From Molecules to Microbes: Tracing Cutaneous T-Cell Lymphoma Pathogenesis through Malignant Inflammation.

The etiology of CTCL is a subject of extensive investigation. Researchers have explored links between CTCL and environmental chemical exposures, such as aromatic hydrocarbons (eg, pesticides and benzene), as well as infectious factors, including various viruses (eg, human T-lymphotropic virus [HTLV]-I and HTLV-II) and bacteria (eg, Staphylococcus aureus). There has been growing emphasis on the role of malignant inflammation in CTCL development. In this review, we synthesize studies of environmental and infectious exposures, along with research on the aryl hydrocarbon receptor and the involvement of pathogens in disease etiology, providing insight into the pathogenesis of CTCL.

The skin microbiome stratifies patients with cutaneous T cell lymphoma and determines event-free survival.

Mycosis fungoides (MF) is the most common entity of Cutaneous T cell lymphomas (CTCL) and is characterized by the presence of clonal malignant T cells in the skin. The role of the skin microbiome for MF development and progression are currently poorly understood. Using shotgun metagenomic profiling, real-time qPCR, and T cell receptor sequencing, we compared lesional and nonlesional skin of 20 MF patients with early and advanced MF. Additionally, we isolated Staphylococcus aureus and other bacteria from MF skin for functional profiling and to study the S. aureus virulence factor spa. We identified a subgroup of MF patients with substantial dysbiosis on MF lesions and concomitant outgrowth of S. aureus on plaque-staged lesions, while the other MF patients had a balanced microbiome on lesional skin. Dysbiosis and S. aureus outgrowth were accompanied by ectopic levels of cutaneous antimicrobial peptides (AMPs), including adaptation of the plaque-derived S. aureus strain. Furthermore, the plaque-derived S. aureus strain showed a reduced susceptibility towards antibiotics and an upregulation of the virulence factor spa, which may activate the NF-κB pathway. Remarkably, patients with dysbiosis on MF lesions had a restricted T cell receptor repertoire and significantly lower event-free survival. Our study highlights the potential for microbiome-modulating treatments targeting S. aureus to prevent MF progression.

Modulation of the skin microbiome in cutaneous T-cell lymphoma delays tumour growth and increases survival in the murine EL4 model.

Cutaneous T-cell lymphomas (CTCL) are a group of lymphoproliferative disorders of skin-homing T cells causing chronic inflammation. These disorders cause impairment of the immune environment, which leads to severe infections and/or sepsis due to dysbiosis. In this study, we elucidated the host-microbial interaction in CTCL that occurs during the phototherapeutic treatment regime and determined whether modulation of the skin microbiota could beneficially affect the course of CTCL. EL4 T-cell lymphoma cells were intradermally grafted on the back of C57BL/6 mice. Animals were treated with conventional therapeutics such as psoralen + UVA (PUVA) or UVB in the presence or absence of topical antibiotic treatment (neomycin, bacitracin, and polymyxin B sulphate) as an adjuvant. Microbial colonisation of the skin was assessed to correlate with disease severity and tumour growth. Triple antibiotic treatment significantly delayed tumour occurrence (p = 0.026), which prolonged the survival of the mice (p = 0.033). Allocation to phototherapeutic agents PUVA, UVB, or none of these, along with antibiotic intervention, reduced the tumour growth significantly (p = 0.0327, p ≤ 0.0001, p ≤ 0.0001 respectively). The beta diversity indices calculated using the Bray-Curtis model showed that the microbial population significantly differed after antibiotic treatment (p = 0.001). Upon modulating the skin microbiome by antibiotic treatment, we saw an increase in commensal Clostridium species, e.g., Lachnospiraceae sp. (p = 0.0008), Ruminococcaceae sp. (p = 0.0001)., Blautia sp. (p = 0.007) and a significant reduction in facultative pathogens Corynebacterium sp. (p = 0.0009), Pelomonas sp. (p = 0.0306), Streptococcus sp. (p ≥ 0.0001), Pseudomonas sp. (p = 0.0358), and Cutibacterium sp. (p = 0.0237). Intriguingly, we observed a significant decrease in Staphylococcus aureus frequency (p = 0.0001) but an increase in the overall detection frequency of the Staphylococcus genus, indicating that antibiotic treatment helped regain the microbial balance and increased the number of non-pathogenic Staphylococcus populations. These study findings show that modulating microbiota by topical antibiotic treatment helps to restore microbial balance by diminishing the numbers of pathogenic microbes, which, in turn, reduces chronic inflammation, delays tumour growth, and increases survival rates in our CTCL model. These findings support the rationale to modulate the microbial milieu during the disease course of CTCL and indicate its therapeutic potential.

