Polymorphism of bovine beta-casein and its potential effect on human health

Milk protein polymorphisms and casein haplotypes in Butana cattle

Butana is a Bos indicus dairy cattle breed that is well adapted to the local environment of Sudan. The breed has been gradually declining in number due to breed substitution. Therefore, conservation and improvement strategies are required to maintain this breed. The aim of the present study was to assess genetic variation that is characteristic for Butana cattle in the milk protein genes CSN1S1, CSN2, CSN1S2, CSN3, LALBA, and LGB. In a first step, genomic DNA of five unrelated individuals was comparatively sequenced across all exon and flanking sequences. Ninety-three single nucleotide polymorphisms (SNPs) were identified in Butana cattle compared with the Bos taurus reference sequence at Ensembl. We confirmed the recently identified protein variants CSN2*J, CSN2*L, and LALBA*E. Fifty-two SNPs in non-coding regions are novel. Among the novel SNPs, five are located in promoter regions, three of them are in putative transcription factor binding sites (TFBSs) of the CSN1S2 promoter. Fifteen SNPs potentially affect miRNA target sites. In a second step, 50 unrelated Butana cattle were genotyped. This allowed deriving haplotypes for the casein gene cluster on BTA6. The most frequent haplotype was CSN1S1*C-CSN2*A ² -CSN1S2*A-CSN3*A (C-A ² -A-A, frequency 0.1546). Considering the newly identified CSN1S2 promoter variants, the most frequent haplotype was C-A ² -TTC-A-A (0.1046), with TTC as the promoter variant. The information on protein and promoter variants can be used for the development of conservation and breeding strategies for this local breed.

Identification of alleles and genotypes of beta-casein with DNA sequencing analysis in Chinese Holstein cow

The study reported in this Regional Research Communication aimed to analyse the genetic polymorphisms of β-casein in Chinese Holstein cows. β-casein has received considerable research interest in the dairy industry and animal breeding in recent years as a source not only of high quality protein, but also of bioactive peptides that may be linked to health effects. Morever, the polymorphic nature of β-casein and its association with milk production traits, composition, and quality also attracted several efforts in evaluating the allelic distribution of β-casein locus as a potential dairy trait marker. However, few data on beta-casein variants are available for the Chinese Holstein cow. In the present paper, one hundred and thirty three Holstein cows were included in the analysis. Results revealed the presence of 5 variants (A1, A2, A3, B and I), preponderance of the genotype A1A2 (0·353) and superiorities of A1/A2 alleles (0·432 and 0·459, respectively) in the population. Sequence analysis of β-casein gene in the cows showed four nucleotide changes in exon 7. Our study can provide reference and guidance for selection for superior milk for industrial applications and crossbreeding and genetic improvement programmes.

Monitoring protein glycation by electrospray ionization (ESI) quadrupole time-of-flight (Q-TOF) mass spectrometer

In this study electrospray ionization quadrupole time-of-flight (ESI-Q-TOF) mass spectrometry was used to investigate protein glycation. The glycated species of cytochrome C, lysozyme, and β-casein formed during glycation with d-glucose were identified and monitored in binary systems heated at 70°C under dry and aqueous conditions. Cytochrome C had multiple charges in non-glycated state, primarily changing from +13 to +17 positive charges, whereas β-casein had charge states up to +30. Upon heating with glucose at 70°C in aqueous state, attachment of one glucose molecule onto proteins was observed in each charge state. However, heating in dry state caused much more glucose attachment, leading to the formation of multiple glycoforms of proteins. By using ESI-QTOF-MS technique, formation of glycated cytochrome C containing up to 12 glucose moieties were observed, while glycated species containing 6 and 8 glucose moieties were observed for lysozyme and β-casein, respectively in various heating conditions.

Biological underpinnings of breastfeeding challenges: the role of genetics, diet, and environment on lactation physiology

Lactation is a dynamic process that has evolved to produce a complex biological fluid that provides nutritive and nonnutritive factors to the nursing offspring. It has long been assumed that once lactation is successfully initiated, the primary factor regulating milk production is infant demand. Thus, most interventions have focused on improving breastfeeding education and early lactation support. However, in addition to infant demand, increasing evidence from studies conducted in experimental animal models, production animals, and breastfeeding women suggests that a diverse array of maternal factors may also affect milk production and composition. In this review, we provide an overview of our current understanding of the role of maternal genetics and modifiable factors, such as diet and environmental exposures, on reproductive endocrinology, lactation physiology, and the ability to successfully produce milk. To identify factors that may affect lactation in women, we highlight some information gleaned from studies in experimental animal models and production animals. Finally, we highlight the gaps in current knowledge and provide commentary on future research opportunities aimed at improving lactation outcomes in breastfeeding women to improve the health of mothers and their infants.

Formation and Degradation of Beta-casomorphins in Dairy Processing

Milk proteins including casein are sources of peptides with bioactivity. One of these peptides is beta-casomorphin (BCM) which belongs to a group of opioid peptides formed from β-casein variants. Beta-casomorphin 7 (BCM7) has been demonstrated to be enzymatically released from the A1 or B β-casein variant. Epidemiological evidence suggests the peptide BCM 7 is a risk factor for development of human diseases, including increased risk of type 1 diabetes and cardiovascular diseases but this has not been thoroughly substantiated by research studies. High performance liquid chromatography coupled to UV-Vis and mass spectrometry detection as well as enzyme-linked immunosorbent assay (ELISA) has been used to analyze BCMs in dairy products. BCMs have been detected in raw cow's milk and human milk and a variety of commercial cheeses, but their presence has yet to be confirmed in commercial yoghurts. The finding that BCMs are present in cheese suggests they could also form in yoghurt, but be degraded during yoghurt processing. Whether BCMs do form in yoghurt and the amount of BCM forming or degrading at different processing steps needs further investigation and possibly will depend on the heat treatment and fermentation process used, but it remains an intriguing unknown.

