Effect of high in comparison to low dairy intake intervention on markers of bone and cartilage remodeling and phosphate metabolism in healthy adults with overweight

BACKGROUND

In the ageing population, issues with bone and joint health are highly prevalent. Both beneficial and potential risks of dairy products on bone and joint health are reported in epidemiological studies. Furthermore, the phosphorus (P) load from dairy could potentially lead to unfavorable changes in P metabolism.

OBJECTIVE

To investigate the effect of dairy intake on markers of bone and joint metabolism and P metabolism in an intervention study with high and low dairy intake.

METHODS

In a post hoc analysis of a randomized cross-over trial with overweight adults, the effect of a standardized high dairy intake [HDI (5-6 dairy portions per day) versus low dairy intake (LDI, ≤ 1 dairy portion/day)] for 6 weeks on markers of bone and joint health was assessed using enzyme-linked immunosorbent assays and electrochemiluminescence immunoassays. Markers indicative for cartilage breakdown, including urinary CTX-II, serum COMP and 4-hydroxyproline, and markers indicative for bone remodeling, such as serum CTX-I, PTH, 25(OH)D, osteocalcin, P1NP and FGF23, were investigated using linear mixed models. Furthermore, changes in P metabolism, including the main phosphate-regulating hormone FGF23 were explored.

RESULTS

This study was completed by 46 adults (57% female, age 59 ± 4 years, BMI 28 ± 2 kg/m2). Following HDI, markers such as urinary CTX-II excretion, COMP, 25(OH)D, PTH and CTX-I were significantly lower after HDI, as compared to LDI. For example, CTX-II excretion was 1688 ng/24 h at HDI, while it was 2050 ng/24 h at LDI (p < 0.001). Concurrently, P intake was higher at HDI than at LDI (2090 vs 1313 mg/day, p < 0.001). While plasma P levels did not differ (1.03 vs 1.04 mmol/L in LDI, p = 0.36), urinary P excretion was higher at HDI than at LDI (31 vs 28 mmol/L, p = 0.04). FGF23 levels tended to be higher at HDI than at LDI (76.3 vs. 72.9 RU/mL, p = 0.07).

CONCLUSIONS

HDI, as compared to LDI, reduced markers that are indicative for joint and bone resorption and bone turnover. No changes in P metabolism were observed.

CLINICAL TRIAL REGISTRY

This trial was registered at https://trialsearch.who.int/Trial2.aspx?TrialID=NTR4899 as NTR4899.

Milk fat globule membrane modulates inflammatory pathways in human monocytes: A crossover human intervention study

BACKGROUND

Intake of high-fat foods raises postprandial plasma triglycerides and inflammatory markers, which may depend on the type of fat ingested. Dairy products are commonly consumed, but not much is known about the impact of milk fat and the milk fat globule membrane on postprandial inflammation. Here, we aimed to study the effect of milk fat with and without milk fat globule membrane and a vegetable fat blend on post-prandial inflammation, with a focus on blood monocyte gene expression.

METHODS

We performed a randomized, double-blind cross-over trial in 37 middle-aged healthy male and female volunteers (BMI 22-27 kg/m2). The participants consumed a meal shake containing 95.5 g of fat consisting of either a vegetable fat blend (VEGE), anhydrous milk fat (AMF, without milk fat globule membrane), or cream (CREAM, containing milk fat globule membrane). Blood monocytes were collected at 0 h and 6 h postprandially and used for bulk RNA sequencing and ex vivo stimulation with LPS.

RESULTS

Consumption of all three shakes significantly decreased the percentage of classical monocytes and increased the percentages of intermediate monocytes and non-classical monocytes. No differences in these measures were observed between shakes. Using a threshold of p < 0.01, 787 genes were differentially regulated postprandially between the three shakes. 89 genes were differentially regulated postprandially between AMF and VEGE, 373 genes between AMF and CREAM, and 667 genes between VEGE and CREAM, indicating that the effect of CREAM on monocyte gene expression was distinct from AMF and VEGE. Pathway analyses showed that VEGE significantly increased the expression of genes involved in inflammatory pathways, whereas this was less pronounced after AMF and not observed after CREAM. In addition, CREAM significantly down-regulated the expression of genes involved in energy metabolism-related pathways, such as glycolysis, TCA cycle, and oxidative phosphorylation, as well as HIF-1 signaling.

CONCLUSION

Compared to the consumption of an anhydrous milk fat without milk fat globule membrane and a vegetable fat blend, the consumption of cream with milk fat globule membrane downregulated inflammatory pathways in blood monocytes, thus suggesting a potential inflammation inhibitory effect of milk fat globule membrane.