Infectious agents in cutaneous T-cell lymphoma.

Infectious agents have long been suspected as potential causative agents in cutaneous T-cell lymphoma (CTCL). Tissues of patients with CTCL have been evaluated for evidence of infection with a number of agents, including Staphylococcus aureus, retroviruses, and herpesviruses. These studies have failed to reveal a consistent association of CTCL with investigated agents. However, there is substantial evidence suggesting a potential role of a yet unidentified virus in CTCL. This article will review the findings of studies exploring potential roles of infectious agents in CTCL. In addition, we investigated CTCL tissues for evidence of infection with Merkel cell polyomavirus, a novel polyomavirus that was recently discovered as a probable carcinogenic agent in Merkel cell carcinoma. Cutaneous lesions demonstrating mycosis fungoides were stained with a monoclonal antibody against the Merkel cell polyomavirus T antigen, along with appropriate positive and negative controls. Immunohistochemical stains produced negative results in all examined mycosis fungoides specimens. These findings, which suggest a lack of association of CTCL with Merkel cell polyomavirus, add to the current body of knowledge regarding infectious agents and CTCL.

Prevalence and treatment of Staphylococcus aureus colonization in patients with mycosis fungoides and Sézary syndrome.

BACKGROUND: Mycosis fungoides (MF) and Sézary syndrome (SS), variants of cutaneous T-cell lymphoma, may arise from antigen-driven clonal expansion and accumulation of helper-memory T cells. Superantigens from Staphylococcus aureus can stimulate T cells. OBJECTIVES: (i) To determine the prevalence of S. aureus carriage in nares and skin in patients with MF/SS compared with historical rates in other conditions. (ii) To determine whether eradication of S. aureus carriage is associated with clinical improvement. Methods Skin and nares cultures were performed prospectively. Patients with positive nares and skin cultures were treated with oral antibiotics and intranasal mupirocin 2% and samples were taken for reculturing at 3 days, 4 weeks and 8 weeks. An exact binomial test was used to compare the carriage rates among different groups. RESULTS: Among 106 patients with MF/SS, 67 (63%) had skin colonization and 57 (54%) had nasal colonization. Staphylococcus aureus was isolated from 44 patients, 33 (31%) each from skin and nares. Colonization was highest in erythrodermic SS (48%), similar to atopic dermatitis (64%), and lowest in MF without erythroderma (26%), psoriasis (21%), and the general population (10%). Oral and topical antibiotics eradicated S. aureus colonization in nares in 28 of 33 (85%) patients and in MF skin lesions in 30 of 33 (91%) patients at 4-8 weeks, with rapid clinical improvement seen in 58% of S. aureus-colonized patients. CONCLUSIONS: Staphylococcal carriage in nares and skin lesions of patients with MF is similar to that in atopic dermatitis. Eradication of staphylococci from the skin is possible with treatment and was associated with clinical improvement.

Cutaneous T-cell lymphoma and Staphylococcus aureus colonization.

BACKGROUND: Bacterial infections are a common complication of cutaneous T-cell lymphoma (CTCL). The most common pathogen of cutaneous infections in CTCL patients is Staphylococcus aureus. OBJECTIVE: The purpose of this study was to assess S aureus colonization rates among CTCL subjects compared to control subjects. METHODS: Fifty subjects with CTCL, 25 psoriasis control subjects, and 25 healthy control subjects were included in this study. Culture swabs were obtained from nares and lesional skin or normal skin in the healthy controls. RESULTS: S aureus colonization rates were 44% in CTCL subjects, 48% in psoriasis subjects, and 28% in healthy control subjects (P = .29). LIMITATIONS: The sample size was small, and the exclusion criteria resulted in an underestimation of the colonization rate. CONCLUSION: There was a trend for higher methicillin-sensitive S aureus colonization in the CTCL group compared with healthy control subjects. S aureus colonization may be directly related to body surface area of CTCL.

