Clonal hematopoiesis driven by mutated DNMT3A promotes inflammatory bone loss.

Clonal hematopoiesis of indeterminate potential (CHIP) arises from aging-associated acquired mutations in hematopoietic progenitors, which display clonal expansion and produce phenotypically altered leukocytes. We associated CHIP-DNMT3A mutations with a higher prevalence of periodontitis and gingival inflammation among 4,946 community-dwelling adults. To model DNMT3A-driven CHIP, we used mice with the heterozygous loss-of-function mutation R878H, equivalent to the human hotspot mutation R882H. Partial transplantation with Dnmt3aR878H/+ bone marrow (BM) cells resulted in clonal expansion of mutant cells into both myeloid and lymphoid lineages and an elevated abundance of osteoclast precursors in the BM and osteoclastogenic macrophages in the periphery. DNMT3A-driven clonal hematopoiesis in recipient mice promoted naturally occurring periodontitis and aggravated experimentally induced periodontitis and arthritis, associated with enhanced osteoclastogenesis, IL-17-dependent inflammation and neutrophil responses, and impaired regulatory T cell immunosuppressive activity. DNMT3A-driven clonal hematopoiesis and, subsequently, periodontitis were suppressed by rapamycin treatment. DNMT3A-driven CHIP represents a treatable state of maladaptive hematopoiesis promoting inflammatory bone loss.

In Vitro Assay for the Assessment of Oxygen Depletion Triggers in Human Cell Lines, Associated with Improving Responses to Cancer Therapy.

Tumors are usually associated with oxygen-deficient regions (hypoxia) which results from reduced and disorganized intratumoral vasculature, increased diffusion distances, and growing tumor masses. The proteomic and metabolomic landscape of the hypoxic cells is reprogrammed through hypoxia-induced transcription factor 1 which is activated in hypoxic conditions and is inactive when oxygen is abundant. This transcription factor has also been shown to inhibit or even reverse cell differentiation. Hypoxia impedes chemotherapy as it hampers the formation of cytotoxic free radicals due to the lesser availability of molecular oxygen. The metastatic and invasive attributes of cancer cells in hypoxic conditions are exacerbated, which results in poor therapeutic outcomes. Various cell-based assays for measuring hypoxia have been developed which give an estimate of the hypoxic state of cancer cells. Prior knowledge of these assays will improve the efficacy of the treatment regimens for cancers. This article provides exhaustive information on the hypoxia-based assays which are sensitive, robust, reliable, and give easy readout with choice of cell type for these assays may be dictated by the procedural or endpoint selection.

Maladaptive innate immune training of myelopoiesis links inflammatory comorbidities.

Bone marrow (BM)-mediated trained innate immunity (TII) is a state of heightened immune responsiveness of hematopoietic stem and progenitor cells (HSPC) and their myeloid progeny. We show here that maladaptive BM-mediated TII underlies inflammatory comorbidities, as exemplified by the periodontitis-arthritis axis. Experimental-periodontitis-related systemic inflammation in mice induced epigenetic rewiring of HSPC and led to sustained enhancement of production of myeloid cells with increased inflammatory preparedness. The periodontitis-induced trained phenotype was transmissible by BM transplantation to naive recipients, which exhibited increased inflammatory responsiveness and disease severity when subjected to inflammatory arthritis. IL-1 signaling in HSPC was essential for their maladaptive training by periodontitis. Therefore, maladaptive innate immune training of myelopoiesis underlies inflammatory comorbidities and may be pharmacologically targeted to treat them via a holistic approach.

BLIMP-1 Mediated Downregulation of TAK1 and p53 Molecules Is Crucial in the Pathogenesis of Kala-Azar.

Precise regulation of inflammasome is critical during any pathogenic encounter. The whole innate immune system comprising of pattern recognition receptors (PRRs) relies on its ability to sense microbes. The fate of cellular death in infected cells depends mostly on the activation of these inflammasome, the dysregulation of which, due to functional manipulation by various pathogens, leads to be the cause of many human diseases. Here, an interesting finding has been observed which is related to how Leishmania donovani parasites exploit various host mediator molecules to cause immunosuppression. Here we report for the first time that the parasites check pyroptosis in the infected cells in-vitro by BLIMP-1 mediated suppression of TAK1 and p53 proteins. This might be one of the reasons how parasites evade the pro-inflammatory response of the host cells. Further understandings and validations are required to come up with better therapeutic approaches against kala-azar.

BLIMP-1 Plays Important Role in the Regulation of Macrophage Pyroptosis for the Growth and Multiplication of Leishmania donovani.

Visceral leishmaniasis, one of the fatal forms of the disease, is caused by Leishmania donovani and presents morbid clinical manifestations. The parasite evades pro-inflammatory immune responses by several reported mechanisms and modulates the host immune system to cause fatal symptoms. A plethora of reports related to the role of BLIMP-1 and its involvement in suppressing the immune response in various infectious diseases have been documented. Higher parasitic burden due to increased BLIMP-1 production has been reported earlier for malaria and leishmaniasis with no detailed information. We report for the first time the role of BLIMP-1 in suppressing macrophage pyroptosis during L. donovani infection and thereby tweaking the tight regulation of the NFκß-NLRP3 signaling pathway. Expression analyses of BLIMP-1 and NFκß have been measured using real-time PCR and Western blotting. The importance of BLIMP-1 has been validated using a siRNA-mediated experiment along with caspase 1 activity, LDH release assay, and infectivity index analyses. An inverse relationship between BLIMP-1 and NFκß expression has been highlighted during L. donovani infection, which is reversed in blimp-1 deficient cells infected with promastigotes. The above fact has been further validated with caspase 1 activity assay, and LDH release along with IFNγ and TNF-α release assay. Finally, resumption of pyroptosis has been concluded in infected blimp-1 deficient cells in contrast to wild type infected cells. We conjecture that parasites modulate the NFκß-NLRP3 signaling pathway by taking advantage of BLIMP-1 dependent IL-10 production and finally disrupting an inflammation-mediated pyroptosis cell death pathway in infected cells.

Apoptosis: Mediator Molecules, Interplay with Other Cell Death Processes and Therapeutic Potentials.

Apoptosis, a form of programmed cell death, plays a very crucial role in various physiological processes for maintaining cell homeostasis. This process has several characteristic features like membrane blebbing, nuclear condensation, DNA fragmentation and cell shrinkage. Any defect in this highly regulated process eventually leads to extended cell survival and could result in neoplastic cell expansion followed by genetic instability. The apoptotic machinery is mainly processed and regulated by various caspases, a family of cysteine proteases. Significant advancement has been made towards understanding the molecular mechanisms of apoptosis which provides new insights in modulating the life or death of a cell. The main goal of this review is to highlight recent updates on apoptosis, the cross-talk with other cellular death processes and its therapeutic potentials.

Novel Agents against Miltefosine-Unresponsive Leishmania donovani.

Visceral leishmaniasis is a deadly endemic disease. Unresponsiveness to the only available oral drug miltefosine poses a big challenge for the chemotherapy of the disease. We report a novel molecule, PS-203 {4-(4,4,8-trimethyl-7-oxo-3-oxabicyclo[3.3.1]non-2-yl)-benzoic acid methyl ester}, as effective against a miltefosine-unresponsive strain of the parasite. Further, combinations of PS-203 with miltefosine were also evaluated and showed promising results against a miltefosine-unresponsive strain.