Detection of intracellular IFN-γ and IL-4 cytokines in CD4+ and CD8+ T cells in the peripheral blood of dogs naturally infected with Leishmania infantum.

Canine leishmaniosis (CanL) is a systemic zoonotic disease the clinical manifestations of which can range from self-healing cutaneous lesions to disseminated visceral disease. Effective activation of cellular immunity is the cornerstone of resistance against Leishmania infantum in infected dogs. The aim of this cross-sectional, controlled study was the intracellular detection of interleukin 4 (IL-4) and interferon-γ (IFN-γ) in CD4+ and CD8+ lymphocytes in the peripheral blood of 40 dogs naturally infected with L. infantum by applying flow cytometry. The percentage of CD4+IL-4+ and CD8+IL-4+ lymphocytes (with or without immunostimulation) was low in the clinically healthy and subclinically infected dogs in contrast to clinically affected ones. In the same groups of dogs, the percentage of CD4+IFN-γ+ and CD8+IFN-γ+ T cells in their resting phase and following specific immunostimulation with Leishmania soluble antigen (LSA) was also low. CD4+IL-4+ and CD8+IL-4+ T cell percentage was higher in sick compared to clinically healthy and subclinically infected dogs, after immunostimulation. The corresponding figure of CD8+IL-4+ cells in sick dogs after LSA immunostimulation was also increased thus underlining the important role these cells may play in humoral immunity and perhaps the progression of CanL.

Cutaneous immune mechanisms in canine leishmaniosis due to Leishmania infantum.

Canine leishmaniosis (CanL) caused by the parasite Leishmania infantum is a systemic disease with variable clinical signs. The disease is endemic in the Mediterranean countries and dogs are the main domestic reservoir of the parasite. The quite complicated immune response against the parasite is crucial for the evolution of CanL infection with the skin playing a major role in its immunopathogenesis. After the inoculation of Leishmania promastigotes into the dermis by sand fly bites, complement factors, Langerhan's cells, neutrophils, fibroblasts and keratinocytes are involved in the activation of the innate arm of the skin immune system, with the macrophages and dendritic cells to play a major key role. The effective activation of cellular immunity is the cornerstone of dog's resistance against the parasite. Promastigotes reaching the dermis are engulfed, processed and transferred by APCs to draining lymph nodes to stimulate naïve T-cells for proliferation and differentiation into armed effector T-cells. Th1 cells activate the infected macrophages to kill Leishmania, whereas Th2 cells divert the immune response to humoral immunity and down regulation of cellular immunity with Th1 cell anergy. Inhibition of co-stimulatory molecules expression by infected macrophages contributes to T-cell anergy. In canine subclinical infections cutaneous lymphocytic infiltrate and parasites are absent, as opposed to dogs with clinical leishmaniosis. CD8+ cells constitute a significant population of cellular immunity in CanL since they outnumber CD4+ cells in the dermis, producing IFN-γ in sub clinically infected dogs and high levels of IL-4 in dogs with clinical leishmaniosis. Numerous B-lymphocytes have been shown to heavily infiltrate the dermis at least in exfoliative dermatitis in CanL. A mixed Th1/Th2 cytokine profile has been found in the dermis of naturally infected with L. infantum dogs. In the skin of dogs with clinical leishmaniosis, where plasma cells outnumber T lymphocytes in the dermal infiltrate, there is an overproduction of IL-4, IL-13 and TNF-α leading to Th2-biased humoral immune response. The issue of humoral immunity polarization in CanL remains controversial. Much still needs to be learned about other mechanisms underlying the complex interaction between the skin immune system and the parasite.

Molecular detection of Leishmania infantum in wild rodents (Rattus norvegicus) in Greece.

Leishmania infantum and Leishmania tropica are the species responsible for visceral leishmaniasis and cutaneous leishmaniasis respectively. In Greece, both diseases are endemic. The dog is considered the main reservoir of L. infantum, whereas the role of other animals for both L. infantun and L. tropica is unknown. Spleens from wild Rattus norvegicus, live trapped in Greece, were examined for the presence of Leishmania parasites by PCR. Out of 16 samples examined, only one was found positive for L. infantum with scant amount of parasitic DNA present. This is the first documented case of detection of L. infantum in R. norvegicus in Greece. The results of this preliminary study indicate that R. norvegicus is unlikely to be a reservoir for Leishmania parasites in Greece.

First isolation of Legionella species, including L. pneumophila serogroup 1, in Greek potting soils: possible importance for public health.

A total of 21 Legionella isolates were recovered from six out of 22 samples of potting soil from the Athens area, Greece. Legionella pneumophila (serogroups 1 and 2-15) and species and serotypes included in the group of L. longbeachae serogroups 1 and 2, L. bozemanii serogroups 1 and 2, L. dumoffii, L. gormanii, L. jordanis, L. micdadei and L. anisa were isolated on BCYEalpha agar containing cysteine, GVPC and natamycin and on BCYEalpha agar containing cysteine, Wadowsky Yee supplement and natamycin. The bacterial load was 4000-120 000 CFU/g of potting soil. The isolation of L. pneumophila serogroup 1 from Greek potting soils is reported here for the first time.

Determination of CD4+ and CD8+ T cells in the peripheral blood of dogs with leishmaniosis before and after prolonged allopurinol monotherapy.

