A randomized placebo-controlled double-blinded study comparing oral and subcutaneous administration of mistletoe extract for the treatment of equine sarcoid disease.

BACKGROUND: Equine sarcoids (ES) are the most common cutaneous tumors in equids. Systemic treatment options are sparse. Subcutaneous (SC) injections of Viscum album extract (VAE) demonstrate efficacy as a systemic treatment directed against ES. OBJECTIVES/AIM: To critically assess the therapeutic efficacy of orally administered VAE. ANIMALS: Forty-five ES-affected, privately owned, 3-12 year-old horses. METHODS: A 3-armed randomized placebo-controlled, double-blinded study was conducted in a double-dummy design. Horses were subjected to oral administration and SC injections of either VAE or placebo (VAE oral/placebo SC, VAE SC/placebo oral, placebo oral/placebo SC) over a 7-month treatment period. Primary endpoint was the change of baseline of a composite index of ES number and ES area after 14 months. Second endpoint was the clinical response. RESULTS: No statistically significant difference in the composite endpoint between the 3 study arms was found. The primary endpoint showed 4 (27%) horses in the VAE oral group with complete ES regression, 3 (21%) in the VAE SC injection group, and 2 (13%) in the placebo group. The clinical response revealed complete or partial regression in 6 horses of the oral VAE group (40%), 4 of the SC injection group (29%), and 4 of the placebo group (25%). Direct comparison of oral VAE and placebo showed an odds ratio, stratified for prognosis of 2.16 (95%-CI: 0.45-10.42) and a P-value of 0.336. CONCLUSION AND CLINICAL IMPORTANCE: Oral administration of VAE is well tolerated. No statistically significant difference in the effectiveness of systemic VAE versus placebo against ES was found.

Performance of fine-needle aspirate testing compared with superficial swab testing for quantification of BPV-1/-2 viral load in equine sarcoids.

Bovine papillomavirus (BPV) types 1 and 2 are causally associated with equine sarcoid, the most common mesenchymal neoplasm of horses, but the viral load (VL) differs between lesions. Sensitive and accurate BPV detection and quantification is essential for clinicians to confirm clinical suspicion, as well as in research settings for stratifying these skin lesions. Due to the limitations of histopathology in sarcoid diagnosis, PCR screening of superficial swabs constitutes the principal sampling method for BPV detection. This study aimed to investigate the ability of superficial swabs and fine-needle aspirates (FNA) to accurately detect the VL in equine sarcoids, considering the main clinical types: occult, nodular, verrucous and fibroblastic. Superficial swabs and FNAs from a series of sarcoid-affected horses were tested in parallel for BPV DNA quantification. Quantitative real-time PCR screening of postoperative tissue biopsies served as reference standard for the accuracy assessment of the viral titters. Our results indicate that VL is not a predictor of the clinical type. Student's t-test results gave evidence of a significant difference between both sample methods (P < 0.001) with FNA giving the best approximation of the actual VL (P < 0.01). In contrast to superficial swabs, the reference standard correlated moderately with FNA in general (P < 0.05; r = 0.39) and strongly with FNA results within the occult sarcoid group (P < 0.05; r = 0.59). In conclusion, the correlation of FNA with the reference standard was strong enough to suggest this is the preferred method for quantifying VL in sarcoids.

Immunogenicity analysis of BPV-1 positive equine sarcoid-derived cultured fibroblasts.

