Efficacy of tomato concentrates in mouse models of dyslipidemia and cancer

ApoA-I mimetics reduce systemic and gut inflammation in chronic treated HIV

Novel therapeutic strategies are needed to attenuate increased systemic and gut inflammation that contribute to morbidity and mortality in chronic HIV infection despite potent antiretroviral therapy (ART). The goal of this study is to use preclinical models of chronic treated HIV to determine whether the antioxidant and anti-inflammatory apoA-I mimetic peptides 6F and 4F attenuate systemic and gut inflammation in chronic HIV. We used two humanized murine models of HIV infection and gut explants from 10 uninfected and 10 HIV infected persons on potent ART, to determine the in vivo and ex vivo impact of apoA-I mimetics on systemic and intestinal inflammation in HIV. When compared to HIV infected humanized mice treated with ART alone, mice on oral apoA-I mimetic peptide 6F with ART had consistently reduced plasma and gut tissue cytokines (TNF-α, IL-6) and chemokines (CX3CL1) that are products of ADAM17 sheddase activity. Oral 6F attenuated gut protein levels of ADAM17 that were increased in HIV-1 infected mice on potent ART compared to uninfected mice. Adding oxidized lipoproteins and endotoxin (LPS) ex vivo to gut explants from HIV infected persons increased levels of ADAM17 in myeloid and intestinal cells, which increased TNF-α and CX3CL1. Both 4F and 6F attenuated these changes. Our preclinical data suggest that apoA-I mimetic peptides provide a novel therapeutic strategy that can target increased protein levels of ADAM17 and its sheddase activity that contribute to intestinal and systemic inflammation in treated HIV. The large repertoire of inflammatory mediators involved in ADAM17 sheddase activity places it as a pivotal orchestrator of several inflammatory pathways associated with morbidity in chronic treated HIV that make it an attractive therapeutic target.

Oxidized phospholipids cause changes in jejunum mucus that induce dysbiosis and systemic inflammation

We previously reported that adding a concentrate of transgenic tomatoes expressing the apoA-I mimetic peptide 6F (Tg6F) to a Western diet (WD) ameliorated systemic inflammation. To determine the mechanism(s) responsible for these observations, Ldlr-/- mice were fed chow, a WD, or WD plus Tg6F. We found that a WD altered the taxonomic composition of bacteria in jejunum mucus. For example, Akkermansia muciniphila virtually disappeared, while overall bacteria numbers and lipopolysaccharide (LPS) levels increased. In addition, gut permeability increased, as did the content of reactive oxygen species and oxidized phospholipids in jejunum mucus in WD-fed mice. Moreover, gene expression in the jejunum decreased for multiple peptides and proteins that are secreted into the mucous layer of the jejunum that act to limit bacteria numbers and their interaction with enterocytes including regenerating islet-derived proteins, defensins, mucin 2, surfactant A, and apoA-I. Following WD, gene expression also decreased for Il36γ, Il23, and Il22, cytokines critical for antimicrobial activity. WD decreased expression of both Atoh1 and Gfi1, genes required for the formation of goblet and Paneth cells, and immunohistochemistry revealed decreased numbers of goblet and Paneth cells. Adding Tg6F ameliorated these WD-mediated changes. Adding oxidized phospholipids ex vivo to the jejunum from mice fed a chow diet reproduced the changes in gene expression in vivo that occurred when the mice were fed WD and were prevented with addition of 6F peptide. We conclude that Tg6F ameliorates the WD-mediated increase in oxidized phospholipids that cause changes in jejunum mucus, which induce dysbiosis and systemic inflammation.

