Lovastatin inhibits T-cell proliferation while preserving the cytolytic function of EBV, CMV, and MART-1-specific CTLs

Cholesterol induction in CD8+ T cell exhaustion in colorectal cancer via the regulation of endoplasmic reticulum-mitochondria contact sites

BACKGROUND

Hypercholesterolemia is one of the risk factors for colorectal cancer (CRC). Cholesterol can participate in the regulation of human T cell function and affect the occurrence and development of CRC.

OBJECTIVE

To elucidate the pathogenesis of CRC immune escape mediated by CD8+ T cell exhaustion induced by cholesterol.

METHODS

CRC samples (n = 217) and healthy individuals (n = 98) were recruited to analyze the relationship between peripheral blood cholesterol levels and the clinical features of CRC. An animal model of CRC with hypercholesterolemia was established. Intraperitoneal intervention with endoplasmic reticulum stress (ERS) inhibitors in hypercholesterolemic CRC mice was performed. CD69, PD1, TIM-3, and CTLA-4 on CD8+ T cells of spleens from C57BL/6 J mice were detected by flow cytometry. CD8+ T cells were cocultured with MC38 cells (mouse colon cancer cell line). The proliferation, apoptosis, migration and invasive ability of MC38 cells were detected by CCK-8 assay, Annexin-V APC/7-AAD double staining, scratch assay and transwell assay, respectively. Transmission electron microscopy was used to observe the ER structure of CD8+ T cells. Western blotting was used to detect the expression of ERS and mitophagy-related proteins. Mitochondrial function and energy metabolism were measured. Immunoprecipitation was used to detect the interaction of endoplasmic reticulum-mitochondria contact site (ERMC) proteins. Immunofluorescence colocalization was used to detect the expression and intracellular localization of ERMC-related molecules.

RESULTS

Peripheral blood cholesterol-related indices, including Tc, low density lipoproteins (LDL) and Apo(a), were all increased, and high density lipoprotein (HDL) was decreased in CRCs. The proliferation, migration and invasion abilities of MC38 cells were enhanced, and the proportion of tumor cell apoptosis was decreased in the high cholesterol group. The expression of IL-2 and TNF-α was decreased, while IFN-γ was increased in the high cholesterol group. It indicated high cholesterol could induce exhaustion of CD8+ T cells, leading to CRC immune escape. Hypercholesterolemia damaged the ER structure of CD8+ T cells and increased the expression of ER stress molecules (CHOP and GRP78), lead to CD8+ T cell exhaustion. The expression of mitophagy-related proteins (BNIP3, PINK and Parkin) in exhausted CD8+ T cells increased at high cholesterol levels, causing mitochondrial energy disturbance. High cholesterol enhanced the colocalization of Fis1/Bap31, MFN2/cox4/HSP90B1, VAPB/PTPIP51, VDAC1/IPR3/GRP75 in ERMCs, indicated that high cholesterol promoted the intermolecular interaction between ER and mitochondrial membranes in CD8+ T cells.

CONCLUSION

High cholesterol regulated the ERS-ERMC-mitophagy axis to induce the exhaustion of CD8+ T cells in CRC.

Inhibitors of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase (Statins) Suppress Proliferation and Motility of Human CD4+ T Lymphocytes in Culture

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) along with their blood lipid-lowering effect exhibit anti-inflammatory and immunomodulatory activity. We studied the effects of long-term (72-h or longer) exposure of human T lymphocytes in culture to atorvastatin and rosuvastatin (5-80 nM) on their functional activity. Treatment with statins inhibited PHA/IL-2-induced proliferation of CD4⁺ T lymphocytes isolated from the peripheral blood of healthy donors. This was accompanied by a decrease in the relative content of cells expressing active caspase-3. Addition of mevalonate or fetal bovine serum simultaneously with statins restored proliferative activity of cells. Culturing of CD4⁺ T lymphocytes with statins in the presence of IL-2 did not significantly affect the expression of chemokine receptors CCR4, CCR5, CXCR3, and CXCR4. Pretreatment with statins suppressed spontaneous and SDF-1-stimulated migration of CD4⁺ T lymphocytes, but little changed the content of intracellular phosphorylated protein kinases Akt, p38 and p42/44 (ERK1/2). The cellular effects of "lipophilic" atorvastatin were observed at lower concentrations compared to "hydrophilic" rosuvastatin.

