Septic polyarthritis with Mycoplasma salivarium in a patient with common variable immunodeficiency: case report and review of the literature.

Mycoplasma salivarium is a common mycoplasma usually isolated from human oropharynx, particularly from individuals with periodontal disease. It is also among the more common mycoplasmal contaminants of eukaryotic cell cultures. Although M. salivarium has been isolated occasionally from abscesses and other sterile sites, to our knowledge, only three cases of septic arthritis have been documented in the past due to this organism, all in patients with humoral immunodeficiency. We now report a fourth case of septic polyarthritis in a patient with profound hypoimmunoglobulinemia who had experienced dental abscesses within the preceding 2 years. Our case highlights the importance of considering invasive mycoplasmal infection in hypogammaglobulinemic patients. It is likely of significance that the patient had suffered recurrent dental abscesses as a source of infection with M. salivarium .

Use of FEF25-75% to Guide IgG Dosing to Protect Pulmonary Function in CVID.

Immunoglobulin replacement therapy (IGRT) can protect against lung function decline in CVID. We tested whether increasing IgG dosage was beneficial in patients who exhibited a decline in forced expiratory flow at 25-75% (FEF25-75%) even though they were receiving IgG doses within the therapeutic range. Of 189 CVID patients seen over 12 years, 38 patients met inclusion criteria, were seen on ≥ 3 visits, and demonstrated a ≥ 10% decrease in FEF25-75% from visits 1 to 2. FEF25-75%, forced expiratory flow at 1 s (FEV1), and FEV1/FVC at visit 3 were compared among those with non-dose adjustment (non-DA) versus additional IgG dose adjustment (DA). Three FEF25-75% tiers were identified: top (> 80% predicted), middle (50-80%), and bottom (< 50%). DA and non-DA groups did not differ in clinical infections or bronchodilator use, although the non-DA group tended to use more antibiotics. In the top, normal tier, FEF25-75% increased in DA, but the change did not achieve statistical significance. In the middle moderate obstruction tier, visit 3 FEF25-75% increased among DA but not non-DA sets (11.8 ± 12.4%, p = 0.003 vs. 0.3 ± 9.9%, p = 0.94). Improvement in FEV1/FVC at visit 3 was also significant among DA vs. non-DA (7.2 ± 12.4%, p = 0.04 vs. - 0.2 ± 2.7%, p = 0.85). In the bottom, severe tier, FEF25-75% was unchanged in DA (- 0.5 ± 5.2%, p = 0.79), but increased in non-DA (5.1 ± 5.2%, p = 0.02). Among IGRT CVID patients with moderate but not severe obstruction as assessed by spirometry, increasing IgG dosage led to an increase in FEF25-75% and FEV1/FVC.

Differences in the composition of the human antibody repertoire by B cell subsets in the blood.

The vast initial diversity of the antibody repertoire is generated centrally by means of a complex series of V(D)J gene rearrangement events, variation in the site of gene segment joining, and TdT catalyzed N-region addition. Although the diversity is great, close inspection has revealed distinct and unique characteristics in the antibody repertoires expressed by different B cell developmental subsets. In order to illustrate our approach to repertoire analysis, we present an in-depth comparison of V(D)J gene usage, hydrophobicity, length, DH reading frame, and amino acid usage between heavy chain repertoires expressed by immature, transitional, mature, memory IgD(+), memory IgD(-), and plasmacytes isolated from the blood of a single individual. Our results support the view that in both human and mouse, the H chain repertoires expressed by individual, developmental B cell subsets appear to differ in sequence content. Sequencing of unsorted B cells from the blood is thus likely to yield an incomplete or compressed view of what is actually happening in the immune response of the individual. Our findings support the view that studies designed to correlate repertoire expression with diseases of immune function will likely require deep sequencing of B cells sorted by subset.

G Protein-regulated inducer of neurite outgrowth (GRIN) modulates Sprouty protein repression of mitogen-activated protein kinase (MAPK) activation by growth factor stimulation.

Gα(o/i) interacts directly with GRIN (G protein-regulated inducer of neurite outgrowth). Using the yeast two-hybrid system, we identified Sprouty2 as an interacting partner of GRIN. Gα(o) and Sprouty2 bind to overlapping regions of GRIN, thus competing for GRIN binding. Imaging experiments demonstrated that Gα(o) expression promoted GRIN translocation to the plasma membrane, whereas Sprouty2 expression failed to do so. Given the role of Sprouty2 in the regulation of growth factor-mediated MAPK activation, we examined the contribution of the GRIN-Sprouty2 interaction to CB1 cannabinoid receptor regulation of FGF receptor signaling. In Neuro-2A cells, a system that expresses all of the components endogenously, modulation of GRIN levels led to regulation of MAPK activation. Overexpression of GRIN potentiated FGF activation of MAPK and decreased tyrosine phosphorylation of Sprouty2. Pretreatment with G(o/i)-coupled CB1 receptor agonist attenuated subsequent FGF activation of MAPK. Decreased expression of GRIN both diminished FGF activation of MAPK and blocked CB1R attenuation of MAPK activation. These observations indicate that Gα(o) interacts with GRIN and outcompetes GRIN from bound Sprouty. Free Sprouty then in turn inhibits growth factor signaling. Thus, here we present a novel mechanism of how G(o/i)-coupled receptors can inhibit growth factor signaling to MAPK.