The ApoA-I mimetic peptide 4F attenuates in vitro replication of SARS-CoV-2, associated apoptosis, oxidative stress and inflammation in epithelial cells

An oral antiviral against SARS-CoV-2 that also attenuates inflammatory instigators of severe COVID-19 is not available to date. Herein, we show that the apoA-I mimetic peptide 4 F inhibits Spike mediated viral entry and has antiviral activity against SARS-CoV-2 in human lung epithelial Calu3 and Vero-E6 cells. In SARS-CoV-2 infected Calu3 cells, 4 F upregulated inducers of the interferon pathway such as MX-1 and Heme oxygenase 1 (HO-1) and downregulated mitochondrial reactive oxygen species (mito-ROS) and CD147, a host protein that mediates viral entry. 4 F also reduced associated cellular apoptosis and secretion of IL-6 in both SARS-CoV-2 infected Vero-E6 and Calu3 cells. Thus, 4 F attenuates in vitro SARS-CoV-2 replication, associated apoptosis in epithelial cells and secretion of IL-6, a major cytokine related to COVID-19 morbidity. Given established safety of 4 F in humans, clinical studies are warranted to establish 4 F as therapy for COVID-19.

Apolipoprotein A-I mimetics attenuate macrophage activation in chronic treated HIV

OBJECTIVES

Despite antiretroviral therapy (ART), there is an unmet need for therapies to mitigate immune activation in HIV infection. The goal of this study is to determine whether the apoA-I mimetics 6F and 4F attenuate macrophage activation in chronic HIV.

DESIGN

Preclinical assessment of the in-vivo impact of Tg6F and the ex-vivo impact of apoA-I mimetics on biomarkers of immune activation and gut barrier dysfunction in treated HIV.

METHODS

We used two humanized murine models of HIV infection to determine the impact of oral Tg6F with ART (HIV+ART+Tg6F+) on innate immune activation (plasma human sCD14, sCD163) and gut barrier dysfunction [murine I-FABP, endotoxin (LPS), LPS-binding protein (LBP), murine sCD14]. We also used gut explants from 10 uninfected and 10 HIV-infected men on potent ART and no morbidity, to determine the impact of ex-vivo treatment with 4F for 72 h on secretion of sCD14, sCD163, and I-FABP from gut explants.

RESULTS

When compared with mice treated with ART alone (HIV+ART+), HIV+ART+Tg6F+ mice attenuated macrophage activation (h-sCD14, h-sCD163), gut barrier dysfunction (m-IFABP, LPS, LBP, and m-sCD14), plasma and gut tissue oxidized lipoproteins. The results were consistent with independent mouse models and ART regimens. Both 4F and 6F attenuated shedding of I-FABP and sCD14 from gut explants from HIV-infected and uninfected participants.

CONCLUSION

Given that gut barrier dysfunction and macrophage activation are contributors to comorbidities like cardiovascular disease in HIV, apoA-I mimetics should be tested as therapy for morbidity in chronic treated HIV.

Apolipoprotein mimetics in cancer

Peptides have many advantages over traditional therapeutics, including small molecules and other biologics, because of their low toxicity and immunogenicity, while still exhibiting efficacy. This review discusses the benefits and mechanism of action of apolipoprotein mimetic peptides in tumor biology and their potential utility in treating various cancers. Among lipoproteins in the circulation, high-density lipoprotein (HDL) and its constituents including apolipoprotein A-I (apoA-I; the predominant protein in HDL), apoJ, and apoE, harbor anti-tumorigenic activities. Peptides that mimic apoA-I function have been developed through molecular mimicry of the amphipathic α-helices of apoA-I. Oral apoA-I mimetic peptides remodel HDL, promote cholesterol efflux, sequester oxidized lipids, and activate anti-inflammatory processes. ApoA-I and apoJ mimetic peptides ameliorate various metrics of cancer progression and have demonstrated efficacy in preclinical models in the inhibition of ovarian, colon, breast, and metastatic lung cancers. Apolipoprotein mimetic peptides are poorly absorbed when administered orally and rapidly degraded when injected into the circulation. The small intestine is the major site of action for apoA-I mimetic peptides and recent studies suggest that modulation of immune cells in the lamina propria of the small intestine is, in part, a potential mechanism of action. Finally, several recent studies underscore the use of reconstituted HDL as target-specific nanoparticles carrying poorly soluble or unstable therapeutics to tumors even across the blood-brain barrier. Preclinical studies suggest that these versatile recombinant lipoprotein based nanoparticles and apolipoprotein mimetics can serve as safe, novel drug delivery, and therapeutic agents for the treatment of a number of cancers.