Canine leishmaniosis (CL) is a common systemic parasitic disease that is endemic in many Mediterranean countries including Greece. The immune reaction to the parasite is critical to the outcome of the infection and the response to treatment. Some studies have shown a reduction of circulating CD4+ T cells and of the CD4+/CD8+ ratio in dogs with CL and these changes normalised following treatment with meglumine antimoniate or amphotericin B. Allopurinol is used as a monotherapy for the chronic treatment of CL. The aim of the present study was to determine the circulating CD4+ and CD8+ T lymphocyte numbers and the CD4+/CD8+ ratio in 19 dogs diagnosed with CL before and after prolonged allopurinol monotherapy (18 months). A significant decrease in circulating CD4+ T cells was observed in dogs with CL before treatment. Prolonged allopurinol monotherapy improved the number of circulating CD4+ T cells, but did not restore their number to within the normal range.

Epitheliotropic cutaneous lymphoma (mycosis fungoides) in a coati.

The aim of this report was to present a case of epitheliotropic cutaneous lymphoma (mycosis fungoides) in a coati. The animal was presented for evaluation of a non-pruritic nodule. Although the diagnosis of cutaneous histiocytoma was made histologically, plaques and erosions appeared in new areas of the skin along with rapid deterioration of body condition that led to euthanasia in less than one month following initial presentation. Epitheliotropic cutaneous lymphoma was confirmed with plaque biopsies. Cross-reactivity of a polyclonal antihuman CD3 antibody to coati T lymphocytes was also observed. Apart from skin lesions, only pleuritis was post-mortem diagnosed most likely because of immunosuppression secondarily to malignant neoplasia.

Providencia stuartii infection in a dog with severe skin ulceration and cellulitis.

The aim of this report is to present a case of severe skin ulceration and cellulitis in a seven year old mongrel dog following cystitis. The Providencia stuartii strain was the only isolate from skin lesions. This bacterium is a Gram-negative rod belonging to the family of Enterobacteriaceae. To the best of our knowledge, even though there are some reports in the literature concerning animal infections with Providencia species, there have been no cases of cellulitis in which this pathogen is involved. The Providencia stuartii strain was highly sensitive to amikacin, and the dog responded quickly to this antibiotic.

Cellular immunophenotyping of exfoliative dermatitis in canine leishmaniosis (Leishmania infantum).

Lymphocyte subsets, major histocompatibility complex (MHC)-II expressing cells and number of amastigotes in the epidermis and dermis were investigated immunohistochemically in 48 dogs with patent leishmaniosis, with or without exfoliative dermatitis (ED) to study the immunopathogenesis of this common cutaneous form of the disease. Skin biopsies were obtained and compared for ED sites (group A, n = 26), normal-appearing skin from the same animals (group B, n = 24), and leishmanial dogs not exhibiting ED (group C, n = 22), and normal controls (group D, n = 22). The CD3+, CD45RA+, CD4+, CD8+ (CD8a+), CD21+, and MHC-II+ cells and leishmania amastigotes were identified immunohistochemically and counted with the aid of an image analysis system. Pyogranulomatous to granulomatous dermatitis, expressed in various histopathological patterns, was noticed in all groups A and B and in half of group C dogs. In the epidermis, the low number of T-cells and their subsets did not differ significantly between groups A and B, but CD8+ outnumbered CD4+ lymphocytes in both groups. MHC-II+ expression on epidermal keratinocytes was intense in the skin with and without lesions from dogs with ED but not in group C dogs. CD3+, CD8+ and MHC-II+ cells were fewer in group C compared to group A and B dogs. In the dermis, CD3+ cells in group A animals were mainly represented by the CD8+. CD45RA+ and CD21+ cells were also seen in high numbers. MHC-II expression, potentially in lymphocytes, fibroblasts, dendritic cells, and macrophages was intense. The numbers of all cellular subpopulations in the dermis were significantly different between the groups, being highest in group A and lowest in group D. In sebaceous adenitis sites, CD4+ outnumbered CD8+ cells in contrast to the neighbouring dermis and the epidermis. The number of CD21+ and CD45RA+ cells was much lower in the inflamed sebaceous glands compared to the dermis. Finally, the number of amastigotes in the normal-appearing skin was significantly higher in the ED dogs (group B) than in those not exhibiting this cutaneous form of the disease (group C).

Adult-onset demodicosis in two dogs due to Demodex canis and a short-tailed demodectic mite.

Infestation with a short-tailed demodectic mite and Demodex canis was diagnosed in both a six-and-a-half-year-old and a four-year-old dog. The clinical picture was compatible with generalised demodicosis complicated by staphylococcal pyoderma (case 1), or localised demodicosis (case 2). In both cases, the short-tailed demodectic mite outnumbered D canis in superficial skin scrapings. The laboratory findings (lymphopenia, eosinopenia, increased serum alkaline phosphatase and alanine aminotransferase activities, diluted urine and proteinuria) and the results of a low dose dexamethasone suppression test were suggestive of underlying hyperadrenocorticism in the first case. Hypothyroidism was considered a possibility in the second case, owing to the sustained bradycardia and the extremely low basal total thyroxine value. Systemic treatment with ivermectin and cephalexin (case 1), or topical application of an amitraz solution in mineral oil, along with sodium levothyroxine replacement therapy (case 2), resulted in a complete resolution of the skin lesions and the disappearance of both types of demodectic mite after two and one and a half months, respectively.