Regulation of antigen-specific versus by-stander IgE production after antigen sensitization

IgE is critical in the pathogenesis of allergic disorders. In this report, we investigated the differential regulation of antigen-specific and by-stander IgE. Ovalbumin (OVA) immunization did not increase IgE producing cells in the spleen, but significantly enhanced the intracellular IgE content of all IgE+ cells. In contrast, OVA induced a significant increase of IgE+ cells in the draining lymph nodes (LN). Furthermore, OVA-specific IgE was detected only in the ex vivo cultures of the draining LN but not the spleen cells, while total IgE was increased in both cultures. These results indicated that antigen-specific IgE was mainly produced in the draining LN, while the spleen was a major source for by-stander IgE. Anti-IL-4, but not anti-IL-13, antibody blocked the expansion of IgE producing cells in the draining LN as well as systemic OVA-specific and total IgE levels, indicating IL-4 was important in both antigen-specific IgE generation and total IgE upregulation.     

TIRC7 deficiency causes in vitro and in vivo augmentation of T and B cell activation and cytokine response

The membrane protein T cell immune response cDNA 7 (TIRC7) was recently identified and was shown to play an important role in T cell activation. To characterize the function of TIRC7 in more detail, we generated TIRC7-deficient mice by gene targeting. We observed disturbed T and B cell function both in vitro and in vivo in TIRC7(-/-) mice. Histologically, primary and secondary lymphoid organs showed a mixture of hypo-, hyper-, and dysplastic changes of multiple lymphohemopoietic compartments. T cells from TIRC7(-/-) mice exhibited significantly increased proliferation and expression of IL-2, IFN-gamma, and IL-4 in response to different stimuli. Resting T cells from TIRC7(-/-) mice exhibited decreased CD62L, but increased CD11a and CD44 expression, suggesting an in vivo expansion of memory/effector T cells. Remarkably, activated T cells from TIRC7(-/-) mice expressed lower levels of CTLA-4 in comparison with wild-type cells. B cells from TIRC7-deficient mice exhibited significantly higher in vitro proliferation following stimulation with anti-CD40 Ab or LPS plus IL-4. B cell hyperreactivity was reflected in vivo by elevated serum levels of various Ig classes and higher CD86 expression on B cells. Furthermore, TIRC7 deficiency resulted in an augmented delayed-type hypersensitivity response that was also reflected in increased mononuclear infiltration in the skin obtained from TIRC7-deficient mice food pads. In summary, the data strongly support an important role for TIRC7 in regulating both T and B cell responses.     

Secondary heterologous dengue infection risk: Disequilibrium between immune regulation and inflammation?

Increased serum levels of cytokines released by cells of the immune response have been detected in patients suffering from dengue disease. Likewise, secondary infections by a different dengue virus serotype result in a highest risk of development of the severe dengue disease. Both findings suggest that the memory immune response is one of the key players in the pathogenesis of this disease. Here we take advantage of the particular Cuban epidemiological situation in dengue to analyze a broad spectrum of cell-mediated immune response mediators at mRNA and protein level. Evidences for a regulatory immune pattern in homologous (TGF-β, IL-10) vs. pro-inflammatory pattern (IFN-γ, TNF-α) in heterologous dengue virus re-challenge were found, suggesting a possible association with the higher incidence of severe dengue cases in the latter case.     

Minimizing Nitrate Reduction during Kjeldahl Digestion of Plant Tissue Extracts and Stem Exudates : APPLICATION TO N STUDIES

From 10 to 60% of the nitrate present in plant tissue extracts and stem exudates of corn (Zea mays L.) was found to be reduced during Kjeldahl digestion, even in the absence of added reducing agents. This reduction is of particular concern in [¹⁵N]nitrate assimilation studies, because it results in an overestimate of nitrate reduction. To overcome this problem, a method was developed for removing nitrate prior to Kjeldahl digestion, thereby preventing nitrate reduction. The procedure utilizes hydrogen peroxide for partial oxidation of organic matter in order to minimize the nitration of organic compounds. The free nitrates are then volatilized as nitric acid from concentrated sulfuric acid at 95°C. When the proposed method was used as a pretreatment to Kjeldahl digestion, less than 0.5% of the applied nitrate was recovered in the reduced nitrogen fraction of plant tissue extracts and stem exudates.     

