Hidden consequences: Uncovering belimumab's role in the development of Pneumocystis jirovecii pneumonia in a lupus patient.

INTRODUCTION: Pneumocystis jirovecii is an opportunistic fungal organism that can cause fatal pneumonia in immunocompromised individuals. It is a disease associated with CD4+ T cell depletion or high-dose steroids. However, there is increasing evidence that B cell dysfunction may also play a role in this illness. CASE REPORT: A 33-year-old female with SLE, who was maintained on belimumab and low-dose prednisone (2.5 mg daily), presented with progressive cough and shortness of breath. She had been on monthly belimumab and prednisone 2.5 mg daily for 19 months, and her CD4 count was >200/uL, but her CD19+ B cell was <1% due to the belimumab. She developed a persistent cough and progressive dyspnea that did not respond to empiric antibiotic therapy for pneumonia. She went to the hospital for acute worsening of her dyspnea and cough. An extensive workup was performed, including a VATS procedure and surgical biopsy, which gave a definitive diagnosis of PJP. The patient was treated and discharged on trimethoprim-sulfamethoxazole. She made a complete recovery. DISCUSSION: Our report demonstrates the first confirmed case of pneumocystis jirovecii pneumonia in a patient with B cell depletion due to chronic maintenance therapy with belimumab. Our patient's diagnosis of PJP was unexpected, given her normal CD4+ count and the use of such a low dose of prednisone. We attribute her susceptibility to PJP infection to her profound B cell depletion in response to her belimumab therapy, supporting previous research indicating the importance of CD4+ T cells and B cells in the protective immune response against PJP. This case may help shape future clinical guidelines concerning PJP prophylaxis, particularly in SLE patients with deficient B lymphocytic activity and B cell depletion.

Evaluation of Mitoquinone for Protecting Against Amikacin-Induced Ototoxicity in Guinea Pigs.

HYPOTHESIS: Mitoquinone (MitoQ) attenuates amikacin ototoxicity in guinea pigs. BACKGROUND: MitoQ, a mitochondria-targeted derivative of the antioxidant ubiquinone, has improved bioavailability and demonstrated safety in humans. Thus, MitoQ is a promising therapeutic approach for protecting against amikacin-induced ototoxicity. METHODS: Both oral and subcutaneous administrations of MitoQ were tested. Amikacin-treated guinea pigs (n = 12-18 per group) received water alone (control) or MitoQ 30 mg/l-supplemented drinking water; or injected subcutaneously with 3 to 5 mg/kg MitoQ or saline (control). Auditory brainstem responses and distortion product otoacoustic emissions were measured before MitoQ or control solution administration and after amikacin injections. Cochlear hair cell damage was assessed using scanning electron microscopy and Western blotting. RESULTS: With oral administration, animals that received 30 mg/l MitoQ had better hearing than controls at only 24 kHz at 3-week (p = 0.017) and 6-week (p = 0.027) post-amikacin. With subcutaneous administration, MitoQ-injected guinea pigs had better hearing than controls at only 24 kHz, 2-week post-amikacin (p = 0.013). Distortion product otoacoustic emission (DPOAE) amplitudes were decreased after amikacin injections, but were not different between treatments (p > 0.05). Electron microscopy showed minor difference in outer hair cell loss between treatments. Western blotting demonstrated limited attenuation of oxidative stress in the cochlea of MitoQ-supplemented guinea pigs. CONCLUSIONS: Oral or subcutaneous MitoQ provided limited protection against amikacin-induced hearing loss and cochlear damage in guinea pigs. Other strategies for attenuating aminoglycoside-induced ototoxicity should be explored.

Ciprofloxacin Decreases Collagen in Mouse Tympanic Membrane Fibroblasts.

OBJECTIVES: To determine how collagen production by tympanic membrane fibroblasts is affected by ciprofloxacin at levels found in eardrops. STUDY DESIGN: Prospective, controlled, and blinded cell culture study. SETTING: Academic tertiary medical center. SUBJECTS: Cell culture of mouse fibroblasts. METHODS: A primary fibroblast culture was established from mouse tympanic membranes. Fibroblasts were cultured until they were 75% confluent, then treated with dilute hydrochloric acid (control) or ciprofloxacin (0.01% or 0.3%) for 24 or 72 hours for Western blotting and for 24 or 48 hours for cytotoxicity assay. Cells were observed with phase-contrast microscope. Western blotting was performed for collagen type 1 α1 (collagen 1A1) and α-tubulin. RESULTS: Fibroblasts treated with 0.01% and 0.3% ciprofloxacin for 24 hours had lower levels of collagen 1A1 (P = .0005 and P < .0001, respectively) and α-tubulin (both P < .0001) than control fibroblasts. Collagen 1A1 and α-tubulin levels were lower in fibroblasts treated with 0.3% than with 0.01% ciprofloxacin (P = .02 and P = .014). After 72 hours, 0.3% ciprofloxacin completely eliminated collagen 1A1 and α-tubulin (P < .001). Cells treated with 0.01% ciprofloxacin for 72 hours also had lower collagen 1A1 (P < .0001) and α-tubulin (P = .005) as compared with the control. Seventy-two-hour incubation in 0.01% or 0.3% ciprofloxacin resulted in lower levels of collagen 1A1 (P = .009 and P < .0001, respectively) and α-tubulin (P = .007 and P < .0001, respectively) than 24-hour incubation. Cytotoxicity assay and phase-contrast microscopy mirrored these findings. CONCLUSIONS: Treatment of tympanic membrane fibroblasts with 0.3% ciprofloxacin, as found in eardrops, reduces fibroblast viability and collagen and α-tubulin protein levels. These findings could explain tympanic membrane healing problems associated with quinolone eardrops.

