Gut microbiota analyses of cutaneous T-cell lymphoma patients undergoing narrowband ultraviolet B therapy reveal alterations associated with disease treatment

Abstract

Recent studies have shown a close relationship between cutaneous T-cell lymphoma (CTCL) and its microbiome. CTCL disease progression is associated with gut dysbiosis and alterations in bacterial taxa parallel those observed in immunologically similar atopic dermatitis. Moreover, the microbial profile of lesional skin may predict response to narrowband ultraviolet B (nbUVB), a common skin-directed therapy. However, the relationship between the gut microbiome, an immunologically vital niche, and nbUVB remains unexplored in CTCL. Herein, we performed 16S rRNA sequencing and PICRUSt2 predictive metagenomics on DNA extracted from stool swabs of 13 CTCL patients treated with nbUVB, 8 non-treated patients, and 13 healthy controls. Disease response was assessed with modified Severity Weighted Assessment Tool (mSWAT); of nbUVB-treated patients, 6 improved (decreased mSWAT), 2 remained stable, and 5 worsened (increased mSWAT). Protective commensal bacteria including Lactobacillaceae and Erysipelatoclostridiaceae were significantly less abundant in CTCL patients compared to controls. With treatment, the CTCL gut microbiome exhibited decreased phylogenetic diversity and lower relative abundance of pro-inflammatory Sutterellaceae. Sutterellaceae was also significantly more abundant in patients who worsened, and Eggerthellaceae and Erysipelotrichaceae trended higher in patients who improved. Finally, PICRUSt2 functional predictions based on shifts in abundance of bacterial sequences repeatedly identified alterations in inositol degradation, which plays a key role in host immunomodulation, including inositol phospholipid signaling relevant to T-cell survival and proliferation. Our results bolster the paradigm of gut dysbiosis in CTCL and its functional implications in disease pathogenesis, and further delineate bacterial taxa associated with nbUVB response and with nbUVB treatment itself.

Keywords: cancer; cutaneous T cell lymphoma; gut dysbiosis; inositol; lymphoma; microbiome; phototherapy; skin cancer.

Figure 1

Distinct microbial communities comprise the gut microbiota of CTCL patients following nbUVB treatment, but not before. Black horizontal lines for Shannon diversity violin plots indicate group median. (A, B) There were no differences in α- or β-diversity between HC and the 13 CTCL treated patients pre-nbUVB (Shannon p=0.10, Bray-Curtis p=0.92). (C, D) Post-nbUVB, the 13 treated CTCL patients had significantly lower α-diversity and significant Bray-Curtis dissimilarity when compared to HC (Shannon p=0.0051, Bray-Curtis p=0.040). (E) Treated patients had a significantly lower α diversity post-treatment compared to pre-treatment (Shannon p=0.0024). (F) Community structures were not distinct pre- versus post-treatment (Bray-Curtis p=0.84). (G) There were no differences in α-diversity between R, NR, and HC pre-treatment (R vs NR, Shannon p = 0.53; NR vs HC, p = 0.24; R vs HC, Shannon p = 0.21). (H) There were no differences in community structure between R, NR and HC pre-treatment (Bray-Curtis p = 0.31). (I) There were no differences in α-diversity between R and NR post-treatment, but both had differences in α-diversity post-treatment when compared to HC (R vs NR, Shannon p = 1; NR vs HC, p=0.011; R vs HC, p=0.022). (J) Community structures of R, NR and HC were different from each other post-treatment (Bray Curtis p = 0.038). (K) Relative abundance of bacterial taxa in stool samples at the family level. Relative abundances were categorized into healthy controls, non-treated CTCL patients, nbUVB responders, and nbUVB non-responders. The mean relative abundances for HC, CTCL pre-nbUVB, and CTCL post-nbUVB are shown on the right. ns, not significant, P > 0.05; *: P ≤ 0.05; **: P ≤ 0.01.

Figure 2

Taxon-by-taxon analysis amongst various study groups analyzed. (A) Individual taxa differences between HC (n=26) and CTCL patients, both treated and untreated (n=42). (B) Relative abundance of Sutterellaceae for all treated CTCL patients prior to nbUVB differed from that of patients following nbUVB (n=13). (C) Differences in individual taxa pre- and post-nbUVB between responders (R) (n=12), non-responders (NR) (n=10), and not treated (NT) CTCL patients (n=16)*. In this analysis, NR are defined only as those who had an increase in their mSWAT score.

Figure 3

Regulation of myo-inositol levels and its role in T-cell immune modulation. Based on available literature and our PICRUSt2 analysis, this figure illustrates the proposed model for how myo-inositol and its degradation pathway may be involved in immune regulation. Our gut microbiome results indicate higher levels of P562-PWY (myo-inositol degradation I) in CTCL patients undergoing phototherapy. Notably, 2 enzymes in this pathway were identified as higher in CTCL patients: EC 1.11.18 (inositol 2-dehydrogenase) and EC 4.2.1.44 (myo-inosose-2 dehydratase). Additionally, EC 3.1.4.3 (phospholipase C [PLC]) is lower in patients after nbUVB treatment. Bacterial PLC and is known to promote T-cell activation through its actions on glycosylphosphatidylinositol (GPI) anchors.