Physiological Role of Alveolar Macrophage in Acute Lower Respiratory Tract Infection: Phagocytosis and Aging

Acute lower respiratory tract infections (LRTIs) are the deadliest communicable diseases. Inhaled pathogens that reach the alveoli are eliminated by lung-resident alveolar macrophages. Bacteria and fungi are detected and phagocytosed by specific pattern recognition receptors (PRRs) that are highly expressed in alveolar macrophages. In addition, early pro-inflammatory responses assist alveolar macrophages in the efficient phagocytosis of these pathogens. Viruses are also directly or indirectly endocytosed by pinocytosis or opsonization, respectively, whereas alveolar macrophages contribute to the prevention of pneumonia by removing endogenous dead cells through an alternate type of phagocytosis, efferocytosis. Macrophage phagocytosis and efferocytosis require not only sufficient expression of the relevant PRRs but also the coordinated interplay of intracellular factors that regulate engulfment. Given the current situation in which emerging infectious diseases spread worldwide, this chapter summarizes the physiological roles of alveolar macrophages in acute LRTIs, focusing on phagocytosis, pro-inflammatory responses, efferocytosis, and their regulatory machinery. This chapter also reviews recent insights into age-associated dysfunction of alveolar macrophages and discusses their relevance to vulnerability to acute LRTIs in the elderly population

The fungal metabolite (+)-terrein abrogates osteoclast differentiation via suppression of the RANKL signaling pathway through NFATc1

Pathophysiological bone resorption is commonly associated with periodontal disease and involves the excessive resorption of bone matrix by activated osteoclasts. Receptor activator of nuclear factor (NF)-κB ligand (RANKL) signaling pathways have been proposed as targets for inhibiting osteoclast differentiation and bone resorption. The fungal secondary metabolite (+)-terrein is a natural compound derived from Aspergillus terreus that has previously shown anti-interleukin-6 properties related to inflammatory bone resorption. However, its effects and molecular mechanism of action on osteoclastogenesis and bone resorption remain unclear. In the present study, we showed that 10 µM synthetic (+)-terrein inhibited RANKL-induced osteoclast formation and bone resorption in a dose-dependent manner and without cytotoxicity. RANKL-induced messenger RNA expression of osteoclast-specific markers including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), the master regulator of osteoclastogenesis, cathepsin K, tartrate-resistant acid phosphatase (Trap) was completely inhibited by synthetic (+)-terrein treatment. Furthermore, synthetic (+)-terrein decreased RANKL-induced NFATc1 protein expression. This study revealed that synthetic (+)-terrein attenuated osteoclast formation and bone resorption by mediating RANKL signaling pathways, especially NFATc1, and indicated the potential effect of (+)-terrein on inflammatory bone resorption including periodontal disease

The Fungal Metabolite (+)-Terrein Abrogates Ovariectomy-Induced Bone Loss and Receptor Activator of Nuclear Factor-kappa B Ligand-Induced Osteoclastogenesis by Suppressing Protein Kinase-C alpha/beta II Phosphorylation

Osteoporosis is a common disease characterized by a systemic impairment of bone mass and microarchitecture that results in fragility fractures. Severe bone loss due to osteoporosis triggers pathological fractures and consequently decreases the daily life activity and quality of life. Therefore, prevention of osteoporosis has become an important issue to be addressed. We have reported that the fungal secondary metabolite (+)-terrein (TER), a natural compound derived from Aspergillus terreus, has shown receptor activator of nuclear factor-kappa B ligand (RANKL)-induced osteoclast differentiation by suppressing nuclear factor of activated T-cell 1 (NFATc1) expression, a master regulator of osteoclastogenesis. TER has been shown to possess extensive biological and pharmacological benefits; however, its effects on bone metabolism remain unclear. In this study, we investigated the effects of TER on the femoral bone metabolism using a mouse-ovariectomized osteoporosis model (OVX mice) and then on RANKL signal transduction using mouse bone marrow macrophages (mBMMs). In vivo administration of TER significantly improved bone density, bone mass, and trabecular number in OVX mice (p < 0.01). In addition, TER suppressed TRAP and cathepsin-K expression in the tissue sections of OVX mice (p < 0.01). In an in vitro study, TER suppressed RANKL-induced phosphorylation of PKC alpha/beta II, which is involved in the expression of NFATc1 (p < 0.05). The PKC inhibitor, GF109203X, also inhibited RANKL-induced osteoclastogenesis in mBMMs as well as TER. In addition, TER suppressed the expression of osteoclastogenesis-related genes, such as Ocstamp, Dcstamp, Calcr, Atp6v0d2, Oscar, and Itgb3 (p < 0.01). These results provide promising evidence for the potential therapeutic application of TER as a novel treatment compound against osteoporosis

Pancreatic Cancer Research beyond DNA Mutations

Pancreatic ductal adenocarcinoma (PDAC) is caused by genetic mutations in four genes: KRAS proto-oncogene and GTPase (KRAS), tumor protein P53 (TP53), cyclin-dependent kinase inhibitor 2A (CDKN2A), and mothers against decapentaplegic homolog 4 (SMAD4), also called the big 4. The changes in tumors are very complex, making their characterization in the early stages challenging. Therefore, the development of innovative therapeutic approaches is desirable. The key to overcoming PDAC is diagnosing it in the early stages. Therefore, recent studies have investigated the multifaced characteristics of PDAC, which includes cancer cell metabolism, mesenchymal cells including cancer-associated fibroblasts and immune cells, and metagenomics, which extend to characterize various biomolecules including RNAs and volatile organic compounds. Various alterations in the KRAS-dependent as well as KRAS-independent pathways are involved in the refractoriness of PDAC. The optimal combination of these new technologies is expected to help treat intractable pancreatic cancer

Clinical Efficacy and Safety of Sitafloxacin 200 mg Once Daily for Refractory Genitourinary Tract Infections

The aim of this ongoing trial is to evaluate the clinical efficacy and safety of sitafloxacin (STFX) 200 mg once daily (QD) for 7 days in patients with refractory genitourinary tract infections, which include recurrent or complicated cystitis, complicated pyelonephritis, bacterial prostatitis, and epididymitis. The primary endpoint is the microbiological efficacy at 5-9 days after the last administration of STFX. Recruitment began in February 2021, and the target total sample size is 92 participants