Low plasma haptoglobin is a risk factor for life-threatening childhood severe malarial anemia and not an exclusive consequence of hemolysis

An immuno-inflammatory profiling of asymptomatic individuals in a malaria endemic area in Uganda

Malaria caused by Plasmodium falciparum leads to the destruction of red blood cells (RBCs). A better understanding of how naturally immune individuals control infections should be valuable for future vaccine studies. Antibodies against RBCs and RBC surface antigens were measured together with different inflammatory markers in healthy adults living in a malaria endemic area of Uganda and compared to Swedish healthy adults. Antibodies binding to RBCs were clearly elevated in Ugandans compared to Swedish samples, and for RBC surface antigens the Ugandans had higher levels of antibodies against JMH, but not against Cromer or Kell. Twenty-eight percent of the Ugandans were PCR-positive for P. falciparum, and these had higher levels of IgG against parasite extract and more inhibition in functional growth/invasion assays, but levels of antibodies against RBC, RBC surface antigens, results from Direct Antiglobulin Tests (DAT) and indirect antiglobulin tests were similar when compared with PCR-negative individuals. When inflammatory markers (α-1-antitrypsin, haptoglobin, orosomucoid/α-1-acid glycoprotein, CRP, IgG, IgA and IgM) were measured there were in general almost no signs of inflammation except for clearly elevated levels of IgG. Some had low levels of haptoglobin and for orosomucoid more than half of the individuals had clearly reduced levels. There was no correlation between the inflammatory markers and PCR-positivity, antibodies against RBCs or parasites. In conclusion, for healthy adults living in a malaria endemic area, there was a clear presence of antibodies against RBCs in parallel with high levels of IgG and almost no signs of inflammation, even though many individuals were carrying parasites.

Involvement of haptoglobin in disease development

Haptoglobin (HP) is a liver glycoprotein that is actively synthesized during inflammatory and hemolytic processes. It also has pro-oxidant and proinflammatory properties, which are a function of its genotype. The genetic polymorphism of the chains leads to synthesis of three phenotypes/proteins, which are related to the number and type of chains and their molecular weight, namely HP1-1, HP1-2 and HP2-2. Patients with HP2-2 have more vascular complications, while those with HP1-1 have fewer. HP is involved in the worsening of diseases, such as HP2-2 in aggravation of vaso-occlusive crises in sickle cell disease, and worsening of the pathophysiology of other diseases. In contrast, HP1-1 confers better protection against diseases. All of this suggests that further studies should be conducted, including experimental and analytical studies focused on demonstrating the influence of different HP genotypes on individual clinical and hematological data. This would help in understanding the role played by this genetic polymorphism in the pathophysiology of diseases.

Haptoglobin gene polymorphism and iron profile in sickle cell disease patients with inflammation in Yaounde, Cameroon

Background

Major sickle cell syndromes are the most common hemoglobinopathy in the world. The sickle cell patients are subjected to several factors causing inflammation, and the genetic identification of each individual allows to focus the possibility of allelic variations influence of a specific gene and then the polymorphism. This study aims at determining the distribution of HP gene (OMIM#140100) and their involvement on hematological parameters and the iron profile in the sickle cell patients presenting an inflammation condition during major sickle cell syndromes in Cameroun.

Methods

A case–control analytical study has been conducted over a period of 6 months. Cases consisting of sickle cell patients in a situation of inflammation and control of non‐inflamed sickle cell patients. The patients presenting major sickle cell syndromes, interned and/or followed at the Hematology Department of the Regional Hospital of Bafoussam and the Central Hospital of Yaoundé have been recruited. HP genotyping was carried out at the Laboratory for Public Health Research Biotechnologies (LAPHER‐Biotech) in Yaoundé using allele‐specific PCR. Also, inflammatory, hematological parameters and martial assessment were explored by standard methods. Statistical analysis of the data was performed using the statistical tool R version 4.1.1. The comparison of proportions of alleles was made with the chi‐square test, and the Wilcoxon test was used to compare the median between different groups using the statistical tool R version 4.1.1.