Bicyclol attenuates tetracycline-induced fatty liver associated with inhibition of hepatic ER stress and apoptosis in mice

Endoplasmic reticulum (ER) stress is known to be involved in the development of several metabolic disorders, including non-alcoholic fatty liver disease (NAFLD). Tetracycline can cause hepatic steatosis, and ER stress may be involved in tetracycline-induced fatty liver. Our previous study showed that bicyclol has been proven to protect against tetracycline-induced fatty liver in mice, and ER stress may also be involved in bicyclol’s hepatoprotective effect. Therefore, this study was performed to investigate the underlying mechanisms associated with ER stress and apoptosis, by which bicyclol attenuated tetracycline-induced fatty liver in mice. Bicyclol (300 mg/kg) was given to mice by gavage 3 times. Tetracycline (200 mg/kg, intraperitoneally) was injected at 1 h after the last dose of bicyclol. At 6 h and 24 h after single dose of tetracycline injection, serum ALT, AST, TG, CHO and hepatic histopathological examinations were performed to evaluate liver injuries. Hepatic steatosis was assessed by the accumulation of hepatic TG and CHO. Moreover, hepatic apoptosis and ER stress related markers were determined by TUNEL, real-time PCR, and western blot. As a result, bicyclol significantly protected against tetracycline-induced fatty liver as evidenced by the decrease of elevated serum transaminases and hepatic triglyceride, and the attenuation of histopathological changes in mice. In addition, bicyclol remarkably alleviated hepatic apoptosis and the gene expression of caspase–3, and increased the gene expression of XIAP. The gene expressions of ER stress-related markers, including CHOP, GRP78, IRE-1α, and ATF6, which were downregulated by bicyclol pretreatment in tetracycline-injected mice. These results suggested that bicyclol protected tetracycline-induced fatty liver partly due to its ability of anti-apoptosis associated with ER stress.

Epigenetic effects of casein-derived opioid peptides in SH-SY5Y human neuroblastoma cells

Background

Casein-free, gluten-free diets have been reported to mitigate some of the inflammatory gastrointestinal and behavioral traits associated with autism, but the mechanism for this palliative effect has not been elucidated. We recently showed that the opioid peptide beta-casomorphin-7, derived from bovine (bBCM7) milk, decreases cysteine uptake, lowers levels of the antioxidant glutathione (GSH) and decreases the methyl donor S-adenosylmethionine (SAM) in both Caco-2 human GI epithelial cells and SH-SY5Y human neuroblastoma cells. While human breast milk can also release a similar peptide (hBCM-7), the bBCM7 and hBCM-7 vary greatly in potency; as the bBCM-7 is highly potent and similar to morphine in it's effects. Since SAM is required for DNA methylation, we wanted to further investigate the epigenetic effects of these food-derived opioid peptides. In the current study the main objective was to characterize functional pathways and key genes responding to DNA methylation effects of food-derived opioid peptides.

Methods

SH-SY5Y neuroblastoma cells were treated with 1 μM hBCM7 and bBCM7 and RNA and DNA were isolated after 4 h with or without treatment. Transcriptional changes were assessed using a microarray approach and CpG methylation status was analyzed at 450,000 CpG sites. Functional implications from both endpoints were evaluated via Ingenuity Pathway Analysis 4.0 and KEGG pathway analysis was performed to identify biological interactions between transcripts that were significantly altered at DNA methylation or transcriptional levels (p < 0.05, FDR <0.1).

Results

Here we show that hBCM7 and bBCM7, as well as morphine, cause epigenetic changes affecting gene pathways related to gastrointestinal disease and inflammation. These epigenetic consequences exhibited the same potency order as opiate inhibition of cysteine uptake insofar as hBCM7 was less potent than bBCM7, which was less potent than morphine.

Conclusion

Our findings indicate that epigenetic effects of milk-derived opiate peptides may contribute to GI dysfunction and inflammation in sensitive individuals. While the current study was performed using SH-SY5Y neuronal cellular models, similar actions on other cells types might combine to cause symptoms of intolerance. These actions may provide a potential contributing mechanism for the beneficial effects of a casein-free diet in alleviating gastrointestinal symptoms in neurological conditions including autism and other conditions. Lastly, our study also contributes to the evolving awareness of a “gut-brain connection”.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-015-0050-1) contains supplementary material, which is available to authorized users.

Differential neurogenic effects of casein-derived opioid peptides on neuronal stem cells: implications for redox-based epigenetic changes

Food-derived peptides, such as β-casomorphin BCM7, have potential to cross the gastrointestinal tract and blood-brain barrier and are associated with neurological disorders and neurodevelopmental disorders. We previously established a novel mechanism through which BCM7 affects the antioxidant levels in neuronal cells leading to inflammatory consequences. In the current study, we elucidated the effects of casein-derived peptides on neuronal development by using the neurogenesis of neural stem cells (NSCs) as an experimental model. First, the transient changes in intracellular thiol metabolites during NSC differentiation (neurogenesis) were investigated. Next, the neurogenic effects of food-derived opioid peptides were measured, along with changes in intracellular thiol metabolites, redox status and global DNA methylation levels. We observed that the neurogenesis of NSCs was promoted by human BCM7 to a greater extent, followed by A2-derived BCM9 in contrast to bovine BCM7, which induced increased astrocyte formation. The effect was most apparent when human BCM7 was administered for 1day starting on 3days postplating, consistent with immunocytochemistry. Furthermore, neurogenic changes regulated by bovine BCM7 and morphine were associated with an increase in the glutathione/glutathione disulfide ratio and a decrease in the S-adenosylmethionine/S-adenosylhomocysteine ratio, indicative of changes in the redox and the methylation states. Finally, bovine BCM7 and morphine decreased DNA methylation in differentiating NSCs. In conclusion, these results suggest that food-derived opioid peptides and morphine regulated neurogenesis and differentiation of NSCs through changes in the redox state and epigenetic regulation.

