T-cell receptor gene rearrangement in canine mycosis fungoides: further support for a canine model of cutaneous T-cell lymphoma

A Microbiota-Dependent, STAT3-Driven Mouse Model of Cutaneous T-Cell Lymphoma

In recent years, much has been learned about the molecular genetics of cutaneous T-cell lymphomas. Fanok et al. (2018) translate knowledge from systematic genomic and transcriptomic analyses to develop a mouse model that tests the hypothesis that activated STAT3 in CD4⁺ T cells may be a driver of cutaneous T-cell lymphomas. The transgenic mouse that they developed exhibits clinical features of mycosis fungoides, as well as Sezary syndrome, two well-known entities in the cutaneous T-cell lymphoma spectrum. Furthermore, these authors show that TCR engagement and microbiota are required for development of the complete clinical phenotype. This mouse model, which develops progressive disease, provides a new tool to understand cutaneous T-cell lymphoma biology and to potentially test new therapies.

Classification and clinical features in 88 cases of equine cutaneous lymphoma

Equine cutaneous lymphoma is an uncommon disease that can present with variable clinical signs, immunosuppression, and rapid systemic disease progression. Various subtypes of equine lymphoma have been described and classified according to a veterinary adaptation of the World Health Organization classification system, but little data is available regarding the association between lymphoma subtypes and epidemiological criteria and/or clinical outcome. The objective of the current study was to classify previously diagnosed cases of equine cutaneous lymphoma and correlate subtypes with clinical data to investigate epidemiological trends and prognostic implications. Results from the study confirm T-cell–rich, large B-cell lymphoma (TCRLBCL) as the predominant subtype in equine cutaneous lymphoma. Cutaneous T-cell lymphoma (CTCL) was the second most common phenotype in the current study. To the authors’ knowledge, a description of the morphological and immunohistochemical features of CTCL in horses, an epitheliotropic neoplasm similar to the cutaneous epitheliotropic lymphoma variant (mycosis fungoides) observed in human beings and canids, has not been previously described. Less common lymphoma subtypes identified in the study include diffuse large B-cell lymphoma and anaplastic large T-cell lymphoma. Quarter Horses almost exclusively developed TCRLBCL, while the frequency of CTCL was increased significantly in Thoroughbreds compared with other breeds. TCRLBCLs more frequently presented as multiple masses while CTCLs were more often solitary nodules. When multiple regions of the body were affected, 100% of cases were TCRBCL. Finally, there was an observable trend for longer survival in cases of TCRLBCL without local recurrence, suggesting adequate surgical excision may be an effective treatment modality.

The structure and functional analysis of canine T-cell receptor beta region

VDJ recombination is a key process in T-cell receptor (TCR) and immunoglobulin (Ig) molecules development. Comparison of ENSEMBL and GenBank database information revealed major differences in dog T-cell receptor beta (TRB) region annotations. ENSEMBL based genomic alignment of dog TRB sequence with human sequence and annotation showed a very similar structure of TRB. However, there is only one cluster of DJC segments in dogs. In dog, 38 V segments are followed by 1 D segment, 6 J segments and 1 C segment. Like humans and mice, dogs have another V segment opposite in orientation downstream of the C segment. V segments anticipated were analyzed using the RT-PCR and capillary electrophoresis. Thirty-one of them were identified in samples of thymus and spleen RNA and thus believed to be subjected to chromosomal rearrangement and RNA splicing. We identified and analyzed probable structure of canine TCR beta region, which is different when compared to sequences published in GenBank or ENSEMBL databases.

Investigation on the association between atopic dermatitis and the development of mycosis fungoides in dogs: a retrospective case-control study

In human medicine, the relationship between the immunodysregulation observed in atopic dermatitis (AD) and the development of mycosis fungoides (MF) has triggered considerable interest due to the increasing number of patients with MF who have a previous history of AD. The purpose of this retrospective case-control study was to investigate whether dogs diagnosed with MF were more likely to have AD. The records of 96 000 canine patients at the University of Florida were searched. Inclusion criteria were a clinical and histological diagnosis of MF. Dogs admitted to the University of Florida, Veterinary Medical Center during the same time period (1991-2004) without a diagnosis of MF were included as controls. Four controls for each study dog were randomly selected (matched by year of admission). Frequency of AD and other exposure variables were compared among case and control dogs by using conditional logistic regression. Records of 19 dogs with a diagnosis of MF were identified. Five of them (5/19, 26.3%) had previous diagnosis of AD. The odds of having MF was 12 times (OR = 12.54; 95% CI = 1.95-80.39; P < 0.01) higher in dogs with AD than in dogs without AD. In conclusion, this study suggests an association between AD and MF in dogs. Future studies are necessary to confirm this finding and to investigate the pathogenic mechanisms involved in this association.

