Perturbation of the T cell receptor repertoire occurs with increasing age in dogs

Detection of HHV-5 HHV-6a HHV-6b and HHV-7 in the urine: potential use as a non-invasive diagnostic tool for immune profiling

Decline in immune function with age has been studied extensively, but approaches to immune restoration have been hampered by the lack of simple methods of identifying individuals whose immune system is in decline. Our approach has been to identify individuals whose immune decline has led to a loss of control of common latent viral infections and their consequent reactivation. Viruses excreted in urine were detected and quantified and we believe this approach could provide a 'surrogate marker' for identifying immune compromised individuals. Here we report the detection of human herpes virus (HHV) 5, 6a, 6b and 7 in the urine of healthy individuals over a wide age range and their correlation with T cell receptor excision circle (TREC) data. The results did not show a clear correlation between TREC values and the detection of individual specific viruses or viral load values when measured singly. However, a correlation was found between low TREC values and the detection of several different human herpes viruses in the urine in males. We present evidence suggesting that for males, the detection of three or more different human herpes viruses in the urine could identify individuals with declining immune function as evidenced by their significantly lower TREC levels.

Effects of ashwagandha (Withania somnifera) root extract on aging-related changes in healthy geriatric dogs: A randomized, double-blinded placebo-controlled study

BACKGROUND AND AIM

This study aimed to explore the clinical potential of Withania somnifera/ashwagandha root extract (ARE) to mitigate age-related changes in healthy geriatric dogs. We hypothesized that ARE can reduce the effects of advancing age, including physiological changes, immune response decline and susceptibility to diseases, by its immunomodulatory effects.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted in Telangana, India, from July 2022 to September 2022. Twenty apparently healthy dogs, aged 8 years or older, were enrolled. The dogs were divided into two groups to receive ARE (15 mg/kg, once daily, orally) or a placebo control. Various parameters, including serum cortisol levels, haematological profiles, biochemical markers, antioxidant indicators and anti-inflammatory responses, were assessed at the initiation of study, day 30, and day 60.

RESULTS

The erythrocyte count and haemoglobin levels were significantly increased with ARE (p < 0.001), whereas leukocyte count decreased (p < 0.05). Moreover, significant decreases in important markers of liver function (alanine aminotransferase, aspartate aminotransferase, albumin and globulin; p < 0.001 at day 60), as well as kidney function markers (creatinine and blood urea nitrogen; p < 0.001 at days 30 and 60), were observed in ARE-treated dogs compared to the placebo control group. In addition, the levels of markers of oxidative stress (superoxide dismutase, catalase, glutathione and malondialdehyde) were significantly modulated by ARE intervention, indicating strong antioxidant effects. Interestingly, serum cortisol levels reduced significantly with ARE (p < 0.001). Compared to baseline, ARE significantly decreased key inflammatory markers, including interferon-γ, tumour necrosis factor-α, nuclear factor kappa light chain enhancer of activated B cells and interleukin-10 (p < 0.001) levels at day 60.

CONCLUSION

In conclusion, the findings of this study suggest that ARE has adaptogenic properties in healthy geriatric dogs by improving haematological and biochemical profiles, enhancing antioxidant defence, reducing stress and modulating inflammatory responses.

Development of a next-generation sequencing protocol for the canine T cell receptor beta chain repertoire

Profiling the T cell receptor (TCR) repertoire using next-generation sequencing has become common in both human and translational research. Companion dogs with spontaneous tumors, including canine melanoma, share several features, e.g., natural occurrence, shared environmental exposures, natural outbred population, and immunocompetence. T cells play an important role in the adaptive immune system by recognizing specific antigens via a surface TCR. As such, understanding the canine T cell response to vaccines, cancer, immunotherapies, and infectious diseases is critically important for both dog and human health. Off-the-shelf commercial reagents, kits and services are readily available for human, non-human primate, and mouse in this context. However, these resources are limited for the canine. In this study, we present a cost-effective protocol for analysis of canine TCR beta chain genes. Workflow can be accomplished in 1-2 days starting with total RNA and resulting in libraries ready for sequencing on Illumina platforms.

Profiling T cell receptor β-chain in responders after immunization with recombinant hepatitis B vaccine

BACKGROUND

T cells with edited T cell receptor β-chain variable (TRBV) are involved in the immune response to recombinant hepatitis B surface antigen (rHBsAg) vaccine and the production of hepatitis B surface antibody (HBsAb). The immune repertoire (IR) profile and mechanism of vaccination positive responders (VPR) with rHBsAg are not fully understood.

METHODS

The IR of six VPRs (HBsAb+, HbsAg-) with rHBsAg vaccination was established by the high throughput sequencing technique and bioinformatics analysis and compared with those in five vaccination negative responders (VNRs) (HbsAb-, HbsAg-) who were also inoculated with rHBsAg. The repertoire features of the BV, BJ and V (CDR3) J genes and immune diversity in peripheral blood mononuclear cells, respectively, were analyzed for each subject.

RESULTS

There was no significant difference in sequencing amplification indices of each sample. However, TRBV15/BJ2-3 demonstrated significantly high expression levels in VPR compared to those in the VNR group (both p < 0.05). Further results showed that the BV15/BJ2-5 level was significantly increased for VPR compared to that of VNR group. Interestingly, the motif of CDR3 in TRBV15/BJ2-5 was mostly expressed as "GGETQ" or "GETQ". Additionally, there was no remarkable difference between the two groups of distribution with respect to the different clone expression levels of V (CDR3) J.