Flood Control: How Milk-Derived Extracellular Vesicles Can Help to Improve the Intestinal Barrier Function and Break the Gut-Joint Axis in Rheumatoid Arthritis

Many studies provided compelling evidence that extracellular vesicles (EVs) are involved in the regulation of the immune response, acting as both enhancers and dampeners of the immune system, depending on the source and type of vesicle. Research, including ours, has shown anti-inflammatory effects of milk-derived EVs, using human breast milk as well as bovine colostrum and store-bought pasteurized cow milk, in in vitro systems as well as therapeutically in animal models. Although it is not completely elucidated which proteins and miRNAs within the milk-derived EVs contribute to these immunosuppressive capacities, one proposed mechanism of action of the EVs is via the modulation of the crosstalk between the (intestinal) microbiome and their host health. There is increasing awareness that the gut plays an important role in many inflammatory diseases. Enhanced intestinal leakiness, dysbiosis of the gut microbiome, and bowel inflammation are not only associated with intestinal diseases like colitis and Crohn's disease, but also characteristic for systemic inflammatory diseases such as lupus, multiple sclerosis, and rheumatoid arthritis (RA). Strategies to target the gut, and especially its microbiome, are under investigation and hold a promise as a therapeutic intervention for these diseases. The use of milk-derived EVs, either as stand-alone drug or as a drug carrier, is often suggested in recent years. Several research groups have studied the tolerance and safety of using milk-derived EVs in animal models. Due to its composition, milk-derived EVs are highly biocompatible and have limited immunogenicity even cross species. Furthermore, it has been demonstrated that milk-derived EVs, when taken up in the gastro-intestinal tract, stay intact after absorption, indicating excellent stability. These characteristics make milk-derived EVs very suitable as drug carriers, but also by themselves, these EVs already have a substantial immunoregulatory function, and even without loading, these vesicles can act as therapeutics. In this review, we will address the immunomodulating capacity of milk-derived EVs and discuss their potential as therapy for RA patients.

Review criteria

The search terms "extracellular vesicles", "exosomes", "microvesicles", "rheumatoid arthritis", "gut-joint axis", "milk", and "experimental arthritis" were used. English-language full text papers (published between 1980 and 2021) were identified from PubMed and Google Scholar databases. The reference list for each paper was further searched to identify additional relevant articles.

Regular Industrial Processing of Bovine Milk Impacts the Integrity and Molecular Composition of Extracellular Vesicles

BACKGROUND

Bovine milk contains extracellular vesicles (EVs), which act as mediators of intercellular communication by regulating the recipients' cellular processes via their selectively incorporated bioactive molecules. Because some of these EV components are evolutionarily conserved, EVs present in commercial milk might have the potential to regulate cellular processes in human consumers.

OBJECTIVES

Because commercial milk is subjected to industrial processing, we investigated its effect on the number and integrity of isolated milk EVs and their bioactive components. For this, we compared EVs isolated from raw bovine milk with EVs isolated from different types of commercial milk, including pasteurized milk, either homogenized or not, and ultra heat treated (UHT) milk.

METHODS

EVs were separated from other milk components by differential centrifugation, followed by density gradient ultracentrifugation. EVs from different milk types were compared by single-particle high-resolution fluorescence-based flow cytometry to determine EV numbers, Cryo-electron microscopy to visualize EV integrity and morphology, western blot analysis to investigate EV-associated protein cargo, and RNA analysis to assess total small RNA concentration and milk-EV-specific microRNA expression.

RESULTS

In UHT milk, we could not detect intact EVs. Interestingly, although pasteurization (irrespective of homogenization) did not affect mean ± SD EV numbers (3.4 × 108 ± 1.2 × 108-2.8 × 108 ± 0.3 × 107 compared with 3.1 × 108 ± 1.2 × 108 in raw milk), it affected EV integrity and appearance, altered their protein signature, and resulted in a loss of milk-EV-associated RNAs (from 40.2 ± 3.4 ng/μL in raw milk to 17.7 ± 5.4-23.3 ± 10.0 mg/μL in processed milk, P < 0.05).

CONCLUSIONS

Commercial milk, that has been heated by either pasteurization or UHT, contains fewer or no intact EVs, respectively. Although most EVs seemed resistant to pasteurization based on particle numbers, their integrity was affected and their molecular composition was altered. Thus, the possible transfer of bioactive components via bovine milk EVs to human consumers is likely diminished or altered in heat-treated commercial milk.

