Factors Associated with COVID-19 Vaccine Refusal: A Community-Based Study in the Menoua Division in Cameroon.

COVID-19, which was named in March 2020 as a global pandemic by the WHO, remains a serious public health threat worldwide. Despite the adoption of vaccines as an effective strategy to counter this pandemic, the vaccination rate in Cameroon is far lower than that planned by the Cameroonian government and its partners. The main objective of this study was to determine the factors limiting COVID-19 vaccine acceptance in the Menoua Division in the West Region of Cameroon. A community-based cross-sectional and analytical study was conducted between March and April 2022 in the Menoua Division. A pre-tested questionnaire was filled out by willing participants of more than 18 years old, and data were further expressed in order to estimate the knowledge of participants on COVID-19, vaccine status, and the factors associated with vaccine refusal. A Pearson test was performed in order to identify the associated factors, with a p-value < 0.05 considered as significant. A total of 520 participants with a mean age of 33.27 ± 12.78 were included. Most had a secondary education level (56.15%), and trade and informal sectors (34.04%) were the main occupations. Knowledge on COVID-19 was average, and it was significantly associated (p < 0.05) with gender and education level. The vaccination rate was 10%, which was six times less than the national target. A lack of information, confidence, and medicinal plant use were all factors significantly associated with vaccine refusal. This pioneer community-based study in Cameroon identified a lack of knowledge, confidence, and medicinal plant use as the leading factors limiting COVID-19 vaccine acceptance in Cameroon. Health authorities should therefore strengthen sensitization in order to tackle the lack of information and the misinformation among the target groups.

Effect of microvesicles from Moringa oleifera containing miRNA on proliferation and apoptosis in tumor cell lines.

Human microvesicles are key mediators of cell-cell communication. Exosomes function as microRNA transporters, playing a crucial role in physiological and pathological processes. Plant microvesicles (MVs) display similar features to mammalian exosomes, and these MVs might enhance plant microRNA delivery in mammals. Considering that plant microRNAs have been newly identified as bioactive constituents in medicinal plants, and that their potential role as regulators in mammals has been underlined, in this study, we characterized MVs purified from Moringa oleifera seeds aqueous extract (MOES MVs) and used flow cytometry methods to quantify the ability to deliver their content to host cells. The microRNAs present in MOES MVs were characterized, and through a bioinformatic analysis, specific human apoptosis-related target genes of plant miRNAs were identified. In tumor cell lines, MOES MVs treatment reduced viability, increased apoptosis levels associated with a decrease in B-cell lymphoma 2 protein expression and reduced mitochondrial membrane potential. Interestingly, the effects observed with MOES MVs treatment were comparable to those observed with MOES treatment and transfection with the pool of small RNAs isolated from MOES, used as a control. These results highlight the role of microRNAs transported by MOES MVs as natural bioactive plant compounds that counteract tumorigenesis.

Plant microRNAs from Moringa oleifera Regulate Immune Response and HIV Infection.

Traditional medicine is often chosen due to its affordability, its familiarity with patient's cultural practices, and its wider access to the local community. Plants play an important role in providing indispensable nutrients, while specific small RNAs can regulate human gene expression in a cross-kingdom manner. The aim of the study was to evaluate the effects of plant-enriched purified extract microRNAs from Moringa oleifera seeds (MO) on the immune response and on HIV infection. Bioinformatic analysis shows that plant microRNAs (p-miRs) from MO belonging to 18 conserved families, including p-miR160h, p-miR166, p-miR482b, p-miR159c, p-miR395d, p-miR2118a, p-miR393a, p-miR167f-3p, and p-miR858b are predicted to target with high affinity BCL2, IL2RA, TNF, and VAV1, all these being involved in the cell cycle, apoptosis, immune response and also in the regulation of HIV pathogenesis. The effects of MO p-miRs transfected into HIV+ PBMCs were analyzed and revealed a decrease in viability associated with an increase of apoptosis; an increase of T helper cells expressing Fas and a decrease of intracellular Bcl2 protein expression. Meanwhile no effects were detected in PBMCs from healthy donors. In CD4+ T cells, transfection significantly reduced cell activation and modified the T cell differentiation, thereby decreasing both central and effector memory cells while increasing terminal effector memory cells. Interestingly, the p-miRs transfection induces a reduction of intracellular HIV p24 protein and a reduction of viral DNA integration. Finally, we evaluated the effect of synthetic (mimic) p-miR858b whose sequence is present in the MO p-miR pool and predicted to target VAV1, a protein involved in HIV-Nef binding. This protein plays a pivotal role in T cell antigen receptor (TCR) signaling, so triggering the activation of various pathways. The transfection of HIV+ PBMCs with the synthetic p-miR858b showed a reduced expression of VAV1 and HIV p24 proteins. Overall, our evidence defines putative mechanisms underlying a supplementary benefit of traditional medicine, alongside current antiretroviral therapy, in managing HIV infection in resource-limited settings where MO remains widely available.

