A vitamin D3 analog augmented interleukin-8 production by human monocytic cells in response to various microbe-related synthetic ligands, especially NOD2 agonistic muramyldipeptide

Advancement of Traditional Chinese Medicine in Regulation of Intestinal Flora: Mechanism-based Role in Disease Management

Intestinal microecology is the largest and most complex human microecology. The intestinal microflora plays an important role in human health. Imbalance of intestinal microflora contributes to the occurrence and development of many diseases. Recently, the treatment of human diseases by regulating intestinal microflora has become a research topic of interest. Traditional Chinese medicine considers the whole human body as the central concept in disease treatment strategies. It advocates maintaining the coordination and balance of the functions of various organs and systems of the human body, including the intestinal microflora. Traditional Chinese medicine improves the metabolism and immune function of the human body by regulating the intestinal microflora. The intestinal microflora could trigger pharmacological activity or reduce toxicity of drugs through regulating metabolism, which enables traditional Chinese medicine formulations to exert their best therapeutic effects. This review summarized the relationship between the intestinal microflora and digestive system, tumors, and other diseases. Furthermore, the role of traditional Chinese medicine in the treatment of tumors, and other diseases is discussed. The relationship among traditional Chinese medicine and the common intestinal microflora, pathogenesis of human diseases, and effective intervention methods were elaborated. In addition, we explored the research progress of traditional Chinese medicine in the treatment of various human diseases by regulating intestinal microflora to provide new treatment concepts. There is a close relationship between traditional Chinese medicine and the intestinal microflora. Traditional Chinese medicine formulations contribute to maintain the natural balance of the intestinal tract and the intestinal microflora to achieve treatment effects. This paper summarizes the mechanism of action of traditional Chinese medicine formulations in regulating the intestinal microflora in the prevention and treatment of various diseases. Furthermore, it summarizes information on the application of the interaction between traditional Chinese medicine preparations and the regulation of intestinal microflora in the treatment of common human diseases. Intestinal microflora plays a key role in traditional Chinese medicine in maintaining the natural balance of physiology and metabolism of human body. It will provide a theoretical basis for the traditional Chinese medicine preparations in the prevention and treatment of common human diseases, and simulate future research on this aspect.

Effects of vitamin D supplementation on blood markers in ulcerative colitis patients: a systematic review and meta-analysis

OBJECTIVE

Observational studies have shown that vitamin D levels are inversely related to ulcerative colitis activity, yet evidence from population interventions remains inconsistent. We conducted a systematic review and meta-analysis of randomized-controlled trials to clarify the effect of vitamin D on blood markers in patients with ulcerative colitis.

METHODS

The PubMed, Cochrane Library, Embase, CNKI, VIP, and Wanfang databases were searched for studies published before June 2020. Information was collected regarding serum vitamin D levels, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), and Ca (calcium), and parathyroid hormone (PTH), and ulcerative colitis disease activity index (UCDAI) research data.

RESULTS

Seven studies (n = 539) were included in the meta-analysis. Vitamin D supplementation resulted in significant improvements in the serum vitamin D levels (standardized mean difference (SMD) = 0.69, 95% CI (0.36, 1.03), P < 0.001), ESR (weighted mean difference (WMD) = - 1.10, 95% CI (- 1.97, - 0.24), P = 0.01), CRP (SMD = - 0.43, 95% CI (- 0.67, - 0.20), P = 0.0003), and Ca (SMD = 0.92, 95% CI (0.09, 1.74), P = 0.03) but not in other outcomes. According to subgroup analysis, supplementation with vitamin D at a dose of ≥ 300,000 IU/day can improve serum vitamin D levels. Supplementation with a sufficient dose of vitamin D in a short period of time can also improve serum vitamin D levels. According to GRADE method evaluation, the evidence quality was classified as low for the Serum Vitamin D Level and ESR, and very low for the CRP, PTH, Ca, and UCDAI.

