Anti-Psoriatic Effects and IL-22 Targeting Mechanism of Indirubin by Suppressing Keratinocyte Inflammation and Proliferation

Indigo naturalis, which is extracted from the leaves and branches of Baphicacanthus cusia (Nees) Bremek, has traditionally been used to treat psoriasis. The current study aimed to examine a new mechanism of the components of indigo naturalis, including indirubin, indigo, and tryptanthrin. The anti-psoriatic effects were assessed by the proliferation biomarkers (Ki67, K16), cell cycle progression, ROS production, and interleukin profiling (ICAM-1, TNF-α, IL-6, and IL-8) in IL-22-treated HaCaT cells. Among the components, indirubin significantly decreased intracellular ROS production and lowered the production of ICAM-1, TNF-α, and IL-6 in IL-22-treated HaCaT cells. Indirubin, indigo, and tryptanthrin could decrease the proportion of Ki67-positive cells, but only indirubin decreased the proportion of cells entering the S phase and suppressed the expression of cyclin D1 and cyclin E1 in IL-22-treated HaCaT cells. Indirubin significantly suppressed the phosphorylation of STAT3 and ERK. In vivo, IL-22 was intradermally injected into mouse ears for six days and topically treated with 0.1% or 1% indirubin. In the IL-22-injected mice, treatment with indirubin inhibited epidermal hyperplasia. Immunohistochemistry and western blot analysis demonstrated the downregulation of K16 expression in psoriatic lesions. These results suggest that indirubin, which is a major component of indigo naturalis, may have therapeutic potential in an IL-22-induced psoriasis model.

Treatment-refractory ulcerative colitis responsive to indigo naturalis

BackgroundIndigo naturalis (IN) is an herbal medicine that has been used for ulcerative colitis with an unclear mechanism of action. Indigo and indirubin, its main constituents, are ligands of the aryl hydrocarbon receptor (AhR). We assessed the safety, efficacy, and colon AhR activity of IN given orally to patients with treatment-refractory ulcerative colitis. The role of AhR in IN benefit was further evaluated with an AhR antagonist in a murine colitis model.MethodsThis open-label, dose-escalation study sequentially treated 11 patients with ulcerative colitis with either IN 500 mg/day or 1.5 g/day for 8 weeks, followed by a 4-week non-treatment period. The primary efficacy endpoint was clinical response at week 8, assessed by total Mayo score. Secondary endpoints included clinical remission, Ulcerative Colitis Endoscopic Index of Severity, quality of life, and colon AhR activity measured by cytochrome P450 1A1 (CYP1A1) RNA expression.ResultsTen of 11 (91%) patients, including 8/9 (89%) with moderate-to-severe disease, achieved a clinical response. Among these 10 patients, all had failed treatment with 5-aminosalicylic acid, 8 patients with a tumour necrosis factor (TNF)-alpha inhibitor, and 6 patients with TNF-alpha inhibitor and vedolizumab. Five patients were corticosteroid dependent. Clinical response was observed in all five patients who had been recommended for colectomy. Three patients achieved clinical remission. All patients experienced improved endoscopic severity and quality of life. Four weeks after treatment completion, six patients had worsened partial Mayo scores. Four patients progressed to colectomy after study completion. Colon CYP1A1 RNA expression increased 12 557-fold at week 8 among six patients evaluated. No patient discontinued IN due to an adverse event. Concomitant administration of 3-methoxy-4-nitroflavone, an AhR antagonist, in a murine colitis model abrogated the benefit of IN.ConclusionIN is a potentially effective therapy for patients with treatment-refractory ulcerative colitis. This benefit is likely through AhR activation.Trial registration numberNCT02442960.

Prospective feasibility study of indigo naturalis ointment for chemotherapy-induced oral mucositis

ObjectivesIndigo naturalis, a herbal medicine effective against ulcerative colitis, exhibits anti-inflammatory effects and induces interleukin-22-mediated antimicrobial peptide production. Anti-inflammatory activity and the prevention of secondary infection are essential for the management of chemotherapy-induced oral mucositis (CIOM); therefore, we developed an indigo naturalis ointment to be administered topically for CIOM and evaluated its feasibility.MethodsWe performed a single-centre, open-label, prospective feasibility study from March 2017 to December 2018. The key eligibility criteria for the subjects were as follows: (1) receiving chemotherapy for a malignant tumour; (2) grade 1 or 2 CIOM and (3) receiving continuous oral care. The treatment protocol comprised topical indigo naturalis ointment application three times a day for 7 days. The primary endpoint assessed was feasibility. The secondary endpoints assessed were the changes in oral findings, oral cavity pain and safety.ResultsNineteen patients with CIOM were enrolled. The average feasibility (the proportion of prescribed applications that were carried out) observed in this study was 94.7%±8.9% (95% CI 90.5% to 99.0%), which was higher than the expected feasibility. The revised oral assessment guide scores of the mucous membrane domain and total scores were significantly improved. All patients reported a reduction in oral cavity pain, with a median pain resolution duration of 6 days. No serious adverse events were observed.ConclusionsThe indigo naturalis ointment was feasible, and showed the potential for efficacy and safety. Larger randomised controlled trials are needed to further assess the efficacy and safety of indigo naturalis compared with a placebo.Trial registration numberUMIN000024271.