Milk Intolerance, Beta-Casein and Lactose

True lactose intolerance (symptoms stemming from lactose malabsorption) is less common than is widely perceived, and should be viewed as just one potential cause of cows’ milk intolerance. There is increasing evidence that A1 beta-casein, a protein produced by a major proportion of European-origin cattle but not purebred Asian or African cattle, is also associated with cows’ milk intolerance. In humans, digestion of bovine A1 beta-casein, but not the alternative A2 beta-casein, releases beta-casomorphin-7, which activates μ-opioid receptors expressed throughout the gastrointestinal tract and body. Studies in rodents show that milk containing A1 beta-casein significantly increases gastrointestinal transit time, production of dipeptidyl peptidase-4 and the inflammatory marker myeloperoxidase compared with milk containing A2 beta-casein. Co-administration of the opioid receptor antagonist naloxone blocks the myeloperoxidase and gastrointestinal motility effects, indicating opioid signaling pathway involvement. In humans, a double-blind, randomized cross-over study showed that participants consuming A1 beta-casein type cows’ milk experienced statistically significantly higher Bristol stool values compared with those receiving A2 beta-casein milk. Additionally, a statistically significant positive association between abdominal pain and stool consistency was observed when participants consumed the A1 but not the A2 diet. Further studies of the role of A1 beta-casein in milk intolerance are needed.

Gastroenterology issues in schizophrenia: why the gut matters

Genetic and environmental studies implicate immune pathologies in schizophrenia. The body's largest immune organ is the gastrointestinal (GI) tract. Historical associations of GI conditions with mental illnesses predate the introduction of antipsychotics. Current studies of antipsychotic-naïve patients support that gut dysfunction may be inherent to the schizophrenia disease process. Risk factors for schizophrenia (inflammation, food intolerances, Toxoplasma gondii exposure, cellular barrier defects) are part of biological pathways that intersect those operant in the gut. Central to GI function is a homeostatic microbial community, and early reports show that it is disrupted in schizophrenia. Bioactive and toxic products derived from digestion and microbial dysbiosis activate adaptive and innate immunity. Complement C1q, a brain-active systemic immune component, interacts with gut-related schizophrenia risk factors in clinical and experimental animal models. With accumulating evidence supporting newly discovered gut-brain physiological pathways, treatments to ameliorate brain symptoms of schizophrenia should be supplemented with therapies to correct GI dysfunction.

IgG dynamics of dietary antigens point to cerebrospinal fluid barrier or flow dysfunction in first-episode schizophrenia

Schizophrenia is a complex brain disorder that may be accompanied by idiopathic inflammation. Classic central nervous system (CNS) inflammatory disorders such as viral encephalitis or multiple sclerosis can be characterized by incongruent serum and cerebrospinal fluid (CSF) IgG due in part to localized intrathecal synthesis of antibodies. The dietary antigens, wheat gluten and bovine milk casein, can induce a humoral immune response in susceptible individuals with schizophrenia, but the correlation between the food-derived serological and intrathecal IgG response is not known. Here, we measured IgG to wheat gluten and bovine milk casein in matched serum and CSF samples from 105 individuals with first-episode schizophrenia (n=75 antipsychotic-naïve), and 61 controls. We found striking correlations in the levels of IgG response to dietary proteins between serum and CSF of schizophrenia patients, but not controls (schizophrenia, R(2)=0.34-0.55, p⩽0.0001; controls R(2)=0.05-0.06, p>0.33). A gauge of blood-CSF barrier permeability and CSF flow rate, the CSF-to-serum albumin ratio, was significantly elevated in cases compared to controls (p⩽0.001-0.003). Indicators of intrathecal IgG production, the CSF IgG index and the specific Antibody Index, were not significantly altered in schizophrenia compared to controls. Thus, the selective diffusion of bovine milk casein and wheat gluten antibodies between serum and CSF in schizophrenia may be the function of a low-level anatomical barrier dysfunction or altered CSF flow rate, which may be transient in nature.

Structural differences between bovine A(1) and A(2) β-casein alter micelle self-assembly and influence molecular chaperone activity

Within each milk protein there are many individual protein variants and marked alterations to milk functionality can occur depending on the genetic variants of each protein present. Bovine A(1) and A(2) β-casein (β-CN) are 2 variants that contribute to differences in the gelation performance of milk. The A(1) and A(2) β-CN variants differ by a single AA, the substitution of histidine for proline at position 67. β-Casein not only participates in formation of the casein micelle but also forms an oligomeric micelle itself and functions as a molecular chaperone to prevent the aggregation of a wide range of proteins, including the other caseins. Micelle assembly of A(1) and A(2) β-CN was investigated using dynamic light scattering and small-angle X-ray scattering, whereas protein functionality was assessed using fluorescence techniques and molecular chaperone assays. The A(2) β-CN variant formed smaller micelles than A(1) β-CN, with the monomer-micelle equilibrium of A(2) β-CN being shifted toward the monomer. This shift most likely arose from structural differences between the 2 β-CN variants associated with the adoption of greater polyproline-II helix in A(2) β-CN and most likely led to enhanced chaperone activity of A(2) β-CN compared with A(1) β-CN. The difference in micelle assembly, and hence chaperone activity, may provide explain differences in the functionality of homozygous A(1) and A(2) milk. The results of this study highlight that substitution of even a single AA can significantly alter the properties of an intrinsically unstructured protein such as β-CN and, in this case, may have an effect on the functionality of milk.

