In rheumatic heart disease-associated AF, rivaroxaban increased adverse vascular outcomes vs. VKA at 3 y.

SOURCE CITATION: Connolly SJ, Karthikeyan G, Ntsekhe M, et al. Rivaroxaban in rheumatic heart disease-associated atrial fibrillation. N Engl J Med. 2022;387:978-88. 36036525.

Intramuscular Immunization of Streptococcus pyogenes SF370 protein extract and identification of multiple virulence factors through proteomic profiling in RHD induced Balb/c mice.

Group A streptococcus (GAS) and autoimmunity are associated with heart related mitral valve damage, in adults. In this study Balb/c mice were intramuscularly immunized with S. pyogenes SF370 for 4 weeks. Prior to euthanization, physiological parameters like body weight and electrical signalling of the heart were recorded. After euthanization, the heart tissue homogenate was prepared and proteomic alterations were studied using SDS-PAGE and 2D electrophoresis. The expression levels of inflammatory genes like TNFα, IFNγ and TGF-ß were quantified using real time PCR. Insilico analysis was performed to identify the functions of hypothetical proteins and virulence factors involved in the induction of rheumatic carditis. The results showed a reduction in body weight, ulceration, inflammation, cardiac lesions and prolonged PR interval in mice immunized with S. pyogenes SF370, as a result of RHD. The heart related proteins like α-actinin, fatty acid binding protein-heart, myosin light chain 3, hemoglobin subunit alpha, myoglobin regulatory light chain 2, (ventricular/cardiac muscle isoform), myosin-6, troponin-1 were found to be up-regulated when compared with the control. The functional annotation of S. pyogenes (SF370) was carried out by retrieving 1696 identified proteins and 653 hypothetical protein sequences in NCBI genome database. The conserved domain was identified for 505 proteins. The pfam database documented that the super families of 279 sequences and 40 signal peptides enabled the classification of proteins in different categories like biological (20%), cellular (22%) and molecular functions (36%). Putative transcription repair coupling factor and putative lysine aminopeptidase N terminal are the two virulence factors identified by VICMPRED in S. pyogenes SF370. The two identified virulence factors are involved in altering the mice heart proteome and thereby controlling the streptococcus pyogenes infection. Thus, the results of the present study reveals the role of immunogenic proteins in induction of rheumatic carditis and to elucidate the molecular mechanisms leading to autoimmune reactions in Balb/c mice.

Impact of renin-angiotensin system inhibitors on long-term clinical outcomes of patients with rheumatic heart disease.

AIMS: Rheumatic heart disease (RHD) remains a major global health problem. Renin-angiotensin-aldosterone system inhibitors (RAASi) are commonly administered in the treatment of cardiovascular disease, but its role in RHD patients is still limited. We performed a retrospective study to determine the effect of RAASi on long-term outcomes for RHD patients. METHODS AND RESULTS: A 1:1 propensity score matching was implemented to balance baseline characteristics between groups RAASi and non-RAASi. Cox proportional hazards regression model was used to investigate the associations of RAASi with the risks of all-cause mortality, cardiovascular death (CVD), and cerebrovascular death. Binary logistic regression analysis was used to evaluate the associations of RAASi with the risks of 1, 3, and 5 year heart failure (HF) rehospitalization, new-onset atrial fibrillation (AF), and new-onset stroke. A total of 734 RHD patients were enrolled as study participants; nearly half of these participants had combined valve damage (54.4%), worse New York Heart Association functional class status (III and IV, 55.2%), surgical treatment (54.2%), and AF (65.0%). After propensity score matching, 514 RHD patients were finally analysed. RAASi treatment was associated with decreased risks of all-cause mortality [adjusted hazard ratio (HR) = 0.52, 95% confidence interval (CI): 0.37-0.73, P < 0.001], CVD (adjusted HR = 0.48, 95% CI: 0.30-0.76, P = 0.002), and cerebrovascular death (adjusted HR = 0.22, 95% CI: 0.08-0.60, P = 0.003). Further subgroup analysis showed that RAASi treatment was associated with decreased risks of all-cause mortality (adjusted HR = 0.50, 95% CI: 0.31-0.79, P = 0.004), CVD (adjusted HR = 0.48, 95% CI: 0.25-0.91, P = 0.025), and cerebrovascular death (adjusted HR = 0.19, 95% CI: 0.05-0.65, P = 0.008) in RHD patients without surgical treatment, and better effect was observed in RHD patients with surgical treatment on the risks of all-cause mortality (adjusted HR = 0.47, 95% CI: 0.26-0.85, P = 0.012) and CVD (adjusted HR = 0.43, 95% CI: 0.21-0.90, P = 0.024) except cerebrovascular death (adjusted HR = 0.52, 95% CI: 0.08-3.36, P = 0.491). RAASi treatment was associated with decreased HF rehospitalization risk of 1 year [adjusted odds ratio (OR) = 0.38, 95% CI: 0.23-0.61, P < 0.001], 3 year (adjusted OR = 0.43, 95% CI: 0.28-0.68, P < 0.001), and 5 year (adjusted OR = 0.48, 95% CI: 0.30-0.77, P = 0.002) as well as new-onset AF risk (adjusted OR = 0.38, 95% CI: 0.21-0.68, P = 0.001). RAASi treatment had nothing to do with new-onset stroke risk (adjusted OR = 0.80, 95% CI: 0.47-1.38, P = 0.428). CONCLUSION: Renin-angiotensin-aldosterone system inhibitor treatment was significantly associated with decreased risks of mortality, HF rehospitalization, and new-onset AF in RHD patients in median 5.9 year follow-up.

