Immunologic and dose dependent effects of rapamycin and its evolving role in chemoprevention

Autophagy: A Silent Protagonist in Kidney Transplantation

Autophagy is a lysosome-dependent regulated mechanism that recycles unnecessary cytoplasmic components. It is now known that autophagy dysfunction may have a pathogenic role in several human diseases and conditions, including kidney transplantation. Both defective and excessive autophagy may induce or aggravate several complications of kidney transplantation, such as ischemia-reperfusion injury, alloimmune response, and immunosuppressive treatment and side effects. Although it is still complicated to measure autophagy levels in clinical practice, more attention should be paid to the factors that may influence autophagy. In kidney transplantation, the association of low doses of a mammalian target of rapamycin inhibitor with low doses of a calcineurin inhibitor may be of benefit for autophagy modulation. However, further studies are needed to explore the role of other autophagy regulators.

mTOR signaling is required for phagocyte free radical production, GLUT1 expression, and control of Staphylococcus aureus infection

Mammalian target of rapamycin (mTOR) is a key regulator of metabolism in the mammalian cell. Here, we show the essential role for mTOR signaling in the immune response to bacterial infection. Inhibition of mTOR during infection with Staphylococcus aureus revealed that mTOR signaling is required for bactericidal free radical production by phagocytes. Mechanistically, mTOR supported glucose transporter GLUT1 expression, potentially through hypoxia-inducible factor 1α, upon phagocyte activation. Cytokine and chemokine signaling, inducible nitric oxide synthase, and p65 nuclear translocation were present at similar levels during mTOR suppression, suggesting an NF-κB-independent role for mTOR signaling in the immune response during bacterial infection. We propose that mTOR signaling primarily mediates the metabolic requirements necessary for phagocyte bactericidal free radical production. This study has important implications for the metabolic requirements of innate immune cells during bacterial infection as well as the clinical use of mTOR inhibitors.IMPORTANCESirolimus, everolimus, temsirolimus, and similar are a class of pharmaceutics commonly used in the clinical treatment of cancer and the anti-rejection of transplanted organs. Each of these agents suppresses the activity of the mammalian target of rapamycin (mTOR), a master regulator of metabolism in human cells. Activation of mTOR is also involved in the immune response to bacterial infection, and treatments that inhibit mTOR are associated with increased susceptibility to bacterial infections in the skin and soft tissue. Infections caused by Staphylococcus aureus are among the most common and severe. Our study shows that this susceptibility to S. aureus infection during mTOR suppression is due to an impaired function of phagocytic immune cells responsible for controlling bacterial infections. Specifically, we observed that mTOR activity is required for phagocytes to produce antimicrobial free radicals. These results have important implications for immune responses during clinical treatments and in disease states where mTOR is suppressed.

Enhancement efficiency delivery of antiviral Molnupiravir-drug via the loading with self-assembly nanoparticles of pycnogenol and cellulose which are decorated by zinc oxide nanoparticles for COVID-19 therapy

The target of the study is to modify the efficiency of Molnupiravir-drug (MOL) for COVID-19 therapy via the rearrangement of the building engineering of MOL-drug by loading it with self-assembly biomolecules nanoparticles (NPs) of pycnogenol (Pyc) and cellulose (CNC) which are decorated by zinc oxide nanoparticles. The synthesis and characterization of the modified drug are performing successfully, the loading and release process of the MOL drug on a nano surface is measured by UV-Vis spectroscopy under room temperature and different pH. The release efficiency of the MOL drug is calculated to be 65% (pH 6.8) and 69% (pH 7.4). The modified MOL drug displays 71% (pH 6.8) and 78% (pH 7.4) for CNC@Pyc.MOL nanocomposite, while CNC@Pyc.MOL.ZnO nanocomposite gave values at 76% (pH 6.8) and 78% (pH 7.4), the efficiency recorded after 19 h. The biological activity of the MOL-drug and modified MOL-drug is measured, and the cytotoxicity is performed by SRB technique, where the self-assembly (CNC@Pyc) appears to be a safe healthy, and high viability against the examined cell line. The antioxidant activity and anti-inflammatory are evaluated, where the nanocomposite that has ZnO NPs (CNC@Pyc.MOL.ZnO) gave high efficiency compared to the composite without ZnO NPs. The CPE-inhibition assay is used to identify potential antivirals against CVID-19 (229E virus), the viral inhibition (%) was reported at 37.6 % (for 800 µg/ml) and 18.02 % (for 400 µg/ml) of CNC@Pyc.MOL.ZnO. So, the modified MOL-drug was suggested as a replacement drug for the therapy of COVID-19 compared to MOL-drug, but the results need clinical trials.