The Binary Model of Chronic Diseases Applied to COVID-19

A binary model for the classification of chronic diseases has formerly been proposed. The model classifies chronic diseases as “high Treg” or “low Treg” diseases according to the extent of regulatory T cells (Treg) activity (frequency or function) observed. The present paper applies this model to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The model correctly predicts the efficacy or inefficacy of several immune-modulating drugs in the treatment of severe coronavirus disease 2019 (COVID-19) disease. It also correctly predicts the class of pathogens mostly associated with SARS-CoV-2 infection. The clinical implications are the following: (a) any search for new immune-modulating drugs for the treatment of COVID-19 should exclude candidates that do not induce “high Treg” immune reaction or those that do not spare CD8+ T cells; (b) immune-modulating drugs, which are effective against SARS-CoV-2, may not be effective against any variant of the virus that does not induce “low Treg” reaction; (c) any immune-modulating drug, which is effective in treating COVID-19, will also alleviate most coinfections; and (d) severe COVID-19 patients should avoid contact with carriers of “low Treg” pathogens.

RORα Regulates Cholesterol Metabolism of CD8+ T Cells for Anticancer Immunity

Retinoic acid-related orphan receptor α (RORα) functions as a transcription factor for various biological processes, including circadian rhythm, inflammation, cancer, and lipid metabolism. Here, we demonstrate that RORα is crucial for maintaining cholesterol homeostasis in CD8⁺ T cells by attenuating NF-κB transcriptional activity. Cholesterol sulfate, the established natural agonist of RORα, exhibits cellular cytotoxicity on, and increased effector responses in, CD8⁺ T cells. Transcript analysis reveals that the suppression of RORα leads to the upregulation of NF-κB target genes in T cells. Chromatin immunoprecipitation analysis was used to determine the corecruitment of RORα and histone deacetylase (HDAC) on NF-κB target promoters and the subsequent dismissal of coactivators for transcriptional repression. We demonstrate that RORα/HDAC-mediated attenuation of NF-κB signaling controls the balance of cholesterol metabolism in CD8⁺ T cells, and that therapeutic strategies targeting this epigenetic regulation could be beneficial to the treatment of solid tumors including colon cancers.

Verification of the effects of calcium channel blockers on the immune microenvironment of breast cancer

BACKGROUND

A higher density of tumor-infiltrating lymphocytes (TILs) can lead to greater therapeutic effects and improved prognoses in cancer treatment. Similar results have been observed in breast cancer, particularly in triple-negative breast cancer (TNBC) and human epidermal growth factor receptor 2-enriched breast cancer. Calcium channel blockers (CCBs) are antihypertensive drugs (AHTs) that have also been reported to suppress the functions of T cells and macrophages. In this study, we evaluated TILs before pre-operative chemotherapy (POC) in breast cancer and retrospectively analyzed the correlation between CCBs and TILs or prognosis.

METHODS

Of the patients treated with POC, 338 who had evaluable TILs were enrolled in this study. The correlations among TILs were evaluated according to standard methods, and CCB use and prognosis were investigated retrospectively.

RESULTS

Before POC, 65 patients (19.2%) took AHTs (CCBs: 41/338, 12.1%). The TIL density was significantly lower among patients administered CCBs for the group of all patients and for patients with TNBC (p = 0.040, p = 0.009, respectively). Additionally, patients with TNBC who were administered CCBs showed significantly lower response rates for POC (p = 0.040). In all patients receiving POC, no significant differences in disease-free survival (DFS) or overall survival (OS) were observed in patients administered CCBs (p = 0.712, p = 0.478, log-rank tests, respectively). Furthermore, no significant differences were found, even in patients with TNBC (DFS: p = 0.441, OS: p = 0.727, log-rank tests, respectively).

CONCLUSIONS

In patients with TNBC undergoing treatment for hypertension with CCBs, TILs in the needle biopsy specimens before treatment were significantly lower, and the response rate of POC was not sufficient. Thus, the immunosuppressive effects of CCBs may also affect the immune microenvironment.

