Plausible Role of NLRP3 Inflammasome and Associated Cytokines in Pathogenesis of Rheumatic Heart Disease.

Rheumatic heart disease (RHD) is a post-streptococcal sequela caused by Streptococcus pyogenes. The global burden of disease is high among people with low socio-economic status, with significant cases emerging every year despite global eradication efforts. The current treatment includes antibiotic therapies to target strep throat and rheumatic fever and valve replacement strategies as a corrective measure for chronic RHD patients. Valvular damage and valve calcification are considered to be the end-stage processes of the disease resulting from impairment of the endothelial arrangement due to immune infiltration. This immune infiltration is mediated by a cascade of events involving NLRP3 inflammasome activation. NLRP3 inflammasome is activated by wide range of stimuli including bacterial cell wall components like M proteins and leukocidal toxins like nicotinamide dehydrogenase (NADase) and streptolysin O (SLO) and these play a major role in sustaining the virulence of Streptococcus pyogenes and progression of RHD. In this review, we are discussing NLRP3 inflammasome and its plausible role in the pathogenesis of RHD by exploiting the host-pathogen interaction mainly focusing on the NLRP3 inflammasome-mediated cytokines IL-1ß and IL-18. Different therapeutic approaches involving NLRP3 inflammasome inactivation, caspase-1 inhibition, and blockade of IL-1ß and IL-18 are discussed in this review and may be promising for treating RHD patients.

Safety & efficacy of an intravasal, one-time injectable & non-hormonal male contraceptive (RISUG): A clinical experience.

Background & objectives: For improved male contraception, a new polymeric drug molecule - Reversible Inhibition of Sperm under Guidance (RISUG) has been synthesized and has been found to be effective, safe and reversible in various animal species. Phase-I and phase-II clinical trials have confirmed its safety and contraceptive efficacy. The present study was undertaken as a multicentric-limited phase-III clinical trial to test the efficacy and safety of RISUG in human volunteers. Methods: One hundred and thirty nine young males each having at least two children and living with wife were given 120 µl of RISUG as bilateral vas intraluminal injection. After the single-dose administration, the individuals were followed in respect of general health and semen parameters. Their wives were also followed particularly to determine onset of pregnancy. Results: During the six month follow up, the health of male volunteers and their wives was normal with no significant adverse effects. Temporary scrotal enlargement and mild scrotal and inguinal region pain were manifested in most individuals and resolved within one month without any routine activity impairment. In six individuals, there was injection procedure failure and azoospermia was not achieved. The other 133 individuals had either severe oligozoospermia or azoospermia at the first semen examination one month following RISUG injection; 82.7 per cent individuals had continued azoospermia in the month following first semen examination onwards and the rest 17.3 per cent manifested azoospermia within three to six months. Interpretation & conclusions: RISUG intravasal injection appears to be a safe clinical procedure with no significant adverse effects and has high sustained contraceptive efficacy. The localized intervention and continued contraceptive action on single-dose administration were significant features of the RISUG technology.

Dysbiosis Disrupts Gut Immune Homeostasis and Promotes Gastric Diseases.

Perturbation in the microbial population/colony index has harmful consequences on human health. Both biological and social factors influence the composition of the gut microbiota and also promote gastric diseases. Changes in the gut microbiota manifest in disease progression owing to epigenetic modification in the host, which in turn influences differentiation and function of immune cells adversely. Uncontrolled use of antibiotics, chemotherapeutic drugs, and any change in the diet pattern usually contribute to the changes in the colony index of sensitive strains known to release microbial content in the tissue micromilieu. Ligands released from dying microbes induce Toll-like receptor (TLR) mimicry, skew hypoxia, and cause sterile inflammation, which further contributes to the severity of inflammatory, autoimmune, and tumorous diseases. The major aim and scope of this review is both to discuss various modalities/interventions across the globe and to utilize microbiota-based therapeutic approaches for mitigating the disease burden.

Interleukin-10: Role in increasing susceptibility and pathogenesis of rheumatic fever/rheumatic heart disease.