Decolonization of Staphylococcus aureus in Healthcare: A Dermatology Perspective.

The bacterium Staphylococcus aureus is responsible for significant morbidity, mortality, and financial burden in healthcare. It easily colonizes susceptible patients and can cause recurrent infections, especially in populations at risk. In addition to treating sequelae of infections, there is a growing body of literature aimed at decolonizing susceptible patients in order to prevent infection and also to prevent spread. Such strategies are widely employed in surgical, intensive care, and hospitalist fields. Staphylococcus aureus involvement has been implicated in the pathogenesis and persistence of many dermatologic diseases that are treated in the outpatient setting. This review serves to summarize current evidence for the management of Staphylococcus aureus colonized patients, as well as the evidence available for decolonization. We further characterize the role that colonization may play in atopic dermatitis, recurrent infections, hand eczema, cutaneous T-cell lymphoma, and also in surgical infections after Mohs surgery.

Karyotypic derivation of H9 cell line expressing human immunodeficiency virus susceptibility.

BACKGROUND: The T-cell lymphoma HUT78 cell line and the H9 clone of the CD4-positive HT cell line, derived from HUT78, are known to be genetically identical on the basis of allozyme (allelic isozyme) patterns and DNA fingerprinting, but the chromosome compositions of these cell lines have not been determined. The HT cell line and its H9 clone carry susceptibility to the human immunodeficiency virus (HIV). PURPOSE: The purpose of this study was to examine specific chromosome changes linking the expression of the HIV susceptibility that is unique to H9 cells by characterizing the karyotypes of the HUT78 and the H9 cell lines, by comparing chromosome differences between these lines, and by evaluating the relationships between them. METHODS: Air-dried chromosome slides were prepared, and the fast Giemsa-trypsin method was used to delineate G-bands. The numerical distribution of chromosomes from the two cell lines was determined, and complete chromosome analysis in 47 HUT78 metaphases and 21 H9 metaphases with discernible G-banding was used to specify the modal karyotypes of each cell line. RESULTS: Both cell lines had complex karyotypes that contained 47%-65% structurally modified marker chromosomes. The distribution of numbers of chromosomes in HUT78 cultures was broad. There were two distinct modal numbers of chromosomes at 42 and 43 and at 73, resulting from the presence of three actively growing sublines: two hypodiploid (1s) sublines (HUT78/1sA and HUT78/1sB) and a hypertriploid (2s) subline (HUT78/2s), respectively. HUT78/1sA and HUT78/1sB differed by five reciprocal chromosome replacements, and HUT78/2s had double copies of most of the chromosomes in 1s cells. H9 and HUT78/2s had had 21 matching markers, 10 of which were paired; contained 21 chromosomes with the same number of copies; consistently lacked eight homologous normal chromosomes; and showed close modal numbers of chromosomes at 69 and 73, respectively. CONCLUSIONS: Derivation of the 2s subline from the 1s subline by polyploidization is apparent. All lines apparently had the same progenitor cell population, and HUT78/2s represents an intermediate linking HUT78/1s to H9. IMPLICATIONS: These data should be useful for studying specific chromosome changes linking the expression of the HIV susceptibility unique to H9 cells. Karyologic studies such as those presented here can provide data (a) to clearly identify the clonal cell population of a subline, (b) to examine relationships among sublines of the same progenitor, and (c) to provide a clue that may link a subtle chromosome change to a phenotypic expression.

Association between Sézary T cell-activating factor, Chlamydia pneumoniae, and cutaneous T cell lymphoma.

Sézary T cell-activating factor (SAF) was originally defined as an inducer of functional interleukin-2 (IL-2) receptors on normal and malignant T cells in patients suffering from Sézary syndrome. In fact, a combination of SAF and IL-2 stimulated the propagation of T cell lines from the peripheral blood mononuclear cells (PBMC) of those patients, with approximately one third of those cell lines containing the predominant malignant clone as determined via cytogenetic and/or T cell receptor gene rearrangement analysis. Although the primary source of SAF was mitogen-stimulated PBMC of a patient with Sézary syndrome, we were unable to isolate the gene encoding SAF from eukaryotic libraries. However, we observed SAF activity in the cytoplasm of one of the malignant cell lines in a complex containing RNA and DNA. This observation led us to consider the possibility that SAF is not of eukaryotic origin. Intracellular pathogens replicate in the cytoplasm of host cells and contain proteins, DNA, and RNA. Using a panel of antichlamydial antibodies with confirmation from polymerase chain reaction primers, we found that most patients with mycosis fungoides were positive for these determinants. Immunoelectron microscopy and protein blotting further confirmed antibody reactivity. We showed that Chlamydia pneumoniae were capable of infecting normal human keratinocytes in culture. We also demonstrated that C. pneumoniae antigen expression was associated with active disease because these determinants were not expressed after psoralen and ultraviolet A therapy. We hypothesize that chronic infection by C. pneumoniae leads to expansion of C. pneumoniae-specific T cells, thereby potentiating the development of cutaneous T cell lymphoma.