CONCLUSIONS

Compared with placebo control interventions, vitamin D supplementation seemed to be an effective intervention for patients with ulcerative colitis. Different doses of vitamin D and durations of intervention produce different effects. However, due to the limitation of the quality of the included studies, the above conclusions still need to be verified by more high-quality studies and weak clinical recommendations.

Effect of high doses of vitamin D supplementation on dengue virus replication, Toll-like receptor expression, and cytokine profiles on dendritic cells

Dengue, caused by dengue virus (DENV) infection, is a public health problem worldwide. Although DENV pathogenesis has not yet been fully elucidated, the inflammatory response is a hallmark feature in severe DENV infection. Although vitamin D (vitD) can promote the innate immune response against virus infection, no studies have evaluated the effects of vitD on DENV infection, dendritic cells (DCs), and inflammatory response regulation. This study aimed to assess the impact of oral vitD supplementation on DENV-2 infection, Toll-like receptor (TLR) expression, and both pro- and anti-inflammatory cytokine production in monocyte-derived DCs (MDDCs). To accomplish this, 20 healthy donors were randomly divided into two groups and received either 1000 or 4000 international units (IU)/day of vitD for 10 days. During pre- and post-vitD supplementation, peripheral blood samples were taken to obtain MDDCs, which were challenged with DENV-2. We found that MDDCs from donors who received 4000 IU/day of vitD were less susceptible to DENV-2 infection than MDDCs from donors who received 1000 IU/day of vitD. Moreover, these cells showed decreased mRNA expression of TLR3, 7, and 9; downregulation of IL-12/IL-8 production; and increased IL-10 secretion in response to DENV-2 infection. In conclusion, the administration of 4000 IU/day of vitD decreased DENV-2 infection. Our findings support a possible role of vitD in improving the innate immune response against DENV. However, further studies are necessary to determine the role of vitD on DENV replication and its innate immune response modulation in MDDCs.

Vitamin D and toll like receptors

It has been demonstrated that vitamin D (VD) significantly modulates immune responses. Toll like receptors (TLRs) are the main innate immunity receptors which are expressed on the cell membrane and intracellular vesicles and recognize several pathogen associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) to induce immune responses. Based on the important roles played by TLRs in physiologic and pathologic functions of immune responses and due to the immunomodulatory functions of VD, it has been hypothesized that VD may present its immunomodulatory functions via modulation of TLRs. This review article collates recent studies regarding the interactions between VD and TLRs and discussed the controversial investigations.

Nod2: A Critical Regulator of Ileal Microbiota and Crohn's Disease

The human intestinal tract harbors large bacterial community consisting of commensal, symbiotic, and pathogenic strains, which are constantly interacting with the intestinal immune system. This interaction elicits a non-pathological basal level of immune responses and contributes to shaping both the intestinal immune system and bacterial community. Recent studies on human microbiota are revealing the critical role of intestinal bacterial community in the pathogenesis of both systemic and intestinal diseases, including Crohn’s disease (CD). NOD2 plays a key role in the regulation of microbiota in the small intestine. NOD2 is highly expressed in ileal Paneth cells that provide critical mechanism for the regulation of ileal microbiota through the secretion of anti-bacterial compounds. Genome mapping of CD patients revealed that loss of function mutations in NOD2 are associated with ileal CD. Genome-wide association studies further demonstrated that NOD2 is one of the most critical genetic factor linked to ileal CD. The bacterial community in the ileum is indeed dysregulated in Nod2-deficient mice. Nod2-deficient ileal epithelia exhibit impaired ability of killing bacteria. Thus, altered interactions between ileal microbiota and mucosal immunity through NOD2 mutations play significant roles in the disease susceptibility and pathogenesis in CD patients, thereby depicting NOD2 as a critical regulator of ileal microbiota and CD.