Free fatty acid release from vegetable and bovine milk fat-based infant formulas and human milk during two-phase in vitro digestion

The profile of fatty acids released during in vitro digestion of vegetable and bovine milk fat-based infant formula differ.

Correction: Free fatty acid release from vegetable and bovine milk fat-based infant formulas and human milk during two-phase in vitro digestion

Correction for ‘Free fatty acid release from vegetable and bovine milk fat-based infant formulas and human milk during two-phase in vitro digestion’ by Jeske H. J. Hageman et al., Food Funct., 2019, 10, 2102–2113.

Bovine Lactoferrin Enhances TLR7-Mediated Responses in Plasmacytoid Dendritic Cells in Elderly Women: Results From a Nutritional Intervention Study With Bovine Lactoferrin, GOS and Vitamin D

During aging the immune system is dysregulated. Especially plasmacytoid dendritic cells (pDCs) and myeloid DCs (mDCs) have reduced Toll like receptor (TLR)-mediated responses resulting in increased susceptibility to infections. Consumption of bovine lactoferrin (bLF) has been shown to reduce infections with viruses. Galacto-oligosacharides (GOS) and vitamin D are associated with reduced pro-inflammatory cytokine levels in serum, and increased TLR7/8 responses, respectively. A double-blind placebo-controlled nutritional intervention study in elderly women was performed, to investigate the potential of bLF, GOS, and vitamin D to restore TLR responsiveness of pDCs and mDCs and to reduce inflammatory markers in serum. The nutritional intervention group (n = 15) received bLF for 3 weeks, followed by 3 weeks of bLF + GOS, and subsequently 3 weeks of bLF + GOS + vitamin D. The placebo group (n = 15) received maltodextrin for 9 weeks. Every 3 weeks, blood was collected and TLR responses of pDCs and mDCs, and inflammation-related markers in serum were measured. After 3 weeks of bLF supplementation, increased TLR7/8 and TLR1/2 responses were observed in pDCs of the nutritional intervention group compared to the placebo group. When the effects of the entire nutritional intervention were investigated, increased TLR1/2 mediated responses in mDCs were observed, and in serum sVCAM tended to decrease. Finally, based on the RAND-36 questionnaire physical function tended to improve in the intervention group. Since especially TLR7-mediated responses in pDCs were enhanced after bLF supplementation compared to placebo, this suggests that bLF may contribute to antiviral responses mediated by pDC in elderly women.Clinical trial registry number: NCT03026244, clinicaltrials.gov:

Crossreactivity to vinculin and microbes provides a molecular basis for HLA-based protection against rheumatoid arthritis

The HLA locus is the strongest risk factor for anti-citrullinated protein antibody (ACPA)(+) rheumatoid arthritis (RA). Despite considerable efforts in the last 35 years, this association is poorly understood. Here we identify (citrullinated) vinculin, present in the joints of ACPA(+) RA patients, as an autoantigen targeted by ACPA and CD4(+) T cells. These T cells recognize an epitope with the core sequence DERAA, which is also found in many microbes and in protective HLA-DRB1*13 molecules, presented by predisposing HLA-DQ molecules. Moreover, these T cells crossreact with vinculin-derived and microbial-derived DERAA epitopes. Intriguingly, DERAA-directed T cells are not detected in HLA-DRB1*13(+) donors, indicating that the DERAA epitope from HLA-DRB1*13 mediates (thymic) tolerance in these donors and explaining the protective effects associated with HLA-DRB1*13. Together our data indicate the involvement of pathogen-induced DERAA-directed T cells in the HLA-RA association and provide a molecular basis for the contribution of protective/predisposing HLA alleles.

Functional role and mechanisms of sialyllactose and other sialylated milk oligosaccharides

Human milk is a rich source of oligosaccharides. Acidic oligosaccharides, such as sialyllactose (SL), contain sialic acid (SA) residues. In human milk, approximately 73% of SA is bound to oligosaccharides, whereas only 3% is present in free form. Oligosaccharides are highly resistant to hydrolysis in the gastrointestinal tract. Only a small portion of the available oligosaccharides in breast milk is absorbed in the neonatal small intestine. SL and sialylated oligosaccharides are thought to have significant health benefits for the neonate, because of their roles in supporting resistance to pathogens, gut maturation, immune function, and cognitive development. The need for SA to allow proper development during the neonatal period is thought to exceed the endogenous synthesis. Therefore, these structures are important nutrients for the neonate. Based on the potential benefits, SL and sialylated oligosaccharides may be interesting components for application in infant nutrition. Once the hurdle of limited availability of these oligosaccharides has been overcome, their functionality can be explored in more detail, and supplementation of infant formula may become feasible.