Sarcoids are the most common equine skin tumours Although they do not metastasize, they can be locally aggressive and cause significant clinical symptoms in affected horses. Despite being common, very little is known about the host immune response and the biological mechanisms underlying persistence and recurrence of equine sarcoids. The latter reflects the need for further research in this field. This in-vitro study used sarcoid explants from horses with naturally occurring sarcoids (n = 12) to evaluate the induction of a humoral immune response directed against equine sarcoid-derived bovine papilloma-virus (BPV)- 1 infected fibroblasts using a flow cytometric crossmatch assay. The presence of antibodies against exogenous bovine serum albumin (BSA) and fibroblast-like mesenchymal stromal cells (MSCs) was also evaluated by ELISA and flow cytometry, respectively. The viral load in the sarcoid explants, the corresponding cultured sarcoid fibroblasts, and matched peripheral blood mononuclear cells (PBMCs) from affected horses were determined by quantitative BPV-1/- 2 PCR analysis. Antibodies against autologous sarcoid cells were present in six out of twelve sarcoid-affected horses. Serum from all horses showed cross reactivity with allogeneic sarcoid cells, while only a part reacted with BSA or MSCs. Screening of host PBMCs demonstrated the absence of BPV E1 nucleic acids. Statistical analysis revealed a significantly higher mean viral load in the parental sarcoid tissue compared to the low passage fibroblasts (P < 0.001). These results support the hypothesis that sarcoid-affected horses may develop antibodies recognizing tumour-specific antigens. In contrast to sarcoid explants, equine PBMCs do not seem to contain complete BPV genomes. These results provide a basis for future investigations on the clinical relevance of these antibodies.

Management of equine sarcoids.

Sarcoids are the most common cutaneous neoplasm of the horse, arising as a result of a neoplastic proliferation of fibroblasts associated with infection with bovine papillomavirus, most notably types 1 and 2. Although they do not metastasise, they are locally invasive and aggressive, and can lead to important welfare concerns, interfere with tack and therefore impede athleticism, and undoubtedly lead to a reduction in the value of affected horses. This review discusses the evidence behind the most commonly used treatments for equine sarcoids. The most commonly used treatments are discussed. No one treatment is universally successful, and there are many treatments with varying level of scientific evaluation and reported success rates.

ALVAC-fIL2, a feline interleukin-2 immunomodulator, as a treatment for sarcoids in horses: A pilot study.

BACKGROUND: Sarcoid tumors are common in horses and may negatively impact the performance and value of the horse. No known treatment is reliably successful. HYPOTHESES/OBJECTIVES: To determine tolerability, overall response rate, time to response, and progression-free survival of horses with biopsy-confirmed or suspected sarcoids treated with ALVAC-fIL2. ANIMALS: Client-owned horses with measurable, presumed- or biopsy-confirmed sarcoid tumors. METHODS: Prospective pilot study. One milliliter of ALVAC-fIL2 was injected into 4 to 5 areas of the sarcoid(s) in each horse (week 0); this treatment was repeated in weeks 1, 3, and 7. Sarcoids were measured at each visit, and response to treatment was determined according to the Response Evaluation Criteria in Solid Tumors for dogs (v1.0). After the final treatment, horses were reassessed and sarcoids remeasured every 3 months until tumor progression or for a minimum of 1 year if progression was not documented. RESULTS: Fourteen horses were included. Tumor size decreased in 86% of the horses, and the median time to first response was 89 days (range, 34-406 days). Median time to best response was 211 days (range, 56-406 days), but 3 of the sarcoids still were decreasing in size at the time of final evaluation. The median progression-free interval was not reached. Adverse events were minimal and included transient focal inflammation in 2 horses. CONCLUSIONS AND CLINICAL IMPORTANCE: Intratumoral injection of ALVAC-fIL2 has promise as a well-tolerated and effective, tissue-sparing treatment for horses with sarcoid tumors.

Treatment of equine sarcoids using recombinant poxviruses expressing feline interleukin-2.