In vitro digestion of purified β-casein variants A(1), A(2), B, and I: effects on antioxidant and angiotensin-converting enzyme inhibitory capacity

Genetic polymorphisms of bovine milk proteins affect the protein profile of the milk and, hence, certain technological properties, such as casein (CN) number and cheese yield. However, reports show that such polymorphisms may also affect the health-related properties of milk. Therefore, to gain insight into their digestion pattern and bioactive potential, β-CN was purified from bovine milk originating from cows homozygous for the variants A(1), A(2), B, and I by a combination of cold storage, ultracentrifugation, and acid precipitation. The purity of the isolated β-CN was determined by HPLC, variants were verified by mass spectrometry, and molar extinction coefficients at λ=280nm were determined. β-Casein from each of the variants was subjected to in vitro digestion using pepsin and pancreatic enzymes. Antioxidant and angiotensin-converting enzyme (ACE) inhibitory capacities of the hydrolysates were assessed at 3 stages of digestion and related to that of the undigested samples. Neither molar extinction coefficients nor overall digestibility varied significantly between these 4 variants; however, clear differences in digestion pattern were indicated by gel electrophoresis. In particular, after 60min of pepsin followed by 5min of pancreatic enzyme digestion, one ≈4kDa peptide with the N-terminal sequence (106)H-K-E-M-P-F-P-K- was absent from β-CN variant B. This is likely a result of the (122)Ser to (122)Arg substitution in variant B introducing a novel trypsin cleavage site, leading to the changed digestion pattern. All investigated β-CN variants exhibited a significant increase in antioxidant capacity upon digestion, as measured by the Trolox-equivalent antioxidant capacity assay. After 60min of pepsin + 120min of pancreatic enzyme digestion, the accumulated increase in antioxidant capacity was ≈1.7-fold for the 4 β-CN variants. The ACE inhibitory capacity was also significantly increased by digestion, with the B variant reaching the highest inhibitory capacity at the end of digestion (60min of pepsin + 120min of pancreatic enzymes), possibly because of the observed alternative digestion pattern. These results demonstrate that genetic polymorphisms affect the digestion pattern and bioactivity of milk proteins. Moreover, their capacity for radical scavenging and ACE inhibition is affected by digestion.

Autism and nutrition: the role of the gut-brain axis

Autism spectrum disorder (ASD) is characterised by deficits in the ability to socialise, communicate and use imagination, and displays of stereotypical behaviour. It is widely accepted that ASD involves a disorder in brain development. However, the real causes of the neurodevelopmental disorders associated with ASD are not clear. In this respect, it has been found that a majority of children with ASD display gastrointestinal symptoms, and an increased intestinal permeability. Moreover, large differences in microbiotic composition between ASD patients and controls have been reported. Therefore, nutrition-related factors have been hypothesised to play a causal role in the aetiology of ASD and its symptoms. Through a review of the literature, it was found that abnormalities in carbohydrate digestion and absorption could explain some of the gastrointestinal problems observed in a subset of ASD patients, although their role in the neurological and behavioural problems remains uncertain. In addition, the relationship between an improved gut health and a reduction of symptoms in some patients was evaluated. Recent trials involving gluten-free diets, casein-free diets, and pre- and probiotic, and multivitamin supplementation show contradictive but promising results. It can be concluded that nutrition and other environmental influences might trigger an unstable base of genetic predisposition, which may lead to the development of autism, at least in a subset of ASD patients. Clear directions for further research to improve diagnosis and treatment for the different subsets of the disorder are provided.

The β-casein in camels: molecular characterization of the CSN2 gene, promoter analysis and genetic variability

The β-casein is the most abundant protein in camel milk and its encoding gene (CSN2) is considered in other species a 'major' gene for the presence of alleles associated to different level of expression. In the present paper, we report for the first time the characterization of the nucleotide sequence of the whole β-casein-encoding gene (CSN2) plus 2,141 bp at the 5'-flanking region in Camelus dromedarius. The promoter region and the complete cDNA are also provided for the first time in Camelus bactrianus. The gene is spread over 7.8 kb and consists of 9 exons varying in length from 24 bp (exon 5) to 519 bp (exon 7), and 8 introns from 95 bp (intron 5) to 1,950 bp (intron 1). The composite response element (CoRE) region was identified in the promoter, whereas the presence of mature microRNA sequences improves the knowledge on the factors putatively involved in the gene regulation. A total of 46 polymorphic sites have been detected. The transition g.2126A>G falls within the TATA-box of dromedary CSN2 promoter with a putative influence on the transcription factor binding activity. The frequency of the G allele is 0.35 in a population of 180 she-camels belonging to 4 different ecotypes. In the same population, a conservative SNP (g.4175C>A) was found at the codon 7 of the signal peptide, whereas a comparative analysis with a cDNA sequence available in the database evidenced a missense SNP (g.4180T(Leu)>G(Arg)) at exon 2. Four SNPs were found in the bactrian camel. The SNP c.666G>A is responsible for the amino acid change Met(201)→Ile and it represents the first missense allele at the β-casein in camels. Finally, five interspersed repeated elements were identified at intronic level, whereas the presence of putative bio-functional peptides belonging to ACE-inhibitor and anti-oxidative families confirms the potential protective role of the camel milk for the human nutrition.