Exploring the Mechanism of Indigo Naturalis in the Treatment of Ulcerative Colitis Based on TLR4/MyD88/NF-κB Signaling Pathway and Gut Microbiota

Background: Clinical trials have proven that indigo naturalis is a candidate drug for treating ulcerative colitis (UC), but its therapeutic mechanism is still unclear.Purpose: This study aimed to evaluate the protective effect and mechanism of indigo naturalis to treat mice with dextran sulfate sodium (DSS)-induced UC.Methods: DSS-induced UC mice were treated with indigo naturalis (200 mg/kg), indigo (4.76 mg/kg), and indirubin (0.78 mg/kg) for 1 week. The anti-UC mechanism of indigo naturalis was studied by pathological section, inflammatory factor, western blot, and 16S rRNA sequencing.Results: According to body weight change, disease activity index, and colon length, indigo naturalis had the strongest anti DSS-induced UC effect, followed by indirubin and indigo. Pathological section showed that indigo naturalis, indigo, and indirubin could reduce the infiltration of inflammatory cells, increase the secretion of intestinal mucus, and repair the intestinal mucosa. Indigo naturalis, indigo, and indirubin could reduce IL-1β,IL-6, and TNF-α by inhibiting TLR4/MyD88/NF-κB signal transduction. Indigo naturalis and indigo could also reduce IgA and IgG both in serum and colon tissue. In addition, indigo naturalis, indigo, and indirubin could adjust the gut microbiota structure of DSS-induced UC mice, reducing the ratio of Firmicutes/Bacteroidetes and increasing the abundance of probiotics.Conclusion: Indigo and indirubin are one of the main anti-UC components of indigo naturalis. INN could regulate intestinal flora, reduce inflammation, repair intestinal mucosa, and improve the physiological status of DSS-induced UC mice and its anti-UC mechanism may be involved in inhibiting TLR4/MyD88/NF-κB signal transduction.

A Comprehensive Review of the Chemistry, Pharmacokinetics, Pharmacology, Clinical Applications, Adverse Events, and Quality Control of Indigo Naturalis

Indigo naturalis (IN), which is derived from indigo plants such as Strobilanthes cusia (Nees) Kuntze, Persicaria tinctoria (Aiton) Spach, and Isatis tinctoria L., has been traditionally used in the treatment of hemoptysis, epistaxis, chest pain, aphtha, and infantile convulsion in China for thousands of years. Clinical trials have shown that the curative effect of IN for psoriasis and ulcerative colitis (UC) is remarkable. A total of sixty-three compounds, including indole alkaloids, terpenoids, organic acids, steroids, and nucleosides, have been isolated from IN, of which indole alkaloids are the most important. Indirubin, isolated from IN, was used as a new agent to treat leukemia in China in the 1970s. Indirubin is also an active ingredient in the treatment of psoriasis. Pharmacological studies have confirmed that IN has inhibitory effects on inflammation, tumors, bacteria, and psoriasis. Indigo, indirubin, tryptanthrin, isorhamnetin, indigodole A, and indigodole C are responsible for these activities. This review provides up-to-date and comprehensive information on IN with regard to its chemistry, pharmacokinetics, pharmacology, clinical applications, adverse events, and quality control. This review may also serve a reference for further research on IN.

Oral Realgar-Indigo Naturalis Formula Plus Retinoic Acid for Acute Promyelocytic Leukemia

Treatment paradigm of acute promyelocytic leukemia (APL) is by no mean the most remarkable story of cancer therapy. Recently, the advent of oral arsenic formulations (oral-arsenic trioxide and Realgar-Indigo Naturalis formula (RIF)) based regimens may provide a therapeutic advance by curing APL with two oral agents. Indeed, the oral RIF plus all-trans-retinoic acid (ATRA) without chemotherapy display highly efficacy in patients with APL. The safety profile of RIF plus ATRA make possible to treat APL patients in a home-based manner during postremission therapy. To our knowledge, RIF was the first commercially available oral arsenic agent approved in China. The RIF plus ATRA regimens are becoming a preferred frontline care for APL in China. In this review, we will discuss the history, current evidences and challengers of RIF-based strategies in APL. More and more APL patients may enjoy a cure with a normal quality-of-life after induction in the near future.