Protection against anti-citrullinated protein antibody-positive rheumatoid arthritis is predominantly associated with HLA-DRB1*1301: a meta-analysis of HLA-DRB1 associations with anti-citrullinated protein antibody-positive and anti-citrullinated protein antibody-negative rheumatoid arthritis in four European populations

OBJECTIVE

The protective effect of HLA-DRB1 alleles on the development of rheumatoid arthritis (RA) is poorly understood. The aim of this study was to perform a meta-analysis of 4 European populations to investigate which HLA-DRB1 alleles are associated with protection in anti-citrullinated protein antibody (ACPA)-positive RA and ACPA-negative RA.

METHODS

Data for >2,800 patients and >3,000 control subjects for whom information on HLA-DRB1 typing and ACPA status was available were collected from 4 European countries: Norway, Sweden, The Netherlands, and Spain. The odds ratios (ORs) and 95% confidence intervals (95% CIs) associated with the different HLA-DRB1 alleles were analyzed in a combined meta-analysis focused on protective alleles and classifications. The analysis of ACPA-positive RA was stratified for the shared epitope (SE) alleles, to correct for skewing due to this association.

RESULTS

In ACPA-positive RA, the only alleles that conveyed protection after stratification for SE were HLA-DRB1*13 alleles (OR 0.54 [95% CI 0.38-0.77]). The protective effect of the allele classifications based on the DERAA and D70 sequences was no longer present after exclusion of DRB1*13 (for D70, OR 0.97 [95% CI 0.75-1.25]), indicating that DRB1*13, rather than the DERAA or D70 sequence as such, is associated with protection. Among the DRB1*13 alleles, only DRB1*1301 was associated with protection (OR 0.24 [95% CI 0.09-0.59]). Protection appeared to follow a north-to-south gradient, with the strongest association in northern European countries. In ACPA-negative RA, there were no robust associations with HLA-DRB1 alleles.

CONCLUSION

Our data do not support any of the classifications of protective alleles and indicate that protection against ACPA-positive RA is predominantly associated with HLA-DRB1*1301.

Identification of citrullinated vimentin peptides as T cell epitopes in HLA-DR4-positive patients with rheumatoid arthritis

OBJECTIVE

Antibodies directed against citrullinated proteins (ACPAs) are highly specific for rheumatoid arthritis (RA). The production of ACPAs is most likely dependent on the presence of T cells, since ACPAs undergo isotype switching and are associated with the shared epitope (SE)-containing HLA-DRB1 alleles. Vimentin is a likely candidate protein for T cell recognition, since >90% of patients positive for ACPAs that are reactive with (peptides derived from) citrullinated vimentin carry SE-containing HLA-DRB1 alleles. The aim of this study was to identify citrullinated vimentin peptides that are presented to HLA-DRB1*0401-restricted T cells.

METHODS

HLA-DR4-transgenic mice were immunized with all possible citrulline-containing peptides derived from vimentin, and T cell reactivity was analyzed. Peptides recognized in a citrulline-specific manner by T cells were selected and analyzed for their ability to be processed from the entire vimentin protein. A first inventory of the selected epitopes recognized by T cells was performed using peripheral blood mononuclear cells (PBMCs) from ACPA+, HLA-DR4+ patients with RA.

RESULTS

A citrulline-specific response was observed for 2 of the peptides analyzed in DR4-transgenic mice. These peptides were found to be naturally processed from the vimentin protein, since citrullinated vimentin was recognized by peptide-specific T cells. T cell reactivity against these peptides was also observed in cultures of PBMCs from RA patients.

CONCLUSION

This study identifies, for the first time, 2 naturally processed peptides from vimentin that are recognized by HLA-DRB1*0401-restricted T cells in a citrulline-specific manner. These peptides can be recognized by T cells in ACPA+, HLA-DR4+ patients with RA, as shown in a first inventory.

Association of a single-nucleotide polymorphism in CD40 with the rate of joint destruction in rheumatoid arthritis

OBJECTIVE

The severity of joint destruction in rheumatoid arthritis (RA) is highly variable from patient to patient and is influenced by genetic factors. Genome-wide association studies have enormously boosted the field of the genetics of RA susceptibility, but risk loci for RA severity remain poorly defined. A recent meta-analysis of genome-wide association studies identified 6 genetic regions for susceptibility to autoantibody-positive RA: CD40, KIF5A/PIP4K2C, CDK6, CCL21, PRKCQ, and MMEL1/TNFRSF14. The purpose of this study was to investigate whether these newly described genetic regions are associated with the rate of joint destruction.

