ROLE OF PI3K-AKT PATHWAY IN THE AGE ASSOCIATED DECLINE IN TLR MEDIATED ACTIVATION OF INNATE AND ADAPTIVE IMMUNE RESPONSES

Immunosenescence results in reduced immune response to infections with Streptococcus pneumoniae as well as to pneumococcal polysaccharide vaccines. The antibody response to the capsular polysaccharide (CPS) provides protection against S. pneumoniae infection. CPS immunoresponse is T cell independent and needs the macrophage-derived cytokines such as IL-12, IL-6 and IL-1β to elicit an antibody response. We showed a cytokine dysregulation, i.e. a decrease in IL-12, IL-6 and TNF-α but an increase in IL-10, in the aged (18-24 months old comparable to \u3e65 years in human) compared to young adult mouse (8-12 weeks less than 65 years old) splenic macrophages (SM) or bone marrow derived macrophages (BMDM) activated via TLR4, TLR2 or TLR9 as well as heat killed Streptococcus pneumoniae (HKSP). There is also an age-associated defect in splenic B cells in the production of IgG3 upon stimulation with these ligands. A microarray analysis in SM followed by validation by both qt-RTPCR and western blots indicated that this age-associated defect in aged SM, BMDM and B cells was due to a heightened activity of the PI3K-Akt signaling pathway. We hypothesized that the senescence of immune responses in macrophages and B cells is due to an increase in activity of PI3K/Akt and decrease in the activity of GSK-3, the downstream kinase. Inhibition of the PI3-kinase with either LY294002 or Wortmannin restored the TLR2, 4, 9 and HKSP induced cytokine phenotype of the aged to that of the young adult in both the SM and BMDM and an enhanced IgG3 production in aged mice. We also showed that inhibition of glycogen synthase kinase-3 (GSK-3) the downstream target of the PI3K-Akt signaling pathway with SB216763 in SM, BMDM and B cells resulted in an enhancement in production of IL-10, IL-6 and IL-1β by macrophages and in B cell activation. Treatment of B cells with SB216763 in the presence of ligands for TLR-1/2, 4 or 9 as well as HKSP under in vitro conditions led to enhanced production of IgG3 and IgA, plasma cell formation and a slight increase in the proliferation of the B-cells with no adverse effects on the viability of the cells. Therefore, targeting the PI3K-AKT-GKS-3 signaling pathway could rescue the intrinsic signaling defect in the aged macrophages, increase IL-12 and IL-6, and enhance anti-CPS antibody responses

Role of Phosphoinositide 3-Kinase – Akt Signaling Pathway in the Age-Related Cytokine Dysregulation in Splenic Macrophages Stimulated via TLR-2 or TLR-4 Receptors

Age-associated defects in both B-lymphocytes and macrophages in elderly result in a reduction in the efficacy of vaccines to many Gram positive bacteria like Streptococcus pneumoniae. Splenic macrophages from aged mice have been shown to have a defect in production of pro-inflammatory cytokines (IL-6, IL-12, IL-1β, TNF-α) but exhibit increased production of IL-10 upon TLR4 ligation. Here we showed that aged macrophages demonstrate similar cytokine dysregulation phenotype upon stimulation with TLR2 ligands, or killed S. pneumoniae. We hypothesized that an age-associated increase in activity of phosphatidyl inositol 3-kinase (PI3K)-Akt signaling pathway may be playing a causal role in the age-associated cytokine dysregulation. We found that gene expression of both the regulatory (p85β) and the catalytic (p110δ) subunits of Class IA PI3K is higher in aged than in young splenic macrophages. The age-associated increase in the activity of PI3K was also demonstrated by an upregulation of P-Akt and its downstream target, glycogen synthase kinase-3 (GSK-3). Inhibition of PI3K enhanced induction of pro-inflammatory cytokines, by TLR-2/TLR-1, TLR-2/TLR-6 and TLR-4 ligands as well as heat killed S. pneumoniae (HKSP). Therefore, targeting PI3-Kinase could rescue cytokine dysregulation in aged macrophages and enhance the relevant pro-inflammatory cytokines needed to support B-cell activation and differentiation

Communication as the key to guide workforce development in the health sector in public stakeholder partnerships: a case study in Liberia