Environment relevant exposure of perfluorooctanoic acid accelerates the growth of hepatocellular carcinoma cells through mammalian target of rapamycin (mTOR) signal pathway

Perfluorooctanoic acid (PFOA), a synthetic alkyl chain fluorinated compound, has emerged as a persistent organic pollutant of grave concern, casting a shadow over both ecological integrity and humans. Its insidious presence raises alarms due to its capacity to bioaccumulate within the human liver, potentially paving the treacherous path toward liver cancer. Yet, the intricate mechanisms underpinning PFOA's role in promoting the growth of hepatocellular carcinoma (HCC) remain shrouded in ambiguity. Here, we determined the proliferation and transcription changes of HCC after PFOA exposure through integrated experiments including cell culture, nude mice tests, and colony-forming assays. Based on our findings, PFOA effectively promotes the proliferation of HCC cells within the experimental range of concentrations, both in vivo and in vitro. The proliferation efficiency of HCC cells was observed to increase by approximately 10% due to overexposure to PFOA. Additionally, the cancer weight of tumor-bearing nude mice increased by 87.0% (p < 0.05). We systematically evaluated the effects of PFOA on HCC cells and found that PFOA's exposure can selectively activate the PI3K/AKT/mTOR/4E-BP1 signaling pathway, thereby playing a pro-cancer effect on HCC cells Confirmation echoed through western blot assays and inhibitor combination analyses. These insights summon a response to PFOA's dual nature as both an environmental threat and a promoter of liver cancer. Our work illuminates the obscured domain of PFOA-induced hepatoxicity, shedding light on its ties to hepatocellular carcinoma progression.

Infectious complications of vascular anomalies treated with sirolimus: A systematic review

BACKGROUND AND OBJECTIVES

Initially developed as immunosuppressive agents, mammalian target of rapamycin (mTOR) inhibitors are currently used widely in the management of vascular malformations and tumors. The incidence of infectious complications in the vascular anomalies (VA) population is not well defined. The goal of this systematic review was to better define the types and severity of reported infectious complications in patients with VAs treated with mTOR inhibition.

METHODS

This was a systematic review conducted following PRISMA guidelines evaluating all research articles focused on infectious complications in patients with VAs treated with sirolimus or everolimus. Thirty articles including 1182 total patients and 316 infections (in 291 unique patients) were ultimately included.

RESULTS

The majority of infections were viral upper respiratory (n = 137, 54%), followed by pneumonia (n = 53, 20%), and cutaneous infections (n = 20, 8%). There were six total infection-related fatalities, which all occurred in patients younger than 2 years. Two cases of Pneumocystis jirovecii pneumonia (PJP) were reported. These were infants with kaposiform hemangioendothelioma (KHE) who were also treated with steroids and did not receive PJP prophylaxis. Almost one-third (n = 96, 32%) of infectious complications were graded 3-4 according to Common Terminology Criteria for Adverse Events (CTCAE) criteria. Details of patient age, subtype of VA, and timing of infection were lacking from many reports.

CONCLUSIONS

Most infectious complications reported in patients with VA on mTOR inhibitors were viral respiratory infections and non-severe. Bacteremia, infectious fatalities, and PJP are exceedingly rare. Future studies are needed to clarify the spectrum of infectious risks in VA patients and to provide guidance for infection prevention.

Temsirolimus is a promising immunomodulatory agent for enhanced transplantation outcomes

BACKGROUND

Identifying effective immunosuppressive strategies is critical for addressing immunological rejection following organ transplantation. This study explores the potential immunosuppressive effects and mechanisms of temsirolimus, a rapamycin derivative, in organ transplantation.

METHODS

A mouse cardiac allograft model was established using a cervical cannula technique with BALB/c donors and C57BL/6 recipients. Mice were administered temsirolimus intragastrically and graft survival was evaluated. Histological staining was used to assess pathological changes. The BrdU assay was used to measure splenic T cell proliferation. Flow cytometry was used to quantify regulatory T cells (Tregs), CD4+ T cells, and CD8+ T cells. ELISA and qPCR assays were used to determine Foxp3, IL-4, IFN-γ, and TGF-β expression.

