Myc Dysregulation in Activated Macrophages Initiates Iron-Mediated Lipid Peroxidation that Fuels Type I Interferon and Compromises TB Resistance

A quarter of human population is infected with Mycobacterium tuberculosis, but less than 10% of those infected develop clinical, mostly pulmonary, TB. To dissect mechanisms of susceptibility in immunocompetent individuals, we developed a genetically defined sst1-susceptible mouse model that uniquely reproduces a defining feature of human TB: development of necrotic lung lesions after infection with virulent Mtb. In this study, we explored the connectivity of the sst1-regulated pathways during prolonged macrophage activation with TNF. We determined that the aberrant response of the sst1-susceptible macrophages to TNF was primarily driven by conflicting Myc and antioxidant response pathways that resulted in a coordinated failure to properly sequester intracellular iron and activate ferroptosis inhibitor enzymes. Consequently, iron-mediated lipid peroxidation fueled IFNβ superinduction and sustained the Type I Interferon (IFN-I) pathway hyperactivity that locked the sst1-susceptible macrophages in a state of unresolving stress and compromised their resistance to Mtb. The accumulation of the aberrantly activated, stressed, macrophages within granuloma microenvironment led to the local failure of anti-tuberculosis immunity and tissue necrosis. Our findings suggest a novel link between metabolic dysregulation in macrophages and susceptibility to TB, offering insights into potential therapeutic targets aimed at modulating macrophage function and improving TB control.

Identification of a Novel Interaction between Theileria Prohibitin (TaPHB-1) and Bovine RuvB-Like AAA ATPase 1

Theileriosis is a tick-borne disease caused by Theileria annulata, an intracellular parasite that belongs to the phylum Apicomplexa. The infective forms of the parasite to cattle are sporozoites that are introduced into the host when the infected ticks take a blood meal. The sporozoites selectively invade bovine B cells, macrophages, or monocytes, leading to their cellular transformation. The parasite factors involved in the host cell transformation are not well explored. In pursuit of this, we revisited the probable secretome of the parasite and, following a stringent downscaling criterion, have identified Theileria prohibitin (TaPHB-1) as one of factors secreted into the host cells. Interestingly, in infected cells, TaPHB-1 localized both on the parasite surface and in the host cytoplasm, and independent approaches such as coimmunoprecipitation, yeast two-hybrid screening (Y2H), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) confirmed RuvB-like AAA ATPase 1 (RUVBL-1) as one of its interacting partners. Further, the T. annulata infection does not affect the localization of bovine prohibitin. Mitigating the expression of bovine RUVBL-1 precluded the translocation of TaPHB-1 in the host cell cytoplasm without affecting the host cell viability. Taken together, we report for the first time a unique interaction of TaPHB-1 with bovine RUVBL-1 that is likely needed to cause cancer-like hallmarks during theileriosis. IMPORTANCE Theileria annulata is an apicomplexan parasite that causes tropical theileriosis in cattle. It is the only eukaryotic pathogen able to cause cellular transformation of host cells yielding a cancer-like phenotype. The parasite factors responsible for the transformation of the host cell are largely unknown. This study demonstrates for the first time the partial role of Theileria prohibitin (TaPHB-1) in maintaining the transformed state of the host cell and its interaction with RuvB-like AAA ATPase 1 (RUVBL-1) in a T. annulata-infected bovine cell line. Interestingly, the knockdown of bovine RUVBL-1 rendered the parasites metabolically inactive, implying that the identified interaction is critical for parasite survival. This study contributes to our understanding the Theileria-host interactions and offers scope for novel therapeutic interventions to control theileriosis.

Design of a multi-epitope protein as a subunit vaccine against lumpy skin disease using an immunoinformatics approach

Lumpy skin disease (LSD) is a transboundary viral disease of cattle that causes substantial economic loss globally. There is no specific treatment and subunit vaccine for this disease to date. Reports of the global spread of this disease are worrisome. We designed a multi-epitope protein using an immunoinformatics approach in this study. We analyzed the proteome of LSDV and found 32 structural/surface proteins. Four of these 32 proteins were predicted as antigenic and non-homologous to bovine and highly conserved in 26 LSDV isolates. The predicted B-cell epitopes and CTL epitopes were stitched together with the help of an AAY linker leading to the formation of a multi-epitope protein. The in silico study revealed that the modeled subunit vaccine candidate and TLR4 receptor interact with high affinity. This interaction was also found to be stable using a molecular dynamics simulation study. Our study demonstrates a leap towards developing a subunit vaccine against LSD.