Molecular methods to distinguish reactive and neoplastic lymphocyte expansions and their importance in transitional neoplastic states

Although lymphoma and leukemia usually can be diagnosed by routine cytology and histology, some cases present a diagnostic challenge for pathologists and clinicians. Often the dilemma lies in determining whether a population of lymphocytes is reactive or neoplastic. We review currently available methods for analyzing lymphocyte populations by immunophenotyping and by identifying clonally rearranged immunoglobulin and T-cell receptor genes and discuss how these tests can be used to clarify such diagnostic dilemmas. We also describe the detection of chromosomal abnormalities and methods on the horizon, such as gene expression profiling, to identify diagnostically useful oncogenes. Finally, we review the emerging concept of transitional neoplastic states, in which reactive lymphocytes transform to neoplastic lymphocytes in the presence of continued antigenic stimulation, such as that caused by infection with Helicobacter pylori. The existence of transitional neoplastic states underscores the need for an array of molecular diagnostic tools that would improve our ability to characterize lymphocyte populations in human and animal patients and enhance early detection of neoplastic lymphocytes such that eradication of the infectious or inflammatory stimulus could lead to cure.

Central nervous system metastasis of a cutaneous epitheliotropic lymphosarcoma in a dog

This report describes an uncommon case of a cutaneous epitheliotropic T-cell lymphosarcoma with central nervous system (CNS) manifestations in a 9-year-old mixed breed German shepherd dog. The animal had a history of sudden blindness, pyrexia and multifocal areas of hyperaemia in the oral mucosa. A biopsy from the muco-cutaneous junction of the lips led to the diagnosis of an epitheliotropic lymphosarcoma and the animal was humanely destroyed. At necropsy, hyperaemia in the oral mucosa was no longer detectable. In the brain, a mass effacing the optic chiasm and invading the hypothalamic area was found; histological examination revealed lymphoid tumour cell infiltration. In the epithelium of the oral mucosa, intra-epithelial lymphoid tumour cells, sometimes arranged in small clusters (Pautrier's microabscesses), in combination with a mild inflammation in the superficial dermis were observed. Skin and brain tumour cells expressed CD3 antigen, indicating their T-cell origin. This is, to our knowledge, the first report of a cutaneous epitheliotropic lymphosarcoma with CNS metastasis in a dog.

An immunophenotypic study of canine leukemias and preliminary assessment of clonality by polymerase chain reaction

There is a relative lack of information in the veterinary literature regarding the immunophenotypes present in canine leukemias. Utilizing a panel of thirty monoclonal antibodies, canine leukemias were assessed by flow cytometry alone or by flow cytometry in combination with immunocytochemical staining of smears. Canine chronic lymphocytic leukemia (CLL) occurred in older dogs (mean age 9.75 years; range 1.5-15 years; n = 73 cases). Blood lymphocyte counts ranged from 15,000 to 1,600,000/microl. Surprisingly, 73% of CLL cases involved proliferation of T lymphocytes (CD3+), and 54% of CLL cases had large granular lymphocyte (LGL) morphology. LGL CLL's were almost exclusively proliferation's of T cells that expressed CD8 and the leukointegrin alphaDbeta2 and more frequently expressed T cell receptor (TCR) alphabeta (69%) than TCRgammadelta (31%). The non-LGL T cell CLL cases (19% of CLL) involved proliferation of TCRalphabeta T cells in which no consistent pattern of CD4 or CD8 expression was found. B cell CLL, based on expression of CD2 or CD79a, comprised 26% of canine CLL cases. These results are in marked contrast to people where greater than 95% of CLL cases involve proliferation of B lymphocytes. Thirty eight (38) acute leukemias were also immunophenotyped. The majority (55%) of these leukemias had a phenotype most consistent with a myeloid origin. Acute LGL leukemias were also observed (7/38), although less commonly than the CLL counterpart. CD34 expression was common in acute, non-LGL leukemias of dogs, both myeloid and lymphoid. In some circumstances, it can be difficult to differentiate a reactive (polyclonal) lymphoid proliferation from a neoplastic (monoclonal) one. Therefore, as an adjunct to phenotypic studies, we have developed a polymerase chain reaction (PCR) based test for assessment of clonality in T cell proliferations. The test amplifies the junction of the variable gamma (Vgamma) and joining gamma (Jgamma) gene segments region of the TCR gamma genes. Preliminary data indicates that our test is effective and is capable of differentiating a neoplastic from a reactive lymphoproliferative process.

