Biology subjects

Blackburn, J. M.

Publications and source records attributed to Blackburn, J. M..

4 recordsLinked to original sources

bioRxiv2025

A New Serological Autoantibody Signature Associated with Multiple Sclerosis

The role of autoantibodies in the pathogenesis of Multiple Sclerosis (MS) remains incompletely understood. In this study, we analyzed serum samples from a cohort of MS patients in Qatar using high-throughput KoRectly Expressed (KREX) immunome protein-array technology. Compared to healthy controls, MS patients showed significantly altered autoantibody responses to 129 proteins, with a notable enrichment in autoantibodies targeting antiviral immune response-related proteins. Machine learning analysis identified a distinct molecular signature comprising 17 differentially expressed autoantibodies, including those against MX1, ISG20, MAX, SUFU, NR1H2, HMGN5, and EPHA10. Among these, autoantibodies against MX1-a key effector in the interferon-alpha/beta signaling pathway-showed the most pronounced increase, with nearly a threefold elevation in MS patients. While MX1 has previously been implicated in MS, this is the first report of autoantibody reactivity against the protein, suggesting a potential role in disease onset and progression. These findings support a link between antiviral immune responses and MS pathophysiology and offer a promising blood-based autoantibody signature that could inform future diagnostic and therapeutic strategies.

neuroscience↗

bioRxiv2021

The role of copper resistance in Mycobacterium tuberculosis pathogenesis

Despite the development of new drugs and social interventions, tuberculosis remains a leading cause of mortality. This burden falls disproportionately on developing countries, particularly those where the incidence of HIV is high. In the Western Cape, South Africa, we have identified and isolated two Beijing family strains of Mycobacterium tuberculosis that, despite few differences at a genomic level, differ greatly in their severity of disease caused, providing an opportunity to study virulence in this organism. The aim of this study was to identify differences at a genomic and transcriptomic level that may identify the cause of the different virulence levels observed in the two isolates. The isolates were compared at the transcriptome level under four different growth conditions including oxidative stress. In comparing the transcriptome of the two isolates, an operon containing genes involved in the production of molybdenum cofactor that showed consistently lower levels of expression in the hypervirulent isolate was identified. A copper sensing transcriptional regulator was identified as the most probable regulator, and we found that the Cso operon which it is known to regulate was similarly differentially expressed in the strains. The production of molybdenum cofactor is effected in two ways by copper levels. Through the independent insertion of copper into molybdopterin (MPT), and destabilisation of Fe-S clusters. As MoaA3 contains a Fe-S cluster that is known to be destabilised by copper, and a number of copper sensitive genes are likewise found differentially expressed, it is likely that the strains differ in terms of their levels of resistance to copper. It is therefore hypothesised that the differences in virulence are as a result of different levels of resistance to phagosome copper overload, and the mechanism by which copper levels are linked to the production of molybdenum cofactor is described. Author summaryIn this article, we describe the differences in gene expression of two closely related strains of Mycobacterium tuberculosis isolated in the Western Cape of South Africa that differ in the severity of disease that they cause. We compared the strains at a genomic and transcriptomic level, and in doing so, we discovered a set of molybdenum cofactor genes regulated by a copper sensing transcription factor that came up in all datasets. Further genes linked to copper response were identified, providing greater evidence that the difference between the two strains was the manner in which they responded to copper stress. Phagocytes are known to exploit high levels of copper to kill intracellular bacteria, suggesting an important link between copper and disease. We conclude that resistance to copper toxicity is the most probable reason for the relative increase in virulence, and describe the regulatory relationship between copper levels and molybdenum cofactor synthesis.

microbiology↗

bioRxiv2021

Phosphoproteomics reveals new insights into the role of PknG during the persistence of pathogenic mycobacteria in host macrophages

