Molecular basis of rifampicin-induced inhibition of anti-CD95-induced apoptosis of peripheral blood T lymphocytes: the role of CD95 ligand and FLIPs

The effect of systemic rifampicin treatment on inferior alveolar nerve regeneration in rats following crush injury

Axonal regeneration of the inferior alveolar nerve (IAN) is a therapeutic target for functional recovery after peripheral nerve injury. Rifampicin exerts anti-apoptotic, anti-inflammatory, and anti-oxidant effects on nerve tissues that may enhance functional recovery after peripheral nerve injury. The aim of the present study was to evaluate the therapeutic effects of systemic rifampicin following IAN crush injury. Following the nerve crush injuries of the IAN, 24 Sprague-Dawley rats were randomly divided into three groups to receive daily intraperitoneal injections of either vehicle, 5 mg kg^-1 rifampicin, or 20 mg kg^-1 rifampicin. Twenty-four days after induction of nerve injuries, Fluorogold (FG) was injected over the mental foramen for the evaluation of neuronal survival. At the end of the four-week period, histologic and histomorphometric examination of IAN samples were performed and FG positive cells were counted in the trigeminal ganglion sections. FG positive cells were significantly more frequent in the 20 and 5 mg kg^-1 rifampicin groups than in the vehicle-treated group. Electron microscopic analyses revealed that the percentage of axons with optimum g-ratio was significantly lower in the vehicle group than in both treatment groups. In conclusion, systemic rifampicin treatment can enhance peripheral nerve regeneration.

Long-term clinical safety of clindamycin and rifampicin combination for the treatment of hidradenitis suppurativa. A Critically Appraised Topic

CLINICAL QUESTION/SCENARIO

Can therapy with clindamycin and rifampicin be safely continued long term beyond the recommended 10-week course?

BACKGROUND

Clindamycin and rifampicin are used in combination to treat hidradenitis suppurativa (HS). There is no data on the efficacy and safety of clindamycin/rifampicin combination therapy for HS beyond 10 weeks.

METHODS

We identified the following major concerns that still lack a proper evidenced-based analysis: for rifampicin, drug-induced liver injury, interstitial nephritis, drug interaction and hepatic p450 3A4 enzyme induction; for clindamycin, the concern was community-acquired Clostridium difficile infection (CA-CDI); and experience with long-term treatment. Data sources were used as appropriate to answer the question. Systematic searches were used to assess the risk of CA-CDI and experience with long-term treatment with clindamycin.

RESULTS/IDENTIFIED EVIDENCE

The risk for rifampicin-induced liver injury is highest in the first 6 weeks of treatment, whereas interstitial nephritis is primarily observed during intermittent treatment. Enzyme induction due to rifampicin is usually complete after about 2 weeks of treatment and reduces clindamycin blood levels by about 90%. Three meta-analyses identified antibiotic use as a risk factor for CA-CDI. Two of them assigned the highest risk to clindamycin. None of them stratified by length of treatment. There is extensive experience with rifampicin, primarily for the treatment of tuberculosis. Long-term experience with clindamycin is limited.

DISCUSSION AND RECOMMENDATION FOR CLINICAL CARE

The analysed risks associated with a combination of clindamycin and rifampicin for hidradenitis suppurative cluster within the first 10 weeks. Treatment can be continued beyond 10 weeks, if clinically necessary.

Development of a stretch-induced neurotrauma model for medium-throughput screening in vitro: identification of rifampicin as a neuroprotectant

BACKGROUND AND PURPOSE

We hypothesized that an in vitro, stretch-based model of neural injury may be useful to identify compounds that decrease the cellular damage in neurotrauma.

EXPERIMENTAL APPROACH

We screened three neural cell lines (B35, RN33B and SH-SY5Y) subjected to two differentiation methods and selected all-trans-retinoic acid-differentiated B35 rat neuroblastoma cells subjected to rapid stretch injury, coupled with a subthreshold concentration of H₂ O₂ , for the screen. The model induced marked alterations in gene expression and proteomic signature of the cells and culminated in delayed cell death (LDH release) and mitochondrial dysfunction [reduced 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) conversion]. Follow-up studies utilized human stem cell-derived neurons subjected to rapid stretch injury.

KEY RESULTS

From screening of a composite library of 3500 drugs, five drugs (when applied in a post-treatment regimen relative to stretch injury) improved both LDH and MTT responses. The effects of rifampicin were investigated in further detail. Rifampicin reduced cell necrosis and apoptosis and improved cellular bioenergetics. In a second model (stretch injury in human stem cell-derived neurons), rifampicin pretreatment attenuated LDH release, protected against the loss of neurite length and maintained neuron-specific class III β-tubulin immunoreactivity.

CONCLUSIONS AND IMPLICATIONS

We conclude that the current model is suitable for medium-throughput screening to identify compounds with neuroprotective potential. Rifampicin, when applied either in pre- or post-treatment, improves the viability of neurons subjected to stretch injury and protects against neurite loss. Rifampicin may be a candidate for repurposing for the therapy of traumatic brain injury.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

RIFAMPICIN: an antibiotic with brain protective function

Besides its well known antibiotic activity rifampicin exerts multiple brain protective functions in acute cerebral ischemia and chronic neurodegeneration. The present mini-review gives an update of the unique activity of rifampicin in different diseases including Parkinson's disease, meningitis, stroke, Alzheimer's disease and optic nerve injury.

Effects of intraocular rifampicin on retinal ganglion cell structure: a stereological and histopathological study

AIM

To determine the histopathological changes of rifampicin applied intravitreally on retinal ganglion cells by means of stereological and histopathological methods.

