Nucleotides and AHCC Enhance Th1 Responses In Vitro in Leishmania-Stimulated/Infected Murine Cells

Efficacy of a combination of nucleotides and lactoferrin in maintaining stable or improving the clinical picture and laboratory findings of leishmaniotic dogs: A randomized controlled study

This prospective, randomized, controlled, therapeutic study aimed to evaluate the efficacy of a product containing nucleotides and lactoferrin in maintaining or improving the clinical picture and laboratory findings of canine leishmaniosis (CanL). The safety and tolerance of this combination were also assessed. Forty Leishmania infantum-seropositive dogs, not requiring leishmanicidal and/or leishmaniostatic treatment, were enrolled in the study and randomized into treatment (TG) and placebo (CG) groups. Products A (containing nucleotides and lactoferrin) and B (placebo) were blindly administered to TG and CG, respectively, as palatable tablets at a rate of 1 tablet per 10 kg of weight once every 24 h for 6 months. Following inclusion (T0), dogs were followed up after 3 (T90) and 6 (T180) months. At each time point, for all animals enrolled physical examination and laboratory tests (complete blood count, biochemical panel including C-reactive protein [CRP] and ferritin, and serum protein electrophoresis) were performed. The immunofluorescence antibody test to detect antibodies for L. infantum (T0, T180), Ehrlichia canis (T0, T90, and T180), and Anaplasma phagocytophilum (T0, T90, and T180) was executed. A CanL-dedicated clinical score, using a validated scale from 0 (i.e., absence of clinical signs) to 19, was assigned. Four dogs (n=2 in TG, n=2 in CG) did not complete the study. No statistically significant differences in CanL clinical score were observed between CG and TG at T0, T90 and T180. Both TG and CG showed significant variations in anti-L. infantum antibody titres (p=0.0001 and p=0.004, respectively). In TG, antibody titres decreased in 77.8 %, increased in 5.5 %, and remained stable in 16.7 % of dogs, while in CG, decreased in 27.8 %, increased in 50 %, and remained stable in 22.2 % of dogs. During the study, CRP and ferritin remained stable in TG and significantly increased in CG. At T180, 9 out of 18 dogs (50 %) enrolled in the CG, and 1 out of 18 (5.6 %) enrolled in the TG, developed an active form of leishmaniosis. No side effects were reported in any patient included. In conclusion, a 6-month oral administration of a supplement containing nucleotides and lactoferrin was effective in maintaining a stable clinical score, improving antibody titres and potentially reducing the progression from non-active to active forms in L. infatum seropositive dogs. Furthermore, the product was well-tolerated, easy to administer, and free of side effects.

Clinical validation of circulating immune complexes for use as a diagnostic marker of canine leishmaniosis

Introduction

Canine leishmaniosis (CanL) is a systemic disease that affects dogs. When multiplication of the parasite cannot be controlled, dogs consistently show high levels of antigen and IgG antibodies, which lead to the formation of circulating immune complexes (CIC). Timely intervention to reduce the parasite load and CIC levels is crucial for preventing irreversible organ damage. However, a diagnostic test to quantify CIC levels is currently lacking.

Methods

In this real-world study, we aimed to examine the performance of a new ELISA to measure CIC levels in dogs naturally infected with Leishmania infantum. Thirty-four dogs were treated according to their clinical condition and followed for 360 days. Before (day 0) and after treatment (days 30, 90, 180, 270, and 360), all dogs underwent a physical examination, and blood samples were obtained for CBC, biochemical profile, serum protein electrophoresis and IFAT. Serum PEG-precipitated CIC were determined by ELISA.

Results

Our results indicate higher CIC levels in dogs in advanced disease stages showing higher antibody titres (p < 0.0001, r = 0.735), anemia (p < 0.0001), dysproteinemia (p < 0.0001), and proteinuria (p = 0.004). Importantly, dogs responding well to treatment exhibited declining CIC levels (p < 0.0001), while in poor responders and those experiencing relapses, CIC were consistently elevated. CIC emerged as a robust discriminator of relapse, with an area under the curve (AUC) of 0.808. The optimal cut-off to accurately identify relapse was an optical density of 1.539.