Streptococcus pyogenes (group A streptococcus) causes rheumatic fever (RF) which later progresses towards rheumatic heart disease (RHD) in the susceptible individuals. RF and RHD both contribute towards increasing global burden of disease, especially in developing countries. RHD is one of the most common acquired heart diseases causing permanent damage to heart valves which ultimately leads to heart failure. In RHD, heart valve lesions are formed which are mediated by autoimmune reaction between streptococcal antigens (M protein and group A carbohydrate epitope GlcNAc) and heart tissues. On the other hand, inflammatory response generated by cytokines promotes chronicity of the disease. Varying concentrations of interleukin-10 (IL-10) in patients and controls are reported and are also found to be associated with IL-10 gene polymorphism in RF/RHD patients. Although the effect of IL-10 gene polymorphism on the functionality of IL-10 is unknown, many investigations suggest an important role of IL-10 and its polymorphism in immune regulation and progression of disease in RF/RHD. This review summarizes the studies based on association of interleukin-10 with RHD in different populations to understand the role of IL-10 in susceptibility and pathogenesis of the disease.

Association of rheumatic fever & rheumatic heart disease with plausible early & late-stage disease markers.

BACKGROUND & OBJECTIVES: Rheumatic fever (RF) and rheumatic heart disease (RHD) are the autoimmune sequelae caused by Group A Streptococcus. RHD still remains a major concern in the developing countries due to its poor diagnosis, lack of vaccines and social awareness among population. This study was aimed to identify the plausible early- and late-stage disease markers associated with RF/RHD. METHODS: A total of 84 patients with confirmed pharyngitis (n=18), RF (n=23) and RHD (n=43) were included in the comparative analysis of different factors involved in host-pathogen interaction during RF/RHD pathogenesis. RESULTS: This study revealed high titre of serum antistreptolysin O (ASO) antibody in pharyngitis compared to RF and RHD patients, whereas procollagen type 1 C-peptide (PICP) level was elevated in RHD which showed an inverse correlation with serum ASO titre. The significant elevation of serum anti-peptide associated with RF (PARF) antibody in RF patients was correlated as a probable stage-specific determinant. In addition, pro-inflammatory cytokine profile revealed high levels of interleukin-12 (IL-12)/IL-23p40, IL-17A in RF, whereas IL-6 concentration was higher in RHD compared to healthy controls. INTERPRETATION & CONCLUSIONS: The overall assessment of the factors/ disease markers involved in host-pathogen interaction in RF/RHD may be suggestive of plausible disease marker in different groups of patients. Further studies with larger sample need to be done to better understand RF/RHD pathogenesis.

Genome tuning through HLA and KIR gene clusters impact susceptibility to dengue.

Dengue is amongst the most prevalent viral diseases which globally affects millions of individuals annually and renders billions at risk, particularly in tropical and sub-tropical nations. WHO estimated 100-400 million infections each year and reported 4.2 million active cases in 2019 worldwide. The infection is caused by arthropod-transmitted dengue virus which is known to have 5 serotypes (DENV1-5). Most of the cases show mild clinical symptoms; though others may develop severe forms viz; dengue hemorrhagic fever and dengue shock syndrome. Though limited literature suggests the population-specific genetic influence on susceptibility and the clinical course of dengue; the genetic propensity of dengue is largely unknown in most ethnicities. In this context, the human leukocyte antigen (HLA) system represents the most polymorphic region of the human genome and is crucial for the initiation of an appropriate immune response. In most of the genome-wide association studies, the HLA complex is the most significantly linked genetic region with susceptibility or protection towards various infectious and noninfectious diseases. Killer immunoglobulin-like receptors represent another highly variable system present on the surface of natural killer (NK) cells which regulate the activity of NK cells through interactions with their cognate HLA ligands. It is conceivable that the interaction of HLA-Killer immunoglobulin-like receptors systems influences the host susceptibility towards dengue infection as well the disease outcome. Here we attempt to review these parameters in dengue infection and disease outcome. Further detailed investigations are warranted towards the identification of novel susceptibility markers and targeted therapeutic interventions.

Association of HLA-DRB1*14 with rheumatic heart disease patients from Chandigarh, North India.

CONTEXT: Acute rheumatic fever (ARF)/rheumatic heart disease (RHD) is a major cause of morbidity and mortality in India, yet, few studies are available on susceptibility markers. OBJECTIVE: To associate human leukocyte antigen (HLA) class II alleles with north Indian RHD patients as genetic susceptibility markers. MATERIALS AND METHODS: HLA alleles were analysed using sequence specific primer-polymerase chain reaction and nucleotide sequencing, while HLA-B27 expression by flowcytometry. RESULTS: Few HLA-DQB1/DRB1 alleles were associated with RHD and HLA-DRB1*14 gene polymorphism revealed two single nucleotide polymorphisms (SNPs) in patients. Bioinformatic predictions showed influence of SNPs on protein function. HLA-B27 was positive in 42.85% ARF patients. CONCLUSION: The study showed association of different HLA class II alleles with RHD in North Indian population.

