review of the literature suggests that although some idiopathic nephrotic syndrome cases may be associated with allergies, evidence that it is a type of allergic disorder or can be induced by a specific allergen is weak. Rather, it is likely that the proteinuria and increased IgE levels in patients with idiopathic nephrotic syndrome are caused by increased levels of interleukin 13 observed in these patients. Recent studies suggest that interleukin 13, a known stimulator of IgE response, may mediate proteinuria in patients with minimal change disease because of its ability to directly induce CD80 expression on the podocyte.

Clinical expressions of food allergy

BACKGROUND

The perception, by both the public and health professionals, of the clinical expressions of food allergy (FA) varies widely, from one extreme of nonexistence to another extreme of causing almost every ailment. Critical investigations in recent years led to a better clarification, as well as a reasonable classification, of FA manifestations.

OBJECTIVE

To provide a differential diagnosis of adverse reactions to foods and a classification of well proven FA manifestations.

DATA SOURCES

Reviews and original articles published in peer-reviewed journals, as well as classic textbooks on FA.

RESULTS

FA can affect several body systems. The gastro-intestinal tract is probably the most affected organ, but it does not always exhibit overt symptoms. Cutaneous manifestations are next in frequency, and in some studies are the most frequent perhaps because they are visible. Respiratory symptoms as sole manifestations of FA are less common, but have high frequency in children with atopic dermatitis. Systemic anaphylaxis has been responsible for sudden fatalities, although the exposure was often to minute quantities of the offending food. Other rare manifestations have been reported and are probably underdiagnosed.

CONCLUSIONS

FA is defined as the immunologically mediated adverse reactions to foods. It can be expressed in a wide array of clinical manifestations, ranging from simple gastro-intestinal, cutaneous, or respiratory symptoms to fatal anaphylaxis. Studies are needed to verify some rare or anecdotal manifestations that have been reported but are still considered controversial.

Unusual presentations of food allergy

OBJECTIVE

This presentation is designed to critically review information on presentations of food hypersensitivity reactions that may be considered unusual regarding the source or nature of allergen, route of exposure, or clinical manifestation.

DATA SOURCES

Information has been gathered primarily through a thorough search of the English literature relevant to human subjects. Some clinical cases were also included from the author's own clinical experience.

STUDY SELECTION

Information summarized here was critically selected on the basis of proven or acceptable scientific validity.

RESULTS

The findings indicate that food allergy presentation can be unusual in three main aspects. First, the offending allergen may not be the obvious food that was ingested or be a food protein incorporated in a nonfood product. Second, systemic reactions can be provoked by very minute quantities of food allergens that may even get access through noningestant routes, eg, inhalation, odor, skin contact, or mucous membrane contact. Third, the clinical manifestations are not limited to the few gastrointestinal, cutaneous, and respiratory symptoms with which we are generally familiar.

CONCLUSIONS

The extent of food allergy presentation is more than has been generally realized. Our awareness of such unusual presentations adds new knowledge and should prompt our interest in carefully evaluating patients with obscure allergic reactions for possible food allergy.

Evaluation of intestinal permeability and gluten sensitivity in Soft-Coated Wheaten Terriers with familial protein-losing enteropathy, protein-losing nephropathy, or both

OBJECTIVE

To evaluate intestinal permeability and gluten sensitivity in a family of Soft-Coated Wheaten Terriers (SCWT) affected with protein-losing enteropathy (PLE), protein-losing nephropathy (PLN), or both.

ANIMALS

6 affected adult dogs.

PROCEDURE

Intestinal biopsy specimens, urine protein-to-creatinine ratio, serum concentrations of albumin and globulin, and concentration of alpha1-protease inhibitor in feces were evaluated before, during, and 13 weeks after daily administration of 10 g of gluten for 7 weeks. Eosinophils and lymphocytes-plasmacytes were enumerated in intestinal biopsy specimens. Intestinal permeability was evaluated before and during the sixth week of gluten administration via cellobiose-mannitol and chromium-EDTA absorption tests.

RESULTS

Serum globulin concentration decreased significantly after prolonged administration of gluten. Although not significant, there was an increase in lymphocytes-plasmacytes and a decrease in eosinophils in intestinal biopsy specimens. Furthermore, these counts were greater than those reported for clinically normal dogs. Gluten administration did not increase intestinal permeability.

CONCLUSIONS AND CLINICAL RELEVANCE

Daily administration of gluten was associated with a significant decrease in serum globulin concentration in SCWT affected with PLE or PLN, but other variables remained unchanged. Although enhanced wheat-gluten sensitivity may be one factor involved in the pathogenesis of PLE or PLN in SCWT, this syndrome does not appear to be the result of a specific sensitivity to gluten.

Treatment of nephrotic adults with a supplemented, very low-protein diet

Optimal dietary protein intake for adults with the nephrotic syndrome has not been established; very low-protein diets are believed to be contraindicated. Sixteen patients with the nephrotic syndrome were nevertheless prescribed a very low protein diet (0.3 g/kg) supplemented by 10 to 20 g/d essential amino acids (or, in a few cases, ketoacids) for an average of 10 months (range, 1 to 36 months). In 11 patients with initial glomerular filtration rates (GFRs) < or = 30 mL/min/3 m2 of height (ht)2, significant but modest improvement was seen (on the average) in proteinuria, serum albumin, and serum cholesterol; all 11 eventually went on to dialysis. The other five patients, with initial GFRs of 32 to 69 ml/min/3 m2 of ht2, had either focal segmental glomerulosclerosis, diabetic nephropathy, or, in one patient, both. The nephrotic syndrome associated with these disorders rarely remits spontaneously. However, during the following 3 to 15 months mean proteinuria decreased from 9.3 to 1.9 g/d, mean serum albumin increased from 2.5 g/dL to 3.8 g/dL, and mean serum cholesterol decreased from 415 mg/dL to 255 mg/dL (all P < 0.001). The GFR either remained constant or increased. Four of these five patients have resumed normal or nearly normal diets and remain in remission or near-remission for 6 to 24 months. We conclude that severe protein restriction plus an essential amino acid supplement may induce prolonged remission in adults with the nephrotic syndrome provided that GFR is not severely reduced. The mechanism of this paradoxical response to protein restriction remains to be determined.