Photodynamic therapy in veterinary medicine: current status and implications for applications in human disease

The historical development and published veterinary applications of photodynamic therapy are reviewed. Potential animal models, using naturally-occurring diseases in veterinary patients, for the future development of photodynamic therapy are described.

Blood cell markers

Cytochemistry and immunocytochemistry are important adjunctive technologies to the morphologic characterization of blood cells and hematopoietic neoplasms. Although cytochemistry is briefly discussed, the emphasis of this article is on the clinical application of flow cytometry and leukocyte monoclonal antibodies in veterinary medicine. Classification and significance of immunophenotyping in canine and feline lymphomas and immunodeficiencies such as feline immunodeficiency virus and feline leukemia virus are discussed.

The immunological effect of 8-methoxypsoralen and UVA treatment on murine T-cell leukemia

8-Methoxypsoralen (8-MOP) plus long-wavelength UV radiation (UVA, 320-400 nm) have been used to treat various diseases such as cutaneous T-cell lymphoma, systemic scleroderma, rheumatoid arthritis and rejection of heart transplants. However, the immunological mechanism of this treatment remains unknown. In this report, we investigated the effect of 8-MOP/UVA on the modulation of the immunogenicity of a T-cell leukemia cell line (RL male 1 cells). The results demonstrated that the stimulator function of the in vitro 8-MOP/UVA-treated RL male 1 cells was enhanced in both RL male 1-specific allogeneic and syngeneic immune responses. Furthermore, the enhancement of the immunogenicity of the 8-MOP/UVA-treated RL male 1 cells was found to be strongly associated with the increase of intercellular adhesion molecule-1 expression on these 8-MOP/UVA-treated tumor cells. Therefore, our findings suggested that the alteration of the expression of the immune-related cell surface molecules might be an important effect of 8-MOP/UVA treatment on the elevation of the immunogenicity of the 8-MOP/UVA-treated tumor cells.

Restriction fragment length polymorphism of the T-cell receptor beta-chain gene in dogs

Since T-cells and the T-cell receptor (TCR) play a pivotal role in the response of the immune system, they are a target for pathogenesis studies in immune mediated diseases and have been used to generate markers for T-cell dependent diseases in humans and dogs. TCR rearrangement is generated at the genomic DNA level and can be analyzed by Southern blotting techniques. In the present study this method to detect rearrangement of the TCR beta chain in the dog was critically examined. To search for restriction fragment length differences due to either inherited polymorphism or in diseases with suspected superantigen influence (X-linked severe combined immune deficiency and canine juvenile polyarteritis syndrome) 13 dog families of three different breeds were examined. In addition primary spleen cell cultures, stimulated with either phytohemagglutinin A (PHA) or staphylococcus enterotoxin A (SEA) and B (SEB) were studied. The germline digest pattern of the enzymes Pst I, Sst I, Bgl II, Eco RI and Eco RV were identical in all dogs examined with the exception of one dog with canine juvenile polyarteritis syndrome. In this dog an additional band was found in the Bgl II and Eco RV digestion suggestive of specific TCR rearrangement. Bam HI digestion revealed restriction fragment length polymorphisms (RFLPs) showing Mendelian inheritance. After digestion of the genomic DNA extracted from PHA, SEA or SEB stimulated spleen cells and Southern blot analysis, no differences in fragment patterns between the unstimulated cells and the stimulated cells could be detected. An important point to consider before a specific pattern variation between dogs is classified to be a marker for a specific disease or is used in pathogenesis studies, is the possibility of an inherited RFLP, especially after Bam HI digestion. In such studies the combined examination of the parents and the offspring must be recommended.

