5-hydroxytryptophan attenuates imiquimod-induced psoriasiform dermatitis probably through inhibition of IL-17A production and keratinocyte activation.

Psoriasis is a chronic autoimmune disease with keratinocyte activation and lymphocyte infiltration in the skin. Our previous study found that 5-hydroxytryptophan (5(OH)Trp), a tryptophan metabolite, alleviated collagen-induced arthritis and suppressed cytokine production. In this study, we evaluated the effects of 5(OH)Trp in a mouse model for psoriasiform dermatitis, induced by imiquimod (IMQ). We showed that 5(OH)Trp significantly reduced the cumulative scores, epidermal thickness and ki-67 expression in the skin. In addition, 5(OH)Trp decreased local and systemic inflammation. Moreover, 5(OH)Trp significantly inhibited keratinocyte activation with decrease in IL-6 production and p-Erk1/2 and p-STAT3 expression. 5(OH)Trp also inhibited the differentiation of IFN-γ- and IL-17A-expressing CD4+ T cells and related cytokine production (TNF-α, IL-6, IL-17A and IFN-γ) in splenocytes. In conclusion, 5(OH)Trp can inhibit imiquimod-induced psoriasiform dermatitis in mice and inhibit activation in keratinocytes and splenocytes.

Increased prevalence of Sjogren's syndrome in where soils contain high levels of chromium.

Previously, we showed that farm soil levels of chromium were strongly correlated with people's serum chromium levels and an increase (3.6 fold) in both the incidence and prevalence of sicca syndrome in areas where farm soil chromium was high. Because Sjogren's syndrome (SS) is the major disease causing a dry mouth and dry eyes, we aimed in the study to investigate whether these areas with high soil chromium have a high SS prevalence. We used a database from the authority in charge of catastrophic illness certificates. Heavy metal concentrations in farm soils were retrieved from nationwide surveys. We used spatial regression models to study the relationships between the SS prevalence and soil metal concentrations. There were 11,220 people, 1165 men and 10,055 women who received a SS certificate from 2000 to 2011. The SS prevalence was 31 per 105 people, 5.59 for men and 55.01 for women. The highest SS prevalence in Taiwan (53 per 105) was located in an area where farm soils contain the highest amounts of chromium. In contrast, other types of heavy metal did not show such a strong association. In conclusion, the SS prevalence is significantly increased in areas where soils contain high levels of chromium. Chromium is likely a risk for SS.

Tetrathiomolybdate, a copper chelator inhibited imiquimod-induced skin inflammation in mice.

BACKGROUND: Copper is an essential metal for maintenance of many biological functions; however, excessive amount can induce inflammation and oxidative stress. Tetrathiomolybdate (TM) is a copper chelator for treatment of Wilson's disease, and decreased the severity of autoimmune arthritis in mice. OBJECTIVE: In this report, we evaluated the effects of TM in a mouse model for psoriasis. METHODS: Imiquimod-induced psoriasis murine model was used. We applied immunohistochemistry staining and ELISA to determine levels of cytokines in the inflamed skin, splenocytes, and draining lymph nodes. In addition, we used keratinocytes and splenocytes to test the inhibitory effects of TM on cytokine production and activation of transcription factors. RESULTS: Our results showed that TM significantly reduced cumulative scores, epidermis thickness, and ki-67 expression in the inflamed skin. In addition, TM decreased skin cytokine levels and systemic inflammation. Moreover, TM suppressed activation in keratinocytes and splenocytes with reduction in phosphorylation of Erk1/2 and STAT3. CONCLUSION: These findings are strong evidence that TM can inhibit psoriasis in the model.

Cordycepin and a preparation from Cordyceps militaris inhibit malignant transformation and proliferation by decreasing EGFR and IL-17RA signaling in a murine oral cancer model.

Cordyceps militaris (CM) and its active ingredient cordycepin have been reported to inhibit tumor growth, but the mechanisms are not fully understood. This study used a mouse model for oral cancer and a cell line, 4NAOC-1 derived from the model to study the mechanisms. Our results show that a CM preparation (CMP) can significantly inhibit tumor development and malignant transformation in the model. In vitro data indicate that CMP and cordycepin can inhibit 4NAOC-1 cell proliferation, either anchorage-dependent or -independent. Cordycepin can also increase cell apoptosis, and decrease cell mitosis and EGFR signaling. In accordance, CMP treatment can significantly decrease the levels of ki-67 and EGFR signaling molecules in cancer tissues. We also found that the levels of IL-17A in cancer tissues of control mice were significantly increased, and CMP inhibited these levels. IL-17A can stimulate cancer cell proliferation, which can be suppressed by cordycepin. Furthermore, cordycepin can reduce the expression of IL-17RA and its downstream signaling molecules. Moreover, CMP and cordycepin can significantly decrease IL-17A production in vitro and in vivo. Finally, CMP and its ingredients can enhance tumoricidal activities with increase in IFN-γ and TNFα, and decrease PD-L1 expression. In conclusion, CMP and its ingredient cordycepin can inhibit tumor growth and malignant transformation in a mouse model for oral cancer via inhibition of EGFR- and IL-17RA-signaling and enhancement of anti-tumor immunity.

Supplement of 5-hydroxytryptophan before induction suppresses inflammation and collagen-induced arthritis.

BACKGROUND: Evidence is accumulating that a preclinical phase is present before the onset of clinical signs and symptoms of rheumatoid arthritis (RA). This phase represents an important therapeutic window within which interventions can dramatically modulate outcomes. An agent able to prevent RA for high risk individuals in this phase is therefore desired. In this study, we investigated whether tryptophan metabolite, 5-hydroxytryptophan (5-HTP) or 5-methoxytryptophan (5-MTP), can act as such an agent for primary prevention of collagen-induced arthritis (CIA). METHODS: Mouse splenocytes were pretreated with 5-HTP or 5-MTP and activated by anti-CD3 plus anti-CD28 antibodies in vitro. The percentages of interferon-γ (IFNγ)(+)CD4(+) T cells and interleukin-17 (IL-17)(+)CD4(+) T cells were measured by flow cytometry. The production of pro-inflammatory cytokines, serotonin and kynurenine was measured by enzyme-linked immunosorbent assay. A CIA model was used to investigate the in vivo effects of 5-HTP on the prevention of arthritis. RESULTS: 5-HTP decreased the percentages of IFNγ(+)CD4(+) T cells and IL-17(+)CD4(+) T cells and suppressed the production of IL-2, IL-4, IL-6, IL-17, tumor necrosis factor-α (TNFα) and IFNγ in activated splenocytes. 5-HTP administered before induction decreased the disease activities in CIA mice and suppressed the production of TNFα, IL-6 and cyclooxygenase-2 in arthritic joints. 5-HTP also increased serotonin, but decreased kynurenine in the CIA mice. CONCLUSIONS: 5-HTP suppresses inflammation and arthritis through decreasing the production of pro-inflammatory mediators. 5-HTP supplement before induction ameliorates arthritis in a CIA model.