Cytotoxic and apoptotic effects of different extracts of Moringa oleifera Lam on lymphoid and monocytoid cells.

Moringa oleifera Lam. (MO) is one of the most well-known and widely distributed species of the Moringaceae family in African communities, and various preparations of M. oleifera are used for the treatment of several diseases. Due to the extensive worldwide use of MO products, and the use of MO aqueous extract in traditional African medicine, the aim of the present study was to investigate the anti-proliferative, cytotoxic and pro-apoptotic activities of different aqueous extracts from leaves and seeds of M. oleifera (MOE), which have been prepared using different protocols, in lymphoid and monocytoid cells. The results of the present study demonstrated the anti-proliferative and pro-apoptotic effects of the aqueous extracts obtained from M. oleifera leaves and seeds on tumour cells; however, not on peripheral blood mononuclear cells (PBMCs) from healthy donors. The pro-apoptotic effect of MO seed aqueous extract (MOE-S) was correlated with decreased B-cell lymphoma 2 (BCL2) and sirtuin-1 (SIRT1) protein expression, which are involved in apoptosis. Considering the effects of plant secondary metabolites on human cells and the role of plant microRNA in cross-kingdom interactions, the presence of secondary metabolites and microRNA in MOE was characterised. In conclusion, M. oleifera aqueous extracts appeared to be able to differentially regulate proliferation and apoptosis in healthy cells and cancer cells, and this ability could be associated with the microRNA present in the extracts. These results highlighted the possible use of MOE as an adjuvant in traditional cancer therapy.

MicroRNA from Moringa oleifera: Identification by High Throughput Sequencing and Their Potential Contribution to Plant Medicinal Value.

Moringa oleifera is a widespread plant with substantial nutritional and medicinal value. We postulated that microRNAs (miRNAs), which are endogenous, noncoding small RNAs regulating gene expression at the post-transcriptional level, might contribute to the medicinal properties of plants of this species after ingestion into human body, regulating human gene expression. However, the knowledge is scarce about miRNA in Moringa. Furthermore, in order to test the hypothesis on the pharmacological potential properties of miRNA, we conducted a high-throughput sequencing analysis using the Illumina platform. A total of 31,290,964 raw reads were produced from a library of small RNA isolated from M. oleifera seeds. We identified 94 conserved and two novel miRNAs that were validated by qRT-PCR assays. Results from qRT-PCR trials conducted on the expression of 20 Moringa miRNA showed that are conserved across multiple plant species as determined by their detection in tissue of other common crop plants. In silico analyses predicted target genes for the conserved miRNA that in turn allowed to relate the miRNAs to the regulation of physiological processes. Some of the predicted plant miRNAs have functional homology to their mammalian counterparts and regulated human genes when they were transfected into cell lines. To our knowledge, this is the first report of discovering M. oleifera miRNAs based on high-throughput sequencing and bioinformatics analysis and we provided new insight into a potential cross-species control of human gene expression. The widespread cultivation and consumption of M. oleifera, for nutritional and medicinal purposes, brings humans into close contact with products and extracts of this plant species. The potential for miRNA transfer should be evaluated as one possible mechanism of action to account for beneficial properties of this valuable species.

Knowledge, attitudes and practices on HIV / AIDS in the south region of Cameroon: case of the town of Kribi.

The aim of our study was to assess knowledge, attitudes, and practices (KAP) regarding HIV/AIDS in the city of Kribi, southern region of Cameroon. In November 2012, a questionnaire composed of 20 items was administered by trained staff from the Biomedical Sciences Department of the University of Dschang to 200 students selected from four population groups: high school students, local traders, tourism personnel (staff of bars, restaurants, hotels, nightclubs), and motorcycle taxi drivers. A cluster sampling method was used to select the first three groups while motorcycle taxi drivers were selected by the method of all comers. KAP regarding HIV/AIDS was found to be fragmentary in the studied population. Only 6.5% systematically uses condoms, 59% believe that AIDS can be cured by traditional medicine and religious faith and 40.9% developed stigmatizing behaviour toward HIV infected people. Among participants there is a wide discrepancy between knowledge and social behaviours toward HIV/AIDS. Strategic and continuous awareness campaigns that are culturally and socially tailored are urgently needed.

Antioxidant and anti-inflammatory activities of extracts from Cassia alata, Eleusine indica, Eremomastax speciosa, Carica papaya and Polyscias fulva medicinal plants collected in Cameroon.