Group A Streptococcus Infections: Their Mechanisms, Epidemiology, and Current Scope of Vaccines.

Group A streptococci (GAS) are gram-positive, cocci-shaped bacteria that cause a wide variety of infections and are a cause of significant health burden, particularly in lower- and middle-income nations. The GAS genome contains a number of virulence factors such as the M-protein, hyaluronic acid, C5a peptidase, etc. Despite its significant health burden across the globe, a proper vaccine against GAS infections is not yet available. Various candidates for an effective GAS vaccine are currently being researched. These are based on various parts of the streptococcal genome. These include candidates based on the N-terminal region of the M protein, the conserved C-terminal region of the M protein, and other parts of the streptococcal genome. The development of a vaccine against GAS infections is hampered by certain challenges, such as extensive genetic heterogeneity and high protein sequence variation. This review paper sheds light on the various virulence factors of GAS, their epidemiology, the different vaccine candidates currently being researched, and the challenges associated with M-protein and non-M-protein-based vaccines. This review also sheds light on the current scenario regarding the status of vaccine development against GAS-related infections.

Association between Handwashing Behavior and Infectious Diseases among Low-Income Community Children in Urban New Delhi, India: A Cross-Sectional Study.

Diarrheal diseases and respiratory infections (RI) are two leading causes of childhood mortality in low and middle-income countries. Effective handwashing at critical time-points may mitigate these diseases. However, there is a lack of published data investigating this association in school-aged children in India. This study is part of a larger prospective handwashing intervention study in a low-income community in New Delhi, India examining the associations between handwashing behavior and diarrhea and RI in schoolchildren. This current study reports the findings of the baseline survey administered to 272 mother-child dyads. Children aged 8-12 years, and their mothers, were recruited from six schools. A baseline questionnaire was used to collect sociodemographic data, handwash behavior, and mother-reported recent diarrhea and RI incidence among the children. Handwashing before and after preparing food, after defecation, and after cleaning dishes significantly reduced the odds of diarrhea by over 70%, and of RI by over 56%. Using a clean cloth after handwashing lowered odds of diarrhea and RI by 72% and 63% respectively. Around 60% of the participants believed that handwashing could prevent diarrhea and RI in their children. There was a low prevalence of handwashing at critical time-points and a poor perception regarding handwashing benefits. To improve handwashing behavior, hygiene promotion programs need to understand what motivates and hinders handwashing in vulnerable populations.

Antibiotic Resistance in Microbes from Street Fruit Drinks and Hygiene Behavior of the Vendors in Delhi, India.

Microbial contamination of fruit juices has caused major outbreaks, leading to significant morbidity and mortality in developing countries. The inept hygiene and safety practices followed by the juice vendors are the leading risk factors of the microbial contamination of juices. In this pilot study, the five most crowded markets in urban Delhi, including Kamla Nagar, University of Delhi (north campus), Tilak Nagar, Chandni Chowk, and Rohini, were selected for a questionnaire survey on the fruit juice vendors and the sampling of water used for juice preparation as well as sugarcane, orange, and mix fruit juices collected from these markets for the enumeration of total bacterial count (TBC), Escherichia coli, Salmonella, and Vibrio. Antibiotic susceptibility tests were performed using ampicillin, cefotaxime, chloramphenicol, ciprofloxacin, and imipenem. The results indicated that the majority of the vendors were not following hygiene and safety practices when compared with the recommended standard safety practices. The use of municipal water by 95% of vendors with high TBC counts might have been the major source of microbial contamination in all types of fruit juices. E. coli and Salmonella contaminations were high in sugarcane (2 × 105 colony forming units (CFU)/mL) and mix fruit (2.2 × 105 CFU/mL) juice samples, respectively. On the other hand, Vibrio was found to be absent in almost all juice samples except for orange juice. All strains were found to be susceptible to chloramphenicol, but resistant to ampicillin and cefotaxime. Only a few strains were resistant to ciprofloxacin, and only E. coli strains were resistant to imipenem. Taken together, the overall microbiological standards of fruit juices served by street vendors were not within the acceptable limits, perhaps due to the poor quality of water used to prepare juices and poor hygiene and safety practices followed by the vendors. More importantly, the isolated microbes demonstrated resistance to ampicillin and cefotaxime, which may have pressing public health implications. Post hoc power analyses identified the minimum sample size required for 80% power.

Impact of Socio-Economic Factors on Increased Risk and Progression of Rheumatic Heart Disease in Developing Nations.