Food-derived opioid peptides inhibit cysteine uptake with redox and epigenetic consequences

Dietary interventions like gluten-free and casein-free diets have been reported to improve intestinal, autoimmune and neurological symptoms in patients with a variety of conditions; however, the underlying mechanism of benefit for such diets remains unclear. Epigenetic programming, including CpG methylation and histone modifications, occurring during early postnatal development can influence the risk of disease in later life, and such programming may be modulated by nutritional factors such as milk and wheat, especially during the transition from a solely milk-based diet to one that includes other forms of nutrition. The hydrolytic digestion of casein (a major milk protein) and gliadin (a wheat-derived protein) releases peptides with opioid activity, and in the present study, we demonstrate that these food-derived proline-rich opioid peptides modulate cysteine uptake in cultured human neuronal and gastrointestinal (GI) epithelial cells via activation of opioid receptors. Decreases in cysteine uptake were associated with changes in the intracellular antioxidant glutathione and the methyl donor S-adenosylmethionine. Bovine and human casein-derived opioid peptides increased genome-wide DNA methylation in the transcription start site region with a potency order similar to their inhibition of cysteine uptake. Altered expression of genes involved in redox and methylation homeostasis was also observed. These results illustrate the potential of milk- and wheat-derived peptides to exert antioxidant and epigenetic changes that may be particularly important during the postnatal transition from placental to GI nutrition. Differences between peptides derived from human and bovine milk may contribute to developmental differences between breastfed and formula-fed infants. Restricted antioxidant capacity, caused by wheat- and milk-derived opioid peptides, may predispose susceptible individuals to inflammation and systemic oxidation, partly explaining the benefits of gluten-free or casein-free diets.

Seroreactive marker for inflammatory bowel disease and associations with antibodies to dietary proteins in bipolar disorder

OBJECTIVES

Immune sensitivity to wheat glutens and bovine milk caseins may affect a subset of individuals with bipolar disorder. Digested byproducts of these foods are exorphins that have the potential to impact brain physiology through action at opioid receptors. Inflammation in the gastrointestinal (GI) tract might accelerate exposure of food antigens to systemic circulation and help explain elevated gluten and casein antibody levels in individuals with bipolar disorder.

METHODS

We measured a marker of GI inflammation, anti-Saccharomyces cerevisiae antibodies (ASCA), in non-psychiatric controls (n = 207), in patients with bipolar disorder without a recent onset of psychosis (n = 226), and in patients with bipolar disorder with a recent onset of psychosis (n = 38). We compared ASCA levels to antibodies against gluten, casein, Epstein-Barr virus (EBV), herpes simplex virus 1 (HSV-1), influenza A, influenza B, measles, and Toxoplasma gondii.

RESULTS

Elevated ASCA conferred a 3.5-4.4-fold increased odds ratio of disease association (age-, race-, and gender-corrected multinomial logistic regressions, p ≤ 0.00001) that was independent of type of medication received. ASCA correlated with food antibodies in both bipolar disorder groups (R(2)  = 0.29-0.59, p ≤ 0.0005), and with measles and T. gondii immunoglobulin G (IgG) in the recent onset psychosis bipolar disorder group (R(2)  = 0.31-0.36, p ≤ 0.004-0.01).

CONCLUSIONS

Elevated seropositivity of a GI-related marker and its association with antibodies to food-derived proteins and self-reported GI symptoms suggest a GI comorbidity in at least a subgroup of individuals with bipolar disorder. Marker seroreactivity may also represent part of an overall heightened activated immune state inherent to this mood disorder.

In vitrotransport and satiety of a beta-lactoglobulin dipeptide and beta-casomorphin-7 and its metabolites

In vitrotransport of β-CM7 occurs through rapid hydrolysis into three peptide metabolites that transport at variable rates.

Physiological properties of milk ingredients released by fermentation

The demand for health-promoting food ingredients rises within an increasing market worldwide. Different milks fermented with bacteria, yeasts, moulds or enzymes from animal, plant and microbial sources offer a broad range of possibilities to cover different health aspects with new bioactive components. By the fermentation process interesting ingredients are enriched and released from the matrix, like lactoferrin, micro-nutrients, CLA and sphingolipids or synthesized, such as exo-polysaccharides and bioactive peptides. In particular, milk derived bioactive peptides exert several important health-promoting activities, such as anti-hypertensive, anti-microbial, anti-oxidative, immune-modulatory, opioid and mineral-binding properties. Milk-fermentation processes with probiotic bacteria synergistically combine health supporting bacterial and milk ingredient aspects which include new therapeutic solutions concerning hypercholesterolemia, carcinogenic intoxications, treatment of diarrhea, reduction of intestine pathogens, and supporting natural immune defense. Especially, milk-proteins and associated bioactive peptides released during microbial or enzymatic fermentation of milk offer a broad spectrum of new functional properties, for instance anti-hypertensive, anti-microbial, anti-oxidative, immuno-modulatory, opioid and mineral-binding properties. This review aimed at discussing recent research activities on physiological purposes and technical process aspects of functional components from fermented milk with a specific focus on biofunctional peptides released from fermented milk proteins.

Characterization of β-casein gene in Indian riverine buffalo

The study aimed at characterization of buffalo β-casein gene and its promoter by PCR-SSCP analysis. Complete β-casein exon VII region analysis revealed two SSCP band patterns, with pattern-I representing predominant allele B (85%) present in homozygous (genotype BB) condition and pattern-II representing a rare allele A1 present in heterozygous condition (genotype A1B). Sequencing of two patterns revealed three nucleotide substitutions at codon 68, 151 and 193 of exon VII. The cDNA sequence of buffalo β-casein gene indicated three further nucleotide substitutions between allele A1 and B at codon 10, 39, and 41. Analysis of β-casein proximal promoter region (-350 upstream to +32) revealed four SSCP band patterns. These SSCP patterns corresponded to nucleotide substitutions at seven locations within 382 bp 5' UTR region of β-casein gene. Haplotype analysis suggested pattern-I of exon VII (wild type) was associated with three types of promoters and pattern-II of exon VII (rare type) corresponded to one exclusive type of promoter. The study suggested two haplotypes of exon VII and four haplotypes of promoter for buffalo β-casein.