BACKGROUND: The vast majority of the population around the world has always used medicinal plants as first source of health care to fight infectious and non infectious diseases. Most of these medicinal plants may have scientific evidence to be considered in general practice. OBJECTIVE: The aim of this work was to investigate the antioxidant capacities and anti-inflammatory activities of ethanol extracts of leaves of Cassia alata, Eleusine indica, Carica papaya, Eremomastax speciosa and the stem bark of Polyscias fulva, collected in Cameroon. METHODS: Chemiluminescence was used to analyze the antioxidant activities of plant extracts against hydrogen peroxide or superoxide anion. Comet assays were used to analyze the protection against antioxidant-induced DNA damage induced in white blood cells after treating with hydrogen peroxide. Flow cytometry was used to measure γδ T cells proliferation and anti-inflammatory activity of γδ T cells and of immature dendritic cells (imDC) in the presence of different concentrations of plant extracts. RESULTS: Ethanol extracts showed strong antioxidant properties against both hydrogen peroxide and superoxide anion. Cassia alata showed the highest antioxidant activity. The effect of plant extracts on γδ T cells and imDC was evidenced by the dose dependent reduction in TNF-α production in the presence of Cassia alata, Carica papaya, Eremomastax speciosa Eleusine indica, and Polyscias fulva. γδ T cells proliferation was affected to the greatest extent by Polyscias fulva. CONCLUSION: These results clearly show the antioxidant capacity and anti-inflammatory activities of plant extracts collected in Cameroon. These properties of leaves and stem bark extracts may contribute to the value for these plants in traditional medicine and in general medical practice.

Antioxidant extracts of African medicinal plants induce cell cycle arrest and differentiation in B16F10 melanoma cells.

African ethnomedicine is essentially based on the traditional use of vegetal extracts. Since these natural drugs have shown health giving properties, in the present study we increased further the scientific basis supporting these data. We investigated the effects, on murine B16F10 melanoma cells, of plant extracts that were directly obtained by a Cameroon 'traditional healer'. After a preliminary study on the antioxidant functions of these compounds, already abundant in literature, Moringa oleifera Lam., Eremomastax speciosa (Hochst.) Cufod and Aframomum melegueta K. Schum extracts were individually analyzed. We performed laboratory assessments on these medicinal preparations in order to clearly demonstrate their antineoplastic features. All the treatments caused in tumor cells a great reduction in growth and proliferation rate, cell cycle arrest, increase of p53, p21WAF1/Cip1 and p27Kip1 protein levels and induction of differentiation. These results, on the bioactivity and the biochemical characteristics of African plant extracts, may increase the comprehension of indigenous therapeutic practices and represent the first step for the individuation of new inexpensive and natural drugs able to prevent and contrast cancer onset.

Validation of a single-platform, volumetric, flow cytometry for CD4 T cell count monitoring in therapeutic mobile unit.

BACKGROUND: A mobile health unit may be useful to follow up adult and pediatric patients on antiretroviral treatment and living in remote areas devoid of laboratory facilities. The study evaluated the use of the simplified, robust, single-plateform, volumetric, pan-leucogating Auto40 flow cytometer (Apogee Flow Systems Ltd, Hemel Hempstead, UK) for CD4 T cell numeration in a mobile unit, compared against a reference flow cytometry method. METHODS: The therapeutic mobile unit of the Laboratoire National de Santé Hygiène Mobile, Yaoundé, Cameroon, was equipped with the Auto40. A FACSCalibur flow cytometer (Becton Dickinson Immuno-cytometry System, San Jose, CA, USA) was used as reference method. EDTA-blood samples from volunteers were first subjected to CD4 T cell count in the mobile unit, and an aliquot was sent within 4 hours to Centre International de Référence Chantal Biya, Yaoundé, for FACSCalibur assay. RESULTS: Two HIV screening campaigns with the mobile unit were organised in December 2009 and January 2010. The campaign in the suburb of Yaoundé which was 20 km from the reference laboratory included 188 volunteers comprising 93 children less than 5 years old. The campaign in Ambang Bikok (53 km far from Yaoundé) included 69 adult volunteers. In Yaoundé suburb, mean ± standard deviation (SD) CD4 T cell count was 996 ± 874 cells/µl by Auto40, and 989 ± 883 cells/µl by FACSCalibur; in Ambang Bikok, mean ± SD CD4 T cell count was 1041 ± 317 cells/µl by Auto40, and 1032 ± 294 cells/µl by FACSCalibur. Results by Auto40 and FACSCalibur were highly correlated in Yaoundé (r(2) = 0.982) as in Ambang Bikok (r(2) = 0.921). Bland-Altman analysis showed a close agreement between Auto40 and FACSCalibur results expressed in absolute count as in percentage in Yaoundé and Ambang Bikok. When pooling the 257 CD4 T cell count measurements, the Auto40 yielded a mean difference of +7.6 CD4 T cells/µl higher than by reference flow cytometry; and the sensitivity and specificity of Auto40 in enumerating absolute CD4 T cell counts of less than 200 cells/µl were 87% and 99%, respectively, and in enumerating absolute CD4 T cell counts of less than 350 cells/µl were 87% and 98%, respectively. The intrarun and interun precisions of the Auto40 assay assessed in the mobile unit were 5.5% and 7.9%, respectively. CONCLUSIONS: The Auto40 flow cytometer installed in a therapeutic mobile unit and operated far from its reference laboratory gave a perfect correlation with the reference method, and could be useful in carrying out immunological monitoring of HIV-infected patients living in areas without access to laboratory facilities.