BACKGROUND: Interleukin (IL)-2 stimulates antitumour immunity and is successfully used for the treatment of different neoplasias. HYPOTHESIS/OBJECTIVES: Canarypox virus locally expressing feline IL-2 is safe and can be used to treat equine sarcoids. ANIMALS: Twenty horses of different breeds with a median age of eight years (interquartile range 6.0-13.3 years) and a total number of 59 sarcoids were included in the study. METHODS: In this prospective clinical trial, sarcoids were injected twice seven days apart, with a recombinant canarypox virus expressing feline IL-2. Complete blood counts (CBC) and fibrinogen levels were measured before treatment and on days 1, 2, 7 and 8. RESULTS: Complete regression was achieved in eight horses (40%) and partial regression in two horses (10%). No change in sarcoid size was observed in two horses (10%) and the disease progressed in five horses (25%). Sarcoids of three horses (15%) showed initial response followed by tumour growth. There were no significant changes in CBC and fibrinogen levels after either injection. One horse developed a mild fever the day after each injection, which subsided without treatment the following day. CONCLUSIONS: Treatment of equine sarcoids with recombinant canarypox virus expressing feline IL-2 seems to be a safe therapy option. Although the expression of IL-2 after vector injection and its biological activity in horses were not proven in this study, the treatment resulted in regression and partial regression in 50% of the cases. Further studies are necessary to verify these findings and to establish a treatment protocol.

Evaluation of Locally Injected Mycobacterium Cell Wall Fraction in Horses with Sarcoids.

A reformulation of Mycobacterium cell wall fraction immunotherapeutic can be used to successfully treat sarcoids in horses. Sarcoids are reported to be the most common equine skin tumors with tumor type and location influencing the choice of treatment. Wide surgical excision is curative for many tumors, but may not always be feasible. Previous studies have reported sarcoid regression after injection with mycobacterial cell wall immunotherapeutics. A new formulation of the Mycobacterium phlei cell wall fraction immunostimulant (Immunocidin Equine) was used to treat cutaneous tumors in horses. Equids with skin tumors diagnosed as sarcoids were enrolled in the study. Sarcoids were injected at the initial visit with Immunocidin Equine and subsequently at approximately 2-week intervals. Of 17 cases, nine cases were completely resolved at the end of the study period evaluation or at the time of final follow-up (52.9%). Three cases were reported as improved (smaller), but not resolved (17.6%). Three cases were discontinued from the study as the respective masses were growing larger or not resolving (17.6%). One case (5.8%) with two masses had resolution of one mass, whereas the other tumor had a small regrowth 5 months after the last treatment. One case (5.8%) was lost to follow-up. All cases had mild to moderate swelling of the injection site, and some cases had discharge after the second, third, or fourth injections. No serious systemic side effects or complications were encountered during the study.

Biological behaviour and clinical outcome in 42 cats with sarcoids (cutaneous fibropapillomas).

Feline sarcoids (or cutaneous fibropapillomas) are rare dermal neoplasms. There are currently no reported statistics concerning their clinical behaviour. Our objective with this retrospective, multi-institutional study was to describe the clinical presentation and biological behaviour of sarcoids in cats and to determine the oncologic outcome following surgical resection. Medical records from a laboratory database and six contributing institutions were searched to identify cats with histologically confirmed sarcoids. Forty-two cats were included in the study. The majority of sarcoids occurred on the face, particularly rostral locations such as the lips and nasal planum. Complete and incomplete histologic excision was achieved in 18 and 21 cats, respectively. The overall local recurrence rate was 40.5%. Complete histologic excision was associated with a significantly lower local recurrence rate (11.1%) and longer disease-free interval (not reached) compared with cats with incompletely excised sarcoids (66.7% and 250 days, respectively). The 1- and 2-year local recurrence rates were 0% and 7%, respectively, for cats with complete histologic excision, and 67% at both time intervals for cats with incomplete histologic excision. Five of the cats (83.3%) treated with curative-intent surgical revision following local tumour recurrence had no further local recurrence. All cats that died secondary to tumour-related causes had initial incomplete histologic excision and were euthanized because of local recurrence. Wide surgical resection of feline sarcoids is recommended to achieve complete histologic excision, local tumour control and a potential cure. For cats with incomplete histologic excision or local tumour recurrence, repeat surgical resection is recommended.

Clinical and histopathological presentation and successful treatment with ciclosporin for canine sarcoidosis: a case report.

