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Proteolysis-targeting chimeras (PROTACs) are a promising new class of drugs that selectively degrade cellular proteins of interest. PROTACs that target oncogene products are avidly being explored for cancer therapies, and several are currently in clinical trials. Drug resistance is a substantial challenge in clinical oncology, and resistance to PROTACs has been reported in several cancer cell models. Here, using proteomic analysis, we found intrinsic and acquired resistance mechanisms to PROTACs in cancer cell lines mediated by greater abundance or production of the drug efflux pump MDR1. PROTAC-resistant cells were resensitized to PROTACs by genetic ablation of ABCB1 (which encodes MDR1) or by coadministration of MDR1 inhibitors. In MDR1-overexpressing colorectal cancer cells, degraders targeting either the kinases MEK1/2 or the oncogenic mutant GTPase KRAS G12C synergized with the dual epidermal growth factor receptor (EGFR/ErbB)/MDR1 inhibitor lapatinib. Moreover, compared with single-agent therapies, combining MEK1/2 degraders with lapatinib improved growth inhibition of MDR1-overexpressing KRAS-mutant colorectal cancer xenografts in mice. Together, our findings suggest that concurrent blockade of MDR1 will likely be required with PROTACs to achieve durable protein degradation and therapeutic response in cancer.

PROTACs (Proteolysis-Targeting Chimeras) represent a promising new class of drugs that selectively degrade proteins of interest from cells. PROTACs targeting oncogenes are avidly being explored for cancer therapies, with several currently in clinical trials. Drug resistance represents a significant challenge in cancer therapies, and the mechanism by which cancer cells acquire resistance to PROTACs remains poorly understood. Using proteomics, we discovered acquired and intrinsic resistance to PROTACs in cancer cells can be mediated by upregulation of the drug efflux pump MDR1. PROTAC-resistant cells could be re-sensitized to PROTACs through co-administering MDR1 inhibitors. Notably, co-treatment of MDR1-overexpressing colorectal cancer cells with MEK1/2 or KRASG12C degraders and the dual ErbB receptor/MDR1 inhibitor lapatinib exhibited potent drug synergy due to simultaneous blockade of MDR1 and ErbB receptor activity. Together, our findings suggest that concurrent blockade of MDR1 will likely be required in combination with PROTACs to achieve durable protein degradation and therapeutic response in cancer.

Background Canine leishmaniosis caused by Leishmania infantum is a neglected zoonosis transmitted by sand flies like Phlebotomus perniciosus. Clinical signs and disease susceptibility vary according to various factors, including host immune response and breed. In particular, Ibizan hounds appear more resistant. This immunocompetence could be attributed to a more frequent exposure to uninfected sand flies, eliciting a stronger anti-sand fly saliva antibody response. Methods This study aimed to investigate the prevalence of anti-P. perniciosus saliva antibodies in Ibizan hounds and dogs of other breeds in the Leishmania-endemic area of Mallorca, Spain, and to correlate these antibody levels with clinical, immunological and parasitological parameters. Anti-sand fly saliva IgG was examined in 47 Ibizan hounds and 45 dogs of other breeds using three methods: P. perniciosus whole salivary gland homogenate (SGH) ELISA; recombinant protein rSP03B ELISA; and rSP03B rapid tests (RT). Additionally, diagnostic performance was evaluated between methods. Results Results indicate significantly higher anti-SGH antibodies (P = 0.0061) and a trend for more positive SGH ELISA and RT results in Ibizan hounds compared to other breeds. General linear model analysis also found breed to be a significant factor in SGH ELISA units and a marginally significant factor in RT result. Although infection rates were similar between groups, Ibizan hounds included significantly more IFN-γ producers (P = 0.0122) and papular dermatitis cases (P < 0.0001). Older age and L. infantum seropositivity were also considered significant factors in sand fly saliva antibody levels according to at least one test. Fair agreement was found between all three tests, with the highest value between SGH and rSP03B RT. Conclusions To our knowledge, this is the first study elaborating the relationship between anti-P. perniciosus saliva antibodies and extensive clinical data in dogs in an endemic area. Our results suggest that Ibizan hounds experience a higher frequency of exposure to sand flies and have a stronger cellular immune response to L. infantum infection than other breed dogs. Additional sampling is needed to confirm results, but anti-P. perniciosus saliva antibodies appear to negatively correlate with susceptibility to L. infantum infection and could possibly contribute to the resistance observed in Ibizan hounds.