Rosiglitazone attenuates casein-induced hepatic endoplasmic reticulum stress in Sprague-Dawley rats: a novel model of endoplasmic reticulum stress

The proteins found in cow milk have been reported to cause systemic inflammation. Endoplasmic reticulum (ER) stress is known to be involved in the development of several metabolic disorders including insulin resistance and non-alcoholic fatty liver disease. However, the effect of thiazolidinediones (TZDs) on ER stress is still controversial. This is why we want to investigate in this study whether casein, which is the major protein in cow's milk, induces ER stress in the liver and whether rosiglitazone can attenuate these changes. Nine-week-old male Sprague-Dawley (SD) rats were separated into three groups: (1) vehicle treated; (2) daily subcutaneous injections of 1 mL 10% casein; (3) daily subcutaneous injection of 1 mL 10% casein and rosiglitazone 4 mg/[kg d]. After 6 weeks, body weight, food intake, glucose and lipid parameters, and serum AST/ALT levels were measured after an overnight fast. Real time RT-PCR and immunohistochemical staining for various ER stress markers were performed, and a TUNEL analysis was also performed. After 6 weeks, casein injection induced weight reduction, systemic inflammation, and hepatic dysfunction in SD rats. Casein injection increased both the gene and protein expression of ER stress markers in the liver and also caused hepatocyte apoptosis. Rosiglitazone treatment attenuated casein-induced systemic inflammation, ER stress, deteriorated liver function, and increased apoptosis. In conclusion, our results may provide further insight into the effects of casein on chronic inflammatory diseases, and to have a better understanding of the mechanism of the anti-inflammatory properties of rosiglitazone regardless of its hypoglycemic effect.

Towards the improved discovery and design of functional peptides: common features of diverse classes permit generalized prediction of bioactivity

The conventional wisdom is that certain classes of bioactive peptides have specific structural features that endow their particular functions. Accordingly, predictions of bioactivity have focused on particular subgroups, such as antimicrobial peptides. We hypothesized that bioactive peptides may share more general features, and assessed this by contrasting the predictive power of existing antimicrobial predictors as well as a novel general predictor, PeptideRanker, across different classes of peptides.We observed that existing antimicrobial predictors had reasonable predictive power to identify peptides of certain other classes i.e. toxin and venom peptides. We trained two general predictors of peptide bioactivity, one focused on short peptides (4-20 amino acids) and one focused on long peptides (> 20 amino acids). These general predictors had performance that was typically as good as, or better than, that of specific predictors. We noted some striking differences in the features of short peptide and long peptide predictions, in particular, high scoring short peptides favour phenylalanine. This is consistent with the hypothesis that short and long peptides have different functional constraints, perhaps reflecting the difficulty for typical short peptides in supporting independent tertiary structure.We conclude that there are general shared features of bioactive peptides across different functional classes, indicating that computational prediction may accelerate the discovery of novel bioactive peptides and aid in the improved design of existing peptides, across many functional classes. An implementation of the predictive method, PeptideRanker, may be used to identify among a set of peptides those that may be more likely to be bioactive.

Adsorption of unstructured protein β-casein to hydrophobic and charged surfaces

In this Monte Carlo simulation study we use mesoscopic modeling to show that β-casein, an unstructured milk protein, adsorbs to surfaces not only due to direct electrostatic and hydrophobic interactions but also due to structural rearrangement and charge regulation due to proton uptake and release. β-casein acts as an amphiphilic chameleon, changing properties according to the chemical environment, and binding is observed to both positively and negatively charged surfaces. The binding mechanisms, however, are fundamentally different. A detailed, per-residue-level analysis shows that the adsorption process is controlled by a few very specific regions of the protein and that these change dramatically with pH. Caseins, being the most abundant proteins in milk, are crucial for the properties of fermented dairy products, such as nutrition, texture, and viscosity, but may also influence adhesion to packaging materials. The latter leads to product losses of about 10%, leading to economical and environmental problems.

β-Casomorphin-7 attenuates the development of nephropathy in type I diabetes via inhibition of epithelial-mesenchymal transition of renal tubular epithelial cells

This study was designed to investigate the putative protective effect of β-casomorphin-7 on diabetic nephropathy in a rat model, and to explore the possible mechanism of this effect. SD rats were randomly divided into the following three groups: control group, diabetes group and β-casomorphin-7-treatment group. All rats were euthanized after 30 days with or without β-casomorphin-7 treatment. Biochemical parameters including blood glucose and renal function were quantified. The concentration of plasma TGF-β1 was measured by ELISA. Histopathological changes to the kidney were studied by Masson and Sirius red staining. Expressions of α-smooth muscle actin (α-SMA), E-cadherin, vimentin, cytokeratin19 and TGF-β1 mRNA in rat renal cortices were analyzed by real-time PCR. Changes in α-SMA and E-cadherin protein expression in rat renal cortices were quantified by Western blot. β-Casomorphin-7 treatment of diabetic rats reduced urinary glucose, urinary protein, serum creatinine, blood urinary nitrogen, plasma TGF-β1 and the ratio of kidney: body weight. Masson and Sirius red staining showed that β-casomorphin-7 treatment attenuated renal interstitial fibrosis in diabetic rats. Compared to the control rats, diabetic rats had elevated expressions of α-SMA, vimentin and TGF-β1 mRNA and α -SMA protein and decreased expression of E-cadherin and cytokeratin19 mRNA, and E-cadherin protein. β-Casomorphin-7 treatment of diabetic rats partially normalized these changes. Our results suggest that administration of β-casomorphin-7 attenuates renal interstitial fibrosis caused by diabetes. This protective effect may be associated, in part, with down regulation of epithelial-mesenchymal transition of renal tubular epithelial cells.

