Table 1.

Characteristics of Published Clinical Trials Examining Vitamin D and Inflammation.

Author (Year)	Study Type, Population	Measurements	Results	Conclusion
Brozek et al. (2012) [24]	Factor and cluster analysis of 105 patients undergoing primary curative surgery for adenocarcinomas	Expression of VDR, CYP27B1, CYP24A1 and COX-2 in relation to tumor grade, anatomical location, and gender	Compared to adjacent mucosa mRNA expression in cancerous lesions was ↑ in CYP27B1 (4-fold in low/high grade cancers), CYP24A1 (20-35-fold in low/high grade lesions) and COX-2 (2-fold in high grade cancers) but not VDR; in distal colon tumors CYP27B1 expression 2-fold ↑ in men than women	Antagonism between COX-2 and Vitamin D could be important factor in epithelial colorectal cancer cell growth; differences in COX-2 expression could influence variation in incidence at different anatomical subsites; cancer incidence gender-specific differences correlate with age
Frăţilă & Iliaş (2013) [25]	Retrospective study 2006–2010 80 patients w/ longstanding ulcerative colitis (LUC) dx (42 women, 38 men) 53.5 ± 14.2 years old	Colonoscopy biopsies: 20 high-grade dysplasia (HGD), 20 low grade dysplasia (LGD), 20 regenerative atypia, 20 indefinite for dysplasia; immunohistochemical (IHC) staining applied for Ki-67, clone MIB-1, and anti-COX-2	COX-2 is positive in 72.5% LUC biopsies; LGD and HGD had Ki-67 staining	IHC staining may be used to manage increased colorectal cancer risk in LUC patients
Leedham et al. (2009) [26]	Mutation burden analysis of individual crypts across colitis associated neoplasms	PCR and sequencing analysis to establish individual crypt adenomatous polyposis coli (APC), p53, K-RAS, and 17p loss of heterozygosity mutation burden	Monoclonality observed in most lesions typically from p53 lesion and occasionally K-RAS	p53 mutation was the initiator in the majority of lesions; K-RAS activation found to be gatekeeping mutation
Wang et al. (2014) [27]	Macrophages from COX-2 KO and COXNeo/Neo mice	COX-2 expression and PG expression in the presence and absence of LPS stimulation	1,25-OHD results in dose-dependent inhibition of COX-2 expression and phosphorylation of Akt and IκBα in murine macrophages with and without LPS stimulation	Vitamin D influences inflammation and supplementation could improve chronic inflammatory diseases via targeting THEM4/Akt/NF-κB signaling
Hummel et al. (2014) [16]	Adenocarcinoma cell line COGA-1A culture and treatment	COGA-1A cells treated with 10 nM 1,25-OHD, 100 ng/mL IL-6, 50 ng/mL or combination of for 6, 12, and 24 hrs; total RNA isolation; reverse transcription polymerase chain reaction (RT-PCR)	COGA-1A cells + 1,25-OHD = ↑ VDR expression; IL-6 ↑ CYP24A1 expression 3x; COX-2 and 15-PGH expression “unresponsive” with 1,25-OHD in COGA-1A cells, but TNF-α “highly ↑ COX-2 expression”	TNF-α and IL-6 inhibited vit D expression-activating gene CYP27B1 in COGA-1A cells
Fichera et al. (2007) [28]	Male A/J mice (25 g) AOM/DSS-induced colitis	Vitamin D analog Ro26-2198 (0.01 µg/kg body wt/day x 28 days); severity of colitis assessed via the Disease Activity Index; hematoxylin and eosin colonic sections examined for dysplasia; colonic lysates assessed for c-Myc, COX-2, phosphor-(active) extracellular signal regulated kinase (ERK) via Western blotting	DSS treatment ↑ c-Myc 15-fold, ERK 10-fold, COX-2 2.5-fold Ro26-2198 ↓ proliferative (c-Myc, ERK) and pro-inflammatory (COX-2) signals and dysplasia progression	Vitamin D analog can be considered when treating colitis
Liu et al. (2016) [29]	25-OHD 1α-hydroxylase knockout (Cyp27b1−/−) mice fed high calcium, phosphate, and lactose rescue diet	Body weight, colon length, and colonic histologic structure	Cyp27b1-/- had ↓ bodyweight, colon length, colon length to bodyweight ratio, mucosa thickness and ↑ crypt damage	1,25-OHD may influence colon inflammation and cancer development and progression
Laverny et al. (2010) [30]	Peripheral blood mononuclear cells (PBMC) obtained from IBD patients (21 ulcerative colitis patients, 22 Crohn’s Disease patients) 26 males, 13 females; C57BL/6 mice w/ 3% DSS treatment; cell study	VDR agonist BXL-62 administration; histology; cytokine quantification; RT-PCR	BXL-62 has 3x less calcemic activity, ↓ proinflammatory cytokines in cells of IBD patients, ↑ CYP24A1 expression, ameliorates experimental colitis compared to 1,25-OHD	BXL-62 is a VDR agonist that does not promote hypercalcemia, ↓ in vitro pro-inflammatory cytokines, and may be used as IBD treatment
Li et al. (2015) [31]	Gene therapy (regulate CYP27B1 expression via CD11b+/Gr1+ monocytes) in murine DSS-induced IBD model	Survival rate, weight, colonic structure, mucosal regeneration index, cytokine expression	↑ survival, body weight gain, colon length, mucosal regeneration and ↓ proinflammatory cytokines (TNF-α, IL-1β, IL-6, IL-12, IL-23, Th1 and Th17)	This preliminary evidence of a monocyte-based adoptive CYP27B1 gene therapy in a murine IBD model may lead to novel therapy for autoimmune disease like IBD