Discussion

Our findings suggest that declining CIC levels should be expected in dogs showing a favorable treatment response. Conversely, in dogs displaying a poor response and recurrent clinical relapses, CIC levels will be high, emphasizing the need for vigilant monitoring. These findings suggest that CIC could serve as a valuable biomarker for disease progression, treatment efficacy, and relapse detection in CanL. Our study contributes to enhancing diagnostic approaches for CanL and underscores the potential of CIC as a complementary tool in veterinary practice. As we move forward, larger studies will be essential to confirm these findings and establish definitive cut-offs for clinical application.

Effect of Local Administration of Meglumine Antimoniate and Polyhexamethylene Biguanide Alone or in Combination with a Toll-like Receptor 4 Agonist for the Treatment of Papular Dermatitis due to Leishmania infantum in Dogs

Papular dermatitis is a cutaneous manifestation of canine Leishmania infantum infection associated with mild disease. Although it is a typical presentation, nowadays, there is still no established treatment. This study evaluated the safety and clinical efficacy of local meglumine antimoniate, locally administered polyhexamethylene biguanide (PHMB) alone or PHMB in combination with a Toll-like receptor 4 agonist (TLR4a) for the treatment of papular dermatitis due to L. infantum and assessed parasitological and immunological markers in this disease. Twenty-eight dogs with papular dermatitis were divided randomly into four different groups; three of them were considered treatment groups: PHMB (n = 5), PHMB + TLR4a (n = 4), and meglumine antimoniate (n = 10)), and the remaining were considered the placebo group (n = 9), which was further subdivided into two sub-groups: diluent (n = 5) and TLR4a (n = 4). Dogs were treated locally every 12 h for four weeks. Compared to placebo, local administration of PHMB (alone or with TLR4a) showed a higher tendency towards resolution of papular dermatitis due to L. infantum infection at day 15 (χ² = 5.78; df = 2, p = 0.06) and day 30 (χ² = 4.; df = 2, p = 0.12), while local meglumine antimoniate administration demonstrated the fastest clinical resolution after 15 (χ² = 12.58; df = 2, p = 0.002) and 30 days post-treatment (χ² = 9.47; df = 2, p = 0.009). Meglumine antimoniate showed a higher tendency towards resolution at day 30 when compared with PHMB (alone or with TLR4a) (χ² = 4.74; df = 2, p = 0.09). In conclusion, the local administration of meglumine antimoniate appears to be safe and clinically efficient for the treatment of canine papular dermatitis due to L. infantum infection.

Nutritional Modulation of the Immune Response Mediated by Nucleotides in Canine Leishmaniosis

Leishmaniasis is an emerging, uncontrolled, and neglected zoonotic disease. Climate change is contributing to its ongoing global expansion. The dog is the main reservoir; hence the importance of implementing effective treatment, prevention, and control measures in this animal species to protect public health. However, although the standard treatment for canine leishmaniosis (CanL) is effective, it does not provide full parasitological clearance, and side effects and drug resistance have been described. The host's immune system plays a key role in the establishment and evolution of leishmaniasis. Dietary nucleotides modulate the immune response and, given their reported efficacy and safety in sick and clinically healthy Leishmania-infected dogs and because they represent a sustainable option with no associated side effects or resistance, they could be included within the prevention, treatment, and control strategies for leishmaniasis. This article briefly summarizes the scientific literature on CanL management, including unresolved issues, and reviews the scientific evidence on immunomodulatory effects of dietary nucleotides in different animal species. It also proposes a CanL management algorithm, including nucleotides. It is concluded that nutritional modulation of the immune response with nucleotides can contribute to better management of leishmaniasis following a One Health approach, especially in the COVID-19 era.