BACKGROUND: Sarcoidosis is a granulomatous disease histologically characterized by naked granulomas in various mammals. Canine sarcoidosis is a rare disease which can cause nonpruritic papule, plaques and nodules on the trunk, neck, face and ear; it is usually treated with corticosteroids. To date, there are no published reports on alternatives to corticosteroids treatment. OBJECTIVES: To report a case of canine cutaneous sarcoidosis successfully treated with oral ciclosporin. ANIMAL: An 11-year-old beagle dog was presented with multiple pleomorphic plaques on the lateral thighs and dorsal trunk. METHODS AND MATERIALS: Skin punch biopsy specimen were collected and analysed via routine histological examination and immunohistochemistry. After 14 weeks of oral ciclosporin treatment, repeat skin biopsy specimens were collected. RESULTS: Histopathological examination revealed noncaseating epithelioid cell granuloma formation in the dermis. Dermal epithelioid cells were positive for CD18 and Iba1, but not for CD3, CD20 and E-cadherin based on immunohistochemistry findings. Acid-fast bacteria, fungi and Leishmania spp. were not detected by special stains, culture or polymerase chain reaction. An initial two week treatment with immunosuppressive doses of oral prednisolone and doxycycline was not effective. Skin lesions were almost in remission after 14 weeks of oral ciclosporin treatment without adverse events. Histologically, the dermal granulomatous lesions regressed and were replaced by fibrous tissues after ciclosporin treatment. CONCLUSIONS AND CLINICAL RELEVANCE: This case report describes the clinical and histopathological presentation including immunohistochemistry and treatment outcome of a case of canine sarcoidosis Ciclosporin may be an effective alternative to corticosteroids for treating canine sarcoidosis.

The Equine Sarcoid: Why Are There so Many Treatment Options?

This article discusses the main treatments for sarcoid and the specific difficulties of these. It explains to some extent why the frustrations of a condition for which there is no single treatment option have led to the burgeoning of an industry of irrational treatments. The factors that need to be considered before selecting an option for treatment are wider than is the case in most other disease entities as a result of the complexity of the condition, its variable phenotypes, and the individual perceptions and experiences of both veterinarians and owners.

Genetic evaluation of bovine papillomavirus types detected in equine sarcoids in Poland.

BACKGROUND: Equine sarcoids are the most common neoplasms in horses. Bovine papilloma- virus type 1 (BPV-1) is the main viral type identified in equine sarcoids in Europe. OBJECTIVE: The aim of the present study was to genetically evaluate BPV types based on DNA analyses of the CDS of the L1 gene. The presence of BPV DNA was confirmed by Degenerate Oligonucleotide-Primed Polymerase Chain Reaction (DOP PCR) with FAP59/FAP64 consensus primers. RESULTS: The DNA was detected in 21/40 (52.5%) of clinically diagnosed sarcoids. More than half of 14 isolates (66.7%) shared 100% homology with BPV-1 Deltapapillomavirus 4 isolate 09 asi UK (Acc. No. MF384289) and 99% nucleotide identity with BPV-1 isolate EqSarc1 (Acc. No. JX678969). A comparison with BPV-1 isolate EqSarc1 revealed one silent mutation in C5827T which did not change the aminoacid codon. The remaining 6 isolates (28.6%) shared 100% nucleotide identity with the BPV-1 (Acc. No. X02346) "wild type" isolate, and 1 isolate (4.8%) demonstrated 99% nucleotide identity with BPV-2 (Acc. No. M20219). CONCLUSIONS: Variants of BPV-1 isolate EqSarc1 (Acc. No. JX678969) constitute the most prevalent type of BPV-1 in Polish horses.

Differentially expressed microRNAs, including a large microRNA cluster on chromosome 24, are associated with equine sarcoid and squamous cell carcinoma.