The leishmanin skin test (LST) is an in vivo technique commonly used to evaluate the Leishmania-specific cellular immune response in dogs. However, information regarding the local immune response in LST-positive reactions is scarce. We examined the pattern of toll-like receptor 2 (TLR2), TLR4, TLR7, interleukin- (IL-) 10, interferon gamma (IFN-γ), and (program death ligand) PD-L1 gene expression in LST-positive reactions and paired normal-looking skin of nine infected Ibizan hound dogs. Healthy skin from ten seronegative dogs from a nonendemic area was analysed as a negative control. Immune gene expressions were examined by quantitative PCR (qPCR) analysis. LST-positive reactions presented significant upregulation of TLR2, TLR4, IL-10, IFN-γ, and PD-L1 and downregulation of TLR7 when compared with healthy skin of seronegative control dogs from a nonendemic area. All transcripts but TLR7 were significantly higher in LST-positive reaction than in paired normal-looking skin of Ibizan hound. The expression profile of immune genes in LST-positive reactions was similar to that previously observed in clinically lesioned skin of mildly diseased dogs with papular dermatitis due to Leishmania infantum infection. This data provide additional support for the important role of TLRs in canine leishmaniosis.

Detection of Leishmania in cutaneous lesions is possible by visualization of amastigotes. Detection of Leishmania DNA by PCR presents greater sensitivity, and PCR has been used to diagnose cutaneous leishmaniosis in humans using noninvasive clinical specimens.Study I: to determine if Leishmania DNA could be efficiently extracted and amplified from archived Diff-QuikSamples from cutaneous lesions of 54 dogs.Study I: Leishmania-qPCR was performed on 19 glass slides (from nine dogs) with cytologically visible amastigotes. Fifteen slides with no visible amastigotes, obtained from 12 dogs seronegative for Leishmania by ELISA, served as controls. Study II: Leishmania-qPCR was performed on glass slides and FPI from cutaneous lesions compatible with clinical leishmaniosis in 33 dogs.Study I: all slides with visible amastigotes had positive qPCR, whereas all control slides yielded negative results. Study II: of 13 dogs definitively diagnosed with clinical leishmaniosis, eight had visible amastigotes on cytology, whereas Leishmania-qPCR was positive on 11 glass slides and 13 FPI. Leishmaniosis was ruled out by standard methods in 20 dogs, four of which yielded positive qPCR on FPI and/or glass slides.Leishmania-DNA can be detected efficiently by qPCR from cutaneous cytological specimens and FPI to diagnose Leishmania infection in dogs with cutaneous lesions suggestive of CanL.Détection de Leishmania dans les lésions cutanées est possible par visualisation des amastigotes. La détection de l’ADN de Leishmania par PCR présente une meilleure sensibilité et la PCR a été utilisée pour diagnostiquer la leishmaniose cutanée de l'homme à l'aide de techniques cliniques non invasives.Etude I : déterminer si l’ADN de Leishmania peut être efficacement extraite et amplifiée de lames colorées au Diff-QuikEchantillons de lésions cutanées de 54 chiens. MATÉRIEL ET MÉTHODE: Etude I : la PCRq a été réalisée sur 19 lames (de 9 chiens) avec des amastigotes visibles à la cytologie. Quinze lames sans amastigote visible, obtenu de 12 chiens séronégatifs pour Leishmania par ELISA, ont servi de contrôle. Etude II : Une PCRq Leishmania a été réalisée sur des lames et FPI de lésions cutanées compatibles avec une leishmaniose clinique chez 33 chiens. RÉSULTATS: Etude I : toutes les lames avec amastigotes visibles avaient une PCRq positive tandis que les lames contrôles étaient négatives. Etude II : sur les 13 chiens diagnostiqués définitivement comme leishmaniose clinique, huit avaient des amastigotes visibles à la cytologie tandis que la PCRq Leishmania était positive sur 11 des lames et 13 FPI. LA leishmaniose a été exclue par méthodes standard chez 20 chiens, dont quatre présentaient une PCRq positive sur FPI et/ou lames.L’ADN de Leishmania peut être détectée efficacement par PCRq de cytologies cutanées et FPI pour le diagnostic de leishmaniose chez les chiens présentant des lésions cutanées évocatrices de CanL.INTRODUCCIÓN: la visualización de amastigotes permite la detección de Leishmania en lesiones cutáneas. La detección del DNA de Leishmania por PCR es más sensible, y la PCR se ha utilizado para diagnosticar la leishmaniasis cutánea en humanos utilizando muestras clínicas no invasivas. OBJETIVOS: Estudio I: determinar si el DNA de Leishmania se podría extraer y amplificar de manera eficiente a partir de preparaciones teñidas con Diff-Quik® archivadas de muestras citológicas de lesiones cutáneas caninas. Estudio II: evaluar el valor diagnóstico de una PCR cuantitativa (qPCR) de Leishmania en muestras citológicas teñidas y en impresiones de papel de filtro (FPI) obtenidas de lesiones cutáneas sugestivas de leishmaniasis canina (CanL). ANIMALES: muestras de lesiones cutáneas de 54 perros. MÉTODOS Y MATERIALES: Estudio I: se realizó qPCR para Leishmania en 19 portaobjetos de vidrio (de nueve perros) con amastigotes citológicamente visibles. Quince preparaciones sin amastigotes visibles, obtenidas de 12 perros seronegativos para Leishmania por ELISA, sirvieron como controles. Estudio II: se realizó qPCR para Leishmania en portaobjetos de vidrio y FPI de lesiones cutáneas compatibles con leishmaniasis clínica en 33 perros. RESULTADOS: Estudio I: todas las preparaciones con amastigotes visibles tuvieron qPCR positiva, mientras que todas las preparaciones de control dieron resultados negativos. Estudio II: de 13 perros diagnosticados