Calcitriol Suppressed Inflammatory Reactions in IL-1β-Stimulated Human Periodontal Ligament Cells

Vitamin D has important roles on control of calcium and phosphate levels in the body. However, the role of vitamin D on the pathogenesis of periodontal disease is still uncertain. Therefore, we examined the effect of the hormonal form of vitamin D, calcitriol, on inflammatory responses of human periodontal ligament cells (HPDLC). We detected vitamin D receptor expression in non-stimulated HPDLC. Calcitriol inhibited interleukin (IL)-6, IL-8, CC chemokine ligand (CCL) 20, CXC chemokine ligand (CXCL) 10, and matrix metalloproteinase (MMP)-3 release from IL-1β-stimulated HPDLC. Tissue inhibitor of metalloproteinase (TIMP)-1 production did not change by calcitriol. Moreover, we found c-jun N-terminal kinase (JNK) phosphorylation and IκB-α degradation in IL-1β-stimulated HPDLC were inhibited by calcitriol, and JNK and nuclear factor (NF)-κB inhibitors could decrease IL-6, IL-8, CCL20, CXCL10, and MMP-3 productions in IL-1β-treated HPDLC. These findings suggest that vitamin D could modulate inflammatory response in periodontal tissues.

Down-regulation of IL-8 by high-dose vitamin D is specific to hyperinflammatory macrophages and involves mechanisms beyond up-regulation of DUSP1

BACKGROUND AND PURPOSE

There is current interest in vitamin D as a potential anti-inflammatory treatment for chronic inflammatory lung disease, including cystic fibrosis (CF). Vitamin D transcriptionally up-regulates the anti-inflammatory gene DUSP1, which partly controls production of the inflammatory chemokine IL-8. IL-8 is overabundant in CF airways, potentially due to hyperinflammatory responses of CF macrophages. We tested the ability of vitamin D metabolites to down-regulate IL-8 production in CF macrophages.

EXPERIMENTAL APPROACH

CF and healthy monocyte-derived macrophages (MDM) were treated with two vitamin D metabolites, 25-hydroxyvitamin D3 (25OHD3 ) and 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ), or paricalcitol, synthetic analogue of 1,25(OH)2 D3 . 25OHD3 was tested at doses of 25-150 nM, whereas 1,25(OH)2 D3 and paricalcitol at doses of up to 100 nM. IL-8 was stimulated by bacterial virulence factors. As potential anti-inflammatory mechanism of vitamin D metabolites, we assessed up-regulation of DUSP1.

KEY RESULTS

MDM from patients with CF and some healthy donors showed excessive production of stimulated IL-8, highlighting their hyperinflammatory phenotype. Vitamin D metabolites down-regulated stimulated IL-8 only in those hyperinflammatory MDM, and only when used at high doses (>100 nM for 25OHD3 , or >1 nM for 1,25(OH)2 D3 and paricalcitol). The magnitude of IL-8 down-regulation by vitamin D metabolites or paricalcitol was moderate (∼30% vs. >70% by low-dose dexamethasone). Transcriptional up-regulation of DUSP1 by vitamin D metabolites was seen in all tested MDM, regardless of IL-8 down-regulation.

CONCLUSIONS AND IMPLICATIONS

Vitamin D metabolites and their analogues moderately down-regulate IL-8 in hyperinflammatory macrophages, including those from CF. This down-regulation appears to go through DUSP1-independent mechanisms.

Dendritic cells generated in the presence of vitamin D3 and stimulated with lipopolysaccharide secrete IL-8, IL-1β, IL-10 and induce relatively low levels of CD4+CD25hiFoxp3+ T cells

INTRODUCTION

Vitamin D3 (VD3) has been described as a modulator of immune system cells, including dendritic cells (DC). Previous studies have shown its importance in in vitro generation of tolerogenic DC, which have a similar function and phenotype to that of CD141 dermal DCs that produce IL-10 and induce (LTreg) CD4+ T regulator cells. 

OBJECTIVE

This paper presents a study that compares the phenotype and cytokines produced by DC generated in presence and absence of VD3, which were matured with lipopolysaccharide (LPS), and their ability to induce LTreg from naïve allogeneic CD4+ T cells. 