The aim of this study was to investigate microRNA (miRNA) differential expression in the two most common equine skin tumours, equine sarcoid (ES) and squamous cell carcinoma (SCC), and its potential influence on the tumour microenvironment at post-transcriptional level. We investigated miRNA fingerprints in four subgroups: mild (ESM) and aggressive (ESA) ES and ocular SCC (oSCC) and genital SCC (gSCC). Three tumours and three control samples were included in each of the four subgroups. Following next generation sequencing, miRNA differential expression analysis using DESeq2 was carried out. Pathways associated with the human mature homologues of identified dysregulated miRNAs were predicted using DIANA- miRPath v3.0. When comparing tumour vs control tissue, 57 miRNAs in ESM, six in ESA, 47 in oSCC and zero in gSCC were found to be differentially expressed and may thus serve as potential diagnostic tissue biomarkers. Whereas, ES lesions in general were associated with downregulation of the miR-200 family, which may trigger epithelial-mesenchymal transition, ESM lesions were associated with upregulation of the proposed tumour-suppressive miRNA cluster on equine chromosome 24. In contrast, the oSCC tumours showed downregulation of this cluster as well as downregulation of the miR-34 family, which may favour oSCC tumour cell metabolism. To further validate the proposed diagnostic miRNA fingerprints and their suggested biological effects, further miRNA studies need to be carried out in larger study cohorts.

The clinical diagnosis of equine sarcoids-Part 2: Assessment of case features typical of equine sarcoids and validation of a diagnostic protocol to guide equine clinicians in the diagnosis of equine sarcoids.

Research has shown that the accuracy of the clinical diagnosis of equine sarcoids (ES) can be improved. Particularly, less experienced veterinarians are often mistaken in their clinical judgement despite a high level of diagnostic confidence. The aim of this study was to develop and assess the performance of a diagnostic protocol (DP) to improve diagnostic accuracy and identify diagnostically challenging cases. The design of the DP was based on typical clinical features of ES and its algorithm was optimised through repeated tests on clinical cases prior to validating its performance in a representative online examination. A total of 22 equine practitioners and 31 veterinary students used the DP to diagnose 40 standardised ES and non-ES cases in an online examination. Scores of these 53 respondents were compared to scores of 128 respondents of comparable levels of expertise, and 14 experts, all assessing the same cases without using the DP. Overall, respondents using the DP were significantly more likely (odds ratio (OR) 1.25; 95% confidence interval (95% CI) 1.09-1.43) to diagnose a case correctly compared to respondents not using the DP and felt significantly more confident of their diagnosis (OR 1.53; 95% CI 1.39-1.67). Thus, the DP proved to be a reliable tool to increase clinical diagnostic accuracy and diagnostic confidence. The DP algorithms may be further improved with experiences gained from its application in equine practice and clinicians will be able to optimise their diagnostic accuracy and selection of lesions requiring a biopsy.

The clinical diagnosis of equine sarcoids - Part 1: Assessment of sensitivity and specificity using a multicentre case-based online examination.

Equine clinicians and researchers often make the diagnosis of equine sarcoids (ES) on clinical assessment alone, without histopathological confirmation. However, the accuracy of the clinical diagnosis of ES has not been critically assessed. To assess sensitivity, specificity, positive and negative predictive values of the clinical diagnosis of ES, 40 clinical cases with histologically confirmed equine skin lesions (26 ES and 14 non-ES) were compiled in a representative online examination. For each case and lesion, at least one photograph and all relevant information were presented in a standardised format. This included the horse's signalment, lesion localisation, lesion progression, presence of other skin lesions, earlier treatments and response to treatment. No information relevant for the assessment of the lesion was intentionally withheld. Fourteen ES experts, 39 board-certified equine specialists, 103 equine practitioners and 25 novices categorised the cases into ES or non-ES and graded their level of diagnostic confidence on a scale from 1 to 6 for each case. The overall success rate was 82.0% while sensitivity and specificity were 83.3% and 79.6%, respectively. The positive and negative predictive values were 88.4% and 72.0%, respectively, in the tested population with a 66% prevalence of ES. However, less experienced veterinarians were frequently wrong in their clinical judgement despite a high level of diagnostic confidence. Therefore, the authors propose to develop a diagnostic tool to help clinicians optimise their selection of lesions requiring a biopsy. Ultimately, this will help reduce costs and morbidity generated by unnecessary diagnostic and therapeutic efforts.