Oral 15-Hydroxyeicosatetraenoic Acid Induces Pulmonary Hypertension in Mice by Triggering T Cell-Dependent Endothelial Cell Apoptosis

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by increased mean pulmonary arterial pressure. Elevated plasma and lung concentrations of oxidized lipids, including 15-hydroxyeicosatetraenoic acid (15-HETE), have been demonstrated in patients with PAH and animal models. We previously demonstrated that feeding mice with 15-HETE is sufficient to induce pulmonary hypertension, but the mechanisms remain unknown. RNA sequencing data from the mouse lungs on 15-HETE diet revealed significant activation of pathways involved in both antigen processing and presentation and T cell-mediated cytotoxicity. Analysis of human microarray from patients with PAH also identified activation of identical pathways compared with controls. We show that in both 15-HETE-fed mice and patients with PAH, expression of the immunoproteasome subunit 5 is significantly increased, which was concomitant with an increase in the number of CD8/CD69 (cluster of differentiation 8 / cluster of differentiation 69) double-positive cells, as well as pulmonary arterial endothelial cell apoptosis in mice. Human pulmonary arterial endothelial cells cultured with 15-HETE were more prone to apoptosis when exposed to CD8 cells. Cultured intestinal epithelial cells secreted more oxidized lipids in response to 15-HETE, which is consistent with accumulation of circulating oxidized lipids in 15-HETE-fed mice. Administration of an apoA-I (apolipoprotein A-I) mimetic peptide, Tg6F (transgenic 6F), which is known to prevent accumulation of circulating oxidized lipids, not only inhibited pulmonary arterial endothelial cell apoptosis but also prevented and rescued 15-HETE-induced pulmonary hypertension in mice. In conclusion, our results suggest that (1) 15-HETE diet induces pulmonary hypertension by a mechanism that involves oxidized lipid-mediated T cell-dependent pulmonary arterial endothelial cell apoptosis and (2) Tg6F administration may be a novel therapy for treating PAH.

The role of the small intestine in modulating metabolism and inflammation in atherosclerosis and cancer

PURPOSE OF REVIEW

To discuss recent findings on the importance of the small intestine in modulating metabolism and inflammation in atherosclerosis and cancer.

RECENT FINDINGS

Integrin β7 natural gut intraepithelial T cells modulated metabolism and accelerated atherosclerosis in mice. Reducing the generation of lysophospholipids in the small intestine mimicked bariatric surgery and improved diabetes. Enterocyte-specific knockdown of stearoyl-CoA desaturase-1 significantly improved dyslipidemia in LDL receptor null (Ldlr) mice fed a Western diet. Adding a concentrate of tomatoes transgenic for the apolipoprotein A-I mimetic peptide 6F to the chow of wild-type mice altered lipid metabolism in the small intestine, preserved Notch signaling and reduced tumor burden in mouse models. The phospholipid-remodeling enzyme Lpcat3 regulated intestinal stem cells and progenitor cells by stimulating cholesterol biosynthesis; increasing cholesterol in the diet or through genetic manipulation promoted tumorigenesis in Apc mice.

SUMMARY

The small intestine is important for regulating metabolism and inflammation in animal models of both atherosclerosis and cancer.

A Novel HDL-Mimetic Peptide HM-10/10 Protects RPE and Photoreceptors in Murine Models of Retinal Degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness in the developed world. The retinal pigment epithelium (RPE) is a critical site of pathology in AMD. Oxidative stress plays a key role in the development of AMD. We generated a chimeric high-density lipoprotein (HDL), mimetic peptide named HM-10/10, with anti-oxidant properties and investigated its potential for the treatment of retinal disease using cell culture and animal models of RPE and photoreceptor (PR) degeneration. Treatment with HM-10/10 peptide prevented human fetal RPE cell death caused by tert-Butyl hydroperoxide (tBH)-induced oxidative stress and sodium iodate (NaIO₃), which causes RPE atrophy and is a model of geographic atrophy in mice. We also show that HM-10/10 peptide ameliorated photoreceptor cell death and significantly improved retinal function in a mouse model of N-methyl-N-nitrosourea (MNU)-induced PR degeneration. Our results demonstrate that HM-10/10 protects RPE and retina from oxidant injury and can serve as a potential therapeutic agent for the treatment of retinal degeneration.