Results

We analyzed the samples of 149 patients. The HP polymorphism describes a significant frequency of the “1F” allele (69.8%) followed by the “2” allele (46.31%). In addition, 80 patients (53.69%), 48 (32.21%), and 21 (14.09%) presented the genotype HP 1‐1, HP 2‐1, and HP 2‐2, respectively. And eighty‐one percent (81%) patients with genotype HP 2‐2 showed a significant higher relative frequency of thrombocytosis compared with the genotype HP 1‐1 and HP 2‐1, respectively (51.2% and 68.8%, p = 0.087). The proportion of inflammation in the HP 2‐2 group was higher (57.1%) compared with the other groups (respectively 42.5% and 35.4% in the HP 1‐1 and HP 2‐1 groups). Furthermore, the median CRP was significantly higher in the HP 2‐2 group compared with the other groups (p = 0.039). Moreover, the entire population of the HP 2‐2 group showed an elevation of ferritin and IL6 unlike the HP 1‐1 and HP 2‐1 groups.

Conclusion

This study demonstrates a higher frequency of genotype HP 1‐1 followed by the HP 2‐2 genotype in patients with major sickle cell syndromes. However, a larger proportion of patients with genotype HP 2‐2 are associated with hematological profile disorders, inflammation, and dysregulation of iron metabolism. Then, the haptoglobin polymorphism contributes to the severity of major sickle cell syndromes.

Homozygote drepanocytosis: Ferric status and inflammation in world and Africa: Review article and meta analysis

BACKGROUND AND AIMS

Major sickle cell syndromes are subjected to a high frequency of hemolysis, infections, oxidative stress, and vasooclusive crises which promote inflammation and iron balance disorders. We aimed to systematically review and analyze the studies in this patients addressing in general, and Africa in particular.

METHODS

The systematic review of published articles in the Pubmed and Google Scholar databases was carried out according to the recommendations of the PRISMA model. The case-control articles have been included. The data extracted from the articles were analyzed using statistical software R. The standardized mean difference (SMD) was used to assess the extent of the disease on the different variables studied.

RESULTS

At the end, 128 articles were obtained; but only 33 were elligible for meta-analysis. A SMD of -1.79 was obtained for hemoglobin between the sickle cell patients and the controls due to the deviation from the overall mean hemoglobin in the cases (8 ± 2 g/dL) and in controls (13 ± 3 g/dL). Sickle cell disease showed a significant extent on ferritin [SMD = 2.61; (95% confidence interval, CI: 2.39-2.83); (p < 0.01)] compared to non-sickle cell patients thus describing a higher risk for sickle cell sufferer to have ferritin disorders. The included studies also described the influence of sickle cell anemia on serum iron [SMD = 1.52; (95% CI: 1.32-1.76); (p < 0.01)] compared to normal subjects. The high risk of inflammation has been described as higher in sickle cell patients [SMD = 0.38; (95% CI: 0.25-0.50)], reflecting the moderate extent of sickle cell disease on inflammation.

CONCLUSION

Patients with major sickle cell syndrome in inflammation have a higher risk of iron profile disorders compared to the normal population. Further studies are needed to explore mechanisms for preventing the deleterious effects of iron from this hemolysis, for example haptoglobin genotyping.

Anti-phosphatidylserine antibody levels are low in multigravid pregnant women in a malaria-endemic area in Nigeria, and do not correlate with anti-VAR2CSA antibodies

Anemia is a common malaria-associated complication in pregnant women in endemic regions. Phosphatidylserine (PS) is exposed to the immune system during the massive destruction of red blood cells (RBCs) that accompany malaria, and antibodies against PS have been linked to anemia through destruction of uninfected RBCs. We determined levels of anti-PS IgG antibodies in pregnant women in Ibadan, Nigeria and correlated them to parameters of importance in development of anemia and immunity. Anti-PS correlated inversely with Packed Cell Volume (PCV), indicating that the antibodies could contribute to anemia. There was no correlation with anti-VAR2CSA IgG, haptoglobin or parasitemia, indicating that the modulation of anti-PS response is multifactorial in nature. Anti-PS levels were lowest in multigravidae compared to both primigravidae and secundigravidae and correlated inversely with age. In conclusion, lower levels of anti-PS in multigravidae could be beneficial in avoiding anemia.

piRNA-like small RNAs target transposable elements in a Clade IV parasitic nematode