The exogenous opioid peptides and DPPIV serum activity in infants with apnoea expressed as apparent life threatening events (ALTE)

Casein-derived peptides have been suggested to play a role in sudden infant death syndrome (SIDS). In this study, we have determined the content of bovine β-casomorphin-7 (bBCM-7) and the activity of dipeptidyl peptidase-IV (DPPIV) in sera of infants with apparent life threatening events (ALTE syndromes, 'near miss SIDS'). We have found that the sera of some infants after an apnoea event contained more β-casomorphin-7 than that of the healthy infants in the same age. In all the children after an apnoea event, however, a lowered DPPIV was detected. We suspect that the low activity of that peptidase may be responsible for opioid-induced respiratory depression, induced by bBCM-7 in the general circulation.

Immune activation by casein dietary antigens in bipolar disorder

OBJECTIVES

  Inflammation and other immune processes are increasingly linked to psychiatric diseases. Antigenic triggers specific to bipolar disorder are not yet defined. We tested whether antibodies to bovine milk caseins were associated with bipolar disorder, and whether patients recognized different epitopes of the casein protein than control individuals.

METHODS

  Anti-bovine casein immunoglobulin G (IgG) levels were measured with solid-phase immunoassays in 75 individuals with bipolar disorder and 65 controls. Epitope recognition was evaluated in immunoassays by cross neutralization with anti-bovine casein polyclonal antibodies of defined reactivity. Group-specific reactivity and associations with symptom severity scores were detected with age-, gender-, and race-controlled regression models.

RESULTS

  Individuals with bipolar disorder had significantly elevated anti-casein IgG (t-test, p ≤0.001) compared to controls. Casein IgG seropositivity conferred odds ratios of 3.97 for bipolar disorder [n=75, 95% confidence interval (CI): 1.31-12.08, p ≤0.015], 5.26 for the bipolar I subtype (n=56, 95% CI: 1.66-16.64, p ≤0.005), and 3.98 for bipolar disorder with psychosis (n=54, 95% CI: 1.32-12.00, p ≤0.014). Lithium and/or antipsychotic medication did not significantly affect anti-casein IgG levels. Casein IgG measures correlated with severity of manic (R(2) =0.15, 95% CI: 0.05-0.24, p ≤0.02) but not depressive symptoms. Unlike controls, sera from individuals with bipolar disorder did not inhibit binding of casein-reactive animal sera (t-test/χ(2) , p ≤0.0001).

CONCLUSIONS

  Anti-casein IgG associations with bipolar I diagnoses, psychotic symptom history, and mania severity scores suggest that casein-related immune activation may relate to the psychosis and mania components of this mood disorder. Case-control differences in epitope recognition implicate disease-related alterations in how the casein molecule is digested and/or how resulting casein-derived structures are rendered immunogenic.

The rising incidence of type 1 diabetes mellitus and the role of environmental factors--three decade experience in a primary care health center in Saudi Arabia

BACKGROUND

The incidence of type 1 diabetes has been increasing all over the world including Saudi Arabia and environmental factors have been suggested to play an important role in its etiology.

OBJECTIVE

The aim of this study was to evaluate if there are any contributory roles of various environmental factors in the rising incidence of type 1 diabetes in children in the Eastern Province of Saudi Arabia.

METHODS

We conducted a retrospective study of Saudi Arab subjects (n = 119) diagnosed between 1980 and 2009 with type 1 diabetes and these subjects were classified to six groups on the basis of the onset of diabetes.

RESULTS

119 subjects (61 boys and 58 girls) with confirmed diagnosis of type 1 diabetes met the study eligibility criteria. 89 children (74%) presented with ketoacidosis. The mean age of onset was 4 3/4 years for Group II and age of onset increased to above 8 years on subsequent years. Excessive weight gain was noted in all study groups. No etiological influences of maternal age at birth, birth order, birth weight, early introduction of cow's milk and cereals, infections and vaccines as well as nitrate levels in drinking water were noted in any of the groups. The predicted doubling of diabetes in young children below 5 years as in previous studies was not found in our study.

CONCLUSIONS

The rising incidence of type 1 diabetes over the last 30 years is not proved to have been influenced by various environmental factors.

Subunit and whole molecule specificity of the anti-bovine casein immune response in recent onset psychosis and schizophrenia

Previous studies show increased antibody levels to bovine casein in some individuals with schizophrenia. The immunogenicity of specific domains of bovine casein varies among people with milk sensitivities and thus could vary among different neuropsychiatric disorders. Using ELISAs and immunoblotting, we characterized IgG class antibody specificity to whole bovine casein and to the alpha(s), beta, and kappa subunits in individuals with recent onset psychosis (n=95), long-term schizophrenia (n=103), and non-psychiatric controls (n=65). In both patient groups, we found elevated IgG to casein proteins, particularly to whole casein and the alpha(s) subunit (p<or=0.0001). Odds ratios of casein seroprevalence for recent onset psychosis (age-, gender-, race-, smoking-adjusted) were significant for whole casein (8.13, p<or=0.0001), and the alpha(s) (7.89, p<or=0.0001), beta (5.23, p<or=0.001) and kappa (5.70, p<or=0.0001) subunits. Odds ratios for long-term schizophrenia were significant for whole casein (7.85, p<or=0.0001), and the alpha(s) (4.78, p<or=0.003) and kappa (4.92, p<or=0.004) subunits. Within the recent onset group, odds ratios were particularly significant for a subgroup of people with psychotic disorders that included major depressive disorders (8.22-16.48, p<or=0.0001). In a different recent onset subgroup (schizophrenia-spectrum disorders), PANSS scores for negative symptoms were correlated with casein antibody levels for the alpha(s) and kappa subunits (p<or=0.001-0.01). Immunoblotting patterns also exhibited group specificity, with kappa predominant in recent onset and alpha(s) in schizophrenia (Fisher's Exact Test, p<or=0.001). The elevated IgG and unique patterns of antibody specificity to bovine casein among diagnostic groups provide a rationale for clinical trials to evaluate efficacies of dietary modifications in individuals with neuropsychiatric diseases.

