Plant Growth Promoting Rhizobacteria (PGPR) induced protection: A plant immunity perspective.

Plant-environment interactions, particularly biotic stress, are increasingly essential for global food security due to crop losses in the dynamic environment. Therefore, understanding plant responses to biotic stress is vital to mitigate damage. Beneficial microorganisms and their association with plants can reduce the damage associated with plant pathogens. One such group is PGPR (Plant growth-promoting rhizobacteria), which influences plant immunity significantly by interacting with biotic stress factors and plant signalling compounds. This review explores the types, metabolism, and mechanisms of action of PGPR, including their enzyme pathways and the signalling compounds secreted by PGPR that modulate gene and protein expression during plant defence. Furthermore, the review will delve into the crosstalk between PGPR and other plant growth regulators and signalling compounds, elucidating the physiological, biochemical, and molecular insights into PGPR's impact on plants under multiple biotic stresses, including interactions with fungi, bacteria, and viruses. Overall, the review comprehensively adds to our knowledge about PGPR's role in plant immunity and its application for agricultural resilience and food security.

Morphological and biochemical responses of Vicia faba (faba beans) grown on fly ash amended soil in the presence of Rhizobium leguminosarum and arbuscular mycorrhizal fungus.

An experiment was conducted in the greenhouse to investigate the feasibility of Vicia faba grown on different fly ash concentrations (0-30%) and dual inoculation with Rhizobium and arbuscular mycorrhizal fungi (AMF). Sampling was done 45 days after sowing to analyse the plant growth parameters, photosynthetic attributes (total chlorophyll and carotenoids content), protein content, nitrogen (N) and phosphorus (P) content, defensive factors (antioxidant activity and proline content) and damage markers (lipid peroxidation, reactive oxygen species and cell viability). The results revealed that the application of fly ash (FA) alone did not result in any significant improvement in growth, biochemical and physiological parameters. However, dual inoculation showed a synergistic impact on legume growth, photosynthetic pigments, protein, proline, and cell viability. Rhizobium, AMF and 10% FA showed maximum enhancement in all attributes mentioned. 20% and 30% fly doses showed a reduction in growth, photosynthesis and antioxidants and caused oxidative stress via lipid peroxidation. The results showed that the synergistic or combined interactions between all three variables of the symbiotic relationship (Rhizobium-legume-AMF) boosted plant productivity.

T-cell signature cytokines distinguish pulmonary sarcoidosis from pulmonary tuberculosis.

Sarcoidosis is a systemic inflammatory disorder characterized by tissue infiltration due to mononuclear phagocytes and lymphocytes and associated noncaseating granuloma formation. Pulmonary sarcoidosis (PS) shares a number of clinical, radiological, and histopathological characteristics with that of pulmonary tuberculosis (PTB). Due to this, clinicians face issues in differentiating between PS and PTB in a substantial number of cases. There is a lack of any specific biomarker that can diagnose PS distinctively from PTB. We compared T-cell-based signature cytokines in patients with PS and PTB. In this study, we proposed a serum biomarker panel consisting of cytokines from cells: T helper (Th) 1 [interferon-gamma (IFN-γ); tumor necrosis factor-alpha (TNF-α)], Th9 [interleukin (IL)-9], Th17 [IL-17], and T regulatory (Treg) [IL-10; transforming growth factor-beta (TGF-ß)]. We performed the principal component analysis that demonstrated that our serum cytokine panel has a significant predictive ability to differentiate PS from PTB. Our results could aid clinicians to improve the diagnostic workflow for patients with PS in TB endemic settings where the diagnosis between PS and PTB is often ambiguous.

Interleukin-9 rescues class switching of Memory B cells derived from Common variable immunodeficiency patients.

Impaired class switch memory (CSM) B cell formation is the hallmark of common variable immunodeficiency (CVID). Various T cell abnormalities have been observed in CVID patients indicating inadequate T-cell help to B cells. A major setback in understanding its pathogenesis is due to diverse clinical presentation. Therefore, we performed extensive immunological investigation in a cohort of CVID patients with similar clinical findings in order to unravel the T cell dysfunction and its influence on the defective humoral immune response. All recruited CVID patients exhibited B cells in the normal range, but reduced CSM B cells. However, patients showed reduced T cell proliferation, reduced level of serum Interleukin-9 (IL-9) and frequency of IL-9 expressing CD4 (Th-9) cells. IL-9 supplementation along with CD40 engagement was effective in inducing in vitro CSM B cells formation in CVID patients. Thus, IL-9 supplementation has the potential to restore impaired CSM B cell formation in CVID.