CONCLUSIONS

The features of IR in the VPR and VNR will contribute to the exploration of the mechanism of the positive response to rHBsAg, and also contribute to development of optimized hepatitis B vaccine, in addition to providing a partial interpretation of the VNR who has a relatively low infection with HBV.

Is signalment associated with clinicopathological findings in dogs with leishmaniosis?

BACKGROUND

Canine leishmaniosis (CanL) is a common infectious disease. Age, sex and breed might influence the type of clinical and pathological manifestations that dogs develop. The main objective of this retrospective cross-sectional study was to determine if an association between age, sex, breed and size and the clinical findings of CanL exists.

MATERIAL AND METHODS

Dogs with a diagnosis of leishmaniosis were enrolled (n = 123). Clinical information, including signalment, clinical signs and laboratory abnormalities, was retrieved from medical records from different veterinary facilities from Catalonia.

RESULTS

Young dogs developed less frequently systemic signs (p = 0.0046), renal (p = 0.0019) and haematologic (p = 0.0275) abnormalities, while dermatologic signs were more common in young and adult dogs compared with old ones (p = 0.0451). Young dogs showed proteinuria less often than adult and old dogs (p = 0.0029). Young dogs did not present renal azotemia, while old dogs showed occasionally renal azotemia (p = 0.0478). Young dogs were mainly classified as mild-moderate LeishVet clinical stages of the disease, and very rarely as severe-very severe LeishVet clinical stages, compared with adult and old dogs (p = 0.0457). Purebred dogs significantly developed ulcerative dermatitis more frequently than crossbred dogs (p = 0.0460).

CONCLUSION

This study describes that age is associated with differences in clinicopathological findings of CanL.

Aging and Options to Halt Declining Immunity to Virus Infections

Immunosenescence is a process associated with aging that leads to dysregulation of cells of innate and adaptive immunity, which may become dysfunctional. Consequently, older adults show increased severity of viral and bacterial infections and impaired responses to vaccinations. A better understanding of the process of immunosenescence will aid the development of novel strategies to boost the immune system in older adults. In this review, we focus on major alterations of the immune system triggered by aging, and address the effect of chronic viral infections, effectiveness of vaccination of older adults and strategies to improve immune function in this vulnerable age group.

Development of Dog Immune System: From in Uterus to Elderly

Immune system recognize and fight back foreign microorganisms and inner modifications that lead to deficient cell and tissue functions. During a dog's life, the immune system needs to adapt to different physiological conditions, assuring surveillance and protection in a careful and controlled way. Pregnancy alters normal homeostasis, requiring a balance between immunity and tolerance. The embryos and fetus should be protected from infections, while the female dog must tolerate the growing of semi-allografts in her uterus. After birth, newborn puppies are at great risk of developing infectious diseases, because their immune system is in development and immune memory is absent. Passive transfer of immunity through colostrum is fundamental for puppy survival in the first weeks of life, but hampers the development of an active immune response to vaccination. At the end of life, dogs experience a decline in the structure and functional competence of the immune system, compromising the immune responses to novel antigenic challenges, such as infections and vaccines. Therefore, the current article reviews the general processes related to the development of the dog´s immune system, providing an overview of immune activity throughout the dog's life and its implications in canine health, and highlighting priority research goals.

Myocardial infarction triggers cardioprotective antigen-specific T helper cell responses

T cell autoreactivity is a hallmark of autoimmune diseases but can also benefit self-maintenance and foster tissue repair. Herein, we investigated whether heart-specific T cells exert salutary or detrimental effects in the context of myocardial infarction (MI), the leading cause of death worldwide. After screening more than 150 class-II-restricted epitopes, we found that myosin heavy chain alpha (MYHCA) was a dominant cardiac antigen triggering post-MI CD4+ T cell activation in mice. Transferred MYHCA614-629-specific CD4+ T (TCR-M) cells selectively accumulated in the myocardium and mediastinal lymph nodes (med-LN) of infarcted mice, acquired a Treg phenotype with a distinct pro-healing gene expression profile, and mediated cardioprotection. Myocardial Treg cells were also detected in autopsies from patients who suffered a MI. Noninvasive PET/CT imaging using a CXCR4 radioligand revealed enlarged med-LNs with increased cellularity in MI-patients. Notably, the med-LN alterations observed in MI patients correlated with the infarct size and cardiac function. Taken together, the results obtained in our study provide evidence showing that MI-context induces pro-healing T cell autoimmunity in mice and confirms the existence of an analogous heart/med-LN/T cell axis in MI patients.

Multi-color flow cytometry for evaluating age-related changes in memory lymphocyte subsets in dogs

While dogs are increasingly being utilized as large-animal models of disease, important features of age-related immunosenescence in the dog have yet to be evaluated due to the lack of defined naïve vs. memory T lymphocyte phenotypes. We therefore performed multi-color flow cytometry on peripheral blood mononuclear cells from young and aged beagles, and determined the differential cytokine production by proposed memory subsets. CD4+ and CD8+ T lymphocytes in aged dogs displayed increased cytokine production, and decreased proliferative capacity. Antibodies targeting CD45RA and CD62L, but less so CD28 or CD44, defined canine cells that consistently exhibited properties of naïve-, central memory-, effector memory-, and terminal effector-like CD4+ and CD8+ T lymphocyte subsets. Older dogs demonstrated decreased frequencies of naïve-like CD4+ and CD8+ T lymphocytes, and an increased frequency of terminal effector-like CD8+ T lymphocytes. Overall findings revealed that aged dogs displayed features of immunosenescence similar to those reported in other species.