Group A streptococcal M-protein specific antibodies and T-cells drive the pathology observed in the rat autoimmune valvulitis model.

Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) are autoimmune mediated diseases triggered by group A streptococcal (GAS) infections. Molecular mimicry between GAS M-proteins and host tissue proteins has been proposed as the mechanism that initiates autoreactive immune responses in ARF/RHD. However, the individual role of antibodies and T-cells specific for GAS M-proteins in the pathogenesis of autoimmune carditis remains under-explored. The current study investigated the role of antibodies and T-cells in the development of carditis in the Lewis rat autoimmune valvultis (RAV) model by transferring serum and/or splenic T-cells from rats previously injected with GAS recombinant M5 protein. Here we report that serum antibodies alone and serum plus in vitro expanded rM5-specific T-cells from hyperimmune rats were capable of transferring carditis to naïve syngeneic animals. Moreover, the rats that received combined serum and T-cells developed more severe carditis. Recipient rats developed mitral valvulitis and myocarditis and showed prolongation of P-R intervals in electrocardiography. GAS M5 protein-specific IgG reactivity and T-cell recall response were also demonstrated in recipient rats indicating long-term persistence of antibodies and T-cells following transfer. The results suggest that both anti-GAS M5 antibodies and T-cells have differential propensity to induce autoimmune mediated carditis in syngeneic rats following transfer. The results highlight that antibodies and effector T-cells generated by GAS M protein injection can also independently home into cardiac tissue to cross-react with tissue proteins causing autoimmune mediated immunopathology.

Drug-Induced- or Rheumatic- Valvular Heart Disease in Patients Exposed to Benfluorex?

There is a risk of misdiagnosis between benfluorex-induced VHD and acute rheumatic fever (ARF)-related VHD due to common characteristics of both etiologies. We aimed at estimating the probability for a patient exposed to benfluorex presenting with VHD to have, at the same time, a history of ARF-related VHD. Such epidemiological approach could help at reducing the risk of misdiagnosis. We used INSEE data and related literature as well as various modeling hypotheses to drive and test a formula for calculating the probability of a patient presenting with VHD and a history of benfluorex intake to have a prior history of ARF-related VHD. Different scenarios were estimated by a Markov model on the life course of people born in France between 1940 and 1960. Sensitivity analyses were performed under these scenarios. According to the different scenarios and gender, the probability that a patient born between 1940 and 1960 presenting with VHD and a history of benfluorex intake would have had a prior history of ARF-related VHD varied from 0.2% to 2.7%. The probabilities by the year of birth were as follows: 0.8%-2.7% for a patient born in 1940, < 0.5% in all scenarios for patients born after 1955, and < 0.2% in all scenarios for patients, born in 1960. Our results indicate that the burden of ARF-related VHD is low in the patient population exposed to benfluorex. The probability of ARF related VHD should not be over-estimated in the diagnostic procedure of VHD.

Changes in the expression of Th17 cell-associated cytokines in the development of rheumatic heart disease.

BACKGROUND: Autoimmunity plays a critical role in the development of rheumatic heart disease (RHD). Recent studies have linked Th17 cells to the autoimmune mechanism associated with RHD. This study aimed to investigate changes in Th17 cell-related cytokine expression in acute and chronic RHD. METHODS: We established a Lewis rat model of experimental RHD, which was induced by inactivated Group A streptococci and complete Freund's adjuvant. After 7- and 24-week intervention treatments, we measured serum levels of interleukin-17 (IL-17) and IL-6, key cytokines associated with Th17 cells, using a Luminex liquichip method, and levels of IL-17 and IL-6 in heart tissues using immunohistochemical assays. Moreover, expression levels of IL-17, IL-21, IL-6, and IL-23 in mitral valve tissues of human RHD patients were also measured using immunohistochemistry. RESULTS: Compared with the normal control group, serum IL-17 and IL-6 concentrations were significantly increased, and the expression levels of IL-17 and IL-6 in the mitral valve were also significantly increased in 7- or 24-week RHD rats (P<.017). Compared with the control group, expression of IL-17, IL-21, IL-6, and IL-23 in mitral valve tissues was significantly increased in RHD patients (P<.05). CONCLUSIONS: Our study suggested that the increased expression of Th17 cell-associated cytokines might play an important role in the pathogenesis and development of RHD.

An alternative technique for the induction of autoimmune valvulitis in a rat model of rheumatic heart disease.

We currently use a rat model in our investigations into human rheumatic heart disease (RHD). This model traditionally involves footpad immunization with antigen emulsified in complete Freund's adjuvant (CFA). Trials to find an alternative adjuvant to CFA which produced a Th1 type response in the rats resulting in carditis were unsuccessful. However, hock immunization was found to produce the desired valvular pathology without the adverse inflammatory side-effects associated with CFA. We therefore consider the hock an ideal site for immunization, particularly when using CFA.