PURPOSE OF REVIEW: Rheumatic heart disease (RHD) is a global health concern especially in low-income settings. Morbidity and mortality data from the World Health Organization (WHO) and global burden studies emphasizes on the prioritization of RHD on a global platform. Genetic, environmental, and socio-economic factors determine the sustainability and progression of RHD in various populations. In developing countries, low socioeconomic status (SES) is a vast and inevitable challenge in combating RHD. Concurrence between low SES and RHD has been well documented by several studies, but there is a paucity of data to understand comprehensive interdependency of low SES and RHD. In this review, we have made an attempt to present the overall correlation between SES and increased risk of RHD by examining and highlighting the role of key components of SES in different populations throughout the world as reported in literature. RECENT FINDINGS: In the recent past, developed countries have reported success stories regarding amelioration of RHD due to improved living conditions and better access to healthcare. Whereas, in low-income settings, various socio-economic parameters such as overcrowding, illiteracy, low monthly income, maternal employment, rural dwelling, and less access to good quality healthcare are the core challenges which significantly impose an increased risk of RHD. Overall, there is significant evidence which confirms the role of SES in increased risk and progression of RHD, but vigorous and systematic studies need to be done to evaluate the cumulative effect of SES. Also, it will be helpful in dissemination of efficient primary and secondary prevention of RHD. Additionally, another aspect of this review was to assess the plausible impact of low SES on the clinical spectrum of RHD which might characterize SES as an authoritative marker for disease progression and severity.

T cell subsets: an integral component in pathogenesis of rheumatic heart disease.

Acute rheumatic fever (ARF) is a consequence of pharyngeal infection of group A streptococcal (GAS) infection. Carditis is the most common manifestation of ARF which occurs in 30-45% of the susceptible individuals. Overlooked ARF cases might further progress towards rheumatic heart disease (RHD) in susceptible individuals, which ultimately leads to permanent heart valve damage. Molecular mimicry between streptococcal antigens and human proteins is the most widely accepted theory to describe the pathogenesis of RHD. In the recent past, various subsets of T cells have been reported to play an imperative role in the pathogenesis of RHD. Alterations in various T cell subsets, viz. Th1, Th2, Th17, and Treg cells, and their signature cytokines influence the immune responses and are associated with pathogenesis of RHD. Association of other T cell subsets (Th3, Th9, Th22, and TFH) is not defined in context of RHD. Several investigations have confirmed the up-regulation of adhesion molecules and thus infiltration of T cells into the heart tissues. T cells secrete both Th type 1 and type 2 cytokines and these auto-reactive T cells play a key role in progression of heart valve damage. In this review, we are going to discuss about the role of T cell subsets and their corresponding cytokines in the pathogenesis of RHD.

A hospital-based study of socioeconomic status and clinical spectrum of rheumatic heart disease patients of Assam, North-East India.

Objective The aim of this study was to assess the impact of socioeconomic factors in increased prevalence of rheumatic heart disease and its clinical spectrum in Assam, North-East India. Method A case-control questionnaire-based study of 100 echocardiography confirmed rheumatic heart disease cases with age- and sex-matched healthy controls from Assam medical college and hospital in Dibrugarh, Assam was conducted. Results There was a trend toward increased risk of rheumatic heart disease and its clinical spectrum with respect to low socioeconomic status. Three parameters were found to be statistically significant in posing increased risk towards rheumatic heart disease: rural dwelling location ( p < 0.0001, odds ratio (OR) 4.1, 95% confidence interval (CI = 2.29-7.45), low monthly income ( p < 0.001, OR=9.5, 95% CI = 4.99-18.1) and education status ( p < 0.05, OR=9.5, 95% CI = 1.866). Out of the severe cases of mitral stenosis, mitral regurgitation and aortic regurgitation, 69.6%, 58.3% and 34% patients were of low socioeconomic status. Conclusion Socioeconomic factors can be of significant importance in increased prevalence of rheumatic heart disease and might also influence the clinical spectrum of the disease. Increased awareness and up-gradation of socioeconomic status might ameliorate the prevalence of rheumatic heart disease.

Immune response against M protein-conserved region peptides from prevalent group A Streptococcus in a North Indian population.