definitivamente con leishmaniasis clínica, ocho tuvieron amastigotes visibles en la citología, mientras que qPCR para Leishmania fue positiva en 11 portaobjetos de vidrio y 13 FPI. La leishmaniasis se descartó mediante métodos estándar en 20 perros, cuatro de los cuales produjeron qPCR positiva en FPI y/o portaobjetos de vidrio. CONCLUSIONES E IMPORTANCIA CLÍNICA: la qPCR para DNA de Leishmania puede realizarse de forma efectiva a partir de muestras citológicas cutáneas y FPI para diagnosticar la infección por Leishmania en perros con lesiones cutáneas sugestivas de CanL.Leishmanien können in Hautveränderungen durch eine Sichtbarmachung der Amastigoten gefunden werde. Die Feststellung von Leishmania DNA mittels PCR bedeutet eine größere Sensibilität. Außerdem wurde die PCR verwendet, um kutane Leishmaniose bei Menschen mittels nichtinvasiver klinischer Proben zu diagnostizieren.Studie I: festzustellen, ob ausreichend Leishmania DNA aus archivierten Diff-Quick® gefärbten zytologischen Präparaten aus kutanen Veränderungen extrahiert und amplifiziert werden konnte. Studie II: eine Evaluierung der diagnostischen Leistung einer quantitativen Leishmania (q) PCR aus gefärbten Zytologiepräparaten sowie aus Abdrücken auf Filterpapier (FPI), die aus Hautveränderungen stammten, die verdächtig für eine canine Leishmaniose (CanL) waren.Es wurden Proben von Hautveränderungen von 54 Hunden verwendet.Studie I: Es wurde ein Leishmania-qPCR von 19 Objektträgern (von neun Hunden) mit zytologisch sichtbaren Amastigoten durchgeführt. Fünfzehn Objektträger ohne sichtbare Amastigoten, die von 12 Hunden stammten, die mittels ELISA seronegativ auf Leishmania waren, dienten als Kontrollen. Studie II: Ein Leishmania-qPCR wurde von Objektträgern und FPI kutaner Läsionen von 33 Hunden, die mit klinischer Leishmaniose kompatibel waren, durchgeführt.Studie I: alle Objektträger mit sichtbaren Amastigoten zeigten eine positive qPCR, während die Kontrollen ein negatives Ergebnis lieferten. Studie II: von den 13 Hunden, die definitiv mit einer Leishmaniose diagnostiziert worden waren, zeigten acht sichtbare Amastigoten in der Zytologie, während der Leishmania-PCR von 11 Objektträgern und 13 FPI positiv war. Eine Leishmaniose war bei 20 Hunden mit Standardmethoden ausgeschlossen worden, von denen vier eine positive qPCR von FPI und/oder Objektträgern lieferten.Leishmania-DNA kann effektiv mittels qPCR aus kutanen zytologischen Hautproben und aus FPI festgestellt werden, um eine Leishmania Infektion bei Hunden mit Hautveränderungen, die auf CanL hinweisen zu diagnostizieren.背景: 皮膚病変におけるリーシュマニアの検出は、無鞭毛期虫体の視覚化によって可能となる。 PCRによるリーシュマニアDNAの検出はより高い感度を示し、PCRは非侵襲性臨床標本を用いて人の皮膚リーシュマニア症を診断するために使用されてきた。 目的: 研究I:研究Iの目的は、犬の皮膚病変から得られた細胞学的標本のアーカイブされたDiff-Quik®染色スライドからLeishmania DNAを効率的に抽出および増幅できるかどうかを決定することである。研究II:研究IIの目的は、染色した細胞学的標本および犬リーシュマニア症(CanL)を示唆する皮膚病変から得られたfilter paper impressions (FPI)に対するリーシュマニア定量的(q)PCRの診断性能を評価することである。 被験動物: 54頭の犬の皮膚病変からのサンプル。 材料と方法: 研究I:Leishmania-qPCRを、細胞学的に観察可能な無鞭毛期虫体を含む19枚のスライドガラス(9頭の犬から)によって実施した。 ELISAによってリーシュマニアに対して血清陰性の12頭の犬から得られた、目に見える無鞭毛期虫体のない15枚のスライドを対照として用いた。研究II:33頭の犬において、リーシュマニアqPCRを、臨床的にリーシュマニア症と適合性のある皮膚病変からのスライドガラスおよびFPIに対して実施した。 結果: 研究I:目に見える無鞭毛期虫体を含む全てのスライドがqPCR陽性であったのに対し、全対照スライドは陰性結果をもたらした。研究II:臨床リーシュマニア症と確定診断された13頭の犬のうち、8頭が細胞診で目に見える斑点があったのに対し、Leishmania-qPCRは11枚のスライドガラスと13枚のFPIで陽性を示した。リーシュマニア症は、20頭の犬において標準的な方法で除外され、そのうちの4頭はFPIおよび/またはスライドガラス上でqPCR陽性を示した。 結論と臨床的重要性: リーシュマニアDNAは、CanLを示唆する皮膚病変を有する犬におけるリーシュマニア感染を診断するために、皮膚細胞診標本およびFPIからqPCRによって効率的に検出することができる。.背景: 通过发现无鞭毛体可以检测皮肤病变中的利什曼原虫。 PCR检测利什曼原虫DNA具有更高的灵敏度,并且无创临床样本的PCR检测已被用于诊断人类皮肤利什曼病。 目的: 研究I:确认是否能从已被Diff-Quik®染色的犬皮肤病变细胞学载玻片中,有效提取和扩增利什曼原虫DNA。研究II:染色细胞学和滤纸印迹(FPI)均采自疑似犬利什曼病(CanL)的皮肤病变,评估利什曼原虫定量(q)PCR方法对这些样本的诊断效果。 动物: 54只犬的皮肤病变样本。 方法和材料: 研究I:细胞学检查可见无鞭毛体的19张载玻片(来自9只犬),对其进行利什曼原虫-qPCR检测;从 12只犬身上获得的15张载玻片样本作为对照,细胞学检查未见无鞭毛体,经ELISA检测利什曼原虫血清阴性。研究II:33只症状符合利什曼病的犬,用利什曼原虫-qPCR法检测其皮肤病变载玻片和FPI。 结果: 研究I:所有可见无鞭毛体的载玻片,其qPCR检测均为阳性,而所有对照载玻片的检测结果均为阴性。 研究II: 13只确诊利什曼病的患犬中,8只细胞学上可见无鞭毛体,而利什曼原虫-qPCR检测中11张载玻片和13份FPI呈阳性。用标准方法排除利什曼病的20只犬中,经qPCR检测FPI和/或载玻片,有4只呈阳性。 结论和临床价值: 用qPCR技术检测皮肤细胞学和FPI中的利什曼原虫DNA,可有效诊断皮肤病变疑似CanL的利什曼原虫感染。.A detecção de Leishmania em lesões cutâneas é possível pela visualização de amastigotas. A detecção de DNA de Leishmania por PCR possui maior sensibilidade, e a PCR tem sido utilizada para diagnosticar leishmaniose cutânea em humanos utilizando espécimens clínicos não invasivos.Estudo I: determinar se o DNA de Leishmania pode ser eficientemente extraído e amplificado de lâminas coradas em Diff-QuikAmostras cutâneas de lesões de 54 cães. MÉTODOS E MATERIAIS: Estudo I: Leishmania-qPCR foi realizado em 19 lâminas de vidro (de nove cães) com amastigotas citologicamente visíveis. Quinze lâminas sem amastigotas visíveis, obtidas de 12 cães soronegativos para Leishmania por ELISA serviram como controle. Estudo II: Leishmania-qPCR foi realizado em lâminas de vidro e em FPI de lesões cutâneas compatíveis com leishmaniose clínica em 33 cães.Estudo I: todas as amostras com amastigotas visíveis apresentaram qPCR positivo, enquanto todas as lâminas controle tiveram resultados negativos. Estudo II: dos 13 cães diagnosticados definitivamente com leishmaniose clínica, oito apresentaram amastigotas visíveis na citologia, enquanto Leishmania-qPCR foi positivo em 11 lâminas de vidro e 13 FPI. Descartou-se a leishmaniose pelos métodos convencionais em 20 cães, dos quais quatro apresentaram qPCR positiva na FPI e/ou nas lâminas de vidro. CONCLUSÕES E IMPORTÂNCIA CLÍNICA: O DNA de Leishmania pode ser eficientemente detectado por qPCR de espécimens citológicos cutâneos e FPI para diagnosticar uma infecção por Leishmania em cães com lesões cutâneas sugestivas de CanL.