Apolipoprotein A-I (ApoA-I), Immunity, Inflammation and Cancer

Apolipoprotein A-I (ApoA-I), the major protein component of high-density lipoproteins (HDL) is a multifunctional protein, involved in cholesterol traffic and inflammatory and immune response regulation. Many studies revealing alterations of ApoA-I during the development and progression of various types of cancer suggest that serum ApoA-I levels may represent a useful biomarker contributing to better estimation of cancer risk, early cancer diagnosis, follow up, and prognosis stratification of cancer patients. In addition, recent in vitro and animal studies disclose a more direct, tumor suppressive role of ApoA-I in cancer pathogenesis, which involves anti-inflammatory and immune-modulatory mechanisms. Herein, we review recent epidemiologic, clinicopathologic, and mechanistic studies investigating the role of ApoA-I in cancer biology, which suggest that enhancing the tumor suppressive activity of ApoA-I may contribute to better cancer prevention and treatment.

Apolipoprotein A-I mimetics mitigate intestinal inflammation in COX2-dependent inflammatory bowel disease model

Cyclooxygenase 2 (Cox2) total knockout and myeloid knockout (MKO) mice develop Crohn's-like intestinal inflammation when fed cholate-containing high fat diet (CCHF). We demonstrated that CCHF impaired intestinal barrier function and increased translocation of endotoxin, initiating TLR/MyD88-dependent inflammation in Cox2 KO but not WT mice. Cox2 MKO increased pro-inflammatory mediators in LPS-activated macrophages, and in the intestinal tissue and plasma upon CCHF challenge. Cox2 MKO also reduced inflammation resolving lipoxin A4 (LXA4) in intestinal tissue, while administration of an LXA4 analog rescued disease in Cox2 MKO mice fed CCHF. The apolipoprotein A-I (APOA1) mimetic 4F mitigated disease in both the Cox2 MKO/CCHF and piroxicam-accelerated Il10-/- models of inflammatory bowel disease (IBD) and reduced elevated levels of pro-inflammatory mediators in tissue and plasma. APOA1 mimetic Tg6F therapy was also effective in reducing intestinal inflammation in the Cox2 MKO/CCHF model. We further demonstrated that APOA1 mimetic peptides: i) inhibited LPS and oxidized 1-palmitoyl-2-arachidonoyl-sn-phosphatidylcholine (oxPAPC) dependent pro-inflammatory responses in human macrophages and intestinal epithelium; and ii) directly cleared pro-inflammatory lipids from mouse intestinal tissue and plasma. Our results support a causal role for pro-inflammatory and inflammation resolving lipids in IBD pathology and a translational potential for APOA1 mimetic peptides for the treatment of IBD.