Assessment of mitochondrial membrane potential in HEI-OC1 and LLC-PK1 cells treated with gentamicin and mitoquinone.

OBJECTIVE: To determine the effects of concurrent treatment with gentamicin and the mitochondria-targeted antioxidant mitoquinone (MitoQ; which may prevent gentamicin ototoxicity) on change in the mitochondrial membrane potential (Δψ(m)), a precursor of apoptosis. STUDY DESIGN: Prospective and controlled. SETTING: Academic research laboratory. SUBJECTS AND METHODS: LLC-PK1 (Lilly Laboratories Culture-Pig Kidney Type 1) and HEI-OC1 (House Ear Institute Organ of Corti 1) cells-renal and auditory cell lines, respectively-were used in this study. Δψ(m) was assessed by flow cytometry through the MitoProbe JC-1 Kit for Flow Cytometry in untreated LLC-PK1 and HEI-OC1 cells and cells exposed to low- (100µM) or high- (2000µM) dose gentamicin for 24 hours, with and without 0.5µM each of MitoQ or idebenone (IDB; an untargeted ubiquinone). RESULTS: Δψ(m) was not different in untreated LLC-PK1 cells and cells coincubated with low-dose gentamicin and MitoQ or IDB (P > .05). In HEI-OC1 cells, coincubation with low-dose gentamicin and MitoQ decreased Δψ(m) (P = .002). Coincubation of LLC-PK1 cells with high-dose gentamicin and DMSO, MitoQ, or IDB depolarized Δψ(m) (P < .0001), with MitoQ depolarizing the Δψ(m) to a greater extent than that of IDB (P = .03). In contrast, HEI-OC1 cells demonstrated a hyperpolarized Δψ(m) when coincubated with high-dose gentamicin and DMSO, MitoQ, or IDB (P < .001). CONCLUSION: The combination of gentamicin and MitoQ holds the potential to disrupt Δψ(m). This suggests a heightened need to monitor for toxicity in patients receiving both agents.

Rheos: an implantable carotid sinus stimulation device for the nonpharmacologic treatment of resistant hypertension.

Hypertension is a highly prevalent disorder in the United States. Of particular concern is resistant hypertension, which by definition is hypertension that cannot be adequately treated by conventional 3-drug regimens. The Rheos Baroreflex Hypertension Therapy System is a new implantable device that can treat patients with hypertension resistant to multidrug therapy, by activating the carotid baroreflex through electrical stimulation of the carotid sinus wall. Recent studies in both normotensive and hypertensive canine models have demonstrated sustained and clinically relevant reductions in arterial pressure and sympathetic activity with prolonged baroreflex activation. Clinical trials designed to evaluate the efficacy and safety of this therapy in patients with treatment resistant hypertension, are now ongoing in both Europe and the United States.

The "push-to-low" approach for optimization of high-density perfusion cultures of animal cells.

High product titer is considered a strategic advantage of fed-batch over perfusion cultivation mode. The titer difference has been experimentally demonstrated and reported in the literature. However, the related theoretical aspects and strategies for optimization of perfusion processes with respect to their fed-batch counterparts have not been thoroughly explored. The present paper introduces a unified framework for comparison of fed-batch and perfusion cultures, and proposes directions for improvement of the latter. The comparison is based on the concept of "equivalent specific perfusion rate", a variable that conveniently bridges various cultivation modes. The analysis shows that development of economically competitive perfusion processes for production of stable proteins depends on our ability to dramatically reduce the dilution rate while keeping high cell density, i.e., operating at low specific perfusion rates. Under these conditions, titer increases significantly, approaching the range of fed-batch titers. However, as dilution rate is decreased, a limit is reached below which performance declines due to poor growth and viability, specific productivity, or product instability. To overcome these limitations, a strategy referred to as "push-to-low" optimization has been developed. This approach involves an iterative stepwise decrease of the specific perfusion rate, and is most suitable for production of stable proteins where increased residence time does not compromise apparent specific productivity or product quality. The push-to-low approach was successfully applied to the production of monoclonal antibody against tumor necrosis factor (TNF). The experimental results followed closely the theoretical prediction, providing a multifold increase in titer. Despite the medium improvement, reduction of the specific growth rate along with increased apoptosis was observed at low specific perfusion rates. This phenomenon could not be explained with limitation or inhibition by the known nutrients and metabolites. Even further improvement would be possible if the cause of apoptosis were understood. In general, a strategic target in the optimization of perfusion processes should be the decrease of the cell-specific perfusion rate to below 0.05 nL/cell/day, resulting in high, batch-like titers. The potential for high titer, combined with high volumetric productivity, stable performance over many months, and superior product/harvest quality, make perfusion processes an attractive alternative to fed-batch production, even in the case of stable proteins.