Psoralen photobiology: recent advances

Clinical efficacy may arise from psoralen-induced photodamage by the induction of a panoply of biomolecules. In cellular studies with UV or photoactivatable agents, the activation of NF-kappa B, probably the most widely studied transcription factor, occurs after its release from an inhibiting factor, I kappa B. The activation of transcription factors has also been correlated with the UV absorption spectrum of DNA (35). Furthermore, it was shown that the photoadducts do not need to be processed or repaired because transcription factor induction is observed in repair-deficient cells. In these latter cells lower UV doses are required to induce these transcription factors. As a result of transcription factor induction, treated cells may have a greater number of class I molecules on their surface and an altered cytokine profile. It is possible (and likely) that these effects occur in different cells to different extents. The important message is that activational events may occur that could alter the cell's (or cells') ability to regulate a disease process. Many studies have shown that the time frame for this type of damage-induced event may range from seconds to minutes (36). Clearly 8-MOP/UVA-induced events such as those described above could be initiated as the result of a single photochemotherapy session.

Lithium and psoriasis: cytokine modulation of cultured lymphocytes and psoriatic keratinocytes by lithium

The predominant cutaneous side effect of lithium is the exacerbation or aggravation of psoriasis, but the pathogenesis is still unclear. The hyperproliferation of keratinocytes and a dense lesional infiltrate of mononuclear cells are the hallmarks of psoriatic skin lesions. Interactions between keratinocytes and T cells are thought to be one reason for an increased secretion of proinflammatory cytokines and growth factors. To investigate whether lithium influences cytokines of the "psoriatic cytokine network', we established a coculture model with keratinocytes from psoriatic patients and from healthy controls cultured with HUT 78 lymphocytes and measured the cytokine levels of Il-2, Il-6, Il-8, IFN gamma and TGF alpha in the culture supernatants after treatment with lithium. Il-6 levels were slightly elevated in the supernatants obtained from psoriatic and control keratinocyte cultures after lithium treatment, but IFN gamma and Il-2 levels were elevated only in the lithium-treated cocultures with psoriatic keratinocytes. In contrast, these two cytokines were not affected by lithium in HUT 78 monocultures or in cocultures with normal epidermal cells. We also found slightly elevated TGF alpha levels in lithium-treated psoriatic cocultures but not in control cultures. We therefore demonstrated that lithium influences the cell communication of psoriatic keratinocytes with HUT 78 lymphocytes by triggering the secretion of TGF alpha, Il-2 and, massively, IFN gamma. It seems possible that lithium also influences similar parts of the psoriatic cytokine network in vivo.

Equine Cutaneous Lymphoma: A Case Report

Résumé- Les commémoratifs, les symptômes, l'histologie et la réponse au traitement d'un cheval de 15 ans atteint de lymphome cutané sont décrits. La jument présente de multiples nodules cutanés depuis 11 ans. Un diagnostic de lymphome cutané est poséà l'examen histologique de biopsies réalisées 2 fois à 4 ans d'intervalle. Des marquages immunihistochimiques identifient ces cellules comme appartenant à la lignée T. Ceci est la première description du marquage immunophénotypique d'un lymphome cutané chez le cheval. La jument a été traitée par des glucorticoïdes intralésionnels et des progestagènes oraux ce qui a entrainé une régression complète des nodules. Resumen- Describimos la historia clinica y los hallazgos clinicos e histológicos de un caballo de 15 años con un linfoma cutáneo. La yegua tenia una historia clinica de multiples nédules cutáneos en los últimos 11 años. Se diagnosticó un linfoma cutáneo mediante estudio histológico de dos biosias tomadas con unos cuatro años de separación. Tinciones inmunohistoquimicas ulteriores identificaron la linea celular de ünfocitos T. Este es el primer estudio que caracteriza el linfoma equino a nivel inmunofenotipico. La yegua fue tratada con glucocorticoides intralesionales y progestágenos orales, lo que resultó en curación total de los nódulos. Abstract- The history, clinical and histological features and response to treatment of a 15-year-old horse with cutaneous lymphoma are described. The mare had an 11 year history of multiple cutaneous nodules. A diagnosis of cutaneous lymphoma was made on histological examination of biopsy material taken on two separate occasions some 4 years apart. Subsequent immunohistochemical staining identified the cell lineage as T-lymphocytes. This is the first report of immunophenotypic characterisation of cutaneous lymphoma in the horse. The horse was treated with intralesional glucocorticoids and oral progestins, and complete resolution of the nodules resulted.

