Klebsiella pneumoniae invasive syndrome with pneumocephalus and extensive cerebral infarction: Case report.

A 54-year-old female with diabetes was admitted with fever and altered consciousness. Laboratory tests revealed venous blood glucose level of 43.79 mmol/L. Computed tomography (CT) scans of the head, chest, and abdomen showed a right-sided pneumothorax, consolidation, and atelectasis in the right lung; a large heterogeneous density lesion with fluid and gas-fluid levels in the liver; and scattered gas shadows in both kidneys, respectively. Blood and puncture fluid cultures indicated infection with Klebsiella pneumoniae. Based on the susceptibility profiles of the isolates, imipenem was administered intravenously to treat the infection. On the third day of hospitalization, the patient's condition worsened, with head CT showing an extensive cerebral infarction and multiple gas accumulations in the right cerebral hemisphere, as well as a large-area cerebral infarction in the left parietal and occipital lobes. Ultimately, the patient died of multiple organ dysfunction on the fourth day after initial presentation. Although the Klebsiella pneumoniae isolates from the patient showed sensitivity to imipenem, this antibiotic shows poor entry into the central nervous system. The death of the patient indicates that the selection of antibiotics that can cross the blood-brain barrier may be crucial in the outcome of this type of case. Therefore, antibiotics that can penetrate the blood-brain barrier should be selected as soon as possible, and empirical treatment must be initiated immediately after clinical suspicion of invasive Klebsiella pneumoniae, even if the diagnosis has not been determined.

A tryptophan metabolite made by a gut microbiome eukaryote induces pro-inflammatory T cells.

The large intestine harbors microorganisms playing unique roles in host physiology. The beneficial or detrimental outcome of host-microbiome coexistence depends largely on the balance between regulators and responder intestinal CD4+ T cells. We found that ulcerative colitis-like changes in the large intestine after infection with the protist Blastocystis ST7 in a mouse model are associated with reduction of anti-inflammatory Treg cells and simultaneous expansion of pro-inflammatory Th17 responders. These alterations in CD4+ T cells depended on the tryptophan metabolite indole-3-acetaldehyde (I3AA) produced by this single-cell eukaryote. I3AA reduced the Treg subset in vivo and iTreg development in vitro by modifying their sensing of TGFß, concomitantly affecting recognition of self-flora antigens by conventional CD4+ T cells. Parasite-derived I3AA also induces over-exuberant TCR signaling, manifested by increased CD69 expression and downregulation of co-inhibitor PD-1. We have thus identified a new mechanism dictating CD4+ fate decisions. The findings thus shine a new light on the ability of the protist microbiome and tryptophan metabolites, derived from them or other sources, to modulate the adaptive immune compartment, particularly in the context of gut inflammatory disorders.

Case report: Trigeminal neuralgia misdiagnosed as glossopharyngeal neuralgia.

Background: Trigeminal neuralgia (TN) and glossopharyngeal neuralgia (GPN) are cranial nerve neuralgias with the same clinical manifestations, pathological features, and trigger factors; their affected sites are adjacent. Performing a magnetic resonance imaging (MRI) examination alone can easily lead to a misdiagnosis. Case presentation: A 72-year-old man had visited another hospital with severe left-sided tongue pain. On MRI, vascular compression of the glossopharyngeal nerve had been visible, with unclear evidence of trigeminal nerve involvement. He had been diagnosed with left-sided GPN and underwent microvascular decompression (MVD) of the left glossopharyngeal nerve. However, no improvement was observed after surgery. During a second surgery at our hospital, MVD of the trigeminal nerve was performed, and the trigeminal nerve was fully explored and separated. The patient's pain resolved after surgery. Ultimately, the patient was definitively diagnosed with left-sided TN. Discussion and conclusion: MVD is currently the most efficacious surgical option for treating cranial nerve neuralgia. To select patients for MVD, having an MRI criteria for identifying true neurovascular compression will be helpful. However, clinicians should focus more on a patient's clinical symptoms and not rely solely on MRI findings. This patient's case can help clinicians distinguish between TN and GPN, improve the understanding of these diseases, avoid misdiagnosis, and reduce the possibility of secondary damage.

CD28-CAR-T cell activation through FYN kinase signaling rather than LCK enhances therapeutic performance.

Signal transduction induced by chimeric antigen receptors (CARs) is generally believed to rely on the activity of the SRC family kinase (SFK) LCK, as is the case with T cell receptor (TCR) signaling. Here, we show that CAR signaling occurs in the absence of LCK. This LCK-independent signaling requires the related SFK FYN and a CD28 intracellular domain within the CAR. LCK-deficient CAR-T cells are strongly signaled through CAR and have better in vivo efficacy with reduced exhaustion phenotype and enhanced induction of memory and proliferation. These distinctions can be attributed to the fact that FYN signaling tends to promote proliferation and survival, whereas LCK signaling promotes strong signaling that tends to lead to exhaustion. This non-canonical signaling of CAR-T cells provides insight into the initiation of both TCR and CAR signaling and has important clinical implications for improvement of CAR function.

Time required for commitment to T cell proliferation depends on TCR affinity and cytokine response.

T cell activation and effector functions are determined by the affinity of the interaction between T cell receptor (TCR) and its antigenic peptide MHC (pMHC) ligand. A better understanding of the quantitative aspects of TCR-pMHC affinity-dependent T cell activation is critical for the development of new immunotherapeutic strategies. However, the role of TCR-pMHC affinity in regulating the kinetics of CD8+ T cell commitment to proliferation and differentiation is unknown. Here, we show that the stronger the TCR-pMHC affinity, the shorter the time of T cell-APC co-culture required to commit CD8+ T cells to proliferation. The time threshold for T cell cytokine production is much lower than that for cell proliferation. There is a strong correlation between affinity-dependent differences in AKT phosphorylation and T cell proliferation. The cytokine IL-15 increases the poor proliferation of T cells stimulated with low affinity pMHC, suggesting that pro-inflammatory cytokines can override the affinity-dependent features of T cell proliferation.

Non-Stimulatory pMHC Enhance CD8 T Cell Effector Functions by Recruiting Coreceptor-Bound Lck.

Under physiological conditions, CD8+ T cells need to recognize low numbers of antigenic pMHC class I complexes in the presence of a surplus of non-stimulatory, self pMHC class I on the surface of the APC. Non-stimulatory pMHC have been shown to enhance CD8+ T cell responses to low amounts of antigenic pMHC, in a phenomenon called co-agonism, but the physiological significance and molecular mechanism of this phenomenon are still poorly understood. Our data show that co-agonist pMHC class I complexes recruit CD8-bound Lck to the immune synapse to modulate CD8+ T cell signaling pathways, resulting in enhanced CD8+ T cell effector functions and proliferation, both in vitro and in vivo. Moreover, co-agonism can boost T cell proliferation through an extrinsic mechanism, with co-agonism primed CD8+ T cells enhancing Akt pathway activation and proliferation in neighboring CD8+ T cells primed with low amounts of antigen.