DOS: Small Animal Studies

The research involving a small cyclif pentapeptide; DOS46L in mouse models demonstrated dramatic results in reversing immune senescence and restoring systemic health. These compounds dismantle sestrin-MAPK complexes in senescent T cells, rejuvenating them into long-lived, stem-like memory cells. In influenza-infected mice, DOS provided full protection against lethal infections by enhancing immune responses, generating virus-specific antibodies, and eliminating viral titers without vaccination. Markers of inflammation, such as IFN-γ and IL-10, were modulated, contributing to controlled immune responses and improved systemic health, including reduced weight loss and enhanced clinical scores during infection.

In the animal studies investigating the effects of DOS compounds on immune function, mice were challenged with the yellow fever vaccine to assess how these compounds could rejuvenate aged immune systems. In one study, vaccinated mice were treated with DOS and their T cells were exposed to yellow fever peptides preloaded on autologous antigen-presenting cells. DOS treatment led to a robust immune response, evidenced by increased production of IFN-γ, a crucial antiviral cytokine. Notably, the treated mice showed the generation of T stem-like cells (TSTEM), which exhibited enhanced proliferation and cytokine release when re-exposed to the yellow fever antigens. This response suggested that DOS compounds were not only rejuvenating the T cells but also enabling them to retain and expand their ability to respond to new infections.

In a parallel study using OT-II transgenic mice, which are genetically engineered to recognize only a specific antigen (ovalbumin), DOS treatment remarkably expanded the antigenic repertoire of these mice. Following treatment, the OT-II mice could mount a specific immune response against yellow fever antigens, demonstrating that DOS compounds extend the antigen-recognition capacity of aged or antigen-limited immune cells. These findings underscore DOS's potential to both reverse immune senescence and enhance immune protection against new viral challenges like yellow fever.

Although the studies primarily focused on immune function, there is broader evidence linking the modulation of inflammation with improved muscle strength and cognitive function, though these specific parameters were not directly measured in the DOS-treated mice. The long-term efficacy of a single DOS dose, which maintained immune protection for months, offers a promising avenue for treating age-related immune decline and possibly other systemic effects.

In the study “Rejuvenation Driven Reprogramming in T Lymphocytes,” systemic safety and therapeutic potential of DOS46L were rigorously evaluated in several mouse models. Here's a detailed summary of the findings:

1. Systemic Safety of DOS46L:

In the mouse studies, DOS46L was administered at doses of 0.1 mg/kg in old mice (aged 18 months) to evaluate both short- and long-term safety. The clinical scores, which included fur condition, posture, movement, breathing, and eye state, were monitored alongside body weight and disease progression over a 15-day period post-treatment. These comprehensive assessments were performed under veterinary supervision, ensuring that the animals’ overall health was well-maintained during the experiment​ .

The mice did not exhibit any adverse reactions following DOS46L administration, even at any tested concentration, demonstrating that DOS46L can be safely administered without toxic effects.  Additionally, long-term safety evaluations indicated no significant toxicity or signs of harm, as assessed by tissue analysis of organs like the lungs, spleen, and thymus, where no abnormalities or necrosis were observed .

2. Therapeutic Potential of DOS46L:

DOS46L demonstrated exceptional therapeutic potential, particularly in reversing immune senescence and enhancing immune responses in aged mice:

• Immune Rejuvenation: The treatment with DOS46L led to the rejuvenation of senescent T cells, promoting the formation of stem-like memory T cells. These rejuvenated cells showed improved antigen recognition and increased responsiveness to viral infections, such as H1N1.

• Influenza Protection: Mice treated with DOS46L were infected with a lethal dose of H1N1 flu virus six months after vaccination, and their survival was monitored. Notably, DOS46L-treated mice showed 100% survival, which was comparable to younger, vaccinated mice. In contrast, older mice that did not receive DOS46L had significantly lower survival rates. This demonstrated the compound's prophylactic potential to protect aged mice from lethal infections even without further vaccine boosting.

• Cytokine Modulation and Viral Clearance: The study also highlighted cytokine modulation as a key mechanism of action. Treated mice showed elevated levels of IFN-γ and IL-10, which are critical for viral clearance and controlling inflammation. Additionally, lung tissues of DOS46L-treated mice showed significantly lower viral loads, as quantified by qPCR, indicating efficient viral elimination.

• Vaccine Adjuvants and Cancer Immunotherpies: DOS could enhance both the durability and breadth of vaccine responses, helping the immune system to overcome age-related declines that typically weaken vaccine efficacy, especially in elderly or immunocompromised populations. This enhanced response has shown promise in experimental flu models, where DOS-treated immune cells provided superior protection against infections even without additional vaccination​​. Thus, DOS compounds have strong potential for improving outcomes in both prophylactic vaccines and cancer immunotherapies by harnessing and extending immune memory and responsiveness.

• Long-term Benefits: Importantly, DOS46L induced long-lasting benefits. A single injection of DOS46L at 0.1 mg/kg was sufficient to maintain immune rejuvenation and enhanced antibody production for at least 8 weeks post-treatment. Furthermore, DOS46L silenced sestrin expression and prevented immune exhaustion by promoting sustained checkpoint inhibitor downregulation (e.g., PD-1, TIM-3) on T cells, allowing them to remain active and effective.

• Stem-like Memory Cells: DOS46L's action promoted the conversion of exhausted T cells into stem-like memory cells, contributing to enhanced long-term immune memory and improved vaccine responses in aged mice.

Conclusion:

The systemic safety of DOS46L was confirmed in these small animal studies, with no observed toxicity even after long-term administration. Its therapeutic potential was evident in its ability to rejuvenate aged immune systems, offering protection from lethal infections and restoring immune function in older organisms. These findings suggest that DOS46L holds significant promise as both a prophylactic and therapeutic agent for treating age-related immune decline and enhancing vaccine efficacy in the elderly.

Reference:

[2024] Rejuvenation driven reprograming in T lymphocytes.pdf