MATERIALS AND METHODS

In order to compare them, peripheral blood mononuclear cells were isolated to select monocytes CD14+ T cells and differentiate them in vitro from DC in the presence and absence of VD3, and to mature them with LPS. Phenotype and cytokine levels were also analyzed in the culture supernatants. Dendritic cells were then co-cultured with naïve allogeneic CD4+ T cells and the frequencies of LTreg were determined (naïve-activated). 

RESULTS

The results showed that unstimulated DC generated with VD3 kept the CD14. When activated with LPS, they expressed lower levels of C83, CD83 and CD86; HLA-DR; higher amounts of IL-1β, IL-8, IL-10, and tended to lessen IL-6, IL-12p70 and TGF-β1, compared to DCs not treated with VD3. The frequency of naïve LTreg was similar, although immature DC generated with VD3 tended to induce activated LTregs. 

CONCLUSION

Based on these results, it is possible to conclude that DCs generated with VD3 and treated with LPS presented a 'semi-mature' phenotype, and were able to secrete pro-inflammatory and anti-inflammatory cytokines. Besides, they did not increase their capacity to promote the polarization of naïve allogenic CD4+ T cells towards LTregs.

Primary 1,25-dihydroxyvitamin D3 response of the interleukin 8 gene cluster in human monocyte- and macrophage-like cells

Genome-wide analysis of vitamin D receptor (VDR) binding sites in THP-1 human monocyte-like cells highlighted the interleukin 8 gene, also known as chemokine CXC motif ligand 8 (CXCL8). CXCL8 is a chemotactic cytokine with important functions during acute inflammation as well as in the context of various cancers. The nine genes of the CXCL cluster and the strong VDR binding site close to the CXCL8 gene are insulated from neighboring genes by CCCTC-binding factor (CTCF) binding sites. Only CXCL8, CXCL6 and CXCL1 are expressed in THP-1 cells, but all three are up-regulated primary 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) target genes. Formaldehyde-assisted isolation of regulatory elements sequencing analysis of the whole CXCL cluster demonstrated 1,25(OH)₂D₃-dependent chromatin opening exclusively for the VDR binding site. In differentiated THP-1 cells the CXCL8 gene showed a 33-fold higher basal expression, but is together with CXCL6 and CXCL1 still a primary 1,25(OH)₂D₃ target under the control of the same genomic VDR binding site. In summary, both in undifferentiated and differentiated THP-1 cells the genes CXCL8, CXCL6 and CXCL1 are under the primary control of 1,25(OH)₂D₃ and its receptor VDR. Our observation provides further evidence for the immune-related functions of vitamin D.

Synergy between vitamin D(3) and Toll-like receptor agonists regulates human dendritic cell response during maturation

Human dendritic cells (DC) can be differentiated from blood monocytes in the presence of GM-CSF and IL-4 and matured by lipopolysaccharide (LPS). Vitamin D₃ inhibits the maturation of human DC measured by changes in surface expression of HLA-DR, CD14, CD40, CD80, CD83, and CD86. We here examine the function of vitamin D₃ during DC maturation. One of the earliest changes to LPS-induced maturation was an increase in CD83 expression. Vitamin D₃ inhibited the increase in expression of HLA-DR, CD40, CD80, CD83, and CD86 and the decrease in expression of CD14, which was paralleled morphologically by vitamin D₃-induced inhibition of dendritic cell differentiation. Vitamin D₃ acted in synergy with the TLR agonists LPS and peptidoglycan (PGN) in inducing IL-6, IL-8, and IL-10, whereas vitamin D₃ completely inhibited LPS-induced secretion of IL-12. The synergy occurred at concentrations where neither vitamin D₃ nor the TLR agonists alone induced measurable cytokine secretion. Both LPS and PGN enhanced the level of the vitamin D₃ receptor (VDR). Taken together, these data demonstrated that vitamin D₃ and TLR agonists acted in synergy to alter secretion of cytokines from human DC in a direction that may provide an anti-inflammatory environment.