Pathogenic mycobacteria, such as Mycobacterium tuberculosis, modulate the host immune system to evade clearance and promote long-term persistence, resulting in disease progression or latent infection. Understanding the mechanisms pathogenic mycobacteria use to escape elimination by the host immune system is critical to better understanding the molecular mechanisms of mycobacterial infection. Protein kinase G (PknG) in pathogenic mycobacteria has been shown to play an important role in avoiding clearance by macrophages through blocking phagosome-lysosome fusion; however, the exact mechanism is not completely understood. Here, to further investigate the role of mycobacterial PknG during early events of macrophage infection, RAW 264.7 macrophage cell lines were infected with M. bovis BCG wild-type and PknG knock-out mutant strains. After proteolysis, phosphopeptides were enriched via TiO2 columns and subjected to LC-MS/MS to identify differentially phosphorylated peptides between the wild-type and PknG mutant infected macrophages. A total of 1401 phosphosites on 914 unique proteins were identified. Following phosphoproteome normalisation and differential expression analysis, a total of 149 phosphosites were differentially phosphorylated in the wild-type infected RAW 264.7 macrophages versus the PknG knock-out mutant. A subset of 95 phosphosites was differentially up-regulated in the presence of PknG. Functional analysis of our data revealed that PknG kinase activity reprograms normal macrophage function through interfering with host cytoskeletal organisation, spliceosomal machinery, translational initiation, and programmed cell death. Differentially phosphorylated proteins in this study serve as a foundation for further validation and PknG host substrate assignment. ImportanceTuberculosis (TB) remains one of the leading causes of death from infection worldwide, due to the ability of Mycobacterium tuberculosis (Mtb) to survive and replicate within the host, establishing reservoirs of live bacteria that promote persistence and recurrence of disease. Understanding the mechanisms that Mtb uses to evade the host immune system is thus a major goal in the TB field. Protein kinase G is thought to play an important role in Mtb avoiding clearance by the host through disruption of macrophage function, but the underlying molecular mechanisms of this are not well understood. Here, our new phosphoproteomic data reveals that mycobacterial PknG substantially reprograms normal macrophage function through extensive PknG-mediated post-translational control of critical host cellular processes. These novel findings therefore considerably increase our knowledge of mycobacterial pathogenicity, including specific host cellular pathways that might be re-activatable through host-directed therapy, thereby restoring macrophage ability to eliminate Mtb.

molecular biology↗

bioRxiv2020

Microbial function and genital inflammation in young South African women at high risk of HIV infection

BackgroundFemale genital tract (FGT) inflammation is an important risk factor for HIV acquisition. The FGT microbiome is closely associated with inflammatory profile, however, the relative importance of microbial activities has not been established. Since proteins are key elements representing actual microbial functions, this study utilized metaproteomics to evaluate the relationship between FGT microbial function and inflammation in 113 young and adolescent South African women at high risk of HIV infection. Women were grouped as having low, medium or high FGT inflammation by K-means clustering according to pro-inflammatory cytokine concentrations. ResultsA total of 3,186 microbial and human proteins were identified in lateral vaginal wall swabs using liquid chromatography-tandem mass spectrometry, while 94 microbial taxa were included in the taxonomic analysis. Both metaproteomics and 16S rRNA gene sequencing analyses showed increased non-optimal bacteria and decreased lactobacilli in women with FGT inflammatory profiles. However, differences in the predicted relative abundance of most bacteria were observed between 16S rRNA gene sequencing and metaproteomics analyses. Bacterial protein functional annotations (gene ontology) predicted inflammatory cytokine profiles more accurately than bacterial relative abundance determined by 16S rRNA gene sequence analysis, as well as functional predictions based on 16S rRNA gene sequence data (p<0.0001). The majority of microbial biological processes were underrepresented in women with high inflammation compared to those with low inflammation, including a Lactobacillus-associated signature of reduced cell wall organization and peptidoglycan biosynthesis. This signature remained associated with high FGT inflammation in a subset of 74 women nine weeks later, was upheld after adjusting for Lactobacillus relative abundance, and was associated with in vitro inflammatory cytokine responses to Lactobacillus isolates from the same women. Reduced cell wall organization and peptidoglycan biosynthesis were also associated with high FGT inflammation in an independent sample of ten women. ConclusionsBoth the presence of specific microbial taxa in the FGT and their properties and activities are critical determinants of FGT inflammation. Our findings support those of previous studies suggesting that peptidoglycan is directly immunosuppressive, and identify a possible avenue for biotherapeutic development to reduce inflammation in the FGT. To facilitate further investigations of microbial activities, we have developed the FGT-METAP application that is available at (http://immunodb.org/FGTMetap/).

microbiology↗