The possible role of Stomoxys calcitrans in equine sarcoid transmission.

The association between bovine papillomavirus (BPV) and equine sarcoids is well established, but it is unclear how the virus spreads. Although evidence in support of viral spread through direct animal contact exists, this does not explain sarcoid development in isolated equids. BPV DNA has been detected in flies, which could indicate that these insects serve as a vector. This study aimed to investigate whether BPV-negative stable flies (Stomoxys calcitrans) become positive for BPV DNA after exposure to equine sarcoid or bovine papilloma tissue under experimental conditions and, if so, for how long. A total of 420 stable flies were caught alive and exposed to BPV positive equine sarcoid or bovine papilloma tissue. During the following week, dead flies were collected daily and BPV loads were determined by quantitative PCR. There was a significant rise in BPV load after tissue exposure both in sarcoid and papilloma exposed flies, but the viral load was higher and remained high for a longer time after exposure to papilloma tissue compared to sarcoid tissue. Within days, viral loads decreased again and became indifferent from loads before exposure. The results of these experiments indicate that BPV transmission by S. calcitrans seems possible and is more likely to occur after contact with bovine papillomas than with equine sarcoids. Transmission seems only possible shortly after tissue exposure. Further research could include experimental induction of sarcoids with BPV positive stable flies, or a repeat of the experiment with micro-dissection prior to PCR.

Potential of a BPV1 L1 VLP vaccine to prevent BPV1- or BPV2-induced pseudo-sarcoid formation and safety and immunogenicity of EcPV2 L1 VLPs in horse.

We have previously shown that immunization of horses with bovine papillomavirus type 1 (BPV1) L1 virus-like particles (VLPs) is safe and highly immunogenic and that BPV1 and bovine papillomavirus type 2 (BPV2) are closely related serotypes. Here we evaluated the protective potential of a BPV1 L1 VLP vaccine against experimental BPV1 and BPV2 challenge and studied the safety and immunogenicity of a bivalent equine papillomavirus type 2 (EcPV2)/BPV1 L1 VLP vaccine. Fourteen healthy horses were immunized with BPV1 L1 VLPs (100 µg per injection) plus adjuvant on days 0 and 28, while seven remained unvaccinated. On day 42, all 21 horses were challenged intradermally at 10 sites of the neck with 107 BPV1 virions per injection. In analogy, 14 horses immunized twice with EcPV2 plus BPV1 L1 VLPs (50 µg each) and seven control animals were challenged with 107 BPV2 virions per injection. Immunization with BPV1 L1 VLPs alone induced a robust antibody response (day 42 median titre: 12 800), and BPV1-inoculated skin remained unchanged in 13/14 vaccinated horses. Immunization with the bivalent vaccine was safe, resulted in lower median day 42 antibody titres of 400 for BPV1 and 1600 for EcPV2 and conferred significant yet incomplete cross-protection from BPV2-induced tumour formation, with 11/14 horses developing small, short-lived papules. Control horses developed pseudo-sarcoids at all inoculation sites. The monovalent BPV1 L1 VLP vaccine proved highly effective in protecting horses from BPV1-induced pseudo-sarcoid formation. Incomplete protection from BPV2-induced tumour development conferred by the bivalent vaccine is due to the poorer immune response by immune interference or lower cross-neutralization titres to heterologous BPV2 virions.

Treatment of sarcoids in equids: 230 cases (2008-2013).

