Oral Tolerization with Mycobacterial Heat Shock Protein 65 Reduces Chronic Experimental Atherosclerosis in Aged Mice

Abstract

Background: Atherosclerosis is a chronic inflammatory disease of the artery wall where both innate and adaptive immunity play important roles. Modulation of the immune response against the stress protein antigen, heat shock protein (HSP) 60, by administration of mycobacterial HSP65 (mbHSP65) orally and/or nasally shows promising therapeutic results in young animals in the sense of less severe experimental atherosclerosis; however, the case of aged animals with already established atherosclerosis has so far never been investigated. Objective: To investigate if mbHSP65 immunization would further accelerate atherosclerotic progression in aged ApoE^-/- mice (18 months old) with already long-established atherosclerosis and if these mice could be orally tolerized against mbHSP65. Methods: Aged wild-type (WT) and ApoE^-/- mice (65 weeks) were immunized and/or orally treated with mbHSP65 and then either kept on normal chow or changed to high-cholesterol diet (HCD). Atherosclerosis was assessed by en face analysis and the number of CD4⁺CD25⁺FoxP3⁺ T regulatory cells (Tregs) was assessed by flow cytometry in lymph node and spleen cells. Total cholesterol and triglyceride levels were determined. Soluble mammalian HSP60 and anti-mouse HSP60 (mHSP60) and anti-mbHSP65 antibodies were detected by enzyme-linked immunosorbent assay. Results: As expected, aged WT mice had only minor lesions in the aorta, which did not change under HCD for 14 weeks. Aged ApoE^-/- mice already had large complicated plaques, which increased in size under HCD. mbHSP65 immunization led to a significant aggravation of atherosclerosis in both WT and ApoE^-/- mice irrespective of the nature of their diet. This increase was accompanied by increased titers of both anti-mHSP60 and anti-mbHSP65 antibodies in the circulation. The increased plaque formation could be significantly diminished with oral mbHSP65 tolerization. An increased number of Tregs and lower or unchanged levels of cholesterol and triglycerides were associated with the reduced size of aortal lesions. Conclusion: Oral tolerization against mbHSP65 could be used both to prevent and to treat chronic atherosclerosis in aged individuals.

Age‐related changes in ocular mucosal tolerance: Lessons learned from gut and respiratory tract immunity

“…Aged (18‐months) ApoE −/− mice immunized with mycobacterial heat‐shock protein 65 and subjected to a high cholesterol diet showed atherosclerosis progression. In contrast, oral administration of mycobacterial heat‐shock protein 65 before immunization decreased the extension of plaques and increased the frequency of splenic Tregs [64,65].…”

Mycobacterium tuberculosis: An Adaptable Pathogen Associated With Multiple Human Diseases

“…Consistently, mycobacterial HSP65 and the human homolog HSP60 are detected at heightened serum levels in atherosclerotic patients (Xu et al, 1993 ; Zhu et al, 2001 ). In addition, high-cholesterol diet-induced atherosclerotic animals immunized with HSP65 display an accelerated progression of disease, while oral tolerization with HSP65 can block the advanced formation of atherosclerotic plaques (Zhang et al, 2012 ; Wick et al, 2017 ). Atheroma has long been considered as a chronic infectious disease associated with multiple pathogens, including M. tuberculosis, Chlamydia pneumoniae, Helicobacter pylori , and periodontal bacteria (Anestad et al, 2001 ; Huaman et al, 2015 ).…”

Structure-Based Virtual Screening of Benzaldehyde Thiosemicarbazone Derivatives against DNA Gyrase B of Mycobacterium tuberculosis

“…Here, both compounds 20 and 21 have more or less similar binding energies. Other compounds, namely, 1,5,6,7,8,9,10,11,12,13,14,15,17,19,22,24,25,26,27,28,29, and 30 have their binding energies ranging from −6.0 to −6.9 kcal/mol. Also, the binding energies of compounds 2, 3, 4, 14, 16, 18, and 23 range from −5.6 to −5.9 kcal/mol.…”

“…This promotes the diseased macrophage necrosis and, thereby, discharges the intracellular bacteria, which infect novel cells and invade other tissues [ 8 ]. Recent reports suggest that TB is also related with many other human complications, namely, autoimmune diseases (sarcoidosis: M. tuberculosis activates toll-like receptors, thereby, promoting pulmonary sarcoidosis [ 9 ]; systemic lupus erythematosus: immunosuppressive therapy and several immune abnormalities cause reactivation and diffusion of TB [ 10 ]), metabolic syndromes (diabetes mellitus: promotes the proliferation of mycobacterium [ 11 ]; atherosclerosis: mycobacterium rushes the development of atherosclerosis [ 12 ]), and pulmonary complications (pneumonia: TB infection rises the risk of secondary bacterial infection in children [ 13 ]; chronic obstructive pulmonary disease: pulmonary TB may alter the lung architecture [ 14 ]; lung cancer: TB is one of the risk factors for the development of lung cancer [ 15 , 16 ]).…”