Deciphering the kinome of Theileria annulata for identification of drug targets and anti-theilerial drug

Tropical theileriosis is one of the major parasitic diseases of ruminants. It is a tick-borne disease caused by an apicomplexan parasite, Theileria annulata. In the infected cells, these parasites induce phenotypes similar to cancerous cells. Among the most critical changes induced by the parasite are immortalization, hyperproliferation, and dissemination. The proliferative signal in the T. annulata transformed cells are provided by different kinases such as mitogen-activated protein kinases, SRC family kinases, casein kinase-2, and phosphatidylinositide 3-kinase. Deregulation of protein kinases in cancer is also well known. Targeting protein kinases in a cancerous cell is one of the most common methods in cancer therapy. Here, we revisited the kinome of T. annulata and studied its evolutionary relationship with other piroplasms. This analysis revealed that T. annulata kinome encodes 54 protein kinases. Based on our analysis, 12 of these 54 kinases were identified for the first time in the T. annulata proteome. Three protein kinases, TA16570, TA09820, and TA07000, had <40% identity with Bos taurus and >40% identity with the previously identified potential drug targets present in the Therapeutic Target Database (TTD). These 3 proteins were predicted to be essential for the survival of T. annulata and were selected as drug targets. Screening these drug targets in the Protein Kinase Inhibitor Database (PKID) led to shortlisting of 5 drugs. Only Dabrafenib, out of these 5 drugs, could bind to the ATP binding site (in silico) of the Calcium Dependent Protein Kinase 3 of both T. annulata and Theileria parva. Further, dabrafenib could inhibit the proliferation of T. annulata infected bovine leucocytes in 6 days proliferation assay with the IC50 value of 0.66 µM. Also, this drug did not have a cytotoxic effect on bovine peripheral blood mononuclear cells. In summary, the analysis of T. annulata kinome led to the identification of dabrafenib as a potential drug for treating theileriosis.

MMV560185 from pathogen box induces extrinsic pathway of apoptosis in Theileria annulata infected bovine leucocytes

Tropical theileriosis is a lymphoproliferative disease caused by the intracellular schizonts of Theileria annulata, an apicomplexan parasite. It causes severe infection in cattle and the untreated cattle would possibly die within 3–4 weeks of infection. The chemotherapy for this disease is largely dependent on the use of hydroxynaphthoquinone, namely buparvaquone. There have been reports recently of the development of resistance against this drug in T. annulata. Hence, identification of new drug molecule(s) or repurposing of existing drug molecule(s) against T. annulata is quite important. Here, we present the screening of 400 compounds included in the open-access Pathogen box from Medicine for Malaria Venture (MMV) to discover the novel compounds with potential inhibitory activity against T. annulata infected bovine leucocytes. We identified two compounds, MMV000062 and MMV560185, with IC₅₀ values of 2.97 μM and 3.07 μM, respectively. MMV000062 and MMV560185 were found non-toxic to BoMac cells with CC₅₀ values 34 μM and > 100 μM, respectively. The therapeutic indices of these compounds, MMV000062 and MMV560185, were calculated as more than 33 and 11, respectively. Further, it was observed that the parasite-infected cells under long-term culture were unable to recover with these compounds. We further deciphered that MMV560185 kills the infected cell by activation of TNFR-1 mediated extrinsic pathway of the apoptosis. The phenotypic characteristics of apoptosis were confirmed by Transmission Electron Microscopy. Our results suggest that it may be possible to develop MMV560185 further for chemotherapeutics of tropical theilerosis.

Curcumin induced oxidative stress causes autophagy and apoptosis in bovine leucocytes transformed by Theileria annulata

Bovine tropical theileriosis is a tick-borne disease, caused by Theileria annulata which is a protozoan parasite that resides within the B-cells and macrophages. T. annulata is a unique parasite that can transform bovine leucocytes which leads to the cancer hallmarks in the infected cells. Previously, curcumin has been shown to possess multiple pharmacological activities such as anti-inflammatory and anti-cancer activities. In this study, we demonstrated that curcumin inhibits the proliferation of Theileria-transformed bovine leucocytes by promoting apoptosis and autophagy. The transcriptome analysis of curcumin treated cells showed that the genes involved in cell death and autophagy are also differentially regulated. We further elucidated the mechanism of action of curcumin on Theileria infected bovine cells. We found that curcumin induced the generation of reactive oxygen species (ROS) which activated caspase 8 and destabilized the mitochondrial membrane potential leading to the release of cytochrome c from mitochondria. This subsequently led to the activation of caspase 3 and PARP cleavage, finally leading to apoptosis in the infected cells. Furthermore, curcumin induced the process of autophagy which was characterized by the formation of acidic vesicular organelles, LC3B accumulation with lysosome inhibitor, E64d, and the presence of autophagosomes as visualized by transmission electron microscopy (TEM). Curcumin treatment suppressed the mTOR and increased the expression of autophagy-related proteins. We also found that N- acetylcysteine, an inhibitor of ROS, could rescue the infected cells from curcumin induced apoptosis and autophagy mediated cell death. Intriguingly, curcumin had no effect on uninfected bovine PBMCs. Altogether, these data suggest the therapeutic potential of curcumin against bovine tropical theileriosis.