METHODS

For this study twenty-four New Zealand adult rabbits were divided into four groups (n=6 for each group). 50µg/0.1mL (group 1), 100µg/0.1mL (group 2), 150µg/0.1mL (group 3) and 200µg/0.1mL (group 4), rifampicin were injected into the vitreous of the right eyes of animals, their left eyes were used as control (group 5). After the 28(th) day of application, animals were anesthetised with xylazine (8mg/kg, IM) and then their eyes were enucleated immediately. Patterns were taken away and eyes were prepared for both stereological and electromicroscopic observation.

RESULTS

Depending on the high dose of rifampicin, some histopathological changes such as cytoplasmic dilatation and damaged membrane were observed on the electromicroscopic level. Using quantitative examination, which was done at the light microscopic level, it was shown that the number of neurons decreased linearly as rifampicin dose increased when compared with the control group.

CONCLUSION

Based on these findings, low-dose rifampicin (50µg/0.1mL) may be useful for treatment of the ocular diseases.

Immunomodulating Activity of Rifampicin

It has been shown that some antibiotics can modify cytokine production. We have examined the effect of rifampicin on secretion of interleukin-1beta (IL-1beta), IL-6, IL-10, and tumor necrosis factor alpha (TNF-alpha) by lipopolysaccharide (LPS)-stimulated or heat killed staphylococci (Pansorbin) stimulated monocytes. Secretion of IL-1beta and TNF-a were significantly inhibited (P<0.002) whereas secretion of IL-6 and IL-10 were significantly increased (P<0.003) by rifampicin treated mononuclear cells. Rifampicin had immunomodulatory effects through its capacity to alter the secretion of tested cytokines by human monocytes.

Rifampicin attenuates the MPTP-induced neurotoxicity in mouse brain

Rifampicin, an antibacterial drug, is highly effective in the treatment of tuberculosis and leprosy. Recently, it has been reported to have neuroprotective effects in in vitro and in vivo models. This study was designed to elucidate its neuroprotective effects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity (known as an in vivo mouse model of Parkinson's disease). Mice were injected intraperitoneally (i.p.) with MPTP (10 mg/kg) four times at 1-h intervals, and brains were analyzed 3 or 7 days later. Rifampicin at 20 mg/kg (i.p., twice) had protective effects against MPTP-induced neuronal damage (immunohistochemical changes in tyrosine hydroxylase) in both the substantia nigra and striatum. Rifampicin also protected against the MPTP-induced depletions of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) in the striatum. The maximal concentrations of rifampicin between 30 and 240 min after a single rifampicin injection (20 mg/kg, i.p.) were 2.6 microM (at 30 min) in plasma and 0.77 microM (at 60 min) in striatum. Next, the effects of rifampicin on oxidative stress [lipid peroxidation in mouse brain homogenates and free radical-scavenging activity against diphenyl-p-picrylhydrazyl (DPPH)] were evaluated to clarify the underlying mechanism. At 1 microM or more, rifampicin significantly inhibited both lipid peroxidation in the striatum and free radical production. These findings suggest that in mice, rifampicin can reach brain tissues at concentrations sufficient to attenuate MPTP-induced neurodegeneration in the nigrostriatal dopaminergic neuronal pathway, and that an inhibitory effect against oxidative stress may be partly responsible for its observed neuroprotective effects.

Anti-inflammatory activity of ansamycins

Inflammation represents a complex biologic and biochemical process involving cells of the immune system and a plethora of biologic mediators in response to mechanical, chemical or infectious injuries. When mobilization of effector cells and molecules becomes excessive, the beneficial aspect of this response--to limit damage and promote healing, can be overriden, resulting in host-cell and tissue dysfunction. Based on the hypothesis that chronic infections underly some inflammatory diseases, antibacterial therapy has long been assessed in various inflammatory settings. Recently, the anti-inflammatory activity of some antibacterial agents has also been suspected. Of these duel-action drugs, ansamycins represent an interesting family. Although their therapeutic use is restricted to potentially infectious inflammatory diseases, many experimental data suggest that these drugs also possess direct inhibitory activity on some crucial proinflammatory effectors. To date, the potent antimycobacterial activity of the therapeutically useful ansamycins precludes their widespread use in inflammatory diseases. However, biosynthetic manipulation remains an attractive route for the generation of pharmacologically useful analogs.

Rifampicin attenuates brain damage in focal ischemia

Rifampicin is an antibacterial agent that is widely used in tuberculosis and leprosy therapy. Interestingly, some experimental studies indicate that rifampicin acts as a hydroxyl radical scavenger and a glucocorticoid receptor activator. In this study, the neuroprotective effect of rifampicin was evaluated after transient and permanent focal cerebral ischemia. Anaesthetized male C57BL/6j mice were submitted to permanent or transient thread occlusion of the middle cerebral artery (MCA). Reperfusion in transient ischemia was initiated 30 min later by thread retraction. Rifampicin or vehicle were applied intraperitoneally before permanent or immediately after 30 min of transient ischemia. Later, 24 h after permanent or transient ischemia, animals were re-anesthetized and decapitated. Brain injury was evaluated by triphenyltetrazolium chloride staining (TTC), terminal transferase biotinylated-dUTP nick end labeling (TUNEL) and cresyl violet staining. A 20-mg/kg sample of rifampicin showed a significant neuroprotection after cerebral ischemia. The number of TUNEL-positive cells in the striatum, where disseminated tissue injury was observed, was also reduced by application of rifampicin as compared with vehicle-treated animals. The present report shows that administration of rifampicin efficiently reduces brain injury after permanent and transient focal cerebral ischemia in mice.