Pulmonary Mycobacterium abscessus Infection with Reactive AA Amyloidosis: A Case Report and Brief Review of the Literature

Inflammatory brachial artery aneurysm with amyloidosis due to nontuberculous mycobacterial infection: a case report

The patient was a 72-year-old man with a history of kidney transplantation and long-term administration of methylprednisolone and immunosuppressants who underwent resection and reconstruction of a brachial artery aneurysm. A pathological examination confirmed mycobacteria, indicating an inflammatory aneurysm with amyloid kappa light chain deposition caused by intracellular nontuberculous mycobacterium. To our knowledge, this is the first demonstration of an inflammatory brachial artery aneurysm with amyloidosis caused by nontuberculous mycobacterial infection. When a nontuberculous mycobacterial infection is diagnosed, it is important to take into account the potential development of aneurysms at locations outside of the lungs.

Systemic Amyloid A Amyloidosis Secondary to Xanthogranulomatous Pyelonephritis

The combination of systemic amyloid A (AA) amyloidosis and xanthogranulomatous pyelonephritis (XGP) resulting from a chronic urinary tract infection is extremely rare. We herein report a case of systemic AA amyloidosis secondary to XGP for which clinical remission developed after nephrectomy. To our knowledge, this is the first case report describing the clinical improvement of systemic AA amyloidosis secondary to XGP after nephrectomy in Japan. Clinicians should be aware of this uncommon combination and search for amyloid depositions in cases of XGP.

Mechanical Forces between Mycobacterial Antigen 85 Complex and Fibronectin

Adhesion to extracellular matrix proteins is an important first step in host invasion, employed by many bacterial pathogens. In mycobacteria, the secreted Ag85 complex proteins, involved in the synthesis of the cell envelope, are known to bind to fibronectin (Fn) through molecular forces that are currently unknown. In this study, single-molecule force spectroscopy is used to study the strength, kinetics and thermodynamics of the Ag85-Fn interaction, focusing on the multidrug-resistant Mycobacterium abscessus species. Single Ag85 proteins bind Fn with a strength of ~75 pN under moderate tensile loading, which compares well with the forces reported for other Fn-binding proteins. The binding specificity is demonstrated by using free Ag85 and Fn peptides with active binding sequences. The Ag85-Fn rupture force increases with mechanical stress (i.e., loading rate) according to the Friddle–Noy–de Yoreo theory. From this model, we extract thermodynamic parameters that are in good agreement with previous affinity determinations by surface plasmon resonance. Strong bonds (up to ~500 pN) are observed under high tensile loading, which may favor strong mycobacterial attachment in the lung where cells are exposed to high shear stress or during hematogenous spread which leads to a disseminated infection. Our results provide new insight into the pleiotropic functions of an important mycobacterial virulence factor that acts as a stress-sensitive adhesin.