BACKGROUND: Group A streptococci (GAS) cause infections with a high prevalence in most developing countries. A GAS vaccine under trial that is based on the amino-terminus of the M protein provides type-specific immunity, and hence seems ineffective in India because of heterogeneous emm types. However, the conserved C-terminal region of the M protein protects against multiple serotypes. In this paper, the immune response generated against the conserved C-repeat region of the M protein was checked in an Indian population to establish their vaccine candidature. METHODS: When screened for GAS, patients with pharyngitis, rheumatic fever/rheumatic heart disease (RF/RHD), and invasive disease showed heterogeneous emm types, out of which five prevalent types (1-2, 11, 49, 75 and 112) were selected for the study. The C-terminal region of their M proteins showed conserved C1-, C2-, and C3-repeats. The C1-repeat was more diverse and had two different J14-like sequences. Peptides to these C-terminal regions (J14.1 and J14-R6) were designed. Antibodies against these peptides were analyzed using the sera of 130 GAS-infected volunteers. RESULTS: Serum antibodies were significantly higher in patients with acute rheumatic fever, RHD, and invasive disease than in patients with pharyngitis or the healthy controls. The serum antibodies to these peptides was higher in teenagers and adults than in children. CONCLUSION: Results showed an association between streptococcal disease progression and the age-related development of immunity to the conserved regions. Hence, these peptides could be considered protective in impeding streptococcal infections worldwide.

Development and field evaluation of a method for detecting carbapenem-resistant bacteria in drinking water.

In this study, a fluorogenic heterotrophic plate count test for drinking water was modified in order to detect the presence of carbapenem-resistant bacteria. Antimicrobial agents and concentrations were selected based on recoveries of known carbapenem-resistant and carbapenem-susceptible strains inoculated into simulated samples. The modified method was field-tested on 19 drinking water samples from the New Delhi, India distribution system. Samples exhibiting fluorescence indicated bacterial growth in the presence of the supplemented antimicrobial agents, and organisms from these samples were cultured. Twenty-one Gram-negative isolates were identified from nine of the 19 samples and the meropenem minimum inhibitory concentrations were determined. Ultimately, eight carbapenem-resistant organisms were isolated from five sampling sites within the New Delhi water distribution system.

Antimicrobial susceptibility pattern of ß-haemolytic group A, C and G streptococci isolated from North India.

The objective of this study was to determine the antibiotic resistance amongst beta-haemolytic streptococci (BHS) from North India. A total of 155 BHS isolates, comprising group A streptococci (GAS) (102), group C streptococci (GCS) (25) and group G streptococci (GGS) (28), collected from patients with pharyngitis, rheumatic fever, skin disease and invasive disease were analysed for their antimicrobial susceptibility to 20 antibiotics using the Kirby-Bauer disc diffusion method. The MICs of penicillin, tetracycline, clarithromycin, azithromycin and erythromycin were also determined using the HiComb test, following the Clinical and Laboratory Standards Institute guidelines. The results showed that 37.4% of BHS isolates were susceptible to all antibiotics and 19.4% were highly resistant to tetracycline; however, only 2.6-5.2% were resistant to macrolides. The tetracycline resistance (P<0.05) of BHS was found to be statistically significant. GAS isolates from different sources of infection also showed statistically significant antibiotic resistance to azithromycin (P=0.029). Multi-drug resistance was found irrespective of streptococcal emm types. No association between GAS emm types and drug resistance was seen. MIC determination showed all isolates to be susceptible to the five antibiotics tested, except for two GAS and one GGS isolates that were resistant to clarithromycin, and one GAS skin isolate that was resistant to tetracycline. This study suggests that the variation in antibiotic resistance amongst BHS isolates from North India is independent of the isolation source and emm type distribution, hence emphasizing the need for a longitudinal surveillance in different regions of India.

Immune responsiveness during disease progression from acute rheumatic fever to chronic rheumatic heart disease.

Streptococcus pyogenes causes pharyngitis in school age children, which if left untreated causes acute rheumatic fever (ARF) that later progress toward rheumatic heart disease (RHD). The pathogenesis of this disease and its progression as post infectious squeal is not well understood. In this study, percentages of CD4(+) and CD8(+) T-cells were compared among patients of ARF, RHD and Chronic RHD using flow cytometer. The production of Th1/Th2 cytokines from serum and endothelial cells of damaged and normal heart valves was also analyzed using flow cytometer. Results showed an inverse proportion of CD4(+) and CD8(+) T-cell numbers in ARF and RHD patients. Cytokine assay demonstrated a switch-over from Th1 to Th2 type, as the disease progressed. We observed significantly high IL-6 in ARF patients and high TNF-α in early RHD patients which allowed us to construct a hypothesis, that, during initial infection phase, lot of antibodies are produced (via IL-6) and TNF-α has a role in disease progression and tissue damage during RHD phase.