The small RNA (sRNA) pathways identified in the model organism Caenorhabditis elegans are not widely conserved across nematodes. For example, the PIWI pathway and PIWI-interacting RNAs (piRNAs) are involved in regulating and silencing transposable elements (TE) in most animals but have been lost in nematodes outside of the C. elegans group (Clade V), and little is known about how nematodes regulate TEs in the absence of the PIWI pathway. Here, we investigated the role of sRNAs in the Clade IV parasitic nematode Strongyloides ratti by comparing two genetically identical adult stages (the parasitic female and free-living female). We identified putative small-interfering RNAs, microRNAs and tRNA-derived sRNA fragments that are differentially expressed between the two adult stages. Two classes of sRNAs were predicted to regulate TE activity including (i) a parasite-associated class of 21-22 nt long sRNAs with a 5' uridine (21-22Us) and a 5' monophosphate, and (ii) 27 nt long sRNAs with a 5' guanine/adenine (27GAs) and a 5' modification. The 21-22Us show striking resemblance to the 21U PIWI-interacting RNAs found in C. elegans, including an AT rich upstream sequence, overlapping loci and physical clustering in the genome. Overall, we have shown that an alternative class of sRNAs compensate for the loss of piRNAs and regulate TE activity in nematodes outside of Clade V.

Forward Genetics in Apicomplexa Biology: The Host Side of the Story

Forward genetic approaches have been widely used in parasitology and have proven their power to reveal the complexities of host-parasite interactions in an unbiased fashion. Many aspects of the parasite's biology, including the identification of virulence factors, replication determinants, antibiotic resistance genes, and other factors required for parasitic life, have been discovered using such strategies. Forward genetic approaches have also been employed to understand host resistance mechanisms to parasitic infection. Here, we will introduce and review all forward genetic approaches that have been used to identify host factors involved with Apicomplexa infections, which include classical genetic screens and QTL mapping, GWAS, ENU mutagenesis, overexpression, RNAi and CRISPR-Cas9 library screens. Collectively, these screens have improved our understanding of host resistance mechanisms, immune regulation, vaccine and drug designs for Apicomplexa parasites. We will also discuss how recent advances in molecular genetics give present opportunities to further explore host-parasite relationships.

Data-driven malaria prevalence prediction in large densely populated urban holoendemic sub-Saharan West Africa

Over 200 million malaria cases globally lead to half-million deaths annually. The development of malaria prevalence prediction systems to support malaria care pathways has been hindered by lack of data, a tendency towards universal "monolithic" models (one-size-fits-all-regions) and a focus on long lead time predictions. Current systems do not provide short-term local predictions at an accuracy suitable for deployment in clinical practice. Here we show a data-driven approach that reliably produces one-month-ahead prevalence prediction within a densely populated all-year-round malaria metropolis of over 3.5 million inhabitants situated in Nigeria which has one of the largest global burdens of P. falciparum malaria. We estimate one-month-ahead prevalence in a unique 22-years prospective regional dataset of > 9 × 10⁴ participants attending our healthcare services. Our system agrees with both magnitude and direction of the prediction on validation data achieving MAE ≤ 6 × 10^-2, MSE ≤ 7 × 10^-3, PCC (median 0.63, IQR 0.3) and with more than 80% of estimates within a (+ 0.1 to - 0.05) error-tolerance range which is clinically relevant for decision-support in our holoendemic setting. Our data-driven approach could facilitate healthcare systems to harness their own data to support local malaria care pathways.

Expert-level automated malaria diagnosis on routine blood films with deep neural networks

Over 200 million malaria cases globally lead to half a million deaths annually. Accurate malaria diagnosis remains a challenge. Automated imaging processing approaches to analyze Thick Blood Films (TBF) could provide scalable solutions, for urban healthcare providers in the holoendemic malaria sub-Saharan region. Although several approaches have been attempted to identify malaria parasites in TBF, none have achieved negative and positive predictive performance suitable for clinical use in the west sub-Saharan region. While malaria parasite object detection remains an intermediary step in achieving automatic patient diagnosis, training state-of-the-art deep-learning object detectors requires the human-expert labor-intensive process of labeling a large dataset of digitized TBF. To overcome these challenges and to achieve a clinically usable system, we show a novel approach. It leverages routine clinical-microscopy labels from our quality-controlled malaria clinics, to train a Deep Malaria Convolutional Neural Network classifier (DeepMCNN) for automated malaria diagnosis. Our system also provides total Malaria Parasite (MP) and White Blood Cell (WBC) counts allowing parasitemia estimation in MP/μL, as recommended by the WHO. Prospective validation of the DeepMCNN achieves sensitivity/specificity of 0.92/0.90 against expert-level malaria diagnosis. Our approach PPV/NPV performance is of 0.92/0.90, which is clinically usable in our holoendemic settings in the densely populated metropolis of Ibadan. It is located within the most populous African country (Nigeria) and with one of the largest burdens of Plasmodium falciparum malaria. Our openly available method is of importance for strategies aimed to scale malaria diagnosis in urban regions where daily assessment of thousands of specimens is required.