Background Canine leishmaniosis (CanL) caused by Leishmania infantum can have several dermatological manifestations. The type of immune response elicited against the parasite appears to be at the basis for such clinical variability. Much of the work in CanL has focused on adaptive immune response and there are scarce data on the importance of the innate immune responses. Moreover, few studies have evaluated the immunological response in the cutaneous lesions in dogs naturally infected with L. infantum and with different degrees of disease severity, and no study has compared clinically-lesioned with normal-looking skin. Methods We determined and compared the transcription of toll like receptors (TLRs) 2, 4 and 7, interferon gamma (IFN-γ), interleukin (IL) 10 and programmed cell death protein ligand (PD-L) 1 by real-time PCR in paired clinically-lesioned and normal-looking skin from 25 diseased dogs (mild disease-stage I (n = 11) and moderate to severe disease-stages II and III (n = 14) as well as in normal-looking skin from healthy dogs (n = 10) from a non-endemic area. We also assessed the association between the transcripts in clinically-lesioned and normal-looking skin of dogs with leishmaniosis with clinicopathological, immunological and parasitological findings. Results Clinically-lesioned skin from mildly affected dogs was characterized by a significant upregulation of TLR2 (P P = 0.021) and downregulation of TLR7 (P = 0.004) when compared with more severely affected dogs. Normal-looking skin of mildly affected dogs was characterized by a significant lower expression of TLR7 (P = 0.003), IFN-γ (P P = 0.001) when compared with more severely affected dogs. TLR2, TLR4, IL-10 and IFN-γ upregulation in clinically-lesioned skin was correlated with lower disease severity while TLR7 upregulation was correlated with markers of disease severity. Upregulation of TLR7, IL-10, IFN-γ and PD-L1 in normal-looking skin was correlated with disease severity. Conclusions This study demonstrated different expression profiles of immune genes in clinically-lesioned and normal-looking skin among mildly and more severely affected dogs. These immunological conditions might favor the maintenance and replication of the parasite in the skin of more severely affected dogs.