Butyrophilins: Dynamic Regulators of Protective T Cell Immunity in Cancer.

The efficacy of current immunotherapies remains limited in many solid epithelial malignancies. Recent investigations into the biology of butyrophilin (BTN) and butyrophilin-like (BTNL) molecules, however, suggest these molecules are potent immunosuppressors of antigen-specific protective T cell activity in tumor beds. BTN and BTNL molecules also associate with each other dynamically on cellular surfaces in specific contexts, which modulates their biology. At least in the case of BTN3A1, this dynamism drives the immunosuppression of αß T cells or the activation of Vγ9Vδ2 T cells. Clearly, there is much to learn regarding the biology of BTN and BTNL molecules in the context of cancer, where they may represent intriguing immunotherapeutic targets that could potentially synergize with the current class of immune modulators in cancer. Here, we discuss our current understanding of BTN and BTNL biology, with a particular focus on BTN3A1, and potential therapeutic implications for cancer.

Inhibiting OX40 Restores Regulatory T-Cell Function and Suppresses Inflammation in Pulmonary Sarcoidosis.

BACKGROUND: Pulmonary sarcoidosis (PS) is a noncaseating granulomatous disease of unknown origin. Despite conflicting reports, it is considered that the regulatory T (Treg) cells are functionally impaired in PS, but the underlying mechanisms remain unclear. OX40, a pivotal costimulatory molecule, is essential for T-cell functions and memory development, but its impact on Treg cells is ambiguous. RESEARCH QUESTION: Does the OX40 pathway influence the suppressive functions of Treg cells in PS? STUDY DESIGN AND METHODS: Fifty treatment-naïve patients with PS and 30 healthy control participants were recruited for this study. Polychromatic flow cytometry-based immunologic assays were performed to enumerate effector T helper (Th) cells and Treg cells along with their functions. Using real-time polymerase chain reaction analysis, small interfering RNA, and pharmacologic inhibitors, the impact of OX40 on Treg cell function was investigated. RESULTS: We observed enrichment of Th-9 cells perhaps for the first time along with Th-1, Th-17, and Treg cells in patients' BAL fluid (BALF) compared with peripheral blood. However, Treg cells were observed to be functionally defective at the pathological site. We observed higher expression of OX40 on both T effector (CD4+Foxp3-) and Treg (CD4+Foxp3+) cells obtained from the BALF of patients with PS. However, OX40 exerted contrasting impact on these T-cell subsets, enhancing effector T-cell functions (interferon γ, tumor necrosis factor α) while inhibiting Treg cell function (IL-10, transforming growth factor ß). OX40 silencing or blocking on Treg cells resulted in restoration of their impaired functions. INTERPRETATION: We propose that inhibiting the OX40 pathway may constitute a therapeutic strategy for controlling inflammatory T cells by restoring Treg cell functions in patients with PS.

Primary Immunodeficiency Disorders Among North Indian Children.

OBJECTIVES: To report the distribution pattern of various categories of primary immunodeficiency disorders (PIDs) in children from North India, frequency of warning signs and critical parameters for evaluation. METHODS: In this retrospective study, 528 children below 18 y of age after clinical assessment and presentation suggestive of PID were further screened by immunophenotyping for immune cell markers by flow cytometry. RESULTS: A total of 120 (23%) children were diagnosed with PID with median age at diagnosis being 2.5 y in males and 3.5 y in females and an average delay in diagnosis from onset of symptoms being approximately 5 y. Chronic lower respiratory tract infections, gastrointestinal symptoms like persistent diarrhea and failure to thrive were amongst the most common warning signs in these patients. PIDs were classified according to the International Union of Immunological Societies' (IUIS) criteria. The diagnosis of index study subjects included combined humoral and cellular immunodeficiency (29%), phagocytic defects (29%), followed by predominantly antibody deficiency (18%), innate immunity and dysregulation (17%) and other well-defined syndromes (7%). A family history of PID (23%), consanguineous marriage (8%) and previous sibling death (23%) were observed as major clinical predictors/clues for underlying PID. All children received prophylactic antibiotics and/or antifungals in addition to specific therapy for underlying immune deficiency. CONCLUSIONS: The field of PIDs in India remains largely unexplored and we are faced with various challenges in the diagnosis of PIDs due to lack of awareness as well as absence of equipped immunological laboratory support. The authors propose a methodical step-wise laboratory diagnostic approach that can facilitate early diagnosis and timely intervention of these mis/underdiagnosed disorders.