AbstractBackgroundTo improve the academic capacity of disciplines that contribute directly to the training of the health-care workforce in Liberia, the University of Liberia, in partnership with American counterparts at Indiana University and University of Massachusetts, launched the Center for Excellence in Health and Life Sciences, funded by USAID and Higher Education for Development.MethodsWith a participatory approach, academics, government representatives, and community constituents developed a Certificate in Public Health (CPH). Targeting midlevel governmental health workers, the programme model combined traditional coursework with intensive community-based practice experiences, allowing students and faculty to move outside traditional academic and technical disciplinary boundaries. With a participatory approach to define measurable outcomes that were relevant to health-care planning for the country, the programme continually aligned its content with stakeholder expectations.FindingsThe first cohort of ten students completed the core course curriculum plus 90 h of internship activity at five government facilities around Monrovia. Findings are the facilitating and challenging factors associated with the programme's development, implementation, and evaluation. Challenges include increased home-based delivery by semitrained traditional midwives and increase in malaria, diarrhoea, and acute respiratory infection in children younger than 5 years.InterpretationThe Ministry of Health and Social Welfare has already provided a framework to guide the rehabilitation of the health sector in a plan called Rebuilding Basic Health Services. To align public institution outcomes to workforce needs, communication, collaboration, and synergy between stakeholders is key. Tracking the improvement of data being reported and the health outcomes of communities served by the CPH graduates will be important. Further analysis needs to be done to ensure training fills health worker gaps.FundingUSAID

Harnessing case isolation and ring vaccination to control Ebola.

As a devastating Ebola outbreak in West Africa continues, non-pharmaceutical control measures including contact tracing, quarantine, and case isolation are being implemented. In addition, public health agencies are scaling up efforts to test and deploy candidate vaccines. Given the experimental nature and limited initial supplies of vaccines, a mass vaccination campaign might not be feasible. However, ring vaccination of likely case contacts could provide an effective alternative in distributing the vaccine. To evaluate ring vaccination as a strategy for eliminating Ebola, we developed a pair approximation model of Ebola transmission, parameterized by confirmed incidence data from June 2014 to January 2015 in Liberia and Sierra Leone. Our results suggest that if a combined intervention of case isolation and ring vaccination had been initiated in the early fall of 2014, up to an additional 126 cases in Liberia and 560 cases in Sierra Leone could have been averted beyond case isolation alone. The marginal benefit of ring vaccination is predicted to be greatest in settings where there are more contacts per individual, greater clustering among individuals, when contact tracing has low efficacy or vaccination confers post-exposure protection. In such settings, ring vaccination can avert up to an additional 8% of Ebola cases. Accordingly, ring vaccination is predicted to offer a moderately beneficial supplement to ongoing non-pharmaceutical Ebola control efforts

Retrospective Analysis of the 2014-2015 Ebola Epidemic in Liberia.

The 2014-2015 Ebola epidemic has been the most protracted and devastating in the history of the disease. To prevent future outbreaks on this scale, it is imperative to understand the reasons that led to eventual disease control. Here, we evaluated the shifts of Ebola dynamics at national and local scales during the epidemic in Liberia. We used a transmission model calibrated to epidemiological data between June 9 and December 31, 2014, to estimate the extent of community and hospital transmission. We found that despite varied local epidemic patterns, community transmission was reduced by 40-80% in all the counties analyzed. Our model suggests that the tapering of the epidemic was achieved through reductions in community transmission, rather than accumulation of immune individuals through asymptomatic infection and unreported cases. Although the times at which this transmission reduction occurred in the majority of the Liberian counties started before any large expansion in hospital capacity and the distribution of home protection kits, it remains difficult to associate the presence of interventions with reductions in Ebola incidence

Establishing Ebola Virus Disease (EVD) diagnostics using GeneXpert technology at a mobile laboratory in Liberia: Impact on outbreak response, case management and laboratory systems strengthening.