OBJECTIVE To evaluate outcomes following treatment of sarcoids in equids and to identify risk factors for treatment failure in these patients. DESIGN Retrospective case series. ANIMALS 230 equids with 614 sarcoids. PROCEDURES Records were searched to identify equids treated for ≥ 1 sarcoid between 2008 and 2013. A standardized protocol was used to determine treatment choice (electrosurgery, electrosurgery with intralesional placement of cisplatin-containing beads, topical administration of imiquimod or acyclovir, cryosurgery, bacillus Calmette-Guerin vaccine injection, or intralesional injection of platinum-containing drugs). Data regarding animal, tumor, treatment, and outcome variables were collected. Complete tumor regression without recurrence for ≥ 6 months was considered a successful outcome. Success rates were calculated; binary logistic regression analysis was used to identify risk factors for treatment failure and to compare effects of the 2 topical treatments. A χ(2) test was used to compare effects of the number of Bacillus Calmette-Guerin vaccine or cisplatin-containing drug injections on outcome. RESULTS The overall success rate was 460 of 614 (74.9%). Electrosurgical excision resulted in the highest treatment success rate (277/319 [86.8%]); odds of treatment failure were significantly greater for intralesional injection of platinum-containing drugs, cryosurgery, and topical acyclovir treatment. Odds of treatment failure were also significantly greater for sarcoids on equids with multiple tumors than for solitary lesions, and significantly lower for sarcoids on equids that received concurrent immunostimulating treatment for another sarcoid than for those on patients that did not receive such treatment. CONCLUSIONS AND CLINICAL RELEVANCE Selection bias for treatments was inherent to the study design; however, results may assist clinicians in selecting treatments and in determining prognosis for equids with sarcoids treated according to the described methods.

Equine sarcoid: In situ demonstration of matrix metalloproteinase expression.

Sarcoids are the most prevalent equine skin tumours and remain a therapeutic challenge due to their differing clinical morphology, local aggressive behaviour, and high recurrence following surgical treatment. In vitro, sarcoid derived fibroblasts are invasive and express matrix metalloproteinase (MMP) -1, -2 and -9. It was hypothesised that the MMPs produced by neoplastic cells play a role in both their local invasiveness and interaction with the overlying epidermis (picket fence formation). The objective of this morphological study was to investigate the local behaviour and in situ MMP expression pattern in sarcoids of different clinical types. A total of 43 surgically excised sarcoids were examined by histology, immunohistology for the expression of MMP-1, -2 and -9, and transmission electron microscopy. Regardless of the clinical type, sarcoids showed local invasion of the dermis and damage to the basement membrane in areas of interaction with the epidermis. This was associated with MMP-1 expression in both neoplastic cells and epidermis. The results suggest a link between MMP-1 expression and the local aggressiveness of sarcoids regardless of the clinical type.

Increased FOXP3 expression in tumour-associated tissues of horses affected with equine sarcoid disease.

Recent studies suggest that regulatory T cells (Tregs) are associated with disease severity and progression in papilloma virus induced neoplasia. Bovine papilloma virus (BPV) is recognised as the most important aetiological factor in equine sarcoid (ES) disease. The aim of this study was to compare expression levels of Treg markers and associated cytokines in tissue samples of ES-affected equids with skin samples of healthy control horses. Eleven ES-affected, and 12 healthy horses were included in the study. Expression levels of forkhead box protein 3 (FOXP3), interleukin 10 (IL10), interleukin 4 (IL4) and interferon gamma (IFNG) mRNA in lesional and tumour-distant samples from ES-affected horses, as well as in dermal samples of healthy control horses were measured using quantitative reverse transcription polymerase chain reaction (PCR). Expression levels were compared between lesional and tumour-distant as well as between tumour-distant and control samples. Furthermore, BPV-1 E5 DNA in samples of ES-affected horses was quantified using quantitative PCR, and possible associations of viral load, disease severity and gene expression levels were evaluated. Expression levels of FOXP3, IL10 and IFNG mRNA and BPV-1 E5 copy numbers were significantly increased in lesional compared to tumour-distant samples. There was no difference in FOXP3 and cytokine expression in tumour-distant samples from ES- compared with control horses. In tumour-distant samples viral load was positively correlated with IL10 expression and severity score. The increased expression of Treg markers in tumour-associated tissues of ES-affected equids indicates a local, Treg-induced immune suppression.