Innate immunity, in particular, the role of toll-like receptors (TLRs), has not been extensively studied in canine L. infantum infection. The main aim of this study was to determine the transcription of TLR2 and TLR4 in the blood of dogs with natural clinical leishmaniosis at the time of diagnosis and during treatment follow-up and subsequently correlate these findings with clinical, serological and parasitological data. Forty-six Leishmania-seropositive sick dogs with a high antibody level at the time of diagnosis were studied and compared with 34 healthy seronegative dogs. Twenty-two of these sick dogs were treated with meglumine antimoniate and allopurinol and followed-up at 30, 180 and 365days following the start of treatment. Clinical status was defined by a thorough physical examination, complete blood count, biochemistry profile, electrophoresis of serum proteins, and urinary protein/creatinine ratio (UPC). EDTA blood was stored in RNAlater® solution before RNA extraction and cDNA production were performed. TLR2, TLR4 and three reference genes (HPRT-1, CG14980 and SDHA) were studied in each blood sample by real time PCR. The relative quantification of TLR2 was higher (mean 3.5) in sick dogs when compared with seronegative healthy dogs (mean 1.3; P=0.0001) while the relative quantification of TLR4 was similar in both groups. In addition, the relative quantification of TLR2 significantly decreased during follow-up at all time points compared with day 0 whereas no changes were observed with TLR4 transcription. A significant positive correlation was noted between TLR2 and UPC, total protein, beta and gamma globulins, specific L. infantum antibodies and blood parasite load while a negative correlation was observed with albumin, albumin/globulin ratio, hematocrit and hemoglobin. TLR4 transcript did not correlate with any parameter. These findings indicate an up-regulation of TLR2 transcription in unstimulated blood in naturally infected sick dogs as compared to healthy dogs suggesting active innate immune and proinflammatory responses. In addition, TLR2 transcription is reduced with clinical improvement during treatment. In contrast, TLR4 transcription appears to be similar among groups at the time of diagnosis with no changes during treatment follow-up suggesting a less important role for this TLR in clinical canine leishmaniosis.

Venezuela is a country where human and canine leishmaniosis due to Leishmania infantum, Leishmania braziliensis and other Leishmania spp. is endemic. However, only limited data is available on canine Leishmania infection in Venezuela. The aim of this cross-sectional study was to evaluate the prevalence of Leishmania infection in dogs (n = 152) from the states of Lara (n = 91) and Yaracuy (n = 61) in Venezuela by means of serological and molecular methods. Physical examination was performed and blood samples were collected from all dogs. Serology for antibodies reactive with L. infantum and L. braziliensis antigens was assessed by the enzyme-linked immunosorbent assay (ELISA) and detection of Leishmania DNA from blood samples was evaluated by kinetoplast Leishmania real-time polymerase chain reaction (RT-PCR). In addition, Leishmania internal transcribed spacer (ITS-1) RT-PCR was performed on the samples positive by kinetoplast RT-PCR. The prevalence of Leishmania infection based on serological and/or molecular techniques was 11.8%. The seroprevalence for L. infantum and L. braziliensis antigens were 2.1% (3/144) and 8.3% (12/144), respectively. All dogs from the state of Yaracuy were serologically negative to L. infantum while 4.6% (4/86) of the dogs were reactive to L. braziliensis antigen. Fourteen percent (8/58) of the dogs from the state of Lara were positive to L. infantum and 5.2% (3/58) to L. braziliensis antigen. Three dogs were positive to both Leishmania spp. antigens. By RT-PCR, 6.5% (4/61) and 4.4% (4/91) of the dogs were positive for infection in the states of Lara and Yaracuy, respectively. The RT-PCR product of one dog from the state of Yaracuy was sequenced revealing a 100% identity with L. infantum. However, all RT-PCR positive dogs were seronegative to both Leishmania spp. antigens. In conclusion, the positivity for Leishmania spp. infections observed indicates that dogs are frequently infected by L. infantum, L. braziliensis or related Leishmania spp. in Venezuela.