Chen et al. (2017) [32]	Genotyping of patients with colonic polyps (n = 144), colon cancer (n = 96), and UC (n = 44) to determine correlations between CYP24A1 SNPs and diseases	Genotyping of four SNPs (rs4809957, rs6068816, rs6091822 and rs8124792) and their association with colonic polyps, colon cancer, and UC	CYP24A1 polymorphisms rs4809957 A/G and rs6068816 C/T were associated with colonic polyps, colon cancer, and UC	rs4809957, rs6068816, rs6091822 and rs8124792 are related to risk of colonic polyps and cancer; the A allele in rs8124792 may indicate colonic polyps and cancer not UC
Stio et al. (2006) [33]	PBMC of IBD patients; KH 1060 (vitamin D analog) treatment	[3H]thymidine incorporation; ELISA kit; VDR levels w/ Western blotting	KH 1060 ↓ PBMC proliferation, ↓ TNF-α, ↑ VDR expression	KH 1060 can be used on IBD patients to ↓ TNF-α
Zhao et al. (2012) [34]	C57BL/6 mice (n = 30), equally divided among 3 groups: 2% DSS treatment, control, and vitamin D	Serum vitamin D levels, Rachmilewitz DAI (disease activity), colonic injury/inflammation; myeloperoxidase (MPO) activity, mesenteric lymph nodes cells (MLNs) and LPMC isolation; immunohistochemistry; immunofluorescence; in vivo/in vitro permeability; TEER measurement; qT-PCR; Western blotting	Serum vitamin D levels were ↓ in DSS group compared to control; DSS damaged mucosal barrier and ↑ colonic inflammation, ↑ weight loss; vitamin D inhibited colonic inflammation, maintained intestinal permeability, preserved colonic structural integrity, prevented DSS-induced tight junction disruption	Vitamin D warrants therapeutic potential against IBD
Strauch et al. (2007) [35]	Female Balb/c mice w/ 3% DSS treatment; ZK191784 (vitamin D analog) 100 μg/kg per day	Histological examination; ELISA of MLNs; RT-PCR; immunohistochemistry	ZK191784 treatment ameliorates acute and chronic DSS-induced colitis, suppresses proinflammatory cytokine secretion by MLNs and primary dendritic cells	Another study by which vitamin D analog is shown to be beneficial against experimental colitis
Verlinden et al. (2013) [36]	DSS-induced colitis in mice; TX527 (vitamin D analog)	Histological examination, transcript levels of proinflammatory cytokines	TX527 ameliorated DSS-colitis symptoms by ↓ diarrhea and bleeding, ↓ mucosal damage, crypt loss, immune cell infiltration, and ↓ proinflammatory cytokines (IL-1, IL-6, IFN-γ and TNF-α)	TX527 suggests therapeutic potential for IBD management
D’Ambrosio et al. (1998) [37]	Cotransfected monocytic RAW264.7 cells with p40 promotor/reporter constructs and expression vectors of VDR and RXR-α	Expression of NF-κB pathway and cytokines following 1,25-OHD	1,25-OH D caused downregulation of NF-κB activation and ↓ in downstream IL-12	1,25-OHD may downregulate IL-12 production via downregulation of NF-kB activation and p40-kB sequence binding
Du et al. (2015) [38]	Cell study (HCT116, Caco-2, SW480) w/ TNF-α ± 1,25-OHD treatment; C57BL/6 mice w/ paricalcitol (vitamin D analog) treatment; Human colonic mucosal biopsies	Histology/immunostaining; Western blotting, RT-PCR, chromatin immunoprecipitation assay, myeloid perioxidase assay	TNF-α ↓ cells’ transepithelial electrical resistance (TER); > 70% VDR ↓ unable to counteract TNF-α activity and maintain TER; 1,25-OHD counteracts NF-κB by suppressing the myosin light chain kinase signaling pathway (MLCK); MLCK pathway activation = ↓ VDR in human biopsies; paricalcitol inhibits MLCK activation, regulates mucosal barrier, and ameliorates colitis in the mouse model	VDR is required to maintain and protect intestinal epithelial barrier
Meeker et al. (2014) [8]	Smad3−/− mice fed w/ maintenance diet, high vitamin D diet (5 IU/g), or vitamin D-deficient (1 IU/g) diet infected with ~2 × 107 CFU Hb in Brucella broth or Brucella broth alone (control)	Helicobacter bilis infection; Fecal polymerase chain reaction; serum vitamin D and calcium; histopathology; immunochemistry; epithelial and lamina propria leukocyte cell samples; Western blotting	↑ vitamin D diet after H. bilis infection = ↑ serum vitamin D w/o affecting calcium levels. ↓ dysplasia, ↓ inflammation (MAPK, NF-κB), ↓ IBD scores	Vitamin D intake suggests reduced colitis symptoms and delay progression to early stage carcinogenesis
Knackstedt et al. (2013) [13]	Female C57BL/6J mice fed normal chow or vitamin D-deficient diet; Acute colitis: 10 mg/kg AOM + 2% DSS treatment Colitis-associated cancer (CAC): 12 mg/kg AOM + 4% DSS treatment	Vitamin D quantification; colitis scoring; immunohistochemistry; protein extraction; immunoblotting; RT-PCR	AOM/DSS-induced acute colitis mice had ↓ body weight, ↑ blood loss, shortened colon, ↓ serum vitamin D compared to control; CAC model had mortality rate between 10–40%, shortened colon, ↓ serum vitamin D, TNF-α upregulated, RXRα and VDR downregulated	Vitamin D-deficient diet leads to increased colitis scores in the mouse model, downregulated RXRα, VDR, and decreased serum vitamin D levels