Gut-microbiota modulation: The impact of thegut-microbiotaon osteoarthritis

Osteoarthritis (OA) is one of the most common medical conditions affecting > 300 million people globally which represents the formidable public health challenge. Despite its clinical and financial ramifications, there are currently no approved disease modifying OA drugs available and symptom palliation is the only alternative. Currently, the amount of data on the human intestinal microbiome is growing at a high rate, both in health and in various pathological conditions. With an increase in the amount of the accumulated data, there is an expanded understanding that the microbiome provides compelling evidence of a link between thegut microbiomeand development ofOA. The microbiota management tools of probiotics and/or prebiotics or symbiotic have been developed and indeed, commercialized over the past few decades with the expressed purpose of altering the microbiota within the gastrointestinal tract which could be a potentially novel intervention to tackle or prevent OA. However, the mechanisms how intestinal microbiota affects the OA pathogenesis are still not clear and further research targeting specific gut microbiota or its metabolites is still needed to advance OA treatment strategies from symptomatic management to individualized interventions of OA pathogenesis. This article provides an overview of the various preclinical and clinical studies using probiotics and prebiotics as plausible therapeutic options that can restore the gastrointestinal microbiota and its impact on the OA pathogenesis. May be in the near future the targeted alterations of gut microbiota may pave the way for developing new interventions to prevent and treat OA.

Ropivacaine attenuates endotoxin plus hyperinflation-mediated acute lung injury via inhibition of early-onset Src-dependent signaling

Background

Acute lung injury (ALI) is associated with high mortality due to the lack of effective therapeutic strategies. Mechanical ventilation itself can cause ventilator-induced lung injury. Pulmonary vascular barrier function, regulated in part by Src kinase-dependent phosphorylation of caveolin-1 and intercellular adhesion molecule-1 (ICAM-1), plays a crucial role in the development of protein-/neutrophil-rich pulmonary edema, the hallmark of ALI. Amide-linked local anesthetics, such as ropivacaine, have anti-inflammatory properties in experimental ALI. We hypothesized ropivacaine may attenuate inflammation in a “double-hit” model of ALI triggered by bacterial endotoxin plus hyperinflation via inhibition of Src-dependent signaling.

Methods

C57BL/6 (WT) and ICAM-1^−/− mice were exposed to either nebulized normal saline (NS) or lipopolysaccharide (LPS, 10 mg) for 1 hour. An intravenous bolus of 0.33 mg/kg ropivacaine or vehicle was followed by mechanical ventilation with normal (7 ml/kg, NTV) or high tidal volume (28 ml/kg, HTV) for 2 hours. Measures of ALI (excess lung water (ELW), extravascular plasma equivalents, permeability index, myeloperoxidase activity) were assessed and lungs were homogenized for Western blot analysis of phosphorylated and total Src, ICAM-1 and caveolin-1. Additional experiments evaluated effects of ropivacaine on LPS-induced phosphorylation/expression of Src, ICAM-1 and caveolin-1 in human lung microvascular endothelial cells (HLMVEC).

Results

WT mice treated with LPS alone showed a 49% increase in ELW compared to control animals (p = 0.001), which was attenuated by ropivacaine (p = 0.001). HTV ventilation alone increased measures of ALI even more than LPS, an effect which was not altered by ropivacaine. LPS plus hyperinflation (“double-hit”) increased all ALI parameters (ELW, EVPE, permeability index, MPO activity) by 3–4 fold compared to control, which were again decreased by ropivacaine. Western blot analyses of lung homogenates as well as HLMVEC treated in culture with LPS alone showed a reduction in Src activation/expression, as well as ICAM-1 expression and caveolin-1 phosphorylation. In ICAM-1^−/− mice, neither addition of LPS to HTV ventilation alone nor ropivacaine had an effect on the development of ALI.

Conclusions

Ropivacaine may be a promising therapeutic agent for treating the cause of pulmonary edema by blocking inflammatory Src signaling, ICAM-1 expression, leukocyte infiltration, and vascular hyperpermeability.

Carboxypeptidase M activity is increased in bronchoalveolar lavage in human lung disease

Carboxypeptidase M (CPM) cleaves the C-terminal arginine and lysine of peptides; it is expressed in the lung, especially on the plasma membrane of alveolar type I cells. Here, we report on CPM in human bronchoalveolar lavage (BAL) collected from 69 patients and analyzed for activity, cell number and type, and protein level. Seventy-six percent of CPM activity, measured at pH 7.5 with 5-dimethylamino-naphthalene-1-sulfonyl-alanyl-arginine (Dansyl-Ala-Arg) substrate, was immunoprecipitated with polyclonal antibody to purified human enzyme. In patients without active lung disease, CPM activity in BAL was 7.69 (+/- 2.12) nmol/h/mg protein, but in patients with acute pneumonia, it was 29.25 (+/- 4.06) (p < 0.01). In patients with Pneumocystis carinii pneumonia, CPM activity was elevated to 26.00 (+/- 4.85) (p < 0.01) and in patients with lung cancer, to 30.95 (+/- 4.12) (p < 0.01). The activity was not associated with the cellular elements of BAL. The highest specific activity was in the large aggregate fraction of surfactant, which also contained the highest concentration of phosphorus. Transmission electron microscopy of this fraction revealed the presence of typical lamellar bodies and tubular myelin structures. The high CPM activity may stem from its induction and release in acute lung disease. In addition, CPM may be a marker of infection with certain pathogens and an indicator of type I cell injury in parenchymal lung diseases.