RESULTS

Temsirolimus displayed potent immunosuppressive effects at 20 mg/kg/day, significantly inhibiting T cell proliferation (84.6%, P < 0.0001) and prolonging graft survival (median 49 days vs. 8.5 days in controls, P < 0.0001). However, median survival decreased to 34.5 days upon withdrawal. Temsirolimus also reduced splenic CD4+ and CD8+ T cells (2.85% and 2.92%, P < 0.001) and antibody levels (IgM, IgG1, IgG2) by 11.85-29.09% (P < 0.0001) and increased Tregs, Foxp3, IL-4 (P < 0.01), and TGF-β (P < 0.05), while decreasing IFN-γ (P < 0.001).

CONCLUSIONS

Temsirolimus exhibited potent immunosuppressive effects, emerging as a strong candidate to mitigate organ transplant rejection.

Effect of rapamycin on Cryptococcus neoformans: cellular organization, biophysics and virulence factors

Background: Cryptococcus neoformans is an opportunistic fungal pathogen that causes infections mainly in immunosuppressed individuals, such as transplant recipients. Aims: This study investigated the effects of rapamycin, an immunosuppressant drug, on the cellular organization, biophysical characteristics, and main virulence factors of C. neoformans. Methods: Morphological, structural, physicochemical and biophysical analyses of cells and secreted polysaccharides of the reference H99 C. neoformans strain were investigated under the effect of subinhibitory concentrations of rapamycin. Results: Rapamycin at a minimum inhibitory concentration of 2.5 μM reduced C. neoformans cell viability by 53%, decreased capsule, increased cell size, chitin and lipid body formation, and changed peptidase and urease activity. Conclusion: Further studies are needed to assess how rapamycin affects the virulence factors and pathogenicity of C. neoformans.

Dual-locus, dual-HDR editing permits efficient generation of antigen-specific regulatory T cells with robust suppressive activity

Adoptive regulatory T (Treg) cell therapy is predicted to modulate immune tolerance in autoimmune diseases, including type 1 diabetes (T1D). However, the requirement for antigen (ag) specificity to optimally orchestrate tissue-specific, Treg cell-mediated tolerance limits effective clinical application. To address this challenge, we present a single-step, combinatorial gene editing strategy utilizing dual-locus, dual-homology-directed repair (HDR) to generate and specifically expand ag-specific engineered Treg (EngTreg) cells derived from donor CD4+ T cells. Concurrent delivery of CRISPR nucleases and recombinant (r)AAV homology donor templates targeting FOXP3 and TRAC was used to achieve three parallel goals: enforced, stable expression of FOXP3; replacement of the endogenous T cell receptor (TCR) with an islet-specific TCR; and selective enrichment of dual-edited cells. Each HDR donor template contained an alternative component of a heterodimeric chemically inducible signaling complex (CISC), designed to activate interleukin-2 (IL-2) signaling in response to rapamycin, promoting expansion of only dual-edited EngTreg cells. Using this approach, we generated purified, islet-specific EngTreg cells that mediated robust direct and bystander suppression of effector T (Teff) cells recognizing the same or a different islet antigen peptide, respectively. This platform is broadly adaptable for use with alternative TCRs or other targeting moieties for application in tissue-specific autoimmune or inflammatory diseases.

Randomized, double-blind, placebo-controlled trial of rapamycin in amyotrophic lateral sclerosis

In preclinical studies rapamycin was found to target neuroinflammation, by expanding regulatory T cells, and affecting autophagy, two pillars of amyotrophic lateral sclerosis (ALS) pathogenesis. Herein we report a multicenter, randomized, double-blind trial, in 63 ALS patients who were randomly assigned in a 1:1:1 ratio to receive rapamycin 2 mg/m2/day,1 mg/m2/day or placebo (EUDRACT 2016-002399-28; NCT03359538). The primary outcome, the number of patients exhibiting an increase >30% in regulatory T cells from baseline to treatment end, was not attained. Secondary outcomes were changes from baseline of T, B, NK cell subpopulations, inflammasome mRNA expression and activation status, S6-ribosomal protein phosphorylation, neurofilaments; clinical outcome measures of disease progression; survival; safety and quality of life. Of the secondary outcomes, rapamycin decreased mRNA relative expression of the pro-inflammatory cytokine IL-18, reduced plasmatic IL-18 protein, and increased the percentage of classical monocytes and memory switched B cells, although no corrections were applied for multiple tests. In conclusion, we show that rapamycin treatment is well tolerated and provides reassuring safety findings in ALS patients, but further trials are necessary to understand the biological and clinical effects of this drug in ALS.