Activation of toll-like receptors (TLRs) has been shown to play an important role in leishmaniosis by enhancing the parasite specific immune responses to control infection. However, the role of TLR agonists has not been studied in detail in dogs. The aim of this study was to determine the effect of TLR3, TLR4, and TLR7 agonists (TLR3a, TLR4a, and TLR7a) alone or in combination withLeishmania infantumantigen (LSA) on TNF-αand IL-6 production in blood from dogs living in endemic areas of canine leishmaniosis (CanL). Twenty-four healthy dogs from Catalonia (n=14) and Ibizan hound dogs from the island of Mallorca (n=10) were enrolled. Whole blood with TLR3a, TLR4a, and TLR7a alone or combined with LSA were cultured separately, and IFN-γ, TNF-α, and IL-6 were measured by ELISA. A significant increase of TNF-αwas found for all conditions studied compared to medium alone. Stimulation with TLR4a(p=0.0001)and TLR7a(p=0.005)presented a significantly marked increase in TNF-αand IL-6 production compared to TLR3a. Importantly, significantly higher TNF-αproduction was found in LSA+TLR4a(p=0.0001)stimulated blood and LSA+TLR7a(p=0.005)compared to LSA alone. All dogs showed higher TNF-αproduction after LSA+TLR7a compared to TLR7a(p=0.047)and LSA+TLR3a compared to TLR3a(p=0.052). These data indicate a marked inflammatory cytokine effect of TLR4a and TLR7a on blood from healthy dogs living in endemic areas of CanL. Additionally, LSA+TLR7a promoted a synergistic proinflammatory effect with TNF-αin all dogs. Those findings suggest an active role of TLRs in proinflammatory responses, which might be strongly involved in the process of disease resolution.

Background: Venezuela is an endemic area for human and canine leishmaniosis due to Leishmania infantum and parasites of the Leishmania braziliensis and L. mexicana complexes. Limited data are available on feline leishmaniosis (FeL) in this region. The aim of this study was to describe clinical and diagnostic aspects of FeL in Venezuela. Results: Thirty-one domestic cats from urban areas of Lara State in Venezuela were enrolled. Twenty-five were healthy. Six other cats had solitary or multiple nodular lesions, which were located on the nose; ears; ears and nose; and nose, ears, tail and lower limbs. Cutaneous lesions were characterized by diffuse pyogranulomatous infiltrate in all sick cats with numerous intracellular and extracellular amastigotes, and immunohistochemistry was positive for Leishmania in five sick cats. All healthy cats were seronegative for L. infantum and L. braziliensis antigens by ELISA. Two out of five sick cats yielded a positive ELISA result to both Leishmania antigens with higher antibody levels to L. braziliensis compared to L. infantum. Significantly higher antibody levels by ELISA as well as a higher number of bands by Western blot (WB) were found for L. braziliensis when compared to L. infantum antigens in all sera from Venezuelan sick and healthy cats. All healthy cats were blood Leishmania spp. qPCR negative while three out of six sick cats were blood qPCR positive. All paraffin-embedded skin biopsies (n = 4) as well as cutaneous cytology (n = 3) were positive by Leishmania spp. qPCR in sick cats. Leishmania speciation was obtained only from the cutaneous lesion samples from cytological preparations of two out of three sick cats which were identified as infected with L. mexicana or a closely related specie. Conclusions: FeL should be included in the differential diagnosis list of nodular-ulcerative lesions. The most reliable diagnostic technique in sick cats is cytological or histopathological examination along with immunohistochemistry, since blood PCR and serology by ELISA might be negative. WB appears to be more sensitive in detecting infection. Cats with leishmaniosis from Venezuela are most likely infected with species of L. mexicana or a closely related species or the L. braziliensis species complex and not with L. infantum.

Canine leishmaniosis has a wide range of disease severity from mild (stage I), to severe (stages II-III), or very severe disease (stage IV). The objective of the study was to evaluate and compare serum antibody levels, Leishmania infantum specific IFN- γ production and TLR2 and TLR4 transcripts in non-stimulated blood from dogs with different clinical stages at the time of diagnosis as well as blood parasitemia. Enzyme-Linked ImmunoSorbent Assay (ELISAs) were performed to determine serum antibody levels and IFN- γ production and quantitative polymerase chain reaction (qPCRs) in order to determine blood parasite load and TLR2 and TLR4 transcripts. Older dogs were significantly affected by more severe disease with higher antibody levels and blood parasitemia than dogs with mild disease. IFN- γ production was significantly higher in dogs with stage I disease when compared to dogs with more severe disease. Relative quantification of TLR2 in dogs with mild disease was similar to that of control dogs. On the other hand, TLR2 transcripts were significantly higher in dogs with severe disease as compared with that from control healthy dogs. No differences were found in TLR4 relative quantification between groups. This study demonstrates that dogs with different clinical stages of leishmaniosis present different levels of biological markers indicative of different immune responses.

