Editor's note: The interplay between bone marrow stromal cells (BMSCs) and immune as well as hematopoietic functions is a complex yet crucial aspect of maintaining overall health. In this study, researchers delve into the intricate mechanisms underlying this interaction, with a particular focus on the Pinch-Cxcl12-Mbl2 signaling pathway. Through comprehensive analyses using knockout models and BMSCs, we reveal the significance of Pinch proteins in modulating inflammatory diseases and cellular differentiation. Moreover, our investigation highlights the therapeutic potential of recombinant Mbl2 in mitigating immune and hematopoietic dysfunctions. This research sheds light on novel avenues for treating conditions affecting innate immunity and hematopoiesis.Introduction: Mesenchymal stromal cells (MSCs) play a pivotal role in regulating immune responses and maintaining hematopoietic homeostasis within the bone marrow microenvironment. However, the precise mechanisms by which BMSCs exert their effects remain incompletely understood. Previous studies have implicated Pinch proteins in MSC function, prompting further exploration into their role in immune modulation and hematopoiesis. Herein, we present a study aimed at elucidating the influence of the Pinch-Cxcl12-Mbl2 pathway on organ integrity and tissue function, particularly focusing on the cross-talk between bone and liver.
Study Design: The study design was meticulously crafted to comprehensively investigate the influence of Pinch protein deletion in BMSCs on immune and hematopoietic functions. Utilizing a combination of transgenic mouse models, molecular analyses, and therapeutic interventions, our aim was to unravel the intricate interplay between the Pinch-Cxcl12-Mbl2 pathway and organ integrity, particularly focusing on the dynamic communication between bone and liver.
To initiate the investigation, we employed Prx1-Cre; Pinch1 f/f; Pinch2−/− transgenic mice, which allowed for targeted deletion of Pinch1 and Pinch2 proteins specifically in BMSCs. These mice served as the primary experimental group, enabling the assessment of the consequences of Pinch deficiency on immune responses and hematopoiesis. Control groups receiving injections of wild-type BMSCs were included to evaluate the potential rescue of immune and hematopoietic functions.
The experimental timeline encompassed several key stages. Initially, knockout mice and control groups were generated and monitored for signs of immune and hematopoietic dysfunctions. Subsequent analyses involved single-cell RNA sequencing of BMSCs to elucidate cellular alterations resulting from Pinch deletion. This comprehensive approach allowed for a detailed examination of the molecular mechanisms underlying immune modulation and hematopoiesis in the context of Pinch deficiency.
Moreover, to assess the therapeutic potential of recombinant Mbl2 protein in mitigating immune and hematopoietic dysfunctions associated with Pinch deficiency, diseased models were administered with the protein. This intervention aimed to elucidate whether exogenous administration of Mbl2 could effectively restore immune and hematopoietic homeostasis in Pinch-deficient mice, thereby highlighting potential avenues for therapeutic intervention in diseases affecting innate immunity and hematopoiesis.
Methods: The methods employed in this study were carefully chosen to address the research objectives comprehensively and rigorously. Key methodologies included the generation and characterization of Pinch1/2 knockout (dKO) mice, single-cell RNA sequencing of BMSCs, and therapeutic interventions using recombinant Mbl2 protein.
To generate Pinch1/2 dKO mice, we utilized a Cre-loxP system combined with tissue-specific expression of Cre recombinase under the control of the Prx1 promoter. This approach allowed for targeted deletion of Pinch1 and Pinch2 genes specifically in BMSCs while preserving their expression in other tissues. The resulting dKO mice were then subjected to phenotypic characterization to assess the impact of Pinch deficiency on immune and hematopoietic functions.
Subsequently, BMSCs were isolated from Pinch1/2 dKO mice and control groups for single-cell RNA sequencing analysis. This high-resolution technique enabled the identification of transcriptomic alterations in BMSC subpopulations resulting from Pinch deletion, providing valuable insights into the molecular mechanisms underlying immune modulation and hematopoiesis in Pinch-deficient conditions.
Furthermore, to evaluate the therapeutic potential of recombinant Mbl2 protein in rescuing immune and hematopoietic dysfunctions associated with Pinch deficiency, diseased models were administered with the protein. This intervention involved monitoring the health outcomes and survival rates of Pinch-deficient mice following Mbl2 administration, providing critical insights into the efficacy of exogenous Mbl2 in restoring immune and hematopoietic homeostasis.
Results: Mice lacking Pinch1/2 proteins exhibited severe health complications, including subcutaneous hematoma and impaired organ perfusion, leading to premature death. At the cellular level, Pinch deficiency was associated with elevated pro-inflammatory cytokine levels, perturbed bone marrow cellularity, and altered hematopoietic clusters. Remarkably, administration of recombinant Mbl2 protein reversed mortality induced by Pinch loss, highlighting the critical role of the Pinch-Cxcl12-Mbl2 pathway in maintaining survival and homeostasis in mice.
Discussion: Our findings unveil a novel connection between bone-derived signaling proteins and liver function, with profound implications for immune regulation and hematopoiesis. The absence of Pinch disrupts the delicate balance necessary for normal immune and hematopoietic function. Nevertheless, the therapeutic potential of recombinant proteins offers a promising avenue for intervention in diseases where these pathways are compromised. Our results contribute to a deeper understanding of MSCs’ role in immune modulation and pave the way for future clinical applications.
Conclusion and Future Directions: This study elucidates a critical immuno-modulatory pathway involving Pinch-Cxcl12-Mbl2, essential for immune and hematopoietic homeostasis. The therapeutic potential of recombinant Mbl2 protein therapy provides new avenues for addressing immunological and infectious diseases. Future research endeavors will focus on translating these findings to human models and exploring the full therapeutic potential of the signaling pathway.
The groundbreaking study on the Pinch-Cxcl12-Mbl2 signaling pathway was led by a collaborative team of researchers including Tailin He, Bo Zhou, and Guohuan Sun, who contributed equally to the research effort. These scholars are affiliated with esteemed institutions such as the Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China, and The State Key Laboratory of Experimental Hematology, Tianjin, China. The corresponding authors, Xiaochun Bai, Tao Cheng, Huiling Cao, and Guozhi Xiao, played significant roles in this investigation. Xiaochun Bai is associated with the Guangdong Provincial Key Laboratory of Bone and Joint Degeneration Diseases, Southern Medical University, Guangzhou, China, while Tao Cheng is affiliated with the State Key Laboratory of Experimental Hematology, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China. Huiling Cao and Guozhi Xiao are from the Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China. The research findings, published in “Cell Death & Differentiation,” a reputable journal under CDDpress, highlight their collaborative efforts in advancing our understanding of immune and hematopoietic regulation.