Immunophenotypic characterization of cutaneous lymphoid neoplasia in the dog and cat

Clinical, histopathological and immunohistochemical findings are presented from a series of cutaneous lymphoid neoplasms including canine epitheliotrophic lymphoma (n = 7), canine non-epitheliotrophic cutaneous lymphoma (n = 10), canine cutaneous plasmacytoma (n = 10) and feline non-epitheliotrophic cutaneous lymphoma (n = 6). Three cases of canine epitheliotrophic lymphoma expressed the CD3 T-lymphocyte marker, but the remainder were negative for this molecule and for a panel of B-cell markers. Non-epitheliotrophic cutaneous lymphoma was shown to be predominantly of T-cell phenotype (CD3+) in the dog (eight of 10 cases) and cat (five of six cases), the remaining cases in both species being of B-cell origin, expressing the gamma heavy chain of immunoglobulin (with or without lambda light chain). One canine non-epitheliotrophic B-cell lymphoma expressed IgG of the IgG2 subclass. Two of the biopsies from dogs with cutaneous plasmacotyoma were shown to express immunoglobulin alpha chain (one with lambda chain) and two neoplasms were positive for immunoglobulin gamma chain (both with lambda chain). One of the latter immunoglobulins was of the IgG4 subclass. In the majority of all cases of cutaneous lymphoid neoplasia examined, there was a local polyclonal immune response, manifested as infiltration by a mixed population of plasma cells expressing IgG (IgG2, IgG4), IgA or IgM. In the feline tumours CD3+ small T lymphocytes were included in these infiltrates.

Localization of clonal T cells to the epidermis in cutaneous T-cell lymphoma

BACKGROUND

Mycosis fungoides (MF) is a form of cutaneous T-cell lymphoma (CTCL) characterized by progression of clonal, epidermotropic T cells with the proliferative (Ki-67+) T-cell fraction primarily confined to the epidermis in early CTCL.

OBJECTIVE

Our purpose was to determine whether the malignant clone (recognized by its clonal T-cell receptor [TCR] rearrangement) might also be localized to the epidermal compartment by differential Southern blot analysis.

METHODS

A rapid heat-saline technique was used to separately isolate epidermal and dermal DNA from 11 patients with CTCL (1 with disease in the pre-MF stage, 4 with patch-stage MF, 3 with plaque-stage MF, 1 with tumor-stage MF, 1 with Sézary syndrome, and 1 with non-MF peripheral T-cell lymphoma). Whole and heat-saline separated 6 mm biopsy specimens (obtained from the same lesion) were analyzed by standard Southern blotting with 5 to 10 micrograms of DNA digested with BamHI, HindIII, or EcoRI in each case. Filters were probed with a 32P-labeled TCR-C beta complementary DNA. Skin compartment localization of TCR-C beta rearrangement was compared with results of diagnostic immunophenotyping and expression of proliferating cell nuclear antigen.

RESULTS

DNA yields were as follows: from the whole specimens, 14.5 to 62.5 micrograms; from epidermal sheets, 2 to 42.5 micrograms; and from the dermis specimens, 2.5 to 25.5 micrograms. Whole and separated specimens from one patient with plaque-stage disease, three with patch-stage disease, and one patient with pre-MF disease revealed no rearrangement. Six patients had detectable gene rearrangements in the whole specimen by Southern blot; four of six had identical rearrangements in only the epidermal fragment (including the Sézary syndrome biopsy specimen) and not the dermis. The other two patients had only dermal TCR-C beta rearrangement. No relation was seen between immunophenotype or proliferating cell nuclear antigen expression and the localization of TCR-C beta rearrangements. However, the degree of epidermotropism significantly correlated with the presence of TCR-C beta rearrangements in the epidermal sheets.

CONCLUSION

This study demonstrates that the malignant clone in CTCL can be localized to the epidermal compartment in most cases in which a TCR rearrangement is detectable and that these clones are associated with epidermal proliferation of lymphocytes. This technique of differential epidermal versus dermal Southern analysis for TCR rearrangement may improve sensitivity by helping to distinguish reactive from malignant T-cell populations in future studies of the pathogenesis of CTCL.