The severity of canine leishmaniosis (CanL) due to Leishmania infantum might be affected by other vector-borne organisms that mimic its clinical signs and clinicopathological abnormalities. The aim of this study was to determine co-infections with other vector-borne pathogens based on serological and molecular techniques in dogs with clinical leishmaniosis living in Spain and to associate them with clinical signs and clinicopathological abnormalities as well as disease severity. Sixty-one dogs with clinical leishmaniosis and 16 apparently healthy dogs were tested for Rickettsia conorii, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae antigens by the immunofluorescence antibody test (IFAT) and for E. canis, Anaplasma spp., Hepatozoon spp., Babesia spp. and filarioid DNA by polymerase chain reaction (PCR). Among the dogs examined by IFAT, the seroprevalences were: 69% for R. conorii, 57% for E. canis, 44% for A. phagocytophilum and 37% for B. henselae; while the prevalences found by PCR were: 8% for Ehrlichia/Anaplasma, 3% for Anaplasma platys and 1% for H. canis. No other pathogen DNA was detected. Statistical association was found between dogs with clinical leishmaniosis and seroreactivity to R. conorii antigen (Fisher’s exact test: P = 0.025, OR = 4.1, 95% CI = 1–17) and A. phagocytophilum antigen (Fisher’s exact test: P = 0.002, OR = 14.3, 95% CI = 2–626) and being positive to more than one serological or molecular tests (co-infections) (Mann-Whitney test: U = 243, Z = -2.6, n 1 = 14, n 2 = 61, P = 0.01) when compared with healthy dogs. Interestingly, a statistical association was found between the presence of R. conorii, E. canis, A. phagocytophilum and B. henselae antibodies in sick dogs and some clinicopathological abnormalities such as albumin and albumin/globulin ratio decrease and increase in serum globulins. Furthermore, seroreactivity with A. phagocytophilum antigens was statistically associated with CanL clinical stages III and IV. This study demonstrates that dogs with clinical leishmaniosis from Catalonia (Spain) have a higher rate of co-infections with other vector-borne pathogens when compared with healthy controls. Furthermore, positivity to some vector-borne pathogens was associated with more marked clinicopathological abnormalities as well as disease severity with CanL.

There is limited data regarding Leishmania infantum specific T cell mediated immunity in naturally infected sick dogs at the time of diagnosis and during anti-Leishmania treatment. Our aim was to investigate the kinetics of L. infantum specific IFN-γ production in dogs with leishmaniosis at the time of diagnosis and during treatment and to correlate it with specific L. infantum antibodies, blood parasitemia and clinicopathological findings. Thirty-four dogs were diagnosed with leishmaniosis based on physical examination, routine laboratory tests and L. infantum-specific antibody levels by quantitative ELISA. Heparinized whole blood was stimulated with L. infantum soluble antigen (LSA) and concanavalin A (ConA) and incubated for 5 days. IFN-γ concentration was evaluated in supernatants of stimulated blood using a commercial sandwich ELISA. Leishmania real-time PCR was also performed for assessing blood parasitemia. Dogs were treated with meglumine antimoniate and allopurinol. Sixteen dogs were classified as IFN-γ non-producers after LSA stimulation (mean ± SD: 0 ± 0 pg/mL) and 18 dogs as IFN-γ producers (mean ± SD: 2885.3 ± 4436.1 pg/mL) at the time of diagnosis (P < 0.0001). IFN-γ non-producers were classified in a more severe clinical staging than IFN-γ producers that presented a mild to moderate clinical staging (P = 0.03). In the IFN-γ non-producer group, production of IFN-γ after LSA stimulation was significantly increased during treatment especially at day 365 (P = 0.018) together with clinical improvement when compared with day 0. In contrast, IFN-γ producers maintained their IFN-γ production after LSA stimulation and no statistically significant changes were found during treatment follow-up. At diagnosis, IFN-γ non-producers showed a significantly higher blood parasitemia versus IFN-γ -producers (P = 0.005). IFN-γ non-producers drastically reduced blood parasitemia to minimum values at day 365 when compared with day 0 (P = 0.017). No significant differences were found at day 365 in blood parasitemia of IFN-γ producers compared to pre-treatment. At diagnosis, L. infantum specific antibodies were higher in IFN-γ non-producers than IFN-γ producers (P = 0.014). A marked reduction of antibody levels was found at day 365 when compared with day 0 in IFN-γ non-producers (P = 0.005) and producers (P = 0.001). These results demonstrate that IFN-γ concentration increases with long-term anti-Leishmania treatment together with clinical improvement in dogs that do not produce IFN-γ at diagnosis. Together with clinical recovery, reduction in blood parasitemia and L. infantum specific antibodies, tracking IFN-γ concentration could constitute an important prognostic tool for immune monitoring in CanL.