Role of enterocyte stearoyl-Co-A desaturase-1 in LDLR-null mice

After crossing floxed stearoyl-CoA desaturase-1 (Scd1 ^fl/fl) mice with LDL receptor-null (ldlr ^-/-) mice, and then Villin Cre (VilCre) mice, enterocyte Scd1 expression in Scd1 ^fl/fl/ldlr ^-/-/VilCre mice was reduced 70%. On Western diet (WD), Scd1 ^fl/fl/ldlr ^-/- mice gained more weight than Scd1 ^fl/fl/ldlr ^-/-/VilCre mice (P < 0.0023). On WD, jejunum levels of lysophosphatidylcholine (LysoPC) 18:1 and lysophosphatidic acid (LPA) 18:1 were significantly less in Scd1 ^fl/fl/ldlr ^-/-/VilCre compared with Scd1 ^fl/fl/ldlr ^-/- mice (P < 0.0004 and P < 0.026, respectively). On WD, Scd1 ^fl/fl/ldlr ^-/-/VilCre mice compared with Scd1 ^fl/fl/ldlr ^-/- mice had lower protein levels of lipopolysaccharide-binding protein (LBP), cluster of differentiation 14 (CD14), toll-like receptor 4 (TLR4), and myeloid differentiation factor-88 (MyD88) in enterocytes and plasma, and less dyslipidemia and systemic inflammation. Adding a concentrate of tomatoes transgenic for the apoA-I mimetic peptide 6F (Tg6F) to WD resulted in reduced enterocyte protein levels of LBP, CD14, TLR4, and MyD88 in Scd1 ^fl/fl/ldlr ^-/- mice similar to that seen in Scd1 ^fl/fl/ldlr ^-/-/VilCre mice. Adding LysoPC 18:1 to WD did not reverse the effects of enterocyte Scd1 knockdown. Adding LysoPC 18:1 (but not LysoPC 18:0) to chow induced jejunum Scd1 expression and increased dyslipidemia and plasma serum amyloid A and interleukin 6 levels in Scd1 ^fl/fl/ldlr ^-/- mice, but not in Scd1 ^fl/fl/ldlr ^-/-/VilCre mice. We conclude that enterocyte Scd1 is partially responsible for LysoPC 18:1- and WD-induced dyslipidemia and inflammation in ldlr ^-/- mice.

Treating the Intestine with Oral ApoA-I Mimetic Tg6F Reduces Tumor Burden in Mouse Models of Metastatic Lung Cancer

Having demonstrated that apolipoprotein A-I (apoA-I) mimetic peptides ameliorate cancer in mouse models, we sought to determine the mechanism for the anti-tumorigenic function of these peptides. CT-26 cells (colon cancer cells that implant and grow into tumors in the lungs) were injected into wild-type BALB/c mice. The day after injection, mice were either continued on chow or switched to chow containing 0.06% of a concentrate of transgenic tomatoes expressing the apoA-I mimetic peptide 6F (Tg6F). After four weeks, the number of lung tumors was significantly lower in Tg6F-fed mice. Gene expression array analyses of jejunum and lung identified Notch pathway genes significantly upregulated, whereas osteopontin (Spp1) was significantly downregulated by Tg6F in both jejunum and lung. In jejunum, Tg6F increased protein levels for Notch1, Notch2, Dll1, and Dll4. In lung, Tg6F increased protein levels for Notch1 and Dll4 and decreased Spp1. Tg6F reduced oxidized phospholipid levels (E06 immunoreactivity) and reduced 25-hydroxycholesterol (25-OHC) levels, which are known to inhibit Notch1 and induce Spp1, respectively. Notch pathway promotes anti-tumorigenic patrolling monocytes, while Spp1 facilitates pro-tumorigenic myeloid derived suppressor cells (MDSCs) formation. Tg6F-fed mice had higher numbers of patrolling monocytes in jejunum and in lung (p < 0.02), and lower plasma levels of Spp1 with reduced numbers of MDSCs in jejunum and in lung (p < 0.03). We conclude that Tg6F alters levels of specific oxidized lipids and 25-OHC to modulate Notch pathways and Spp1, which alter small intestine immune cells, leading to similar changes in lung that reduce tumor burden.