Haptoglobin: From hemoglobin scavenging to human health

Haptoglobin (Hp) belongs to the family of acute-phase plasma proteins and represents the most important plasma detoxifier of hemoglobin (Hb). The basic Hp molecule is a tetrameric protein built by two α/β dimers. Each Hp α/β dimer is encoded by a single gene and is synthesized as a single polypeptide. Following post-translational protease-dependent cleavage of the Hp polypeptide, the α and β chains are linked by disulfide bridge(s) to generate the mature Hp protein. As human Hp gene is characterized by two common Hp1 and Hp2 alleles, three major genotypes can result (i.e., Hp1-1, Hp2-1, and Hp2-2). Hp regulates Hb clearance from circulation by the macrophage-specific receptor CD163, thus preventing Hb-mediated severe consequences for health. Indeed, the antioxidant and Hb binding properties of Hp as well as its ability to stimulate cells of the monocyte/macrophage lineage and to modulate the helper T-cell type 1 and type 2 balance significantly associate with a variety of pathogenic disorders (e.g., infectious diseases, diabetes, cardiovascular diseases, and cancer). Alternative functions of the variants Hp1 and Hp2 have been reported, particularly in the susceptibility and protection against infectious (e.g., pulmonary tuberculosis, HIV, and malaria) and non-infectious (e.g., diabetes, cardiovascular diseases and obesity) diseases. Both high and low levels of Hp are indicative of clinical conditions: Hp plasma levels increase during infections, inflammation, and various malignant diseases, and decrease during malnutrition, hemolysis, hepatic disease, allergic reactions, and seizure disorders. Of note, the Hp:Hb complexes display heme-based reactivity; in fact, they bind several ferrous and ferric ligands, including O₂, CO, and NO, and display (pseudo-)enzymatic properties (e.g., NO and peroxynitrite detoxification). Here, genetic, biochemical, biomedical, and biotechnological aspects of Hp are reviewed.

Depleted circulatory complement-lysis inhibitor (CLI) in childhood cerebral malaria returns to normal with convalescence

BACKGROUND

Cerebral malaria (CM), is a life-threatening childhood malaria syndrome with high mortality. CM is associated with impaired consciousness and neurological damage. It is not fully understood, as yet, why some children develop CM. Presented here is an observation from longitudinal studies on CM in a paediatric cohort of children from a large, densely-populated and malaria holoendemic, sub-Saharan, West African metropolis.

METHODS

Plasma samples were collected from a cohort of children with CM, severe malarial anaemia (SMA), uncomplicated malaria (UM), non-malaria positive healthy community controls (CC), and coma and anemic patients without malaria, as disease controls (DC). Proteomic two-dimensional difference gel electrophoresis (2D-DIGE) and mass spectrometry were used in a discovery cohort to identify plasma proteins that might be discriminatory among these clinical groups. The circulatory levels of identified proteins of interest were quantified by ELISA in a prospective validation cohort.

RESULTS

The proteome analysis revealed differential abundance of circulatory complement-lysis inhibitor (CLI), also known as Clusterin (CLU). CLI circulatory level was low at hospital admission in all children presenting with CM and recovered to normal level during convalescence (p < 0.0001). At acute onset, circulatory level of CLI in the CM group significantly discriminates CM from the UM, SMA, DC and CC groups.

CONCLUSIONS

The CLI circulatory level is low in all patients in the CM group at admission, but recovers through convalescence. The level of CLI at acute onset may be a specific discriminatory marker of CM. This work suggests that CLI may play a role in the pathophysiology of CM and may be useful in the diagnosis and follow-up of children presenting with CM.