Inflammatory phase of bone healing initiates the regenerative healing cascade

Bone healing commences with an inflammatory reaction which initiates the regenerative healing process leading in the end to reconstitution of bone. An unbalanced immune reaction during this early bone healing phase is hypothesized to disturb the healing cascade in a way that delays bone healing and jeopardizes the successful healing outcome. The immune cell composition and expression pattern of angiogenic factors were investigated in a sheep bone osteotomy model and compared to a mechanically-induced impaired/delayed bone healing group. In the impaired/delayed healing group, significantly higher T cell percentages were present in the bone hematoma and the bone marrow adjacent to the osteotomy gap when compared to the normal healing group. This was mirrored in the higher cytotoxic T cell percentage detected under delayed bone healing conditions indicating longer pro-inflammatory processes. The highly activated periosteum adjourning the osteotomy gap showed lower expression of hematopoietic stem cell markers and angiogenic factors such as heme oxygenase and vascular endothelial growth factor. This indicates a deferred revascularization of the injured area due to ongoing pro-inflammatory processes in the delayed healing group. Results from this study suggest that there are unfavorable immune cells and factors participating in the initial healing phase. In conclusion, identifying beneficial aspects may lead to promising therapeutical approaches that might benefit further by eliminating the unfavorable factors.     

Organelle positioning in muscles requires cooperation between two KASH proteins and microtubules

Striated muscle fibers are characterized by their tightly organized cytoplasm. Here, we show that the Drosophila melanogaster KASH proteins Klarsicht (Klar) and MSP-300 cooperate in promoting even myonuclear spacing by mediating a tight link between a newly discovered MSP-300 nuclear ring and a polarized network of astral microtubules (aMTs). In either klar or msp-300(ΔKASH), or in klar and msp-300 double heterozygous mutants, the MSP-300 nuclear ring and the aMTs retracted from the nuclear envelope, abrogating this even nuclear spacing. Anchoring of the myonuclei to the core acto-myosin fibrillar compartment was mediated exclusively by MSP-300. This protein was also essential for promoting even distribution of the mitochondria and ER within the muscle fiber. Larval locomotion is impaired in both msp-300 and klar mutants, and the klar mutants were rescued by muscle-specific expression of Klar. Thus, our results describe a novel mechanism of nuclear spacing in striated muscles controlled by the cooperative activity of MSP-300, Klar, and astral MTs, and demonstrate its physiological significance.     

Systems analysis of primary Sjögren's syndrome pathogenesis in salivary glands identifies shared pathways in human and a mouse model

Bone tissue has an exceptional quality to regenerate to native tissue in response to injury. However, the fracture repair process requires mechanical stability or a viable biological microenvironment or both to ensure successful healing to native tissue. An improved understanding of the molecular and cellular events that occur during bone repair and remodeling has led to the development of biologic agents that can augment the biological microenvironment and enhance bone repair. Orthobiologics, including stem cells, osteoinductive growth factors, osteoconductive matrices, and anabolic agents, are available clinically for accelerating fracture repair and treatment of compromised bone repair situations like delayed unions and nonunions. Preclinical and clinical studies using biologic agents like recombinant bone morphogenetic proteins have demonstrated an efficacy similar or better than that of autologous bone graft in acute fracture healing. A lack of standardized outcome measures for comparison of biologic agents in clinical fracture repair trials, frequent off-label use, and a limited understanding of the biological activity of these agents at the bone repair site have limited their efficacy in clinical applications.