The 2014-16 Ebola Virus Disease (EVD) outbreak in West Africa highlighted the necessity for readily available, accurate and rapid diagnostics. The magnitude of the outbreak and the re-emergence of clusters of EVD cases following the declaration of interrupted transmission in Liberia, reinforced the need for sustained diagnostics to support surveillance and emergency preparedness. We describe implementation of the Xpert Ebola Assay, a rapid molecular diagnostic test run on the GeneXpert platform, at a mobile laboratory in Liberia and the subsequent impact on EVD outbreak response, case management and laboratory system strengthening. During the period of operation, site coordination, management and operational capacity was supported through a successful collaboration between Ministry of Health (MoH), World Health Organization (WHO) and international partners. A team of Liberian laboratory technicians were trained to conduct EVD diagnostics and the laboratory had capacity to test 64-100 blood specimens per day. Establishment of the laboratory significantly increased the daily testing capacity for EVD in Liberia, from 180 to 250 specimens at a time when the effectiveness of the surveillance system was threatened by insufficient diagnostic capacity. During the 18 months of operation, the laboratory tested a total of 9,063 blood specimens, including 21 EVD positives from six confirmed cases during two outbreaks. Following clearance of the significant backlog of untested EVD specimens in November 2015, a new cluster of EVD cases was detected at the laboratory. Collaboration between surveillance and laboratory coordination teams during this and a later outbreak in March 2016, facilitated timely and targeted response interventions. Specimens taken from cases during both outbreaks were analysed at the laboratory with results informing clinical management of patients and discharge decisions. The GeneXpert platform is easy to use, has relatively low running costs and can be integrated into other national diagnostic algorithms. The technology has on average a 2-hour sample-to-result time and allows for single specimen testing to overcome potential delays of batching. This model of a mobile laboratory equipped with Xpert Ebola test, staffed by local laboratory technicians, could serve to strengthen outbreak preparedness and response for future outbreaks of EVD in Liberia and the region

The prevalence of scabies in Monrovia, Liberia: A population-based survey.

Scabies is known to be a public health problem in many settings but the majority of recent data is from rural settings in the Pacific. There is a need for high quality data from sub-Saharan Africa and peri-urban settings to inform scale up of scabies control efforts. There have been anecdotal reports of scabies being a public health problem in Liberia but robust data are lacking. We conducted a cross-sectional cluster-randomised prevalence survey for scabies in a peri-urban community in Monrovia, Liberia in February-March 2020. Participants underwent a standardised examination conducted by trained local health care workers. Health related quality of life (HRQoL) was assessed using age-appropriate versions of the dermatology life quality index (DLQI). Prevalence estimates were calculated accounting for clustering at community and household levels and associations with key demographic variables assessed through multivariable random-effects logistic regression. 1,318 participants from 477 households were surveyed. The prevalence of scabies was 9.3% (95% CI: 6.5-13.2%), across 75 (19.7%) households; impetigo or infected scabies prevalence was 0.8% (95% CI: 0.4-1.9%). The majority (52%) of scabies cases were classified as severe. Scabies prevalence was lower in females and higher in the youngest age group; no associations were found with other collected demographic or socio-economic variables. DLQI scores indicated a very or extremely large effect on HRQoL in 29% of adults and 18% of children diagnosed with scabies. Our study indicates a substantial burden of scabies in this peri-urban population in Liberia. This was associated with significant impact on quality of life, highlighting the need for action to control scabies in this population. Further work is needed to assess the impact of interventions in this context on both the prevalence of scabies and quality of life

Ring vaccination with rVSV-ZEBOV under expanded access in response to an outbreak of Ebola virus disease in Guinea, 2016: an operational and vaccine safety report.

BACKGROUND: In March, 2016, a flare-up of Ebola virus disease was reported in Guinea, and in response ring vaccination with the unlicensed rVSV-ZEBOV vaccine was introduced under expanded access, the first time that an Ebola vaccine has been used in an outbreak setting outside a clinical trial. Here we describe the safety of rVSV-ZEBOV candidate vaccine and operational feasibility of ring vaccination as a reactive strategy in a resource-limited rural setting. METHODS: Approval for expanded access and compassionate use was rapidly sought and obtained from relevant authorities. Vaccination teams and frozen vaccine were flown to the outbreak settings. Rings of contacts and contacts of contacts were defined and eligible individuals, who had given informed consent, were vaccinated and followed up for 21 days under good clinical practice conditions. FINDINGS: Between March 17 and April 21, 2016, 1510 individuals were vaccinated in four rings in Guinea, including 303 individuals aged between 6 years and 17 years and 307 front-line workers. It took 10 days to vaccinate the first participant following the confirmation of the first case of Ebola virus disease. No secondary cases of Ebola virus disease occurred among the vaccinees. Adverse events following vaccination were reported in 47 (17%) 6-17 year olds (all mild) and 412 (36%) adults (individuals older than 18 years; 98% were mild). Children reported fewer arthralgia events than adults (one [<1%] of 303 children vs 81 [7%] of 1207 adults). No severe vaccine-related adverse events were reported. INTERPRETATION: The results show that a ring vaccination strategy can be rapidly and safely implemented at scale in response to Ebola virus disease outbreaks in rural settings. FUNDING: WHO, Gavi, and the World Food Programme