Beta-casomorphins-7 in infants on different type of feeding and different levels of psychomotor development

Casomorphins are the most important during the first year of life, when postnatal formation is most active and milk is the main source of both nutritive and biologically active material for infants. This study was conducted on a total of 90 infants, of which 37 were fed with breast milk and 53 were fed with formula containing cow milk. The study has firstly indicated substances with immunoreactivity of human (irHCM) and bovine (irBCM) beta-casomorphins-7 in blood plasma of naturally and artificially fed infants, respectively. irHCM and irBCM were detected both in the morning before feeding (basal level), and 3h after feeding. Elevation of irHCM and irBCM levels after feeding was detected mainly in infants in the first 3 months of life. Chromatographic characterization of the material with irBCM has demonstrated that it has the same molecular mass and polarity as synthetic bovine beta-casomorphin-7. The highest basal irHCM was observed in breast-fed infants with normal psychomotor development and muscle tone. In contrast, elevated basal irBCM was found in formula-fed infants showing delay in psychomotor development and heightened muscle tone. Among formula-fed infants with normal development, the rate of this parameter directly correlated to basal irBCM. The data indicate that breast feeding has an advantage over artificial feeding for infants' development during the first year of life and support the hypothesis for deterioration of bovine casomorphin elimination as a risk factor for delay in psychomotor development and other diseases such as autism.

An integrated top-down and bottom-up strategy for broadly characterizing protein isoforms and modifications

We present an integrated top-down and bottom-up approach that is facilitated by concurrent liquid chromatography-mass spectrometry (LC-MS) analysis and fraction collection for comprehensive high-throughput intact protein profiling. The approach employs high-resolution, reversed-phase (RP) LC separations coupled on-line with a 12 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer to profile and tentatively identify modified proteins, using detected intact protein masses in conjunction with bare protein identifications from the bottom-up analysis of the corresponding LC fractions. Selected identifications are incorporated into a target ion list for subsequent off-line gas-phase fragmentation that uses an aliquot of the original fraction used for bottom-up analysis. In a proof-of-principle demonstration, this comprehensive strategy was applied to identify protein isoforms arising from various amino acid modifications (e.g., acetylation, phosphorylation) and genetic variants (e.g., single nucleotide polymorphisms, SNPs). This strategy overcomes major limitations of traditional bottom-up (e.g., inability to characterize multiple unexpected protein isoforms and genetic variants) and top-down (e.g., low throughput) approaches.

Changing trends in mastitis

The global dairy industry, the predominant pathogens causing mastitis, our understanding of mastitis pathogens and the host response to intramammary infection are changing rapidly. This paper aims to discuss changes in each of these aspects. Globalisation, energy demands, human population growth and climate change all affect the dairy industry. In many western countries, control programs for contagious mastitis have been in place for decades, resulting in a decrease in occurrence of Streptococcus agalactiae and Staphylococcus aureus mastitis and an increase in the relative impact of Streptococcus uberis and Escherichia coli mastitis. In some countries, Klebsiella spp. or Streptococcus dysgalactiae are appearing as important causes of mastitis. Differences between countries in legislation, veterinary and laboratory services and farmers' management practices affect the distribution and impact of mastitis pathogens. For pathogens that have traditionally been categorised as contagious, strain adaptation to human and bovine hosts has been recognised. For pathogens that are often categorised as environmental, strains causing transient and chronic infections are distinguished. The genetic basis underlying host adaptation and mechanisms of infection is being unravelled. Genomic information on pathogens and their hosts and improved knowledge of the host's innate and acquired immune responses to intramammary infections provide opportunities to expand our understanding of bovine mastitis. These developments will undoubtedly contribute to novel approaches to mastitis diagnostics and control.

Casein haplotypes and their association with milk production traits in Norwegian Red cattle

A high resolution SNP map was constructed for the bovine casein region to identify haplotype structures and study associations with milk traits in Norwegian Red cattle. Our analyses suggest separation of the casein cluster into two haplotype blocks, one consisting of the CSN1S1, CSN2 and CSN1S2 genes and another one consisting of the CSN3 gene. Highly significant associations with both protein and milk yield were found for both single SNPs and haplotypes within the CSN1S1-CSN2-CSN1S2 haplotype block. In contrast, no significant association was found for single SNPs or haplotypes within the CSN3 block. Our results point towards CSN2 and CSN1S2 as the most likely loci harbouring the underlying causative DNA variation. In our study, the most significant results were found for the SNP CSN2_67 with the C allele consistently associated with both higher protein and milk yields. CSN2_67 calls a C to an A substitution at codon 67 in β-casein gene resulting in histidine replacing proline in the amino acid sequence. This polymorphism determines the protein variants A1/B (CSN2_67 A allele) versus A2/A3 (CSN2_67 C allele). Other studies have suggested that a high consumption of A1/B milk may affect human health by increasing the risk of diabetes and heart diseases. Altogether these results argue for an increase in the frequency of the CSN2_67 C allele or haplotypes containing this allele in the Norwegian Red cattle population by selective breeding.