METHODS

RA patients enrolled in the Leiden Early Arthritis Clinic were studied (n=563). Yearly radiographs were scored using the Sharp/van der Heijde method (median followup 5 years; maximum followup 9 years). The rate of joint destruction between genotype groups was compared using a linear mixed model, correcting for age, sex, and treatment strategies. A total of 393 anti-citrullinated protein antibody (ACPA)-positive RA patients from the North American Rheumatoid Arthritis Consortium (NARAC) who had radiographic data available were used for the replication study.

RESULTS

The TT and CC/CG genotypes of 2 single-nucleotide polymorphisms, rs4810485 (CD40) and rs42041 (CDK6), respectively, were associated with a higher rate of joint destruction in ACPA-positive RA patients (P=0.003 and P=0.012, respectively), with rs4810485 being significant after Bonferroni correction for multiple testing. The association of the CD40 minor allele with the rate of radiographic progression was replicated in the NARAC cohort (P=0.021).

CONCLUSION

A polymorphism in the CD40 locus is associated with the rate of joint destruction in patients with ACPA-positive RA. Our findings provide one of the first non-HLA-related genetic severity factors that has been replicated.

Protection against rheumatoid arthritis by HLA: nature and nurture

Rheumatoid arthritis (RA) is a complex genetic disorder in which the HLA region contributes most to the genetic risk. HLA-DRB1 molecules containing the amino acid sequence QKRAA/QRRAA/RRRAA (ie, HLA-DRB1*0101, *0102, *0401, *0404, *0405, *0408, *0410, *1001 and *1402) at position 70-74 in the third hypervariable region of the DRB1 chain are associated with susceptibility to RA. HLA-DRB1 molecules containing the amino acids "DERAA" (ie, HLA-DRB1*0103, *0402, *1102, *1103, *1301, *1302 and *1304) at the same position are associated with protection from RA. Interestingly, not only inherited but also non-inherited HLA-antigens from the mother can influence RA susceptibility. A protective effect of "DERAA"-containing HLA-DRB1 alleles as non-inherited maternal antigen (NIMA) has recently been described. The underlying mechanism of this protective effect is currently unknown, although a possible explanation is covered below. In this review, an overview of the current knowledge on protection against RA is given and the inherited and NIMA effect of "DERAA"-containing HLA-DRB1 alleles are compared.

Risk of progression from undifferentiated arthritis to rheumatoid arthritis: the effect of the PTPN22 1858T-allele in anti-citrullinated peptide antibody positive patients

OBJECTIVES

Anti-citrullinated peptide antibodies (ACPA) and the C1858T missense single-nucleotide polymorphism (SNP) in the PTPN22 gene are both associated with the development of rheumatoid arthritis (RA). We investigated whether the combination of these two biomarkers yielded better test characteristics to predict progression from undifferentiated arthritis (UA) to RA compared with ACPA alone.

METHODS

A total of 394 individuals with UA from a Dutch population-based inception cohort were included in this study. At baseline, ACPA were measured and the PTPN22 C1858T and HLA-DRB1 genotypes determined. Progression to RA was monitored at 1 yr after entry into the cohort.

RESULTS

A priori, UA patients had a 35% (95% CI 30-40%) risk of developing RA, which increased to 66% (95% CI 57-75%) in patients who were ACPA-positive. There was an additional, although non-significant (P = 0.34), increase in RA risk to 76% (95% CI 57-90%) when patients were positive for both ACPA and the PTPN22 1858T-allele. The area under the receiver operator characteristic curve increased from 0.68 for ACPA-status alone to 0.70 for the combination of ACPA-status and the PTPN22 C1858T polymorphism. In logistic regression analysis, ACPA predicted RA-development independent of PTPN22, while the PTPN22 polymorphism had no independent effect. In HLA-DRB1 shared epitope positive, ACPA-positive UA patients, ACPA-levels were significantly increased in PTPN22 1858T allele carriers compared with non-1858T carriers.

CONCLUSIONS

In this Dutch cohort of UA-patients, the PTPN22 1858T allele does not markedly improve individual decision-making to predict RA-development over ACPA alone, but it is associated with higher ACPA-levels.