Transgenic tomatoes expressing the 6F peptide and ezetimibe prevent diet-induced increases of IFN-β and cholesterol 25-hydroxylase in jejunum

Feeding LDL receptor (LDLR)-null mice a Western diet (WD) increased the expression of IFN-β in jejunum as determined by quantitative RT-PCR (RT-qPCR), immunohistochemistry (IHC), and ELISA (all P < 0.0001). WD also increased the expression of cholesterol 25-hydroxylase (CH25H) as measured by RT-qPCR (P < 0.0001), IHC (P = 0.0019), and ELISA (P < 0.0001), resulting in increased levels of 25-hydroxycholesterol (25-OHC) in jejunum as determined by LC-MS/MS (P < 0.0001). Adding ezetimibe at 10 mg/kg/day or adding a concentrate of transgenic tomatoes expressing the 6F peptide (Tg6F) at 0.06% by weight of diet substantially ameliorated these changes. Adding either ezetimibe or Tg6F to WD also ameliorated WD-induced changes in plasma lipids, serum amyloid A, and HDL cholesterol. Adding the same doses of ezetimibe and Tg6F together to WD (combined formulation) was generally more efficacious compared with adding either agent alone. Surprisingly, adding ezetimibe during the preparation of Tg6F, but before addition to WD, was more effective than the combined formulation for all parameters measured in jejunum (P = 0.0329 to P < 0.0001). We conclude the following: i) WD induces IFN-β, CH25H, and 25-OHC in jejunum; and ii) Tg6F and ezetimibe partially ameliorate WD-induced inflammation by preventing WD-induced increases in IFN-β, CH25H, and 25-OHC.

ApoA-I mimetic administration, but not increased apoA-I-containing HDL, inhibits tumour growth in a mouse model of inherited breast cancer

Low levels of high-density lipoprotein cholesterol (HDLc) have been associated with breast cancer risk, but several epidemiologic studies have reported contradictory results with regard to the relationship between apolipoprotein (apo) A-I and breast cancer. We aimed to determine the effects of human apoA-I overexpression and administration of specific apoA-I mimetic peptide (D-4F) on tumour progression by using mammary tumour virus-polyoma middle T-antigen transgenic (PyMT) mice as a model of inherited breast cancer. Expression of human apoA-I in the mice did not affect tumour onset and growth in PyMT transgenic mice, despite an increase in the HDLc level. In contrast, D-4F treatment significantly increased tumour latency and inhibited the development of tumours. The effects of D-4F on tumour development were independent of 27-hydroxycholesterol. However, D-4F treatment reduced the plasma oxidized low-density lipoprotein (oxLDL) levels in mice and prevented oxLDL-mediated proliferative response in human breast adenocarcinoma MCF-7 cells. In conclusion, our study shows that D-4F, but not apoA-I-containing HDL, hinders tumour growth in mice with inherited breast cancer in association with a higher protection against LDL oxidative modification.

Tg6F ameliorates the increase in oxidized phospholipids in the jejunum of mice fed unsaturated LysoPC or WD

Mouse chow supplemented with lysophosphatidylcholine with oleic acid at sn-1 and a hydroxyl group at sn-2 (LysoPC 18:1) increased LysoPC 18:1 in tissue of the jejunum of LDL receptor (LDLR)-null mice by 8.9 ± 1.7-fold compared with chow alone. Western diet (WD) contained dramatically less phosphatidylcholine 18:1 or LysoPC 18:1 compared with chow, but feeding WD increased LysoPC 18:1 in the jejunum by 7.5 ± 1.4-fold compared with chow. Feeding LysoPC 18:1 or feeding WD increased oxidized phospholipids in the jejunum by 5.2 ± 3.0-fold or 8.6 ± 2.2-fold, respectively, in LDLR-null mice (P < 0.0004), and 2.6 ± 1.5-fold or 2.4 ± 0.92-fold, respectively, in WT C57BL/6J mice (P < 0.0001). Adding 0.06% by weight of a concentrate of transgenic tomatoes expressing the 6F peptide (Tg6F) decreased LysoPC 18:1 in the jejunum of LDLR-null mice on both diets (P < 0.0001), and prevented the increase in oxidized phospholipids in the jejunum in LDLR-null and WT mice on both diets (P < 0.008). Tg6F decreased inflammatory cells in the villi of the jejunum, decreased dyslipidemia, and decreased systemic inflammation in LDLR-null and WT mice on both diets. We conclude that Tg6F reduces diet-induced inflammation by reducing the content of unsaturated LysoPC and oxidized phospholipids in the jejunum of mice.