Summary The leishmanin skin test (LST), a delayed-type hypersensitivity (DTH) reaction to Leishmania infantum, can specifically identify dogs that have made a cell-mediated immune response to L. infantum infection. The Ibizan hound appears to be more resistant to L. infantum infection than other breeds of dog. The aim of this study was to describe the histological and immunohistochemical changes induced by the LST in Ibizan hounds living in an area highly endemic for leishmaniosis. The majority of dogs were apparently healthy, lacked serum antibody to L. infantum and blood parasitaemia, but had marked specific interferon gamma production after in-vitro blood stimulation with L. infantum. Leishmanin (3 × 108 killed promastigotes of L. infantum/ml) was injected intradermally and biopsy samples were obtained from a positive reaction at 72 h from nine Ibizan hounds. A moderate to intense, perivascular to interstitial dermatitis and panniculitis characterized the inflammatory response at the injection site. In addition, three samples had diffuse inflammation in the deep dermis and panniculus. Oedema and necrosis were present in the deep dermis and panniculus. Congestion and haemorrhage were observed in five biopsies. T lymphocytes (CD3+) and large mononuclear cells (lysozyme−) were the most prevalent cells. CD3+ cells were significantly more numerous than CD20+ B cells and lysozyme+ cells. B cells were sparsely distributed, especially in the deep dermis and panniculus. Rare neutrophils and macrophages (lysozyme+) were observed with few eosinophils. Toll-like receptor (TLR)-2 protein was expressed in large mononuclear cells mainly located in the superficial dermis. Leishmania immunohistochemistry was negative and quantitative polymerase chain reaction was positive in all cases. The intradermal injection of killed L. infantum promastigotes in Ibizan hounds causes similar histological and immunohistochemical findings to those described for human subjects and are indicative of a DTH response. Moreover, TLR2 protein is expressed in inflammatory cells similar to findings in clinically affected skin biopsy samples.

Background There is limited information available on cytokine profiles in dogs with different degrees of disease severity due to natural infection of Leishmania infantum. The aim of this study was to investigate L. infantum-specific IFN-γ and IL-10 production in blood from dogs with leishmaniosis at diagnosis and correlate these findings with disease severity, humoral immune response and blood parasitemia. Methods Sixty dogs were diagnosed based on physical examination, routine laboratory tests, L. infantum-specific antibody levels measured by quantitative ELISA and blood parasitemia by real-time PCR. Heparin whole blood was stimulated with L. infantum soluble antigen (LSA) and concanavalin A (ConA) and incubated for 5 days. IFN-γ and IL-10 concentrations were measured in supernatants with sandwich ELISAs. Results The majority of dogs (n = 36) were classified as LeishVet stage II (moderate disease). The rest of the dogs were classified as stage I (n = 10), III (n = 10) and IV (n = 4). Dogs classified with stage I and IIa presented significantly higher (P = 0.02) LSA IFN-γ concentrations, lower (P

Background Normal-looking skin of dogs with leishmaniosis frequently shows microscopic lesions along with the presence of Leishmania amastigotes. However, histological lesions with or without detection of amastigotes might not occur in less severe clinical cases. In addition, comparative studies between paired clinically-lesioned and normal-looking skin samples from dogs with different disease severity are lacking. The objective of this study was to compare histological and parasitological findings by Leishmania immunohistochemistry (IHC) and quantitative PCR (qPCR) on paired clinically-lesioned and normal-looking skin biopsies from 25 dogs with different clinical stages of leishmaniosis, 11 with stage I-mild disease (papular dermatitis) and 14 with stage II-III (ulcerative or exfoliative dermatitis). Results The study demonstrated microscopic lesions in 14 out of 25 (56%) samples from normal-looking skin biopsies. In those samples, perivascular to interstitial dermatitis composed by macrophages with lymphocytes and plasma cells was observed mainly in the superficial and mid-dermis. The intensity of the dermatitis was mild to moderate and always less prominent than in the clinically-lesioned skin. In normal-looking skin samples, the presence of parasites was detected by histology, IHC and qPCR in 5/25 (20%), 8/25 (32%) and 18/25 (72%), respectively. Leishmania was encountered in 11/25 (44%), 23/25 (92%) and 25/25 (100%) of clinically-lesioned skin samples by histology, IHC and qPCR, respectively. Normal-looking skin from dogs with stage I-mild disease was less frequently inflamed (P = 0.0172). Furthermore, Leishmania was more easily demonstrated by histology (P = 0.0464), IHC (P = 0.0421) or qPCR (P = 0.0068) in normal-looking skin of dogs with stage II-III-moderate to severe disease. In addition, in the latter group, there was a significantly higher parasite load studied by means of qPCR than in dogs with less severe disease (P = 0.043). Clinically-lesioned skin from dogs with stage I disease was more frequently characterised by the nodular to diffuse pattern and granuloma formation (P = 0.0166) and by a lower parasite load studied by means of qPCR (P = 0.043) compared with more diseased dogs. Conclusions Normal-looking skin from dogs with stage I is less likely to present histological lesions as well as harbour the parasite when compared with dogs with moderate to severe leishmaniosis.