Cellular Cholesterol Facilitates the Postentry Replication Cycle of Herpes Simplex Virus 1

Cholesterol is an essential component of cell membranes and is required for herpes simplex virus 1 (HSV-1) entry (1-3). Treatment of HSV-1-infected Vero cells with methyl beta-cyclodextrin from 2 to 9 h postentry reduced plaque numbers. Transport of incoming viral capsids to the nuclear periphery was unaffected by the cholesterol reduction, suggesting that cell cholesterol is important for the HSV-1 replicative cycle at a stage(s) beyond entry, after the arrival of capsids at the nucleus. The synthesis and release of infectious HSV-1 and cell-to-cell spread of infection were all impaired in cholesterol-reduced cells. Propagation of HSV-1 on DHCR24^-/- fibroblasts, which lack the desmosterol-to-cholesterol conversion enzyme, resulted in the generation of infectious extracellular virions (HSV^des) that lack cholesterol and likely contain desmosterol. The specific infectivities (PFU per viral genome) of HSV^chol and HSV^des were similar, suggesting cholesterol and desmosterol in the HSV envelope support similar levels of infectivity. However, infected DHCR24^-/- fibroblasts released ∼1 log less infectious HSV^des and ∼1.5 log fewer particles than release of cholesterol-containing particles (HSV^chol) from parental fibroblasts, suggesting that the hydrocarbon tail of cholesterol facilitates viral synthesis. Together, the results suggest multiple roles for cholesterol in the HSV-1 replicative cycle.IMPORTANCE HSV-1 infections are associated with a wide range of clinical manifestations that are of public health importance. Cholesterol is a key player in the complex interaction between viral and cellular factors that allows HSV-1 to enter host cells and establish infection. Previous reports have demonstrated a role for cellular cholesterol in the entry of HSV-1 into target cells. Here, we employed both chemical treatment and cells that were genetically defined to synthesize only desmosterol to demonstrate that cholesterol is important at stages following the initial entry and transport of viral capsids to the nucleus. Viral protein expression, encapsidation of the viral genome, and the release of mature virions were impacted by the reduction of cellular cholesterol. Cholesterol was also critical for cell-to-cell spread of infection. These findings provide new insights into the cholesterol dependence of HSV-1 replication.

Complement component C3 mediates Th1/Th17 polarization in human T-cell activation and cutaneous GVHD

The complement system has been shown to regulate T-cell activation and alloimmune responses in GVHD. Mice deficient in the central component of complement system C3 have significantly lower GVHD-related mortality/morbidity, and C3 modulates Th1/Th17 polarization in mouse GVHD. To investigate whether anticomplement therapy has any impact on human T-cell activation, a drug candidate Compstatin was used to inhibit C3 activation in this study. We found the frequency of IFN-γ (Th1)-, IL-4 (Th2)-, IL-17 (Th17)-, IL-2- and TNF-α-producing cells were significantly reduced among activated CD4(+) cells in the presence of Compstatin. Compstatin treatment decreased the proliferation of both CD4(+) and CD8(+) T cells upon TCR stimulation. However, Compstatin does not affect the production of IL-2 and TNF-α in activated CD8(+) T cells, and the differentiation of CD8(+) T cells into distinct memory and effector subsets remained intact. Furthermore, we examined complement deposition in skin and lip biopsy samples of patients diagnosed with cutaneous GVHD. C3 deposition was detected in the squamous epithelium and dermis, blood vessels and damaged sweat glands, and was associated with gland damage and regeneration. We conclude that C3 mediates Th1/Th17 polarization in human T-cell activation and skin GVHD in patients.

Immunosuppressive decalin derivatives from red yeast rice

Five new decalin derivatives (1-5), together with two known compounds (6 and 7), were isolated from the ethyl acetate extract of red yeast rice. Their structures were elucidated by means of NMR and mass spectroscopic analyses. Monascusic lactone A (1) is the first reported naturally occurring decalin derivative possessing a spiro lactone at the C-1 position. The immunosuppressive effects of all these isolates (1-7) on human T cell proliferation were investigated, and all, especially monascusic acids B (2), C (3), D (4), and A (6) and heptaketide (7), suppressed human T cell proliferation in a dose-dependent manner from 10 to 100 μM. This is the first report on the immunosuppressive activity of decalin derivatives.