Enterococcal eschars in cutaneous T-cell lymphoma tumors: a distinct clinical entity.

Cutaneous T-cell lymphomas (CTCL) are extranodal non-Hodgkin's T-cell lymphomas that present in the skin, the most common form being mycosis fungoides. The progression of disease is associated with acquired immunodeficiency and increased susceptibility to infections. Ten CTCL patients presented with dark brown to black eschars overlying ulcerated tumors that cultured positive for Enterococcus and healed with appropriate antibiotic therapy. Enterococcal infections in CTCL tumors may be recognized as a distinct clinical entity requiring specific intervention.

Retroviruses and cutaneous T-cell lymphoma.

Since the discovery of the first human retrovirus, HTLV-I, and its etiologic role in ATL, the search for a retrovirus and its role in the development and progression of CTCL has been vigorously pursued and debated. Current studies in CTCL have evaluated serum antibodies to retroviral proteins, electron microscopy to identify viruslike particles, and Southern blot analysis and PCR amplification to detect proviral DNA sequences. There have been inconsistent findings within and between a variety of studies, emphasizing the need for critical evaluation of experimental methods and their potential shortcomings. Several interesting observations have included (1) serologic evidence of HTLV-I infection in a small subset of CTCL patients, (2) cloning of a deleted HTLV-I proviral genome from a B-cell line established from the peripheral blood of a CTCL patient, (3) detection of retrovirus in Langerhans cells and B cells, and (4) molecular evidence for the presence of an HTLV-I-like retrovirus. By viewing CTCL as a model of tumor progression, mechanisms by which retroviruses play a role in the development and progression of CTCL are facilitated. Future studies will need to correlate the detection of proviral sequences and the nature of a retroviral infection with specific cell types and stage of disease and determine if these findings demonstrate a causal role in CTCL or a secondary phenomenon due to CTCL-associated immunosuppression. It is likely that new data will be reported between the writing of this article and the time of publication; however, the currently available data reviewed in this article do not provide conclusive evidence that retroviruses play a primary etiologic role in CTCL.

Role of infectious agents in cutaneous T-cell lymphoma: facts and controversies.

The etiology of cutaneous T-cell lymphoma (CTCL) remains unknown, with potential infectious causes having been explored. This contribution evaluates the evidence suggesting an infectious etiology and pathogenesis of the disease, characterizes the relationships between various specific pathogens and CTCL, and discusses some of the difficulties in establishing a causal link between infectious agents and CTCL carcinogenesis. Researchers have evaluated CTCL specimens for evidence of infection with a variety of agents, including human T-lymphotropic virus, Epstein-Barr virus, human herpesvirus-8, and Staphylococcus aureus, although other pathogens also have been detected in CTCL. Although there is significant evidence implicating one or more infectious agents in CTCL, studies to date have not linked definitively any pathogen to disease development, and various studies have yielded conflicting results.

Bacterial toxins fuel disease progression in cutaneous T-cell lymphoma.

In patients with cutaneous T-cell lymphoma (CTCL) bacterial infections constitute a major clinical problem caused by compromised skin barrier and a progressive immunodeficiency. Indeed, the majority of patients with advanced disease die from infections with bacteria, e.g., Staphylococcus aureus. Bacterial toxins such as staphylococcal enterotoxins (SE) have long been suspected to be involved in the pathogenesis in CTCL. Here, we review links between bacterial infections and CTCL with focus on earlier studies addressing a direct role of SE on malignant T cells and recent data indicating novel indirect mechanisms involving SE- and cytokine-driven cross-talk between malignant- and non-malignant T cells.